Dual specificity phosphatases (DUSPs) modulate the duration and magnitude of phospho-activation of Erk1/2, p38 and JNK1/2, the terminal kinases (TKs) of the mitogen activated protein kinase (MAPK) cas Show more
Dual specificity phosphatases (DUSPs) modulate the duration and magnitude of phospho-activation of Erk1/2, p38 and JNK1/2, the terminal kinases (TKs) of the mitogen activated protein kinase (MAPK) cascades. Three DUSPs, DUSP1, DUSP5, and DUSP6, are overexpressed in ocular surface side population stem cells (SPSCs). Our objective was to identify the impact of these enzymes on TK phosphorylation and proliferation of corneal epithelial cells. SV40 immortalized (sv) and expanded fresh human corneal epithelial cells (efHCECs) were transduced with lentivectors to elicit expression of shRNAmir against DUSP1, DUSP5, and JNK1 to thereby create the DUSP1i, DUSP5i and JNKi cell sublines, or overexpress DUSP6 (henceforth DUSP6(+)), respectively. TK phosphorylation status and proliferation rates were determined by immunoblotting and (3)H thymidine uptake. In both ef and svHCECs, EGF supplementation after a 24 h serum starvation caused a rapid 5-15 min spike in the phosphorylation of all three TK types. This was followed by gradual decreases to low phosphorylation levels within one h. These declines coincided with dramatic increases in DUSP1 and DUSP5 protein expression. In DUSP1i, the DUSP1 increase was abolished. All 3 TKs maintained high phosphorylation levels for at least 90 min and proliferation rates were unchanged from non-transduced cells. In DUSP5i, the DUSP5 protein increase was prevented, the post peak phosphorylation decrease occurred only on Erk1/2 and the proliferation rate increased by 50%-60%. In JNK1i, JNK1 was essentially knocked out and proliferation rates were also markedly elevated. At steady-state, DUSP1i maintained high levels of pJNK1/2 expression. In DUSP6(+) Erk1/2 phosphorylation was prevented and proliferation rates decreased to less than 50%. DUSP5 and DUSP6 selectively control ERK pathway activity and proliferation. The lack of an effect of DUSP1 knockdown on proliferation can be attributed to its pan-MAPK effect. The expected augmented proliferative response due to enhanced and prolonged phosphorylation of Erk1/2 following DUSP1 knockdown does not occur because a pJNK1/2 antiproliferative effect is simultaneously unleashed. Show less
Mitogen-activated protein kinase (MAPK) pathway signaling plays an important role in the majority of non-small-cell lung cancers (NSCLCs). In a prior microarray analysis of epidermal growth factor rec Show more
Mitogen-activated protein kinase (MAPK) pathway signaling plays an important role in the majority of non-small-cell lung cancers (NSCLCs). In a prior microarray analysis of epidermal growth factor receptor (EGFR) inhibition in NSCLC cell lines, we noted that several dual specificity phosphatases (DUSPs) were among the most highly and immediately regulated genes. DUSPs act as natural terminators of MAPK signal transduction and therefore, we hypothesized a tumor suppressive role via feedback mechanisms. In the current study, we focus on the assessment of DUSP6, a cytoplasmic DUSP with high specificity for extracellular signal-regulated kinase (ERK). We demonstrate that DUSP6 expression tracks in tandem with ERK inhibition and that regulation of DUSP6 is mediated at the promoter level by ETS1, a well-known nuclear target of activated ERK. Small interfering RNA knockdown in DUSP6-high H441 lung cancer cells significantly increased ERK activation and cellular proliferation, whereas plasmid-driven overexpression in DUSP6-low H1975 lung cancer cells significantly reduced ERK activation and cellular proliferation and promoted apoptosis. Also, DUSP6 overexpression synergized with EGFR inhibitor treatment in EGFR-mutant HCC827 cells. Our results indicate that DUSP6 expression is regulated by ERK signaling and that DUSP6 exerts antitumor effects via negative feedback regulation, pointing to an important feedback loop in NSCLC. Further studies assessing the tumor suppressive role of DUSP6 and strategies aimed at modulation of its activity are warranted. Show less
Hereditary multiple exostoses (HME) is an autosomal dominant bone disorder characterized by growth of benign multiple exostoses. In our present study, we describe a four-generation Han Chinese kindred Show more
Hereditary multiple exostoses (HME) is an autosomal dominant bone disorder characterized by growth of benign multiple exostoses. In our present study, we describe a four-generation Han Chinese kindred with eight members affected by HME. Haplotyping analysis and mutation detection was performed. The results linked the disease-causing gene to the EXT1 locus on chromosome 8. A novel mutation in EXT1, c.1897delC, which cosegregated with the disease phenotype, was detected. To further confirm this mutation, a mismatch primer was designed to introduce a ScaI restriction site into the normal allele by polymerase chain reaction, and the following restriction fragment length polymorphism analysis demonstrated that the mutation was not detected in any unaffected individuals of the family or 100 unrelated Han Chinese control individuals. This mutation leads to a frameshift from codon 633, resulting in a premature termination at codon 642 and loss of the highly conserved C terminal region of the protein. Therefore, this heterozygous mutation must be classified as pathogenic and can be regarded as the cause of HME in this Chinese family. Show less
Benjamin M Neale, Jesen Fagerness, Robyn Reynolds+23 more · 2010 · Proceedings of the National Academy of Sciences of the United States of America · National Academy of Sciences · added 2026-04-24
Advanced age-related macular degeneration (AMD) is the leading cause of late onset blindness. We present results of a genome-wide association study of 979 advanced AMD cases and 1,709 controls using t Show more
Advanced age-related macular degeneration (AMD) is the leading cause of late onset blindness. We present results of a genome-wide association study of 979 advanced AMD cases and 1,709 controls using the Affymetrix 6.0 platform with replication in seven additional cohorts (totaling 5,789 unrelated cases and 4,234 unrelated controls). We also present a comprehensive analysis of copy-number variations and polymorphisms for AMD. Our discovery data implicated the association between AMD and a variant in the hepatic lipase gene (LIPC) in the high-density lipoprotein cholesterol (HDL) pathway (discovery P = 4.53e-05 for rs493258). Our LIPC association was strongest for a functional promoter variant, rs10468017, (P = 1.34e-08), that influences LIPC expression and serum HDL levels with a protective effect of the minor T allele (HDL increasing) for advanced wet and dry AMD. The association we found with LIPC was corroborated by the Michigan/Penn/Mayo genome-wide association study; the locus near the tissue inhibitor of metalloproteinase 3 was corroborated by our replication cohort for rs9621532 with P = 3.71e-09. We observed weaker associations with other HDL loci (ABCA1, P = 9.73e-04; cholesterylester transfer protein, P = 1.41e-03; FADS1-3, P = 2.69e-02). Based on a lack of consistent association between HDL increasing alleles and AMD risk, the LIPC association may not be the result of an effect on HDL levels, but it could represent a pleiotropic effect of the same functional component. Results implicate different biologic pathways than previously reported and provide new avenues for prevention and treatment of AMD. Show less
Histone lysine acetylation and methylation have an important role during gene transcription in a chromatin context. Knowledge concerning the types of protein modules that can interact with acetyl-lysi Show more
Histone lysine acetylation and methylation have an important role during gene transcription in a chromatin context. Knowledge concerning the types of protein modules that can interact with acetyl-lysine has so far been limited to bromodomains. Recently, a tandem plant homeodomain (PHD) finger (PHD1-PHD2, or PHD12) of human DPF3b, which functions in association with the BAF chromatin remodelling complex to initiate gene transcription during heart and muscle development, was reported to bind histones H3 and H4 in an acetylation-sensitive manner, making it the first alternative to bromodomains for acetyl-lysine binding. Here we report the structural mechanism of acetylated histone binding by the double PHD fingers of DPF3b. Our three-dimensional solution structures and biochemical analysis of DPF3b highlight the molecular basis of the integrated tandem PHD finger, which acts as one functional unit in the sequence-specific recognition of lysine-14-acetylated histone H3 (H3K14ac). Whereas the interaction with H3 is promoted by acetylation at lysine 14, it is inhibited by methylation at lysine 4, and these opposing influences are important during transcriptional activation of the mouse DPF3b target genes Pitx2 and Jmjd1c. Binding of this tandem protein module to chromatin can thus be regulated by different histone modifications during the initiation of gene transcription. Show less
The Kruppel-like factor 2 (KLF2) and Kruppel-like factor 4 (KLF4) transcription factors have recently been shown to act as critical regulators of endothelial homeostasis. While several insights have b Show more
The Kruppel-like factor 2 (KLF2) and Kruppel-like factor 4 (KLF4) transcription factors have recently been shown to act as critical regulators of endothelial homeostasis. While several insights have been made into the signaling mechanisms orchestrating endothelial KLF2 expression, those governing the expression of KLF4 in the vascular endothelium remain largely unknown. Here, we show that diverse vasoprotective stimuli including an atheroprotective shear stress waveform, simvastatin, and resveratrol induce the expression of KLF4 in cultured human endothelial cells. We further demonstrate that the induction of KLF4 by resveratrol and atheroprotective shear stress occurs via a MEK5/MEF2-dependent signaling pathway. Since MEK5 activation is also critical for the expression of KLF2, we assessed the individual contribution of KLF4 and KLF2 to the global transcriptional activity triggered by MEK5 activation. Genome-wide transcriptional profiling of endothelial cells overexpressing KLF4, KLF2, or constitutively active MEK5 revealed that 59.2% of the genes regulated by the activation of MEK5 were similarly controlled by either KLF2 or KLF4. Collectively, our data identify a significant degree of mechanistic and functional conservation between KLF2 and KLF4, and importantly, provide further insights into the complex regulatory networks governing endothelial vasoprotection. Show less
Resveratrol activates Sirtuin 1 (SIRT1), a nicotinamide adenine dinucleotide-dependent deacetylase which modulates metabolic homeostasis and improves several pathophysiological features present in dis Show more
Resveratrol activates Sirtuin 1 (SIRT1), a nicotinamide adenine dinucleotide-dependent deacetylase which modulates metabolic homeostasis and improves several pathophysiological features present in diseases of ageing. In particular, it has been shown that SIRT1 activation improves endothelial dysfunction and suppresses vascular inflammation, two central pathophysiological processes involved in the initiation and progression of cardiovascular disease. The downstream targets of SIRT1 activation in this context, however, remain poorly defined. Therefore, in this study, we aimed to characterize mechanistically how SIRT1 activation regulates the endothelial vasoprotective phenotype. We demonstrate that SIRT1 activation by resveratrol increases the expression of the transcription factor Krüppel-like factor 2 (KLF2) in human vascular endothelial cells, resulting in the orchestrated regulation of transcriptional programs critical for conferring an endothelial vasoprotective phenotype. Moreover, we show that KLF2 upregulation by resveratrol occurs via a mitogen-activated protein kinase 5/myocyte enhancing factor 2-dependent signalling pathway. Collectively, these observations provide a new mechanistic framework to understand the vascular protective effects mediated by SIRT1 activators and define KLF2 as a critical mediator of these effects. Show less
We report a case of a 6-month-old boy with a mixed phenotype acute leukemia (MPAL), bilineal and biphenotypic immunophenotype (B-lymphoid lineage and combined B-lymphoid and monocytic lineage) with t( Show more
We report a case of a 6-month-old boy with a mixed phenotype acute leukemia (MPAL), bilineal and biphenotypic immunophenotype (B-lymphoid lineage and combined B-lymphoid and monocytic lineage) with t(10;11)(p12;q23);MLL-MLLT10. He was treated with acute myeloid leukemia protocol and in complete remission at 7-month follow-up. To the best of our knowledge, this is the first reported MLL-MLLT10 rearranged case presenting as MPAL in an infant. From a clinical practice standpoint, this case illustrates the importance of detection of MLL rearrangement due to its prognostic implication and the effectiveness of flow cytometry immunophenotyping in diagnosing MPAL and monitoring minimal residual disease. Show less
Epigenetic modifications of chromatin play an important role in the regulation of gene expression. KMT4/Dot1 is a conserved histone methyltransferase capable of methylating chromatin on Lys79 of histo Show more
Epigenetic modifications of chromatin play an important role in the regulation of gene expression. KMT4/Dot1 is a conserved histone methyltransferase capable of methylating chromatin on Lys79 of histone H3 (H3K79). Here we report the identification of a multisubunit Dot1 complex (DotCom), which includes several of the mixed lineage leukemia (MLL) partners in leukemia such as ENL, AF9/MLLT3, AF17/MLLT6, and AF10/MLLT10, as well as the known Wnt pathway modifiers TRRAP, Skp1, and beta-catenin. We demonstrated that the human DotCom is indeed capable of trimethylating H3K79 and, given the association of beta-catenin, Skp1, and TRRAP, we investigated, and found, a role for Dot1 in Wnt/Wingless signaling in an in vivo model system. Knockdown of Dot1 in Drosophila results in decreased expression of a subset of Wingless target genes. Furthermore, the loss of expression for the Drosophila homologs of the Dot1-associated proteins involved in the regulation of H3K79 shows a similar reduction in expression of these Wingless targets. From yeast to human, specific trimethylation of H3K79 by Dot1 requires the monoubiquitination of histone H2B by the Rad6/Bre1 complex. Here, we demonstrate that depletion of Bre1, the E3 ligase required for H2B monoubiquitination, leads specifically to reduced bulk H3K79 trimethylation levels and a reduction in expression of many Wingless targets. Overall, our study describes for the first time the components of DotCom and links the specific regulation of H3K79 trimethylation by Dot1 and its associated factors to the Wnt/Wingless signaling pathway. Show less
Glucose regulates programs of gene expression that orchestrate changes in cellular phenotype in several metabolically active tissues. Carbohydrate response element-binding protein (ChREBP) and its bin Show more
Glucose regulates programs of gene expression that orchestrate changes in cellular phenotype in several metabolically active tissues. Carbohydrate response element-binding protein (ChREBP) and its binding partner, Mlx, mediate glucose-regulated gene expression by binding to carbohydrate response elements on target genes, such as the prototypical glucose-responsive gene, liver-type pyruvate kinase (Pklr). c-Myc is also required for the glucose response of the Pklr gene, although the relationship between c-Myc and ChREBP has not been defined. Here we describe the molecular events of the glucose-mediated activation of Pklr and determine the effects of decreasing the activity or abundance of c-Myc on this process. Time-course chromatin immunoprecipitation revealed a set of transcription factors [hepatocyte nuclear factor (HNF)1alpha, HNF4alpha, and RNA polymerase II (Pol II)] constitutively resident on the Pklr promoter, with a relative enrichment of acetylated histones 3 and 4 in the same region of the gene. Glucose did not affect HNF1alpha binding or the acetylation of histones H3 or H4. By contrast, glucose promoted the recruitment of ChREBP and c-Myc and increased the occupancy of HNF4alpha and RNA Pol II, which were coincident with the glucose-mediated increase in transcription as determined by a nuclear run-on assay. Depletion of c-Myc activity using a small molecule inhibitor (10058-F4/1RH) abolished the glucose-mediated recruitment of HNF4alpha, ChREBP, and RNA Pol II, without affecting basal gene expression, histone acetylation, and HNF1alpha or basal HNF4alpha occupancy. The activation and recruitment of ChREBP to several glucose-responsive genes were blocked by 1RH, indicating a general necessity for c-Myc in this process. Show less
Heart failure is a leading cause of death of people in South Asia, and cardiomyopathy is a major cause of heart failure. Myosin binding protein C (MYBPC3) is expressed in the heart muscle, where it re Show more
Heart failure is a leading cause of death of people in South Asia, and cardiomyopathy is a major cause of heart failure. Myosin binding protein C (MYBPC3) is expressed in the heart muscle, where it regulates the cardiac response to adrenergic stimulation and is important for the structural integrity of the sarcomere. Mutations in the MYBPC3 gene are associated with hypertrophic or dilated cardiomyopathies. A 25-base-pair deletion in intron 32 causes skipping of the downstream exon and is associated with familial cardiomyopathy. To date, this deletion is found primarily in India and South Asia, although it is also found at low frequency in Southeast Asia. In order to better characterise the distribution of this variant, we determined its frequency in 447 individuals from 19 populations, including 10 populations from India and neighbouring populations from Pakistan and Nepal. The deletion frequency is over 8% in some of our Indian samples, and it is not present in any of the populations we sampled outside of India. The differences in the deletion frequencies among populations in India are consistent with patterns of variation previously reported and with patterns we observed among Indian populations based on high-density SNP chip data. Our results indicate that the MYBPC3 deletion is primarily found among Indian populations and that its distribution is consistent with genome-wide patterns of variation in India. Show less
Liver X receptors (LXRs) promote macrophage reverse cholesterol transport and cholesterol excretion from the body. The synthetic LXR ligands T0901317 and GW3965 were shown to significantly inhibit ath Show more
Liver X receptors (LXRs) promote macrophage reverse cholesterol transport and cholesterol excretion from the body. The synthetic LXR ligands T0901317 and GW3965 were shown to significantly inhibit atherosclerosis in mice and to increase the expression of ATP-binding cassette transporter A1 (ABCA1) in the atherosclerotic lesions. However, these compounds increase plasma and hepatic triglyceride (TG) levels in mice. Methyl-3β-hydroxy-5α,6α-epoxycholanate (MHEC), synthesized from hyodeoxycholic acid, functions as an LXR agonist, but its role in atherogenesis and lipid metabolism remained to be elucidated. THP-1-derived macrophages were cultured in the medium con- taining various concentrations of MHEC or T0901317 (0-10 μmol/l) for 24 h. Reverse transcription polymerase chain reaction was used to quantify LXRα, LXRβ and ABCA1 mRNA levels in macrophages. Additionally, MHEC or T0901317 was orally administered at 10 mg/kg daily for 6 weeks in apolipoprotein E knockout (apoE⁻/⁻) mice fed a high-cholesterol diet. Plasma lipids were determined enzymatically. The area of and ABCA1 expression in the aortic atherosclerotic lesions were measured by oil red O staining and immunohistochemistry, respectively. Both MHEC and T0901317 equally stimulated LXRα and ABCA1 mRNA expression in a dose-dependent manner in THP-1-derived macrophages, but they did not induce LXRβ mRNA expression significantly. The plasma levels of total cholesterol, TG and high-density lipoprotein cholesterol were significantly higher in T0901317-treated mice than in the vehicle-treated control group. Interestingly, MHEC treatment dramatically increased plasma high-density lipoprotein cholesterol without altering plasma levels of total cholesterol and TG. Both MHEC and T0901317 equally inhibited the development of atherosclerotic lesions in apoE⁻/⁻ mice. The expression of ABCA1, a cholesterol efflux transporter, was greatly induced by the two LXR agonists in the artery wall. MHEC is a novel LXR agonist and it inhibits atherosclerosis in apoE⁻/⁻ mice without raising blood TG. Thus, MHEC relative to T0901317 may be a better therapeutic LXR agonist for the treatment of atherosclerosis. Show less
The liver X receptor (LXR) and constitutive androstane receptor (CAR) are two nuclear receptors postulated to have distinct functions. LXR is a sterol sensor that promotes lipogenesis, whereas CAR is Show more
The liver X receptor (LXR) and constitutive androstane receptor (CAR) are two nuclear receptors postulated to have distinct functions. LXR is a sterol sensor that promotes lipogenesis, whereas CAR is a xenosensor that controls xenobiotic responses. Here, we show that LXRα and CAR are functionally related in vivo. Loss of CAR increased the expression of lipogenic LXR target genes, leading to increased hepatic triglyceride accumulation, whereas activation of CAR inhibited the expression of LXR target genes and LXR ligand-induced lipogenesis. On the other hand, a combined loss of LXR α and β increased the basal expression of xenobiotic CAR target genes, whereas activation of LXR inhibited the expression of CAR target genes and sensitized mice to xenobiotic toxicants. The mutual suppression between LXRα and CAR was also observed in cell culture and reporter gene assays. LXRα, like CAR, exhibited constitutive activity in the absence of an exogenously added ligand by recruiting nuclear receptor coactivators. Interestingly, although CAR competed with LXRα for coactivators, the constitutive activity and recruitment of coactivators was not required for CAR to suppress the activity of LXRα. In vivo chromatin immunoprecipitation assay showed that cotreatment of a CAR agonist compromised the LXR agonist responsive recruitment of LXRα to Srebp-1c, whereas an LXR agonist inhibited the CAR agonist-responsive recruitment of CAR to Cyp2b10. In conclusion, our results have revealed dual functions of LXRα and CAR in lipogenesis and xenobiotic responses, establishing a unique role of these two receptors in integrating xenobiotic and endobiotic homeostasis. Show less
The mechanisms of action of vitamin A deficiency (VAD) on lipid metabolism in the rat kidney were investigated in adult female rats and their offspring. The rats were randomized into three groups: (1) Show more
The mechanisms of action of vitamin A deficiency (VAD) on lipid metabolism in the rat kidney were investigated in adult female rats and their offspring. The rats were randomized into three groups: (1) control, in which the mother and offspring received a normal diet (4000 retinol IU/kg diet) for 8 weeks; (2) VAD group, in which the mothers and offspring received a VAD diet (400 retinol IU/kg diet) for 8 weeks; (3) vitamin A-refed group, in which a group of pups on a VAD diet for 8 weeks received a complete diet (6500 retinol IU/kg diet) for 15 days. The lipid metabolism of the offsprings' kidneys and its relation to the expression of apolipoprotein B100 (Apo-B100), liver X receptor alpha (LXRalpha), and retinoid X receptor-alpha/beta (RXRalpha/beta) mRNA was analyzed. VAD was found to alter renal lipid metabolism and its immune environment due to the expression of Apo-B100. Compared with the control, VAD rats had significantly higher levels of transforming growth factor-beta 1 and lower levels of ABCA1, a key gene involved in cholesterol efflux and tissue lipid homeostasis. The expression of LXRalpha and RXRalpha/beta mRNA also decreased in the VAD rat kidney. Vitamin A refeeding reversed all of the changes. Lipid metabolism involved in renal reverse cholesterol transport may be mediated by decreasing the signaling through the ABCA1 cholesterol efflux pathway, which is significantly modified in kidneys of vitamin A-deficient rats. Show less
Ning Li, Moisés A Rivéra-Bermúdez, Mei Zhang+10 more · 2010 · Proceedings of the National Academy of Sciences of the United States of America · National Academy of Sciences · added 2026-04-24
Osteoarthritis (OA), the most common arthritic condition in humans, is characterized by the progressive degeneration of articular cartilage accompanied by chronic joint pain. Inflammatory mediators, s Show more
Osteoarthritis (OA), the most common arthritic condition in humans, is characterized by the progressive degeneration of articular cartilage accompanied by chronic joint pain. Inflammatory mediators, such as cytokines and prostaglandin E(2) (PGE(2)) that are elevated in OA joints, play important roles in the progression of cartilage degradation and pain-associated nociceptor sensitivity. We have found that the nuclear receptor family transcription factors Liver X Receptors (LXRalpha and -beta) are expressed in cartilage, with LXRbeta being the predominant isoform. Here we show that genetic disruption of Lxrbeta gene expression in mice results in significantly increased proteoglycan (aggrecan) degradation and PGE(2) production in articular cartilage treated with IL-1beta, indicating a protective role of LXRbeta in cartilage. Using human cartilage explants, we found that activation of LXRs by the synthetic ligand GW3965 significantly reduced cytokine-induced degradation and loss of aggrecan from the tissue. Furthermore, LXR activation dramatically inhibited cytokine-induced PGE(2) production by human osteoarthritic cartilage as well as by a synovial sarcoma cell line. These effects were achieved at least partly by repression of the expression of ADAMTS4, a physiological cartilage aggrecanase, and of cyclooxygenase-2 and microsomal prostaglandin E synthase-1, key enzymes in the PGE(2) synthesis pathway. Consistent with our in vitro observations, oral administration of GW3965 potently alleviated joint pain in a rat meniscal tear model of osteoarthritis. Show less
Kenichi Matsushita, Fulvio Morello, Yaojiong Wu+4 more · 2010 · The Journal of biological chemistry · American Society for Biochemistry and Molecular Biology · added 2026-04-24
Renin is a key enzyme for cardiovascular and renal homeostasis and is produced by highly specialized endocrine cells in the kidney, known as juxtaglomerular (JG) cells. The nature and origin of these Show more
Renin is a key enzyme for cardiovascular and renal homeostasis and is produced by highly specialized endocrine cells in the kidney, known as juxtaglomerular (JG) cells. The nature and origin of these cells remain as mysteries. Previously, we have shown that the nuclear hormone receptor liver X receptor-alpha (LXRalpha) is a major transcriptional regulator of the expression of renin, c-myc, and other genes involved with growth/differentiation. In this study we test the hypothesis that LXRalpha plays an important role not only in renin expression but also in renin-containing cell differentiation, specifically from the mesenchymal stem cell (MSC), which may be the origin of the JG cell. Indeed, our data demonstrated that LXRalpha activation by its ligands or cAMP stimulated renin gene expression in both murine and human MSCs. Furthermore, sustained cAMP stimulation of murine MSCs overexpressing LXRalpha led to their differentiation into JG-like cells expressing renin and alpha-smooth muscle actin. These MSC-derived JG-like cells contained renin in secretory granules and released active renin in response to cAMP. In conclusion, the activation of LXRalpha stimulates renin expression and induces MSCs differentiation into renin-secreting, JG-like cells. Our results suggest that the MSC may be the origin of the juxtaglomerular cell and provide insight into novel understanding of pathophysiology of the renin-angiotensin system. Show less
Traumatic brain injury (TBI), a major cause of morbidity and mortality, is a serious public health concern. To evaluate the effect of mild hypothermia on gene expression in the hippocampus and to try Show more
Traumatic brain injury (TBI), a major cause of morbidity and mortality, is a serious public health concern. To evaluate the effect of mild hypothermia on gene expression in the hippocampus and to try to elucidate molecular mechanisms of hypothermic neuroprotection after TBI. Rats were subjected to mild hypothermia (group 1: n = 3, 33 degrees C, 3H) or normothermia (group 2: n = 3; 37 degrees C, 3H) after TBI. Six genome arrays were applied to detect the gene expression profiles of ipsilateral hippocampus. Functional clustering and gene ontology analysis were then carried out. Another 20 rats were randomly assigned to 4 groups (n = 5 per group): group 3, sham-normothermia; group 4, sham-hypothermia; group 5, TBI-normothermia; and group 6, TBI-hypothermia. Real-time fluorescent quantitative reverse-transcription polymerase chain reaction was used to detect specific selected genes. We found that 133 transcripts in the hypothermia group were statistically different from those in the normothermia group, including 57 transcripts that were upregulated and 76 that were downregulated after TBI (P < .01). Most of these genes were involved in various pathophysiological processes, and some were critical to cell survival. Analysis showed that 9 gene ontology categories were significantly affected by hypothermia, including the most affected categories: synapse organization and biogenesis (upregulated) and regulation of inflammatory response (downregulated). The mRNA expression of Ank3, Cmbp, Nrxn3, Tgm2, and Fcgr3 was regulated by hypothermia, TBI, or a combination of TBI and hypothermia compared with the sham-normothermia group. Their mRNA expression was significantly regulated by hypothermia in TBI groups. Posttraumatic mild hypothermia has a significant effect on the gene expression profiles of the hippocampus, especially those genes belonging to the 9 gene ontology categories. Differential expression of those genes may be involved in the most fundamental molecular mechanisms of cerebral protection by mild hypothermia after TBI. Show less
Accumulated studies reported that the natruretic dopamine (DA) and the anti-natruretic angiotensin II (Ang II) represent an important mechanism to regulate renal Na(+) and water excretion through intr Show more
Accumulated studies reported that the natruretic dopamine (DA) and the anti-natruretic angiotensin II (Ang II) represent an important mechanism to regulate renal Na(+) and water excretion through intracellular secondary messengers to inhibit or activate renal proximal tubule (PT) Na(+), K(+)-ATPase (NKA). The antagonistic actions were mediated by the phosphorylation of different position of NKA α₁-subunit and different Pals-associated tight junction protein (PATJ) PDZ domains, the different protein kinase C (PKC) isoforms (PKC-β, PKC-ζ), the common adenylyl cyclase (AC) pathway, and the crosstalk and balance between DA and Ang II to NKA regulation. Besides, Ang II-mediated NKA modulation has bi-phasic effects. Show less
Cell polarity proteins regulate tight junction formation and directional migration in epithelial cells. To date, the mechanism by which these polarity proteins assemble at the leading edge of migratin Show more
Cell polarity proteins regulate tight junction formation and directional migration in epithelial cells. To date, the mechanism by which these polarity proteins assemble at the leading edge of migrating epithelial cells remains unclear. We report that occludin, a transmembrane protein, is localized at the leading edge of migrating cells and regulates directional cell migration. During migration, occludin knockdown disrupted accumulation of aPKC-Par3 and PATJ at the leading edge, and led to a disorganized microtubule network and defective reorientation of the microtubule organization center (MTOC). Phosphorylation of occludin at tyrosine 473 residue allowed recruitment of p85 alpha to the leading edge via association with its C-terminal SH2 domain. Loss of occludin attenuated activation of PI3K, leading to disorganization of the actin cytoskeleton and reduced cell protrusions. Our data indicate that occludin is required for the leading-edge localization of polarity proteins aPKC-Par3 and PATJ and promotes cell protrusion by regulating membrane-localized activation of PI3K. Show less
In contrast to its extensively studied intracellular roles, the molecular mechanisms by which extracellular Ca(2+) regulates the basal excitability of neurons are unclear. One mechanism is believed to Show more
In contrast to its extensively studied intracellular roles, the molecular mechanisms by which extracellular Ca(2+) regulates the basal excitability of neurons are unclear. One mechanism is believed to be through Ca(2+)'s interaction with the negative charges on the cell membrane (the charge screening effect). Here we show that, in cultured hippocampal neurons, lowering [Ca(2+)](e) activates a NALCN channel-dependent Na(+)-leak current (I(L-Na)). The coupling between [Ca(2+)](e) and NALCN requires a Ca(2+)-sensing G protein-coupled receptor, an activation of G-proteins, an UNC80 protein that bridges NALCN to a large novel protein UNC79 in the same complex, and the last amino acid of NALCN's intracellular tail. In neurons from nalcn and unc79 knockout mice, I(L-Na) is insensitive to changes in [Ca(2+)](e), and reducing [Ca(2+)](e) fails to elicit the excitatory effects seen in the wild-type. Therefore, extracellular Ca(2+) influences neuronal excitability through the UNC79-UNC80-NALCN complex in a G protein-dependent fashion. Show less
Ying Gao, Ke Wu, Yi Xu+9 more · 2009 · Journal of Huazhong University of Science and Technology. Medical sciences = Hua zhong ke ji da xue xue bao. Yi xue Ying De wen ban = Huazhong keji daxue xuebao. Yixue Yingdewen ban · Springer · added 2026-04-24
To identify acute renal allograft rejection biomarkers in human serum, two-dimensional differential in-gel electrophoresis (2-D DIGE) and reversed phase high-performance liquid chromatography (RP-HPLC Show more
To identify acute renal allograft rejection biomarkers in human serum, two-dimensional differential in-gel electrophoresis (2-D DIGE) and reversed phase high-performance liquid chromatography (RP-HPLC) followed by electrospray ionization mass spectrometry (ESI-MS) were used. Serum samples from renal allograft patients and normal volunteers were divided into three groups: acute rejection (AR), stable renal function (SRF) and normal volunteer (N). Serum samples were firstly processed using Multiple Affinity Removal Column to selectively remove the highest abundance proteins. Differentially expressed proteins were analyzed using 2-D DIGE. These differential protein spots were excised, digested by trypsin, and identified by RP-HPLC-ESI/MS. Twenty-two differentially expressed proteins were identified in serum from AR group. These proteins included complement C9 precursor, apolipoprotein A-IV precursor, vitamin D-binding protein precursor, beta-2-glycoprotein 1 precursor, etc. Vitamin D-binding protein, one of these proteins, was confirmed by ELISA in the independent set of serum samples. In conclusion, the differentially expressed proteins as serum biomarker candidates may provide the basis of acute rejection noninvasive diagnosis. Confirmed vitamin D-binding protein may be one of serum biomarkers of acute rejection. Furthermore, it may provide great insights into understanding the mechanisms and potential treatment strategy of acute rejection. Show less
The apolipoproteins (APOA1/C3/A4/A5) are key components in modulating lipoprotein metabolism. It is unknown whether variants at the APOA1/C3/A4/A5 gene cluster are associated with lipid response to ph Show more
The apolipoproteins (APOA1/C3/A4/A5) are key components in modulating lipoprotein metabolism. It is unknown whether variants at the APOA1/C3/A4/A5 gene cluster are associated with lipid response to pharmacologic intervention. Plasma triglycerides (TGs) and high-density lipoprotein (HDL) levels were measured in 861 Genetics of Lipid-Lowering Drugs and Diet Network study participants who underwent a 3-week fenofibrate trial. We examined 18 common single nucleotide polymorphisms (SNPs) spanning the APOA1/C3/A4/A5 genes to investigate the effects of variants at the gene cluster on lipid response to fenofibrate treatment. We found that the minor alleles of the SNPs rs3135506 (APOA5_S19W), rs5104 (APOA4_N147S), rs4520 (APOC3_G34G), and rs5128 (APOC3₃U386) were associated with enhanced TG response to fenofibrate treatment (P= 0.0004-0.018). The minor allele of SNP rs2854117 (APOC3_M482) was associated with reduced rather than enhanced TG response (P= 0.026). The SNP rs3135506 (APOA5_S19W) was associated with HDL response, with minor allele related to reduced HDL response to fenofibrate (P= 0.002). Association analyses on haplotype provided corroborative evidence to single SNP association analyses. The common haplotypes H2, H3, and H5 were significantly associated with reduced TG response to fenofibrate. The genetic variants at APOA1/C3/A4/A5 gene cluster may be useful markers to predict response of lipid-lowering therapy with fenofibrate. Further studies to replicate/confirm our findings are warranted. Show less
To explore the relationship between serum apolipoprotein A5 (ApoA5) and lipid profile or high sensitive C-reactive protein (hs-CRP) in patients with acute coronary syndrome (ACS). Serum apoA5 and hs-C Show more
To explore the relationship between serum apolipoprotein A5 (ApoA5) and lipid profile or high sensitive C-reactive protein (hs-CRP) in patients with acute coronary syndrome (ACS). Serum apoA5 and hs-CRP levels were measured by ELISA and immunoturbidimetry in control subjects (n = 232), patients with stable angina (SA, n = 127), unstable angina (UA, n = 116) and acute myocardial infarction (AMI, n = 112). Triglyceride (TG), total cholesterol (TC), high density lipoprotein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C) were also measured. Compared with controls [(108.7 +/- 23.2) microg/L] and SA patients [(78.3 +/- 20.2) microg/L], serum ApoA5 level was significantly increased in UA [(340.6 +/- 63.5) microg/L] and AMI patients [(373.2 +/- 73.8) microg/L] (all P < 0.05). ApoA5 was positively correlated with TG (r = 0.63 and 0.67, respectively, all P < 0.05) and hs-CRP (r = 0.57 and 0.55, respectively, all P < 0.05) in UA and AMI patients but there were no significant correlations between ApoA5 and TC, HDL-C and LDL-C in ACS patients (all P > 0.05). Increased serum apoA5 level and the positive correlation between ApoA5 and serum TG and hs-CRP in ACS patients might reflect increased inflammation responses in ACS patients. Show less
Combining statin and fibrate in clinical practice provides a greater reduction of triglycerides than either drug given alone, but the mechanism for this effect is poorly understood. Apolipoprotein AV Show more
Combining statin and fibrate in clinical practice provides a greater reduction of triglycerides than either drug given alone, but the mechanism for this effect is poorly understood. Apolipoprotein AV (apoAV) has been implicated in triglyceride metabolism. This study was designed to investigate the effect of the combination of statin and fibrate on apoAV and the underlying mechanism(s). Hypertriglyceridaemia was induced in rats by giving them 10% fructose in drinking water for 2 weeks. They were then treated with atorvastatin, fenofibrate or the two agents combined for 4 weeks, and plasma triglyceride and apoAV measured. We also tested the effects of these two agents on triglycerides and apoAV in HepG2 cells in culture. Western blot and reverse transcription polymerase chain reaction was used to measure apoAV and peroxisome proliferator-activated receptor-alpha (PPARalpha) expression. The combination of atorvastatin and fenofibrate resulted in a greater decrease in plasma triglycerides and a greater increase in plasma and hepatic apoAV than either agent given alone. Hepatic expression of the PPARalpha was also more extensively up-regulated in rats treated with the combination. A similar, greater increase in apoAV and a greater decrease in triglycerides were observed following treatment of HepG2 cells pre-exposed to fructose), with the combination. Adding an inhibitor of PPARalpha (MK886) abolished the effects of atorvastatin on HepG2 cells. A combination of atorvastatin and fenofibrate increased apoAV and decreased triglycerides through up-regulation of PPARalpha. Show less
Increased triglyceride (TG) occurs in patients with acute coronary syndrome (ACS), and apolipoprotein AV (apoAV) has been shown to lower TG levels. In the present study, we investigated plasma apoAV l Show more
Increased triglyceride (TG) occurs in patients with acute coronary syndrome (ACS), and apolipoprotein AV (apoAV) has been shown to lower TG levels. In the present study, we investigated plasma apoAV level and its relationship with TG and C-reactive protein (CRP) in ACS patients. A total of 459 subjects were recruited and categorized into control group (n = 116), stable angina (SA) group (n = 115), unstable angina group (n = 116) and acute myocardial infarction group (n = 112). Plasma apoAV level was measured by a sandwich ELISA assay. Compared with controls ((100.27 +/- 22.44) ng/ml), plasma apoAV was decreased in SA patients ((76.54 +/- 16.91) ng/ml) but increased in patients with unstable angina ((330.89 +/- 66.48) ng/ml, P < 0.05) or acute myocardial infarction ((368.66 +/- 60.53) ng/ml, P < 0.05). Inverse correlations between apoAV and TG were observed in the control or stable angina groups (r = -0.573 or -0.603, respectively, P < 0.001), whereas positive correlations were observed in the patients with unstable angina or acute myocardial infarction (r = 0.696 or 0.690, respectively, P < 0.001). Furthermore, a positive relationship between apoAV and CRP was observed in the ACS patients but not in the non-ACS subjects. The plasma apoAV concentration is increased and positively correlates with TG and CRP in ACS patients. Show less
Dyslipidemia is common in patients with acute coronary syndromes (ACS) but the mechanism remains unclear. Apolipoprotein AV (apoAV), a novel member of apolipoprotein family, is involved in lipid metab Show more
Dyslipidemia is common in patients with acute coronary syndromes (ACS) but the mechanism remains unclear. Apolipoprotein AV (apoAV), a novel member of apolipoprotein family, is involved in lipid metabolism. This study was to investigate plasma apoAV level and its association with lipids and high-sensitivity C-reactive protein (hs-CRP) in ACS patients. ACS patients (n=228) and healthy volunteers (n=232) were included. Plasma apoAV levels were measured by an ELISA method. Compared with controls, ACS patients had higher plasma apoAV, hs-CRP, triglycerides, total cholesterol and LDL cholesterol, as well as lower HDL cholesterol. Interestingly, a positive correlation was observed between apoAV and triglycerides in ACS patients, as compared with a negative correlation in controls. Notably, logistic regression analysis showed that plasma apoAV level was an independent predictor of ACS (OR=0.82, 95% CI 0.70-0.95, p<0.05). Furthermore, both apoAV and triglycerides were positively associated with hs-CRP in ACS patients. However, no significant correlations between apoAV and cholesterol including total cholesterol, HDL cholesterol and LDL cholesterol were observed in ACS patients. Thus, apoAV is an independent predictor of ACS although increased plasma apoAV level is positively correlated with triglycerides in ACS patients. Moreover, plasma cholesterol levels are not influenced by apoAV in ACS patients. Show less
Two groups of Chinese hypertriacylglycerolemic subjects were recruited and randomized to medium- and long-chain triacylglycerols (MLCT) oil or long-chain triacylglycerols (LCT) oil. Two subgroups were Show more
Two groups of Chinese hypertriacylglycerolemic subjects were recruited and randomized to medium- and long-chain triacylglycerols (MLCT) oil or long-chain triacylglycerols (LCT) oil. Two subgroups were divided by age at less or more 60 years in both groups. Both oils were consumed at 25-30 g daily for 8 weeks. Anthropometry, blood biochemicals, and computed tomography (CT) scanning were done at the initial and final times. In subjects of age less than 60 years on MLCT, the body weight, body mass index (BMI), waist circumference (WC), hip circumference (HC), waist-hip ratio (WHR), body fat, total fat area, and subcutaneous fat area were significantly lower than those of the initial values, and the change values in these indicators and visceral fat area lowered significantly as compared with those on LCT. The levels of apoB, apoA2, apoC2, and apoC3 decreased significantly, and the change in values in the levels of triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), apoA1, apoB, apoA2, apoC2, apoC3 were significantly lower on MLCT of age under 60 years as compared with those on LCT. Show less
The glyco-isoforms of intact apolipoprotein C3 (ApoC3) were used to probe glycomic changes associated with obesity and recovery following bariatric surgery, liver diseases such as chronic hepatitis C Show more
The glyco-isoforms of intact apolipoprotein C3 (ApoC3) were used to probe glycomic changes associated with obesity and recovery following bariatric surgery, liver diseases such as chronic hepatitis C (CHC) and alcoholic liver cirrhosis, as well as severe, multiorgan diseases such as sepsis and graft vs host disease (GVHD). ApoC3 glyco-isoform ratios responded to unique stimuli that did not correlate with serum lipids or with other blood components measured in either a control population or a group of extremely obese individuals. However, glyco-isoform ratios correlated with obesity with a 1.8-fold change among subjects eligible for bariatric surgery relative to a nonobese control population. Bariatric surgery resulted in rapid change of isoform distribution to that of nonobese individuals, after which the distribution was stable in each individual. Although multiple simultaneous factors complicated effector attribution, the isoform ratios of very obese individuals were nearly normal for diabetic individuals on metformin therapy. Glyco-isoform ratios were sensitive to liver diseases such as chronic hepatitis C and alcoholic liver cirrhosis. The correlation coefficient with fibrosis was superior to that of current assays of serum enzyme levels. Diseases of pregnancy that can result in liver damage, HELLP syndrome and pre-eclampsia, did not alter ApoC3 glyco-isoform ratios. Early after umbilical cord blood transplantation the isoform ratios changed and returned to normal in long-term survivors. Larger changes were observed in persons who died. GVHD had little effect. Persons with severe sepsis showed altered ratios. Similar cut-points for mortality (3.5-fold difference from controls) were found for UCBT and sepsis. Similar values characterized liver cirrhosis. Overall, while changes of glyco-isoform ratios occurred in many situations, individual stability of isoform distribution was evident and large changes were limited to high-level disease. If ratio changes associated with obesity are found to document a risk factor for long-term outcomes, the information provided by glyco-isoform ratio changes may provide important, novel information for diagnostic, prognostic and therapy response to metabolic conditions. Show less
Expression of the c-Myc proto-oncoprotein is tightly regulated in normal cells. Phosphorylation at two conserved residues, threonine58 (T58) and serine62 (S62), regulates c-Myc protein stability. In c Show more
Expression of the c-Myc proto-oncoprotein is tightly regulated in normal cells. Phosphorylation at two conserved residues, threonine58 (T58) and serine62 (S62), regulates c-Myc protein stability. In cancer cells, c-Myc can become aberrantly stabilized associated with altered T58 and S62 phosphorylation. A complex signalling cascade involving GSK3beta kinase, the Pin1 prolyl isomerase, and the PP2A-B56alpha phosphatase controls phosphorylation at these sites. We report here a novel role for the tumour suppressor scaffold protein Axin1 in facilitating the formation of a degradation complex for c-Myc containing GSK3beta, Pin1, and PP2A-B56alpha. Although knockdown of Axin1 decreases the association of c-Myc with these proteins, reduces T58 and enhances S62 phosphorylation, and increases c-Myc stability, acute expression of Axin1 reduces c-Myc levels and suppresses c-Myc transcriptional activity. Moreover, the regulation of c-Myc by Axin1 is impaired in several tested cancer cell lines with known stabilization of c-Myc or loss of Axin1. This study provides critical insight into the regulation of c-Myc expression, how this can be disrupted in three cancer types, and adds to our knowledge of the tumour suppressor activity of Axin1. Show less
Carbamoyl phosphate synthetase I (CPS1), normally found in hepatocytes and small-intestine (SI) enterocytes, is the antigen of Hep Par 1 antibody. Expression of CPS1 in invasive SI adenocarcinoma seem Show more
Carbamoyl phosphate synthetase I (CPS1), normally found in hepatocytes and small-intestine (SI) enterocytes, is the antigen of Hep Par 1 antibody. Expression of CPS1 in invasive SI adenocarcinoma seems to be lost. We retrospectively collected 36 total specimens, which included 31 SI adenomas and 21 adenocarcinomas. We used 34 cases of duodenitis as a control group. Immunohistochemical and Western blot analyses were performed to determine CPS1 expression. The normal SI mucosa, all 34 cases of duodenitis, and all 29 adenomas with low-grade dysplasia demonstrated diffuse Hep Par 1 expression. Of the 21 invasive adenocarcinomas, 15 lost antigen expression (71%). These data are statistically significant (P < .05). Western blot analysis confirmed the immunohistochemical findings, with strong CPS1 expression within the normal mucosa and adenoma and complete loss in the invasive tumor. The differential expression of Hep Par 1 in dysplastic vs malignant tumors of the SI may be diagnostically useful in difficult cases. Show less