APPL1 is an effector of the small GTPase Rab5. Together, they mediate a signal transduction pathway initiated by ligand binding to cell surface receptors. Interaction with Rab5 is confined to the amin Show more
APPL1 is an effector of the small GTPase Rab5. Together, they mediate a signal transduction pathway initiated by ligand binding to cell surface receptors. Interaction with Rab5 is confined to the amino (N)-terminal region of APPL1. We report the crystal structures of human APPL1 N-terminal BAR-PH domain motif. The BAR and PH domains, together with a novel linker helix, form an integrated, crescent-shaped, symmetrical dimer. This BAR-PH interaction is likely conserved in the class of BAR-PH containing proteins. Biochemical analyses indicate two independent Rab-binding sites located at the opposite ends of the dimer, where the PH domain directly interacts with Rab5 and Rab21. Besides structurally supporting the PH domain, the BAR domain also contributes to Rab binding through a small surface region in the vicinity of the PH domain. In stark contrast to the helix-dominated, Rab-binding domains previously reported, APPL1 PH domain employs beta-strands to interact with Rab5. On the Rab5 side, both switch regions are involved in the interaction. Thus we identified a new binding mode between PH domains and small GTPases. Show less
Ubiquitination and the degradation of the large subunit of RNA polymerase II, Rpb1, is not only involved in DNA damage-induced arrest but also in other transcription-obstructing events. However, the u Show more
Ubiquitination and the degradation of the large subunit of RNA polymerase II, Rpb1, is not only involved in DNA damage-induced arrest but also in other transcription-obstructing events. However, the ubiquitin ligases responsible for DNA damage-independent processes in mammalian cells remain to be identified. Here, we identified Wwp2, a mouse HECT domain ubiquitin E3 ligase, as a novel ubiquitin ligase of Rpb1. We found that Wwp2 specifically interacted with mouse Rpb1 and targeted it for ubiquitination both in vitro and in vivo. Interestingly, the interaction with and ubiquitination of Rpb1 was dependent neither on its phosphorylation state nor on DNA damage. However, the enzymatic activity of Wwp2 was absolutely required for its ubiquitin modification of Rpb1. Furthermore, our study indicates that the interaction between Wwp2 and Rpb1 was mediated through WW domain of Wwp2 and C-terminal domain of Rpb1, respectively. Strikingly, downregulation of Wwp2 expression compromised Rpb1 ubiquitination and elevated its intracellular steady-state protein level significantly. Importantly, we identified six lysine residues in the C-terminal domain of Rpb1 as ubiquitin acceptor sites mediated by Wwp2. These results indicate that Wwp2 plays an important role in regulating expression of Rpb1 in normal physiological conditions. Show less
Calcium plays a fundamental role as second messenger in intracellular signaling and bone serves as the body's calcium reserve to tightly maintain blood calcium levels. Calcium in ingested meal is the Show more
Calcium plays a fundamental role as second messenger in intracellular signaling and bone serves as the body's calcium reserve to tightly maintain blood calcium levels. Calcium in ingested meal is the main supply and inadequate calcium intake causes osteoporosis and bone fracture. Here, we describe a novel mechanism of how ingested calcium is deposited on bone. Meal ingestion elicits secretion of the gut hormone gastric inhibitory polypeptide (GIP) from endocrine K cells in the duodenum. Bone histomorphometrical analyses revealed that bone formation parameters in the mice lacking GIP receptor (GIPR(-/-)) were significantly lower than those of wild-type (GIPR(+/+)) mice, and that the number of osteoclasts, especially multinuclear osteoclasts, was significantly increased in GIPR(-/-) mice, indicating that GIPR(-/-) mice have high-turnover osteoporosis. In vitro examination showed the percentage of osteoblastic cells undergoing apoptosis to be significantly decreased in the presence of GIP. Because GIPR(-/-) mice exhibited an increased plasma calcium concentration after meal ingestion, GIP directly links calcium contained in meal to calcium deposition on bone. Show less
Individuals with type 1 diabetes have an increased incidence of coronary artery disease (CAD) and a higher risk of cardiovascular death compared with individuals of the same age in the general populat Show more
Individuals with type 1 diabetes have an increased incidence of coronary artery disease (CAD) and a higher risk of cardiovascular death compared with individuals of the same age in the general population. While chronic hyperglycaemia and insulin resistance partially explain excess CAD, little is known about the potential genetic determinants of accelerated coronary atherosclerosis in type 1 diabetes. The aim of the present study was to evaluate the association of apolipoprotein A-IV (APOA4) polymorphisms with coronary artery calcification (CAC) progression, a marker of subclinical atherosclerosis. Two previously well-studied functional APOA4 polymorphisms resulting in the substitution of the amino acid Thr for Ser at codon 347 and Gln for His at codon 360 were genotyped in 634 subjects with type 1 diabetes and 739 non-diabetic control subjects, the participants of the prospective Coronary Artery Calcification in Type 1 Diabetes (CACTI) study. The His360 allele was associated with a significantly higher risk of CAC progression among patients with type 1 diabetes (33.7 vs 21.2%, p=0.014), but not in the control subjects (14.1 vs 11.1%, p=0.42). Logistic regression analysis confirmed that the presence of the APOA4 His360 allele predicts an increased risk of progression of coronary atherosclerosis in adults with type 1 diabetes of long duration (odds ratio = 3.3, p=0.003 after adjustment for covariates associated with CAD risk). CONCLUSIONS /INTERPRETATION: This is the first report suggesting an association between the APOA4 Gln360His polymorphism and risk of CAC progression in subjects with type 1 diabetes. Additional studies are needed to explore potential interactions between APOA4 genotypes and metabolic/oxidative stress components of the diabetic milieu leading to rapid progression of atherosclerosis. Show less
Schizophrenia is a relatively common psychiatric syndrome that affects virtually all brain functions. We investigated the plasma proteome of 22 schizophrenia male patients and 20 healthy male controls Show more
Schizophrenia is a relatively common psychiatric syndrome that affects virtually all brain functions. We investigated the plasma proteome of 22 schizophrenia male patients and 20 healthy male controls using two-dimensional gel electrophoresis and mass spectrometry. In total, we have identified 66 protein spots in human plasma and found that seven of them showed altered changes in schizophrenia patients, as compared to healthy controls, which mainly were acute phase proteins (APPs). Among these APPs, haptoglobin alpha2 chain (p < 0.001), haptoglobin beta chain (p < 0.001), alpha1-antitrypsin (p = 0.001), and complement factor B precursor (p = 0.022) showed overexpression in schizophrenia patients, whereas apolipoprotein A-I (p = 0.034) and transthyretin (p = 0.035) were found to be significantly decreased in patients. In addition, the expression of apolipoprotein A-IV (p = 0.018) was significantly up-regulated in schizophrenia patients, as compared to controls. We also found these APP genes, which were differentially expressed in this study, overlap in the schizophrenia susceptibility loci. Our findings further support the hypothesis that the inflammatory response system is linked to the pathophysiology of schizophrenia. Show less
ApoAV, a newly discovered apolipoprotein, plays a key role in human triglyceride homeostasis; however, the structure-function correlation of apoAV is not clearly understood. To explore the relationshi Show more
ApoAV, a newly discovered apolipoprotein, plays a key role in human triglyceride homeostasis; however, the structure-function correlation of apoAV is not clearly understood. To explore the relationship, wild type and six deletion mutants, that is (AV (Delta(1-51)), AV (Delta(51-128)), AV (Delta(132-188)), AV (Delta(192-238)), AV (Delta(246-299)), AV (Delta(301-343))), of human apoAV expressed in Escherichia coli were studied. All the deleted regions together encompass almost the entire 343 amino acid sequence of wild type apoAV. Circular dichroism spectroscopy showed that the alpha helical content of lipid-free wild type apoAV was 46%. In comparison with wild type apoAV, AV (Delta(192-238)) and AV (Delta(301-343)) displayed significantly decreased lipid binding activities, confirming the importance of these two regions in lipid binding function of apoAV. While, the LPL activation function of apoAV remarkably impaired after deletion of residues 192-238. These findings suggested that the domain (192-238) is absolutely necessary for apoAV in lipid binding and lipoprotein lipase activation. Show less
Amanda H McDaniel, Xia Li, Michael G Tordoff+2 more · 2006 · Mammalian genome : official journal of the International Mammalian Genome Society · Springer · added 2026-04-24
To identify the gene or genes on mouse Chromosome 9 that contribute to strain differences in fatness, we conducted an expanded mapping analysis to better define the region where suggestive linkage was Show more
To identify the gene or genes on mouse Chromosome 9 that contribute to strain differences in fatness, we conducted an expanded mapping analysis to better define the region where suggestive linkage was found, using the F(2 )generation of an intercross between the C57BL/6ByJ and 129P3/J mouse strains. Six traits were studied: the summed weight of two adipose depots, the weight of each depot, analyzed individually (the gonadal and retroperitoneal depot), and the weight of each depot (summed and individual) relative to body size. We found significant linkage (LOD = 4.6) that accounted for the relative weight of the summed adipose depots, and another for the relative weight of the gonadal (LOD = 5.3) but not retroperitoneal (LOD = 0.9) adipose depot. This linkage is near marker rs30280752 (61.1 Mb, Build 34) and probably is equivalent to the quantitative trait locus (QTL) Adip5. Because the causal gene is unknown, we identified and evaluated several candidates within the confidence interval with functional significance to the body fatness phenotype (Il18, Acat1, Cyp19a1, Crabp1, Man2c1, Neil1, Mpi1, Csk, Lsm16, Adpgk, Bbs4, Hexa, Thsd4, Dpp8, Anxa2, and Lipc). We conclude that the Adip5 locus is specific to the gonadal adipose depot and that a gene or genes near the linkage peak may account for this QTL. Show less
Both G1 and mitotic cyclins have been implicated in regulating Candida albicans filamentous growth. We have investigated the functions of Grr1 whose orthologue in Saccharomyces cerevisiae is known to Show more
Both G1 and mitotic cyclins have been implicated in regulating Candida albicans filamentous growth. We have investigated the functions of Grr1 whose orthologue in Saccharomyces cerevisiae is known to mediate ubiquitin-dependent degradation of the G1 cyclins Cln1 and Cln2. Here, we report that deleting C. albicans GRR1 causes significant stabilization of two G1 cyclins Ccn1 and Cln3 and pseudohyphal growth. grr1Delta cells are highly heterogeneous in length and many of them fail to separate after cytokinesis. Interestingly, some isolated rod-like G1 cells of similar sizes are present in the grr1Delta culture. Time-lapse microscopy revealed that the rod-shaped G1 cells first grew exclusively in width before budding and then the bud grew exclusively by apical extension until after cytokinesis, yielding rod-like daughter cells. Consistently, actin patches persistently localize to the bud tip until around the time of cytokinesis. Despite the pseudohyphal phenotype, grr1Delta cells respond normally to hyphal induction. Hyperphosphorylated Cln3 isoforms accumulate in grr1Delta cells, indicating that Grr1 selectively mediates their degradation in wild-type cells. grr1Delta pseudohyphal growth requires neither Hgc1 nor Swel, two important regulators of cell morphogenesis. Furthermore, the cellular level of Hof1, a protein having a role in cytokinesis, is also significantly increased in grr1Delta cells. Show less
In spite of recent evidence showing the importance of DBY (DEAD-box RNA helicase Y) in spermatogenesis in human, the biologic role of its homolog Dby (also known as Ddx3y) in the mouse is less clear. Show more
In spite of recent evidence showing the importance of DBY (DEAD-box RNA helicase Y) in spermatogenesis in human, the biologic role of its homolog Dby (also known as Ddx3y) in the mouse is less clear. The present study aims at characterizing the molecular structure of Dby and comparing its expression with its X- and autosome-linked homologs in embryonic gonads and developing germ cells in mice. Molecular cloning by rapid amplification of 3'-cDNA ends showed that the Dby gene in the mouse gives rise to 2 transcripts that differ only in the length of the 3'-untranslated region as a consequence of the use of alternative polyadenylation signals. Measurement by quantitative real-time polymerase chain reaction showed that both transcripts were ubiquitously expressed and were present in male germ cells and Sertoli cells. They were more abundant in type A spermatogonia compared with pachytene spermatocytes and round spermatids. Expression of Dby in the embryonic gonad increased from day 10.5 and reached a peak at day 17.5. The expression level of Dby decreased after birth and remained low in adult male gonads. Although the level of expression of Dby was much lower than its X chromosome homolog, Ddx3 (also known as Ddx3x) in all samples examined, the pattern of expression of the 2 genes was comparable. In contrast, their autosomal homolog, D1Pas1(also known as PL10), was predominantly expressed in pachytene spermatocytes and round spermatids. This result is in accord with meiotic sex chromosome inactivation in that Dby and Ddx are replaced in pachytene spermatocytes by their autosomal retroposon. These observations indicate that unlike DBY in humans, the role of Dby in spermatogenesis is less obvious in the mouse and its biologic activity may be replaced by that of Ddx3 and D1Pas1. Show less
Delta-like 4 (Dll4), a membrane-bound ligand for Notch1 and Notch4, is selectively expressed in the developing endothelium and in some tumor endothelium, and it is induced by vascular endothelial grow Show more
Delta-like 4 (Dll4), a membrane-bound ligand for Notch1 and Notch4, is selectively expressed in the developing endothelium and in some tumor endothelium, and it is induced by vascular endothelial growth factor (VEGF)-A and hypoxia. Gene targeting studies have shown that Dll4 is required for normal embryonic vascular remodeling, but the mechanisms underlying Dll4 regulatory functions are currently not defined. In this study, we generated primary human endothelial cells that overexpress Dll4 protein to study Dll4 function and mechanism of action. Human umbilical vein endothelial cells retrovirally transduced with Dll4 displayed reduced proliferative and migratory responses selectively to VEGF-A. Expression of VEGF receptor-2, the principal signaling receptor for VEGF-A in endothelial cells, and coreceptor neuropilin-1 was significantly decreased in Dll4-transduced endothelial cells. Consistent with Dll4 signaling through Notch, expression of HEY2, one of the transcription factors that mediates Notch function, was significantly induced in Dll4-overexpressing endothelial cells. The gamma-secretase inhibitor L-685458 significantly reconstituted endothelial cell proliferation inhibited by immobilized extracellular Dll4 and reconstituted VEGFR2 expression in Dll4-overexpressing endothelial cells. These results identify the Notch ligand Dll4 as a selective inhibitor of VEGF-A biologic activities down-regulating 2 VEGF receptors expressed on endothelial cells and raise the possibility that Dll4 may be exploited therapeutically to modulate angiogenesis. Show less
LINGO-1 is a CNS-specific protein and a functional component of the NgR1/p75/LINGO-1 and NgR1/TAJ(TROY)/LINGO-1 signaling complexes that mediate inhibition of axonal outgrowth. These receptor complexe Show more
LINGO-1 is a CNS-specific protein and a functional component of the NgR1/p75/LINGO-1 and NgR1/TAJ(TROY)/LINGO-1 signaling complexes that mediate inhibition of axonal outgrowth. These receptor complexes mediate the axonal growth inhibitory effects of Nogo, myelin-associated glycoprotein (MAG) and oligodendrocyte-myelin glycoprotein (OMgp) via RhoA activation. Soluble LINGO-1 (LINGO-1-Fc), which acts as an antagonist of these pathways by blocking LINGO-1 binding to NgR1, was administered to rats after dorsal or lateral hemisection of the spinal cord. LINGO-1-Fc treatment significantly improved functional recovery, promoted axonal sprouting and decreased RhoA activation and increased oligodendrocyte and neuronal survival after either rubrospinal or corticospinal tract transection. These experiments demonstrate an important role for LINGO-1 in modulating axonal outgrowth in vivo and that treatment with LINGO-1-Fc can significantly enhance recovery after spinal cord injury. Show less
Leucine-rich repeats (LRR) are protein-protein interaction domains (20-29 amino acid residues in length) found in proteins with diverse structure and functions. We note here an emerging group of centr Show more
Leucine-rich repeats (LRR) are protein-protein interaction domains (20-29 amino acid residues in length) found in proteins with diverse structure and functions. We note here an emerging group of central nervous system-enriched, type I surface proteins with an ectodomain containing LRR repeats and motifs found in cell adhesion molecules. Members of this group include the Amphoterin-induced gene and ORF-1 (AMIGO-1), LRR and Ig domain containing Nogo Receptor interacting protein I (LINGO-1) and the netrin-G1 ligand NGL-1. The above proteins carry, in addition to the LRR repeats, an immunoglobin (Ig)-like segment in their ectodomain. Two other related families of molecules, the NLRRs and the FLRTs, have in addition, a fibronectin type III repeat. The LRR domain distinguishes these molecules from the more extensively studied Ig-like family of cell adhesion molecules, and the transmembrane domain differentiate them from the family of secreted extracellular proteoglycans with LRRs. Functionally, many members of this group of proteins could modulate neurite outgrowth of neurons, at least in vitro. LINGO-1, initially discovered as a component of the Nogo-66 receptor complex which inhibits neurite growth, also regulates oligodendrocyte differentiation and myelination. Current knowledge and recent findings pertaining to the functions of this interesting group of proteins in the nervous system are discussed. Show less
Human protein kinases make up a large superfamily of homologous proteins, which are related by virtue of their kinase domains (also known as catalytic domains). Here we report the cloning and characte Show more
Human protein kinases make up a large superfamily of homologous proteins, which are related by virtue of their kinase domains (also known as catalytic domains). Here we report the cloning and characterization of a novel human MAST4 (microtubule associated serine/threonine kinase family member 4) gene, which locates on human chromosome 5q13. The MAST4 cDNA is 7587 base pairs in length and encodes a putative protein of 2435 amino acids which contains a serine/threonine kinase domain and a PDZ domain. MAST4 protein has 64%, 63%, 59% and 39% identical aminoacid residues with MAST1, MAST2, MAST3 and MASTL respectively. RT-PCR analysis revealed relatively high expression level of MAST4 in most normal human tissues, with an exception of in testis, small intestine, colon and peripheral blood leukocyte. Show less
In Akita and OVE26 mice, two genetic models of type 1 diabetes, diabetic nephropathy is characterized by mesangial expansion and loss of podocytes, resulting in glomerulosclerosis and proteinuria, and Show more
In Akita and OVE26 mice, two genetic models of type 1 diabetes, diabetic nephropathy is characterized by mesangial expansion and loss of podocytes, resulting in glomerulosclerosis and proteinuria, and is associated with increased expression of profibrotic growth factors, proinflammatory cytokines, and increased oxidative stress. We have also found significant increases in renal triglyceride and cholesterol content. The increase in renal triglyceride content is associated with 1) increased expression of sterol regulatory element-binding protein (SREBP)-1c and carbohydrate response element-binding protein (ChREBP), which collectively results in increased fatty acid synthesis, 2) decreased expression of peroxisome proliferator-activated receptor (PPAR)-alpha and -delta, which results in decreased fatty acid oxidation, and 3) decreased expression of farnesoid X receptor (FXR) and small heterodimer partner (SHP). The increase in cholesterol content is associated with 1) increased expression of SREBP-2 and 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase, which results in increased cholesterol synthesis, and 2) decreased expression of liver X receptor (LXR)-alpha, LXR-beta, and ATP-binding cassette transporter-1, which results in decreased cholesterol efflux. Our results indicate that in type 1 diabetes, there is altered renal lipid metabolism favoring net accumulation of triglycerides and cholesterol, which are driven by increases in SREBP-1, ChREBP, and SREBP-2 and decreases in FXR, LXR-alpha, and LXR-beta, which may also play a role in the increased expression of profibrotic growth hormones, proinflammatory cytokines, and oxidative stress. Show less
We report here a novel mechanism for glucose-mediated activation of carbohydrate response element binding protein (ChREBP), a basic helix-loop-helix/leucine zipper (bHLH/ZIP) transcription factor of M Show more
We report here a novel mechanism for glucose-mediated activation of carbohydrate response element binding protein (ChREBP), a basic helix-loop-helix/leucine zipper (bHLH/ZIP) transcription factor of Mondo family that binds to carbohydrate response element in the promoter of some glucose-regulated genes and activates their expression upon glucose stimulation. Structure-function analysis of ChREBP in a highly glucose-sensitive system using GAL4-ChREBP fusion constructs revealed a glucose-sensing module (GSM) that mediates glucose responsiveness of ChREBP. GSM is conserved among Mondo family members; MondoA, a mammalian paralog of unknown function, and the GSM region of a Drosophila homolog were also found to be glucose responsive. GSM is composed of a low-glucose inhibitory domain (LID) and a glucose-response activation conserved element (GRACE). We have identified a new mechanism accounting for glucose responsiveness of ChREBP that involves specific inhibition of the transactivation activity of GRACE by LID under low glucose concentration and reversal of this inhibition by glucose in an orientation-sensitive manner. The intramolecular inhibition and its release by glucose is a regulatory mechanism that is independent of changes of subcellular localization or DNA binding activity, events that also appear to be involved in glucose responsiveness. This evolutionally conserved mechanism may play an essential role in glucose-responsive gene regulation. Show less
To compare the gene mutation between Chinese patients with familial and sporadic hypertrophic cardiomyopathy (HCM). Peripheral blood samples were collected from 36 patients with familial HCM (FHCM) an Show more
To compare the gene mutation between Chinese patients with familial and sporadic hypertrophic cardiomyopathy (HCM). Peripheral blood samples were collected from 36 patients with familial HCM (FHCM) and 50 patients with sporadic HCM (SHCM), all un-related and from different provinces of China. PCR was used to amplify the 26 protein-coding axons of beta-myosin heavy chain (MYH7), 16 exons for cardiac troponin T (TNNT2), and 38 exons for cardiac myosin-binding protein C (MYBPC3). The amplified products were sequenced and compared with the standard sequence in the genBank so as to determine the potential mutation sites. (1) 13 of the 36 FHCM patients (36.1%) harbored 3 different mutations in MYH7 gene: Arg663His in exon18, Glu924Lys in exon 23, and Ile736Thr in exon 20. Of the 50 SHCM patients, only 1 (2%) harbored MYH7 gene missence mutation: Ile736Thr located in exon 20. (2) TNNT2 was not identified in all SHCM patients and FHCM patients. (3) MYBPC3 was not identified in all SHCM patients. Four FHCM patients harbored 2 different mutations: Arg502Trp in exon 18 and Arg346fs in exon 13 respectively. MYH7 and MYBPC3 may be the dominant disease-causing genes in Chinese familial HCM patients; however the mutation rate of MYH7 and MYBPC3 genes is significantly lower in the SHCM patients compared with the FHCM patients. TNNT2 seems not the predominant disease-causing gene in all Chinese patients with HCM. Show less
The aim of this study was to screen the disease-causing gene mutations and investigate the genotype-phenotype correlation in 10 Chinese pedigrees with familial hypertrophic cardiomyopathy (HCM). There Show more
The aim of this study was to screen the disease-causing gene mutations and investigate the genotype-phenotype correlation in 10 Chinese pedigrees with familial hypertrophic cardiomyopathy (HCM). There are 91 family members from these 10 pedigrees and 5 members were normal mutated carriers, 23 members were HCM patients (14 male) aged from 1.5 to 73 years old. The functional regions of myosin heavy chain gene (MYH7), cardiac myosin-binding protein C (MYBPC3) and cardiac troponin T gene (TNNT2) were screened with PCR and direct sequencing technique. Clinical information from all patients was also evaluated in regard to the genotype. Mutations were found in 5 out of 10 pedigrees. Mutations in MYH7 (Arg663His, Glu924Lys and Ile736Thr) were found in 3 pedigrees and 3 patients from these pedigrees suffered sudden death at age 20-48 years old during sport. Mutations in MYBPC3 were found in 2 pedigrees, 1 with complex mutation (Arg502Trp and splicing mutation IVS27 + 12C > T) and 1 with novel frame shift mutation (Gly347fs) and the latter pedigree has sudden death history. No mutation was identified in TNNT2. Although the Han Chinese is a relatively homogeneous ethnic group, different HCM gene mutations were responsible for familiar HCM suggesting the heterogeneity nature of the disease-causing genes and HCM MYH7 mutations are associated with a higher risk of sudden death in this cohort. Furthermore, identical mutation might result in different phenotypes suggesting that multiple factors might be involved in the pathogenesis of familiar HCM. Show less
Sigma receptors (sigmaRs) are nonopioid, nonphencyclidine binding sites with robust neuroprotective properties. Type 1 sigmaR1 (sigmaR1) is expressed in brain oligodendrocytes, but its expression and Show more
Sigma receptors (sigmaRs) are nonopioid, nonphencyclidine binding sites with robust neuroprotective properties. Type 1 sigmaR1 (sigmaR1) is expressed in brain oligodendrocytes, but its expression and binding capacity have not been analyzed in retinal glial cells. This study examined the expression, subcellular localization, binding activity, and regulation of sigmaR1 in retinal Müller cells. Primary mouse Müller cells (MCs) were analyzed by RT-PCR, immunoblotting, and immunocytochemistry for the expression of sigmaR1, and data were compared with those of the rat Müller cell line (rMC-1) and the rat ganglion cell line (RGC-5). Confocal microscopy was used to determine the subcellular sigmaR1 location in primary mouse MCs. Membranes prepared from these cells were used for binding assays with [3H]-pentazocine (PTZ). The kinetics of binding, the ability of various sigmaR1 ligands to compete with sigmaR1 binding, and the effects of donated nitric oxide (NO) and reactive oxygen species (ROS) on binding were examined. sigmaR1 is expressed in primary mouse MCs and is localized to the nuclear and endoplasmic reticulum membranes. Binding assays showed that in primary mouse MCs, rMC-1, and RGC-5, the binding of PTZ was saturable. [3H]-PTZ bound with high affinity in RGC-5 and rMC-1 cells, and the binding was similarly robust in primary mouse MCs. Competition studies showed marked inhibition of [3H]-PTZ binding in the presence of sigmaR1-specific ligands. Incubation of cells with NO and ROS donors markedly increased sigmaR1 binding activity. MCs express sigmaR1 and demonstrate robust sigmaR1 binding activity, which is inhibited by sigmaR1 ligands and is stimulated during oxidative stress. The potential of Müller cells to bind sigmaR1 ligands may prove beneficial in retinal degenerative diseases such as diabetic retinopathy. Show less
Yi-bo Tang, Ping Sun, Dong-ping Guo+3 more · 2005 · Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics · added 2026-04-24
To investigate the relationship between apolipoprotein A5(apoA5) - 1131T > C polymorphism and the susceptibility of coronary artery disease (CAD) in Chinese. The restriction fragment length polymorphi Show more
To investigate the relationship between apolipoprotein A5(apoA5) - 1131T > C polymorphism and the susceptibility of coronary artery disease (CAD) in Chinese. The restriction fragment length polymorphism of apoA5 gene - 1131T > C was studied using PCR in a case-control study which enrolled 235 patients with CAD diagnosed by angiography and 262 healthy controls from Jiangsu province. The frequencies of T, C allele were 59.57%ì40.43% and 65.65%, 34.35% in CAD group and control group respectively. There was statistically significant difference in allele frequencies between CAD group and control group (P < 0.05). The susceptibility to CAD for the CC genotype was much higher than that for wild type TT (OR = 1.872, 95% CI = 1.039 - 3.376, P = 0.037), even after the use of Logistic regression models (OR = 2.285, 95% CI = 1.222 - 4.274, P = 0.012). In control group, there was significant difference in TG levels among different genotypes, the C allele carriers had higher serum TG concentration (P = 0.007). apoA5 - 1131T > C polymorphism is associated with an increased risk of CAD and is also in strong association with serum TG levels. Show less
To investigate the association between the -1131T/C and 56C/G polymorphism in the APOA5 gene as well as the -482C/T in the APOC3 gene and susceptibility to coronary artery disease (CAD) in a Chinese H Show more
To investigate the association between the -1131T/C and 56C/G polymorphism in the APOA5 gene as well as the -482C/T in the APOC3 gene and susceptibility to coronary artery disease (CAD) in a Chinese Han population. Using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and polyacrylamide gel electrophoresis (PAGE) methods, we analyzed the genotypes in 312 CAD patients diagnosed by angiography and 317 healthy controls. The levels of serum lipid profiles were also studied by biochemical methods. The frequency of the APOA5 -1131 C allele in CAD patients was significantly higher than that of the control group (39.9% vs. 33.3%, P = 0.02). Compared with the wild type TT, CC homozygotes had a significantly increased CAD risk (OR = 1.93 and OR = 1.80 using unadjusted and adjusted logistic regression models, respectively). This association still existed after adjustment for the APOC3-482 variant. The APOA5-1131C allele also showed a correlation with increasing plasma TG levels (P < 0.01). The APOA5-1131T/C polymorphism but not APOC3-482C/T might contribute to an increased risk of CAD among Chinese accompanied by an elevation of serum TG levels; this effect was found to be independent of the APOC3-482C/T variant. Show less
The recently discovered apolipoprotein A5 ( APOA5 ) gene has been shown to be important in determining plasma triglyceride levels, a major cardiovascular disease risk factor. We searched for possible Show more
The recently discovered apolipoprotein A5 ( APOA5 ) gene has been shown to be important in determining plasma triglyceride levels, a major cardiovascular disease risk factor. We searched for possible associations of the APOA5 gene polymorphisms S19W and -1131T>C with coronary heart disease (CHD) in a Chinese population. A total of 483 Chinese CHD patients and 502 control non-CHD subjects were genotyped by polymerase chain reaction-restriction fragment length polymorphism for these 2 single nucleotide polymorphisms. We found that the minor allele 19W was observed only in CHD patients and not in controls, with allelic frequencies of 0.047 and 0.000, respectively ( P < .000001), and the minor allele -1131C was significantly higher in CHD patients than in controls (0.391 vs 0.299, P < .0001). These results suggest that both the S19W and -1131T>C variations in the APOA5 gene are associated with the CHD and appear to be 2 genetic risk factors for CHD susceptibility in Chinese. Moreover, we found that triglyceride levels were significantly higher in -1131C carriers than in -1131T subjects of the control group and that high-density-lipoprotein cholesterol was decreased in -1131C carriers among CHD patients. Show less
In order to clarify the relationship of apolipoprotein CIII (APOC3) polymorphism and sporadic Alzheimer's disease (AD) in Chinese, 165 sporadic AD patients and 174 age-matched elderly individuals were Show more
In order to clarify the relationship of apolipoprotein CIII (APOC3) polymorphism and sporadic Alzheimer's disease (AD) in Chinese, 165 sporadic AD patients and 174 age-matched elderly individuals were genotyped for the APOC3 SstI and apolipoprotein E (APOE) HhaI polymorphisms. As the result, the APOC3 3017G allele was found to be associated with AD in APOE epsilon4 allele noncarriers (chi2=4.433, P=0.035), and the risk estimate of allele C versus G resulted in an OR of 1.56 (95% CI: 1.03-2.37), although in total no significant differences of allelic or genotypic frequencies between patients and controls were found. Assessment of interaction between APOE epsilon4 and APOC3 3017G status presented an adjusted odds ratio of 0.62 (95% CI: 0.37-1.03) with a borderline significant P-value (P=0.066). Therefore, we conclude that the rare APOC3 G allele may offer some protection against the development of sporadic AD in APOE epsilon4 noncarriers in Chinese. Show less
Several independent population studies have reported that the apolipoprotein C3 (APOC3) Sst I polymorphism in apolipoprotein (apo) A1 /C3/A4/A5 gene cluster is associated with Hypertriglyceridaemia (H Show more
Several independent population studies have reported that the apolipoprotein C3 (APOC3) Sst I polymorphism in apolipoprotein (apo) A1 /C3/A4/A5 gene cluster is associated with Hypertriglyceridaemia (HTG). HTG is a known risk factor for coronary atherosclerotic heart disease(CHD)and type II diabetes mellitus (non-insulin-dependent diabetes, NIDDM). The aim of this study is to investigate the association between the APOC3 gene Sst I polymorphism and the hypertriglyceridaemia in CHD and NIDDM in Chinese population. The genotype and allele frequencies of APOC3 Sst I polymorphism (S1/S2) were analyzed by PCR-restriction fragment length polymorphism in 267 CHD patients, 246 NIDDM patients and 491 unrelated healthy control individuals. The frequencies of minor allele 52 in CHD group, NIDDM group and control group were 0.301, 0.307 and 0.286, respectively. Compared with controls, there was no significant difference in distribution of genotype and allele frequencies of Sst I polymorphic site in CHD patients and NIDDM patients, respectively. However, the frequency of S1 S2 genotype in the HTG subgroup was significantly higher than that of the normal triglyceridaemia subgroup (NTG) in CHD patients (0.542 > 0.357, chi2 = 8.77, P = 0.0124). In NIDDM patients, the frequency of S2 S2 genotype in the HTG subgroup was significantly high, compared with that in the NTG subgroup (0.200 > 0.055, chi2 = 20.21, P = 0.0000), and there was significantly difference in the distribution of allele frequencies in subgroups of NTG and HTG (chi2 = 19.86, P = 0.0000). The level of triglyceride (TG) in S1 S2 genotype patients of CHD group were higher than that of S1 S1 genotype patients (P = 0.036). In NIDDM and controls groups, S2 S2 genotype individuals exhibited a significant increase in plasma TG concentrations, respectively compared with S1 S1 and S1 S2 genotype individuals of each group (P < 0.01). The minor allele S2, which was associated with both CHD with HTG and NIDDM with HTG and may contribute to the susceptibility of hypertriglyceridemia in CHD and NIDDM patients, may be one of the genetic predispositions to both CHD with HTG and NIDDM with HTG in Chinese population. Show less
Signalling by the Wnt family of secreted lipoproteins has essential functions in development and disease. The canonical Wnt/beta-catenin pathway requires a single-span transmembrane receptor, low-dens Show more
Signalling by the Wnt family of secreted lipoproteins has essential functions in development and disease. The canonical Wnt/beta-catenin pathway requires a single-span transmembrane receptor, low-density lipoprotein (LDL)-receptor-related protein 6 (LRP6), whose phosphorylation at multiple PPPSP motifs is induced upon stimulation by Wnt and is critical for signal transduction. The kinase responsible for LRP6 phosphorylation has not been identified. Here we provide biochemical and genetic evidence for a 'dual-kinase' mechanism for LRP6 phosphorylation and activation. Glycogen synthase kinase 3 (GSK3), which is known for its inhibitory role in Wnt signalling through the promotion of beta-catenin phosphorylation and degradation, mediates the phosphorylation and activation of LRP6. We show that Wnt induces sequential phosphorylation of LRP6 by GSK3 and casein kinase 1, and this dual phosphorylation promotes the engagement of LRP6 with the scaffolding protein Axin. We show further that a membrane-associated form of GSK3, in contrast with cytosolic GSK3, stimulates Wnt signalling and Xenopus axis duplication. Our results identify two key kinases mediating Wnt co-receptor activation, reveal an unexpected and intricate logic of Wnt/beta-catenin signalling, and illustrate GSK3 as a genuine switch that dictates both on and off states of a pivotal regulatory pathway. Show less
SP100 was first identified as a nuclear autoimmune antigen and is a constituent of the nuclear body. SP100 interacts with the ETS1 transcription factor, and we have previously shown that SP100 reduces Show more
SP100 was first identified as a nuclear autoimmune antigen and is a constituent of the nuclear body. SP100 interacts with the ETS1 transcription factor, and we have previously shown that SP100 reduces ETS1-DNA binding and inhibits ETS1 transcriptional activity on the MMP1 and uPA promoters. We now demonstrate that SP100 expression is upregulated by interferons, which have been shown to be antiangiogenic, in primary endothelial cells. As ETS1 is functionally important in promoting angiogenesis, we tested the hypothesis that ETS1 activity is negatively modulated by SP100 in endothelial cells. SP100 directly antagonizes ETS1-mediated morphological changes in human umbilical vein endothelial cell (HUVEC) network formation and reduces HUVEC migration and invasion. To further understand the functional relationship between ETS1 and SP100, cDNA microarray analysis was utilized to assess reprogramming of gene expression by ETS1 and SP100. A subset of the differentially regulated genes, including heat-shock proteins (HSPs) H11, HSPA1L, HSPA6, HSPA8, HSPE1 and AXIN1, BRCA1, CD14, CTGF (connective tissue growth factor), GABRE (gamma-aminobutyric acid A receptor epsilon), ICAM1, SNAI1, SRD5A1 (steroid-5-alpha-reductase 1) and THY1, were validated by real-time PCR and a majority showed reciprocal expression in response to ETS1 and SP100. Interestingly, genes that are negatively regulated by ETS1 and upregulated by SP100 have antimigratory or antiangiogenic properties. Collectively, these data indicate that SP100 negatively modulates ETS1-dependent downstream biological processes. Show less
A gene coding a novel isoform of carbamyl phosphate synthetase I (CPS1) was cloned from a human testicular library. As shown by cDNA microarray hybridization, this gene was expressed at a higher level Show more
A gene coding a novel isoform of carbamyl phosphate synthetase I (CPS1) was cloned from a human testicular library. As shown by cDNA microarray hybridization, this gene was expressed at a higher level in human adult testes than in fetal testes. The full length of its cDNA was 3831 bp, with a 3149 bp open reading frame, encoding a 1050-amino-acid protein. The cDNA sequence was deposited in the GenBank (AY317138). Sequence analysis showed that it was homologous to the human CPS1 gene. The putative protein contained functional domains composing the intact large subunit of carbamoyl phosphate synthetase, thus indicated it has the capability of arginine biosynthesis. A multiple tissue expression profile showed high expression of this gene in human testis, suggesting the novel alternative splicing form of CPS1 may be correlated with human spermatogenesis. Show less
Epigenetic modifications play an important role in human cancer. One such modification, histone methylation, contributes to human cancer through deregulation of cancer-relevant genes. The yeast Dot1 a Show more
Epigenetic modifications play an important role in human cancer. One such modification, histone methylation, contributes to human cancer through deregulation of cancer-relevant genes. The yeast Dot1 and its human counterpart, hDOT1L, methylate lysine 79 located within the globular domain of histone H3. Here we report that hDOT1L interacts with AF10, an MLL (mixed lineage leukemia) fusion partner involved in acute myeloid leukemia, through the OM-LZ region of AF10 required for MLL-AF10-mediated leukemogenesis. We demonstrate that direct fusion of hDOT1L to MLL results in leukemic transformation in an hDOT1L methyltransferase activity-dependent manner. Transformation by MLL-hDOT1L and MLL-AF10 results in upregulation of a number of leukemia-relevant genes, such as Hoxa9, concomitant with hypermethylation of H3-K79. Our studies thus establish that mistargeting of hDOT1L to Hoxa9 plays an important role in MLL-AF10-mediated leukemogenesis and suggests that the enzymatic activity of hDOT1L may provide a potential target for therapeutic intervention. Show less
To explore the disease-causing gene mutation in Chinese with hypertrophic cardiomyopathy (HCM). The peripheral venous blood samples were collected from 5 HCM families without consanguinity, including Show more
To explore the disease-causing gene mutation in Chinese with hypertrophic cardiomyopathy (HCM). The peripheral venous blood samples were collected from 5 HCM families without consanguinity, including 5 probands, 2 males and 3 females, 28 sporadic HCM patients, 18 males and 10 females, and 80 healthy controls. The exons in the functional regions of cardiac myosin-binding protein C (MYBPC3) were amplified with PCR and the amplified products were sequenced. A frame shift mutation-Arg346fs mutation in exon 13, the first mutation identified in Chinese-was discovered in one family with HCM. However, the members of the same HCM family with the Arg346fs mutation showed differences in phenotype and prognosis. Cardiac myosin-binding protein C (MYBPC3) may be one of the main disease-causing genes. The heterogeneity of phenotype suggests that multiple factors may be involved in the pathogenesis. Show less
There are more than 1 million patients with hypertrophic cardiomyopathy (HCM) in China, but the genetic basis is presently unknown. We investigated 100 independent patients with HCM (proband 51, spora Show more
There are more than 1 million patients with hypertrophic cardiomyopathy (HCM) in China, but the genetic basis is presently unknown. We investigated 100 independent patients with HCM (proband 51, sporadic 49) by sequencing the three most frequent HCM-causing genes (MYH7, MYBPC3, TNNT2). Thirty-four patients (34%) carried 25 types of mutations in the selected genes, most (14/25) were newly identified. MYH7 and MYBPC3 accounted for 41% and 18% of the familial HCM, respectively. TNNT2 mutations only caused 2% of the familial HCM. These results suggested that MYH7 and MYBPC3 were the predominant genes responsible for HCM, and TNNT2 mutation less proportionally contributed to Chinese HCM. MYH7 mutations caused HCM at younger age, more frequent syncope and ECG abnormalities compared with MYBPC3 mutations. The patients carrying R663C, Q734P, E930K in MYH7 and R130C in TNNT2 expressed malignant phenotype. R403Q in MYH7, the most common hot and malignant mutation in Caucasians, was not identified in Chinese. We confirmed the diversity of mutation profile in different populations and suggest that a global registry of HCM mutations and their phenotypes is necessary to correlate genotype with phenotype. Show less
The expression and function of the glutamine transporters ATA1 and ATA2 (isoforms of system A), SN1 and SN2 (isoforms of system N), and LAT1 and LAT2 (isoforms of system L) were investigated in Müller Show more
The expression and function of the glutamine transporters ATA1 and ATA2 (isoforms of system A), SN1 and SN2 (isoforms of system N), and LAT1 and LAT2 (isoforms of system L) were investigated in Müller cells in a rat Müller cell line (rMC1) and primary cultures of mouse Müller cells. Glutamine uptake in rMC1 cells and primary Müller cells was measured. The relative contributions of various transport systems to glutamine uptake were determined based on the differential substrate specificities and Na(+) dependence of individual transport systems. RT-PCR was used to analyze the expression of transporter-specific mRNAs. Three different transport systems participated in glutamine uptake in rMC1 cells: system L (Na(+)-independent), system A (Na(+)-dependent and alpha-(methylamino)isobutyric acid [MeAIB]-sensitive), and system N (Na(+)-dependent and MeAIB-insensitive). System N was the principal contributor (approximately 70%); the contributions of systems A and L were relatively lesser (20% and <10%, respectively). The functional features of Na(+)-dependent and MeAIB-insensitive glutamine uptake were similar to the known characteristics of clones of SN1 and SN2. Glutamine uptake in primary Müller cells behaved in a manner similar to that in rMC1 cells. mRNA transcripts specific for ATA1, ATA2, SN1, SN2, LAT1, and LAT2 were expressed in Müller cells. System N (SN1 as well as SN2) is responsible for most of the glutamine uptake in Müller cells. Because system N is capable of mediating the release of glutamine from the cells, its abundant expression in Müller cells is of importance in the handling of glutamine in the retina. Show less