👤 Jen-Zen Chuang

Alzheimer disease (AD) pathology may begin decades before symptoms. Genetic factors, such as APOE ε4 carrier status and polygenic risk scores (PRS), influence AD risk, but their roles in cognitive decline among Asian populations remain unclear. To evaluate whether APOE ε4 carrier status and a non-APOE polygenic risk score (PRS_ADnapoe) are associated with age-related cognitive decline in community-dwelling older adults in Taiwan. This prospective cohort study used data from 2 assessment waves of the Healthy Aging Longitudinal Study in Taiwan, spanning 2009 to 2019. Participants were aged 55 years and older and had both genetic data and Mini-Mental State Examination (MMSE) scores. Data analyses were conducted from August to December 2025. APOE ε4 carrier status (noncarrier, heterozygote, homozygote) and PRS_ADnapoe score, derived from genome-wide association summary statistics excluding APOE variants. The primary outcome was change in MMSE scores, which were assessed cross-sectionally and longitudinally, modeled with mixed-effects regression accounting for age-related effects and covariates including sex, education, smoking, and population structure. Among 4392 participants (mean [SD] age, 68.2 [7.8] years; 2359 [53.7%] women), 723 (16.5%) were APOE ε4 heterozygotes and 33 (0.8%) were APOE ε4 homozygotes. Over a mean (SD) follow-up of 6.3 (0.9) years, the mean (SD) annual MMSE decline was -0.2 (0.5). APOE ε4 carriage was associated with a significantly steeper quadratic age-associated decline in MMSE scores compared with noncarriers (estimate, -0.005; SE, 0.001; P = .001). This association was strongest among homozygotes (estimate, -0.017; SE, 0.008; P = .03), with MMSE trajectories diverging after approximately age 70 years. In contrast, PRS_ADnapoe scores were not associated with MMSE decline. Sensitivity analyses restricted to participants with 2-wave data and adjusted with inverse probability of censoring weighting confirmed these findings. In this cohort study of middle-aged and older adults in Taiwan, APOE ε4 carriage, particularly homozygosity, was associated with accelerated age-related cognitive decline detectable after age 70 years, whereas non-APOE polygenic risk was not associated with cognitive decline over the current follow-up. These results highlight the potential utility of early genetic risk awareness and support consideration of targeted preventive strategies for APOE ε4 carriers. Show less

Alzheimer's disease (AD), particularly its sporadic form (SAD, 95 % AD patients), is strongly associated with the apolipoprotein E4 (ApoE4) genotype and characterized by oxidative stress, iron dysregulation, and increased susceptibility to ferroptosis. Lithium, a well-established neuroprotective agent, has shown potential to mitigate several pathological mechanisms in AD, including ferroptosis. This study investigates the therapeutic potential of lithium chloride in human induced pluripotent stem cells (iPSCs) derived from a SAD patient with ApoE4/E4 genotype and compared effects with those of isogenic gene-edited ApoE3/E3 control. Lithium treatment significantly improved cell viability in ApoE4/E4 iPSCs. It also reversed key ferroptosis phenotypes, including elevated cytosolic Fe Show less

BackgroundAmyloid accumulation and degeneration of the cholinergic white matter pathways are key factors in early Alzheimer's disease pathogenesis and progression. However, the relationship between them remains unclear.ObjectiveTo investigate the association between amyloid accumulation, the integrity of cholinergic white matter pathways, and cognitive performance.MethodsThis cross-sectional study recruited 109 individuals, including 37 controls with normal cognition and 72 patients with early Alzheimer's disease. All participants underwent neuropsychological testing: the Mini-Mental Status Examination (MMSE), Clinical Dementia Rating scale with sum of box (CDR-SB), and verbal fluency tests. Cholinergic white matter integrity and amyloid burden were assessed through diffusion tensor imaging study (DTI) and amyloid positron emission tomography (PET). Stepwise linear regression analyses were performed. Partial correlations between amyloid burden and cholinergic integrity were also evaluated according to apolipoprotein E4 ( Show less

Cognitive decline is a common aspect of aging, and identifying modifiable lifestyle factors, such as physical activity and sleep, is crucial for promoting healthy brain aging. While both are individually linked to cognition, few studies have simultaneously assessed their independent and combined effects using objective wearable-based data, particularly in older Asian populations. This study aimed to examine the independent and interactive effects of wearable-assessed sleep and physical activity parameters on memory performance in healthy older adults. We also explored whether age and hippocampal volume moderated these associations. This prospective cross-sectional analysis included 88 cognitively healthy community-dwelling adults (≥60 years of age) from the Integrating Systematic Data of Geriatric Medicine to Explore the Solution for Healthy Aging cohort in Taiwan. Participants underwent 12-day wrist-worn actigraphy, brain magnetic resonance imaging, and neuropsychological assessments. Light-intensity physical activity (LPA) and wake after sleep onset (WASO) were selected based on age-adjusted partial correlations with Consortium to Establish a Registry for Alzheimer's Disease Neuropsychological Battery memory scores. Multivariate regressions, age-stratified models (cutoff=72 years), and PROCESS moderation and mediation analyses were conducted, adjusting for age, education, daytime sleepiness, and hippocampal volume. Partial correlation analyses adjusting for age showed that higher LPA (r=0.260; P=.02) and lower WASO (r=-0.251; P=.02) were significantly associated with better memory scores. Age significantly moderated both effects: LPA was beneficial beyond 73.8 years of age, and WASO was detrimental beyond 71.1 years of age. Multivariate regression models confirmed that both WASO (β=-.044; P=.04) and LPA (β=.042; P=.01) were significant predictors of memory. In subgroup analyses (age ≥72 years), both LPA (β=.054; P=.04) and WASO (β=-.111; P=.01) remained significant predictors. Moderated mediation analyses showed that WASO was associated with reduced LPA (β=-.325; P=.03), but the indirect effect on memory via LPA was not significant. Instead, WASO exerted a direct and age-moderated effect on memory performance. Hippocampal volume moderated both associations, supporting the brain reserve hypothesis. Our findings highlight WASO and LPA, as measured by wearable devices, as modifiable behavioral factors linked to memory function in older adults. The impact of these factors intensifies with advancing age and may be influenced by hippocampal reserve. Promoting daily light physical activity and maintaining sleep continuity may serve as accessible, age-tailored strategies for preserving cognitive health in aging populations. ClinicalTrials.gov NCT04207502; https://classic.clinicaltrials.gov/ct2/show/NCT04207502. Show less

Obesity is a major public health crisis associated with high mortality rates. Previous genome-wide association studies (GWAS) investigating body mass index (BMI) have largely relied on imputed data from European individuals. This study leveraged whole-genome sequencing (WGS) data from 88,873 participants from the Trans-Omics for Precision Medicine (TOPMed) Program, of which 51% were of non-European population groups. We discovered 18 BMI-associated signals (P < 5 × 10 Show less

Elevated levels of the branched chain α-amino acids valine, leucine, and isoleucine are associated with heart disease and metabolic disorders. The kinase BDK, also known as branched-chain ketoacid dehydrogenase kinase (BCKDK), is a negative regulator of branched-chain α-amino acid metabolism through deactivation of BCKDC, the branched-chain α-ketoacid dehydrogenase complex. Inhibitors of BDK increase the activity of BCKDC and could be useful therapeutic leads for cardiometabolic diseases. We describe a novel bicyclic carboxy amide as an inhibitor of BDK with in vivo activity. Show less

Biomarkers of early pathogenesis of type 1 diabetes (T1D) are crucial to enable effective prevention measures in at-risk populations before significant damage occurs to their insulin producing beta-cell mass. We recently introduced the concept of integrated parallel multi-omics and employed a novel data augmentation approach which identified promising candidate biomarkers from a small cohort of high-risk T1D subjects. We now validate selected biomarkers to generate a potential composite signature of T1D risk. Twelve candidate biomarkers, which were identified in the augmented data and selected based on their fold-change relative to healthy controls and cross-reference to proteomics data previously obtained in the expansive TEDDY and DAISY cohorts, were measured in the original samples by ELISA. All 12 biomarkers had established connections with lipid/lipoprotein metabolism, immune function, inflammation, and diabetes, but only 7 were found to be markedly changed in the high-risk subjects compared to the healthy controls: ApoC1 and PON1 were reduced while CETP, CD36, FGFR1, IGHM, PCSK9, SOD1, and VCAM1 were elevated. Results further highlight the promise of our data augmentation approach in unmasking important patterns and pathologically significant features in parallel multi-omics datasets obtained from small sample cohorts to facilitate the identification of promising candidate T1D biomarkers for downstream validation. They also support the potential utility of a composite biomarker signature of T1D risk characterized by the changes in the above markers. Show less

In response to injury, vascular smooth muscle cells (VSMCs) of the arterial wall dedifferentiate into a proliferative and migratory phenotype, leading to intimal hyperplasia. The ERK1/2 pathway participates in cellular proliferation and migration, while dual-specificity phosphatase 6 (DUSP6, also named MKP3) can dephosphorylate activated ERK1/2. We showed that DUSP6 was expressed in low baseline levels in normal arteries; however, arterial injury significantly increased DUSP6 levels in the vessel wall. Compared with wild-type mice, Show less

Transient global cerebral ischemia (tGCI) resulting from cardiac arrest causes selective neurodegeneration in hippocampal CA1 neurons. Although the effect is clear, the underlying mechanisms directing this process remain unclear. Previous studies have shown that phosphorylation of Erk1/2 promotes cell survival in response to tGCI. DUSP6 (also named MKP3) serves as a cytosolic phosphatase that dephosphorylates Erk1/2, but the role of DUSP6 in tGCI has not been characterized. We found that DUSP6 was specifically induced in the cytoplasm of hippocampal CA1 neurons 4 to 24 h after tGCI. DUSP6-deficient mice showed normal spatial memory acquisition and retention in the Barnes maze. Impairment of spatial memory acquisition and retention after tGCI was attenuated in DUSP6-deficient mice. Neurodegeneration after tGCI, revealed by Fluoro-Jade C and H&E staining, was reduced in the hippocampus of DUSP6-deficient mice and DUSP6 deficiency enhanced the phosphorylation and nuclear translocation of Erk1/2 in the hippocampal CA1 region. These data support the role of DUSP6 as a negative regulator of Erk1/2 signaling and indicate the potential of DUSP6 inhibition as a novel therapeutic strategy to treat neurodegeneration after tGCI. Show less

Dual-specificity phosphatases (DUSPs) can dephosphorylate both tyrosine and serine/threonine residues of their substrates and regulate T cell-mediated immunity and autoimmunity. The aim of this study was to investigate the potential roles of DUSPs in ankylosing spondylitis (AS). Sixty AS patients and 45 healthy controls were enrolled in this study. Associations of gene expression of 23 DUSPs in peripheral T cells with inflammatory cytokine gene expression and disease activity of AS were analyzed. Finally, we investigated whether the characteristics of AS are developed in DUSP-knockout mice. The mRNA levels of DUSP4, DUSP5, DUSP6, DUSP7, and DUSP14 in peripheral T cells were significantly higher in AS group than those of healthy controls (all p < 0.05), while DUSP22 (also named JKAP) mRNA levels were significantly lower in AS group than healthy controls (p < 0.001). The mRNA levels of DUSP4, DUSP5, DUSP6, DUSP7, and DUSP14 in T cells were positively correlated with mRNA levels of tumor necrosis factor-α (TNF-α), whereas DUSP22 was inversely correlated (all p < 0.05). In addition, inverse correlations of DUSP22 gene expression in peripheral T cells with C-reactive protein, erythrocyte sedimentation rate, and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) were observed (all p < 0.05). More importantly, aged DUSP22 knockout mice spontaneously developed syndesmophyte formation, which was accompanied by an increase of TNF-α DUSP22 may play a crucial role in the pathogenesis and regulation of disease activity of AS. Show less

Obesity is a major public health crisis associated with high mortality rates. Previous genome-wide association studies (GWAS) investigating body mass index (BMI) have largely relied on imputed data from European individuals. This study leveraged whole-genome sequencing (WGS) data from 88,873 participants from the Trans-Omics for Precision Medicine (TOPMed) Program, of which 51% were of non-European population groups. We discovered 18 BMI-associated signals ( Show less

Müller cells play a critical role in the closure of macular holes, and their proliferation and migration are facilitated by the internal limiting membrane (ILM). Despite the importance of this process, the underlying molecular mechanism remains underexplored. This study investigated the effects of ILM components on the microRNA (miRNA) profile of Müller cells. Rat Müller cells (rMC-1) were cultured with a culture insert and varying concentrations of ILM component coatings, namely, collagen IV, laminin, and fibronectin, and cell migration was assessed by measuring cell-free areas in successive photographs following insert removal. MiRNAs were then extracted from these cells and analyzed. Mimics and inhibitors of miRNA candidates were transfected into Müller cells, and a cell migration assay and additional cell viability assays were performed. The results revealed that the ILM components promoted Müller cell migration ( Show less

Single-cell RNA sequencing (scRNA-seq) approach can broadly and specifically evaluate the individual cells with minimum detection bias. To explore the individual compositional and transcriptional alteration of intestinal leukocytes in the Dual Specificity Phosphatase six knockout (D6KO) mice, we performed a scRNA-seq followed by the cell type annotation based on ImmGen database. Composition assessments found that D6KO-derived intestinal leukocytes tend to stay inactivate or immature status. The enrichment analysis showed that D6KO-derived intestinal leukocytes are less sensitive to microbes. The Show less

Glycosaminoglycans are ubiquitously expressed polysaccharides that are attached to proteoglycans. Here, we showed that ablation of the heparan sulfate (HS) polymerase Ext1 in retinal progenitor cells did not affect initial progression of retinal angiogenesis, but it disrupted the pruning of blood vessels and establishment of arterioles and venules. In the absence of retinal HS, blood vessels were also vulnerable to high oxygen tension in early postnatal stages, which could be rescued by exogenous vascular endothelial growth factor (VEGF), consistent with the role of retinal HS in the fine-tuning of VEGF signaling. Furthermore, we observed that the retinal inner limiting membrane (ILM) was disrupted by deletion of Ext1 in a timing-specific manner, suggesting that retinal HS is required for the assembly but not the maintenance of the basement membrane. Lastly, we showed that further deletion of C4st1, a chondroitin sulfate (CS) sulfation enzyme, did not affect the assembly of the ILM but, when combined with Ext1 deletion, it aggravated the retinal permeability by disrupting the retinal glycocalyx. These results demonstrate an important role of CS and HS in establishing the barrier function of the extracellular matrix. Show less

In East Asia, the breast cancer incidence rate among women aged <50 years has rapidly increased. Emerging tumors are distinctly characterized by a high prevalence of estrogen receptor (ER)-positive/human epidermal growth factor receptor (HER2)-negative cancer. In the present study, we identified unique genetic alterations in these emerging tumors. We analyzed gene copy number variations (CNVs) in breast tumors from 120 Taiwanese patients, and obtained public datasets of CNV and gene expression (GE). The data regarding CNV and GE were separately compared between East Asian and Western patients, and the overlapping genes identified in the comparisons were explored to identify the gene-gene interaction networks. In the age <50 years/ER + /HER2- subgroup, tumors of East Asian patients exhibited a higher frequency of copy number loss in APOA1/C3/A4/A5, a lipid-metabolizing gene cluster (33 vs. 10%, P < .001) and lower APOA1/C3/A4/A5 expressions than tumors of Western patients. These copy number loss related- and GE-related results were validated in another Taiwanese cohort and in two GE datasets, respectively. The copy number loss was significantly associated with poor survival among Western patients, but not among East Asian patients. Lower APOA1, APOC3, and APOA5 expressions were associated with higher ESTIMATE immune scores, indicating an abundance of tumor-infiltrating immune cells. In conclusion, APOA1/C3/A4/A5 copy number loss was more prevalent in luminal breast tumors among East Asian women aged <50 years, and its immunomodulatory effect on the tumor microenvironment possibly plays various roles in the tumor biology of East Asian patients. Show less

Strengthening the gut epithelial barrier is a potential strategy for management of gut microbiota-associated illnesses. Here, we demonstrate that dual-specificity phosphatase 6 (Dusp6) knockout enhances baseline colon barrier integrity and ameliorates dextran sulfate sodium (DSS)-induced colonic injury. DUSP6 mutation in Caco-2 cells enhances the epithelial feature and increases mitochondrial oxygen consumption, accompanied by altered glucose metabolism and decreased glycolysis. We find that Dusp6-knockout mice are more resistant to DSS-induced dysbiosis, and the cohousing and fecal microbiota transplantation experiments show that the gut/fecal microbiota derived from Dusp6-knockout mice also confers protection against colitis. Further culturomics and mono-colonialization experiments show that one gut microbiota member in the genus Duncaniella confers host protection from DSS-induced injury. We identify Dusp6 deficiency as beneficial for shaping the gut microbiota eubiosis necessary to protect against gut barrier-related diseases. Show less

Phosphatidylinositol 3-kinase catalytic subunit type 3 (PIK3C3), the mammalian ortholog of yeast vesicular protein sorting 34 (Vps34), belongs to the phosphoinositide 3-kinase (PI3K) family. PIK3C3 can phosphorylate phosphatidylinositol (PtdIns) to generate phosphatidylinositol 3-phosphate (PI3P), a phospholipid central to autophagy. Inhibition of PIK3C3 successfully inhibits autophagy. Autophagy maintains cell survival when modifications occur in the cellular environment and helps tumor cells resist metabolic stress and cancer treatment. In addition, PIK3C3 could induce oncogenic transformation and enhance tumor cell proliferation, growth, and invasion through mechanisms independent of autophagy. This review addresses the structural and functional features, tissue distribution, and expression pattern of PIK3C3 in a variety of human tumors and highlights the underlying mechanisms involved in carcinogenesis. The implications in cancer biology, patient prognosis prediction, and cancer therapy are discussed. Altogether, the discovery of pharmacological inhibitors of PIK3C3 could reveal novel strategies for improving treatment outcomes for PIK3C3-mediated human diseases. Show less

Mitochondrial dysfunction is involved in the pathogenesis of atherosclerosis, the primary risk factor for ischemic stroke. This study aims to explore the role of mitochondrial genomic variations in ischemic stroke, and to uncover the nuclear genes involved in this relationship. Eight hundred and thirty Taiwanese patients with a history of ischemic stroke and 966 normal controls were genotyped for their mitochondrial haplogroup (Mthapg). Cytoplasmic hybrid cells (cybrids) harboring different Mthapgs were used to observe functional differences under hypoxia-ischemia. RNA sequencing (RNASeq) was conducted to identify the particularly elevated mRNA. The patient study identified an association between Mthapg F1 and risk of ischemic stroke (OR 1.72:1.27-2.34, Show less

Benign prostatic hyperplasia (BPH) is the most common urologic disease affecting aging men. The pathogenesis of BPH is multi-factorial, and chronic inflammation (CI) might be the central mechanism. Interleukin (IL)-27 signaling has been suggested as a modulator in autoimmune and inflammatory conditions. In this study, we used microarray experiments to analyze gene expression and molecular phenotypic associated with BPH progression, with a particular focus on CI and IL-27/IL-27RA signaling, and verified the microarray data in cell biology experiments. Thirty BPH patients' specimens and clinical parameters were analyzed. BPH patients were divided into two groups based on the average prostate volume (41.5 mL): group 1, ≤40 mL; and group 2, >40 mL. Microarray experiments were conducted to identify differentially expressed genes (DEGs) by applying appropriate biostatistics to normalize and analyze the dataset. The candidate gene ( Eighty-three percent of BPH specimens contained inflammatory infiltrates, and the predominant type was CI. The serum PSA levels and prevalence of CI were higher in group 2. Microarray experiments identified 361 DEGs between these 2 groups. Our study revealed that down-regulation of Show less

Recently, the spectrum of background mutation in the genes implicated in sudden arrhythmic death syndrome (SADS), has been elucidated in the Caucasian populations. However, this information is largely unknown in the Asian populations. We assessed the background rare variants (minor allele frequency < 0.01) of major SADS genes in whole genome sequence data of 1514 healthy Taiwanese subjects from the Taiwan Biobank. We found up to 45% of healthy subjects have a rare variant in at least one of the major SADS genes. Around 3.44% of healthy subjects had multiple mutations in one or multiple genes. The background mutation rates in long QT syndrome, catecholaminergic polymorphic ventricular tachycardia, and arrhythmogenic right ventricular cardiomyopathy genes were similar, but those in Brugada syndrome (BrS) (SCN5A) and hypertrophic cardiomyopathy (HCM) genes (MYBPC3, MYH7, and TNNT2) were higher, compared to those reported in the Caucasian populations. Furthermore, the rate of incidental pathogenic variant was highest in MYBPC3 gene. Finally, the number of variant was proportional to the exon length of the gene (R2 = 0.486, P = 0.0056) but not related to its functional or evolutionary importance (degree of evolutionary conservation) (R2 = 0.0008, P = 0.9218), suggesting that the mutation was random. The ratio of variant number over exon nucleotide length was highest in MYBPC3, MYH7, and TNNT2 genes. Unique features of background SADS gene mutation in the Asian populations include higher prevalence of incidental variant in HCM, BrS, and long QT 3 (SCN5A) genes. HCM genes have the highest variant number per exon length. Show less

Glioblastoma (GBM) is the most aggressive type of brain tumor, with strong invasiveness and a high tolerance to chemotherapy. Despite the current standard treatment combining temozolomide (TMZ) and radiotherapy, glioblastoma can be incurable due to drug resistance. The existence of glioma stem-like cells (GSCs) is considered the major reason for drug resistance. However, the mechanism of GSC enrichment remains unclear. Herein, we found that the expression and secretion of angiopoietin-like 4 protein (ANGPTL4) were clearly increased in GSCs. The overexpression of ANGPTL4 induced GSC enrichment that was characterized by polycomb complex protein BMI-1 and SRY (sex determining region Y)-box 2 (SOX2) expression, resulting in TMZ resistance in GBM. Furthermore, epidermal growth factor receptor (EGFR) phosphorylation induced 4E-BP1 phosphorylation that was required for ANGPTL4-induced GSC enrichment. In particular, ANGPTL4 induced 4E-BP1 phosphorylation by activating phosphoinositide 3-kinase (PI3K)/AKT and extracellular signal-regulated kinase (ERK) cascades for inducing stemness. To elucidate the mechanism contributing to ANGPTL4 upregulation in GSCs, chromatin immunoprecipitation coupled with sequencing (ChIP-Seq) revealed that specificity protein 4 (Sp4) was associated with the promoter region, -979 to -606, and the luciferase reporter assay revealed that Sp4 positively regulated activity of the ANGPTL4 promoter. Moreover, both ANGPTL4 and Sp4 were highly expressed in GBM and resulted in a poor prognosis. Taken together, Sp4-mediated ANGPTL4 upregulation induces GSC enrichment through the EGFR/AKT/4E-BP1 cascade. Show less

Recent studies implicate a strong association between elevated plasma branched-chain amino acids (BCAAs) and insulin resistance (IR). However, a causal relationship and whether interrupted BCAA homeostasis can serve as a therapeutic target for diabetes remain to be established experimentally. In this study, unbiased integrative pathway analyses identified a unique genetic link between obesity-associated IR and BCAA catabolic gene expression at the pathway level in human and mouse populations. In genetically obese ( Show less

Mitogen-activated protein kinases (MAPKs) are key regulators of signal transduction and cell responses. Abnormalities in MAPKs are associated with multiple diseases. Dual-specificity phosphatases (DUSPs) dephosphorylate many key signaling molecules, including MAPKs, leading to the regulation of duration, magnitude, or spatiotemporal profiles of MAPK activities. Hence, DUSPs need to be properly controlled. Protein post-translational modifications, such as ubiquitination, phosphorylation, methylation, and acetylation, play important roles in the regulation of protein stability and activity. Ubiquitination is critical for controlling protein degradation, activation, and interaction. For DUSPs, ubiquitination induces degradation of eight DUSPs, namely, DUSP1, DUSP4, DUSP5, DUSP6, DUSP7, DUSP8, DUSP9, and DUSP16. In addition, protein stability of DUSP2 and DUSP10 is enhanced by phosphorylation. Methylation-induced ubiquitination of DUSP14 stimulates its phosphatase activity. In this review, we summarize the knowledge of the regulation of DUSP stability and ubiquitination through post-translational modifications. Show less

Angiopoietin-like 4 (ANGPTL4) is an endogenous inhibitor of lipoprotein lipase that modulates lipid levels, coronary atherosclerosis risk, and nutrient partitioning. We hypothesize that loss of ANGPTL4 function might improve glucose homeostasis and decrease risk of type 2 diabetes (T2D). We investigate protein-altering variants in ANGPTL4 among 58,124 participants in the DiscovEHR human genetics study, with follow-up studies in 82,766 T2D cases and 498,761 controls. Carriers of p.E40K, a variant that abolishes ANGPTL4 ability to inhibit lipoprotein lipase, have lower odds of T2D (odds ratio 0.89, 95% confidence interval 0.85-0.92, p = 6.3 × 10 Show less

Urothelial carcinoma (UC) carcinogenesis has been hypothesized to occur through epigenetic repression of tumor-suppressor genes (TSGs). By quantitative real-time polymerase chain reaction array, we found that one potential TSG, angiopoietin-like 4 (ANGPTL4), was expressed at very low levels in all bladder cancer cell lines we examined. Previous studies had demonstrated that ANGPTL4 is highly expressed in some cancers, but downregulated, by DNA methylation, in others. Consequently, owing to these seemingly conflicting functions in distinct cancers, the precise role of ANGPTL4 in the etiology of UC remains unclear. In this study, using methylation-specific PCR and bisulfite pyrosequencing, we show that ANGPTL4 is transcriptionally repressed by DNA methylation in UC cell lines and primary tumor samples, as compared with adjacent noncancerous bladder epithelium. Functional studies further demonstrated that ectopic expression of ANGPTL4 potently suppressed UC cell proliferation, monolayer colony formation in vitro, and invasion, migration, and xenograft formation in vivo. Surprisingly, circulating ANGPTL4 was significantly higher in plasma samples from UC patients than normal control, suggesting it might be secreted from other cell types. Interestingly, our data also indicated that exogenous cANGPTL4 could promote cell proliferation and cell migration via activation of signaling through the Erk/focal adhesion kinase axis. We further confirmed that mouse xenograft tumor growth could be promoted by administration of exogenous cANGPTL4. Finally, immunohistochemistry demonstrated that ANGPTL4 was downregulated in tumor cells but overexpressed in tumor adjacent stromal tissues of muscle-invasive UC tissue samples. In conclusion, our data support dual roles for ANGPTL4 in UC progression, either as a tumor suppressor or oncogene, in response to microenvironmental context. Show less

Branched-chain amino acids (BCAA) are strongly associated with dysregulated glucose and lipid metabolism, but the underlying mechanisms are poorly understood. We report that inhibition of the kinase (BDK) or overexpression of the phosphatase (PPM1K) that regulates branched-chain ketoacid dehydrogenase (BCKDH), the committed step of BCAA catabolism, lowers circulating BCAA, reduces hepatic steatosis, and improves glucose tolerance in the absence of weight loss in Zucker fatty rats. Phosphoproteomics analysis identified ATP-citrate lyase (ACL) as an alternate substrate of BDK and PPM1K. Hepatic overexpression of BDK increased ACL phosphorylation and activated de novo lipogenesis. BDK and PPM1K transcript levels were increased and repressed, respectively, in response to fructose feeding or expression of the ChREBP-β transcription factor. These studies identify BDK and PPM1K as a ChREBP-regulated node that integrates BCAA and lipid metabolism. Moreover, manipulation of the BDK:PPM1K ratio relieves key metabolic disease phenotypes in a genetic model of severe obesity. Show less

Mitochondrial pyruvate dehydrogenase kinases 1-4 (PDKs1-4) negatively regulate activity of the pyruvate dehydrogenase complex (PDC) by reversible phosphorylation. PDKs play a pivotal role in maintaining energy homeostasis and contribute to metabolic flexibility by attenuating PDC activity in various mammalian tissues. Cumulative evidence has shown that the up-regulation of PDK4 expression is tightly associated with obesity and diabetes. In this investigation, we test the central hypothesis that PDKs1-4 are a pharmacological target for lowering glucose levels and restoring insulin sensitivity in obesity and type 2 diabetes (T2D). Diet-induced obese (DIO) mice were treated with a liver-specific pan-PDK inhibitor 2-[(2,4-dihydroxyphenyl) sulfonyl]isoindoline-4,6-diol (PS10) for four weeks, and results compared with PDK2/PDK4 double knockout (DKO) mice on the same high fat diet (HFD). Both PS10-treated DIO mice and HFD-fed DKO mice showed significantly improved glucose, insulin and pyruvate tolerance, compared to DIO controls, with lower plasma insulin levels and increased insulin signaling in liver. In response to lower glucose levels, phosphorylated AMPK in PS10-treated DIO and HFD-fed DKO mice is upregulated, accompanied by decreased nuclear carbohydrate-responsive element binding protein (ChREBP). The reduced ChREBP signaling correlates with down-regulation of hepatic lipogenic enzymes (ACC1, FAS, and SCD1), leading to markedly diminished hepatic steatosis in both study groups, with lower circulating cholesterol and triacylglyceride levels as well as reduced fat mass. PS10-treated DIO as well as DKO mice showed predominant fatty acid over glucose oxidation. However, unlike systemic DKO mice, increased hepatic PDC activity alone in PS10-treated DIO mice does not raise the plasma total ketone body level. Our findings establish that specific targeting of hepatic PDKs with the PDK inhibitor PS10 is an effective therapeutic approach to maintaining glucose and lipid homeostasis in obesity and T2D, without the harmful ketoacidosis associated with systemic inhibition of PDKs. Show less

Atherosclerosis is a process of imbalanced lipid metabolism in the vascular walls. The underlying pathology mainly involves the deposition of oxidized lipids in the endothelium and the accumulation of cholesterol in macrophages. Macrophages export excessive cholesterol (cholesterol efflux) through ATP-binding cassette transporter A1 (ABCA1) to counter the progression of atherosclerosis. We synthesized novel chalcone derivatives and assessed their effects and the underlying mechanisms on ABCA1 expression in macrophages. Human THP-1 macrophages were treated with synthetic chalcone derivatives for 24 h. In Western blot and flow cytometry analyses, a chalcone derivative, ( Show less