👤 Dipanjana Ghosh

Congenital myasthenic syndrome is a group of rare genetic disorders affecting transmission across the neuromuscular junction. Patients present with variable ocular, bulbar, respiratory, and extremity weakness that may respond to symptomatic therapies. We identified 18 patients with congenital myasthenic syndrome from a pediatric neuromuscular center over a decade. Through a retrospective chart review, we characterize demographic profile, clinical features, genetic variants, treatment, and follow-up of these patients. Patients had the following genetic subtypes: Increasing recognition of this rare syndrome will lead to early diagnosis and prompt treatment. Prompt utilization of genetic testing will identify novel variants and the expanding phenotype of this condition. Show less

Angiopoietin-like protein (ANGPTL) family members, mainly ANGPTL3, ANGPTL4 and ANGPTL8, are physiological inhibitors of lipoprotein lipase (LPL), and play a critical role in lipoprotein and triglyceride metabolism in response to nutritional cues. ANGPTL8 has been described by different names in various studies and has been ascribed various functions at the systemic and cellular levels. Circulating ANGPTL8 originates mainly from the liver and to a smaller extent from adipose tissues. In the blood, ANGPTL8 forms a complex with ANGPTL3 or ANGPTL4 to inhibit LPL in fed or fasted conditions, respectively. Evidence is emerging for additional intracellular and receptor-mediated functions of ANGPTL8, with implications in NFκB mediated inflammation, autophagy, adipogenesis, intra-cellular lipolysis and regulation of circadian clock. Elevated levels of plasma ANGPTL8 are associated with metabolic syndrome, type 2 diabetes, atherosclerosis, hypertension and NAFLD/NASH, even though the precise relationship is not known. Whether ANGPTL8 has direct pathogenic role in these diseases, remains to be explored. In this review, we develop a balanced view on the proposed association of this protein in the regulation of several pathophysiological processes. We also discuss the well-established functions of ANGPTL8 in lipoprotein metabolism in conjunction with the emerging novel extracellular and intracellular roles of ANGPTL8 and the implicated metabolic and signalling pathways. Understanding the diverse functions of ANGPTL8 in various tissues and metabolic states should unveil new opportunities of therapeutic intervention for cardiometabolic disorders. Show less

Gene environment interactions leading to epigenetic alterations play pivotal role in the pathogenesis of Coronary Artery Disease (CAD). Altered DNA methylation is one such epigenetic factor that could lead to altered disease etiology. In this study, we comprehensively identified methylation sites in several genes that have been previously associated with young CAD patients. The study population consisted of 42 healthy controls and 33 young CAD patients (age group <50 years). We performed targeted bisulfite sequencing of promoter as well as gene body regions of several genes in various pathways like cholesterol synthesis and metabolism, endothelial dysfunction, apoptosis, which are implicated in the development of CAD. We observed that the genes like GALNT2, HMGCR were hypermethylated in the promoter whereas LDLR gene promoter was hypomethylated indicating that intracellular LDL uptake was higher in CAD patients. Although APOA1 did not show significant change in methylation but APOC3 and APOA5 showed variation in methylation in promoter and exonic regions. Glucokinase (GCK) and endothelial nitric oxide synthase 3 (NOS3) were hyper methylated in the promoter. Genes involved in apoptosis (BAX/BCL2/AKT2) and inflammation (PHACTR1/LCK) also showed differential methylation between controls and CAD patients. A combined analysis of the methylated CpG sites using machine learning tool revealed 14 CpGs in 11 genes that could discriminate CAD cases from controls with over 93% accuracy. This study is unique because it highlights important gene methylation alterations which might predict the risk of young CAD in Indian population. Large scale studies in different populations would be important for validating our findings and understanding the epigenetic events associated with CAD. Show less

We examined the role of hepatocyte micro-RNA-122 and hypothalamic neuropeptides, in weanling (21d) female rats exposed to calorie restriction induced growth restriction either prenatally (IUGR), postnatally (PNGR) or both (IPGR) vs. ad lib fed controls (CON). IUGR were hyperinsulinemic, hyperleptinemic and dyslipidemic with high circulating miR-122. In contrast, PNGR and IPGR displayed insufficient glucose, insulin and leptin amidst high ketones with a dichotomy in circulating miR-122 of PNGRShow less

Dysregulated hepatic de novo lipogenesis contributes to the pathogenesis of nonalcoholic fatty liver disease in both humans and rodents. Clinical evidence suggests fatty liver to have a positive correlation with serum lead (Pb Show less

Adipose tissue dysfunction is associated with inflammation, metabolic syndrome and other diseases in aging. Recent work has demonstrated that compromised autophagy activity in aging adipose tissue promotes ER stress responses, contributing to adipose tissue and systemic inflammation in aging. Phosphatidylinositol 3-kinase catalytic subunit type 3 (Pik3c3) is an 887 amino acid lipid kinase that regulates intracellular membrane trafficking and autophagy activity. To address the mechanistic link between autophagy and ER stress response in aging adipose tissue, we generated a line of adipose tissue-specific Show less

To identify loci associated with abdominal fat and replicate prior findings, we performed genome-wide association (GWA) studies of abdominal fat traits: subcutaneous adipose tissue (SAT); visceral adipose tissue (VAT); total adipose tissue (TAT) and visceral to subcutaneous adipose tissue ratio (VSR). Sex-combined and sex-stratified analyses were performed on each trait with (TRAIT-BMI) or without (TRAIT) adjustment for body mass index (BMI), and cohort-specific results were combined via a fixed effects meta-analysis. A total of 2513 subjects of European descent were available for the discovery phase. For replication, 2171 European Americans and 772 African Americans were available. A total of 52 single-nucleotide polymorphisms (SNPs) encompassing 7 loci showed suggestive evidence of association (P<1.0 × 10(-6)) with abdominal fat in the sex-combined analyses. The strongest evidence was found on chromosome 7p14.3 between a SNP near BBS9 gene and VAT (rs12374818; P=1.10 × 10(-7)), an association that was replicated (P=0.02). For the BMI-adjusted trait, the strongest evidence of association was found between a SNP near CYCSP30 and VAT-BMI (rs10506943; P=2.42 × 10(-7)). Our sex-specific analyses identified one genome-wide significant (P<5.0 × 10(-8)) locus for SAT in women with 11 SNPs encompassing the MLLT10, DNAJC1 and EBLN1 genes on chromosome 10p12.31 (P=3.97 × 10(-8) to 1.13 × 10(-8)). The THNSL2 gene previously associated with VAT in women was also replicated (P=0.006). The six gene/loci showing the strongest evidence of association with VAT or VAT-BMI were interrogated for their functional links with obesity and inflammation using the Biograph knowledge-mining software. Genes showing the closest functional links with obesity and inflammation were ADCY8 and KCNK9, respectively. Our results provide evidence for new loci influencing abdominal visceral (BBS9, ADCY8, KCNK9) and subcutaneous (MLLT10/DNAJC1/EBLN1) fat, and confirmed a locus (THNSL2) previously reported to be associated with abdominal fat in women. Show less

Controversy exists on the benefits versus harms of n-6 polyunsaturated fatty acids (n-6 PUFA). Although n-6 PUFA demonstrates anti-atherosclerotic properties, survival following cardiac remodeling may be compromised. We hypothesized that n-6 PUFA like linoleic acid (LA) or other downstream PUFAs like γ-linolenic acid or arachidonic acid alter the transforming growth factor-β (TGFβ)-collagen axis in the heart. Excess dietary LA increased the collagen I/III ratio in the mouse myocardium, leading to cardiac "stiffening" characterized by impaired transmitral flow indicative of early diastolic dysfunction within 5 weeks. In vitro, LA under TGFβ1 stimulation increased collagen I and lysyl oxidase (LOX), the enzyme that cross-links soluble collagen resulting in deposited collagen. Overexpression of fatty acid desaturase 2 (fads2), which metabolizes LA to downstream PUFAs, reduced collagen deposits, LOX maturation, and activity with LA, whereas overexpressing fads1, unrelated to LA desaturation, did not. Furthermore, fads2 knockdown by RNAi elevated LOX activity and collagen deposits in fibroblasts with LA but not oleic acid, implying a buildup of LA for aggravating such pro-fibrotic effects. As direct incubation with γ-linolenic acid or arachidonic acid also attenuated collagen deposits and LOX activity, we concluded that LA itself, independent of other downstream PUFAs, promotes the pro-fibrotic effects of n-6 PUFA. Overall, these results attempt to reconcile opposing views of n-6 PUFA on the cardiovascular system and present evidence supporting a cardiac muscle-specific effect of n-6 PUFAs. Therefore, aggravation of the collagen I/III ratio and cardiac stiffening by excess n-6 PUFA represent a novel pathway of cardiac lipotoxicity caused by high n-6 PUFA diets. Show less

α-Eleostearic acid and punicic acid, two typical conjugated linolenic acid (CLnA) isomers present in bitter gourd and snake gourd oil respectively, exhibit contrasting cis-trans configuration which made them biologically important. Rats were divided into six groups. Group 1 was control and group 2 was treated control. Rats in the groups 3 and 4 were treated with mixture of α-eleostearic acid and punicic acid (1:1) (0.5% and 1.0% respectively) while rats in the groups 5 and 6 were treated with 0.5% of α-eleostearic acid and 0.5% of punicic acid respectively along with sodium arsenite by oral gavage once per day. Results showed that increase in nitric oxide synthase (NOS) activity, inflammatory markers expression, platelet aggregation, lipid peroxidation, protein oxidation, DNA damage and altered expression of liver X receptor-α (LXR-α) after arsenite treatment were restored with the supplementation of oils containing CLnA isomers. Altered activities of different antioxidant enzymes such as superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and ferric reducing ability of plasma (FRAP) also restored after oil supplementation. Altered morphology and fluidity of erythrocyte membrane studied by atomic force and scanning electron microscopy, after stress induction were significantly improved due to amelioration in cholesterol/phospholipid ratio and fatty acid profile of membrane. Oils treatment also improved morphology of liver and fatty acid composition of hepatic lipid. Overall two isomers showed synergistic antioxidant and anti-inflammatory effect against induced perturbations and membrane disintegrity. Synergistic antioxidant and anti-inflammatory role of these CLnA isomers were established by this study. Show less

The tumor suppressor, PTEN is key to the regulation of diverse cellular processes, making it a prime candidate to be tightly regulated. The PTEN level is controlled in a major way by E3 ligase-mediated degradation through the Ubiquitin-Proteasome System (UPS). Nedd 4-1, XIAP, and WWP2 have been shown to maintain PTEN turnover. Here, we report that CHIP, the chaperone-associated E3 ligase, induces ubiquitination and regulates the proteasomal turnover of PTEN. It was apparent from our findings that PTEN transiently associates with the molecular chaperones and thereby gets diverted to the degradation pathway through its interaction with CHIP. The TPR domain of CHIP and parts of the N-terminal domain of PTEN are required for their interaction. Overexpression of CHIP leads to elevated ubiquitination and a shortened half-life of endogenous PTEN. On the other hand, depletion of endogenous CHIP stabilizes PTEN. CHIP is also shown to regulate PTEN-dependent transcription presumably through its down-regulation. PTEN shared an inverse correlation with CHIP in human prostate cancer patient samples, thereby triggering the prospects of a more complex mode of PTEN regulation in cancer. Show less

In the developing pancreas, the onset of exocrine differentiation is driven by the activity of the PTF1 (pancreas transcription factor 1) transcriptional complex, which is comprised of the class II bHLH (basic helix-loop-helix) protein, Ptf1-p48 [also known as Ptf1a (pancreas specific transcription factor 1a)], and a class I E-box binding partner. Activity of the PTF1 complex is normally inhibited by the Notch signalling pathway, a process mediated by Notch effector proteins in the HES (Hairy/Enhancer of Split) family of bHLH transcriptional repressors. In the present study, we show that this inhibitory effect occurs through direct interaction between HES family members and Ptf1-p48. The HES family members Hey1 (hairy/enhancer-of-split related with YRPW motif 1) and Hey2 co-immunoprecipitate with Ptf1-p48, and Ptf1-p48 binding by Hes1 is also evident in yeast two-hybrid and GST (glutathione S-transferase) pull-down assays. The ability of Hes1 to interact with Ptf1-p48 resides within a fragment comprised of the bHLH, Orange and C-terminal domains, and does not require the N-terminal or WRPW elements. The ability of truncated versions of Hes1 to bind Ptf1-p48 correlates with their ability to down-regulate the activity of the PTF1 transcriptional complex, defining Ptf1-p48 binding as the most likely mechanism by which Notch effector proteins delay exocrine pancreatic differentiation. Show less

Prostate cancer is the most common and invasive type of cancer among American men, and the second leading cause of cancer-elated deaths in the United States. Unfortunately, an effective therapeutic regimen is still lacking for advance stages of the disease. Recently, MEK5 has been shown to overexpress in prostate cancer and is associated with poor survival outcome. MEK5 exists as alpha- and beta-isoforms. MEK5alpha induces cell proliferation by activating its downstream molecules, whereas MEK5beta expression is associated with inhibition of cell growth. We have recently shown that exogenous expression of c-myc promoter-binding protein 1 (MBP-1) induces prostate cancer cell death (Ghosh, A. K., Steele, R., and Ray, R. B. (2005) Cancer Res. 65, 718-721). In this study, we have investigated whether inhibition of MEK5 signaling pathway can modulate prostate cancer cell growth. MBP-1 is a general transcriptional repressor and modulates a number of cellular genes. Therefore, we examined the endogenous expression status of MEK5 in androgen-independent prostate cancer cells upon recombinant adenovirus-mediated introduction of MBP-1. Our results demonstrated that MBP-1 expression reduced the endogenous MEK5alpha protein level; on the other hand, MEK5beta expression was enhanced significantly. Transduction of MBP-1 modulates the downstream signaling molecules of MEK5, such as activation of the cyclin D1 promoter and MEF2C transcriptional activities in androgen-independent prostate cancer cells. MBP-1 expression also modulates MEK5-mediated activation of NF-kappaB. Further analysis suggested that MBP-1 physically associates with MEK5 and induces proteasome-mediated degradation of the MEK5 protein, which appears to occur independently of ubiquitination. Together, our results suggested a novel role of MBP-1 for suppression of prostate cancer cell growth by regulating the MEK5-mediated signaling pathway. Show less