👤 K Sreekumaran Nair

Lead is a toxic heavy metal that poses significant health risks, which include neurodevelopmental disorders such as autism spectrum disorder (ASD). This review examines the effects of lead neurotoxicity on synaptic pathways which are relatively unexplored and their potential role in the development of ASD. Lead exposure occurs through various environmental sources, including contaminated water, soil, paint, and industrial appliances. Once absorbed, lead accumulates in soft tissues and bones, causes prolonged neurological damage, especially in children. ASD is characterised by impaired communication, repetitive behaviours, and cognitive challenges, with increasing evidence linking environmental factors like heavy metal exposure to its onset. Synaptic signalling disruption is a key aspect of ASD and lead interferes with the synaptic pathways by inhibiting calcium influx, leading to cognitive impairments and memory issues. This review is an overview of the previously reported findings that explains the role of lead in reducing N-methyl-D-aspartate receptors (NMDAR) function, disrupting the brain-derived neurotrophic factor (BDNF) pathway, and impairing Wnt, GABAergic and dopaminergic signalling pathways. These alterations result in cognitive decline, impaired synaptic plasticity and increased ASD symptoms. Understanding these mechanisms is crucial for developing strategies to mitigate the adverse effects of lead exposure on neurodevelopment. Show less

Heterozygous familial hypercholesterolemia (FH), a monogenic cause for premature coronary artery disease (CAD) is often underdiagnosed. In individuals who meet the FH diagnostic criteria and lack pathogenic variants, polygenic factors are recognized as potential contributors. This study aimed to characterize the spectrum of genetic variants and determine the low-density lipoprotein polygenic risk score (LDL-PRS) among clinically diagnosed FH participants from South India. We recruited 116 unrelated participants with a pretreatment LDL- C concentration ≥ 190 mg/dl and a DLCN (Dutch Lipid Clinic Network) score ≥ 3. Targeted next-generation sequencing (NGS) of 23 lipid related genes and 12-SNP (Single nucleotide polymorphism) genotyping were performed. NGS identified 39 variants including 13 pathogenic and 26 variants of unknown significance (VUS) some of which were in non-classical genes: ABCG5, ABCG8, APOE, PPP1R17, SREBF2. Pathogenic variants were detected in 66.7% of those with definite FH,19.7% in probable FH and 2.7% in possible FH. Overall,66% were variant negative. Among variant negative (FH/V-) participants, 64% demonstrated high LDL-PRS, whereas 70% of variant positive participants also exhibited elevated scores; suggesting a contributory role of polygenic factors across both groups. Additionally, the observation that variant positive individuals with high LDL-PRS have an increased risk of coronary artery disease (CAD) adds important nuance to risk stratification within genetically confirmed FH patients. Confirmation of diagnosis by genetic testing is essential for the diagnosis of FH. Although LDL-PRS may offer little benefit in variant negative cases and improve CAD risk prediction in variant positive individuals, large scale studies are essential to validate its clinical utility and assess whether inclusion of additional LDL- raising SNPs could enhance the detection of polygenic FH in the Indian population. Show less

Lipoprotein (a) [Lp (a)] may confer pro-thrombotic potential, and high concentrations may be an independent risk for MI. This systematic review sought to investigate the association of Lp (a) levels with post-revascularization Major Adverse Cardiac Events (MACE) in patients with CAD, ACS, and DM. A systematic literature search for original investigations was performed using PubMed/MEDLINE, Embase, Scopus, and Google Scholar, searching for articles (meeting inclusion criteria) focusing on the relationship between Lp(a), DM, and PCI in patients with ACS, MI, or IHD and the impact on cardiovascular outcomes. The data was abstracted and descriptively summarized. The systematic review selected four relevant articles: 3 prospective Konishi et al., (2016); Silverio et al., (2022); and Li et al., (2023) and one retrospective (Takahashi et al., 2020). Total population: 4624, total males: 3719. Konishi et al. (2016) concluded that an elevated Lp(a) is an independent risk factor for cardiac death and/or ACS recurrence in diabetics undergoing PCI. The adjusted OR for cardiac death and ACS in the high Lp(a) group vs. the low Lp(a) group was 1.20 (CI 1.00-1.42), p = 0.04. Takahashi et al. (2020) showed that after adjusting for clinical covariates, high Lp(a) was independently associated with a higher frequency of MACE and poorer long-term outcomes compared to low Lp(a). The adjusted OR for the risk of MACE in patients with high Lp (a) vs. low Lp (a) was 1.83 (CI 1.16-2.95), p = 0.009. Silverio et al. (2022) showed that while there was an increased risk of recurrent MI in this patient population without DM, it was not confirmed in patients with DM. Compared with the lowest Lp (a) category, non-DM patients with very high Lp (a) >70 mg/dl vs. low Lp (a) showed a higher risk of recurrent MI and all-cause death; adjusted OR 2.839 (CI 1.382-5.832), p = 0.005. In diabetics, high Lp (a) vs. low Lp (a) = 1.115 (CI 0.405-3.071), p = 0.833. There is some evidence that Lp (a) levels are an independent risk factor for MACE in patients who underwent PCI for CAD. There is also some evidence that elevated Lp (a) levels are associated with a worse prognosis in patients with DM after PCI, but this association is not consistent in the literature. Further prospective multicenter studies are required in order to elucidate this association. Show less

MYD88 is a signal-transducing adaptor protein that plays a central role in Toll-like receptor and interleukin 1 receptor signalling through activation of the NF-κB pathway. The somatic L265P mutation in Show less

Pancreatic alpha cells modulate beta cell function in a paracrine manner through the release of glucagon. However, the detailed molecular architecture underlying alpha-to-beta cell regulation remains poorly characterized. Here, we show that the glucagon-like peptide-1 receptor (GLP1R) is enriched as nanodomains on beta cell membranes that contact alpha cells, in keeping with increased single-molecule transcript expression. At low glucose, beta cells next to alpha cells directly sense micromolar glucagon release by pre-internalizing GLP1R. Pre-internalized GLP1R is associated with earlier beta cell Ca Show less

Adipocytokines, including leptin, adiponectin, and resistin, are key mediators linking adiposity, insulin resistance, and inflammation. We present the first genome-wide association study (GWAS; N = 5258) and exome-wide association study (ExWAS; N = 4578) on leptin, adiponectin, and resistin in South Asian population. We identified novel associations in genes ZNF467, and LEPREL2 for leptin; ZNF467, LEPREL2, CRLF3, ZNF732, SOX30, XIRP1, ATP8B3, SPATA2L, TMCO4, TLN2, ABCA12, and SHB for adiponectin; and D2HGDH for resistin. Additionally, we confirmed known associations of FTO, MC4R, and HOXB3 with leptin and ADIPOQ with adiponectin. Notably, ADIPOQ variants were consistently significant across GWAS, ExWAS, and gene-based analyses, reinforcing their central role in regulating adiponectin levels. Most of these novel associations identified were population-specific, highlighting the importance of studying diverse populations to uncover unique genetic signals. After adjusting for BMI, the associations with adiponectin and resistin remained significant, whereas most associations for leptin weakened in both effect size and significance. Functional annotation revealed that the identified variants were enriched for expression in adipose tissue, the brain (cerebellar hemisphere and cerebral cortex), and the pituitary gland. These variants act as eQTLs and splice-QTLs in adipose, brain, and pancreas, suggesting cross-tissue regulatory mechanisms. ExWAS further implicated rare variant burden in genes such as LONP1, ZNF335, and TTC16 for adiponectin and resistin. These findings enhance our understanding of adipocytokine biology, emphasises the need for population-specific genetic research, and lays foundation for future functional studies. Show less

Childhood obesity (OB) is influenced by complex gene-environmental interaction. While genetics of adult OB have been extensively studied, polygenic childhood OB in non-European populations is still underexplored. Furthermore, in a developing nation such as India, how the environmental component strongly modulated by the socioeconomic status (SES) shapes the genetic susceptibility is crucial to understand. A two-staged genome-wide association study (GWAS; N = 5673) and an independent exome-wide association study (ExWAS; N = 4963) were performed using a generalized linear model assuming additive effect to identify the common and rare genetic variants respectively associated with childhood OB. Rare-variant burden testing was also performed. We used the gene expression profiles and regulatory data from public databases to explain the novel associations. The implications of SES as a potential modifier of genetic susceptibility were evaluated. GWAS identified novel associations in TCF7L2, IMMP2L, IPMK, CDC5L, SNTG1, and MX1, whereas ExWAS uncovered CNTN4, COQ4, TNFRSF10D, FLG-AS1, and BMP3. Both GWAS and ExWAS validated known associations in FTO and MC4R. Furthermore, rare-variant testing highlighted the role of 101 genes. We also observed that SES can modulate the inherent susceptibility to OB. Our study identified genetic variants associated with childhood OB and highlighted the gene-environmental interaction in childhood OB. Show less

Elucidating the genetic basis of lipid metabolism in children is essential for early intervention in dyslipidemia and cardiovascular diseases. We performed a two-staged genome-wide association study (GWAS; N = 5412) and an independent exome-wide association study (ExWAS; N = 4750) on lipid parameters-HDL, LDL, Triglycerides (TG), Total Cholesterol (TC) in Indian school-going children - the largest single-cohort paediatric lipid study till date. GWAS identified robust associations at established loci, including CETP for HDL; CELSR2, and PSRC1 for LDL and TC, and GCKR, ZNF259, and TBL2 for TG. We also validated known associations at sub-GWAS significance in FADS2, GATAD2A, PRKCA, and QKI. Exome-based analyses further refined functional variants within these loci and revealed additional known loci in ALDH1A2 for HDL; APOE, APOC1, TM6SF2, CILP2, TOMM40, for LDL and TC; and APOA5, BUD13 for TG and novel loci in ATP8B3, MYH7B, GYS2, and RNF8 for TG. Conditional analysis revealed multiple independent signals at key loci. Gene-based GWAS pinpointed CETP and APOC1 as significant for HDL and LDL, respectively. Rare variant analysis identified significant contribution of loss-of-function missense variants in CETP, TM6SF2, and APOE, in regulating lipid profiles. Associations replicated with consistent directionality in European datasets and Indian adults, reinforcing conserved biology across ancestries and age groups. Functional enrichment analyses emphasized lipid-related pathways and differential expression in liver. These findings lay the foundation for ancestry-informed genetic risk prediction models to identify children at early risk for cardiovascular diseases. Show less

The dysregulation of long-chain noncoding RNAs (lncRNAs) causes several complex human diseases including neurodegenerative disorders across the globe. This study aimed to investigate lncRNA expression profiles of Withania somnifera (WS)-treated human neuroblastoma SK-N-SH cells at different timepoints (3 & 9 h) and concentrations (50 & 100 µg/mL) using RNA sequencing. Differential gene expression analysis showed a total of 4772 differentially expressed lncRNAs, out of which 3971 were upregulated and 801 were downregulated compared to controls. Differential gene expression was observed in dose-dependent (30 upregulated, 25 downregulated, 100 µg/mL 3 h vs. 50 µg/mL 3 h; 36 upregulated, 247 downregulated, 100 µg/mL 9 h vs. 50 µg/mL 9 h) and temporal kinetics (79 upregulated, 64 downregulated, 50 µg/mL 9 h vs. 50 µg/mL 3 h; 22 upregulated, 200 downregulated, 100 µg/mL 9 h vs. 100 µg/mL 3 h). Enrichment analysis showed that modulated lncRNAs were mainly implicated in GPCR ligand binding, HDACs and HATs histones, cellular senescence, cell cycle and post-translational protein modifications. Dysregulated lncRNAs upon WS treatment included BACE1-AS, MALAT1, SNHG1, HOTAIR, MEG3, BDNF-AS, and SHANK2-AS1 which are potential biomarkers in several neurodegenerative diseases. Co-expression analysis revealed that genes such as HMOX1, CHGB, SLC7A11, NOS1, KCNJ and NPY2R may be important in neurodegenerative disorders. Taken together, our results indicated that WS treatment modulated several differentially expressed lncRNAs with putative regulatory potential in various neurodegenerative disorders. To the best of our knowledge, the lncRNA regulome that elicits the health-beneficial effects of WS has not been delineated thus far. Show less

In neurodegenerative diseases, amyloid formation by some proteins cause neuronal damage and loss. To prevent this neuronal damage and loss certain pharmaceuticals are available. Many of these pharmaceuticals act on the neurodegenerative disease symptoms but not on the root cause. This study helps to detect more effective agents which directly act on the root cause and reduce the risk of neurodegenerative diseases. To identify new anti-amyloid agents, the folk medicinally important plant Show less

Dyggve-Melchior-Clausen dysplasia (DMC) and Smith-McCort dysplasia (SMC types 1 and 2) are rare spondyloepimetaphyseal dysplasias with identical radiological findings. The presence of intellectual disability in DMC and normal intellect in SMC differentiates the two. DMC and SMC1 are allelic and caused by homozygous or compound heterozygous variants in Detailed clinical phenotyping and skeletal radiography followed by molecular testing were performed in all affected individuals. Next-generation sequencing and Sanger sequencing were used to confirm 24 affected individuals from seven centres are described. 18 had DMC and 6 had SMC2. Parental consanguinity was present in 15 of 19 (79%). Height <3 SD and gait abnormalities were seen in 20 and 14 individuals, respectively. The characteristic radiological findings of lacy iliac crests and double-humped vertebral bodies were seen in 96% and 88% of the affected. Radiological findings became attenuated with age. 23 individuals harboured biallelic variants in either This large cohort from India contributes to the increasing knowledge of clinical and molecular findings in these rare 'Golgipathies'. Show less

Leucine-rich repeat and immunoglobulin domain-containing protein (Lingo-1) plays a vital role in a large number of neuronal processes underlying learning and memory, which are known to be disrupted in schizophrenia. However, Lingo-1 has never been examined in the context of schizophrenia. The genetic association of a single-nucleotide polymorphism (SNP, rs3144) and methylation (CpG sites) in the Show less

Congenital myasthenic syndromes (CMS) are rare, heterogeneous, and often treatable genetic disorders depending on the underlying molecular defect. We performed a detailed clinical evaluation of seven patients from five unrelated families. Exome sequencing was performed on five index patients. Clinically significant variants were identified in four CMS disease-causing genes: COLQ (3/7), CHRNE (2/7), DOK7 (1/7), and RAPSN (1/7). We identified two novel variants, c.930₉₃₃delCATG in DOK7 and c.1016₁₀₃₂ + 2dup in CHRNE . A common pathogenic variant, c.955-2A>C, has been identified in COLQ -related CMS patients. Homozygosity mapping of this COLQ variant in patients from two unrelated families revealed that it was located in a common homozygous region of 3.2 Mb on chromosome 3 and was likely to be inherited from a common ancestor. Patients with COLQ variants had generalized muscle weakness, those with DOK7 and RAPSN variants had limb-girdle weakness, and those with CHRNE variants had predominant ocular weakness. Patients with COLQ and DOK7 variants showed improvement with salbutamol and CHRNE with pyridostigmine therapy. This study expands the mutational spectrum and adds a small but significant cohort of CMS patients from India. We also reviewed the literature to identify genetic subtypes of CMS in India. Show less

Apolipoprotein A4 (APOA4) is one of the most abundant and versatile apolipoproteins facilitating lipid transport and metabolism. APOA4 is synthesized in the small intestine, packaged onto chylomicrons, secreted into intestinal lymph and transported via circulation to several tissues, including adipose. Since its discovery nearly 4 decades ago, to date, only platelet integrin αIIbβ3 has been identified as APOA4 receptor in the plasma. Using co-immunoprecipitation coupled with mass spectrometry, we probed the APOA4 interactome in mouse gonadal fat tissue, where ApoA4 gene is not transcribed but APOA4 protein is abundant. We demonstrate that lipoprotein receptor-related protein 1 (LRP1) is the cognate receptor for APOA4 in adipose tissue. LRP1 colocalized with APOA4 in adipocytes; it interacted with APOA4 under fasting condition and their interaction was enhanced during lipid feeding concomitant with increased APOA4 levels in plasma. In 3T3-L1 mature adipocytes, APOA4 promoted glucose uptake both in absence and presence of insulin in a dose-dependent manner. Knockdown of LRP1 abrogated APOA4-induced glucose uptake as well as activation of phosphatidylinositol 3 kinase (PI3K)-mediated protein kinase B (AKT). Taken together, we identified LRP1 as a novel receptor for APOA4 in promoting glucose uptake. Considering both APOA4 and LRP1 are multifunctional players in lipid and glucose metabolism, our finding opens up a door to better understand the molecular mechanisms along APOA4-LRP1 axis, whose dysregulation leads to obesity, cardiovascular disease, and diabetes. Show less

Glioblastoma (GBM) has poor median survival due to its resistance to chemoradiotherapy, which results in tumor recurrence. Recurrent GBMs currently lack effective treatments. DUSP6 is known to be pro-tumorigenic and is upregulated in GBM. We show that DUSP6 expression is significantly higher in recurrent GBM patient biopsies compared to expression levels in primary GBM biopsies. Importantly, although it has been reported to be a cytoplasmic protein, we found nuclear localization of DUSP6 in primary and recurrent patient samples and in parent and relapse populations of GBM cell lines generated from an in vitro radiation survival model. DUSP6 inhibition using BCI resulted in decreased proliferation and clonogenic survival of parent and relapse cells. Pharmacological or genetic inhibition of DUSP6 catalytic activity radiosensitized primary and, importantly, relapse GBM cells by inhibiting the recruitment of phosphorylated DNAPKcs (also known as PRKDC), subsequently downregulating the recruitment of phosphorylated histone H2AX (γH2AX) and 53BP1 (also known as TP53BP1). This resulted in decreased cell survival and prolonged growth arrest upon irradiation in vitro and significantly increased the progression-free survival in orthotopic mouse models of GBM. Our study highlights a non-canonical function of DUSP6, emphasizing the potential application of DUSP6 inhibitors in the treatment of recurrent GBM. Show less

Chronic venous diseases, including varicose veins, are characterized by hemodynamic disturbances due to valve defects, venous insufficiency, and orthostatism. Veins are physiologically low shear stress systems, and how altered hemodynamics drives focal endothelial dysfunction and causes venous remodeling is unknown. Here we demonstrate the occurrence of endothelial to mesenchymal transition (EndMT) in human varicose veins. Moreover, the BMP4-pSMAD5 pathway was robustly upregulated in varicose veins. In vitro flow-based assays using human vein, endothelial cells cultured in microfluidic chambers show that even minimal disturbances in shear stress as may occur in early stages of venous insufficiency induce BMP4-pSMAD5-based phenotype switching. Furthermore, low shear stress at uniform laminar pattern does not induce EndMT in venous endothelial cells. Targeting the BMP4-pSMAD5 pathway with small molecule inhibitor LDN193189 reduced SNAI1/2 expression in venous endothelial cells exposed to disturbed flow. TGFβ inhibitor SB505124 was less efficient in inhibiting EndMT in venous endothelial cells exposed to disturbed flow. We conclude that disturbed shear stress, even in the absence of any oscillatory flow, induces EndMT in varicose veins Show less

Central corneal thickness (CCT) is one of the most heritable human traits, with broad-sense heritability estimates ranging between 0.68 to 0.95. Despite the high heritability and numerous previous association studies, only 8.5% of CCT variance is currently explained. Here, we report the results of a multiethnic meta-analysis of available genome-wide association studies in which we find association between CCT and 98 genomic loci, of which 41 are novel. Among these loci, 20 were significantly associated with keratoconus, and one (RAPSN rs3740685) was significantly associated with glaucoma after Bonferroni correction. Two-sample Mendelian randomization analysis suggests that thinner CCT does not causally increase the risk of primary open-angle glaucoma. This large CCT study explains up to 14.2% of CCT variance and increases substantially our understanding of the etiology of CCT variation. This may open new avenues of investigation into human ocular traits and their relationship to the risk of vision disorders. Show less

Rheumatoid arthritis (RA) is a genetically complex disease of immune dysregulation. This study sought to gain further insight into the genetic risk mechanisms of RA by conducting an expression quantitative trait locus (eQTL) analysis of confirmed genetic risk loci in CD4+ T cells and B cells from carefully phenotyped patients with early arthritis who were naive to therapeutic immunomodulation. RNA and DNA were isolated from purified B and/or CD4+ T cells obtained from the peripheral blood of 344 patients with early arthritis. Genotyping and global gene expression measurements were carried out using Illumina BeadChip microarrays. Variants in linkage disequilibrium (LD) with non-HLA RA single-nucleotide polymorphisms (defined as r Genes subject to cis-eQTL effects that were common to both CD4+ and B lymphocytes at RA risk loci were FADS1, FADS2, BLK, FCRL3, ORMDL3, PPIL3, and GSDMB. In contrast, those acting on METTL21B, JAZF1, IKZF3, and PADI4 were unique to CD4+ lymphocytes, with the latter candidate risk gene being identified for the first time in this cell subset. B lymphocyte-specific eQTLs for SYNGR1 and CD83 were also found. At the 8p23 BLK-FAM167A locus, adjacent genes were subject to eQTLs whose activity differed markedly between cell types; in particular, the FAM167A effect displayed striking B lymphocyte specificity. No trans-eQTLs approached experiment-wide significance, and linear modeling did not identify a significant influence of biologic covariates on cis-eQTL effect sizes. These findings further refine the understanding of candidate causal genes in RA pathogenesis, thus providing an important platform from which downstream functional studies, directed toward particular cell types, may be prioritized. Show less

Identity-by-descent mapping using empirical estimates of identity-by-descent allele sharing may be useful for studies of complex traits in founder populations, where hidden relationships may augment the inherent genetic information that can be used for localization. Through identity-by-descent mapping, using ≈400 000 single-nucleotide polymorphisms (SNPs), of serum lipid profiles, we identified a major linkage signal for triglycerides in 1007 Pima Indians (LOD=9.23; Show less

The transient receptor potential melastatin type 6 (TRPM6) epithelial Mg(2+) channels participate in transcellular Mg(2+) transport in the kidney and intestine. Previous reports suggested a hormonal cAMP-dependent regulation of Mg(2+) reabsorption in the kidney. The molecular details of this process are, however, unknown. Adenylate cyclase 3 (Adcy3) has been shown to colocalize with the Na(+)/Cl(-) cotransporter, a marker of the distal convoluted segment of the kidney, the principal site of TRPM6 expression. Given the critical role of TRPM6 in Mg(2+) reabsorption, an inducible kidney-specific Adcy3 deletion mouse model was characterized for blood and urinary electrolyte disturbances under a normal--and low--Mg(2+) diet. Increased urinary Mg(2+) wasting and Trpm6 mRNA levels were observed in the urine and kidney of Adcy3-deleted animals compared with wild-type controls. Serum Mg(2+) concentration was significantly lower in Adcy3-deleted animals at day 7 on the low Mg(2+) diet. Using patch clamp electrophysiology, cell surface biotinylation, and total internal reflection fluorescence live cell imaging of transfected HEK293 cells, we demonstrated that cAMP signaling rapidly potentiates TRPM6 activity by promoting TRPM6 accumulation at the plasma membrane and increasing its single-channel conductance. Comparison of electrophysiological data from cells expressing the phosphorylation-deficient S1252A or phosphomimetic S1252D TRPM6 mutants suggests that phosphorylation at this intracellular residue participates in the observed stimulation of channel activity. Altogether, these data support a physiologically relevant magnesiotropic role of cAMP signaling in the kidney by a direct stimulatory action of protein kinase A on the plasma membrane trafficking and function of TRPM6 ion channels. Show less

Higher HDL-cholesterol (HDL-C) is linked to lower cardiovascular risk but individuals with type 1 diabetes mellitus (T1DM) with normal or high HDL-C have higher cardiovascular events compared to age matched non-diabetic controls (ND). We determined whether altered HDL functions despite having normal HDL-C concentration may explain increased cardiovascular risk in T1DM individuals. We also determined whether irreversible posttranslational modifications (PTMs) of HDL bound proteins occur in T1DM individuals with altered HDL functions. T1DM with poor glycemic control (T1D-PC, HbA1c≥8.5%, n=15) and T1DM with good glycemic control (T1D-GC, HbA1c≤6.6%, n=15) were compared with equal numbers of NDs, ND-PC and ND-GC respectively, matched for age, sex and body mass index (BMI). We measured cholesterol efflux capacity (CEC) of HDL in the serum using J774 macrophages, antioxidant function of HDL as the ability to reverse the oxidative damage of LDL and PON1 activity using commercially available kit. For proteomic analysis, HDL was isolated by density gradient ultracentrifugation and was analyzed by mass spectrometry and shotgun proteomics method. Plasma HDL-C concentrations in both T1DM groups were similar to their ND. However, CEC (%) of T1D-PC (16.9±0.8) and T1D-GC (17.1±1) were lower than their respective ND (17.9±1, p=0.01 and 18.2±1.4, p=0.02). HDL antioxidative function also was lower (p<0.05). The abundance of oxidative PTMs of apolipoproteins involved in CEC and antioxidative functions of HDL were higher in T1D-PC (ApoA4, p=0.041) and T1D-GC (ApoA4, p=0.025 and ApoE, p=0.041) in comparison with ND. Both T1D-PC and T1D-GC groups had higher abundance of amadori modification of ApoD (p=0.002 and p=0.041 respectively) and deamidation modification of ApoA4 was higher in T1D-PC (p=0.025). Compromised functions of HDL particles in T1DM individuals, irrespective of glycemic control, could be explained by higher abundance of irreversible PTMs of HDL proteins. These results lend mechanistic support to the hypothesis that HDL quality rather than quantity determines HDL function in T1DM and suggest that measurements of concentrations of HbA1c and HDL-C are not sufficient as biomarkers of effective treatment to lower cardiovascular risk in T1DM individuals. Show less

Chronic venous disease (CVD) is one of the most prevalent yet underrated disorders worldwide. High heritability estimates of CVD indicate prominent genetic components in its etiology and pathology. Mutations in human forkhead box C2 (FoxC2) gene are strongly associated with valve failure in saphenous and deep veins of lower extremities. We explored the association of genetic variants of FoxC2 as well as FoxC2 mRNA and protein expression levels with CVD of lower limbs. We systematically sequenced the single coding exon, 5' and 3' flanking regions of FoxC2 gene in 754 study subjects which includes 382 patients with CVD and 372 healthy subjects. Four novel and three reported polymorphisms were identified in our cohort. Three variants in 5' flanking region and one in 3' flanking region of FoxC2 gene were significantly associated with CVD risk. FoxC2 mRNA in vein tissues from 22 patients was 4±1.42 fold increased compared to saphenous veins from 20 normal subjects (p<0.01). FoxC2 protein was also significantly upregulated in varicose veins compared to control samples. The c.-512C>T (rs34221221: C>T) variant which is located in the FoxC2 putative promoter region was further analyzed. Functional analysis of c.-512C>T revealed increased mRNA and protein expression in patients with homozygous TT genotype compared to heterozygous CT and wild CC genotypes. Luciferase assay indicated higher transcriptional activity of mutant compared to wild genotype of this variant. These findings suggested that c.-512C>T variant of FoxC2 was strongly associated with susceptibility to CVD and also that this variant resulted in FoxC2 overexpression. To obtain a mechanistic insight into the role of upregulated FoxC2 in varicosities, we overexpressed FoxC2 in venous endothelial cells and observed elevated expression of arterial markers Dll4 and Hey2 and downregulation of venous marker COUP-TFII. Our study indicates altered FoxC2-Notch signaling in saphenous vein wall remodeling in patients with varicose veins. Show less

Fatty acid elongases and desaturases play an important role in hepatic and whole body lipid composition. We examined the role that key transcription factors played in the control of hepatic elongase and desaturase expression. Studies with peroxisome proliferator-activated receptor alpha (PPARalpha)-deficient mice establish that PPARalpha was required for WY14643-mediated induction of fatty acid elongase-5 (Elovl-5), Elovl-6, and all three desaturases [Delta(5) desaturase (Delta(5)D), Delta(6)D, and Delta(9)D]. Increased nuclear sterol-regulatory element binding protein-1 (SREBP-1) correlated with enhanced expression of Elovl-6, Delta(5)D, Delta(6)D, and Delta(9)D. Only Delta(9)D was also regulated independently by liver X receptor (LXR) agonist. Glucose induction of l-type pyruvate kinase, Delta(9)D, and Elovl-6 expression required the carbohydrate-regulatory element binding protein/MAX-like factor X (ChREBP/MLX) heterodimer. Suppression of Elovl-6 and Delta(9)D expression in livers of streptozotocin-induced diabetic rats and high fat-fed glucose-intolerant mice correlated with low levels of nuclear SREBP-1. In leptin-deficient obese mice (Lep(ob/ob)), increased SREBP-1 and MLX nuclear content correlated with the induction of Elovl-5, Elovl-6, and Delta(9)D expression and the massive accumulation of monounsaturated fatty acids (18:1,n-7 and 18:1,n-9) in neutral lipids. Diabetes- and obesity-induced changes in hepatic lipid composition correlated with changes in elongase and desaturase expression. In conclusion, these studies establish a role for PPARalpha, LXR, SREBP-1, ChREBP, and MLX in the control of hepatic fatty acid elongase and desaturase expression and lipid composition. Show less

Asian Indians who have settled overseas and those in urban India have increased risk of coronary events. Reasons for this increased risk are thought to be genetic but are yet unclear. Advances in molecular cardiology have revealed a number of single nucleotide polymorphisms associated with atherosclerosis. In this review, gene polymorphisms that have been associated with coronary diseases among Indians are discussed. Topics include the genes involved in hyperlipidemia, hypertension, and homocysteine. Mutations in the low-density lipoprotein receptor (LDLR) gene resulting in familial hypercholesterolemia have strong association with premature atherosclerosis. Common polymorphism of the apolipoproteins (apo) B-100 and E genes have been associated with variation in lipid and lipoprotein levels. Recently identified polymorphisms in the apoC3 (T-455C, C-482T), and cholesteryl ester transfer protein (CETP) (B1/B2 allele) genes are associated with increased triglycerides and reduced high-density lipoprotein (HDL)-levels, a feature now also common among Asian Indians. Angiotensin-converting enzyme-deletion (DD) polymorphism has been shown to influence beta-blocker therapy in heart failure. Mutations in methylenetetrahydrofolate reductase (C667T), cystathionine beta-synthase (T833C), and methionine synthase (A2756G) genes cause hyperhomocysteinemia, an independent risk factor for atherothrombosis. As the genetics of atherosclerosis continues to evolve, these factors along with the newer emerging factors may become a part of the routine assessment, aiding prediction of future coronary events. Show less