Association of the functional variant in the 3-hydroxy-3-methylglutaryl-coenzyme a reductase gene with low-density lipoprotein-cholesterol in Japanese

Alternative Splicing Regulation in Metabolic Disorders

Alternative splicing (AS) is a fundamental mechanism for enhancing transcriptome diversity and regulating gene expression, crucial for various cellular processes and the development of complex traits. This review examines the role of AS in metabolic disorders, including obesity, weight loss, dyslipidemias, and metabolic syndrome. We explore the molecular mechanisms underlying AS regulation, focusing on the interplay between cis-acting elements and trans-acting factors, and the influence of RNA-binding proteins (RBPs). Advances in high-throughput sequencing and bioinformatics have unveiled the extensive landscape of AS events across different tissues and conditions, highlighting the importance of tissue-specific splicing in metabolic regulation. We discuss the impact of genetic variants on AS, with a particular emphasis on splicing quantitative trait loci (sQTLs) and their association with cardiometabolic traits. The review also covers the regulation of spliceosome components by phosphorylation, the role of m6A modification in AS, and the interaction between transcription and splicing. Additionally, we address the clinical relevance of AS, illustrating how splicing misregulation contributes to metabolic diseases and the potential for therapeutic interventions targeting splicing mechanisms. This comprehensive overview underscores the significance of AS in metabolic health and disease, advocating for further research to harness its therapeutic potential.

Efficacy and safety of statins in ethnic differences: a lesson for application in Indigenous Australian patient care

Although statins are effective in treating high cholesterol, adverse effects do occur with their use. Efficacy and tolerability vary among statins in different ethnic groups. Indigenous Australians have a high risk for cardiovascular and kidney diseases. Prescribing statins to Indigenous Australians with multi-morbidity requires different strategies to increase efficacy and reduce their toxicity. Previous studies have reported that Indigenous Australians are more susceptible to severe statin-induced myopathies. However, there is a lack of evidence in the underlying genetic factors in this population. This review aims to identify: inter-ethnic differences in the efficacy and safety of statins; major contributing factors accounting for any identified differences; and provide an overview of statin-induced adverse effects in Indigenous Australians.

An evolutionarily-conserved promoter allele governs HMG-CoA reductase expression in spontaneously hypertensive rat

3-Hydroxy-3-methyl glutaryl-coenzyme A reductase (Hmgcr) encodes the rate-limiting enzyme in the cholesterol biosynthesis pathway. The regulation of Hmgcr in rat models of genetic hypertension (viz. Spontaneously Hypertensive Rat [SHR] and its normotensive control Wistar/Kyoto [WKY] strain) is unclear. Interestingly, Hmgcr transcript and protein levels are diminished in liver tissues of SHR as compared to WKY. This observation is consistent with the diminished plasma cholesterol level in SHR animals. However, the molecular basis of these apparently counter-intuitive findings remains completely unknown. Sequencing of the Hmgcr promoter in SHR and WKY strains reveals three variations: A-405G, C-62T and a 11 bp insertion (-398_-388insTGCGGTCCTCC) in SHR. Among these variations, A-405G occurs at an evolutionarily-conserved site among many mammals. Moreover, SHR-Hmgcr promoter displays lower activity than WKY-Hmgcr promoter in various cell lines. Transient transfections of Hmgcr-promoter mutants and in silico analysis suggest altered binding of Runx3 and Srebf1 across A-405G site. On the other hand, C-62T and -398_-388insTGCGGTCCTCC variations do not appear to contribute to the reduced Hmgcr promoter activity in SHR as compared to WKY. Indeed, chromatin immunoprecipitation assays confirm differential binding of Runx3 and Srebf1 to Hmgcr promoter leading to reduced expression of Hmgcr in SHR as compared to WKY under basal as well as cholesterol-modulated conditions. Taken together, this study provides, for the first time, molecular basis for diminished Hmgcr expression in SHR animals, which may account for the reduced circulating cholesterol level in this widely-studied model for cardiovascular diseases.

Relationship between Lipid Phenotypes, Overweight, Lipid Lowering Drug Response and KIF6 and HMG-CoA Genotypes in a Subset of the Brisighella Heart Study Population

The existence of genetic traits might explain the susceptibility to develop hypercholesterolemia and the inter-individual differences in statin response. This study was performed to evaluate whether individuals' polymorphisms in HMG-CoA and KIF6 genes are independently associated with hypercholesterolemia, other lipid-associated traits, and statin response in unselected individuals enrolled in the Brisighella heart study (Survey 2012). A total of 1622 individuals, of which 183 under statin medication, were genotyped for a total of five polymorphisms (KIF6 rs20455, rs9471077, rs9462535; HMG-CoA rs3761740, rs3846662). The relationships between the five loci and clinical characteristics were analyzed. The principal basic parameters calculated on 12 h fasting blood included total cholesterol (TC), High Density Lipoprotein Cholesterol (HDL-C), Low-Density Lipoprotein Cholesterol (LDL-C), and triglycerides (TG). Hypercholesterolemia was defined as a TC >200 mg/dL or use of lipid-lowering medication. 965 individuals were characterized by hypercholesterolemia; these subjects were significantly older (p < 0.001), with body mass index (BMI) and waist circumference significantly higher (p < 0.001) compared to the others. HMG-CoA rs3846662 GG genotype was significantly over-represented in the hypercholesterolemic group (p = 0.030). HMG-CoA rs3846662 genotype was associated with the level of TC and LDL-C. Furthermore, in the same subset of untreated subjects, we observed a significant correlation between the KIF6 rs20455 and HDL-C. KIF6 variants were associated with a significantly lower (rs20455) or higher (rs9471077 and rs9462535) risk of obesity, in males only. No association between responsiveness to statins and the polymorphisms under investigation were observed. Our results showed associations between HMG-CoA rs3846662 and KIF6 rs20455 and lipid phenotypes, which may have an influence on dyslipidemia-related events. Moreover, this represents the first study implicating KIF6 variants with obesity in men, and point to the possible involvement of this genetic locus in the known gender-related differences in coronary artery disease.

Effect of HMGCR genetic variation on neuroimaging biomarkers in healthy, mild cognitive impairment and Alzheimer's disease cohorts

Alzheimer's disease (AD) has become a considerable public health issue. The mechanisms underlying AD onset and progression remain largely unclear. 3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) is a strong functional AD candidate gene because it encodes part of the statin-binding domain of the enzyme, which serves as the rate-limiting step in cholesterol synthesis in all mammalian cells. Here, we evaluated the potential role of HMGCR (rs3846662) in AD-related pathology by assessing neuroimaging biomarkers. We enrolled in 812 subjects from the Alzheimer's disease Neuroimaging Initiative dataset. In general, it is possible that HMGCR (rs3846662) could be involved in preventing the atrophy of right entorhinal (P=0.03385) and left hippocampus (P=0.01839) in the follow-up research of two years. What's more, it lowered the drop rate of glucose metabolism in right temporal. We then further validated them in the AD, mild cognitive impairment (MCI), normal control (NC) sub-groups. All the results in the MCI groups confirmed the association. The results of our study indicated that HMGCR (rs3846662) plays a vital role in AD pathology mainly by influencing brain structure and glucose metabolism during AD progression.

Role of rs3846662 and HMGCR alternative splicing in statin efficacy and baseline lipid levels in familial hypercholesterolemia

OBJECTIVES

To assess the contribution of the rs3846662 polymorphism of HMGCR on serum lipid levels and statin efficacy, we measured in vivo HMGCR mRNA and lipid levels in French Canadian individuals affected by heterozygous familial hypercholesterolemia due to the deletion of more than 15 kb of the LDLR gene.

RESULTS

Men and women carrying the AA genotype at rs3846662, and no APOE4 allele, had higher levels of total cholesterol (5.43 vs. 4.58 mmol/l, P<0.05) and LDL-cholesterol (5.20 vs. 4.39 mmol/l, P<0.05) at baseline. However, with regard to statin efficacy, the penetrance of the AA genotype was sex dependent. Indeed, the percentage reduction in LDL-cholesterol upon statin treatment was significantly decreased in women with the AA genotype compared with women without it (38.4 vs. 46.2%, P<0.05), whereas this was not observed in men. Although both men and women bearing the AA genotype showed a higher ratio of full-length HMGCR mRNA/total HMGCR mRNA compared with individuals without it (n=37, P<0.05), overall transcription of HMGCR was decreased and increased in men and women carrying this genotype, respectively (n=37, P<0.01 and P<0.05). Finally, in our familial hypercholesterolemia cohort, HMGCR alternative splicing explained between 22 and 55% of the variance in statin response.

CONCLUSION

rs3846662 polymorphism and the alternative splicing of HMGCR mRNA significantly impact women's response to statin therapy.

Effects of rs3846662 Variants on HMGCR mRNA and Protein Levels and on Markers of Alzheimer's Disease Pathology

3-Hydroxy-3-methyglutaryl coenzyme A reductase (HMGCR) is a cholesterol-regulating gene with statin relevance. rs3846662 being involved in regulation of HMGCR alternative splicing, we explored its impact on HMGCR messenger RNA (mRNA) and protein levels in the brain and the associations between those levels and levels of Alzheimer's disease pathological markers. We used brain samples derived from a cohort of 33 non-demented controls and 90 Alzheimer's disease autopsied-confirmed cases. HMGCR mRNA levels were determined in the frontal cortex (n = 114) and cerebellum (n = 110) using Taqman-qPCR, and HMGCR protein levels were determined in the frontal cortex (n = 117) using a commercial enzyme immunoassay. While densities of neurofibrillary tangles and senile plaques were determined in the frontal cortex (n = 74), total tau, phosphorylated Tau, and beta-amyloid 1-42 levels were determined in the frontal cortex (n = 94) and cerebellum (n = 91) using commercial enzyme immunoassays. Despite an increase in full-length HMGCR mRNA ratio in the frontal cortex of women carrying the AA genotype, there were no associations between rs3846662 and HMGCR mRNA or protein levels. An increased Δ13 HMGCR mRNA ratio was associated with increased levels of HMGCR proteins and neurofibrillary tangles in the frontal cortex but with reduced beta-amyloid 1-42 levels in the cerebellum, suggesting a brain cell type- or a disease progression-dependent association.

Genetic Contribution of Variants near SORT1 and APOE on LDL Cholesterol Independent of Obesity in Children

Objective

To assess potential effects of variants in six lipid modulating genes (SORT1, HMGCR, MLXIPL, FADS2, APOE and MAFB) on early development of dyslipidemia independent of the degree of obesity in children, we investigated their association with total (TC), low density lipoprotein (LDL-C), high density lipoprotein (HDL-C) cholesterol and triglyceride (TG) levels in 594 children. Furthermore, we evaluated the expression profile of the candidate genes during human adipocyte differentiation.

Results

Expression of selected genes increased 10¹ to >10⁴ fold during human adipocyte differentiation, suggesting a potential link with adipogenesis. In genetic association studies adjusted for age, BMI SDS and sex, we identified significant associations for rs599839 near SORT1 with TC and LDL-C and for rs4420638 near APOE with TC and LDL-C. We performed Bayesian modelling of the combined lipid phenotype of HDL-C, LDL-C and TG to identify potentially causal polygenic effects on this multi-dimensional phenotype and considering obesity, age and sex as a-priori modulating factors. This analysis confirmed that rs599839 and rs4420638 affect LDL-C.

Conclusion

We show that lipid modulating genes are dynamically regulated during adipogenesis and that variants near SORT1 and APOE influence lipid levels independent of obesity in children. Bayesian modelling suggests causal effects of these variants.

Low-density lipoprotein cholesterol, apolipoprotein B, and risk of coronary heart disease: from familial hyperlipidemia to genomics

Coronary heart disease (CHD) affects 17 million people in the United States and accounts for over a million hospital stays each year. Technological advances, especially in genetics and genomics, have changed our understanding of the risk factors for developing CHD. The purpose of this article is to review low-density lipoprotein cholesterol (LDL-C), apolipoprotein B (apo B), and risk of CHD. The article focuses on five topics: (1) a description of lipoprotein classes, normal lipoprotein metabolism, and the biological mechanism of atherosclerosis; (2) a review of selected epidemiologic and clinical trial studies examining the associations between elevated LDL-C and apo B with CHD; (3) a brief review of the familial forms of hyperlipidemia; (4) a description of variants in genes that have been associated with higher LDL-C levels in candidate gene studies and genome-wide association studies (GWAS); and (5) nursing implications, including a discussion on how genetic tests are evaluated and the current clinical utility and validity of genetic tests for CHD.

Evaluation of the global association between cholesterol-associated polymorphisms and Alzheimer's disease suggests a role for rs3846662 and HMGCR splicing in disease risk

BACKGROUND

Recent genome-wide association studies (GWAS) have identified single nucleotide polymorphisms (SNP)s that are essentially unequivocally associated with peripheral cholesterol. Since the alleles of the APOE gene, which modulate peripheral cholesterol metabolism, and midlife plasma cholesterol are both associated with Alzheimer's disease (AD) risk, we have evaluated the hypothesis that SNPs associated with plasma cholesterol are also associated with AD.

RESULTS

Seventeen non-APOE SNPs reproducibly associated with cholesterol per GWAS were tested for association with AD in ~2,000 AD and ~4,000 non-AD subjects. As a group, these SNPs are associated with AD. Two SNPs in particular, rs3846662 and rs1532085, are associated with AD risk and age-of-onset. Additionally, rs3846662 was associated with HMGCR exon 13 splicing in human liver but not brain, possibly obscured by CNS cell-type heterogeneity. However, rs3846662 was associated with HMGCR exon 13 splicing in liver- and brain-derived cell lines.

CONCLUSIONS

Cholesterol-associated SNPs outside of APOE confer a global risk for AD. Rs3846662 and rs1532085 are associated with both AD risk and age-of-onset. Rs3846662 is associated with HMGCR exon 13 inclusion. Since rs3846662 affects AD risk and age-of-onset as well as statin responsiveness, this SNP may confound clinical trials evaluating the protective effects of statins on AD.

Mechanisms and genetic determinants regulating sterol absorption, circulating LDL levels, and sterol elimination: implications for classification and disease risk

This review integrates historical biochemical and modern genetic findings that underpin our understanding of the low-density lipoprotein (LDL) dyslipidemias that bear on human disease. These range from life-threatening conditions of infancy through severe coronary heart disease of young adulthood, to indolent disorders of middle- and old-age. We particularly focus on the biological aspects of those gene mutations and variants that impact on sterol absorption and hepatobiliary excretion via specific membrane transporter systems (NPC1L1, ABCG5/8); the incorporation of dietary sterols (MTP) and of de novo synthesized lipids (HMGCR, TRIB1) into apoB-containing lipoproteins (APOB) and their release into the circulation (ANGPTL3, SARA2, SORT1); and receptor-mediated uptake of LDL and of intestinal and hepatic-derived lipoprotein remnants (LDLR, APOB, APOE, LDLRAP1, PCSK9, IDOL). The insights gained from integrating the wealth of genetic data with biological processes have important implications for the classification of clinical and presymptomatic diagnoses of traditional LDL dyslipidemias, sitosterolemia, and newly emerging phenotypes, as well as their management through both nutritional and pharmaceutical means.

Effect of HMGCR variant alleles on low-density lipoprotein cholesterol-lowering response to atorvastatin in healthy Korean subjects

The investigators quantified the relationship between the genetic polymorphism of HMGCR (3-hydroxy-3-methylglutaryl coenzyme A reductase) and the low-density lipoprotein cholesterol (LDL-C)-lowering effects of atorvastatin in a prospective clinical study. Twenty-four healthy participants were grouped into HMGCR rs3846662 GG (n = 13) and AA (n = 11) genotypes and given atorvastatin (20 mg/d) for 14 days. Serum levels of LDL-C, high-density lipoprotein cholesterol, total cholesterol, triglycerides, and creatinine kinase (CK) were measured before (day 1) and 7, 13, 14, 15, 16, 21, and 28 days after dosing initiation. Blood samples for pharmacokinetics were taken on days 14 through 16. The levels of LDL-C in the GG group were significantly higher than in the AA group at all observation times, with mean differences of 18% to 33% (P < .05). The area under the LDL-C-time curve and the minimum value of LDL-C in the GG group were 24% and 23% higher than in the AA group, respectively (P < .01). There was no significant difference in other lipids, CK, and pharmacokinetic parameters. The HMGCR rs3846662 GG genotype was quantitatively documented to be a significant determinant for higher LDL-C level in basal state and possibly in response to atorvastatin.

Confirmation of ALDH2 as a Major locus of drinking behavior and of its variants regulating multiple metabolic phenotypes in a Japanese population

BACKGROUND

Normative alcohol use (or drinking behavior) influences the risk of cardiovascular disease in a multi-faceted manner. To identify susceptibility gene variants for drinking behavior, a 2-staged genome-wide association study was performed in a Japanese population.

METHODS AND RESULTS

In the stage-1 scan, 733 cases and 729 controls were genotyped with 456,827 SNP markers. The associated loci without redundancy of linkage disequilibrium were further examined in the stage-2 general population panel comprising 2,794 drinkers (≥ once per week), 1,521 chance drinkers (< once per week), and 1,351 non-drinkers. Along with genome-wide exploration, we aimed to replicate the trait association of a candidate gene SNP previously reported (rs1229984 in ADH1B). A cluster of 12 SNPs on 12q24 were found to significantly (P<5×10(-8)) associate with drinking behavior in stage 1, among which rs671 (a Glu-to-Lys substitution at position 504) in the ALDH2 gene showed the strongest association (odds ratio (OR)=0.16, P=3.6×10(-211) in the joint analysis). The association was also replicated for rs1229984 (OR=1.20, P<3.6×10(-4)). Furthermore, ALDH2 504Lys was associated with several metabolic traits, eg, lower levels of high-density lipoprotein cholesterol and liver enzymes-AST, ALT, and γGTP-by interacting with alcohol intake.

CONCLUSIONS

Our results confirm ALDH2 as a major locus regulating drinking behavior in the Japanese, indicating that the ALDH2 504Lys variant exerts pleiotropic effects on risk factors of cardiovascular disease among drinkers.