Null mutation in hormone-sensitive lipase gene and risk of type 2 diabetes.

BACKGROUND: Lipolysis regulates energy homeostasis through the hydrolysis of intracellular triglycerides and the release of fatty acids for use as energy substrates or lipid mediators in cellular processes. Genes encoding proteins that regulate energy homeostasis through lipolysis are thus likely to play an important role in determining susceptibility to metabolic disorders. METHODS: We sequenced 12 lipolytic-pathway genes in Old Order Amish participants whose fasting serum triglyceride levels were at the extremes of the distribution and identified a novel 19-bp frameshift deletion in exon 9 of LIPE, encoding hormone-sensitive lipase (HSL), a key enzyme for lipolysis. We genotyped the deletion in DNA from 2738 Amish participants and performed association analyses to determine the effects of the deletion on metabolic traits. We also obtained biopsy specimens of abdominal subcutaneous adipose tissue from 2 study participants who were homozygous for the deletion (DD genotype), 10 who were heterozygous (ID genotype), and 7 who were noncarriers (II genotype) for assessment of adipose histologic characteristics, lipolysis, enzyme activity, cytokine release, and messenger RNA (mRNA) and protein levels. RESULTS: Carriers of the mutation had dyslipidemia, hepatic steatosis, systemic insulin resistance, and diabetes. In adipose tissue from study participants with the DD genotype, the mutation resulted in the absence of HSL protein, small adipocytes, impaired lipolysis, insulin resistance, and inflammation. Transcription factors responsive to peroxisome-proliferator-activated receptor γ (PPAR-γ) and downstream target genes were down-regulated in adipose tissue from participants with the DD genotype, altering the regulation of pathways influencing adipogenesis, insulin sensitivity, and lipid metabolism. CONCLUSIONS: These findings indicate the physiological significance of HSL in adipocyte function and the regulation of systemic lipid and glucose homeostasis and underscore the severe metabolic consequences of impaired lipolysis. (Funded by the National Institutes of Health and others).

The functional G143E variant of carboxylesterase 1 is associated with increased clopidogrel active metabolite levels and greater clopidogrel response.

INTRODUCTION: Carboxylesterase 1 (CES1) is the primary enzyme responsible for converting clopidogrel into biologically inactive carboxylic acid metabolites. METHODS: We genotyped a functional variant in CES1, G143E, in participants of the Pharmacogenomics of Anti-Platelet Intervention (PAPI) study (n=566) and in 350 patients with coronary heart disease treated with clopidogrel, and carried out an association analysis of bioactive metabolite levels, on-clopidogrel ADP-stimulated platelet aggregation, and cardiovascular outcomes. RESULTS: The levels of clopidogrel active metabolite were significantly greater in CES1 143E-allele carriers (P=0.001). Consistent with these findings, individuals who carried the CES1 143E-allele showed a better clopidogrel response as measured by ADP-stimulated platelet aggregation in both participants of the PAPI study (P=0.003) and clopidogrel-treated coronary heart disease patients (P=0.03). No association was found between this single nucleotide polymorphism and baseline measures of platelet aggregation in either cohort. CONCLUSION: Taken together, these findings suggest, for the first time, that genetic variation in CES1 may be an important determinant of the efficacy of clopidogrel.

Spaced administration of PA32540 and clopidogrel results in greater platelet inhibition than synchronous administration of enteric-coated aspirin and enteric-coated omeprazole and clopidogrel.

BACKGROUND: A common regimen for patients requiring dual-antiplatelet therapy who are at risk for gastrointestinal complications is the synchronous administration of enteric-coated (EC) aspirin, a proton pump inhibitor, and clopidogrel, although proton pump inhibitors have the potential for pharmacodynamic interaction with clopidogrel. Spaced administration of a clopidogrel and a single-tablet formulation of aspirin and immediate-release omeprazole (PA32540) was considered as an alternative that might reduce this potential pharmacodynamic interaction. METHODS AND RESULTS: A randomized, open-label, crossover study was conducted in healthy subjects (n = 30). Two 7-day treatments were separated by 14-day washout periods: (a) PA32540 + clopidogrel (300 mg loading/75 mg maintenance) 10 hours later and (b) synchronous dosing of clopidogrel + EC aspirin (81 mg) + EC omeprazole (40 mg). The primary end point was the inhibition of platelet aggregation (20 µM adenosine diphosphate, maximal extent) after 7 days. CYP2C19 and ABCB1 genotypes were determined. Inhibition of platelet aggregation was greater with spaced PA32540 + clopidogrel therapy vs synchronous clopidogrel + EC aspirin + EC omeprazole therapy (P = .004). There was no difference in day 7 arachidonic acid-induced aggregation. The effect of spacing on pharmacodynamics was independent of genotype. CONCLUSIONS: PA32540 and clopidogrel spaced 10 hours apart had greater antiplatelet effects than did synchronously administered EC aspirin (81 mg), clopidogrel (75 mg), and EC omeprazole in healthy volunteers. These finding are directly relevant to the treatment for patients with high gastrointestinal risk who require dual-antiplatelet therapy and gastroprotection.

Genome-wide association study identifies genetic variants in GOT1 determining serum aspartate aminotransferase levels.

We carried out a genome-wide association study of serum aspartate aminotransferase (AST) activity in 866 Amish participants of the Heredity and Phenotype Intervention Heart Study and identified significant association of AST activity with a cluster of single nucleotide polymorphisms located on chromosome 10q24.1 (peak association was rs17109512; P=2.80E-14), in the vicinity of GOT1, the gene encoding cytosolic AST (cAST). Sequencing of GOT1 revealed an in-frame deletion of three nucleic acids encoding asparagine at position 389 c.1165_1167delAAC (p.Asn389del) in the gene. Deletion carriers had significantly lower AST activity levels compared with homozygotes for the common allele (mean±s.d.: 10.0±2.8 versus 18.8±5.2 U l(-1); P=2.80E-14). Further genotyping of the deletion in other Amish samples (n=1932) identified an additional 20 carriers (minor allele frequency (MAF)=0.0052). The deletion was not detected in 647 outbred Caucasians. Asn at codon 389 is conserved among known mammalian cASTs. In vitro transient transfection of wild-type and mutant cAST indicated that mutant cAST protein was barely detectable in the cells. Furthermore, even after correction for cAST expression, mutant cAST had markedly diminished enzymatic activity. Remarkably, we did not find any association between the deletion and metabolic traits including serum fasting glucose or insulin, fasting and post-meal lipids, inflammatory markers, or sub-clinical markers of cardiovascular disease. In conclusion, we discovered a rare in-frame deletion in GOT1 gene, which inactivates cAST enzyme in the Old Order Amish. This finding will help us to understand structure and function of the enzyme and would be useful for predicting serum AST levels.

Gene Expression Differences Between Offspring of Long-Lived Individuals and Controls in Candidate Longevity Regions: Evidence for PAPSS2 as a Longevity Gene.

Although there is compelling evidence for a genetic contribution to longevity, identification of specific genes that robustly associate with longevity has been a challenge. In order to identify longevity-enhancing genes, we measured differential gene expression between offspring of long-lived Amish (older than 90 years; cases, n = 128) and spouses of these offspring (controls, n = 121) and correlated differentially expressed transcripts with locations of longevity-associated variants detected in a prior genome-wide association study (GWAS) of survival to age 90. Expression of one of these transcripts, 3'-phosphoadenosine 5'-phosphosulfate synthase 2 (PAPSS2), was significantly higher in offspring versus controls (4×10(-4)) and this association was replicated using quantitative real-time polymerase chain reaction. PAPSS2, a sulfation enzyme located on chromosome 10, is ~80kb upstream of the PAPSS2 transcription start site. We found evidence of cis-expression for the originally reported GWAS SNP and PAPSS2 Monogenic conditions linked to PAPSS2 include andrenocortical androgen excess resulting in premature pubarche and skeletal dysplasias, both of which have premature aging features. In summary, these findings provide novel evidence for PAPSS2 as a longevity locus and illustrate the value of harnessing multiple "-omic" approaches to identify longevity candidates.