Objective-To investigate the largely unknown genetic component of the common lipid disorder, familial combined hyperlipidemia (FCHL)

Objective-Familial combined hyperlipidemia (FCHL) characterized by high serum total cholesterol and/or triglycerides (TGs) is a common dyslipidemia predisposing to coronary artery disease (CAD). Recently, the upstream transcription factor 1 (USF1) was linked and associated with FCHL and TGs in Finnish FCHL families. Here we examined the previously associated rs3737787 SNP in extended Dutch FCHL families (nϭ532) and in a cohort of US subjects who underwent diagnostic coronary angiography (nϭ1533). Methods and Results-In males of the Dutch FCHL families, we observed significant sex-dependent associations between the common allele of rs3737787 and FCHL, TGs, and related metabolic traits (Pϭ0.02 to 0.006). In the U.S. Whites, sex-dependent associations with TGs and related metabolic traits were observed for the common allele of rs3737787 in males (Pϭ0.04 to 0.02) and rare allele in females (Pϭ0.05 to 0.002). This intriguing relationship was further supported by the highly significant genotype x sex interactions observed for TGs in the Dutch and TGs and body mass index (BMI) in U.S. White subjects with CAD (Pϭ0.0005 to 0.00004). Key Words: upstream transcription factor 1 Ⅲ familial combined hyperlipidemia Ⅲ coronary artery disease Ⅲ association Ⅲ lipids F amilial combined hyperlipidemia (FCHL) is a common familial dyslipidemia with a population prevalence of 1% to 2%. 1 Importantly, FCHL is observed in up to 20% of premature coronary artery disease (CAD) patients. 2 In addition to high serum total cholesterol (TC) and triglycerides (TGs), low plasma levels of high-density lipoprotein cholesterol (HDL-C), small dense low-density lipoprotein particles, and elevated apolipoprotein B (apoB) are also often observed in FCHL. 1,2 Association between FCHL and variants of the upstream transcription factor 1 (USF1) located in the FCHL-linked chromosome 1q21 region was originally identified by Pajukanta et al in Finnish FCHL families. 3 Several independent studies have investigated the USF1 variants in samples ascertained for FCHL or risk factors for premature CAD. 2,4 -6 The common allele of rs3737787 or SNPs in linkage disequilibrium (LD) with this SNP were associated with FCHL or one of its component traits in each of these studies. Komulainen et al investigated USF1 variants in a population-based prospective Finnish cohort and observed an association of USF1 with cardiovascular disease and mortality among females, demonstrating a consequence of USF1 at the population level in Finns. 7 In many of these studies, there is evidence of sex specificity, with the common allele of rs3737787 showing strongest evidence for association with high TGs in males. 2,3,7 Interestingly, in females, the minor allele seems to be associated with elevated lipids, as well as cardiovascular disease and mortality. 7 The underlying functional mechanisms explaining this replicated sex specificity are currently unknown. Conclusion-These

Multiple sclerosis (MS) is a chronic disease of the central nervous system responsible for a large portion of neurological disabilities in young adults. Similar to what occurs in numerous complex diseases, both unknown environmental factors and genetic predisposition are required to generate MS. We ascertained a set of 63 Finnish MS families, originating from a high-risk region of the country, to identify a susceptibility gene within the previously established 3.4-Mb region on 17q24. Initial single nucleotide polymorphism (SNP)-based association implicated PRKCA (protein kinase C alpha) gene, and this association was replicated in an independent set of 148 Finnish MS families (p = 0.0004; remaining significant after correction for multiple testing). Further, a dense set of 211 SNPs evenly covering the PRKCA gene and the flanking regions was selected from the dbSNP database and analyzed in two large, independent MS cohorts: in 211 Finnish and 554 Canadian MS families. A multipoint SNP analysis indicated linkage to PRKCA and its telomeric flanking region in both populations, and SNP haplotype and genotype combination analyses revealed an allelic variant of PRKCA, which covers the region between introns 3 and 8, to be over-represented in Finnish MS cases (odds ratio = 1.34, 95% confidence interval 1.07–1.68). A second allelic variant, covering the same region of the PRKCA gene, showed somewhat stronger evidence for association in the Canadian families (odds ratio = 1.64, 95% confidence interval 1.39–1.94). Initial functional relevance for disease predisposition was suggested by the expression analysis: The transcript levels of PRKCA showed correlation with the copy number of the Finnish and Canadian “risk” haplotypes in CD4-negative mononuclear cells of five Finnish multiplex families and in lymphoblast cell lines of 11 Centre d'Etude du Polymorphisme Humain (CEPH) individuals of European origin.

Continuous 24-h nicotinic acid infusion in rats causes FFA rebound and insulin resistance by altering gene expression and basal lipolysis in adipose tissue. Am J Physiol Endocrinol Metab 300: E1012-E1021, 2011. First published March 8, 2011; doi:10.1152/ajpendo.00650.2010.-Nicotinic acid (NA) has been used as a lipid drug for five decades. The lipidlowering effects of NA are attributed to its ability to suppress lipolysis in adipocytes and lower plasma FFA levels. However, plasma FFA levels often rebound during NA treatment, offsetting some of the lipid-lowering effects of NA and/or causing insulin resistance, but the underlying mechanisms are unclear. The present study was designed to determine whether a prolonged, continuous NA infusion in rats produces a FFA rebound and/or insulin resistance. NA infusion rapidly lowered plasma FFA levels (Ͼ60%, P Ͻ 0.01), and this effect was maintained for Ն5 h. However, when this infusion was extended to 24 h, plasma FFA levels rebounded to the levels of saline-infused control rats. This was not due to a downregulation of NA action, because when the NA infusion was stopped, plasma FFA levels rapidly increased more than twofold (P Ͻ 0.01), indicating that basal lipolysis was increased. Microarray analysis revealed many changes in gene expression in adipose tissue, which would contribute to the increase in basal lipolysis. In particular, phosphodiesterase-3B gene expression decreased significantly, which would increase cAMP levels and thus lipolysis. Hyperinsulinemic glucose clamps showed that insulin's action on glucose metabolism was improved during 24-h NA infusion but became impaired with increased plasma FFA levels after cessation of NA infusion. In conclusion, a 24-h continuous NA infusion in rats resulted in an FFA rebound, which appeared to be due to altered gene expression and increased basal lipolysis in adipose tissue. In addition, our data support a previous suggestion that insulin resistance develops as a result of FFA rebound during NA treatment. Thus, the present study provides an animal model and potential molecular mechanisms of FFA rebound and insulin resistance, observed in clinical studies with chronic NA treatment. hypolipidemic drug; free fatty acids; perilipin; phosphodiesterase; triglyceride synthesis; insulin resistance; nicotinic acid receptor; microarray analysis NICOTINIC ACID (NA; or niacin) is a B-group vitamin. In addition to its function as a vitamin, NA, in high doses, has been used as a lipid drug for five decades (6, 21); it produces very desirable effects such as decreasing plasma triglycerides (TG), VLDL, and LDL-cholesterol levels and increasing HDL-cholesterol levels (14,38). Major clinical trials have demonstrated that NA treatment reduces the progression of atherosclerotic cardiovascular disease (9, 18). The lipid-lowering effects of NA have traditionally been attributed to its antilipolytic effect in adipocytes (10). NA binds to and stimulates a G proteincoupled receptor [i.e., GPR109A or HM74A (37, 41)] in the plasma membrane of adipo...

Different onset rates of insulin-induced hypoglycemia use distinct glucosensors to activate sympathoadrenal counterregulatory responses (CRRs). Glucosensory elements in the portal-mesenteric veins are dispensable with faster rates when brain elements predominate, but are essential for responses to the slower-onset hypoglycemia that is common with insulin therapy. Whether a similar rate-associated divergence exists within more expansive brain networks is unknown. Hindbrain catecholamine neurons distribute glycemia-related information throughout the forebrain. We tested in male rats whether catecholaminergic neurons that project to the medial and ventromedial hypothalamus are required for sympathoadrenal CRRs to rapid- and slow-onset hypoglycemia and whether these neurons are differentially engaged as onset rates change. Using a catecholamine-specific neurotoxin and hyperinsulinemic-hypoglycemic clamps, we found that sympathoadrenal CRRs to slow- but not rapid-onset hypoglycemia require hypothalamus-projecting catecholaminergic neurons, the majority of which originate in the ventrolateral medulla. As determined with Fos, these neurons are differentially activated by the two onset rates. We conclude that 1) catecholaminergic projections to the hypothalamus provide essential information for activating sympathoadrenal CRRs to slow- but not rapid-onset hypoglycemia, 2) hypoglycemia onset rates have a major impact on the hypothalamic mechanisms that enable sympathoadrenal CRRs, and 3) hypoglycemia-related sensory information activates hindbrain catecholaminergic neurons in a rate-dependent manner.

With the completion of the Human Genome Project, over 2 million sequence-verified single nucleotide polymorphisms (SNPs) have been deposited in public databases. The challenge has shifted from SNP identification to high-throughput SNP genotyping. Although this has had little impact on molecular diagnostics, it provides the potential for future molecular diagnostics of complex traits to include SNP profiling. Accordingly, efficient, accurate, and flexible SNP genotyping are needed. In addition, the drive for low cost has pushed genotyping reactions toward multiplexing capability. We compared two SNP genotyping techniques: Affymetrix GenFlex Tag array and Pyrosequencing. The reference method was a well-established, solid-phase, single nucleotide extension reaction technique based on tritium detection. Fourteen SNPs were selected from the fine mapping project of a multiple sclerosis locus on chromosome 17q. Using all three techniques and the reference method, the SNPs were analyzed in 96 related individuals. Without extensive optimization, we successfully genotyped 11 of 14 SNPs with both GenFlex and Pyrosequencing. Our study suggests that the Pyrosequencing technique provides higher accuracy between the two systems which is most likely due to the single-stranded template in the extension reaction. Thus, Pyrosequencing has potential for diagnostic applications. Pyrosequencing, however, is not optimal for large SNP profiling analyses wherein multiplexing potential is an advantage.

Hindbrain catecholamine neurons convey gut-derived metabolic signals to an interconnected neuronal network in the hypothalamus and adjacent forebrain. These neurons are critical for short-term glycemic control, glucocorticoid and glucoprivic feeding responses, and glucagon-like peptide 1 (GLP-1) signaling. Here we investigate whether these pathways also contribute to long-term energy homeostasis by controlling obesogenic sensitivity to a high-fat/high-sucrose choice (HFSC) diet. We ablated hindbrain-originating catecholaminergic projections by injecting anti-dopamine-β-hydroxylase-conjugated saporin (DSAP) into the paraventricular nucleus of the hypothalamus (PVH) of male rats fed a chow diet for up to 12 wk or a HFSC diet for 8 wk. We measured the effects of DSAP lesions on food choices; visceral adiposity; plasma glucose, insulin, and leptin; and indicators of long-term ACTH and corticosterone secretion. We also determined lesion effects on the number of carbohydrate or fat calories required to increase visceral fat. Finally, we examined corticotropin-releasing hormone levels in the PVH and arcuate nucleus expression of neuropeptide Y ( Npy), agouti-related peptide ( Agrp), and proopiomelanocortin ( Pomc). DSAP-injected chow-fed rats slowly increase visceral adiposity but quickly develop mild insulin resistance and elevated blood glucose. DSAP-injected HFSC-fed rats, however, dramatically increase food intake, body weight, and visceral adiposity beyond the level in control HFSC-fed rats. These changes are concomitant with 1) a reduction in the number of carbohydrate calories required to generate visceral fat, 2) abnormal Npy, Agrp, and Pomc expression, and 3) aberrant control of insulin secretion and glucocorticoid negative feedback. Long-term metabolic adaptations to high-carbohydrate diets, therefore, require intact forebrain catecholamine projections. Without them, animals cannot alter forebrain mechanisms to restrain increased visceral adiposity.

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