A haplotype variant of the human chromogranin A gene (CHGA) promoter increases CHGA expression and the risk for cardiometabolic disorders

Age and Sex-related Chromogranin A Gene Polymorphisms and its Association with Metabolic Syndrome Components

Introduction

The purpose of this study was to determine the possible differences in genetic polymorphisms and serum levels of chromogranin A (CgA), according to age and sex, in subjects with and without metabolic syndrome (MetS).

Methodology

The genotyping and serum level of CgA and biochemical parameters were measured by the T-ARMS-PCR and PCR-RFLP and ELISA and spectrophotometer methods, respectively.

Results

A comparison of males with and without MetS showed significantly lower high-density lipoprotein-cholesterol (HDL-C) levels than those of females.At ages 30-70 years, both sexes showed significant differences in triglycerides (TG), fasting blood sugar (FBS), CgA levels and waist circumference (WC) when compared to the two groups. Both sexes with MetS indicated significant differences in systolic blood pressure (SBP) at ages 40-70 years, while at ages 40-59 years, there was a significant difference in HDL-C level in males.There was a significant correlation between serum levels of FBS, TG, SBP and WC (in both sexes), and CgA in subjects with MetS. Significant correlation was found between HDL-C level and diastolic blood pressure (DBP), and CgA level in males and females, respectively. CgA genotype frequency (T-415C and C+87T polymorphisms) showed no significant differences between males and females with and without MetS, while there was only a significant difference in frequency of the genotypes T-415C when compared to males with and without MetS.

Conclusion

The CgA appears to be strongly associated with MetS components in both sexes. Variation in CgA gene expression may affect the T-415C polymorphism in males. This may mean that the structure of CgA genetics differs in different ethnic groups. Differences in the serum level and expression of CgA gene may show valuable study results that it may be expected a relationship between these variables and the MetS.

Chromogranin A and its derived peptides: potential regulators of cholesterol homeostasis

Chromogranin A (CHGA), a member of the granin family of proteins, has been an attractive therapeutic target and candidate biomarker for several cardiovascular, neurological, and inflammatory disorders. The prominence of CHGA stems from the pleiotropic roles of several bioactive peptides (e.g., catestatin, pancreastatin, vasostatins) generated by its proteolytic cleavage and by their wide anatomical distribution. These peptides are emerging as novel modulators of cardiometabolic diseases that are often linked to high blood cholesterol levels. However, their impact on cholesterol homeostasis is poorly understood. The dynamic nature of cholesterol and its multitudinous roles in almost every aspect of normal body function makes it an integral component of metabolic physiology. A tightly regulated coordination of cholesterol homeostasis is imperative for proper functioning of cellular and metabolic processes. The deregulation of cholesterol levels can result in several pathophysiological states. Although studies till date suggest regulatory roles for CHGA and its derived peptides on cholesterol levels, the mechanisms by which this is achieved still remain unclear. This review aims to aggregate and consolidate the available evidence linking CHGA with cholesterol homeostasis in health and disease. In addition, we also look at common molecular regulatory factors (viz., transcription factors and microRNAs) which could govern the expression of CHGA and genes involved in cholesterol homeostasis under basal and pathological conditions. In order to gain further insights into the pathways mediating cholesterol regulation by CHGA/its derived peptides, a few prospective signaling pathways are explored, which could act as primers for future studies.

The immunomodulatory functions of chromogranin A-derived peptide pancreastatin

Chromogranin A (CgA) is a 439 amino acid protein secreted by neuroendocrine cells. Proteolytic processing of CgA results in the production of different bioactive peptides. These peptides have been associated with inflammatory bowel disease, diabetes, and cancer. One of the chromogranin A-derived peptides is ∼52 amino acid long Pancreastatin (PST: human (h)CgA250-301, murine (m)CgA263-314). PST is a glycogenolytic peptide that inhibits glucose-induced insulin secretion from pancreatic islet β-cells. In addition to this metabolic role, evidence is emerging that PST also has inflammatory properties. This review will discuss the immunomodulatory properties of PST and its possible mechanisms of action and regulation. Moreover, this review will discuss the potential translation to humans and how PST may be an interesting therapeutic target for treating inflammatory diseases.

A haplotype variant of Hu sheep follicle-stimulating hormone receptor promoter region decreases transcriptional activity

In sheep, increased expression of the follicle-stimulating hormone receptor (FSHR) in the ovary is a common feature of ewes that carry the prolific allele. In this study, we demonstrated that polymorphisms in the core promoter of the FSHR gene are associated with the reproductive performance of Hu sheep and are involved in the transcriptional activity of FSHR. An approximately 1.5-kb region of the 5' flanking sequence of the Hu sheep FSHR gene was isolated and characterized, and its core promoter was located in the 5' regulatory region, from nucleotides -580 to -342. Four variants (c.-518T>C, c.-466C>T, c.-414A>G and c.-365C>T) were detected in this region, and six genotypes and three haplotypes were found in the Hu sheep population (n = 245). An association analysis revealed that these polymorphisms are associated with the litter size of Hu ewes. Furthermore, a luciferase assay showed that the T-C-A-C- and C-T-G-T-type core promoters have higher transcriptional activity than does the T-C-G-C type. Notably, the putative binding site for the transcription factor Yin Yang 1 (YY1) was present at the A allele of nucleotide -414, but YY1 can significantly increase the transcriptional activity of the FSHR core promoter, which contains three different haplotypes. Taken together, our results establish that these variants might be involved in regulating the transcriptional activity of FSHR and litter size in Hu ewes and may provide a novel candidate marker for marker-assisted selection in sheep breeding.