Evolutionary journey of the Gc protein (vitamin D-binding protein) across vertebrates

With so many diverse functions such as transporter of vitamin D metabolites and fatty acids, actin scavenger and macrophage activating factor, Gc must have been one of the most conserved proteins in animal kingdom. Our objective was to investigate the evolution of Gc by analyzing its differences at protein level. Using BLAST (Basic Local Alignment Search Tool) searches, Gc amino acid sequences were analyzed for homology. Clustal W2 and Jalview were used for multiple sequence alignment analysis, phylogenetic tree by PhyML 3.0 while Batch Web CD-Search Tool was used for identification for conserved domains within protein sequences. Gc protein percent identity between human and rabbit was 83%, which decreased to 81% with cow, 78% with mouse, 76% with rat, 51% with chicken, 41% with frog and 28% with zebrafish. Phylogram showed that rat Gc was the most diverged, while chicken Gc was the most conserved protein. Analysis also indicated high homology among mammals (human, rabbit, cow, rat, and mouse). Gc is a highly conserved protein in chicken and zebrafish. However, the distance from ancestral protein gradually increased in amphibian (frog) and mammals (human, rabbit, cow, rat, and mouse). Human Gc and rabbit Gc appear to be recently evolved proteins. There appears to be an interesting evolutionary pattern- chicken Gc has the least distance from the ancestral protein, while rat Gc is the most diverged. There is no vertebrate devoid of Gc which is suggestive of its important role in vitamin D metabolism in vertebrates

Association of vitamin D binding protein genotype IF-IF with vitamin D levels in male Pakistani population

Objective/ Introduction: As it is widely known that low levels of vitamin D [25(OH)D] are a risk factor in a number of communicable and non-communicable diseases, we wanted to evaluate its role in patients suffering from acute myocardial infarction and healthy controls. We also wanted to investigate the association of vitamin D binding protein (VDBP) genotypes with serum levels of 25(OH)D in this cohort. Methods: We recruited 265 adult males (119 healthy individuals, 146 patients) with the age range of 19-64 years from the National Institute of Cardiovascular Diseases and personnel of the Aga Khan University. DNA was extracted from EDTA blood by salting out method. Gc genotyping was performed by PCR-RFLP (Polymerase Chain Reaction- Restriction Fragment Length Polymorphism). 25(OH)D, alkaline phosphatase, calcium and phosphate levels were analyzed by biochemical kits. All statistical analyses were carried out on SPSS version 19. Results: The mean 25 (OH)D level was 13.95 ± 13.72 ng/ml. Overall vitamin D deficiency (25(OH) D levels \u3c 20 ng/ml) among males was 75.4%, while sufficiency (25(OH) D levels \u3e 30 ng/ml) was only 9.5%. Linear regression analysis revealed that the males with Gc1F-1F genotype have on the average 14.14 ng/ml higher 25(OH)D levels compared to males with 1S-1S genotype after adjusting for age (r2= 0.085, p \u3c0.0005). Age, alkaline phosphatase and calcium were not correlated with 25(OH)D levels (p \u3e0.20 ). However, we found that phosphate levels were positively correlated with vitamin D levels (r= 0.195, p = 0.002). Conclusion: There is a high prevalence of vitamin D deficiency in a Pakistani male population of AMI patients and healthy controls. A positive association of Gc wild type genotype (IF-IF) with 25 (OH)D levels indicates that regulation of 25(OH)D levels in adult males is influenced by variation in VDBP gene. Keywords: Myocardial Infarction, vitamin D, Vitamin D binding protein, Gc genotyp