Investigating the association between vitamin D dietary intake during pregnancy and incidence of clubfoot in neonates.

AIMS: Talipes equinovarus (clubfoot) is a congenital lower foot deformity that results from a neuromuscular deficiency, but the precise etiology remains elusive. Vitamin D is important for fetal neuromuscular development. In this study, we investigated the association between dietary vitamin D intake during pregnancy and incidence of clubfoot in neonates, since such a question has thus far been overlooked. METHODS: We conducted a secondary analysis of data collected in the United States, between 2007 and 2011 for a case-control study of children born with clubfoot. Participating mothers were interviewed by telephone about dietary and other health and life-style indicators. Exposure to vitamin D was recorded as the average daily intake of dietary vitamin D over a period of 6 months before pregnancy began. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using logistic regression. RESULTS: The dataset included 2667 study participants, of which 663 were cases. Logistic regression showed no significant association between dietary vitamin D or log10 (Vitamin D) intake during pregnancy and incidence of clubfoot in neonates (OR = 1.00, CI = 1.00-1.00, OR = 1.51, CI = 0.83-2.82, respectively). No interaction in the regression model was found between vitamin D and other predictor variables. Results were not confounded by supplement intake of vitamin D during pregnancy. CONCLUSIONS: Results show no evidence of an association between dietary vitamin D intake and incidence of clubfoot in neonates. The lack of association is not confounded by consumption of vitamin D supplements during pregnancy.

Molecular dynamics simulations suggest changes in electrostatic interactions as a potential mechanism through which serine phosphorylation inhibits DNA polymerase ß activity.

DNA polymerase ß is a 39 kDa enzyme that is a major component of Base Excision Repair in human cells. The enzyme comprises two major domains, a 31 kDa domain responsible for the polymerase activity and an 8 kDa domain, which bind ssDNA and has a deoxyribose phosphate (dRP) lyase activity. DNA polymerase ß was shown to be phosphorylated in vitro with protein kinase C (PKC) at serines 44 and 55 (S44 and S55), resulting in loss of its polymerase enzymic activity, but not its ability to bind ssDNA. In this study, we investigate the potential phosphorylation-induced structural changes for DNA polymerase ß using molecular dynamics simulations. The simulations show drastic conformational changes of the polymerase structure as a result of S44 phosphorylation. Phosphorylation-induced conformational changes transform the closed (active) enzyme structure into an open one. Further analysis of the results points to a key hydrogen bond and newly formed salt bridges as potential drivers of these structural fluctuations. The changes observed with S55/44 and S55 phosphorylation were less dramatic and the integrity of the H-bond was not compromised. Thus the phosphorylation of S44 is the major contributor to structural fluctuations that lead to loss of enzymatic activity.

Three steps to cancer: how phosphorylation of tubulin, tubulin tyrosine ligase and P-glycoprotein may generate and sustain cancer.

Transformed cells progress to cancer because they are not eliminated by apoptosis. In this brief minireview I propose, based on published data, that the cell possesses a 'last check point' (LCP) apoptotic step in the form of assembly of nitrotyrosinated alpha-tubulin onto microtubules. This leads to microtubule dysfunction and ultimately apoptosis. I also propose that cells that escape this LCP apoptotic step develop into cancer. Phosphorylation of tubulin tyrosine ligase (TTL) is postulated to cause escape from LCP apoptosis. Phosphorylation also ensures that cancer cells survive a hostile milieu (e.g. chemotherapy).

DNA polymerase beta.

Mammalian DNA polymerase beta(beta-pol) is a single polypeptide chain enzyme of 39kDa. beta-pol has enzymatic activities appropriate for roles in base excision repair and other DNA metabolism events involving gap-filling DNA synthesis. Many crystal structures of beta-pol complexed with dNTP and DNA substrates have been solved, and mouse fibroblast cell lines deleted in the beta-pol gene have been examined. These approaches have enhanced our understanding of structural and functional aspects of beta-pol's role in protecting genomic DNA.