Histone H3 (1-20)

Objective: To investigate the expression of tumor necrosis factor-alpha (TNF-α) and cyclooxygenase-2 (COX-2) mRNA and evaluate the status of histone H3 acetylation at TNF-α and COX-2 promoter in peripheral blood mononuclear cells (PBMCs) from type 2 diabetics. Methods: The PBMCs from 12 type 2 diabetics and 12 healthy controls were isolated by Ficoll-Hypaque density gradient centrifugation. The differential expression of TNF-α and COX-2 mRNA was measured by real-time PCR (polymerase chain reaction). Chromatin immunoprecipitation analysis was used to detect the status of H3 acetylation at TNF-α and COX-2 promoter region. Results: TNF-α and COX-2 mRNA were overexpressed in PBMCs from Type 2 diabetics as compared with normal controls (2.28 ± 0.09 fold and 2.78 ± 0.26 fold).(P < 0.05). Compared with normal controls, H3 acetylation at the TNF-α (1.54 ± 0.43 vs 0.97 ± 0.39, P = 0.0094) and COX-2 (1.20 ± 0.58 vs 0.64 ± 0.21, P = 0.0161) gene promoter region was elevated in PBMCs from Type 2 diabetic patients. Conclusion: Increased H3 acetylation at TNF-α and COX-2 promoter in PBMCs from type 2 diabetics may contribute to the pathogenesis of type 2 diabetes through the elevated expressions of TNF-α and COX-2.

Linker H1 histone is one of the five main histone proteins (H1, H2A, H2B, H3, and H4), which are components of chromatin in eukaryotic cells. Here we have analyzed the patterns of DNA recognition by free H1 histone using a stepwise increase of the ligand complexity method; the affinity of H1 histone for various single- and double-stranded oligonucleotides (d(pN)n; n = 1-20) was evaluated using their competition with 12-mer [32P]labeled oligonucleotide and protein-oligonucleotide complex delaying on nitrocellulose membrane filters. It was shown that minimal ligands of H1 histone (like other DNA-dependent proteins and enzymes) are different mononucleotides (dNMPs; Kd = (1.30 ± 0.2) × 10-2 M). An increase in the length of single-stranded (ss) homo- and hetero-oligonucleotides (d(pA)n, d(pT)n, d(pC)n, and d(pN)n with different bases) by one nucleotide link regardless of their bases, leads to a monotonic increase in their affinity by a factor of f = 3.0 ± 0.2. This factor f corresponds to the Kd value = 1/f characterizing the affinity of one nucleotide of different ss d(pN)n for H1 at n = 2-6 (which are covered by this protein globule) is approximately 0.33 ± 0.02 M. The affinity of five out of six DNA nucleotide units is approximately 25 times lower than for one of the links. The affinity of duplexes of complementary homo- and hetero-d(pN)20 is only 1.3-3.3-fold higher in comparison with corresponding ss oligonucleotides. H1 histone forms mainly weak additive contacts with internucleoside phosphate groups of ssDNAs and one chain of double-stranded DNAs, but not with the bases.

Purpose: MTHFR, one of the major enzymes in the folate cycle, is known to acquire single-nucleotide polymorphisms that significantly reduce its activity, resulting in an increase in circulating homocysteine. Methylation processes are of crucial importance in gametogenesis, involved in the regulation of imprinting and epigenetic tags on DNA and histones. We have retrospectively assessed the prevalence of MTHFR SNPs in a population consulting for infertility according to gender and studied the impact of the mutations on circulating homocysteine levels. Methods: More than 2900 patients having suffered at least two miscarriages (2 to 9) or two failed IVF/ICSI (2 to 10) attempts were included for analysis of MTHFR SNPs C677T and A1298C. Serum homocysteine levels were measured simultaneously. Results: We observed no difference in the prevalence of different genetic backgrounds between men and women; only 15% of the patients were found to be wild type. More than 40% of the patients are either homozygous for one SNP or compound heterozygous carriers. As expected, the C677T SNP shows the greatest adverse effect on homocysteine accumulation. The impact of MTHFR SNPs on circulating homocysteine is different in men than in women. Conclusions: Determination of MTHFR SNPs in both men and women must be seriously advocated in the presence of long-standing infertility; male gametes, from MTHFR SNPs carriers, are not exempted from exerting a hazardous impact on fertility. Patients should be informed of the pleiotropic medical implications of these SNPs for their own health, as well as for the health of future children.