Knockdown of protein kinase CK2 blocked gene expression mediated by brain-derived neurotrophic factor-induced serum response element.

One of the principal signaling pathway outcomes from brain-derived neurotrophic factor (BDNF) is the activation of antiapoptotic pathways. In addition to the role of extracellular signal-regulated kinase 1/2 and phosphatidylinositol-3 kinase, BDNF activates protein kinase CK2 to mediate its neuroprotective effect. The inhibition of CK2 activity has been shown to induce apoptosis. Although serum response element (SRE)-mediated transcription has been reported to be activated by BDNF and that the phosphorylation of serum response factor (SRF) by CK2 has been shown to enhance its DNA binding activity, the biological relevance of these interactions remains largely unclear. In the present study, we found that SRE-mediated transcription, CK2 activity, and SRF phosphorylation increased in PC12 cells under BDNF treatment. The transfection of CK2α siRNA blocked the enhancing effect of BDNF on SRE-mediated transcription, SRF phosphorylation, and Mcl-1 gene expression. Moreover, the blockade of CK2 diminished the antiapoptotic effects of BDNF on SRE-mediated transcription, Mcl-1 gene expression, and cell viability under rotenone-induced cytotoxicity. Our data may assist in the development of therapeutic strategies for inhibiting apoptosis during neurodegeneration.

DNMT3L is a regulator of X chromosome compaction and post-meiotic gene transcription.

Previous studies on the epigenetic regulator DNA methyltransferase 3-Like (DNMT3L), have demonstrated it is an essential regulator of paternal imprinting and early male meiosis. Dnmt3L is also a paternal effect gene, i.e., wild type offspring of heterozygous mutant sires display abnormal phenotypes suggesting the inheritance of aberrant epigenetic marks on the paternal chromosomes. In order to reveal the mechanisms underlying these paternal effects, we have assessed X chromosome meiotic compaction, XY chromosome aneuploidy rates and global transcription in meiotic and haploid germ cells from male mice heterozygous for Dnmt3L. XY bodies from Dnmt3L heterozygous males were significantly longer than those from wild types, and were associated with a three-fold increase in XY bearing sperm. Loss of a Dnmt3L allele resulted in deregulated expression of a large number of both X-linked and autosomal genes within meiotic cells, but more prominently in haploid germ cells. Data demonstrate that similar to embryonic stem cells, DNMT3L is involved in an auto-regulatory loop in germ cells wherein the loss of a Dnmt3L allele resulted in increased transcription from the remaining wild type allele. In contrast, however, within round spermatids, this auto-regulatory loop incorporated the alternative non-coding alternative transcripts. Consistent with the mRNA data, we have localized DNMT3L within spermatids and sperm and shown that the loss of a Dnmt3L allele results in a decreased DNMT3L content within sperm. These data demonstrate previously unrecognised roles for DNMT3L in late meiosis and in the transcriptional regulation of meiotic and post-meiotic germ cells. These data provide a potential mechanism for some cases of human Klinefelter's and Turner's syndromes.