The mammalian innate immune system is activated by foreign nucleic acids. Detection of double-stranded DNA (dsDNA) in the cytoplasm triggers characteristic antiviral responses and macrophage cell death. Cytoplasmic dsDNA rapidly activated caspase 3 and caspase 1 in bone marrow-derived macrophages. We identified the HIN-200 family member and candidate lupus susceptibility factor, p202, as a dsDNA binding protein that bound stably and rapidly to transfected DNA. Knockdown studies showed p202 to be an inhibitor of DNA-induced caspase activation. Conversely, the related pyrin domain-containing HIN-200 factor, AIM2 (p210), was required for caspase activation by cytoplasmic dsDNA. This work indicates that HIN-200 proteins can act as pattern recognition receptors mediating responses to cytoplasmic dsDNA.

G9a is an epigenetic regulator that methylates H3K9, generally causing repression of gene expression, and participates in diverse cellular functions. G9a is genetically deregulated in a variety of tumor types and can silence tumor suppressor genes and, therefore, is important for carcinogenesis. Although hypoxia is recognized to be an adverse factor in tumor growth and metastasis, the role of G9a in regulating gene expression in hypoxia has not been described extensively. Here, we show that G9a protein stability is increased in hypoxia via reduced proline hydroxylation and, hence, inefficient degradation by the proteasome. This inefficiency leads to an increase in H3K9me2 at its target promoters. Blocking the methyltransferase activity of G9a inhibited cellular proliferation and migration in vitro and tumor growth in vivo. Furthermore, an increased level of G9a is a crucial factor in mediating the hypoxic response by down-regulating the expression of specific genes, including ARNTL, CEACAM7, GATA2, HHEX, KLRG1, and OGN. This down-regulation can be rescued by a small molecule inhibitor of G9a. Based on the hypothesis that the changes in gene expression would influence patient outcomes, we have developed a prognostic G9a-suppressed gene signature that can stratify breast cancer patients. Together, our findings provide an insight into the role G9a plays as an epigenetic mediator of hypoxic response, which can be used as a diagnostic marker, and proposes G9a as a therapeutic target for solid cancers.

Background: Histone deacetylase (HDAC) inhibitors reduce LPS-induced inflammatory mediator production from macrophages, but the relevant HDAC targets are unknown. Results: A specific isoform of Hdac7 amplifies expression of LPS-inducible genes via a HIF-1␣-dependent mechanism in macrophages. Conclusion:The class IIa HDAC Hdac7 promotes inflammatory responses in macrophages. Significance: Hdac7 may be a viable target for developing new anti-inflammatory drugs.

SHBG (sex hormone binding globulin) transports androgens and estrogens in the blood of vertebrates including fish. Orthologs of SHBG in fish are poorly defined, and we have now obtained a zebrafish SHBG cDNA and characterized the zebrafish SHBG gene and protein through molecular biological, biochemical, and informatics approaches. Amino-terminal analysis of zebrafish SHBG indicated that its deduced precursor sequence includes a 25-residue secretion polypeptide and exhibits 22-27% homology with mammalian SHBG sequences and 41% with a deduced fugufish SHBG sequence. The 356-residue mature zebrafish SHBG (39,243 Da) sequence comprises a tandem repeat of laminin G-like domains typical of SHBG sequences; contains three N-glycosylation sites; and exists as a 105,000 +/- 8700 Da homodimer. Zebrafish SHBG exhibits a high affinity and specificity for sex steroids. An RT-PCR indicated that SHBG mRNA first appears in zebrafish larva, and SHBG mRNA was localized within the liver and gut at this stage of development by whole-mount in situ hybridization. In adult fish, SHBG mRNA was found in liver, testis, and gut. In the liver, immunoreactive SHBG was present in hepatocytes and concentrated in intrahepatic bile duct cells, whereas in the testis it was confined to cells surrounding the seminiferous tubule cysts. In the intestine, immunoreactive SHBG was present in the stroma and epithelial cells of the villous projections and the surrounding muscle. The production and presence of SHBG in the gut of developing and adult zebrafish suggests a novel role for this protein in regulating sex steroid action at this site.