Morpholino-mediated knockdown in primary chondrocytes implicates Hoxc8 in regulation of cell cycle progression

Abstract

Numerous experiments in mutant and transgenic mice have implicated Hox transcription factors in development of the skeletal system, postulating a role for these proteins in cell proliferation of precursor cells and regulation of cell differentiation. Our own data from Hoxc8 and Hoxd4 transgenic mice suggest that Hoxc8 is involved in cell proliferation during cartilage development. In order to directly assess its role in cell proliferation of a specific skeletal cell type, the cartilage-producing chondrocyte, we performed morpholino-mediated knockdown experiments in normal primary chondrocytes. Through analysis of PCNA expression and staining for phosphorylated Histone 3, two cell cycle markers, we show that interference with Hoxc8 expression in chondrocytes reduces cell proliferation, but in the absence of apoptosis. Instead, cells with a knockdown in Hoxc8 expression appear to be delayed in their progression through the cell cycle. Our results provide evidence for prolonged duration of and delayed exit from M-phase, thus implicating a role for Hoxc8 in controlling cell cycle progression at this critical check point.

Identification of microRNAs associated with hyperthermia-induced cellular stress response

“…Of the 55 putative targets, we found that only eight have been empirically validated: miR-378-SUFU, miR-101- MYCN,, and let-7c-TRIM71 (Lewis et al 2003(Lewis et al , 2005Yekta et al 2004;Lee et al 2007;Lin et al 2007;Mitomo et al 2008). Interestingly, many of the 47 remaining putative targets have known CSR functions: proteolysis (miR-101-UBE2A); molecular chaperones (miR-125b-DNAJB2, miR-424-HSPA4L, miR-424-DNAJB4, miR-125b-TTC7A, miR-452-TTC7A, miR-378-TTC7A, miR-378-HSP90AB1, miR-138-CCT5, miR-138-HSPA4L, miR-376a-HSPA6, miR-let-7c-HSPB2, and miR-196a-HSPH1) (Kojima et al 2004;White et al 2005); protein trafficking (miR-125-ZFYVE1); metabolism (miR-382-KYNU, miR-378-KLK4, miR-376a-MAN1C1, miR-let-7c-GALE, and miR-let-7c-RNF20); cell cycle progression (miR-101-MYCN, miR-196a-HOXC8, and miR-196b-HOXC8) (Deraison et al 2007;Kamel et al 2009) (Tables 1 and 2). In addition, several of the annotated TRMs (miR-125b, -138, and -376a) may target AGO2, an integral protein required for miRNA mediated repression (Leung et al 2006) (Tables 1 and 2).…”

Expression profile of long noncoding RNAs in cartilage from knee osteoarthritis patients

“…Another example is SPP1, which is 87 kb upstream of lncRNA HSP90AA4P (4.155568978 fold downregulation) and a likely candidate as the cis-regulated target of HSP90AA4P. It has been reported that HOXC8 regulated the proliferation of chondrocytes by regulating cell cycles and overexpression of HOXC8 could affect cartilage maturation and endochondral ossification 35,36 . In addition, SPP1, which codes for osteopontin, could enhance the pathological mineralization of articular cartilage.…”

HOXC8 Inhibits Androgen Receptor Signaling in Human Prostate Cancer Cells by Inhibiting SRC-3 Recruitment to Direct Androgen Target Genes

“…HOXC8 effects on in vitro surrogate markers of tumorigenesis and progression Overexpression of HOXC genes is associated with prostate cancer (1) and, in the case of HOXC8, increased Gleason grade (22). Recent studies have implicated HOXC8 in the regulation of cell cycle and proliferation (57)(58)(59)(60), apoptosis (58,61), cell differentiation (62-67), cell adhesion (58,61,68), cytoskeleton/motility/migration (61), and tumorigenesis (58,60,61,68,69). On the basis of these reports and the present lack of understanding as to HOXC8 function in prostate carcinogenesis, its effects on in vitro surrogate markers of prostate cell tumorigenicity were examined.…”