Shinobu Gamou | PubMed Health

PubMed2006

DMRT-1 expression during NEC8 human embryonic carcinoma cell differentiation.

To elucidate the relationship between dsx and mab-3 related transcription factor 1 (Dmrt-1) and differentiation, alteration in mRNA levels during differentiation of NEC8 human embryonic carcinoma cells was investigated. After stimulation with 50 nM phorbol 12-myristate 13-acetate (PMA), the cells differentiated into cells with mesenchymal characteristics and upregulated Dmrt-1 mRNA, possibly through the protein kinase C/mitogen-activated protein kinase/activated protein-1 signaling pathway. Conversely, knockdown of Dmrt-1 by small interfering RNA resulted in cell morphology that was different from that after PMA treatment. These results indicated that Dmrt-1 expression was apparently associated with the differentiation of NEC8, and this cell line may be a helpful in vitro tool to clarify the role of Dmrt-1 in the differentiation process.

Adaptor Proteins, Signal Transducing↗

PubMed2005

Valosine-containing proteins (VCP) in an annelid: identification of a novel spermatogenesis related factor.

Two cDNAs similar to mammalian valosine-containing proteins (VCPs) were isolated from the common lumbricid earthworm Eisenia fetida (Savigny, 1826). The primary sequences, referred to as eVCP-1 and eVCP-2, display a similarity of 74%. Despite of the variable C-termini, both eVCPs have a conserved intron/exon organization spanning 14 kb, which is also conserved to their mammalian counterparts. Although this finding strongly suggests VCPs have a common ancestral origin, phylogenetic analysis predicts that eVCP-2 may be distinct. An investigation by reverse transcription-polymerase chain reaction (RT-PCR) revealed that, whilst evcp-1 was ubiquitously expressed during all developmental stages, evcp-2 was specifically expressed in the anterior segments of sexually mature earthworms. In situ hybridization clearly demonstrated that evcp-2 is expressed in the seminal vesicles, the location of spermatogenesis, and more precisely within the cytophores surrounded by secondary spermatocytes or spermatids. Taken together, this evidence leads to the notion that eVCP-2 is a likely component involved in the final modulation of spermatogenesis.

Adenosine Triphosphatases↗

PubMed2003

Keratinocyte growth inhibition by high-dose epidermal growth factor is mediated by transforming growth factor beta autoinduction: a negative feedback mechanism for keratinocyte growth.

The epidermal growth factor receptor and its ligands initiate a major signaling pathway that regulates keratinocyte growth in an autocrine manner. It is well known that high doses of epidermal growth factor receptor ligands inhibit keratinocyte growth. Recently, signal transducers and activators of transcription 1-dependent p21Waf1/Cip1 induction were reported to be involved in high-dose epidermal growth factor-dependent cell growth arrest in the A431 squamous cell carcinoma cell line; however, transfection of dominant-negative signal transducers and activators of transcription 1 adenovirus vector did not block epidermal growth factor-induced growth inhibition in normal human keratinocytes. As transforming growth factor beta is a potent inhibitor of keratinocyte proliferation, we hypothesized that transforming growth factor beta contributes to epidermal growth factor-mediated keratinocyte growth inhibition. Epidermal growth factor concentrations of 10 ng per ml enhanced transforming growth factor beta1 mRNA expression from 3 to 6 h poststimulation. Enzyme-linked immunosorbent assay analysis detected 150 pg per ml of transforming growth factor beta1 in the culture medium of keratinocytes incubated with 10 and 100 ng per ml epidermal growth factor, whereas 0.1 and 1.0 ng per ml epidermal growth factor slightly enhance transforming growth factor beta1 production. Epidermal growth factor (100 ng per ml) upregulated luciferase activity of p3TP-lux, which contains three tandem transforming growth factor beta-Smad signaling responsive elements, 6-fold compared with unstimulated cells. The epidermal growth factor-dependent induction of p3TP-lux luciferase activity was disrupted by transfection of the dominant negative form of transforming growth factor beta type I receptor adenovirus vector (AxdnALK5), which suggests that epidermal growth factor-induced transforming growth factor beta acts in an autocrine manner in keratinocytes. Moreover, transfection of AxdnALK5 completely blocked the growth inhibition induced by 100 ng per ml of epidermal growth factor in normal keratinocytes. These data demonstrate that an autocrine transforming growth factor beta1-ALK5 pathway is a negative feedback mechanism for epidermal growth factor-induced normal human keratinocyte growth.

Activin Receptors, Type I↗