期刊
BONE
卷 34, 期 1, 页码 100-111出版社
ELSEVIER SCIENCE INC
DOI: 10.1016/j.bone.2003.09.007
关键词
osteoblast; differentiation; estrogen receptor alpha; PKC; c-Src
资金
- EUNICE KENNEDY SHRIVER NATIONAL INSTITUTE OF CHILD HEALTH &HUMAN DEVELOPMENT [R01HD036015] Funding Source: NIH RePORTER
- NATIONAL INSTITUTE OF ENVIRONMENTAL HEALTH SCIENCES [Z01ES070065] Funding Source: NIH RePORTER
- NICHD NIH HHS [HD36015] Funding Source: Medline
- Telethon [E.0831] Funding Source: Medline
In cultured osteoblasts, protein kinase C (PKC) activity increases and estrogen receptor alpha (ERalpha) binding capacity decreases upon confluence. We investigated potential interactions between ERalpha and PKC isoforms and their confluence-induced modulations in clonal ROS. SMER#14 cells and primary osteoblasts. In sub-confluent ROS.SMER#14 cells, which express an exogenous plus small amounts of the endogenous ERalpha gene, the receptor appeared as two main bands of approximate to 66 and approximate to 46 kDa. In over-confluent, more differentiated cells, the cytosolic approximate to 66 kDa ERa appeared decreased and the approximate to 46 kDa variant increased. Enhanced expression and/or membrane translocation of PKCalpha and PKCepsilon, but not PKCzeta, was evidenced at over-confluence, along with transient increases in expression and kinase activity of c-Src, accompanied by membrane translocation of the kinase-activated enzyme. In contrast, negligible membrane translocation of PKCa and/or activated c-Src was observed in parental ROS 17/2.8 cells, which express low levels of full-length ERalpha. PKCa from over-confluent cells phosphorylated p60(c-Src) in vitro, suggesting functional interaction between the two kinases. ERalpha co-immunoprecipitated c-Src and PKCalpha, mostly in its cleaved form (PKMalpha). An analogous interaction was observed in primary osteoblasts. However, in these cells, much more PKCalpha/ PKMa was ERalpha-co-immunoprecipitated at over-confluence, a condition in which the shorter, approximate to 46 kDa ERalpha variant is increased. This interaction was enhanced by estradiol treatment or PKC down-regulation, but was unaffected by c-Src inhibition. These data highlight direct PKCalpha-c-Src-ERalpha interactions, which may be crucial in the modulation of estrogen responsiveness and the differentiation process in osteoblasts. (C) 2003 Published by Elsevier Inc.
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