Cytoskeleton reorganization and FAK phosphorylation are involved in lanthanum (III)-promoted proliferation and differentiation in rat osteoblasts

The effect of lanthanum ion (La(3+)) on osteoblast function and cytoskeleton is assessed in vitro. Osteoblasts were isolated from Sprague Dawley fetal neonatal rats. Cell proliferation and gene expression levels of cbfa-1, alkaline phosphatase (ALP), osteocalcin (OC), bone sialoprotein (BSP) and osteopontin (OPN) were examined by cell counting and RT-PCR. Cytoskeleton F-actin was stained with rhodamine-conjugated phalloidin and was visualized by a confocal microscope. As the results, 10(-8)-10(-4) M La(3+)- induced osteoblast proliferation on day 2. Data from the RT-PCR assay revealed that 10(-6) M La(3+) up-regulated the expression levels of ALP, BSP, and cbfa-1 on day 4, while it enhanced the expressions of OC and OP N on day 21. The F-actin cytoskeletonwas strengthened and reorganized under the exposure of La(3+). In addition, the phosphorylation of focal adhesion kinase (FAK) was significantly promoted in 24 h evaluated by Western blot analysis. These findings indicate that La(3+) promotes osteoblast activity through the phosphorylation of FAK and reorganization of the cytoskeleton. (C) 2008 National Natural Science Foundation of China and Chinese Academy of Sciences. Published by Elsevier Limited and Science in China Press. All rights reserved.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000263557200006&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Materials Science, MultidisciplinaryMultidisciplinary SciencesSCI(E)9ARTICLE3331-3351