CCAAT/enhancer-binding protein-beta participates in insulin-responsive expression of the factor VII gene

Expression of the human coagulation factor VII (FVII) gene by hepatoma cells was modulated in concert with levels of glucose and insulin in the culture medium. In low glucose medium without insulin, amounts of both FVII mRNA and secreted FVII protein were coordinately increased; in the presence of glucose with insulin, both were decreased. Analysis of the FVII promoter showed that these effects could be reproduced in a reporter-gene system, and a small promoter element immediately upstream of the translation start site of the gene, which mediated these effects, was identified. Mutation of this element largely abrogated the glucose/insulin-responsive change in expression of the reporter gene. Several members of the CCAAT/enhancer-binding protein family were found to be capable of binding the identified sequence element but not the mutated element. The expression of a FVII minigene directed by a segment of the native FVII promoter responded to co-expressed activating and inhibiting forms of CCAAT/enhancer-binding protein beta.     

Sesquiterpenoids from Homalomena occulta affect osteoblast proliferation, differentiation and mineralization in vitro

Chemical investigation of rhizomes of Homalomena occulta (Lours) resulted in isolation and identification of two sesquiterpenoids (6,7), and one daucane ester 8, together with five known sesquiterpenoids, oplodiol, oplopanone, homalomenol C, bullatantriol, and 1beta,4beta,7alpha-trihydroxyeudesmane. Their structures were elucidated using 1D and 2D NMR spectroscopic and X-ray analyses. The chloroform extract of this plant and compounds 1-7 were tested in vitro for their activities in stimulating osteoblast (OB) proliferation, differentiation and mineralization. Compounds 1-4 had a stimulative effect on significantly proliferation and differentiation of culture osteoblasts, while the chloroform extract and 1 significantly stimulated mineralization of cultured osteoblasts in vitro.     

A proteomic study on human osteoblastic cells proliferation and differentiation

Changes in expression profiles for 17 proteins were ascertained in human mature osteoblasts compared to pre-osteoblasts (differentiation markers). A differential approach was used to highlight proteomic changes between human osteosarcoma cells and mature osteoblasts, showing a relative over-expression of 8 proteins (proliferation and tumor indicators), as well as under-expression of proteins also found down-regulated in pre-osteoblasts (specific markers of osteoblast differentiation). Our findings confirmed the differences between cell lines and primary human cell cultures and suggested caution on the use of osteosarcoma to study anti-osteoporotic drugs in humans.