Msx homeobox gene family and craniofacial development

Vertebrate Msx genes are unlinked,homeobox-containing genes that bear homology to the Drosophila muscle segment homeobox gene.These genes are expressed at multiple sites of tissue-tissue interactions during vertebrate embryonic development.Inductive interactions mediated by the Msx genes are essential for normal craniofacial,limb and ectodermal organ morphogenesis,and are also essential to survival in mice,as manifested by the phenotypic abnormalities shown in knockout mice and in humans.This review summarizes studies on the expression,regulation,and functional analysis of Msx genes that bear relevance to craniofacial development in humans and mice.

Making a tooth:growth factors,transcription factors,and stem cells

Mammalian tooth development is largely dependent on sequential and reciprocal epithelial-mesenchymal interactions. These processes involve a series of inductive and permissive interactions that result in the determination, differentiation, and organization of odontogenic tissues. Multiple signaling molecules, including BMPs, FGFs, Shh, and Wnt proteins, have been implicated in mediating these tissue interactions. Transcription factors participate in epithelial-mesenchymal interactions via linking the signaling loops between tissue layers by responding to inductive signals and regulating the expression of other signaling molecules. Adult stem cells are highly plastic and multipotent. These cells including dental pulp stem cells and bone marrow stromal cells could be reprogrammed into odontogenic fate and participated in tooth formation. Recent progress in the studies of molecular basis of tooth development, adult stem cell biology, and regene- ration will provide fundamental knowledge for the realization of human tooth regeneration in the near future.

Construction of human liver cancer vascular endothelium cDNA expression library and screening of the endothelium-associated antigen genes

AIM: To gain tumor endothelium associated antigen genes from human liver cancer vascular endothelial cells (HLCVECs)cDNA expression library, so as to find some new possible targets for the diagnosis and therapy of liver tumor.METHODS: HLCVECs were isolated and purified from a fresh hepatocellular carcinoma tissue sample, and were cultured and proliferated in vitro. A cDNA expression library was constructed with the mRNA extracted from HLCVECs.Anti-sera were prepared from immunized BALB/c mice through subcutaneous injection with high dose of fixed HLCVECs, and were then tested for their specificity against HLCVECs and angiogenic effects in vitro, such as inhibiting proliferation and inducing apoptosis of tumor endothelial cells, using immunocytochemistry, immunofluorescence,cell cycle analysis and M-I-l- assays, etc. The identified xenogeneic sera from immunized mice were employed to screen the library of HLCVECs by modified serological analyses of recombinant cDNA expression libraries (SEREX).The positive clones were sequenced and analyzed by bioinformatics.RESULTS: The primary cDNA library consisted of 2×10^6 recombinants. Thirty-six positive clones were obtained from 6× 10^5 independent dones by immunoscreening. Bio-informatics analysis of cDNA sequences indicated that 36 positive clones represented 18 different genes. Among them, 3 were new genes previously unreported, 2 of which were hypothetical genes. The other 15 were already known ones. Series analysis of gene expression (SAGE) database showed that ERP70,GRP58, GAPDH, SSB, $100A6, BMP-6, DVS27, HSP70 and NAC alpha in these genes were associated with endothelium and angiogenesis, but their effects on HLCVECs were still unclear. GAPDH, $100A6, BMP-6 and hsp70 were identified by SEREX in other tumor cDNA expression libraries.CONCLUSION: By screening of HLCVECs cDNA expression library using sera from immunized mice with HLCVECs,the functional genes associated with tumor endothelium or angiogenesis were identified. The modified SEREX,xenogeneic functional serum screening, was demonstrated to be effective for isolation and identification of antigen genes of tumor endothelium, and also for other tumor cell antigen genes. These antigen genes obtained in this study could be a valuable resource for basic and clinical studies of tumor angiogenesis, thus facilitating the development of anti-angiogenesis targeting therapy of tumors.