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ABSTRACT: Previous studies have indicated that noggin exerts its neural inducing effect by binding and antagonizing bone morphogenetic protein 4 (BMP4). In order to further clarify the relationship between the structure and the function of noggin, and elucidate the possible mechanism responsible for noggin-BMP4 interaction, we generated three noggin mutants, C168S, C174S and C197S, by using a site-directed mutagenesis method. Ectopic expression of wild-type (WT) noggin, C174S or C197S, in Xenopus animal caps (ACs) by mRNA injection converted the explants (prospective ectoderm) into neural tissue, as indicated by the neural-like morphology and expression of the neural cell adhesion molecule (NCAM) in the ACs. In contrast, ACs expressing C168S suffered an epidermal fate similar to the control caps. Similarly, among the three mutants, only C168S lost the dorsalizing function. These studies highlight the critical role played by Cys168 in noggin's biological activities. It probably participates in the formation of an intermolecular disulfide bridge.
Acta Biochimica et Biophysica Sinica 04/2005; 37(3):181-5. · 1.38 Impact Factor
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ABSTRACT: The GATA-1 of Xenopus (xGATA-1), which has two subtypes xGATA-1a and xGATA-1b, is a necessary factor for erythroid differentiation and maturation as similar as that of other GATA-1s. Although both xGATa-1a and xGATA-1b are able to stimulate erythropoiesis, only xGATA-1b is capable of inhibiting neurogenesis in Xenopus embryos. Compared between their structures, xGATA-1a and xGATA-1b are very similar in nucleotide and amino acids composition, but not identical. Therefore, it is responsible for studying the role of the diverse codons between the two genes, so the desired mutations: S(168), H(169) double deletion and point mutation of T(304)-->A, T(359)-->A, were introduced into xGATA-1b gene through site-directed mutagenesis. Then, mRNA from each mutant as well as wtxGATA-1b was co-injected with DN-BR mRNA or separately injected into Xenopus stage 2 embryos, and the role of mutants in erythropoiesis and neurogenesis was analyzed by using animal cap culture system. The results showed that the neural-inhibiting activity of xGATA-1b, but not hematopoiesis-inducing activity, was aborted because of deletion of Ser(168) and His(169) or point mutation of T(359)-->A. So it is demonstrated for the first time that Ser(168) and His(169) or Thr(359)in xGATA-1b may be one of the structural basis for explanting the different function between xGATA-1b and xGATA-1a.
Sheng wu hua xue yu sheng wu wu li xue bao Acta biochimica et biophysica Sinica 01/2004; 35(12):1105-10.
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ABSTRACT: Mouse Atlas(TM) cDNA Expression Arrays were used to analyze cellular gene expression profiles of human complement receptor type II gene (hCR2)-transfected mouse cells before and after EBV infection and TPA treatment, followed by screening differentially expressed genes with Eagle Eye II Image Analysis System. Results indicated that differentially expressed gene prifiles of EBV and TPA treated, hCR2-transfected mouse cells was preliminarily established. This study laid the basis for further research in relerant fields.
Sheng wu hua xue yu sheng wu wu li xue bao Acta biochimica et biophysica Sinica 02/2001; 33(1):105-111.
