Wnt signaling plays an important role in embryogenesis and tumorgenesis. Although the mechanism about how Wnts transduce their signaling from receptor frizzled (Fz) to cytosol has not been understood, dishevelled (Dvl...Wnt signaling plays an important role in embryogenesis and tumorgenesis. Although the mechanism about how Wnts transduce their signaling from receptor frizzled (Fz) to cytosol has not been understood, dishevelled (Dvl) protein was considered as the intersection of Wnt signal traffic. In this study, we characterized the function of three domains (DIX,PDZ and DEP) of Dvl-1 in canonical Wnt signal transduction and Dvl-1 membrane translocation. It was found both DIX and DEP domain were sufficient to block Wnt-3a-induced LEF-1 transcriptional activity and free cytosol β-catenin accumulation; whereas PDZ domain and a functional mutant form of DEP domain (DEP-KM) had no effect on canonical Wnt signaling. In addition, when cotransfected with Fz-7, DEP domain, but not DIX, PDZ or DEP-KM, translocated and co-localized with Fz-7 to the plasma membrane, which was similar to Dvl-1. Furthermore, it was DEP domain that could block Fz-7-induced membrane translocation of Dvl- 1 via a possible competitive mechanism. These results strongly suggest that DEP domain is responsible for the membrane translocation of Dvl-1 protein upon Wnt signal stimulation.展开更多
Chemotaxis is a fascinating biological process, through which a cell migrates along a shallow chemoattractant gradient that is less than 5% difference between the anterior and posterior of the cell. Chemotaxis is comp...Chemotaxis is a fascinating biological process, through which a cell migrates along a shallow chemoattractant gradient that is less than 5% difference between the anterior and posterior of the cell. Chemotaxis is composed of two independent, but interrelated processes-motility and directionality, both of which are regulated by extracellular stimuli, chemoattractants. In this mini-review, recent progresses in the understanding of the regulation of leukocyte chemotaxis by chemoattractant signaling are reviewed.展开更多
Myxococcus xanthus provides an excellent model organism for studying the mechanism of multicellular morphogenesis. The mRNA for FruA, a transcription factor essential for the development of M. xanthus, contains a very...Myxococcus xanthus provides an excellent model organism for studying the mechanism of multicellular morphogenesis. The mRNA for FruA, a transcription factor essential for the development of M. xanthus, contains a very long 5′-UTR consisting of 235 nucleotides. Using lacZ as a reporter gene, two fruA-lacZ translational fusions retaining or lacking the fruA 5′-UTR were constructed and separately integrated at phage Mx8 attachment site (attB) in M. xanthus chromosome. Deletion in 5′-UTR between nucleotides from +4 to +220 abolished fruA-lacZ expression during develop- ment, indicating that the 5′-UTR is essential for the induction of fruA. Prediction of the RNA secondary structure of 5′-UTR shows that this region could form an extremely sta- ble three-helix junction structure, which might be a binding site for a regulatory protein or contain a cis-acting element(s) to control fruA expression. Thus, the 5′-UTR of fruA mRNA positively regulates the expression of its own gene.展开更多
文摘Wnt signaling plays an important role in embryogenesis and tumorgenesis. Although the mechanism about how Wnts transduce their signaling from receptor frizzled (Fz) to cytosol has not been understood, dishevelled (Dvl) protein was considered as the intersection of Wnt signal traffic. In this study, we characterized the function of three domains (DIX,PDZ and DEP) of Dvl-1 in canonical Wnt signal transduction and Dvl-1 membrane translocation. It was found both DIX and DEP domain were sufficient to block Wnt-3a-induced LEF-1 transcriptional activity and free cytosol β-catenin accumulation; whereas PDZ domain and a functional mutant form of DEP domain (DEP-KM) had no effect on canonical Wnt signaling. In addition, when cotransfected with Fz-7, DEP domain, but not DIX, PDZ or DEP-KM, translocated and co-localized with Fz-7 to the plasma membrane, which was similar to Dvl-1. Furthermore, it was DEP domain that could block Fz-7-induced membrane translocation of Dvl- 1 via a possible competitive mechanism. These results strongly suggest that DEP domain is responsible for the membrane translocation of Dvl-1 protein upon Wnt signal stimulation.
文摘Chemotaxis is a fascinating biological process, through which a cell migrates along a shallow chemoattractant gradient that is less than 5% difference between the anterior and posterior of the cell. Chemotaxis is composed of two independent, but interrelated processes-motility and directionality, both of which are regulated by extracellular stimuli, chemoattractants. In this mini-review, recent progresses in the understanding of the regulation of leukocyte chemotaxis by chemoattractant signaling are reviewed.
文摘Myxococcus xanthus provides an excellent model organism for studying the mechanism of multicellular morphogenesis. The mRNA for FruA, a transcription factor essential for the development of M. xanthus, contains a very long 5′-UTR consisting of 235 nucleotides. Using lacZ as a reporter gene, two fruA-lacZ translational fusions retaining or lacking the fruA 5′-UTR were constructed and separately integrated at phage Mx8 attachment site (attB) in M. xanthus chromosome. Deletion in 5′-UTR between nucleotides from +4 to +220 abolished fruA-lacZ expression during develop- ment, indicating that the 5′-UTR is essential for the induction of fruA. Prediction of the RNA secondary structure of 5′-UTR shows that this region could form an extremely sta- ble three-helix junction structure, which might be a binding site for a regulatory protein or contain a cis-acting element(s) to control fruA expression. Thus, the 5′-UTR of fruA mRNA positively regulates the expression of its own gene.
