Biomedical subjects

Reiko Mabuchi

Publications and source records attributed to Reiko Mabuchi.

2 recordsLinked to original sources

PubMed2005

Mapping of the critical region of mitogene-inducible gene-6 for NF-kappaB activation.

Mitogene-inducible gene-6 (Mig-6) is involved in the intracellular signaling pathway as an adaptor molecule. Mig-6 expression is rapidly induced upon various kinds of mitogenic and stressful stimulations. We previously demonstrated that Mig-6 expression is induced by activated Ki-ras in human colon cancer cells and the limited proteolytic processed NH(2)-terminal region containing the Cdc42/Rac interaction and binding (CRIB) domain of Mig-6 is bound to IkappaBalpha, resulting in NF-kappaB activation. In this study, we tried to determine the critical region of Mig-6 for regulating NF-kappaB activation by using various kinds of deletion-constructs of Mig-6. The CRIB domain-deleted Mig-6 fragment (residues 68 to 462) did not show significant NF-kappaB activation. Furthermore, NH(2)-terminal 148, 158 and 180 amino acid regions of Mig-6 did not show NF-kappaB activation. On the other hand, the NH(2)-terminal 264 amino acid region of Mig-6 did show NF-kappaB activation to a similar extent of the full length of Mig-6. Interestingly, the full length and NH(2)-terminal 264 amino acid region of Mig-6 produced two kinds of cleaved NH(2)-terminal fragments, N1 and N2 with an approximate molecular size of 5 and 7 kDa, respectively. The NH(2)-terminal 148 and 158 amino acid regions of Mig-6 did not produce N1 or N2 fragments, while the NH(2)-terminal 180 amino acid region of Mig-6 only produced the N1 fragment. Furthermore, the N2 fragment was bound with IkappaBalpha, but the N1 fragment was not. These results together suggested that the NH(2)-terminal 264 amino acid region is critical for NF-kappaB activation and proper limited proteolytic processing of Mig-6.

Adaptor Proteins, Signal Transducing↗

PubMed2003

Laminin expression patterns in human ureteral tissue.

PURPOSE: Laminins are extracellular matrix proteins that are involved in various cellular functions, including adhesion, proliferation and differentiation. In this study we examined the expression patterns of the laminin chains in human ureteral tissue in vitro and in vivo. MATERIALS AND METHODS: We screened the expression of laminin chains at the mRNA level and determined the major laminins expressed in epithelial and stromal cells of human ureteral tissue by reverse transcriptase-polymerase chain reaction and Western blot analysis. We also examined their expression in vivo by immunofluorescence study. RESULTS: Reverse transcriptase-polymerase chain reaction analysis revealed that urothelial cells in vitro expressed laminins alpha1, alpha3, alpha5, beta1, beta2, beta3, gamma1 and gamma2, while stromal cells expressed alpha1, alpha2, alpha4, alpha5, beta1, beta2 and gamma1. Western blot analysis under reduced conditions confirmed that urothelial cells expressed laminin alpha3 and alpha5, while stromal cells strongly expressed alpha4 and alpha2. Immunofluorescence labeling with antilaminin alpha chain antibodies in human ureteral tissues confirmed that laminin alpha2, alpha3 and alpha5 chains were strongly expressed in the basement membrane of the urothelium, while alpha4 was expressed predominantly in smooth muscle cells. CONCLUSIONS: The most prominent laminin of urothelial cells was laminin 5 (alpha3beta3gamma2), whereas in stromal cells we noted laminins 8/9 (alpha4beta1/2gamma1). Laminin alpha5 showed the widest distribution pattern in vivo. Our data may be useful for understanding the mechanism involved not only in cell growth and differentiation, but also in cancer invasion in the urinary tract.

Basement Membrane↗