Expression of galectin-3 modulates T-cell growth and apoptosis.
Galectin-3 is a member (if a large family of beta-galactoside-binding animal lectins. It has been shown that the expression of galectin-3 is upregulated in proliferating cells, suggesting a possible role for this lectin in regulation of cell growth. Previously, we have shown that T cells infected with human T-cell leukemia virus type I express high levels of galectin-3, in contrast to uninfected cells, which do not express detectable amounts of this protein. In this study, we examined growth properties of human leukemia T cells transfected with galectin-3 cDNA, and thus constitutively overexpressing this lectin. Transfectants expressing galectin-3 displayed higher growth rates than control transfectants, which do not express this lectin. Furthermore, galectin-3 expression in these cells confers resistance to apoptosis induced by anti-Fas antibody and staurosporine. Galectin-3 was found to have significant sequence similarity with Bcl-2, a well-characterized suppressor of apoptosis. In particular, the lectin contains the NWGR motif that is highly conserved among members of the Bcl-2 family and shown to be critical for the apoptosis-suppressing activity. We further demonstrated that galectin-3 interacts with Bc1-2 in a lactose-inhibitable manner. We conclude that galectin-3 is a regulator of cell growth and apoptosis and it may function through a cell death inhibition pathway that involves Bcl-2.
Yang
R Y
RY
Department of Molecular and Experimental Medicine, Scripps Research Institute, La Jolla, CA 92037, USA.
Hsu
D K
DK
Liu
F T
FT
D000595:Amino Acid Sequence; D000943:Antigens, Differentiation / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D017209:Apoptosis / Q000235:genetics*; D001483:Base Sequence; D001769:Blood; D002455:Cell Division / Q000235:genetics*; D002460:Cell Line; D017931:DNA Primers; D037502:Galectin 3; D006801:Humans; D037102:Lectins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2; D017386:Sequence Homology, Amino Acid; D013601:T-Lymphocytes / Q000166:cytology*; D014162:Transfection
D000943:Antigens, Differentiation; D017931:DNA Primers; D037502:Galectin 3; D037102:Lectins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2