Cell cycle arrest and apoptosis by expression of a novel TPIP (TPIP-C2) cDNA encoding a C2-domain in HEK-293 cells.
The human TPIP (TPTE and PTEN homologous Inositol lipid Phosphatase) belongs to the PTEN (Phosphatase and TENsin homologue deleted on chromosome 10) family of dual-specific phosphatases and is expressed from the human chromosome 13 as multiple splice-variants, e.g., TPIPα, β, γ mRNAs. PTEN is a well characterized tumor suppressor, which controls survival, adhesion, motility and migration of mammalian cells, its C2-domain plays crucial role in controlling these functions. However, role of isolated C2-domain protein in regulation of cell proliferation and apoptosis is not reported. We report sequence analysis and function of a novel human TPIP (TPIP-C2) cDNA encoding a 193 amino acid C2-domain in cell proliferation and apoptosis regulation. In silico analysis and homology modelling revealed that the C2-domain of TPIP-C2 is similar to that of PTEN but with short disorder sequences overlapping or adjacent to the post-translational modification sites. Overexpression of TPIP-C2 cDNA in human embryonic kidney (HEK-293) cells caused cell cycle arrest, inhibition of cell proliferation and induced apoptosis in an activated caspase 3 and PARP-dependent manner in comparison to overexpression of the full length human PTEN cDNA. TPIP-C2 overexpressed cells also showed S-phase cell cycle arrest. We suggest that C2-domain of TPIP-C2 may act as a dominant negative effector, which may bind to and arrest the cell proliferation signalling complex and isolated TPIP-C2-domain-like proteins expressed in mammalian cells/tissues may play important role in regulation of cell proliferation and apoptosis. The TPIP-C2 cDNA may be exploited for inducing cell cycle-inhibition and apoptosis in human cancer cells and tissues.
Molecular Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
Rasmi Rekha
RR
Mishra
Jitendra Kumar
JK
Chaudhary
Pramod C
PC
Rath
D000595:Amino Acid Sequence; D017209:Apoptosis / Q000235:genetics*; D001483:Base Sequence; D059447:Cell Cycle Checkpoints / Q000235:genetics*; D002460:Cell Line; D049109:Cell Proliferation; D002470:Cell Survival; D054637:Dual-Specificity Phosphatases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D051059:PTEN Phosphohydrolase / Q000235:genetics* / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics; D011499:Protein Processing, Post-Translational; D017433:Protein Structure, Secondary; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
D008565:Membrane Proteins; D020033:Protein Isoforms; D054637:Dual-Specificity Phosphatases; C446603:TPTE protein, human; D051059:PTEN Phosphohydrolase; C576347:TPTE2 protein, human