title: Functional cloning of SPIN-2, a nuclear anti-apoptotic protein with roles in cell cycle progression.
abstract: The balance between hematopoietic cell viability and apoptosis is regulated by exogenous growth factors, however, the molecular mechanisms by which these trophic factors exert their effects remain obscure. A functional retroviral cDNA library-based screen was employed to identify genes that prevent growth factor withdrawal-mediated apoptosis in the myeloid progenitor cell 32Dcl3. This approach identified three classes of genes: those with known roles in apoptosis (bcl-X(L) and ornithine decarboxylase); genes previously identified but not linked directly to apoptotic signaling (O-linked N-acetylglucosamine transferase); and a previously uncharacterized gene we termed SPIN-2. In 32Dcl3 cells, expression of exogenous SPIN-2 provides 25% protection from apoptosis following growth factor withdrawal compared to controls which show approximately 1-2% survival. SPIN-2 overexpression slows cell growth rates and increases the percentage of cells in G(2)/M (32% vs control cells at 12%). Immunolocalization studies indicate that myc-epitope tagged SPIN-2 proteins, which retain their anti-apoptotic function, reside in the nucleus, whereas a C-terminal deletion mutant that loses its anti-apoptotic activity is located in the cytoplasm. These studies suggest that SPIN-2 is a novel nuclear protein that functions to regulate cell cycle progression and this activity is related to the inhibition of apoptosis following the removal of essential growth factors.
authors.affiliation: Department of Pharmacology and Therapeutics, University of Florida, College of Medicine, Gainesville, FL 32610-0267, USA.
authors.forename: B S
authors.initials: BS
authors.lastname: Fletcher
authors.forename: C
authors.initials: C
authors.lastname: Dragstedt
authors.forename: L
authors.initials: L
authors.lastname: Notterpek
authors.forename: G P
authors.initials: GP
authors.lastname: Nolan
mesh_terms: D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D002453:Cell Cycle / Q000235:genetics*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D002460:Cell Line / Q000166:cytology / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D020869:Gene Expression Profiling; D015723:Gene Library; D005822:Genetic Vectors / Q000235:genetics; D018922:HL-60 Cells / Q000737:chemistry; D006801:Humans; D007377:Interleukin-3 / Q000494:pharmacology; D019169:Jurkat Cells / Q000166:cytology; D051379:Mice; D008969:Molecular Sequence Data; D022423:Myeloid Cells / Q000166:cytology / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics; D012334:RNA, Neoplasm / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000502:physiology; D012190:Retroviridae / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D014960:X Chromosome / Q000235:genetics
chemical_list: D018797:Cell Cycle Proteins; D018076:DNA, Complementary; D007377:Interleukin-3; D009687:Nuclear Proteins; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D011993:Recombinant Fusion Proteins; C463239:SPIN2A protein, human