ABSTRACT
Using a polymerase chain reaction-mediated cloning procedure, we have identified a novel member, termed ANA (from Abundant in Neuroepithelium Area), of Tob/BTG1 family of antiproliferative genes. Molecular cloning and analysis of cDNAs revealed that the human and mouse ANA encoded a protein of 252 amino acids. The amino-terminal half of ANA was homologous to the previously characterized antiproliferative gene products, BTG1, PC3/TIS21/BTG2, and Tob. The human ANA gene was localized at chromosome 21q11.2-q21.1. ANA was expressed in a variety of tissues and cell lines, its expression being high in the ovary, testis, prostate, thymus, and lung. Further analysis revealed that ANA expression was high in the ventricular zone of the developing central nervous system. Finally, overexpression of ANA impaired serum-induced cell cycle progression from the G0/G1 to S phase. In conclusion, ANA is a fourth member of the Tob/BTG1 family that might play roles in neurogenesis in the central nervous system.
Subject(s)
Drosophila Proteins , Glycoproteins/metabolism , Intracellular Signaling Peptides and Proteins , Tumor Suppressor Proteins , Amino Acid Sequence , Animals , Base Sequence , Carrier Proteins/genetics , Cell Cycle , Cell Division/drug effects , Chromosome Mapping , Chromosomes, Human, Pair 21 , Cloning, Molecular , Humans , Mice , Molecular Sequence Data , Neoplasm Proteins/genetics , Polymerase Chain Reaction , Tissue DistributionABSTRACT
Human cDNAs encoding a novel member of Tob/BTG1 anti-proliferative family proteins were cloned. The putative protein product termed Tob2 consisted of 344 amino acids with high similarity to the Tob protein. The tob2 mRNA was 4.1 kb long and was ubiquitously expressed in human adult tissues, as was revealed by Northern blot hybridization. However, further in situ hybridization analysis showed a characteristic expression of the tob2 mRNA in oocytes, suggesting a unique role of Tob2 in oogenesis. Like the Tob protein, Tob2 inhibited cell cycle progression from the G0/G1 to S phases. Intriguingly, the amino-terminal half of Tob2 as well as that of Tob was associated with a human homologue of yeast Caf1, a component of the CCR4 transcription factor complex. Moreover, Caf1 was associated with cyclin dependent kinases. These data suggested that both Tob and Tob2 were involved in cell cycle regulation through their interaction with Caf1. Finally, the tob2 gene was mapped to human chromosome 22q13.1-q13.31.
Subject(s)
CDC2-CDC28 Kinases , Cell Cycle Proteins/genetics , Cell Cycle Proteins/metabolism , Cyclin-Dependent Kinases/metabolism , Intracellular Signaling Peptides and Proteins , Proteins , Proto-Oncogene Proteins , Transcription Factors/metabolism , Tumor Suppressor Proteins , 3T3 Cells/cytology , 3T3 Cells/metabolism , Amino Acid Sequence , Animals , Base Sequence , Carrier Proteins/metabolism , Cell Line , Cloning, Molecular , Cyclin-Dependent Kinase 2 , Cyclin-Dependent Kinase 4 , Exoribonucleases , G1 Phase/genetics , Gene Expression Profiling , Humans , Male , Mice , Molecular Sequence Data , Neoplasm Proteins/genetics , Protein Serine-Threonine Kinases/metabolism , Rabbits , Repressor Proteins , Ribonucleases , Sequence Homology, Amino Acid , Subcellular Fractions , Transcription Factors/geneticsABSTRACT
Human Tob2 is a member of the Tob/BTG1 anti-proliferative family of proteins. Here, we report the molecular cloning and characterization of the mouse tob2 gene. The tob2 gene contains an open reading frame of 345 amino acids with an 89% identity to its human counterparts. The coding region of mouse tob2 is not interrupted by introns. The tob2 transcript is 4.2kb long, the size being similar to that of the human tob2 transcript, and detected ubiquitously in various tissues of adult mice. In addition, in situ hybridization shows that tob2 is ubiquitously expressed in embryo, the level of expression being especially high in skeletal muscle. Collectively, Tob2 is suggested to play roles both during embryogenesis and in adults.
Subject(s)
Cell Cycle Proteins/genetics , Genes/genetics , 3T3 Cells , Amino Acid Sequence , Animals , Base Sequence , Blotting, Northern , Blotting, Southern , Cell Line , Cloning, Molecular , DNA/chemistry , DNA/genetics , DNA/isolation & purification , Gene Expression , Humans , In Situ Hybridization , Male , Mice , Mice, Inbred Strains , Molecular Sequence Data , RNA, Messenger/genetics , RNA, Messenger/metabolism , Sequence Alignment , Sequence Analysis, DNA , Sequence Homology, Amino Acid , Tissue DistributionABSTRACT
Inflammatory cytokines such as tumor necrosis factor alpha (TNF alpha), interferon gamma (IFN gamma) and interleukin-1 beta (IL-1 beta) play important roles in the mechanisms of hepatitis. The effects of these cytokines on the expression of vascular cell adhesion molecule-1 (VCAM-1) in hepatocytes were examined. TNF alpha and IL-1 beta but not IFN gamma or IL-6 induced VCAM-1 expression on primary cultured murine hepatocytes in a dose- and a time-dependent fashion. TNF alpha is significantly more effective than IL-1 beta on the induction of VCAM-1 expression. The results of RT-PCR demonstrate that these cytokines regulate VCAM-1 expression at mRNA level. These results suggest that TNF alpha and IL-1 beta participate in the pathogenesis of hepatitis via induction of VCAM-1 molecules on hepatocytes.
Subject(s)
Cell Adhesion Molecules/biosynthesis , Interferon-gamma/pharmacology , Interleukin-1/pharmacology , Liver/metabolism , Tumor Necrosis Factor-alpha/pharmacology , Animals , Base Sequence , Cell Adhesion Molecules/genetics , Cells, Cultured , DNA Primers , Liver/cytology , Mice , Molecular Sequence Data , Polymerase Chain Reaction , RNA, Messenger/genetics , RNA, Messenger/metabolism , Vascular Cell Adhesion Molecule-1ABSTRACT
Bone morphogenetic protein (BMP) controls osteoblast proliferation and differentiation through Smad proteins. Here we show that Tob, a member of the emerging family of antiproliferative proteins, is a negative regulator of BMP/Smad signaling in osteoblasts. Mice carrying a targeted deletion of the tob gene have a greater bone mass resulting from increased numbers of osteoblasts. Orthotopic bone formation in response to BMP2 is elevated in tob-deficient mice. Overproduction of Tob represses BMP2-induced, Smad-mediated transcriptional activation. Finally, Tob associates with receptor-regulated Smads (Smad1, 5, and 8) and colocalizes with these Smads in the nuclear bodies upon BMP2 stimulation. The results indicate that Tob negatively regulates osteoblast proliferation and differentiation by suppressing the activity of the receptor-regulated Smad proteins.