title: p53 accumulation, defective cell proliferation, and early embryonic lethality in mice lacking tsg101.
abstract: Functional inactivation of the tumor susceptibility gene tsg101 in NIH 3T3 fibroblasts results in cellular transformation and the ability to form metastatic tumors in nude mice. The N-terminal region of tsg101 protein is structurally similar to the catalytic domain of ubiquitin-conjugating enzymes, suggesting a potential role of tsg101 in ubiquitin-mediated protein degradation. The C-terminal domain of TSG101 can function as a repressor of transcription. To investigate the physiological function of tsg101, we generated a null mutation of the mouse gene by gene targeting. Homozygous tsg101-/- embryos fail to develop past day 6.5 of embryogenesis (E6.5), are reduced in size, and do not form mesoderm. Mutant embryos show a decrease in cellular proliferation in vivo and in vitro but no increase in apoptosis. Although levels of p53 transcripts were not affected in tsg101-/- embryos, p53 protein accumulated dramatically, implying altered posttranscriptional control of p53. In addition, transcription of the p53 effector, cyclin-dependent kinase inhibitor p21(WAF-1/CIP-1), was increased 5- to 10-fold, whereas activation of MDM2 transcription secondary to p53 elevation was not observed. Introduction of a p53 null mutation into tsg101-/- embryos rescued the gastrulation defect and prolonged survival until E8.5. These results demonstrate that tsg101 is essential for the proliferative burst before the onset of gastrulation and establish a functional connection between tsg101 and the p53 pathway in vivo.
authors.affiliation: Amgen Institute, 620 University Avenue, Toronto, ON, Canada M5G 2C1.
authors.forename: J
authors.initials: J
authors.lastname: Ruland
authors.forename: C
authors.initials: C
authors.lastname: Sirard
authors.forename: A
authors.initials: A
authors.lastname: Elia
authors.forename: D
authors.initials: D
authors.lastname: MacPherson
authors.forename: A
authors.initials: A
authors.lastname: Wakeham
authors.forename: L
authors.initials: L
authors.lastname: Li
authors.forename: J L
authors.initials: JL
authors.lastname: de la Pompa
authors.forename: S N
authors.initials: SN
authors.lastname: Cohen
authors.forename: T W
authors.initials: TW
authors.lastname: Mak
mesh_terms: D000818:Animals; D002455:Cell Division; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D020964:Embryo Loss / Q000378:metabolism*; D005314:Embryonic and Fetal Development; D004707:Endoderm / Q000378:metabolism; D056827:Endosomal Sorting Complexes Required for Transport; D015870:Gene Expression; D018390:Gene Targeting; D008648:Mesoderm / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051736:Proto-Oncogene Proteins c-mdm2; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D000099177:Tsg101 Protein
chemical_list: D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004268:DNA-Binding Proteins; D056827:Endosomal Sorting Complexes Required for Transport; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D051736:Proto-Oncogene Proteins c-mdm2; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; D000099177:Tsg101 Protein; C493957:Cdkn1a protein, mouse; C497207:Mdm2 protein, mouse