title: Forced expression of cyclin D1 does not compensate for Id2 deficiency in the mammary gland.
abstract: Id2 and cyclin D1 share several biological activities, including inhibition of differentiation, stimulation of the G1-S transition in the cell cycle and stimulation of tumorigenesis. Mammary glands of Id2(-/-) mice display severely impaired lobulo-alveolar development during pregnancy, similarly to those of cyclin D1 null females. We investigated the functional relationship between Id2 and cyclin D1 in the mammary gland. Id2(-/-) mammary glands expressed a normal level of cyclin D1. No direct interaction of Id2 with cyclin D1 or its binding partner cdk4 was detected in mammalian two-hybrid assays. Ectopic expression of a cyclin D1 transgene did not rescue the mammary phenotype of Id2(-/-) mice. These results suggest that Id2 acts downstream or independently of cyclin D1 in the control of mammary cell proliferation during pregnancy.
authors.affiliation: Department of Biochemistry, Fukui Medical University, 23-3 Shimoaizuki, Matsuoka, 910-1193 Fukui, Japan.
authors.forename: Seiichi
authors.initials: S
authors.lastname: Mori
authors.forename: Kenji
authors.initials: K
authors.lastname: Inoshima
authors.forename: Yoko
authors.initials: Y
authors.lastname: Shima
authors.forename: Emmett V
authors.initials: EV
authors.lastname: Schmidt
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Yokota
mesh_terms: D000818:Animals; D019938:Cyclin D1 / Q000235:genetics / Q000378:metabolism*; D016213:Cyclins / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D005260:Female; D015870:Gene Expression; D051797:Inhibitor of Differentiation Protein 2; D008321:Mammary Glands, Animal / Q000033:anatomy & histology / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D010641:Phenotype; D011247:Pregnancy; D012097:Repressor Proteins; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*
chemical_list: D016213:Cyclins; D004268:DNA-Binding Proteins; C497452:Idb2 protein, mouse; D051797:Inhibitor of Differentiation Protein 2; D012097:Repressor Proteins; D014157:Transcription Factors; D019938:Cyclin D1