title: The anaphase-promoting complex coordinates initiation of lens differentiation.
abstract: Lens development requires the precise coordination of cell division and differentiation. The mechanisms by which the differentiation program is initiated after cell cycle arrest remains not well understood. Cyclin-dependent kinase inhibitors (CKIs), such as p15 and p21, have been suggested to be critical components that inhibit G1 progression and therefore, their activation is necessary for quiescence and important for the onset of differentiation. Regulation of p15 and p21 is principally governed by transforming growth factor (TGF)-beta-signaling pathway. We have identified that Cdh1/APC, a critical ubiquitin protein ligase, plays an important role in regulating lens differentiation by facilitating TGF-beta-induced degradation of SnoN, a transcriptional corepressor that needs to be removed for transcriptional activation of p15 and p21. The depletion of Cdh1 by RNA interference attenuates the TGF-beta-mediated induction of p15 and p21 and significantly blocks lens differentiation. Expression of nondegradable SnoN also noticeably attenuates lens induction. Furthermore, we have shown that Cdh1 and SnoN form a complex at the onset of lens differentiation. In vivo histological analysis confirms our biochemical and genetic results. Thus, Cdh1/APC is crucial to the coordination of cell cycle progression and the initiation of lens differentiation through mediating TGF-beta-signaling-induced destruction of SnoN.
authors.affiliation: University of Pittsburgh Cancer Institute, Pittsburgh, PA 15312, USA.
authors.forename: George
authors.initials: G
authors.lastname: Wu
authors.forename: Sara
authors.initials: S
authors.lastname: Glickstein
authors.forename: Weijun
authors.initials: W
authors.lastname: Liu
authors.forename: Takeo
authors.initials: T
authors.lastname: Fujita
authors.forename: Wenqi
authors.initials: W
authors.lastname: Li
authors.forename: Qi
authors.initials: Q
authors.lastname: Yang
authors.forename: Robert
authors.initials: R
authors.lastname: Duvoisin
authors.forename: Yong
authors.initials: Y
authors.lastname: Wan
mesh_terms: D000595:Amino Acid Sequence; D064173:Anaphase-Promoting Complex-Cyclosome; D000818:Animals; D002454:Cell Differentiation; D050762:Cyclin-Dependent Kinase Inhibitor p15 / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling; D007908:Lens, Crystalline / Q000166:cytology*; D051379:Mice; D008954:Models, Biological; D008969:Molecular Sequence Data; D011499:Protein Processing, Post-Translational; D012097:Repressor Proteins / Q000737:chemistry; D015398:Signal Transduction; D013379:Substrate Specificity; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000378:metabolism; D043743:Ubiquitin-Protein Ligase Complexes / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism
chemical_list: D050762:Cyclin-Dependent Kinase Inhibitor p15; D050759:Cyclin-Dependent Kinase Inhibitor p21; D005136:Eye Proteins; D012097:Repressor Proteins; D016212:Transforming Growth Factor beta; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D044767:Ubiquitin-Protein Ligases