Cyclin-dependent kinase 2-associating protein 1 commits murine embryonic stem cell differentiation through retinoblastoma protein regulation.
Mouse embryonic stem cells (mESCs) maintain pluripotency and indefinite self-renewal through yet to be defined molecular mechanisms. Leukemia inhibitory factor has been utilized to maintain the symmetrical self-renewal and pluripotency of mESCs in culture. It has been suggested that molecules with significant cellular effects on retinoblastoma protein (pRb) or its related pathways should have functional impact on mESC proliferation and differentiation. However, the involvement of pRb in pluripotent differentiation of mESCs has not been extensively elaborated. In this paper, we present novel experimental data indicating that Cdk2ap1 (cyclin-dependent kinase 2-associating protein 1), an inhibitor of G(1)/S transition through down-regulation of CDK2 and an essential gene for early embryonic development, confers competency for mESC differentiation. Targeted disruption of Cdk2ap1 in mESCs resulted in abrogation of leukemia inhibitory factor withdrawal-induced differentiation, along with altered pRb phosphorylation. The differentiation competency of the Cdk2ap1(-/-) mESCs was restored upon the ectopic expression of Cdk2ap1 or a nonphosphorylatable pRb mutant (mouse Ser(788) --> Ala), suggesting that the CDK2AP1-mediated differentiation of mESCs was elicited through the regulation of pRb. Further analysis on mESC maintenance or differentiation-related gene expression supports the phosphorylation at serine 788 in pRb plays a significant role for the CDK2AP1-mediated differentiation of mESCs. These data clearly demonstrate that CDK2AP1 is a competency factor in the proper differentiation of mESCs by modulating the phosphorylation level of pRb. This sheds light on the role of the establishment of the proper somatic cell type cell cycle regulation for mESCs to enter into the differentiation process.
Kim
Yong
Y
School of Dentistry and Dental Research Institute, UCLA, Los Angeles, CA 90095, USA. thadyk@ucla.edu
Deshpande
Amit
A
Dai
Yanshan
Y
Kim
Jeffrey J
JJ
Lindgren
Anne
A
Conway
Anne
A
Clark
Amander T
AT
Wong
David T
DT
D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D051357:Cyclin-Dependent Kinase 2 / Q000235:genetics / Q000378:metabolism; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000378:metabolism; D005786:Gene Expression Regulation; D051379:Mice; D018345:Mice, Knockout; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D016160:Retinoblastoma Protein / Q000235:genetics / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*
D016160:Retinoblastoma Protein; D025521:Tumor Suppressor Proteins; D011494:Protein Kinases; C496849:Cdk2ap1 protein, mouse; D051357:Cyclin-Dependent Kinase 2