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Lineage specific composition of cyclin D–CDK4/CDK6–p27 complexes reveals distinct functions of CDK4, CDK6 and individual D‐type cyclins in differentiating cells of embryonic origin

Abstract.  Objectives: This article is to study the role of G(1)/S regulators in differentiation of pluripotent embryonic cells. Materials and methods: We established a P19 embryonal carcinoma cell‐based experimental system, which profits from two similar differentiation protocols producing endoderm...

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Detalles Bibliográficos
Autores principales: Bryja, V., Pacherník, J., Vondráček, J., Souček, K., Čajánek, L., Horvath, V., Holubcová, Z., Dvořák, P., Hampl, A.
Formato: Texto
Lenguaje:English
Publicado: Blackwell Publishing Ltd 2008
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2659368/
https://www.ncbi.nlm.nih.gov/pubmed/19040567
http://dx.doi.org/10.1111/j.1365-2184.2008.00556.x
Descripción
Sumario:Abstract.  Objectives: This article is to study the role of G(1)/S regulators in differentiation of pluripotent embryonic cells. Materials and methods: We established a P19 embryonal carcinoma cell‐based experimental system, which profits from two similar differentiation protocols producing endodermal or neuroectodermal lineages. The levels, mutual interactions, activities, and localization of G(1)/S regulators were analysed with respect to growth and differentiation parameters of the cells. Results and Conclusions: We demonstrate that proliferation parameters of differentiating cells correlate with the activity and structure of cyclin A/E–CDK2 but not of cyclin D–CDK4/6–p27 complexes. In an exponentially growing P19 cell population, the cyclin D1–CDK4 complex is detected, which is replaced by cyclin D2/3–CDK4/6–p27 complex following density arrest. During endodermal differentiation kinase‐inactive cyclin D2/D3–CDK4–p27 complexes are formed. Neural differentiation specifically induces cyclin D1 at the expense of cyclin D3 and results in predominant formation of cyclin D1/D2–CDK4–p27 complexes. Differentiation is accompanied by cytoplasmic accumulation of cyclin Ds and CDK4/6, which in neural cells are associated with neural outgrowths. Most phenomena found here can be reproduced in mouse embryonic stem cells. In summary, our data demonstrate (i) that individual cyclin D isoforms are utilized in cells lineage specifically, (ii) that fundamental difference in the function of CDK4 and CDK6 exists, and (iii) that cyclin D–CDK4/6 complexes function in the cytoplasm of differentiated cells. Our study unravels another level of complexity in G(1)/S transition‐regulating machinery in early embryonic cells.