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Non-canonical pathway for Rb inactivation and external signaling coordinate cell-cycle entry without CDK4/6 activity.

Authors :
Zhang, Mimi
Kim, Sungsoo
Yang, Hee Won
Source :
Nature Communications; 11/29/2023, Vol. 14 Issue 1, p1-15, 15p
Publication Year :
2023

Abstract

Cyclin-dependent kinases 4 and 6 (CDK4/6) are critical for initiating cell proliferation by inactivating the retinoblastoma (Rb) protein. However, mammalian cells can bypass CDK4/6 for Rb inactivation. Here we show a non-canonical pathway for Rb inactivation and its interplay with external signals. We find that the non-phosphorylated Rb protein in quiescent cells is intrinsically unstable, offering an alternative mechanism for initiating E2F activity. Nevertheless, this pathway incompletely induces Rb-protein loss, resulting in minimal E2F activity. To trigger cell proliferation, upregulation of mitogenic signaling is required for stabilizing c-Myc, thereby augmenting E2F activity. Concurrently, stress signaling promotes Cip/Kip levels, competitively regulating cell proliferation with mitogenic signaling. In cancer, driver mutations elevate c-Myc levels, facilitating adaptation to CDK4/6 inhibitors. Differentiated cells, despite Rb-protein loss, maintain quiescence through the modulation of c-Myc and Cip/Kip levels. Our findings provide mechanistic insights into an alternative model of cell-cycle entry and the maintenance of quiescence. Cyclin-dependent kinases (CDK4/6) play a crucial role in initiating cell growth. Here, Zhang et al. unveil a mechanism that bypasses CDK4/6, shedding light on an alternative pathway of cell-cycle initiation and quiescence maintenance. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
20411723
Volume :
14
Issue :
1
Database :
Complementary Index
Journal :
Nature Communications
Publication Type :
Academic Journal
Accession number :
173925427
Full Text :
https://doi.org/10.1038/s41467-023-43716-y