Tissue‐specific response of the RB‐E2F1 complex during mammalian hibernation. Issue 9 (9th August 2022)

• Record Type: Journal Article
• Authors: Singh, Gurjit; Bloskie, Tighe; Storey, Kenneth B.
• Other Names: Stevenson Tyler guestEditor.
• Is Part Of: Journal of experimental zoology. Volume 337:Issue 9/10(2022)
• Page Start: 1002
• Page End: 1009
• Publication Date: 2022-08-09
• Subjects: cell cycle -- hibernation -- histone methyl transferase -- metabolic rate depression -- phosphorylation -- retinoblastoma protein -- transcription factor; Zoology -- Periodicals; Zoology; Animal Population Groups -- physiology; Zoology; Electronic journals; Periodical; Periodicals; 590
• DOI: 10.1002/jez.2648
• Languages: English
• ISSNs: 2471-5646

Abstract

Abstract: Metabolic rate depression during prolonged bouts of torpor is characteristic of mammalian hibernation, reducing energy expenditures over the winter. Cell cycle arrest is observed in quiescent cells during dormancy, partly due to the retinoblastoma (Rb) protein at G1 /S, given cell division and proliferation are metabolic‐costly processes. Rb binds to E2F transcription factors and recruits corepressors (e.g., SUV39H1) to E2F target genes, blocking their transcription and cell cycle passage. Phosphorylation by cyclin‐CDK complexes at S780 or S795 abolishes Rb‐mediated repression, allowing transition into S phase. The present study compares Rb‐E2F1 responses between euthermic and torpid states in five organs (brain, heart, kidney, liver, skeletal muscle) of 13‐lined ground squirrels ( Ictidomys tridecemlineatus ). Immunoblotting assessed the expression of Rb, pRb (S780, S795), E2F1, and SUV39H1. Our findings demonstrate multi‐tissue upregulation of Rb and SUV39H1 during torpor, with tissue‐specific changes to E2F1 and pRb (S780), suggesting Rb‐E2F1 contributes to cell cycle control in hibernation. Abstract : Rb binds to E2F1 transcription factors and recruits corepressors (e.g., SUV39H1) to E2F1 target genes, blocking their transcription and cell cycle passage. Phosphorylation by cyclin‐CDK complexes at S780 or S795 abolishes Rb‐mediated repression, allowing transition into S phase. Our findings demonstrate multi‐tissue upregulation of Rb and SUV39H1 during torpor, with tissue‐specific changes to E2F1 and pRb (S780), suggesting Rb‐E2F1 contributes to energy conservation in hibernation. Highlights: Tissue‐specific regulation of the Rb‐E2F1 pathway in 13‐lined ground squirrel. Rb repress E2F1, and Suv39H1 can act as additional factor in cell cycle repression in brain, kidney and liver. Possibility of alternate of roles of E2F1 in the heart and liver during hibernation.