The E2F family of transcription factors is crucial for cell cycle progression and cell fate decisions.Although E2Fs have been widely studied in mammals,there have been few studies performed in insects.Here,we determin...The E2F family of transcription factors is crucial for cell cycle progression and cell fate decisions.Although E2Fs have been widely studied in mammals,there have been few studies performed in insects.Here,we determined the function of E2F4 in the silkworm,Bombyx mori.We demonstrate that E2F proteins are highly conserved among species from lower animals to higher mammals.Overexpression of the BmE2F4 gene led to cell cycle arrest in the G1 phase,whereas interfering with the BmE2F4 mRNA led to accumulation of cells in the S phase.These results indicate that BmE2F4 is important in cell cycle regulation.We also demonstrate that the BmE2F4 gene is involved in DNA replication of BmN-SWU1 cells and DNA synthesis in the silk gland.Furthermore,we identified a protein called Bm14-3-3ζthat can interact with BmE2F4 and allow it to localize in the nucleus.Overexpression of the Bm14-3-3ζgene led to cell cycle arrest in the G1 phase,while knocking down the gene increased the proportion of cells in S phase.These findings provide important insights into the function of E2F transcription factors and increase our understanding of their involvement in cell cycle regulation.展开更多
Our earlier studies have demonstrated that the cigarette smoke in the form of cigarette smoke condensate(CSC)causes growth arrest of a mouse spermatocyte cell line[GC-2spd(ts)]through activation of the AHR–NRF2 pathw...Our earlier studies have demonstrated that the cigarette smoke in the form of cigarette smoke condensate(CSC)causes growth arrest of a mouse spermatocyte cell line[GC-2spd(ts)]through activation of the AHR–NRF2 pathway.The present study demonstrates the CSC-activated p38 and ERK MAPK signaling in GC-2spd(ts)via arylhydrocarbon receptor(AHR).Pharmacological inhibition by using AHR-antagonist,or p38 MAPK and ERK(MEK1)inhibitors significantly abrogates CSC-induced growth arrest by AHR and MAPK inactivation.QRT-PCR,western blot,and immunofluorescence of Ahr-target of Nrf2,and stress-inducible growth suppressive Atf3 and E2f4 following treatments indicate a crosstalk among these pathways.Regulation of Atf3 by Nrf2 and Ahr through RNA interference suggests the existence of a cross-regulatory loop between the targets.CSC induction of E2f4 via Atf3 and its regulation by pharmacological inhibitors reveal a possible regulatory mechanism of growth inhibitory CSC.SiRNA silencing of Ahr,Nrf2,Atf3,and E2f4 genes and downregulation of cyclins by CSC corroborate the growth inhibitory effect of cigarette smoke.Thus,the data obtained suggest that the CSC-mediated MAPKs and AHR–NRF2 crosstalks lay the molecular basis for the growth arrest and cell death of spermatocytes.展开更多
基金We thank Dr.Jiangbo Song for phylogenetic analysis.This research was funded by National Natural Science Foundation of China(31872428 and 31872427)Natural Science Foundation of Chongqing(cstc2019jcyj-msxmX0096 and estc 2020jscx-msxmX0045)China Agriculture Research System(CARS-18).
文摘The E2F family of transcription factors is crucial for cell cycle progression and cell fate decisions.Although E2Fs have been widely studied in mammals,there have been few studies performed in insects.Here,we determined the function of E2F4 in the silkworm,Bombyx mori.We demonstrate that E2F proteins are highly conserved among species from lower animals to higher mammals.Overexpression of the BmE2F4 gene led to cell cycle arrest in the G1 phase,whereas interfering with the BmE2F4 mRNA led to accumulation of cells in the S phase.These results indicate that BmE2F4 is important in cell cycle regulation.We also demonstrate that the BmE2F4 gene is involved in DNA replication of BmN-SWU1 cells and DNA synthesis in the silk gland.Furthermore,we identified a protein called Bm14-3-3ζthat can interact with BmE2F4 and allow it to localize in the nucleus.Overexpression of the Bm14-3-3ζgene led to cell cycle arrest in the G1 phase,while knocking down the gene increased the proportion of cells in S phase.These findings provide important insights into the function of E2F transcription factors and increase our understanding of their involvement in cell cycle regulation.
基金This material is based upon work supported by the Department of Veterans Affairs,Veterans Health Administration,Biomedical Laboratory Research and Development Award#I01BX007080.
文摘Our earlier studies have demonstrated that the cigarette smoke in the form of cigarette smoke condensate(CSC)causes growth arrest of a mouse spermatocyte cell line[GC-2spd(ts)]through activation of the AHR–NRF2 pathway.The present study demonstrates the CSC-activated p38 and ERK MAPK signaling in GC-2spd(ts)via arylhydrocarbon receptor(AHR).Pharmacological inhibition by using AHR-antagonist,or p38 MAPK and ERK(MEK1)inhibitors significantly abrogates CSC-induced growth arrest by AHR and MAPK inactivation.QRT-PCR,western blot,and immunofluorescence of Ahr-target of Nrf2,and stress-inducible growth suppressive Atf3 and E2f4 following treatments indicate a crosstalk among these pathways.Regulation of Atf3 by Nrf2 and Ahr through RNA interference suggests the existence of a cross-regulatory loop between the targets.CSC induction of E2f4 via Atf3 and its regulation by pharmacological inhibitors reveal a possible regulatory mechanism of growth inhibitory CSC.SiRNA silencing of Ahr,Nrf2,Atf3,and E2f4 genes and downregulation of cyclins by CSC corroborate the growth inhibitory effect of cigarette smoke.Thus,the data obtained suggest that the CSC-mediated MAPKs and AHR–NRF2 crosstalks lay the molecular basis for the growth arrest and cell death of spermatocytes.
