title: MicroRNA-34c enhances murine male germ cell apoptosis through targeting ATF1.
abstract: BACKGROUND
  MicroRNAs (miRNAs) play vital regulatory roles in many cellular processes. The expression of miRNA (miR)-34c is highly enriched in adult mouse testis, but its roles and underlying mechanisms of action are not well understood.
  
  
  RESULTS
  In the present study, we show that miR-34c is detected in mouse pachytene spermatocytes and continues to be highly expressed in spermatids. To explore the specific functions of miR-34c, we have established an in vivo model by transfecting miR-34c inhibitors into primary spermatocytes to study the loss-of-function of miR-34c. The results show that silencing of miR-34c significantly increases the Bcl-2/Bax ratio and prevents germ cell from apoptosis induced by deprivation of testosterone. Moreover, ectopic expression of the miR-34c in GC-2 cell trigger the cell apoptosis with a decreased Bcl-2/Bax ratio and miR-34c inhibition lead to a low spontaneous apoptotic ratio and an increased Bcl-2/Bax ratio. Furthermore, ectopic expression of miR-34c reduces ATF1 protein expression without affecting ATF1 mRNA level via directly binding to ATF1's 3'UTR, indicating that ATF1 is one of miR-34c's target genes. Meanwhile, the knockdown of ATF1 significantly decreases the Bcl-2/Bax ratio and triggers GC-2 cell apoptosis. Inhibition of miR-34c does not decrease the GC-2 cell apoptosis ratio in ATF1 knockdown cells.
  
  
  CONCLUSIONS
  Our study shows for the first time that miR-34c functions, at least partially, by targeting the ATF1 gene in germ cell apoptosis, providing a novel mechanism with involvement of miRNA in the regulation of germ cell apoptosis.
authors.affiliation: State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, People's Republic of China.
authors.forename: Xiaoxuan
authors.initials: X
authors.lastname: Liang
authors.forename: Doudou
authors.initials: D
authors.lastname: Zhou
authors.forename: Chao
authors.initials: C
authors.lastname: Wei
authors.forename: Haoshu
authors.initials: H
authors.lastname: Luo
authors.forename: Jiali
authors.initials: J
authors.lastname: Liu
authors.forename: Rui
authors.initials: R
authors.lastname: Fu
authors.forename: Sheng
authors.initials: S
authors.lastname: Cui
mesh_terms: D051697:Activating Transcription Factor 1 / Q000235:genetics*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics*; D001483:Base Sequence; D002460:Cell Line; D004351:Drug Resistance / Q000235:genetics; D005260:Female; D005485:Flutamide / Q000494:pharmacology; D018507:Gene Expression Regulation, Developmental; D023061:Gene Order; D020868:Gene Silencing; D008297:Male; D051379:Mice; D035683:MicroRNAs / Q000378:metabolism*; D008969:Molecular Sequence Data; D013094:Spermatozoa / Q000187:drug effects / Q000378:metabolism*; D013737:Testis / Q000196:embryology / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D051697:Activating Transcription Factor 1; C497100:Atf1 protein, mouse; C551848:MIRN34a microRNA, mouse; D035683:MicroRNAs; D051028:bcl-2-Associated X Protein; D005485:Flutamide