MicroRNA-34c enhances murine male germ cell apoptosis through targeting ATF1

PLoS One. 2012;7(3):e33861. doi: 10.1371/journal.pone.0033861. Epub 2012 Mar 30.

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.

Methodology/principal findings: 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/significance: 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Activating Transcription Factor 1 / genetics*
  • Animals
  • Apoptosis / drug effects
  • Apoptosis / genetics*
  • Base Sequence
  • Cell Line
  • Drug Resistance / genetics
  • Female
  • Flutamide / pharmacology
  • Gene Expression Regulation, Developmental
  • Gene Order
  • Gene Silencing
  • Male
  • Mice
  • MicroRNAs / metabolism*
  • Molecular Sequence Data
  • Spermatozoa / drug effects
  • Spermatozoa / metabolism*
  • Testis / embryology
  • Testis / metabolism
  • bcl-2-Associated X Protein / metabolism

Substances

  • Activating Transcription Factor 1
  • Atf1 protein, mouse
  • MIRN34a microRNA, mouse
  • MicroRNAs
  • bcl-2-Associated X Protein
  • Flutamide