The transacting factor CBF-A/Hnrnpab binds to the A2RE/RTS element of protamine 2 mRNA and contributes to its translational regulation during mouse spermatogenesis

PLoS Genet. 2013;9(10):e1003858. doi: 10.1371/journal.pgen.1003858. Epub 2013 Oct 17.


During spermatogenesis, mRNA localization and translation are believed to be regulated in a stage-specific manner. We report here that the Protamine2 (Prm2) mRNA transits through chromatoid bodies of round spermatids and localizes to cytosol of elongating spermatids for translation. The transacting factor CBF-A, also termed Hnrnpab, contributes to temporal regulation of Prm2 translation. We found that CBF-A co-localizes with the Prm2 mRNA during spermatogenesis, directly binding to the A2RE/RTS element in the 3' UTR. Although both p37 and p42 CBF-A isoforms interacted with RTS, they associated with translationally repressed and de-repressed Prm2 mRNA, respectively. Only p42 was found to interact with the 5'cap complex, and to co-sediment with the Prm2 mRNA in polysomes. In CBF-A knockout mice, expression of protamine 2 (PRM2) was reduced and the Prm2 mRNA was prematurely translated in a subset of elongating spermatids. Moreover, a high percentage of sperm from the CBF-A knockout mouse showed abnormal DNA morphology. We suggest that CBF-A plays an important role in spermatogenesis by regulating stage-specific translation of testicular mRNAs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CCAAT-Binding Factor / genetics*
  • CCAAT-Binding Factor / metabolism
  • Cytosol / metabolism
  • Gene Expression Regulation
  • Male
  • Mice
  • Mice, Knockout
  • Polyribosomes
  • Protamines / genetics
  • Protamines / metabolism*
  • Protein Biosynthesis*
  • RNA, Messenger / genetics
  • RNA-Binding Proteins / genetics*
  • RNA-Binding Proteins / metabolism
  • Spermatogenesis / genetics*
  • Testis / metabolism


  • CCAAT-Binding Factor
  • Nfyb protein, mouse
  • Protamines
  • RNA, Messenger
  • RNA-Binding Proteins
  • protamine 2

Grant support

This work was supported by grants from the Swedish Research Council (Vetenskapsrådet) and the Swedish Cancer Society (Cancerfonden) to PP. NF has been supported by postdoctoral research fellowships from the TOYOBO Foundation (Japan), from the Wenner-Gren Foundation (Sweden) and from the Swedish Research Council (Vetenskapsrådet). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.