The poly(A)-binding protein partner Paip2a controls translation during late spermiogenesis in mice
Akiko Yanagiya, … , Bernard Robaire, Nahum Sonenberg
Akiko Yanagiya, … , Bernard Robaire, Nahum Sonenberg
Published August 25, 2010
Citation Information: J Clin Invest. 2010;120(9):3389-3400. https://doi.org/10.1172/JCI43350.
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Research Article

The poly(A)-binding protein partner Paip2a controls translation during late spermiogenesis in mice

Abstract

Translational control plays a key role in late spermiogenesis. A number of mRNAs encoding proteins required for late spermiogenesis are expressed in early spermatids but are stored as translationally inactive messenger ribonucleoprotein particles (mRNPs). The translation of these mRNAs is associated with shortening of their poly(A) tail in late spermiogenesis. Poly(A)-binding protein (Pabp) plays an important role in mRNA stabilization and translation. Three Pabp-interacting proteins, Paip1, Paip2a, and Paip2b, have been described. Paip2a is expressed in late spermatids. To investigate the role of Paip2 in spermiogenesis, we generated mice with knockout of either Paip2a or Paip2b and double-KO (DKO) mice lacking both Paip2a and Paip2b. Paip2a-KO and Paip2a/Paip2b-DKO mice exhibited male infertility. Translation of several mRNAs encoding proteins essential to male germ cell development was inhibited in late spermiogenesis in Paip2a/Paip2b-DKO mice, resulting in defective elongated spermatids. Inhibition of translation in Paip2a/Paip2b-DKO mice was caused by aberrant increased expression of Pabp, which impaired the interaction between eukaryotic initiation factor 4E (eIF4E) and the cap structure at the 5′ end of the mRNA. We therefore propose a model whereby efficient mRNA translation in late spermiogenesis occurs at an optimal concentration of Pabp, a condition not fulfilled in Paip2a/Paip2b-DKO mice.

Authors

Akiko Yanagiya, Geraldine Delbes, Yuri V. Svitkin, Bernard Robaire, Nahum Sonenberg

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Figure 7

Translational control of late spermiogenesis by Paip2a.

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Translational control of late spermiogenesis by Paip2a. (A) Excess amoun...
(A) Excess amounts of PABP inhibit translation in vitro. Control (lane 1) or Pabp-depleted Krebs-2 cell extracts (lanes 2–10) were programmed with capped Luc(A98) mRNA (2 μg/ml). The translation in Pabp-depleted Krebs-2 extract was performed in the presence of increasing concentrations of recombinant PABP (lanes 2–10; 0, 1.5, 3.0, 4.5, 6.0, 12, 18, 24, and 30 μg/ml). Relative light units were measured, and the value in control (1,034,812 RLU) was set as 100%. Data are presented as mean ± SD. (B) Translation of capped Luc(A98) mRNA in Pabp-depleted Krebs-2 extract supplemented with excess PABP (30 μg/ml) was performed in the presence of increasing concentrations of recombinant GST-PAIP2A (lanes 1–7; 0, 2.5, 5.0, 10, 15, 20, and 30 μg/ml). Data are presented in RLU as mean ± SD. (C) Crosslinking of initiation factors to the cap structure. Control RRL (lanes 1 and 2) or Pabp-depleted RRL (lanes 3–5) was preincubated with control buffer (–) (lanes 1 and 3), 0.6 mM m7GDP (+) (lane 2), and PABP (15 or 30 μg/ml) (lanes 4 and 5, respectively). Oxidized [32P]cap-labeled Luc(A+) mRNA was then added. After reduction with NaIO4 and nuclease digestion, labeled proteins were analyzed by SDS-PAGE and autoradiography. Relative efficiencies of eIF4E crosslinking to the cap structure are indicated at the bottom. The value in control RRL (lane 1) was set as 100%. (D) Model of molecular mechanism of translational control in late spermiogenesis by Paip2a.