First published online July 10, 2007
Development 134, 1505e (2007)
© The Company of Biologists Limited
Spermatogenesis: lost in translational control
Translational control is crucial for the correct timing of developmental
events such as spermatogenesis that take place in the absence of
transcription. In this issue of Development, two papers describe the
role of eIF4G2 - a novel orthologue of eukaryotic initiation factor 4G (eIF4G)
- in translational control of spermatogenesis in Drosophila. eIF4G
acts as a scaffold protein in the eIF4F translation initiation complex. On
p. 2851,
Franklin-Dumont et al. report that eIF4G2, which they call Off-schedule (Ofs),
couples translational control to meiosis and differentiation during
spermatogenesis. They show that, during the meiotic G2 phase of
spermatogenesis, ofs mutant germ cells do not reach their correct
size and fail to undergo meiosis or differentiate significantly. Furthermore,
they report, the accumulation of four cell cycle regulators (Cyclin A, Boule,
Twine and Roughex) is altered. They also show that Ofs has eIF4G activity and
suggest that it substitutes for this protein in spermatocytes. Given these
results, Franklin-Dumont and colleagues speculate that spermatocytes must
accumulate sufficient cell mass (a process that requires active translation)
before they can execute meiosis and differentiation, and that a checkpoint
stops these processes if the spermatocytes have not grown enough. On
p. 2863, Baker and
Fuller also provide evidence that translational control regulates meiosis and
differentiation in Drosophila spermatocytes. They report that flies
mutant for eIF4G2 are viable but that the males are sterile. They then show
that, although spermatocytes form in the mutant flies, the germ cells skip the
major events of the meiotic divisions. eIF4G2 function, they report, is needed
for the normal accumulation of the core cell cycle regulators Twine and Cyclin
B in mature spermatocytes; loss of eIF4G2 function also causes widespread
defects in spermatid differentiation, including a failure to elongate
properly. Thus, suggest Baker and Fuller, a specialized form of the
translation initiation machinery is required for the regulation and execution
of key steps in male germ cell differentiation. Together, these two papers
thus provide important new insights into how translational control ensures
that the meiotic cell cycle is coordinated with differentiation during
spermatogenesis to produce viable spermatozoa.
Related articles in Development:
- A novel eIF4G homolog, Off-schedule, couples translational control to meiosis and differentiation in Drosophila spermatocytes
- Tina M. Franklin-Dumont, Chandrima Chatterjee, Steven A. Wasserman, and Stephen DiNardo
Development 2007 134: 2851-2861.
[Abstract]
[Full Text]
- Translational control of meiotic cell cycle progression and spermatid differentiation in male germ cells by a novel eIF4G homolog
- Catherine C. Baker and Margaret T. Fuller
Development 2007 134: 2863-2869.
[Abstract]
[Full Text]
