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Polo-mediated phosphorylation of Maelstrom regulates oocyte determination during oogenesis in Drosophila

Jun Wei Pek1, Bing Fu Ng, Toshie Kai

  • 1Temasek Life Sciences Laboratory, 1 Research Link National University of Singapore, Singapore 117604.

Development (Cambridge, England)
|November 9, 2012
PubMed

Insights

Maelstrom phosphorylation by Polo kinase regulates oocyte determination in Drosophila. This process involves repressing Sir2, independent of transposon silencing and stem cell differentiation.

Area of Science:

  • Developmental Biology
  • Molecular Genetics
  • RNA Biology

Background:

  • Maelstrom (Mael) is crucial in Drosophila germline for transposon silencing via piRNA production.
  • Mael also regulates germline stem cell differentiation by repressing microRNA-7.
  • Oocyte determination is a critical developmental process in the female germline.

Purpose of the Study:

  • To investigate a novel role of Maelstrom in oocyte determination.
  • To elucidate the molecular mechanism linking Maelstrom phosphorylation to oocyte determination.
  • To identify the kinase responsible for Maelstrom phosphorylation in this context.

Main Methods:

  • Utilized Drosophila melanogaster as a model organism.
  • Investigated Maelstrom phosphorylation at serine 138.
  • Assayed Maelstrom's role in regulating Sir2 expression and the pachytene checkpoint.
  • Identified the kinase responsible for Maelstrom phosphorylation using genetic and biochemical approaches.

Main Results:

  • Maelstrom phosphorylation at serine 138 is essential for oocyte determination.
  • This phosphorylation event is required for repressing the pachytene checkpoint protein Sir2.
  • Maelstrom phosphorylation's role in oocyte determination is independent of its known functions in transposon silencing and germline stem cell differentiation.
  • Polo kinase was identified as the kinase that phosphorylates Maelstrom.

Conclusions:

  • Polo-mediated Maelstrom phosphorylation is a key mechanism controlling oocyte determination in Drosophila.
  • This phosphorylation inactivates the pachytene checkpoint by repressing Sir2.
  • This study reveals a new function for Maelstrom in germline development, separate from its roles in transposon control and stem cell maintenance.

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