Development and Reproduction (한국발생생물학회지:발생과생식)

The Korean Society of Developmental Biology (한국발생생물학회)
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A Pumilio Activity Sensor Reveals Bag-of-Marbles Inhibition of Pum Activity in the Drosophila Ovary

  • Wijeong Jang (School of Biological Sciences and Technology, Chonnam National University) ;
  • Changsoo Kim (School of Biological Sciences and Technology, Chonnam National University)
  • Received : 2023.01.08
  • Accepted : 2023.03.17
  • Published : 2023.03.15
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Abstract

Pumilio (Pum) is an RNA-binding protein and translational repressor important to diverse biological processes. In the Drosophila ovary, Pum is expressed in female germline stem cells (GSCs), wherein it acts as an intrinsic stem cell maintenance factor via repressing target mRNAs that are as yet mostly unknown. Pum recognizes the Pum binding sequence (PBS) in the mRNA 3'UTR through its C-terminus Puf domain. Translational repression is mediated through its N-terminal domain, but the molecular mechanism remains largely unknown. We previously showed that Bag-of-marbles, a critical differentiation-promoting factor of female GSCs, physically interacts with the N-terminus of Pum. We further showed that this interaction is critical to Bam inhibition of Pum repressive action in cultured cells, but the physiological relevance was not addressed. Here we design an in vivo GFP translational reporter bearing the PBS in its 3'UTR and show that GFP expression is reduced in cells wherein Pum is known to be active. Furthermore, we demonstrate in pum mutant ovary that this GFP repression requires Pum, and also that the sensor faithfully monitors Pum activity. Finally, we show that forced expression of Bam inhibits Pum-mediated repression, validating that Bam inhibits Pum activity in vivo.

Keywords

Acknowledgement

This research was supported by grants from the National University Development Project 2021-4065/202233410001 (Changsoo Kim) and NRF-2020R1I1A1A01074292 (Wijeong Jang). We thank Dr. Cohen for the GFP translational reporter vector, which was used to make the Pum activity sensor. We are grateful to Dr. McKearin and Dr. Wharton for the flies.

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