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Nuclear mislocalization of enzymatically active RanGAP causes segregation distortion in Drosophila
A Kusano1, C Staber, B Ganetzky
1Laboratory of Genetics, University of Wisconsin-Madison, 53706, USA.
Developmental Cell
|November 13, 2001
Summary
Segregation Distorter (SD) causes preferential chromosome transmission in Drosophila by mislocalizing a truncated RanGAP protein to nuclei. This disrupts nuclear transport and leads to sperm dysfunction.
Area of Science:
- Genetics
- Molecular Biology
- Developmental Biology
Background:
- Segregation Distorter (SD) is a genetic system in Drosophila inducing biased inheritance.
- SD functions by causing the dysfunction of sperm carrying the wild-type chromosome.
- The Sd locus encodes a truncated Ran GTPase activating protein (RanGAP).
Purpose of the Study:
- To investigate the molecular mechanism of meiotic drive by Segregation Distorter.
- To determine the role of the truncated Sd-RanGAP protein in the distortion process.
- To elucidate how Sd-RanGAP affects nuclear transport and sperm function.
Main Methods:
- Analyzing the enzymatic activity and subcellular localization of Sd-RanGAP.
- Perturbing Sd-RanGAP's enzymatic activity and nuclear localization.
- Overexpressing Ran and RanGEF in the male germline.
- Assessing nuclear transport using a GFP reporter in salivary glands.
Main Results:
- Sd-RanGAP retains enzymatic activity but is mislocalized to nuclei.
- Disruption of Sd-RanGAP's activity or nuclear localization abolishes distortion.
- Overexpression of Ran or RanGEF suppresses distortion.
- SD impairs nuclear transport of a GFP reporter.
Conclusions:
- Mislocalization of Sd-RanGAP disrupts the nuclear Ran signaling pathway by reducing nuclear RanGTP.
- This disruption leads to sperm dysfunction and meiotic drive.
- SD imposes a defect in nuclear transport, potentially explaining sperm dysfunction.
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