Steroidogenic Factor 1 (NR5A1) Maintains Centrosome Homeostasis in Steroidogenic Cells by Restricting Centrosomal DNA-Dependent Protein Kinase Activation

Abstract

Steroidogenic factor 1 (SF-1 or NR5A1) is a nuclear receptor that controls adrenogenital cell growth and differentiation. Adrenogenital primordial cells from SF-1 knockout mice die of apoptosis, but the mechanism by which SF-1 regulates cell survival is not entirely clear. Besides functioning in the nucleus, SF-1 also resides in the centrosome and controls centrosome homeostasis. Here, we show that SF-1 restricts centrosome overduplication by inhibiting aberrant activation of DNA-dependent protein kinase (DNA-PK) in the centrosome. SF-1 was found to be associated with Ku70/Ku80 only in the centrosome, sequestering them from the catalytic subunit of DNA-PK (DNA-PKcs). In the absence of SF-1, DNA-PKcs was recruited to the centrosome and activated, causing aberrant activation of centrosomal Akt and cyclin-dependent kinase 2 (CDK2)/cyclin A and leading to centrosome overduplication. Centrosome overduplication caused by SF-1 depletion was averted by the elimination of DNA-PKcs, Ku70/80, or cyclin A or by the inhibition of CDK2 or Akt. In the nucleus, SF-1 did not interact with Ku70/80, and SF-1 depletion did not activate a nuclear DNA damage response. Centriole biogenesis was also unaffected. Thus, centrosomal DNA-PK signaling triggers centrosome overduplication, and this centrosomal event, but not the nuclear DNA damage response, is controlled by SF-1.

SUPPLEMENTAL MATERIAL

Supplemental material for this article may be found at http://dx.doi.org/10.1128/MCB.01064-12.

ACKNOWLEDGMENTS

We thank Cheng-Hsilin Hsieh for technical assistance in mass spectrometry, Tang K. Tang for the anti-CPAP and anti-SAS6 antibodies, and Chung Wang for the anti-Hsc70 antibodies. RNAi reagents were obtained from the National RNAi Core Facility located at the Institute of Molecular Biology/Genomic Research Center, Academia Sinica, supported by the National Research Program for Genomic Medicine, NSC 97-3112-B-001-016.

This work was supported by grants from Academia Sinica and the National Science Council, Taiwan (NSC100-2321-B-001-006).