Abstract
p44/MEP50/WDR77 has been identified as a coactivator of androgen receptor (AR), with distinct growth suppression and promotion function in gender specific endocrine organs and their malignancies. We dissected the functional domains of p44 for protein interaction with transcription factors, transcriptional activation, as well as the functional domains in p44 related to its growth inhibition in prostate cancer. Using a yeast two-hybrid screen, we identified a novel transcription complex AR-p44-Smad1, confirmed for physical interaction by co-immunoprecipitaion and functional interaction with luciferase assays in human prostate cancer cells. Yeast two-hybrid assay revealed that the N-terminal region of p44, instead of the traditional WD40 domain at the C-terminus, mediates the interaction among p44, N-terminus of AR and full length Smad1. Although both N and C terminal domains of p44 are necessary for maximum AR transcriptional activation, the N terminal fragment of p44 alone maintains the basic effect on AR transcriptional activation. Cell proliferation assays with N- and C- terminal deletion mutations indicated that the central portion of p44 is required for nuclear p44 mediated prostate cancer growth inhibition.
Highlights
Prostate cancer (PCa) is the most common malignancy in men in the United States
Since both proteins are known to be involved in androgen receptor (AR)-mediated gene regulation, we decided to test whether the introduction of AR into the two-hybrid system will restore p44-Smad1 interaction
Coexpression of Smad1, p44, and AR resulted in a positive two-hybrid signal (Fig. 1A, B), suggesting that AR binds both to p44-LexA, and Smad1-B42, recruiting the transcription activation domain to the promoter and activating reporter gene expression
Summary
Prostate cancer (PCa) is the most common malignancy in men in the United States. In 2011, prostate cancer alone leads to 29% of all newly diagnosed cancers and is the second leading cause of death as a result of cancer [1]. Androgen receptor (AR) is the essential mediator of androgen action and plays an important role in regulating prostate development and differentiation, as well as cancer cell growth and progression [2]. An increasing number of AR cofactors have been identified in recent studies [5,6,7]. Overexpression of Androgen Receptor Trapped clone-27 (ART-27), an AR coactivator, inhibits androgen-mediated cellular proliferation in androgen-dependent cancer cells [10,11]. Overexpression of AR-associated (ARA) coactivator ARA70a inhibits LNCaP cell proliferation [8]. P44 has been identified as an AR coactivator and overexpression of nuclear p44 caused growth arrest both in in vitro cell proliferation and in vivo tumor xenografts in AR-dependent manner [9]. Two nuclear export signal (NES) and three nuclear localization signal (NLS) sequences related to its cellular localization have been reported in the p44/WDR77 protein [12]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
