Reference : PhD Bruno Kieffer
The androgen receptor (AR) controls cell proliferation, development of sexual characteristics, behavior, muscle's mass and strength, and bone density. As a member of the NR superfamily, AR shares a common architecture including a ligand binding domain (LBD), a DNA binding domain (DBD) involved in the recognition of hormone specific response elements and an intrinsically disordered amino-terminal domain (AR-NTD). In contrast to other nuclear receptors, the AR carries one of the largest NTD that represents about 60% of the AR sequence. Naturally occurring mutations in the AR gene, especially in the region encoding its NTD have been linked to diverse physiological defects including androgen insensitivity syndrome, spinal bulbar muscle atrophy (SBMA), diabetes or gynecomastia. AR plays a key role in some hormone-related human tumors such as in prostate cancer where AR is the main factor controlling the tumor progression into a castration-resistant and incurable disease. A number of AR variants have been identified in patients arising during androgen ablation therapy. These mutations confer to the AR new functional properties allowing the AR to support cell growth and survival under low levels of androgens. Mutations are distributed throughout the AR sequence in both folded and disordered domains. In the folded LBD and DBD, they usually result in altered binding properties, with loss of specificity for the cognate ligand or DNA response elements. Also, a number of AR variants that display ligand-independent transcriptional activities have been identified. Preliminary studies on these AR variants suggest that they lead to differential gene expression when compared with the wild type AR.
The present project aims at bridging the gap between the identification of pathological variants of AR in patients, their functional characterization and a biophysical description of their dynamical properties at the single-cell level. To achieve this goal, a consortium gathering two teams with complementary expertise in biophysics, molecular biology and cell imaging has been setup. First, functional properties of a chosen list of AR mutations in terms of protein-protein interactions, chaperoning, gene regulation will be assessed by « omics » approaches. Secondly, how the mutations affect AR translocation dynamics from the cytoplasm to the nucleus will be investigated by live-cell imaging of tagged AR variants. Also, the nuclear diffusion dynamics of the same AR variants will be characterized by using fluorescence loss in photobleaching in collaboration with Nacho Molina’s team. Ultimately, omics and single-cell imaging data will be integrated to better understand the basic dynamic properties of pathological AR variants. This multidisciplinary research program might contribute to the development of innovative treatments against pathological AR variants in a larger spectra of human diseases.
Acquired skills at the end of the PhD thesis: live-cell imaging; fluorescence loss in photobleaching; Image analysis; ODE modeling of biochemical reactions ; Integrative analysis of omics data.
Candidate’s background: Molecular and cellular biology ; Proteomics ; Cell imaging; Fluorescence microscopy.
Application Deadline : Nov. 1, 2018