Bodra, N. | bioRxiv Science

bioRxiv2026

Interdependent androgen and glucocorticoid receptor signalling shapes prostate epithelial homeostasis

Androgen signalling is essential for prostate secretory functions and epithelial cell maintenance, yet how this signal is translated into a transcriptional output remains poorly understood. Androgens functions are primarily mediated by the androgen receptor (AR), which binds hormone response elements similar to those of other steroid receptors, including the glucocorticoid receptor (GR). Here we show that AR and GR are co-expressed in the prostate epithelium, and co-located within nuclear foci. Moreover, GR promotes the formation and dynamics of AR nuclear condensates, and heterodimerizes with AR in a ligand-binding domain-dependent manner. In addition, subtle variations within the hormone response element sequence direct the co-recruitment of AR and GR into activator or repressor complexes to activate or repress gene expression. Finally, prostate-specific deletion of GR in mice disrupts AR nuclear distribution, impairs AR-dependent gene networks involved in epithelial maintenance, and promotes the expression of genes involved in metabolism and cell cycle, resulting in altered tissue homeostasis. Thus, these findings identify GR as an integral component of the AR transcriptional machinery in epithelial cells of the healthy prostate, and reveal how shared cis-regulatory elements are interpreted to generate distinct transcriptional outcomes.

cell biology↗

bioRxiv2025

Mechanisms involved in the lipid membrane tubulation activity of the pH-responsive MakA protein from Vibrio cholerae

Bacterial pore-forming toxins (PFTs) are key virulence factors that disrupt host cell membranes. The Vibrio cholerae cytotoxin MakA, a member of the ClyA structural family of -PFTs, exhibits a unique, pH-dependent ability to induce lipid membrane tubulation. This study elucidates the molecular mechanisms underlying this process. We identify the N-terminal histidine residue (His30) of MakA as a critical pH sensor that is indispensable for membrane tubulation but not required for membrane binding and cell lysis. Substitution of His30 with lysine, MakAH30K , abrogated tubulation without affecting membrane insertion, instead triggering aberrant membrane fusion events. Circular dichroism spectroscopy analysis revealed that the MakAH30K substitution attenuates the robust -helical transition observed in wild-type MakA upon lipid membrane binding, providing a molecular explanation for its functional defect. Furthermore, we established that membrane cholesterol contributes to MakA-induced tubulation of lipid membranes, as its absence or mutation of a putative cholesterol-binding motif MakAI236D&I237D abolishes both membrane association and tubule formation. A key implication of our work is the mechanistic uncoupling of membrane tubulation from cytolysis, revealing that MakA can perturb membranes via distinct pathways. These findings define a sophisticated activation mechanism where His30 protonation in the acidic host environment and specific cholesterol binding synergistically drive the conformational change necessary for helical oligomerization and membrane tubulation. We discuss our findings from the viewpoint of possible convergent evolution, where bacterial PFTs like MakA partly may mimic ancient membrane remodelers involved in membrane repair pathways, such as ESCRT-III, but for bacterial fitness in host interactions and pathogenesis. Moreover, the present study provides a foundation for possible development of therapeutic strategies aimed at inhibiting these critical interactions.

biochemistry↗