Proteomic profiling identifies a direct interaction between heat shock transcription factor 2 and the focal adhesion adapter talin‐1

Heat shock factor 2 (HSF2) is a versatile transcription factor that regulates gene expression under stress conditions, during development, and in disease. Despite recent advances in characterizing HSF2‐dependent target genes, little is known about the protein networks associated with this transcription factor. In this study, we performed co‐immunoprecipitation coupled with mass spectrometry analysis to identify the HSF2 interactome in mouse testes, where HSF2 is required for normal sperm development. Endogenous HSF2 was discovered to form a complex with several adhesion‐associated proteins, a finding substantiated by mass spectrometry analysis conducted in human prostate carcinoma PC‐3 cells. Notably, this group of proteins included the focal adhesion adapter protein talin‐1 (TLN1). Through co‐immunoprecipitation and proximity ligation assays, we demonstrate the conservation of the HSF2‐TLN1 interaction from mouse to human. Additionally, employing sequence alignment analyses, we uncovered a TLN1‐binding motif in the HSF2 C terminus that binds directly to multiple regions of TLN1 in vitro. We provide evidence that the 25 C‐terminal amino acids of HSF2, fused to EGFP, are sufficient to establish a protein complex with TLN1 and modify cell–cell adhesion in human cells. Importantly, this TLN1‐binding motif is absent in the C‐terminus of a closely related HSF family member, HSF1, which does not form a complex with TLN1. These results highlight the unique molecular characteristics of HSF2 in comparison to HSF1. Taken together, our data unveil the protein partners associated with HSF2 in a physiologically relevant context and identifies TLN1 as the first adhesion‐related HSF2‐interacting partner.