Site-Specific Phosphoproteomic Profiling of CAV1 Reveals Co-Regulatory Kinase Networks in Cancer Signaling

Caveolin-1 (CAV1) is a 21 kDa Vesicular Integral-membrane Protein essential for the biogenesis of caveolae, invaginations of the plasma membrane that coordinate membrane trafficking, lipid homeostasis, and signal transduction. CAV1 functions as a scaffolding platform that integrates mechanotransduction, endocytosis, and cellular stress responses, thereby modulating vascular integrity, inflammation, metabolism, and tumorigenesis. To comprehensively understand the phosphorylation landscape of CAV1, global phosphoproteomic datasets and their corresponding experimental metadata were systematically curated and integrated from previously published human cellular studies. The phosphorylation sites with the highest detection frequency across these datasets were considered predominant phosphorylation sites. To assess their functional relevance, phosphosites in other proteins (PsOPs) co-regulated with the predominant CAV1 sites, along with their upstream kinases and high-confidence protein-protein interaction partners, were systematically analyzed. Analysis of global human cellular phosphoproteome datasets revealed that tyrosine 14 (Y14) and serine 37 (S37) of CAV1 are the most frequently detected phosphosites across diverse experimental conditions. Notably, many of the co-regulated proteins obtained were associated with carcinogenesis, apoptosis, and cell cycle regulation, including MET and ERBB2. Our analysis revealed SRC, ABL2, ERBB2, ERBB3, LYN, and TEC as potential upstream kinases of CAV1_Y14, whereas CSNK1E and GRK5 were predicted to regulate CAV1_S37. Considering the challenges associated with site-specific interrogation, we employed a global co-regulation analysis approach to characterize CAV1 phosphorylation dynamics. Our findings reveal that key CAV1 phosphosites modulate oncogenic signaling, cytoskeletal remodeling, and membrane organization, providing novel insights into CAV1-mediated cellular functions and its context-dependent role in tumor progression.