Researchers at UT Southwestern Medical Center have developed a novel biochemical method that identifies proteins based on their specific locations within cells, leading to the discovery of a previously uncharacterized protein named calmin. This protein plays a crucial role in cell adhesion and movement, processes integral to cancer metastasis and cell differentiation. By combining CRISPR gene editing with an enzyme called TurboID, the team created a technique termed sub-organelle spatial proteomics. This approach allows for the mapping of protein landscapes within cellular structures, such as the endoplasmic reticulum (ER). Through this method, calmin was found to be enriched in the ER’s membrane tubules and associated with focal adhesions at the tips of actin fibers, suggesting its involvement in cell motility .
Further investigation revealed that calmin binds to F-actin, a component of the cytoskeleton, and influences the dynamics of focal adhesions—structures that mediate cell attachment to their environment. Depleting calmin in motile cells resulted in reduced movement and increased focal adhesions, while overexpression had the opposite effect, indicating calmin’s role in promoting adhesion turnover. This process appears to be regulated by calcium signaling from the ER. Given that calmin is frequently mutated in cancers, it may be pivotal in facilitating metastasis by enabling cancer cells to detach, migrate, and establish new tumors. Additionally, calmin’s presence in developing neurons suggests it may also contribute to neural development, a subject the researchers intend to explore further . Click for More Details
