This article identifies the small GTPase RHOA as a critical controller of mitochondria-endoplasmic reticulum contact sites (MERCS). Through a genome-wide screen, scientists discovered that RHOA facilitates organelle communication by directly binding to the ER protein VAPB, which stabilizes its interaction with the mitochondrial protein PTPIP51. The study demonstrates that manipulating RHOA levels—either through its degradation via the CUL3 pathway or through pharmacological means—directly impacts essential functions like calcium transfer and metabolic remodeling. Furthermore, the authors reveal that disease-related mutations in these proteins disrupt this tethering mechanism, potentially contributing to cancer, hypertension, and neurodegenerative disorders like ALS. Ultimately, the findings establish RHOA as a molecular switch that tunes inter-organellar proximity, offering new insights into cellular health and potential therapeutic targets.

References:

• Yang Z, Nakajima S, Chen H, et al. RHOA regulates mitochondria-ER contact sites through modulation of the VAPB/PTPIP51 tether[J]. Nature Communications, 2025.