Biology subjects

Palm, W.

Publications and source records attributed to Palm, W..

3 recordsLinked to original sources

bioRxiv2025

Mammalian RAVE couples V-ATPase assembly to organelle acidification and function

Acidification of lysosomes, endosomes, and the Golgi underpins organelle-specific functions within the endomembrane system. This process is driven by vacuolar-type H-ATPases (V-ATPases), which reversibly assemble from peripheral V and membrane-integral V domains to regulate organelle pH. In yeast, V-V assembly at the vacuole is mediated by the RAVE complex, but V-ATPase assembly in mammalian cells remains less well understood. Here, we systematically define physiological roles of mammalian RAVE. Under basal conditions, mRAVE broadly promotes V-ATPase assembly and organelle acidification. Upon mTORC1 inactivation, mRAVE is recruited to lysosomes and required for the resulting increase in V-ATPase assembly and catabolic activity. Loss of mRAVE disrupts organelle acidification, leading to suppression of lysosomal catabolism, accumulation of dysfunctional lysosomes and compensatory lysosomal exocytosis. Restoring lysosomal pH rescues basal function in mRAVE-deficient cells but not the mTORC1-regulated increase in catabolic activity. Thus, mRAVE is an essential V-ATPase assembly factor that couples acidification to organelle function and nutrient signaling.

cell biology↗

bioRxiv2025

Dual Ribosome Profiling reveals metabolic limitations of cancer and stromal cells in thetumor microenvironment

Cancer cells, immune cells, and stromal cells within the tumor microenvironment (TME) collaboratively influence disease progression and therapeutic responses. The nutrient-limited conditions of the TME, particularly the scarcity of glucose, amino acids, and lipids, challenge cancer cell survival1-4. However, the metabolic constraints faced by immune and stromal cells in comparison to cancer cells, and how these limitations affect therapeutic outcomes, remain poorly understood. Here, we introduce Dual Ribosome Profiling (DualRP), a method that allows for simultaneous analysis of translation and identification of ribosome stalling, revealing amino acid shortages in different cell types within tumors. Using DualRP, we uncover that interactions between cancer cells and fibroblasts trigger an inflammatory response, mitigating amino acid limitations during glucose starvation. In immunocompetent mouse models, we observe that immune checkpoint blockade therapy induces serine and glycine restrictions specifically in T cells, but not in cancer cells. We further demonstrate that these amino acids are essential for optimal T cell function both in vitro and in vivo, highlighting their critical role in effective immunotherapy. Our findings show that therapeutic interventions create distinct metabolic demands across different tumor cell types, with nutrient availability significantly influencing the success of immunotherapy. DualRPs ability to explore cell type-specific metabolic vulnerabilities offers a promising tool for advancing our understanding of tumor biology and improving therapeutic strategies.

cancer biology↗

bioRxiv2019

CDK1 couples proliferation with protein synthesis

Cell proliferation exerts a high demand on protein synthesis, yet the mechanisms coupling the two processes are not fully understood. A kinase and phosphatase screen for activators of translation, based on the formation of stress granules in human cells, revealed cell cycle-associated kinases as major candidates. CDK1 was identified as a positive regulator of global translation, and cell synchronization experiments showed that this is an extra-mitotic function of CDK1. Dephosphorylation of eIF2 and S6K1 signaling were found to act downstream of CDK1. Moreover, Ribo-Seq analysis uncovered that CDK1 exerts a particularly strong effect on the translation of 5TOP mRNAs, which includes mRNAs encoding for ribosomal proteins and several translation factors. This effect requires the 5TOP mRNA-binding protein LARP1, concurrent to our finding that LARP1 phosphorylation is strongly dependent on CDK1. Taken together, our results show that CDK1 provides a direct means to couple cell proliferation with biosynthesis of the translation machinery and the rate of protein synthesis.

biochemistry↗