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bioRxiv · 10.1101/2025.08.26.672461

CLIC-dependent internalization of caveolin-1 to lysosomal vacuoles in response to osmotic regulation

Wong, T. H.·Nagrath, A.·Lima, M. F.·Li, Y. L.·Nabit, I. R.
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Abstract

Originally thought to be a major endocytic portal, caveolae are now considered to function as a membrane buffer, whereby caveolae flattening protects the plasma membrane from rupture under mechanical stress, such as hypotonic shock. However, the fate of the caveolae coat protein caveolin-1 in response to hypotonic shock is not known. Here, we show that extended hypotonic shock induces ubiquitin-independent, CLIC-dependent endocytosis of caveolin-1 to large, intracellular, CD44-positive, pH-neutral lysosomal vacuoles negative for multivesicular body markers. Caveolin-1 recycles from these vacuoles to the plasma membrane upon return to isotonic conditions. Caveolin-1 internalizes not in response to initial cell expansion upon hypotonic shock but rather subsequent reduction of cell volume, and also in low-tension cells grown on reduced stiffness hydrogels. Upon hypertonic shock, caveolin-1 internalization occurs selectively in PC3 cells, lacking cavin-1, required for caveolae formation, and is inhibited upon cavin-1 reintroduction. CLIC endocytosis of non-caveolar caveolin-1 to neutral pH lysosomal vacuoles in response to osmotic regulation defines a novel recycling pathway enabling caveolae membrane buffering.

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Wong, T. H., Nagrath, A., Lima, M. F., Li, Y. L., Nabit, I. R.. 2025-08-29. CLIC-dependent internalization of caveolin-1 to lysosomal vacuoles in response to osmotic regulation. https://doi.org/10.1101/2025.08.26.672461

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