RESUMEN
Nutrient acquisition is essential for animal cells. ßγ-CAT is a pore-forming protein (PFP) and trefoil factor complex assembled under tight regulation identified in toad Bombina maxima. Here, we reported that B. maxima cells secreted ßγ-CAT under glucose, glutamine, and pyruvate deficiency to scavenge extracellular proteins for their nutrient supply and survival. AMPK signaling positively regulated the expression and secretion of ßγ-CAT. The PFP complex selectively bound extracellular proteins and promoted proteins uptake through endolysosomal pathways. Elevated intracellular amino acids, enhanced ATP production, and eventually prolonged cell survival were observed in the presence of ßγ-CAT and extracellular proteins. Liposome assays indicated that high concentration of ATP negatively regulated the opening of ßγ-CAT channels. Collectively, these results uncovered that ßγ-CAT is an essential element in cell nutrient scavenging under cell nutrient deficiency by driving vesicular uptake of extracellular proteins, providing a new paradigm for PFPs in cell nutrient acquisition and metabolic flexibility.
