Regulation of autophagy by extracellular matrix glycoproteins in HeLa cells

Macroautophagy is a major lysosomal degradation pathway for cellular components in eukaryotic cells. Baseline macroautophagy is important for quality control of the cytoplasm in order to avoid the accumulation of cytotoxic products. Its stimulation by various stressful situations, including nutrient starvation, is important in maintaining cell survival. Here we demonstrate that macroautophagy is regulated differently depending on whether HeLa cells adhere to collagen I or collagen IV, proteins typical of connective tissue and basal membrane, respectively. We observed that the basal levels of macroautophagy were higher in cells plated on collagen IV than in cells plated on collagen I or on uncoated substrate. However, the stimulation of macroautophagy by nutrient starvation, as reflected by the buildup of autophagosomes and the increase in the autophagic flux, was higher in cells plated on collagen I than in cells plated on collagen IV. These contrasting results were not due to differences in the starvatio...