Proteomics analysis of starved cells revealed Annexin A1 as an important regulator of autophagic degradation

Macroautophagy is involved in the bulk degradation of long-lived cytosolic proteins and subcellular organelles, which is important for the survival of cells during starvation. To identify potential players of the autophagy process, we subjected HCT116 cells cultured in complete medium and in Earle’s balanced salt solution to proteomics analysis. In approximately 1500 protein spots detected, we characterized 52 unique proteins, whose expression levels were significantly changed following starvation. Notably, we found that Annexin A1 was significantly upregulated following starvation at both mRNA and protein levels. Inhibition of Annexin A1 expression with specific siRNA did not alter starvation-induced autophagy as measured by the level of lipidated LC3, but significantly reversed autophagy degradation as measured by the level of p62/SQSTM 1. Thus Annexin A1 seemed to be positively upregulated during starvation to promote autophagic degradation. Overall, the data presented in this study established a expression profile of the proteome in starved cells, which allowed the identification of proteins with potential significance in starvation-induced autophagy.

► Revealed the proteome changes in a colon cancer cell line, HCT116, following starvation.
► Defined that a unique proteins, Annexin A1, was increased at both transcriptional and translational level following starvation.
► Discovered that Annexin A1 participated in starvation-induced autophagic degradation, but not the initiation of autophagy. This is likely the first example of such a way to regulate autophagy process by an endogenous molecule.