The rapidly expanding role of LC3-interacting regions in autophagy
Brian J. North, Dorotea Fracchiolla, Michael J. Ragusa, Sascha Martens, Christopher J. Shoemaker
Abstract
LC3-interacting regions (LIRs), or Atg8-interacting motifs (AIMs), are short linear motifs found in unstructured loops or intrinsically disordered regions of many autophagy-related proteins. LIRs were initially identified for their role in binding to Atg8 family proteins on autophagosomal membranes. However, emerging evidence suggests that LIRs and their surrounding residues mediate interactions with a wide array of proteins beyond Atg8s. This broadens the biological significance of LIRs in autophagy, rendering them an organizing principle of the autophagy machinery. In this perspective, we explore recent advances highlighting the multifunctional roles of LIRs, including their capacity to mediate binding with diverse factors. We discuss insights into the mechanisms underlying LIR-mediated interactions and propose an updated model to explain Atg8 diversification in higher eukaryotes. We conclude by addressing key challenges and outlining future directions for understanding LIR biology and its broader implications for cellular homeostasis.