A lysosome membrane regeneration pathway depends on TBC1D15 and autophagic lysosomal reformation proteins.

Abstract

Acute lysosomal membrane damage reduces the cellular population of functional lysosomes. However, these damaged lysosomes have a remarkable recovery potential independent of lysosomal biogenesis and remain unaffected in cells depleted in TFEB and TFE3. We combined proximity-labelling-based proteomics, biochemistry and high-resolution microscopy to unravel a lysosomal membrane regeneration pathway that depends on ATG8, the lysosomal membrane protein LIMP2, the RAB7 GTPase-activating protein TBC1D15 and proteins required for autophagic lysosomal reformation, including dynamin-2, kinesin-5B and clathrin. Following lysosomal damage, LIMP2 acts as a lysophagy receptor to bind ATG8, which in turn recruits TBC1D15 to damaged membranes. TBC1D15 interacts with ATG8 proteins on damaged lysosomes and provides a scaffold to assemble and stabilize the autophagic lysosomal reformation machinery. This potentiates the formation of lysosomal tubules and subsequent dynamin-2-dependent scission. TBC1D15-mediated lysosome regeneration was also observed in a cell culture model of oxalate nephropathy.