Complex I Inhibition Redirects Autophagy from Bulk Turnover to Mitochondrial Clearance
- 1University of Kansas - Lawrence
Abstract
Mitochondria are both a major autophagic substrate and a principal source of signals that control autophagy, yet it is unknown whether a mitochondrial signal can specify which substrate the pathway degrades. Using metformin to inhibit Complex I in human cells, we find that autophagy is redirected rather than induced or suppressed. Inhibition shifts the NAD+/NADH ratio before perturbing the adenylate pool, separating the redox arm of the lesion from the bioenergetic arm. Single-molecule tracking of endogenous ATG13 and WIPI2 shows that initiation is preserved while WIPI2 tethering fails, generating short-lived, abortive autophagosomes; the ULK1 interactome concurrently disengages from cytoskeletal scaffolds, and Parkin-independent mitolysosomes accumulate. This response differs from mTORC1 inhibition and does not require PEN2, and AMPK is engaged non-canonically: 1/2 restrain ATG13 at initiation, while AMPK activation alone does not reproduce the WIPI2 phenotype. Occurring at therapeutic concentrations, these results identify the ULK1 complex as the step at which Complex I inhibition reassigns autophagic substrate.
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BibTeX
@misc{mutawi2026complex,
title = {{Complex I Inhibition Redirects Autophagy from Bulk Turnover to Mitochondrial Clearance}},
author = {T. M. Mutawi and S. R. Malvankar and A. Graziani and U. Shah and K. Nguyen and D. G. Broadbent and Z. Clark and M. J. Rekowski and S. M. Lunte and C. Barnaba},
howpublished = {bioRxiv},
year = {2026},
month = jun,
doi = {10.64898/2026.06.04.730191},
url = {https://www.biorxiv.org/content/10.64898/2026.06.04.730191v2},
note = {CC BY-NC},
}
RIS
TY - UNPB
TI - Complex I Inhibition Redirects Autophagy from Bulk Turnover to Mitochondrial Clearance
AU - T. M. Mutawi
AU - S. R. Malvankar
AU - A. Graziani
AU - U. Shah
AU - K. Nguyen
AU - D. G. Broadbent
AU - Z. Clark
AU - M. J. Rekowski
AU - S. M. Lunte
AU - C. Barnaba
PY - 2026
DA - 2026/06/04
PB - bioRxiv
DO - 10.64898/2026.06.04.730191
UR - https://www.biorxiv.org/content/10.64898/2026.06.04.730191v2
AB - Mitochondria are both a major autophagic substrate and a principal source of signals that control autophagy, yet it is unknown whether a mitochondrial signal can specify which substrate the pathway degrades. Using metformin to inhibit Complex I in human cells, we find that autophagy is redirected rather than induced or suppressed. Inhibition shifts the NAD+/NADH ratio before perturbing the adenylate pool, separating the redox arm of the lesion from the bioenergetic arm. Single-molecule tracking of endogenous ATG13 and WIPI2 shows that initiation is preserved while WIPI2 tethering fails, generating short-lived, abortive autophagosomes; the ULK1 interactome concurrently disengages from cytoskeletal scaffolds, and Parkin-independent mitolysosomes accumulate. This response differs from mTORC1 inhibition and does not require PEN2, and AMPK is engaged non-canonically: 1/2 restrain ATG13 at initiation, while AMPK activation alone does not reproduce the WIPI2 phenotype. Occurring at therapeutic concentrations, these results identify the ULK1 complex as the step at which Complex I inhibition reassigns autophagic substrate.
ER -