Biology subjects

Koehler, C. M.

Publications and source records attributed to Koehler, C. M..

3 recordsLinked to original sources

bioRxiv2026

Dynamin-2 promotes Atg9A retrieval from phagophores during autophagy.

Autophagy involves the rapid growth of phagophores through membrane addition. This growth is triggered by vesicles containing the Atg9A protein. However, Atg9A is not incorporated into mature autophagosomes. We now demonstrate that Dynamin-2 (Dnm2) colocalizes with the BAR domain protein Endophilin-B1 (EndoB1/Bif-1/SH3GLB1) and other autophagy proteins when autophagy is induced. Our data suggest that Atg9A is retrieved from phagophores via fission, with Dnm2 acting as the membrane scission protein. Blocking Atg9A recycling, either by mutating Dnm2, using RNA interference, or applying chemical inhibitors, results in Atg9A remaining in autophagosomes and being degraded during autophagy. Overall, these findings provide new insights into the roles of membrane-scission proteins in autophagy.

cell biology↗

bioRxiv2024

Mfn2 induces NCLX-mediated calcium release from mitochondria.

Mfn2 is a mitochondrial outer-membrane fusion protein that also functions as a tether between mitochondria and the ER. Here, we identify a previously unrecognized role for Mfn2 in promoting mitochondrial Ca2+ release via the Na+/Ca2+ exchanger NCLX. This function was uncovered through studies with the fungal toxin phomoxanthone A (PXA), which induces NCLX-dependent Ca2+ release by directly targeting Mfn2. Mfn2-dependent Ca2+ release through NCLX is similarly triggered by ROS in respiring cells treated with oligomycin or mitoPQ. ROS enhances Ca2+ release by strengthening the interaction between Mfn2 and NCLX, an interaction that also requires the mitochondrial outer-membrane protein SLC25A46. Together, these proteins coordinate mitochondrial fission and Ca2+ release to initiate mitophagy. The antioxidant N-acetylcysteine blocks ROS-induced mitochondrial fission, but inhibition of Ca2+ release with the NCLX inhibitor CGP37157 does not, indicating that ROS-driven fission is independent of Ca2+ release. In contrast, Ca2+ release is required for efficient mitophagy, as NCLX inhibition arrests this process at a later stage. We further show that Ca2+ promotes mitophagy through NEDD4-1, which is a Ca2+-responsive E3 ubiquitin ligase. Together, these findings connect mitochondrial ROS production to Ca2+ signaling, mitochondrial remodeling, and mitophagy, providing new insight into how mitochondrial dysfunction may contribute to neurodegenerative and metabolic disease.

cell biology↗

bioRxiv2018

Dynamin-2 facilitates Atg9 recycling from nascent autophagosomes

Autophagy involves rapid growth of phagophores through membrane addition. Newly added membranes are derived from other organelles through vesicles carrying the Atg9 protein. Membrane is delivered by fusing these vesicles with the phagophores. Atg9 is, nevertheless, not incorporated in autophagosomes. We now show that this protein is retrieved from phagophores by fission utilizing Dynamin-2 (Dnm2) as the membrane scission protein. Blocking Atg9 recycling by interfering with Dnm2 helps retain Atg9 in autophagosomes and degrades this protein by autophagy. Dnm2 colocalizes with the BAR domain protein Endophilin-B1 (EndoB1/Bif-1) when autophagy is induced, consistent with transient interactions during Atg9 retrieval. EndoB1 and Dnm2 also control the downstream fusion of phagophores to late endosomes, thus ensuring the completion of phagophores before proceeding to the next stage in the autophagy process. These data provide novel insights into the roles of membrane scission proteins during autophagy.

cell biology↗