Alf Håkon Lohsen Lystad

• Dahl, Anette Kathinka; Mann, Daniel; Lystad, Alf Håkon Lohsen; Sachse, Carsten; Simonsen, Anne Gjøen & Pankiv, Serhiy (2026). Characterizing the membrane recruitment domain of BDCPs and its role in gray platelet syndrome. Journal of Cell Biology. ISSN 0021-9525. 225(10). doi: 10.1083/jcb.202510098. Fulltekst i vitenarkiv
• Lystad, Alf Håkon Lohsen (2025). V-ATPase assembly at leaky lysosomes. Nature Structural & Molecular Biology. ISSN 1545-9993. 32(10), s. 1862–1864. doi: 10.1038/s41594-025-01612-7. Fulltekst i vitenarkiv
• Kaur, Namrita; Carlsson, Sven R. & Lystad, Alf Håkon Lohsen (2025). Lysosome-associated CASM: from upstream triggers to downstream effector mechanisms. Frontiers in Cell and Developmental Biology. 13. doi: 10.3389/fcell.2025.1559125. Fulltekst i vitenarkiv Vis sammendrag

  Lysosomes are dynamic organelles critical for cellular degradation and signaling, safeguarded by a limiting membrane that prevents leakage of harmful contents into the cytoplasm. Upon lysosomal damage, cells deploy defensive mechanisms, including a key process called CASM (conjugation of ATG8 to single membranes), which lipidates ATG8 proteins onto the limiting membrane to support protective pathways. CASM operates through two pathways: VAIL, induced by lysosomal pH changes via V-ATPase and ATG16L1, and STIL, triggered by sphingomyelin exposure and mediated by TECPR1. This review examines CASM’s role in lysosomal damage responses, exploring the mechanisms of damaging agents, distinctions between VAIL and STIL, and the downstream effects of decorating lysosomes with ATG8, including effector recruitment for membrane repair or removal.

• Duran, Jacob; Salinas, Jay E; Wheaton, Rui ping; Poolsup, Suttinee; Allers, Lee & Rosas-Lemus, Monica [Vis alle 17 forfattere av denne artikkelen] (2024). Calcium signaling from damaged lysosomes induces cytoprotective stress granules. EMBO Journal. ISSN 0261-4189. 43, s. 6410–6443. doi: 10.1038/s44318-024-00292-1. Fulltekst i vitenarkiv Vis sammendrag

  Lysosomal damage induces stress granule (SG) formation. However, the importance of SGs in determining cell fate and the precise mechanisms that mediate SG formation in response to lysosomal damage remain unclear. Here, we describe a novel calcium-dependent pathway controlling SG formation, which promotes cell survival during lysosomal damage. Mechanistically, the calcium-activated protein ALIX transduces lysosomal damage signals to SG formation by controlling eIF2α phosphorylation after sensing calcium leakage. ALIX enhances eIF2α phosphorylation by promoting the association between PKR and its activator PACT, with galectin-3 inhibiting this interaction; these regulatory events occur on damaged lysosomes. We further find that SG formation plays a crucial role in promoting cell survival upon lysosomal damage caused by factors such as SARS-CoV-2ORF3a, adenovirus, malarial pigment, proteopathic tau, or environmental hazards. Collectively, these data provide insights into the mechanism of SG formation upon lysosomal damage and implicate it in diseases associated with damaged lysosomes and SGs.

• Kaur, Namrita; Carlsson, Sven R & Lystad, Alf Håkon Lohsen (2023). The separate axes of TECPR1 and ATG16L1 in CASM. Autophagy. ISSN 1554-8627. s. 1–2. doi: 10.1080/15548627.2023.2255462. Fulltekst i vitenarkiv Vis sammendrag

  Conjugation of ATG8 to single membranes (CASM) is a fundamental cellular process that entails the conjugation of mammalian Atg8 homologs, here referred to as ATG8, to phosphatidylethanolamine (PE) and phosphatidylserine (PS) on endolysosomal compartments. Our current research, together with recent reports from the Randow, Wu, and Wileman labs, has uncovered yet another layer to this process. We discovered that, in addition to ATG16L1-containing complexes, TECPR1 (tectonin beta-propeller repeat containing 1)-containing ATG12–ATG5 E3 complexes can facilitate CASM, thereby providing a broader understanding of this pathway.

• Kaur, Namrita; Ballina, Laura R de la; Haukaas, Håvard Styrkestad; Torgersen, Maria Lyngaas; Radulovic, Maja & Munson, Michael J [Vis alle 11 forfattere av denne artikkelen] (2023). TECPR1 is activated by damage-induced sphingomyelin exposure to mediate noncanonical autophagy. EMBO Journal. ISSN 0261-4189. 42(17), s. 1–19. doi: 10.15252/embj.2022113105. Fulltekst i vitenarkiv Vis sammendrag

  Abstract Cells use noncanonical autophagy, also called conjugation of ATG8 to single membranes (CASM), to label damaged intracellular compartments with ubiquitin‐like ATG8 family proteins in order to signal danger caused by pathogens or toxic compounds. CASM relies on E3 complexes to sense membrane damage, but so far, only the mechanism to activate ATG16L1‐containing E3 complexes, associated with proton gradient loss, has been described. Here, we show that TECPR1‐containing E3 complexes are key mediators of CASM in cells treated with a variety of pharmacological drugs, including clinically relevant nanoparticles, transfection reagents, antihistamines, lysosomotropic compounds, and detergents. Interestingly, TECPR1 retains E3 activity when ATG16L1 CASM activity is obstructed by the Salmonella Typhimurium pathogenicity factor SopF. Mechanistically, TECPR1 is recruited by damage‐induced sphingomyelin (SM) exposure using two DysF domains, resulting in its activation and ATG8 lipidation. In vitro assays using purified human TECPR1‐ATG5‐ATG12 complex show direct activation of its E3 activity by SM, whereas SM has no effect on ATG16L1‐ATG5‐ATG12. We conclude that TECPR1 is a key activator of CASM downstream of SM exposure.

• Radulovic, Maja; Wenzel, Eva; Gilani, Sania; Holland, Lya KK; Lystad, Alf Håkon Lohsen & Phuyal, Santosh [Vis alle 12 forfattere av denne artikkelen] (2022). Cholesterol transfer via endoplasmic reticulum contacts mediates lysosome damage repair. EMBO Journal. ISSN 0261-4189. 41:e112677, s. 1–18. doi: 10.15252/embj.2022112677. Fulltekst i vitenarkiv Vis sammendrag

  Lysosome integrity is essential for cell viability, and lesions in lysosome membranes are repaired by the ESCRT machinery. Here, we describe an additional mechanism for lysosome repair that is activated independently of ESCRT recruitment. Lipidomic analyses showed increases in lysosomal phosphatidylserine and cholesterol after damage. Electron microscopy demonstrated that lysosomal membrane damage is rapidly followed by the formation of contacts with the endoplasmic reticulum (ER), which depends on the ER proteins VAPA/B. The cholesterol-binding protein ORP1L was recruited to damaged lysosomes, accompanied by cholesterol accumulation by a mechanism that required VAP–ORP1L interactions. The PtdIns 4-kinase PI4K2A rapidly produced PtdIns4P on lysosomes upon damage, and knockout of PI4K2A inhibited damage-induced accumulation of ORP1L and cholesterol and led to the failure of lysosomal membrane repair. The cholesterol–PtdIns4P transporter OSBP was also recruited upon damage, and its depletion caused lysosomal accumulation of PtdIns4P and resulted in cell death. We conclude that ER contacts are activated on damaged lysosomes in parallel to ESCRTs to provide lipids for membrane repair, and that PtdIns4P generation and removal are central in this response.

• Søreng, Kristiane; Pankiv, Serhiy; Bergsmark, Camilla; Haugsten, Ellen Margrethe; Dahl, Anette Kathinka & Ballina, Laura R de la [Vis alle 9 forfattere av denne artikkelen] (2022). ALFY localizes to early endosomes and cellular protrusions to facilitate directional cell migration. Journal of Cell Science. ISSN 0021-9533. 135(4). doi: 10.1242/jcs.259138. Fulltekst i vitenarkiv Vis sammendrag

  ABSTRACT Cell migration is a complex process underlying physiological and pathological processes such as brain development and cancer metastasis. The autophagy-linked FYVE protein (ALFY; also known as WDFY3), an autophagy adaptor protein known to promote clearance of protein aggregates, has been implicated in brain development and neural migration during cerebral cortical neurogenesis in mice. However, a specific role of ALFY in cell motility and extracellular matrix adhesion during migration has not been investigated. Here, we reveal a novel role for ALFY in the endocytic pathway and in cell migration. We show that ALFY localizes to RAB5- and EEA1-positive early endosomes in a PtdIns(3)P-dependent manner and is highly enriched in cellular protrusions at the leading and lagging edge of migrating cells. We find that cells lacking ALFY have reduced attachment and altered protein levels and glycosylation of integrins, resulting in the inability to form a proper leading edge and loss of directional cell motility.

• Xu, Jing; Yang, Kevin C; Go, Nancy Erro; Colborne, Shane; Ho, Cally J & Hosseini-Beheshti, Elham [Vis alle 11 forfattere av denne artikkelen] (2022). Chloroquine treatment induces secretion of autophagy-related proteins and inclusion of Atg8-family proteins in distinct extracellular vesicle populations. Autophagy. ISSN 1554-8627. 18(11), s. 2547–2560. doi: 10.1080/15548627.2022.2039535. Fulltekst i vitenarkiv Vis sammendrag

  Chloroquine (CQ), a lysosomotropic agent, is commonly used to inhibit lysosomal degradation and macroautophagy/autophagy. Here we investigated the cell-extrinsic effects of CQ on secretion. We showed that lysosomal and autophagy inhibition by CQ altered the secretome, and induced the release of Atg8 orthologs and autophagy receptors. Atg8-family proteins, in particular, were secreted inside small extracellular vesicles (sEVs) in a lipidation-dependent manner. CQ treatment enhanced the release of Atg8-family proteins inside sEVs. Using full-length ATG16L1 and an ATG16L1 mutant that enables Atg8-family protein lipidation on double but not on single membranes, we demonstrated that LC3B is released in two distinct sEV populations: one enriched with SDCBP/Syntenin-1, CD63, and endosomal lipidated LC3B, and another that contains LC3B but is not enriched with SDCBP/Syntenin-1 or CD63, and which our data supports as originating from a double-membrane source. Our findings underscore the context-dependency of sEV heterogeneity and composition, and illustrate the integration of autophagy and sEV composition in response to lysosomal inhibition.

• Durgan, Joanne; Lystad, Alf Håkon Lohsen; Sloan, Katherine; Carlsson, Sven R.; Wilson, Michael I. & Marcassa, Elena [Vis alle 14 forfattere av denne artikkelen] (2021). Non-canonical autophagy drives alternative ATG8 conjugation to phosphatidylserine. Molecular Cell. ISSN 1097-2765. 81(9), s. 2031–2040.e8. doi: 10.1016/j.molcel.2021.03.020. Fulltekst i vitenarkiv Vis sammendrag

  Autophagy is a fundamental catabolic process that uses a unique post-translational modification, the conjugation of ATG8 protein to phosphatidylethanolamine (PE). ATG8 lipidation also occurs during non-canonical autophagy, a parallel pathway involving conjugation of ATG8 to single membranes (CASM) at endolysosomal compartments, with key functions in immunity, vision, and neurobiology. It is widely assumed that CASM involves the same conjugation of ATG8 to PE, but this has not been formally tested. Here, we discover that all ATG8s can also undergo alternative lipidation to phosphatidylserine (PS) during CASM, induced pharmacologically, by LC3-associated phagocytosis or influenza A virus infection, in mammalian cells. Importantly, ATG8-PS and ATG8-PE adducts are differentially delipidated by the ATG4 family and bear different cellular dynamics, indicating significant molecular distinctions. These results provide important insights into autophagy signaling, revealing an alternative form of the hallmark ATG8 lipidation event. Furthermore, ATG8-PS provides a specific “molecular signature” for the non-canonical autophagy pathway.

• Munson, Michael Joseph; Mathai, Benan J.; Ng, Matthew; Moncho, Laura Cristina Trachsel; Ballina, Laura R de la & Schultz, Sebastian W. [Vis alle 13 forfattere av denne artikkelen] (2021). GAK and PRKCD are positive regulators of PRKN-independent mitophagy. Nature Communications. 12(1). doi: 10.1038/s41467-021-26331-7. Fulltekst i vitenarkiv Vis sammendrag

  The mechanisms involved in programmed or damage-induced removal of mitochondria by mitophagy remains elusive. Here, we have screened for regulators of PRKN-independent mitophagy using an siRNA library targeting 197 proteins containing lipid interacting domains. We identify Cyclin G-associated kinase (GAK) and Protein Kinase C Delta (PRKCD) as regulators of PRKN-independent mitophagy, with both being dispensable for PRKN- dependent mitophagy and starvation-induced autophagy. We demonstrate that the kinase activity of both GAK and PRKCD are required for efficient mitophagy in vitro, that PRKCD is present on mitochondria, and that PRKCD facilitates recruitment of ULK1/ATG13 to early autophagic structures. Importantly, we demonstrate in vivo relevance for both kinases in the regulation of basal mitophagy. Knockdown of GAK homologue (gakh-1) in C. elegans or knockout of PRKCD homologues in zebrafish led to significant inhibition of basal mitophagy, highlighting the evolutionary relevance of these kinases in mitophagy regulation.

• Giovannucci, Tatiana A.; Salomons, Florian A.; Stoy, Henriette; Herzog, Laura K.; Xu, Shanshan & Qian, Weixing [Vis alle 15 forfattere av denne artikkelen] (2021). Identification of a novel compound that simultaneously impairs the ubiquitin-proteasome system and autophagy. Autophagy. ISSN 1554-8627. doi: 10.1080/15548627.2021.1988359. Fulltekst i vitenarkiv Vis sammendrag

  The ubiquitin-proteasome system (UPS) and macroautophagy/autophagy are the main proteolytic systems in eukaryotic cells for preserving protein homeostasis, i.e., proteostasis. By facilitating the timely destruction of aberrant proteins, these complementary pathways keep the intracellular environment free of inherently toxic protein aggregates. Chemical interference with the UPS or autophagy has emerged as a viable strategy for therapeutically targeting malignant cells which, owing to their hyperactive state, heavily rely on the sanitizing activity of these proteolytic systems. Here, we report on the discovery of CBK79, a novel compound that impairs both protein degradation by the UPS and autophagy. While CBK79 was identified in a high-content screen for drug-like molecules that inhibit the UPS, subsequent analysis revealed that this compound also compromises autophagic degradation of long-lived proteins. We show that CBK79 induces non-canonical lipidation of MAP1LC3B/LC3B (microtubule-associated protein 1 light chain 3 beta) that requires ATG16L1 but is independent of the ULK1 (unc-51 like autophagy activating kinase 1) and class III phosphatidylinositol 3-kinase (PtdIns3K) complexes. Thermal preconditioning of cells prevented CBK79-induced UPS impairment but failed to restore autophagy, indicating that activation of stress responses does not allow cells to bypass the inhibitory effect of CBK79 on autophagy. The identification of a small molecule that simultaneously impairs the two main proteolytic systems for protein quality control provides a starting point for the development of a novel class of proteostasis-targeting drugs.

• Kumar, Suresh; Javed, Ruheena; Mudd, Michal H.; Pallikkuth, Sandeep; Lidke, Keith A. & Jain, Ashish [Vis alle 22 forfattere av denne artikkelen] (2021). Mammalian hybrid pre-autophagosomal structure HyPAS generates autophagosomes. Cell. ISSN 0092-8674. 184(24), s. 5950–5969. doi: 10.1016/j.cell.2021.10.017. Fulltekst i vitenarkiv Vis sammendrag

  The biogenesis of mammalian autophagosomes remains to be fully defined. Here, we used cellular and in vitro membrane fusion analyses to show that autophagosomes are formed from a hitherto unappreciated hybrid membrane compartment. The autophagic precursors emerge through fusion of FIP200 vesicles, derived from the cis-Golgi, with endosomally derived ATG16L1 membranes to generate a hybrid pre-autophagosomal structure, HyPAS. A previously unrecognized apparatus defined here controls HyPAS biogenesis and mammalian autophagosomal precursor membranes. HyPAS can be modulated by pharmacological agents whereas its formation is inhibited upon severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection or by expression of SARS-CoV-2 nsp6. These findings reveal the origin of mammalian autophagosomal membranes, which emerge via convergence of secretory and endosomal pathways, and show that this process is targeted by microbial factors such as coronaviral membrane-modulating proteins

• Klionsky, Daniel J.; Abdel-Aziz, Amal Kamal; Abdelfatah, Sara; Abdellatif, Mahmoud Khaled; Abdoli, Asghar & Abudu, Yakubu Princely [Vis alle 50 forfattere av denne artikkelen] (2021). Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition). Autophagy. ISSN 1554-8627. 17(1), s. 1–382. doi: https:/www.tandfonline.com/doi/full/10.1080/15548627.2020.1797280. Fulltekst i vitenarkiv
• Corkery, Dale P.; Nadeem, Aftab; Aung, Kyaw Min; Hassan, Ahmed; Liu, Tao & Cervantes-Rivera, Ramón [Vis alle 14 forfattere av denne artikkelen] (2021). Vibrio cholerae cytotoxin MakA induces noncanonical autophagy resulting in the spatial inhibition of canonical autophagy. Journal of Cell Science. ISSN 0021-9533. 134(5). doi: 10.1242/jcs.252015. Fulltekst i vitenarkiv
• Hamaoui, Daniel; Cossé, Mathilde M.; Mohan, Jagan; Lystad, Alf Håkon; Wollert, Thomas & Subtil, Agathe (2020). The Chlamydia effector CT622/TaiP targets a nonautophagy related function of ATG16L1. Proceedings of the National Academy of Sciences of the United States of America (PNAS). ISSN 0027-8424. 117(43), s. 26784–26794. doi: 10.1073/pnas.2005389117. Fulltekst i vitenarkiv Vis sammendrag

  The obligate intracellular bacteria Chlamydia trachomatis, the causative agent of trachoma and sexually transmitted diseases, multiply in a vacuolar compartment, the inclusion. From this niche, they secrete “effector” proteins, that modify cellular activities to enable bacterial survival and proliferation. Here, we show that the host autophagy-related protein 16-1 (ATG16L1) restricts inclusion growth and that this effect is counteracted by the secretion of the bacterial effector CT622/TaiP (translocated ATG16L1 interacting protein). ATG16L1 is mostly known for its role in the lipidation of the human homologs of ATG8 (i.e., LC3 and homologs) on double membranes during autophagy as well as on single membranes during LC3-associated phagocytosis and other LC3-lipidation events. Unexpectedly, the LC3-lipidation-related functions of ATG16L1 are not required for restricting inclusion development. We show that the carboxyl-terminal domain of TaiP exposes a mimic of an eukaryotic ATG16L1-binding motif that binds to ATG16L1’s WD40 domain. By doing so, TaiP prevents ATG16L1 interaction with the integral membrane protein TMEM59 and allows the rerouting of Rab6-positive compartments toward the inclusion. The discovery that one bacterial effector evolved to target ATG16L1’s engagement in intracellular traffic rather than in LC3 lipidation brings this “secondary” activity of ATG16L1 in full light and emphasizes its importance for maintaining host cell homeostasis.

• Melia, Thomas; Lystad, Alf Håkon & Simonsen, Anne (2020). Autophagosome biogenesis: From membrane growth to closure. Journal of Cell Biology. ISSN 0021-9525. 219(6). doi: 10.1083/jcb.202002085. Fulltekst i vitenarkiv Vis sammendrag

  Autophagosome biogenesis involves de novo formation of a membrane that elongates to sequester cytoplasmic cargo and closes to form a double-membrane vesicle (an autophagosome). This process has remained enigmatic since its initial discovery >50 yr ago, but our understanding of the mechanisms involved in autophagosome biogenesis has increased substantially during the last 20 yr. Several key questions do remain open, however, including, What determines the site of autophagosome nucleation? What is the origin and lipid composition of the autophagosome membrane? How is cargo sequestration regulated under nonselective and selective types of autophagy? This review provides key insight into the core molecular mechanisms underlying autophagosome biogenesis, with a specific emphasis on membrane modeling events, and highlights recent conceptual advances in the field.

• Lystad, Alf Håkon; Carlsson, Sven R. & Simonsen, Anne (2019). Toward the function of mammalian ATG12-ATG5-ATG16L1 complex in autophagy and related processes. Autophagy. ISSN 1554-8627. 15(8), s. 1485–1486. doi: 10.1080/15548627.2019.1618100. Fulltekst i vitenarkiv Vis sammendrag

  The machinery that decorates autophagic membranes with lipid-conjugated LC3/GABARAP is not yet fully understood. We recently reported the purification of the full-length ATG12–ATG5-ATG16L1 complex, and in reconstitution experiments with purified ATG7, ATG3, and LC3/GABARAP in vitro, together with rescue experiments in knockout cells, important aspects of the complete lipidation reaction were revealed. Hitherto unobserved membrane-binding regions in ATG16L1 were found, contributing to properties that explain the crucial role of this protein in membrane targeting and LC3/GABARAP lipidation in macroautophagy/autophagy and other related processes.

• Lystad, Alf Håkon; Carlsson, Sven R; Ballina, Laura Rodriguez de la; Kauffman, Karlina J; Nag, Shanta & Yoshimori, Tamotsu [Vis alle 8 forfattere av denne artikkelen] (2019). Distinct functions of ATG16L1 isoforms in membrane binding and LC3B lipidation in autophagy-related processes. Nature Cell Biology. ISSN 1465-7392. 21(3), s. 372–383. doi: 10.1038/s41556-019-0274-9. Fulltekst i vitenarkiv Vis sammendrag

  Covalent modification of LC3 and GABARAP proteins to phosphatidylethanolamine in the double-membrane phagophore is a key event in the early phase of macroautophagy, but can also occur on single-membrane structures. In both cases this involves transfer of LC3/GABARAP from ATG3 to phosphatidylethanolamine at the target membrane. Here we have purified the full-length human ATG12-5–ATG16L1 complex and show its essential role in LC3B/GABARAP lipidation in vitro. We have identified two functionally distinct membrane-binding regions in ATG16L1. An N-terminal membrane-binding amphipathic helix is required for LC3B lipidation under all conditions tested. By contrast, the C-terminal membrane-binding region is dispensable for canonical autophagy but essential for VPS34-independent LC3B lipidation at perturbed endosomes. We further show that the ATG16L1 C-terminus can compensate for WIPI2 depletion to sustain lipidation during starvation. This C-terminal membrane-binding region is present only in the β-isoform of ATG16L1, showing that ATG16L1 isoforms mechanistically distinguish between different LC3B lipidation mechanisms under different cellular conditions.

• Abudu, Yakubu Princely; Pankiv, Serhiy; Mathai, Benan John; Lystad, Alf Håkon; Bindesbøll, Christian & Brenne, Hanne Britt [Vis alle 14 forfattere av denne artikkelen] (2019). NIPSNAP1 and NIPSNAP2 act as “eat-me signal” for mitophagy. Developmental Cell. ISSN 1534-5807. 49(4), s. 509–525.e12. doi: 10.1016/j.devcel.2019.03.013. Fulltekst i vitenarkiv Vis sammendrag

  The clearance of damaged or dysfunctional mitochondria by selective autophagy (mitophagy) is important for cellular homeostasis and prevention of disease. Our understanding of the mitochondrial signals that trigger their recognition and targeting by mitophagy is limited. Here, we show that the mitochondrial matrix proteins 4-Nitrophenylphosphatase domain and non-neuronal SNAP25-like protein homolog 1 (NIPSNAP1) and NIPSNAP2 accumulate on the mitochondria surface upon mitochondrial depolarization. There, they recruit proteins involved in selective autophagy, including autophagy receptors and ATG8 proteins, thereby functioning as an “eat me” signal for mitophagy. NIPSNAP1 and NIPSNAP2 have a redundant function in mitophagy and are predominantly expressed in different tissues. Zebrafish lacking a functional Nipsnap1 display reduced mitophagy in the brain and parkinsonian phenotypes, including loss of tyrosine hydroxylase (Th1)-positive dopaminergic (DA) neurons, reduced motor activity, and increased oxidative stress.

• Herhaus, Lina; Bhaskara, Ramachandra M; Lystad, Alf Håkon; Gestal-Mato, Uxia; Covarrubias-Pinto, Adriana & Bonn, Florian [Vis alle 9 forfattere av denne artikkelen] (2019). TBK1-mediated phosphorylation of LC3C and GABARAP-L2 controls autophagosome shedding by ATG4 protease. EMBO Reports. ISSN 1469-221X. doi: 10.15252/embr.201948317. Fulltekst i vitenarkiv Vis sammendrag

  Autophagy is a highly conserved catabolic process through which defective or otherwise harmful cellular components are targeted for degradation via the lysosomal route. Regulatory pathways, involving post‐translational modifications such as phosphorylation, play a critical role in controlling this tightly orchestrated process. Here, we demonstrate that TBK1 regulates autophagy by phosphorylating autophagy modifiers LC3C and GABARAP‐L2 on surface‐exposed serine residues (LC3C S93 and S96; GABARAP‐L2 S87 and S88). This phosphorylation event impedes their binding to the processing enzyme ATG4 by destabilizing the complex. Phosphorylated LC3C/GABARAP‐L2 cannot be removed from liposomes by ATG4 and are thus protected from ATG4‐mediated premature removal from nascent autophagosomes. This ensures a steady coat of lipidated LC3C/GABARAP‐L2 throughout the early steps in autophagosome formation and aids in maintaining a unidirectional flow of the autophagosome to the lysosome. Taken together, we present a new regulatory mechanism of autophagy, which influences the conjugation and de‐conjugation of LC3C and GABARAP‐L2 to autophagosomes by TBK1‐mediated phosphorylation.

• Lystad, Alf Håkon & Simonsen, Anne (2019). Mechanisms and Pathophysiological Roles of the ATG8 Conjugation Machinery. Cells. 8(9), s. 973–973. doi: 10.3390/cells8090973. Fulltekst i vitenarkiv Vis sammendrag

  Since their initial discovery around two decades ago, the yeast autophagy-related (Atg)8 protein and its mammalian homologues of the light chain 3 (LC3) and γ-aminobutyric acid receptor associated proteins (GABARAP) families have been key for the tremendous expansion of our knowledge about autophagy, a process in which cytoplasmic material become targeted for lysosomal degradation. These proteins are ubiquitin-like proteins that become directly conjugated to a lipid in the autophagy membrane upon induction of autophagy, thus providing a marker of the pathway, allowing studies of autophagosome biogenesis and maturation. Moreover, the ATG8 proteins function to recruit components of the core autophagy machinery as well as cargo for selective degradation. Importantly, comprehensive structural and biochemical in vitro studies of the machinery required for ATG8 protein lipidation, as well as their genetic manipulation in various model organisms, have provided novel insight into the molecular mechanisms and pathophysiological roles of the mATG8 proteins. Recently, it has become evident that the ATG8 proteins and their conjugation machinery are also involved in intracellular pathways and processes not related to autophagy. This review focuses on the molecular functions of ATG8 proteins and their conjugation machinery in autophagy and other pathways, as well as their links to disease.

• Herzog, Laura K; Kevei, Eva; Marchante, Ricardo; Botther, Claudia; Bindesbøll, Christian & Lystad, Alf Håkon [Vis alle 12 forfattere av denne artikkelen] (2019). The Machado-Joseph disease deubiquitylase ataxin-3 interacts with LC3C/GABARAP and promotes autophagy. Aging Cell. ISSN 1474-9718. doi: 10.1111/acel.13051. Fulltekst i vitenarkiv Vis sammendrag

  The pathology of spinocerebellar ataxia type 3, also known as Machado‐Joseph disease, is triggered by aggregation of toxic ataxin‐3 (ATXN3) variants containing expanded polyglutamine repeats. The physiological role of this deubiquitylase, however, remains largely unclear. Our recent work showed that ATX‐3, the nematode orthologue of ATXN3, together with the ubiquitin‐directed segregase CDC‐48, regulates longevity in Caenorhabditis elegans. Here, we demonstrate that the long‐lived cdc‐48.1; atx‐3 double mutant displays reduced viability under prolonged starvation conditions that can be attributed to the loss of catalytically active ATX‐3. Reducing the levels of the autophagy protein BEC‐1 sensitized worms to the effect of ATX‐3 deficiency, suggesting a role of ATX‐3 in autophagy. In support of this conclusion, the depletion of ATXN3 in human cells caused a reduction in autophagosomal degradation of proteins. Surprisingly, reduced degradation in ATXN3‐depleted cells coincided with an increase in the number of autophagosomes while levels of lipidated LC3 remained unaffected. We identified two conserved LIR domains in the catalytic Josephin domain of ATXN3 that directly interacted with the autophagy adaptors LC3C and GABARAP in vitro. While ATXN3 localized to early autophagosomes, it was not subject to lysosomal degradation, suggesting a transient regulatory interaction early in the autophagic pathway. We propose that the deubiquitylase ATX‐3/ATXN3 stimulates autophagic degradation by preventing superfluous initiation of autophagosomes, thereby promoting an efficient autophagic flux important to survive starvation.

• Kauffman, Karlina J; Yu, Shenliang; Jin, Jiaxin; Mugo, Brian; Nguyen, Nathan & O'Brien, Aidan [Vis alle 9 forfattere av denne artikkelen] (2018). Delipidation of mammalian Atg8-family proteins by each of the four ATG4 proteases. Autophagy. ISSN 1554-8627. 14(6), s. 992–1010. doi: 10.1080/15548627.2018.1437341. Fulltekst i vitenarkiv
• Holland, Petter; Knævelsrud, Helene; Søreng, Kristiane; Mathai, Benan John; Lystad, Alf Håkon & Pankiv, Serhiy [Vis alle 16 forfattere av denne artikkelen] (2016). HS1BP3 negatively regulates autophagy by modulation of phosphatidic acid levels. Nature Communications. 7. doi: 10.1038/ncomms13889. Fulltekst i vitenarkiv Vis sammendrag

  A fundamental question is how autophagosome formation is regulated. Here we show that the PX domain protein HS1BP3 is a negative regulator of autophagosome formation. HS1BP3 depletion increased the formation of LC3-positive autophagosomes and degradation of cargo both in human cell culture and in zebrafish. HS1BP3 is localized to ATG16L1- and ATG9-positive autophagosome precursors and we show that HS1BP3 binds phosphatidic acid (PA) through its PX domain. Furthermore, we find the total PA content of cells to be significantly upregulated in the absence of HS1BP3, as a result of increased activity of the PA-producing enzyme phospholipase D (PLD) and increased localization of PLD1 to ATG16L1-positive membranes. We propose that HS1BP3 regulates autophagy by modulating the PA content of the ATG16L1-positive autophagosome precursor membranes through PLD1 activity and localization. Our findings provide key insights into how autophagosome formation is regulated by a novel negative-feedback mechanism on membrane lipids.

• Lystad, Alf Håkon & Simonsen, Anne (2016). Phosphoinositide-binding proteins in autophagy. FEBS Letters. ISSN 0014-5793. s. 2454–2468. doi: 10.1002/1873-3468.12286. Fulltekst i vitenarkiv
• Dragich, Joanna M; Kuwajima, Takaaki; Hirose-Ikeda, Megumi; Yoon, Michael S; Eenjes, Evelien & Bosco, Joan R [Vis alle 18 forfattere av denne artikkelen] (2016). Autophagy linked FYVE (Alfy/WDFY3) is required for establishing neuronal connectivity in the mammalian brain. eLIFE. 5(September). doi: 10.7554/eLife.14810. Fulltekst i vitenarkiv
• Lystad, Alf Håkon & Simonsen, Anne (2015). Assays to monitor aggrephagy. Methods. ISSN 1046-2023. 75, s. 112–119. doi: 10.1016/j.ymeth.2014.12.019. Fulltekst i vitenarkiv
• Lystad, Alf Håkon; Ichimura, Yoshinobu; Takagi, K; Yang, Yinjie; Pankiv, Serhiy & Kanegae, Yumi [Vis alle 12 forfattere av denne artikkelen] (2014). Structural determinants in GABARAP required for the selective binding and recruitment of ALFY to LC3B-positive structures. EMBO Reports. ISSN 1469-221X. 15(5), s. 557–565. doi: 10.1002/embr.201338003. Fulltekst i vitenarkiv
• Isakson, Pauline; Lystad, Alf Håkon; Breen, Kamilla; Koster, Gerbrand; Stenmark, Harald Alfred & Simonsen, Anne (2013). TRAF6 mediates ubiquitination of KIF23/MKLP1 and is required for midbody ring degradation by selective autophagy. Autophagy. ISSN 1554-8627. 9(12), s. 1955–1964. doi: 10.4161/auto.26085. Fulltekst i vitenarkiv

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• Lystad, Alf Håkon; Sporstol, Marita; Foroughi, Masoud; Roos, Norbert; Berg, Trond & Eskild, Winnie (2009). Regulation of VEGF expression by vitamin D i hepatic stellate cells - possible attenuation by the nuclear receptor coregulator NCY-G1. Fulltekst i vitenarkiv
• Lystad, Alf Håkon; Sporstol, Marita; Foroughi, Masoud; Roos, Norbert; Berg, Trond & Eskild, Winnie (2009). Regulation of VEGF expression by vitamin D in hepatic stellate cells - possible attenuation by the nuclear receptor coregulator NCU-G1. Fulltekst i vitenarkiv

Se alle arbeider i NVA