University of Pittsburgh Department of Cell Biology
  • Research

    Mitochondria are endosymbiotic organelles that serve as key hubs for apoptotic regulation, metabolism, and cellular signaling in eukaryotic cells. Over 99% of the ~1500 mitochondrial proteins are encoded in the nuclear genome and depend on specific targeting signals to direct them from the site of synthesis in the cytosol to the appropriate subcompartment. Proper mitochondrial function depends on a process called proteostasis, which ensures that functional proteins are in the right location at the right concentration at the right time. Membrane proteins present unique challenges to the proteostasis network as they must be targeted to the correct membrane and overcome substantial thermodynamic barriers to enter and exit the lipid bilayer, all while avoiding the formation of potentially toxic aggregates in the cytosol. Failures in proteostasis are associated with many neurodegenerative diseases, whereas cancer cells are acutely dependent on robust proteostasis networks to counteract the protein imbalances caused by aneuploidy and dysregulated protein synthesis.  

    Despite the clear physiological importance, our mechanistic understanding of mitochondrial proteostasis is remarkably incomplete. My lab addresses this critical knowledge gap by focusing on three questions: (1) How do quality control factors discriminate between bona fide substrates and functional proteins in a complex cellular environment, including the lipid bilayer; (2) once a substrate is recognized, what are the downstream steps that lead to resolution of proteotoxic stress; and (3) how can we leverage the resulting mechanistic insights to develop therapeutic interventions in cancer and neurodegenerative disease? My lab addresses these important questions using an array of techniques, including: in vitro reconstitution, structural biology, and cell biology.
  • Publications

    1. Fresenius HL, Gaur D, Wohlever ML. The AAA+ protein Msp1 selects substrates by recognizing a hydrophobic mismatch between the substrate transmembrane domain and the lipid bilayer.. bioRxiv. 2023 Jul 11;():. pii: 2023.07.11.548587. doi: 10.1101/2023.07.11.548587. PubMed PMID: 37502992;
    2. Winter JM, Fresenius HL, Cunningham CN, Wei P, Keys HR, Berg J, Bott A, Yadav T, Ryan J, Sirohi D, Tripp SR, Barta P, Agarwal N, Letai A, Sabatini DM, Wohlever ML, Rutter J. Collateral deletion of the mitochondrial AAA+ ATPase ATAD1 sensitizes cancer cells to proteasome dysfunction.. Elife. 2022 Nov 21;11():. doi: 10.7554/eLife.82860. PubMed PMID: 36409067;
    3. Fresenius HL, Wohlever ML. Reconstitution of Msp1 Extraction Activity with Fully Purified Components.. J Vis Exp. 2021 Aug 10;(174):. doi: 10.3791/62928. PubMed PMID: 34459824;
    4. Fresenius HL, Wohlever ML. Sorting out how Msp1 maintains mitochondrial membrane proteostasis.. Mitochondrion. 2019 Nov;49():128-134. doi: 10.1016/j.mito.2019.07.011. PubMed PMID: 31394253;
    5. Wohlever ML, Mateja A, McGilvray PT, Day KJ, Keenan RJ. Msp1 Is a Membrane Protein Dislocase for Tail-Anchored Proteins.. Mol Cell. 2017 Jul 20;67(2):194-202.e6. doi: 10.1016/j.molcel.2017.06.019. PubMed PMID: 28712723;
    6. Itakura E, Zavodszky E, Shao S, Wohlever ML, Keenan RJ, Hegde RS. Ubiquilins Chaperone and Triage Mitochondrial Membrane Proteins for Degradation.. Mol Cell. 2016 Jul 7;63(1):21-33. doi: 10.1016/j.molcel.2016.05.020. PubMed PMID: 27345149;
    7. Wohlever ML, Baker TA, Sauer RT. Roles of the N domain of the AAA+ Lon protease in substrate recognition, allosteric regulation and chaperone activity.. Mol Microbiol. 2014 Jan;91(1):66-78. doi: 10.1111/mmi.12444. PubMed PMID: 24205897;
    8. Wohlever ML, Baker TA, Sauer RT. A mutation in the N domain of Escherichia coli lon stabilizes dodecamers and selectively alters degradation of model substrates.. J Bacteriol. 2013 Dec;195(24):5622-8. doi: 10.1128/JB.00886-13. PubMed PMID: 24123818;
    9. Vieux EF, Wohlever ML, Chen JZ, Sauer RT, Baker TA. Distinct quaternary structures of the AAA+ Lon protease control substrate degradation.. Proc Natl Acad Sci U S A. 2013 May 28;110(22):E2002-8. doi: 10.1073/pnas.1307066110. PubMed PMID: 23674680;
    10. Hesse WR, Steiner M, Wohlever ML, Kamm RD, Hwang W, Lang MJ. Modular aspects of kinesin force generation machinery.. Biophys J. 2013 May 7;104(9):1969-78. doi: 10.1016/j.bpj.2013.03.051. PubMed PMID: 23663840;
    11. Wohlever ML, Nager AR, Baker TA, Sauer RT. Engineering fluorescent protein substrates for the AAA+ Lon protease.. Protein Eng Des Sel. 2013 Apr;26(4):299-305. doi: 10.1093/protein/gzs105. PubMed PMID: 23359718;


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