A new target for an old DUB: UCH-L1 regulates mitofusin-2 levels, altering mitochondrial morphology, function and calcium uptake
Fernanda M. Cerqueira,
Sophia von Stockum,
Marta Giacomello,
Inna Goliand,
Pamela Kakimoto,
Elena Marchesan,
Diego De Stefani,
Alicia J. Kowaltowski,
Elena Ziviani,
Orian S. Shirihai
Affiliations
Fernanda M. Cerqueira
Obesity Research Center, Molecular Medicine, Boston University School of Medicine, Boston, MA, 02111, USA; National Institute for Biotechnology in the Negev, Ben Gurion University, Beer-Sheva, 8410501, Israel; Department of Biology, University of Padua, Padua, 35121, Italy
Sophia von Stockum
Department of Biology, University of Padua, Padua, 35121, Italy
Marta Giacomello
Department of Biology, University of Padua, Padua, 35121, Italy; Department of Biomedical Sciences, University of Padua, 35121, Italy
Inna Goliand
National Institute for Biotechnology in the Negev, Ben Gurion University, Beer-Sheva, 8410501, Israel
Pamela Kakimoto
Departmento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, 05508-900, Brazil
Elena Marchesan
Department of Biology, University of Padua, Padua, 35121, Italy
Diego De Stefani
Department of Biomedical Sciences, University of Padua, 35121, Italy
Alicia J. Kowaltowski
Departmento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, 05508-900, Brazil
Elena Ziviani
Department of Biology, University of Padua, Padua, 35121, Italy
Orian S. Shirihai
Obesity Research Center, Molecular Medicine, Boston University School of Medicine, Boston, MA, 02111, USA; UCLA Section of Endocrinology, Department of Medicine, David Geffen School of Medicine, UCLA, CA, 9095-7073, USA; Corresponding author. UCLA Section of Endocrinology, Department of Medicine, David Geffen School of Medicine, UCLA, CA, 9095-7073, USA.
UCH-L1 is a deubiquitinating enzyme (DUB), highly abundant in neurons, with a sub-cellular localization dependent on its farnesylation state. Despite UCH-L1′s association with familial Parkinson's Disease (PD), the effects on mitochondrial bioenergetics and quality control remain unexplored. Here we investigated the role of UCHL-1 in mitochondrial dynamics and bioenergetics. We demonstrate that knock-down (KD) of UCH-L1 in different cell lines reduces the levels of the mitochondrial fusion protein Mitofusin-2, but not Mitofusin-1, resulting in mitochondrial enlargement and disruption of the tubular network. This was associated with lower tethering between mitochondria and the endoplasmic reticulum, consequently altering mitochondrial calcium uptake. Respiratory function was also altered, as UCH-L1 KD cells displayed higher proton leak and maximum respiratory capacity. Conversely, overexpression of UCH-L1 increased Mfn2 levels, an effect dramatically enhanced by the mutation of the farnesylation site (C220S), which drives UCH-L1 binding to membranes. These data indicate that the soluble cytosolic form of UCH-L1 regulates Mitofusin-2 levels and mitochondrial function. These effects are biologically conserved, since knock-down of the corresponding UCH-L1 ortholog in D. melanogaster reduces levels of the mitofusin ortholog Marf and also increases mitochondrial respiratory capacity. We thus show that Mfn-2 levels are directly affected by UCH-L1, demonstrating that the mitochondrial roles of DUBs go beyond controlling mitophagy rates.
