bims-tofagi Biomed News
on Mitophagy
Issue of 2024–11–10
two papers selected by
Michele Frison, University of Cambridge and Aitor Martínez Zarate, Euskal Herriko Unibertsitatea
  1. USP14 inhibition enhances Parkin-independent mitophagy in iNeurons.
  2. Analysis of quality control pathways for the translocase of the outer mitochondrial membrane.
  1. Pharmacol Res. 2024 Oct 30. pii: S1043-6618(24)00429-8. [Epub ahead of print] 107484
    USP14 inhibition enhances Parkin-independent mitophagy in iNeurons.
    Bernardo Greta, A Prado Miguel, Dashtmian Anna Roshani, Mariavittoria Favaro, Sofia Mauri, Alice Borsetto, Elena Marchesan, Joao A Paulo, Steve P Gygi, Daniel J Finley, Elena Ziviani.
      Loss of proteostasis is well documented during physiological aging and depends on the progressive decline in the activity of two major degradative mechanisms: the ubiquitin-proteasome system (UPS) and the autophagy-lysosomal pathway. This decline in proteostasis is exacerbated in age-associated neurodegenerative diseases, such as Parkinson's Disease (PD). In PD, patients develop an accumulation of aggregated proteins and dysfunctional mitochondria, which leads to ROS production, neuroinflammation and neurodegeneration. We recently reported that inhibition of the deubiquitinating enzyme USP14, which is known to enhance both the UPS and autophagy, increases lifespan and rescues the pathological phenotype of two Drosophila models of PD. Studies on the effects of USP14 inhibition in mammalian neurons have not yet been conducted. To close this gap, we exploited iNeurons differentiated from human embryonic stem cells (hESCs), and investigated the effect of inhibiting USP14 in these cultured neurons. Quantitative global proteomics analysis performed following genetic ablation or pharmacological inhibition of USP14 demonstrated that USP14 loss of function specifically promotes mitochondrial autophagy in iNeurons. Biochemical and imaging data also showed that USP14 inhibition enhances mitophagy. The mitophagic effect of USP14 inhibition proved to be PINK1/Parkin- independent, instead relying on expression of the mitochondrial E3 Ubiquitin Ligase MITOL/MARCH5. Notably, USP14 inhibition normalized the mitochondrial defects of Parkin KO human neurons.
    Keywords:  Autophagy; MARCH5/MITOL; Mitophagy; PINK1; Parkin; UPS; USP14
    DOI:  https://doi.org/10.1016/j.phrs.2024.107484
  2. Methods Enzymol. 2024 ;pii: S0076-6879(24)00395-1. [Epub ahead of print]707 565-584
    Analysis of quality control pathways for the translocase of the outer mitochondrial membrane.
    Lara Calvo Santos, Fabian den Brave.
      The functionality of mitochondria depends on the import of proteins synthesized on cytosolic ribosomes. Impaired import into mitochondria results in mitochondrial dysfunction and proteotoxic accumulation of precursor proteins in the cytosol. All proteins sorted to inner mitochondrial compartments are imported via the translocase of the outer membrane (TOM) complex. Premature protein folding, a reduction of the mitochondrial membrane potential or defects in translocases can result in precursor arrest during translocation, thereby clogging the TOM channel and blocking protein import. In recent years, different pathways have been identified, which employ the cytosolic ubiquitin-proteasome system in the extraction and turnover of precursor proteins from the TOM complex. Central events in this process are the modification of arrested precursor proteins with ubiquitin, their extraction by AAA-ATPases and subsequent degradation by the 26 S proteasome. Analysis of these processes is largely facilitated by the expression of model proteins that function as efficient "cloggers" of the import machinery. Here we describe the use of such clogger proteins and how their handling by the protein quality control machinery can be monitored. We provide protocols to study the extent of clogging, the ubiquitin-modification of arrested precursor proteins and their turnover by the 26 S proteasome.
    Keywords:  Mitochondria; Proteasome; Protein import; Protein quality control; Ubiquitin
    DOI:  https://doi.org/10.1016/bs.mie.2024.07.050
This page is being maintained by Thomas Krichel. It was last updated on 2024‒12‒07 at 23:58.