bims-mitpro 2024-06-23 papers

bims-mitpro

Biomed News

on Mitochondrial proteostasis

Issue of 2024–06–23
six papers selected by
Andreas Kohler, Umeå University

Mitochondrial unfolded protein response (UPRmt): what we know thus far.
DYRK1A signalling synchronizes the mitochondrial import pathways for metabolic rewiring.
Tissue-specific roles of mitochondrial unfolded protein response during obesity.
Olfaction regulates peripheral mitophagy and mitochondrial function.
Suppressed basal mitophagy drives cellular aging phenotypes that can be reversed by a p62-targeting small molecule.
Mitochondrial proteases modulate mitochondrial stress signalling and cellular homeostasis in health and disease.

Front Cell Dev Biol. 2024 ;12 1405393

Mitochondrial unfolded protein response (UPRmt): what we know thus far.

Angie K Torres, Veronika Fleischhart, Nibaldo C Inestrosa.

  Mitochondria are key organelles for the optimal function of the cell. Among their many functions, they maintain protein homeostasis through their own proteostatic machinery, which involves proteases and chaperones that regulate protein import and folding inside mitochondria. In the early 2000s, the mitochondrial unfolded protein response (UPRmt) was first described in mammalian cells. This stress response is activated by the accumulation of unfolded/misfolded proteins within the mitochondrial matrix, which results in the transmission of a signal to the nucleus to increase the expression of proteases and chaperones to address the abnormal mitochondrial protein load. After its discovery, this retrograde signaling pathway has also been described in other organisms of different complexities, suggesting that it is a conserved stress response. Although there are some specific differences among organisms, the mechanism of this stress response is mostly similar and involves the transmission of a signal from mitochondria to the nucleus that induces chromatin remodeling to allow the binding of specific transcription factors to the promoters of chaperones and proteases. In the last decade, proteins and signaling pathways that could be involved in the regulation of the UPRmt, including the Wnt signaling pathway, have been described. This minireview aims to summarize what is known about the mechanism of the UPRmt and its regulation, specifically in mammals and C. elegans.

Keywords:  Caenorhabditis elegans; UPRmt; misfolded protein; mitochondria; stress; wnt signaling

DOI:  https://doi.org/10.3389/fcell.2024.1405393
Nat Commun. 2024 Jun 20. 15(1): 5265

DYRK1A signalling synchronizes the mitochondrial import pathways for metabolic rewiring.

Adinarayana Marada, Corvin Walter, Tamara Suhm, Sahana Shankar, Arpita Nandy, Tilman Brummer, Ines Dhaouadi, F-Nora Vögtle, Chris Meisinger.

Mitochondria require an extensive proteome to maintain a variety of metabolic reactions, and changes in cellular demand depend on rapid adaptation of the mitochondrial protein composition. The TOM complex, the organellar entry gate for mitochondrial precursors in the outer membrane, is a target for cytosolic kinases to modulate protein influx. DYRK1A phosphorylation of the carrier import receptor TOM70 at Ser91 enables its efficient docking and thus transfer of precursor proteins to the TOM complex. Here, we probe TOM70 phosphorylation in molecular detail and find that TOM70 is not a CK2 target nor import receptor for MIC19 as previously suggested. Instead, we identify TOM20 as a MIC19 import receptor and show off-target inhibition of the DYRK1A-TOM70 axis with the clinically used CK2 inhibitor CX4945 which activates TOM20-dependent import pathways. Taken together, modulation of DYRK1A signalling adapts the central mitochondrial protein entry gate via synchronization of TOM70- and TOM20-dependent import pathways for metabolic rewiring. Thus, DYRK1A emerges as a cytosolic surveillance kinase to regulate and fine-tune mitochondrial protein biogenesis.

DOI: https://doi.org/10.1038/s41467-024-49611-4
Obes Rev. 2024 Jun 16. e13791

Tissue-specific roles of mitochondrial unfolded protein response during obesity.

Fernanda S Carneiro, Carlos K Katashima, Joshua D Dodge, Dennys E Cintra, José Rodrigo Pauli, Adelino S R Da Silva, Eduardo R Ropelle.

  Obesity is a worldwide multifactorial disease caused by an imbalance in energy metabolism, increasing adiposity, weight gain, and promoting related diseases such as diabetes, cardiovascular diseases, neurodegeneration, and cancer. Recent findings have reported that metabolic stress related to obesity induces a mitochondrial stress response called mitochondrial unfolded protein response (UPRmt), a quality control pathway that occurs in a nuclear DNA-mitochondria crosstalk, causing transduction of chaperones and proteases under stress conditions. The duality of UPRmt signaling, with both beneficial and detrimental effects, acts in different contexts depending on the tissue, cell type, and physiological states, affecting the mitochondrial function and efficiency and the metabolism homeostasis during obesity, which remains not fully clarified. Therefore, this review discusses the most recent findings regarding UPRmt signaling during obesity, bringing an overview of UPRmt across different metabolic tissues.

Keywords:  metabolism; mitochondria; mitochondrial unfolded protein response; obesity

DOI:  https://doi.org/10.1111/obr.13791
Sci Adv. 2024 Jun 21. 10(25): eadn0014

Olfaction regulates peripheral mitophagy and mitochondrial function.

Julian G Dishart, Corinne L Pender, Koning Shen, Hanlin Zhang, Megan Ly, Madison B Webb, Andrew Dillin.

The central nervous system coordinates peripheral cellular stress responses, including the unfolded protein response of the mitochondria (UPRMT); however, the contexts for which this regulatory capability evolved are unknown. UPRMT is up-regulated upon pathogenic infection and in metabolic flux, and the olfactory nervous system has been shown to regulate pathogen resistance and peripheral metabolic activity. Therefore, we asked whether the olfactory nervous system in Caenorhabditis elegans controls the UPRMT cell nonautonomously. We found that silencing a single inhibitory olfactory neuron pair, AWC, led to robust induction of UPRMT and reduction of oxidative phosphorylation dependent on serotonin signaling and parkin-mediated mitophagy. Further, AWC ablation confers resistance to the pathogenic bacteria Pseudomonas aeruginosa partially dependent on the UPRMT transcription factor atfs-1 and fully dependent on mitophagy machinery. These data illustrate a role for the olfactory nervous system in regulating whole-organism mitochondrial dynamics, perhaps in preparation for postprandial metabolic stress or pathogenic infection.

DOI: https://doi.org/10.1126/sciadv.adn0014
Dev Cell. 2024 May 20. pii: S1534-5807(24)00295-8. [Epub ahead of print]

Suppressed basal mitophagy drives cellular aging phenotypes that can be reversed by a p62-targeting small molecule.

George Kelly, Tetsushi Kataura, Johan Panek, Gailing Ma, Hanna Salmonowicz, Ashley Davis, Hannah Kendall, Charlotte Brookes, Daniel Moscoh Ayine-Tora, Peter Banks, Glyn Nelson, Laura Dobby, Patricia R Pitrez, Laura Booth, Lydia Costello, Gavin D Richardson, Penny Lovat, Stefan Przyborski, Lino Ferreira, Laura Greaves, Karolina Szczepanowska, Thomas von Zglinicki, Satomi Miwa, Max Brown, Michael Flagler, John E Oblong, Charles C Bascom, Bernadette Carroll, Jóhannes Reynisson, Viktor I Korolchuk.

  Selective degradation of damaged mitochondria by autophagy (mitophagy) is proposed to play an important role in cellular homeostasis. However, the molecular mechanisms and the requirement of mitochondrial quality control by mitophagy for cellular physiology are poorly understood. Here, we demonstrated that primary human cells maintain highly active basal mitophagy initiated by mitochondrial superoxide signaling. Mitophagy was found to be mediated by PINK1/Parkin-dependent pathway involving p62 as a selective autophagy receptor (SAR). Importantly, this pathway was suppressed upon the induction of cellular senescence and in naturally aged cells, leading to a robust shutdown of mitophagy. Inhibition of mitophagy in proliferating cells was sufficient to trigger the senescence program, while reactivation of mitophagy was necessary for the anti-senescence effects of NAD precursors or rapamycin. Furthermore, reactivation of mitophagy by a p62-targeting small molecule rescued markers of cellular aging, which establishes mitochondrial quality control as a promising target for anti-aging interventions.

Keywords:  PINK1; Parkin; aging; autophagy; mitophagy; nicotinamide; nicotinamide riboside; p62; rapamycin; redox; senescence

DOI:  https://doi.org/10.1016/j.devcel.2024.04.020
Biochimie. 2024 Jun 19. pii: S0300-9084(24)00141-X. [Epub ahead of print]

Mitochondrial proteases modulate mitochondrial stress signalling and cellular homeostasis in health and disease.

Nicoleta Moisoi.

Maintenance of mitochondrial homeostasis requires a plethora of coordinated quality control and adaptations' mechanisms in which mitochondrial proteases play a key role. Their activation or loss of function reverberate beyond local mitochondrial biochemical and metabolic remodelling into coordinated cellular pathways and stress responses that feedback onto the mitochondrial functionality and adaptability. Mitochondrial proteolysis modulates molecular and organellar quality control, metabolic adaptations, lipid homeostasis and regulates transcriptional stress responses. Defective mitochondrial proteolysis results in disease conditions most notably, mitochondrial diseases, neurodegeneration and cancer. Here, it will be discussed how mitochondrial proteases and mitochondria stress signalling impact cellular homeostasis and determine the cellular decision to survive or die, how these processes may impact disease etiopathology, and how modulation of proteolysis may offer novel therapeutic strategies.

DOI: https://doi.org/10.1016/j.biochi.2024.06.005