bims-mikwok 2022-08-21 papers

Issue of 2022–08–21
five papers selected by
Avinash N. Mukkala, University of Toronto

Biochem Biophys Res Commun. 2022 Aug 05. pii: S0006-291X(22)01109-3. [Epub ahead of print]625 167-173

PINK1-dependent and Parkin-independent mitophagy is involved in reprogramming of glycometabolism in pancreatic cancer cells.

Natsumi Miyazaki, Reika Shiratori, Taichi Oshima, Zhiheng Zhang, Robert Valencia, Joshua Kranrod, Liye Fang, John M Seubert, Kousei Ito, Shigeki Aoki.

Cancer cells rely on glycolysis to generate ATP for survival. However, inhibiting glycolysis is insufficient for the eradication of cancer cells because glycolysis-suppressed cells undergo metabolic reprogramming toward mitochondrial oxidative phosphorylation. We previously described that upon glycolytic suppression in pancreatic cancer cells, intracellular glycometabolism is shifted toward mitochondrial oxidative phosphorylation in an autophagy-dependent manner for cellular survival. Here, we hypothesized that mitophagy, which selectively degrades mitochondria via autophagy, is involved in mitochondrial activation under metabolic reprogramming. We revealed that glycolytic suppression notably increased mitochondrial membrane potential and mitophagy in a pancreatic cancer cell model (PANC-1). PTEN-induced kinase 1 (PINK1), a ubiquitin kinase that regulates mitophagy in healthy cells, regulated mitochondrial activation through mitophagy by glycolytic suppression. However, Parkin, a ubiquitin ligase regulated by PINK1 in healthy cells to induce mitophagy, was not involved in the PINK1-dependent mitophagy of the cancer glycometabolism. These results imply that cancer cells and healthy cells have different regulatory pieces of machinery for mitophagy, and inhibition of cancer-specific mechanisms may be a potential strategy for cancer therapy targeting metabolic reprogramming.

Keywords: Glycometabolism; Mitophagy; PINK1; Pancreatic cancer; Parkin

DOI: https://doi.org/10.1016/j.bbrc.2022.08.004

Cell Rep. 2022 Aug 16. pii: S2211-1247(22)01015-4. [Epub ahead of print]40(7): 111198

Mitochondrial hyperfusion via metabolic sensing of regulatory amino acids.

Mahmud O Abdullah, Run X Zeng, Chelsea L Margerum, David Papadopoli, Cian Monnin, Kaylee B Punter, Charles Chu, Mohammad Al-Rofaidi, Naser F Al-Tannak, Domenica Berardi, Zahra Rattray, Nicholas J W Rattray, Sheela A Abraham, Eeva-Liisa Eskelinen, David G Watson, Daina Avizonis, Ivan Topisirovic, Edmond Y W Chan.

The relationship between nutrient starvation and mitochondrial dynamics is poorly understood. We find that cells facing amino acid starvation display clear mitochondrial fusion as a means to evade mitophagy. Surprisingly, further supplementation of glutamine (Q), leucine (L), and arginine (R) did not reverse, but produced stronger mitochondrial hyperfusion. Interestingly, the hyperfusion response to Q + L + R was dependent upon mitochondrial fusion proteins Mfn1 and Opa1 but was independent of MTORC1. Metabolite profiling indicates that Q + L + R addback replenishes amino acid and nucleotide pools. Inhibition of fumarate hydratase, glutaminolysis, or inosine monophosphate dehydrogenase all block Q + L + R-dependent mitochondrial hyperfusion, which suggests critical roles for the tricarboxylic acid (TCA) cycle and purine biosynthesis in this response. Metabolic tracer analyses further support the idea that supplemented Q promotes purine biosynthesis by serving as a donor of amine groups. We thus describe a metabolic mechanism for direct sensing of cellular amino acids to control mitochondrial fusion and cell fate.

Keywords: CP: Cell biology; CP: Metabolism; Drp1; Mfn1; Mfn2; Opa1; amino acid sensing; arginine; dynamics; fusion; glutamine; hyperfusion; leucine; mitochondria; stable isotope tracer

DOI: https://doi.org/10.1016/j.celrep.2022.111198

Sci Adv. 2022 Aug 19. 8(33): eabp9245

High-efficiency quantitative control of mitochondrial transfer based on droplet microfluidics and its application on muscle regeneration.

Jiayu Sun, Hiu Tung Jessica Lo, Lei Fan, Tsz Lam Yiu, Adnan Shakoor, Gang Li, Wayne Y W Lee, Dong Sun.

Mitochondrial transfer is a spontaneous process to restore damaged cells in various pathological conditions. The transfer of mitochondria to cell therapy products before their administration can enhance therapeutic outcomes. However, the low efficiency of previously reported methods limits their clinical application. Here, we developed a droplet microfluidics-based mitochondrial transfer technique that can achieve high-efficiency and high-throughput quantitative mitochondrial transfer to single cells. Because mitochondria are essential for muscles, myoblast cells and a muscle injury model were used as a proof-of-concept model to evaluate the proposed technique. In vitro and in vivo experiments demonstrated that C2C12 cells with 31 transferred mitochondria had significant improvements in cellular functions compared to those with 0, 8, and 14 transferred mitochondria and also had better therapeutic effects on muscle regeneration. The proposed technique can considerably promote the clinical application of mitochondrial transfer, with optimized cell function improvements, for the cell therapy of mitochondria-related diseases.

DOI: https://doi.org/10.1126/sciadv.abp9245

J Hepatol. 2022 Aug 16. pii: S0168-8278(22)02993-2. [Epub ahead of print]

Hepatectomy-induced apoptotic extracellular vesicles stimulate neutrophils to secrete regenerative growth factors.

BACKGROUND AND AIMS: Surgical resection of the cancerous tissue represents one of the few curative treatment options for neoplastic liver disease. Such partial hepatectomy (PHx) induces hepatocyte hyperplasia to restore liver function. PHx is associated with bacterial translocation, leading to an immediate immune response involving neutrophils and macrophages, which are indispensable for the priming phase of liver regeneration. Additionally, PHx induces longer-lasting intrahepatic apoptosis. Here, we investigated the effect of apoptotic extracellular vesicles (aEVs) on neutrophil function and their role in this later phase of liver regeneration.
METHODS: A total of 124 patients undergoing PHx were included in this study. Blood levels of the apoptosis marker caspase-cleaved cytokeratin-18 (M30) and circulating aEVs were analyzed pre-operatively and on the first and fifth post-operative days. Additionally, the in vitro effects of aEVs on the neutrophil secretome, phenotype and functions were investigated.
RESULTS: Circulating aEVs increased at the first postoperative day. This was associated with higher concentrations of M30, which was only observed in patients with complete liver recovery. Efferocytosis of aEVs by neutrophils induced an activated phenotype (CD11bhighCD16highCD66bhighCD62Llow), however, classical inflammatory responses such as NETosis, respiratory burst, degranulation, or secretion of pro-inflammatory cytokines could not be observed. Instead, efferocytosing neutrophils released various growth factors including fibroblast growth factor-2 and hepatocyte growth factor (HGF). Accordingly, we observed an increase of HGF+ neutrophils after PHx and a correlation of plasma HGF with M30 levels.
CONCLUSIONS: These data suggest that the clearance of PHx-induced aEVs leads to a population of non-inflammatory, but regenerative neutrophils, which may support human liver regeneration.
LAY SUMMARY: In this study, we could show that partial hepatectomy induces apoptosis in the residual liver tissue. This results in the release of apoptotic vesicles into the blood flow, where they are cleared by circulating neutrophils, which respond by secreting hepatocyte growth factors and thus might support liver regeneration.

Keywords: Apoptosis; Extracellular Vesicles; Hepatectomy; Liver Regeneration; Neutrophils

DOI: https://doi.org/10.1016/j.jhep.2022.07.027

Shock. 2022 Jul 01. 58(1): 38-44

TRAUMA-DERIVED EXTRACELLULAR VESICLES ARE SUFFICIENT TO INDUCE ENDOTHELIAL DYSFUNCTION AND COAGULOPATHY.

Ahmad Zeineddin, Feng Wu, Jing-Fei Dong, Huang Huang, Lin Zou, Wei Chao, Brooke Dorman, Rosemary A Kozar.

ABSTRACTINTRODUCTION: Although a number of studies have demonstrated increased release of extracellular vesicles (EVs) and changes in their origin differentials after trauma, the biologic significance of EVs is not well understood. We hypothesized that EVs released after trauma/hemorrhagic shock (HS) contribute to endotheliopathy and coagulopathy. To test this hypothesis, adoptive transfer experiments were performed to determine whether EVs derived from severely injured patients in shock were sufficient to induce endothelial dysfunction and coagulopathy. Methods: Total EVs were enriched from plasma of severely injured trauma/HS patients or minimally injured patients by ultracentrifugation and characterized for size and numbers. Under isoflurane anesthesia, noninjured naive C57BL/6J mice were administered EVs at varying concentrations and compared with mice receiving equal volume vehicle (phosphate-buffered saline (PBS)) or to mice receiving EVs from minimally injured patients. Thirty minutes after injection, mice were sacrificed, and blood was collected for thrombin generation (thrombin-antithrombin, thrombin-antithrombin complex [TAT] assay) and syndecan-1 by enzyme-linked immunoabsorbent assay (ELISA). Lungs were harvested for examination of histopathologic injury and costained with von Willebrand factor and fibrin to identify intravascular coagulation. Bronchial alveolar lavage fluid was aspirated from lungs for protein measurement as an indicator of the endothelial permeability. Data are presented as mean ± SD, P < 0.05 was considered significant, and t test was used. Results: An initial proof-of-concept experiment was performed in naive mice receiving EVs purified from severely injured trauma/HS patients (Injury Severity Score [ISS], 34 ± 7) at different concentrations (5 × 106 to 3.1 × 109/100 μL/mouse) and compared with PBS (control) mice. Neither TAT nor syndecan-1 levels were significantly different between groups at 30 minutes after EV infusion. However, lung vascular permeability and histopathologic injury were significantly higher in the EV group, and lung tissues demonstrated intravascular fibrin deposition. Based on these data, EVs from severely injured trauma/HS patients (ISS, 32 ± 6) or EVs from minimally injured patients (ISS, 8 ± 3) were administered to naive mice at higher concentrations (1 × 109 to 1 × 1010 EV/100 μL/mouse). Compared with mice receiving EVs from minimally injured patients, plasma TAT and syndecan-1 levels were significantly higher in the trauma/HS EV group. Similarly, bronchial alveolar lavage protein and lung histopathologic injury were higher in the trauma/HS EV group, and lung tissues demonstrated enhanced intravascular fibrin deposition. Conclusion: These data demonstrate that trauma/HS results in the systemic release of EVs, which are capable of inducing endotheliopathy as demonstrated by elevated syndecan-1 and increased permeability and coagulopathy as demonstrated by increased TAT and intravascular fibrin deposition. Targeting trauma-induced EVs may represent a novel therapeutic strategy.

DOI: https://doi.org/10.1097/SHK.0000000000001950