Faculty Opinions recommendation of ATG12 conjugation to ATG3 regulates mitochondrial homeostasis and cell death.

Author(s):  
David C Rubinsztein
2021 ◽  
Vol 5 (8) ◽  
pp. 2087-2100
Author(s):  
Kaitlyn M. Dykstra ◽  
Hannah R. S. Fay ◽  
Ashish C. Massey ◽  
Neng Yang ◽  
Matthew Johnson ◽  
...  

Abstract Leukemia stem cells (LSCs) and therapy-resistant acute myeloid leukemia (AML) blasts contribute to the reinitiation of leukemia after remission, necessitating therapeutic interventions that target these populations. Autophagy is a prosurvival process that allows for cells to adapt to a variety of stressors. Blocking autophagy pharmacologically by using mechanistically distinct inhibitors induced apoptosis and prevented colony formation in primary human AML cells. The most effective inhibitor, bafilomycin A1 (Baf A1), also prevented the in vivo maintenance of AML LSCs in NSG mice. To understand why Baf A1 exerted the most dramatic effects on LSC survival, we evaluated mitochondrial function. Baf A1 reduced mitochondrial respiration and stabilized PTEN-induced kinase-1 (PINK-1), which initiates autophagy of mitochondria (mitophagy). Interestingly, with the autophagy inhibitor chloroquine, levels of enhanced cell death and reduced mitochondrial respiration phenocopied the effects of Baf A1 only when cultured in hypoxic conditions that mimic the marrow microenvironment (1% O2). This indicates that increased efficacy of autophagy inhibitors in inducing AML cell death can be achieved by concurrently inducing mitochondrial damage and mitophagy (pharmacologically or by hypoxic induction) and blocking mitochondrial degradation. In addition, prolonged exposure of AML cells to hypoxia induced autophagic flux and reduced chemosensitivity to cytarabine (Ara-C), which was reversed by autophagy inhibition. The combination of Ara-C with Baf A1 also decreased tumor burden in vivo. These findings demonstrate that autophagy is critical for mitochondrial homeostasis and survival of AML cells in hypoxia and support the development of autophagy inhibitors as novel therapeutic agents for AML.


2019 ◽  
Vol 317 (3) ◽  
pp. C584-C599
Author(s):  
Kurt D. Marshall ◽  
Paula J. Klutho ◽  
Lihui Song ◽  
Maike Krenz ◽  
Christopher P. Baines

Opening of the mitochondrial permeability transition (MPT) pore leads to necrotic cell death. Excluding cyclophilin D (CypD), the makeup of the MPT pore remains conjecture. The purpose of these experiments was to identify novel MPT modulators by analyzing proteins that associate with CypD. We identified Fas-activated serine/threonine phosphoprotein kinase domain-containing protein 1 (FASTKD1) as a novel CypD interactor. Overexpression of FASTKD1 protected mouse embryonic fibroblasts (MEFs) against oxidative stress-induced reactive oxygen species (ROS) production and cell death, whereas depletion of FASTKD1 sensitized them. However, manipulation of FASTKD1 levels had no effect on MPT responsiveness, Ca2+-induced cell death, or antioxidant capacity. Moreover, elevated FASTKD1 levels still protected against oxidative stress in CypD-deficient MEFs. FASTKD1 overexpression decreased Complex-I-dependent respiration and ΔΨm in MEFs, effects that were abrogated in CypD-null cells. Additionally, overexpression of FASTKD1 in MEFs induced mitochondrial fragmentation independent of CypD, activation of Drp1, and inhibition of autophagy/mitophagy, whereas knockdown of FASTKD1 had the opposite effect. Manipulation of FASTKD1 expression also modified oxidative stress-induced caspase-3 cleavage yet did not alter apoptotic death. Finally, the effects of FASTKD1 overexpression on oxidative stress-induced cell death and mitochondrial morphology were recapitulated in cultured cardiac myocytes. Together, these data indicate that FASTKD1 supports mitochondrial homeostasis and plays a critical protective role against oxidant-induced death.


Cell ◽  
2010 ◽  
Vol 142 (4) ◽  
pp. 590-600 ◽  
Author(s):  
Lilliana Radoshevich ◽  
Lyndsay Murrow ◽  
Nan Chen ◽  
Estefania Fernandez ◽  
Srirupa Roy ◽  
...  

2021 ◽  
Author(s):  
Ankita Sarkar ◽  
Malinki Sur ◽  
Puja Dey ◽  
Piyali Mukherjee

The NADase Sarm1 has emerged as an important modulator of programmed axonal degeneration over the past decade but its mode of activation within the cell is not clearly understood. Sarm1 is predominantly expressed in the neurons, kidney and liver but the non-neuronal regulation of Sarm1 remains relatively unexplored. Here we demonstrate that treatment of the human embryonic kidney cell line HEK293 cells with the mitochondrial complex I inhibitor rotenone, induced early loss of NAD+ that preceded induction of Sarm1, a primary mediator of rotenone induced cell death. Interestingly, replenishing NAD+ levels by PARP inhibition, a major NAD+ consumer within the cell, not only restored mitochondrial homeostasis but also prevented subsequent Sarm1 induction by rotenone. These early changes were further marked by a distinct subcellular localization pattern of Sarm1 in the nucleus and the mitochondria that was accompanied by significantly reduced cell death. Taken together, our study provides the first preliminary evidence of temporal regulation of endogenous Sarm1 by fluctuating NAD+ levels induced by rotenone that may act as a biological trigger of Sarm1 activation. This also points towards an important understanding on how PARP inhibitors like PJ34 could be repurposed in the treatment of Sarm1 mediated mitochondrial deficiency disorders.


2021 ◽  
Vol 22 (3) ◽  
pp. 1236
Author(s):  
Kaike Ren ◽  
Lanlan Feng ◽  
Shuangli Sun ◽  
Xiaohong Zhuang

Mitochondrial homeostasis refers to the balance of mitochondrial number and quality in a cell. It is maintained by mitochondrial biogenesis, mitochondrial fusion/fission, and the clearance of unwanted/damaged mitochondria. Mitophagy represents a selective form of autophagy by sequestration of the potentially harmful mitochondrial materials into a double-membrane autophagosome, thus preventing the release of death inducers, which can trigger programmed cell death (PCD). Recent advances have also unveiled a close interconnection between mitophagy and mitochondrial dynamics, as well as PCD in both mammalian and plant cells. In this review, we will summarize and discuss recent findings on the interplay between mitophagy and mitochondrial dynamics, with a focus on the molecular evidence for mitophagy crosstalk with mitochondrial dynamics and PCD.


2021 ◽  
Vol 22 (18) ◽  
pp. 10070
Author(s):  
Elena Paccosi ◽  
Michele Costantino ◽  
Alessio Balzerano ◽  
Silvia Filippi ◽  
Stefano Brancorsini ◽  
...  

Neuroblastoma, the most common extra-cranial solid tumor of early childhood, is one of the major therapeutic challenges in child oncology: it is highly heterogenic at a genetic, biological, and clinical level. The high-risk cases have one of the least favorable outcomes amongst pediatric tumors, and the mortality rate is still high, regardless of the use of intensive multimodality therapies. Here, we observed that neuroblastoma cells display an increased expression of Cockayne Syndrome group B (CSB), a pleiotropic protein involved in multiple functions such as DNA repair, transcription, mitochondrial homeostasis, and cell division, and were recently found to confer cell robustness when they are up-regulated. In this study, we demonstrated that RNAi-mediated suppression of CSB drastically impairs tumorigenicity of neuroblastoma cells by hampering their proliferative, clonogenic, and invasive capabilities. In particular, we observed that CSB ablation induces cytokinesis failure, leading to caspases 9 and 3 activation and, subsequently, to massive apoptotic cell death. Worthy of note, a new frontier in cancer treatment, already proved to be successful, is cytokinesis-failure-induced cell death. In this context, CSB ablation seems to be a new and promising anticancer strategy for neuroblastoma therapy.


2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Sunao Li ◽  
Jiaxin Zhang ◽  
Chao Liu ◽  
Qianliang Wang ◽  
Jun Yan ◽  
...  

Mitochondria are multifaceted organelles that serve to power critical cellular functions, including act as power generators of the cell, buffer cytosolic calcium overload, production of reactive oxygen species, and modulating cell survival. The structure and the cellular location of mitochondria are critical for their function and depend on highly regulated activities such as mitochondrial quality control (MQC) mechanisms. The MQC is regulated by several sets of processes: mitochondrial biogenesis, mitochondrial fusion and fission, mitophagy, and other mitochondrial proteostasis mechanisms such as mitochondrial unfolded protein response (mtUPR) or mitochondrial-derived vesicles (MDVs). These processes are important for the maintenance of mitochondrial homeostasis, and alterations in the mitochondrial function and signaling are known to contribute to the dysregulation of cell death pathways. Recent studies have uncovered regulatory mechanisms that control the activity of the key components for mitophagy. In this review, we discuss how mitophagy is controlled and how mitophagy impinges on health and disease through regulating cell death.


2003 ◽  
Vol 5 (11) ◽  
pp. 761-771 ◽  
Author(s):  
Patrice Petit ◽  
Jacqueline Bréard ◽  
Valérie Montalescot ◽  
Noomen Ben El Hadj ◽  
Thierry Levade ◽  
...  

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