Evidence for pore opening in mitochondrial membrane during glutamate-induced delayed calcium deregulation in brain neurons

Previously, we have shown that SH-SY5Y cells exposed to high concentrations of methadone died due to a necrotic-like cell death mechanism related to delayed calcium deregulation (DCD). In this study, we show that, in terms of their Ca2+responses to 0.5 mM methadone, SH-SY5Y cells can be pooled into four different groups. In a broad pharmacological survey, the relevance of different Ca2+-related mechanisms on methadone-induced DCD was investigated including extracellular calcium, L-type Ca2+channels,μ-opioid receptor, mitochondrial inner membrane potential, mitochondrial ATP synthesis, mitochondrial Ca2+/2Na+-exchanger, reactive oxygen species, and mitochondrial permeability transition. Only those compounds targeting mitochondria such as oligomycin, FCCP, CGP 37157, and cyclosporine A were able to amend methadone-induced Ca2+dyshomeostasis suggesting that methadone induces DCD by modulating the ability of mitochondria to handle Ca2+. Consistently, mitochondria became dramatically shorter and rounder in the presence of methadone. Furthermore, analysis of oxygen uptake by isolated rat liver mitochondria suggested that methadone affected mitochondrial Ca2+uptake in a respiratory substrate-dependent way. We conclude that methadone causes failure of intracellular Ca2+homeostasis, and this effect is associated with morphological and functional changes of mitochondria. Likely, this mechanism contributes to degenerative side effects associated with methadone treatment.

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MICU1 imparts the mitochondrial uniporter with the ability to discriminate between Ca2+ and Mn2+

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1807811115 ◽

2018 ◽

Vol 115 (34) ◽

pp. E7960-E7969 ◽

Cited By ~ 31

Author(s):

Kimberli J. Kamer ◽

Yasemin Sancak ◽

Yevgenia Fomina ◽

Joshua D. Meisel ◽

Dipayan Chaudhuri ◽

...

Keyword(s):

Metal Toxicity ◽

Mitochondrial Membrane ◽

Genetic Interaction ◽

Wild Type ◽

Chemical Genetic ◽

Auxiliary Subunit ◽

Cellular Metal ◽

Pore Opening ◽

Pass Through ◽

High Conductance

The mitochondrial uniporter is a Ca2+-activated Ca2+ channel complex that displays exceptionally high conductance and selectivity. Here, we report cellular metal toxicity screens highlighting the uniporter’s role in Mn2+ toxicity. Cells lacking the pore-forming uniporter subunit, MCU, are more resistant to Mn2+ toxicity, while cells lacking the Ca2+-sensing inhibitory subunit, MICU1, are more sensitive than the wild type. Consistent with these findings, Caenorhabditis elegans lacking the uniporter’s pore have increased resistance to Mn2+ toxicity. The chemical–genetic interaction between uniporter machinery and Mn2+ toxicity prompted us to hypothesize that Mn2+ can indeed be transported by the uniporter’s pore, but this transport is prevented by MICU1. To this end, we demonstrate that, in the absence of MICU1, both Mn2+ and Ca2+ can pass through the uniporter, as evidenced by mitochondrial Mn2+ uptake assays, mitochondrial membrane potential measurements, and mitoplast electrophysiology. We show that Mn2+ does not elicit the conformational change in MICU1 that is physiologically elicited by Ca2+, preventing Mn2+ from inducing the pore opening. Our work showcases a mechanism by which a channel’s auxiliary subunit can contribute to its apparent selectivity and, furthermore, may have implications for understanding how manganese contributes to neurodegenerative disease.

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Inhibition of glutamate-induced delayed calcium deregulation by 2-APB and La3+ in cultured cortical neurones

Journal of Neurochemistry ◽

10.1111/j.1471-4159.2004.02732.x ◽

2004 ◽

Vol 91 (2) ◽

pp. 471-483 ◽

Cited By ~ 32

Author(s):

Christos Chinopoulos ◽

Akos A. Gerencser ◽

Judit Doczi ◽

Gary Fiskum ◽

Vera Adam-Vizi

Keyword(s):

Calcium Deregulation ◽

Delayed Calcium Deregulation

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