Transient mitochondrial permeability transition mediates excitotoxicity in glutamate-sensitive NSC34 D motor neuron-like cells

Abstract

Excitotoxicity plays a critical role in neurodegenerative disease. Cytosolic calcium overload and mitochondrial dysfunction are among the major mediators of high level glutamate-induced neuron death. Here, we show that the transient opening of mitochondrial permeability transition pore (tMPT) bridges cytosolic calcium signaling and mitochondrial dysfunction and mediates glutamate-induced neuron death. Incubation of the differentiated motor neuron-like NSC34D cells with glutamate (1 mM) acutely induces cytosolic calcium transient (30% increase). Glutamate also stimulates tMPT opening, as reflected by a 2-fold increase in the frequency of superoxide flash, a bursting superoxide production event in individual mitochondria coupled to tMPT opening. The glutamate-induced tMPT opening is attenuated by suppressing cytosolic calcium influx and abolished by inhibiting mitochondrial calcium uniporter (MCU) with Ru360 (100 µM) or MCU shRNA. Further, increased cytosolic calcium is sufficient to induce tMPT in a mitochondrial calcium dependent manner. Finally, chronic glutamate incubation (24 hr) persistently elevates the probability of tMPT opening, promotes oxidative stress and induces neuron death. Attenuating tMPT activity or inhibiting MCU protects NSC34D cells from glutamate-induced cell death. These results indicate that high level glutamate-induced neuron toxicity is mediated by tMPT, which connects increased cytosolic calcium signal to mitochondrial dysfunction.

Mitochondrial flash as a novel biomarker of mitochondrial respiration in the heart

“…Therefore, simultaneous or parallel monitoring of other key parameters, including OCR, membrane potential, ATP, pH, and ROS, may be needed to provide a comprehensive picture of mitochondrial respiration status under certain conditions. Although this study focuses on the flash-respiration coupling under physiological condition, the same mechanism may apply to pathological conditions, such as heart failure, ischemia reperfusion, neurotoxicity, and muscle disorders (22,34,45,51,53). We speculate that the establishment of flash-respiration coupling will stimulate its application in diseases and, together with other indicators, advance our understanding of the role of mitochondria in human disease.…”

Mitochondrial flashes: From indicator characterization to in vivo imaging

“…Enzymatically isolated adult rat ventricular myocytes in primary culture were infected with adenovirus carrying the mt-cpYFP coding sequence at a multiplicity of infection of 100 and cultured for 2 to 3 days following previously reported methods [39]. Similar infection conditions were used when expressing mt-cpYFP in other cell types [27]. …”

“…A number of reports have used mt-cpYFP and other ROS indicators to confirm the existence of transient mitochondrial flash-like events. Collectively, these studies suggest that mitochondrial flashes have important physiological and pathophysiological significances, since flash frequency is closely associated with muscle contraction [16, 17, 21], muscle development [22], cell differentiation [23], neuron development and degeneration [24–27], aging [15], and wound healing [28]. Therefore, real-time monitoring of mitochondrial flashes in living cells, organs and animals provides a unique means for studying the role of integrated mitochondrial functions in health and disease, and represent a significant advance in mitochondrial biomedicine.…”

Cardio-protective effects of cyclosporine in doxorubicin induced cardiotoxicity and assessment of Interleukin-17 as biomarker of cardiac injury an animal model study

“…Cyclophillin-D is an input element of mitochondrial permeability transition pore (MPTP), in cardiotoxicity and cardiac ischemic-reperfusion damage there was an induction of MPTP [21], thus, cyclosporine diminishes the myocardial infarction size in mice but not in mice lacking cyclophillin-D [22].…”