PubMed · 3334480
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
T Hase, H Matsubara. 1987. [Mitochondrial proteins].. https://pubmed.ncbi.nlm.nih.gov/3334480/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
The capsaicin receptor, TRPV1, mediates the detection of noxious chemical and thermal stimuli by nociceptors, primary sensory neurons of the pain pathway. Overactivation of TRPV1 leads to cellular damage or death through calcium entry and excitotoxicity. We have exploited this phenomenon to conduct a systematic analysis of excitotoxicity through a genome-wide CRISPRi screen, thereby revealing a comprehensive network of regulatory pathways. We show that decreased expression of mitochondrial electron transport chain (ETC) components protects against capsaicin-induced toxicity and other challenges by mitigating both calcium imbalance and the generation of mitochondrial reactive oxygen species via distinct pathways. Moreover, we confirm the regulatory roles of the ETC in sensory neurons through gain-of-function and loss-of-function experiments. Interestingly, TRPV1+ sensory neurons maintain lower expression of ETC components and can better tolerate excitotoxicity and oxidative stress compared with other sensory neuron subtypes, implicating ETC tuning as an intrinsic cellular strategy that protects nociceptors against excitotoxicity.
Yeast lacking copper-zinc superoxide dismutase (CuZnSOD), manganese superoxide dismutase (SOD), catalase T, or metallothionein were studied using long-term stationary phase (10-45 days) as a simple model system to study the roles of antioxidant enzymes in aging. In well aerated cultures, the lack of either SOD resulted in dramatic loss of viability over the first few weeks of culture, with the CuZnSOD mutant showing the more severe defect. The double SOD mutant died within a few days. The severity reversed in low aeration; the CuZnSOD mutant remained viable longer than the manganese SOD mutant. To test whether reactive oxygen species generated during respiration play an important role in the observed cellular death, growth in nonfermentable carbon sources was measured. All strains grew under low aeration, indicating respiratory competence. High aeration caused much reduced growth in single SOD mutants, and the double mutant failed to grow. However, removal of respiration via another mutation dramatically increased short term survival and reversed the known air-dependent methionine and lysine auxotrophies. Our results suggest strongly that mitochondrial respiration is a major source of reactive oxygen species in vivo, as has been shown in vitro, and that these species are produced even under low aeration.
The catalytic subunit of a membrane-bound pyrophosphatase was purified by electroendosmotic preparative electrophoresis from etiolated pea stem mitochondria. The enzyme was identified as a single peak relatively pure, because only a very limited number of polypeptides were detectable by SDS/PAGE of the active fractions. The pyrophosphatase was associated to a band with a molecular mass of 35 kDa, showing a specific activity of 0.7 mumol Pi . mg-1 protein . min-1 (37 degrees C, pH 8.0) and an apparent Km value of 200 microM. The hydrolytic activity required Mg2+, was inhibited by imidodiphosphate (HNO6P2Na4), Ca2+, F- and was stimulated by phospholipids. Cardiolipin, phophatidylcholine and phosphatidylethanolamine had the maximal activating effect. The isolated protein is very similar to the catalytic subunit of pyrophosphatases isolated from rat liver (beta-subunit) and Saccharomyces cerevisiae mitochondria.