bims-cytox1 2018-06-03 papers

Issue of 2018‒06‒03
four papers selected by
Gavin McStay
New York Institute of Technology

Biosci Biotechnol Biochem. 2018 May 28. 1-7

Suppression of respiratory growth defect of mutant deficient in mitochondrial phospholipase A1 by overexpression of genes involved in coenzyme Q synthesis in Saccharomyces cerevisiae.

Shiho Morisada, Ikuhisa Nishida, Makoto Kawamukai, Hiroyuki Horiuchi, Ryouichi Fukuda.

DDL1 encodes a mitochondrial phospholipase A1 involved in acyl chain remodeling of mitochondrial phospholipids and degradation of cardiolipin in Saccharomyces cerevisiae. The deletion of DDL1 leads to respiratory growth defects. To elucidate the physiological role of DDL1, we screened for genes that, when overexpressed, suppress the respiratory growth defect of the DDL1 deletion mutant. Introduction of COQ8, COQ9, or COQ5, which are involved in coenzyme Q (CoQ) synthesis, using a multicopy vector suppressed the respiratory growth defect of the DDL1 deletion mutant. In contrast, introduction of COQ8 using a multicopy vector did not accelerate the growth of the deletion mutants of TAZ1 or CLD1, which encode an acyltransferase or phospholipase A2, respectively, involved in the remodeling of cardiolipin. These results suggest genetic interactions between the mitochondrial phospholipase A1 gene and the genes involved in CoQ synthesis.ABBREVIATIONS: CoQ: coenzyme Q; CL: cardiolipin; ORF: open reading frame; PA: phosphatidic acid; PC: phosphatidylcholine; PE: phosphatidylethanolamine; PG: phosphatidylglycerol; PLA1: phospholipase A1; iPLA1: intracellular PLA1; PLA2: phospholipase A2.

Keywords: Saccharomyces cerevisiae; coenzyme Q; mitochondria; phospholipase A1; respiration

DOI: https://doi.org/10.1080/09168451.2018.1476124

Mol Cell Neurosci. 2018 May 23. pii: S1044-7431(17)30358-5. [Epub ahead of print]

Depressed mitochondrial function and electron transport Complex II-mediated H2O2 production in the cortex of type 1 diabetic rodents.

Subir Roy Chowdhury, Jelena Djordjevic, Ella Thomson, Darrell R Smith, Benedict C Albensi, Paul Fernyhough.

AIMS: Abnormalities in mitochondrial function under diabetic conditions can lead to deficits in function of cortical neurons and their support cells exhibiting a pivotal role in the pathogenesis of several neurodegenerative disorders, including Alzheimer's disease. We aimed to assess simultaneously mitochondrial respiration rates and membrane potential or H2O2 generation and proteins involved in mitochondrial dynamics, antioxidants and AMPK/SIRT/PGC-1α pathway activity in cortex under diabetic conditions.METHODS: Cortical mitochondria from streptozotocin (STZ)-induced type 1 diabetic rats or mice, and aged-match controls were used for simultaneous measurements of mitochondrial respiration rates and mitochondrial membrane potential (mtMP) or H2O2 using OROBOROS oxygraph and measurements of enzymatic activities by a spectrophotometer. Protein levels in cortical mitochondria and homogenates were determined by Western blotting.
RESULTS: Mitochondrial coupled respiration rates and FCCP-induced uncoupled respiration rates were significantly decreased in mitochondria of STZ-diabetic cortical rats compared to controls. The mtMP in the presence of ADP was significantly depolarized and succinate-dependent respiration rates and H2O2 were significantly diminished in mitochondria of diabetic animals compared to controls, accompanied with reduced expression of CuZn- and Mn-superoxide dismutase. The enzymatic activities of Complex I, II, and IV and protein levels of certain components of Complex I and II, mitofusin 2 (Mfn2), dynamin-related protein 1 (DRP1), P-AMPK, SIRT2 and PGC-1α were significantly diminished in diabetic cortex.
CONCLUSION: Deficits in mitochondrial function, dynamics, and antioxidant capabilities putatively mediated through sub-optimal AMPK/SIRT/PGC-1α signaling, are involved in the development of early sub-clinical neurodegeneration in the cortex under diabetic conditions.

Keywords: Cortex; Diabetes; H(2)O(2); Mitochondrial complexes; Mitochondrial membrane potential; Neuropathy

DOI: https://doi.org/10.1016/j.mcn.2018.05.006

J Neurochem. 2018 May 27.

Mitochondria, lysosomes and dysfunction: their meaning in neurodegeneration.

Matteo Audano, Anja Schneider, Nico Mitro.

In the last decades, lysosomes and mitochondria were considered distinct and physically separated organelles involved in different cellular functions. While lysosomes were thought to exclusively be the rubbish dump of the cell involved in the degradation of proteins and other cell compartments, mitochondria were considered solely involved in the oxidation of energy substrate to get ATP, together with other minor duties. Nowadays, our view of these organelles is profoundly changed since studies demonstrated that mitochondria and lysosome are mutually functional, maintaining proper cell homeostasis. Further, the onset of neurodegenerative diseases (i.e. Parkinson's disease, Alzheimer's disease, lysosomal storage disorders and amyotrophic lateral sclerosis) is tightly linked to mutations in mitochondrial and lysosomal regulators. In this context, mitochondrial dysfunction leads to lysosomal impairment and buildup of autophagy by-products, whereas lysosomal imperfections trigger functional and morphological mitochondrial defects. Here, we provide an updated overview covering recent findings about mitochondria and lysosomal interaction in physiology and pathophysiology, focusing the attention on the molecular mechanism that control their interdependence. This article is protected by copyright. All rights reserved.

DOI: https://doi.org/10.1111/jnc.14471

Anal Biochem. 2018 May 24. pii: S0003-2697(18)30353-1. [Epub ahead of print]

Advanced tools for the analysis of protein phosphorylation in yeast mitochondria.

Corvin Walter, Humberto Gonczarowska-Jorge, Albert Sickmann, René P Zahedi, Chris Meisinger, Oliver Schmidt.

The biochemical analysis of protein phosphorylation in mitochondria lags behind that of cytosolic signaling events. One reason is the poor stability of many phosphorylation sites during common isolation procedures for mitochondria. We present here an optimized, fast protocol for the purification of yeast mitochondria that greatly increases recovery of phosphorylated mitochondrial proteins. Moreover, we describe improved protocols for the biochemical analysis of mitochondrial protein phosphorylation by Zn2+-Phos-tag electrophoresis under both denaturing and - for the first time - native conditions, and demonstrate that they outperform previously applied methods.

Keywords: Blue-native Phos-tag electrophoresis; Mitochondria; Phos-tag electrophoresis; Phosphorylation

DOI: https://doi.org/10.1016/j.ab.2018.05.022