Phosphorylation of extracellular signal-regulated kinase (ERK) inresponse to arachidonic acid (AA) was rapid and transient, peaking at 1min and disappearing after 3 min, and it was accompanied by an increasein ERK activity in rat neutrophils. We examined the upstream regulationof AA-stimulated ERK activation using one of the following signalingpathway inhibitors to pretreat rat cells: the ERK kinase inhibitorU0126 or PD98059, the Gi/o inhibitor pertussis toxin (PTX),the tyrosine kinase inhibitor genistein, the phosphatidylinositol3-kinase (PI3K) inhibitor wortmannin or LY294002, the Ca2+chelator 1,2-bis(O-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid, or the phospholipase C(PLC) inhibitor U73122. All of these inhibitors attenuated AA-inducedERK activation. Activation of ERK was also effectively attenuated bythe cyclooxygenase and lipoxygenase inhibitor BW755C and by theleukotriene biosynthesis inhibitor MK886, but the cyclooxygenaseinhibitor indomethacin did not attenuate ERK activation. After exposingcells to three distinct protein kinase C (PKC) inhibitors, we foundthat Gö6976 significantly attenuated ERK phosphorylation butpotentiated ERK activity. Neither Gö6983 nor GF109203Xaffected AA-induced responses. These data suggest that the lipoxygenasemetabolite(s) produced mediates AA-stimulated ERK activation and thatthis effect is upstream regulated by PT-sensitive G protein,nonreceptor tyrosine kinase, PI3K, and PLC/Ca2+ signalingpathways in rat neutrophils.
Optic atrophy-1 (OPA1) plays a crucial role in the regulation of mitochondria fusion and participates in maintaining the structural integrity of mitochondrial cristae. Here we elucidate the role of OPA1 cleavage induced by calcium swelling in the presence of Myls22 (an OPA1 GTPase activity inhibitor) and TPEN (an OMA1 inhibitor). The rate of ADP-stimulated respiration was found diminished by both inhibitors, and they did not prevent Ca2+-induced mitochondrial respiratory dysfunction, membrane depolarization, or swelling. L-OPA1 cleavage was stimulated at state 3 respiration; therefore, our data suggest that L-OPA1 cleavage produces S-OPA1 to maintain mitochondrial bioenergetics in response to stress.
more » « less- Award ID(s):
- 2006477
- NSF-PAR ID:
- 10495953
- Publisher / Repository:
- MDPI
- Date Published:
- Journal Name:
- Cells
- Volume:
- 12
- Issue:
- 16
- ISSN:
- 2073-4409
- Page Range / eLocation ID:
- 2017
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Abstract -
Alzheimer’s disease (AD) includes the formation of extracellular deposits comprising aggregated β-amyloid (Aβ) fibers associated with oxidative stress, inflammation, mitochondrial abnormalities, and neuronal loss. There is an associative link between AD and cardiac diseases; however, the mechanisms underlying the potential role of AD, particularly Aβ in cardiac cells, remain unknown. Here, we investigated the role of mitochondria in mediating the effects of Aβ1-40 and Aβ1-42 in cultured cardiomyocytes and primary coronary endothelial cells. Our results demonstrated that Aβ1-40 and Aβ1-42 are differently accumulated in cardiomyocytes and coronary endothelial cells. Aβ1-42 had more adverse effects than Aβ1-40 on cell viability and mitochondrial function in both types of cells. Mitochondrial and cellular ROS were significantly increased, whereas mitochondrial membrane potential and calcium retention capacity decreased in both types of cells in response to Aβ1-42. Mitochondrial dysfunction induced by Aβ was associated with apoptosis of the cells. The effects of Aβ1-42 on mitochondria and cell death were more evident in coronary endothelial cells. In addition, Aβ1-40 and Aβ1-42 significantly increased Ca2+ -induced swelling in mitochondria isolated from the intact rat hearts. In conclusion, this study demonstrates the toxic effects of Aβ on cell survival and mitochondria function in cardiac cells.more » « less
-
more » « less
Abstract Migration is one of the most energy-demanding behaviors observed in birds. Mitochondria are the primary source of energy used to support these long-distance movements, yet how mitochondria meet the energetic demands of migration is scarcely studied. We quantified changes in mitochondrial respiratory performance in the White-crowned Sparrow (
Zonotrichia leucophrys ), which has a migratory and non-migratory subspecies. We hypothesized that the long-distance migratory Gambel’s subspecies (Z. l. gambelii ) would show higher mitochondrial respiratory performance compared to the non-migratory Nuttall’s subspecies (Z. l. nuttalli ). We sampled Gambel’s individuals during spring pre-migration, active fall migration, and a period with no migration or breeding (winter). We sampled Nuttall’s individuals during periods coinciding with fall migration and the winter period of Gambel’s annual cycle. Overall, Gambel’s individuals had higher citrate synthase, a proxy for mitochondrial volume, than Nuttall’s individuals. This was most pronounced prior to and during migration. We found that both OXPHOS capacity (state 3) and basal respiration (state 4) of mitochondria exhibit high seasonal flexibility within Gambel’s individuals, with values highest during active migration. These values in Nuttall’s individuals were most similar to Gambel’s individuals in winter. Our observations indicate that seasonal changes in mitochondrial respiration play a vital role in migration energetics. -
more » « less
Mitochondrion, known as the “powerhouse” of the cell, regulates ion homeostasis, redox state, cell proliferation and differentiation, and lipid synthesis. The inner mitochondrial membrane (IMM) controls mitochondrial metabolism and function. It possesses high levels of proteins that account for ~70% of the membrane mass and are involved in the electron transport chain, oxidative phosphorylation, energy transfer, and ion transport, among others. The mitochondrial matrix volume plays a crucial role in IMM remodeling. Several ion transport mechanisms, particularly K+ and Ca2+, regulate matrix volume. Small increases in matrix volume through IMM alterations can activate mitochondrial respiration, whereas excessive swelling can impair the IMM topology and initiates mitochondria-mediated cell death. The opening of mitochondrial permeability transition pores, the well-characterized phenomenon with unknown molecular identity, in low- and high-conductance modes are involved in physiological and pathological increases of matrix volume. Despite extensive studies, the precise mechanisms underlying changes in matrix volume and IMM structural remodeling in response to energy and oxidative stressors remain unknown. This review summarizes and discusses previous studies on the mechanisms involved in regulating mitochondrial matrix volume, IMM remodeling, and the crosstalk between these processes.
-
more » « less
Abstract Translocator protein 18 kDa (TSPO) is a mitochondrial protein located in the outer membrane and involved in cholesterol translocation, a prerequisite for steroid biosynthesis. TSPO modulation also appears to play a role in other mitochondrial functions, including mitochondrial respiration and cell survival. In the central nervous system, its expression is up‐regulated in neuropathology such as Alzheimer's disease (AD). Previously, we demonstrated that two new TSPO ligands, named 2a and 2b, stimulated pregnenolone synthesis and ATP production in a cellular model of AD overproducing β‐amyloid peptide. The present study aimed to evaluate the impact of the new TSPO ligands on mitochondrial dysfunction in a cellular model of AD‐related tauopathy (human neuroblastoma cells SH‐SY5Y stably overexpressing the P301L‐mutant Tau) presenting mitochondrial impairments, including a decreased ATP synthesis and mitochondrial membrane potential, as well as a decrease in pregnenolone synthesis compared to control cells. The effects of our new ligands were compared with those of TSPO ligands described in the literature (XBD173, SSR‐180,575 and Ro5‐4864). The TSPO ligands 2a and 2b exerted beneficial mitochondrial modulatory effects by increasing ATP levels and mitochondrial membrane potential, paralleled by an increase of pregnenolone levels in mutant Tau cells, as well as in control cells. The compounds 2a and 2b showed effects on mitochondrial activity similar to those obtained with the TSPO ligands of reference. These findings indicate that the new TSPO ligands modulate the mitochondrial bioenergetic phenotype as well as the de novo synthesis of neurosteroids in a cellular model of AD‐related tauopathy, suggesting that these compounds could be potential new therapeutic tools for the treatment of AD.
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/cells12162017
