S-Nitrosylation of mitochondrial caspases

Abstract

Caspase-3 is a cysteine protease located in both the cytoplasm and mitochondrial intermembrane space that is a central effector of many apoptotic pathways. In resting cells, a subset of caspase-3 zymogens is S-nitrosylated at the active site cysteine, inhibiting enzyme activity. During Fas-induced apoptosis, caspases are denitrosylated, allowing the catalytic site to function. In the current studies, we sought to identify the subpopulation of caspases that is regulated by S-nitrosylation. We report that the majority of mitochondrial, but not cytoplasmic, caspase-3 zymogens contain this inhibitory modification. In addition, the majority of mitochondrial caspase-9 is S-nitrosylated. These studies suggest that S-nitrosylation plays an important role in regulating mitochondrial caspase function and that the S-nitrosylation state of a given protein depends on its subcellular localization.

Cardioprotection and mitochondrial S-nitrosation: Effects of S-nitroso-2-mercaptopropionyl glycine (SNO-MPG) in cardiac ischemia–reperfusion injury

“…Indeed, several proteins involved in Ca 2+ and redox signaling are known to be modified by S-nitrosation, including L-type Ca 2+ channels [77], ryanodine receptors [78], thioredoxin [79] hemoglobin [80], mitochondrial K + ATP channels [81,82], TRP channels [83], and caspases [26]. The relative importance of complex I as a mediator of the cardioprotective effects of NO • remains to be determined.…”

“…S-nitros(yl)ation is the reversible NO • -mediated modification of thiols resulting in generation of S-nitrosothiols (SNOs), and is proposed to be a mechanism of NO • -mediated cellular regulation [23][24][25][26]. Recently, we suggested that mitochondrial S-nitrosation is a potential mechanism of NO • signaling in IPC [27], with one particular example being the S-nitrosation and reversible inhibition of mitochondrial respiratory complex I [27,28].…”

Redox-based regulation of signal transduction: Principles, pitfalls, and promises

“…Caspases contain an active site cysteine and a role for NO in preventing caspase activation has been established based upon studies demonstrating that mitochondrial caspase 3 and 9 are S-nitrosylated under basal conditions. In response to a proapoptotic stimulus, such as Fas ligand of tumor necrosis factor-α (TNFα), caspase denitrosylation occurs in association with activation and subsequent execution of the apoptotic pathway [53,133] (Figure 2, box 1). Intriguingly, it has been suggested that Trx (Cys 73-SNO) may exert an antiapoptotic effect by trans-nitrosylation of pro-caspase 3 [111,112].…”

S-Nitrosylation and uncompetitive/fast off-rate (UFO) drug therapy in neurodegenerative disorders of protein misfolding

“…16,27 It has been shown that NO can S-nitrosylate the catalytic cysteine of most or all caspases. [12][13][14][15][16] S-Nitrosylation inhibits protease activity of caspases and consequently prevents apoptotic death in many cell types. All caspases are expressed in cells as catalytically inactive zymogens and encounter proteolytic activation to form active enzymes during apoptosis.…”

“…(a) S-nitrosylation of NMDA receptors can positively influence neuronal survival; 6,8-11 (b) S-nitrosylation of cysteine protease caspase blocks apoptotic cell death; [12][13][14][15][16] (c) S-nitrosylation of parkin (a ubiquitin E3 ligase) and protein-disulfide isomerase (PDI, an endoplasmic reticulum (ER) chaperone) can be injurious by effecting accumulation of misfolded proteins in neurodegenerative diseases such as PD, AD, and other conditions; [17][18][19][20] (d) S-nitrosylation of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) formed in the cytoplasm transduces an apoptotic signal into the nucleus of neuronal cells; 21 and (e) S-nitrosylation of matrix metalloproteinase (MMP)-2/9 leads to a unique extracellular pathway contributing to excitotoxic neuronal cell damage. 22 NMDA Receptor-Mediated Glutamatergic Signaling Pathways Induce Ca 2 þ Influx…”