Mechanisms of cyclosporine A toxicity in defined cultures of renal tubule epithelia: A role for cysteine proteases

Wilson, Patricia D.; Hartz, Patricia A.

doi:10.1016/0309-1651(91)90096-2

Cited by 33 publications

(19 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous work has demonstrated a critical role for increased cytosolic [Ca 2ϩ ] f and calpain activity in the process of renal cell injury/death (Wilson and Hartz, 1991;Elliget et al, 1991;Kribben et al, 1994;Edelstein et al, 1995Edelstein et al, , 1996Edelstein et al, , 1997aWaters et al, 1997;Harriman et al, 2002). Recent studies by Chatterjee et al (2001) and McDonald et al (2001) show that calpain inhibitor 1 ameliorates multiple organ failure produced by hemorrhagic shock and renal failure induced by ischemia/reperfusion, indicating that calpains can be important therapeutic targets in the treatment of acute renal failure.…”

Section: Discussionmentioning

confidence: 99%

“…For example, increased calpain activity was observed in rat RPTs subjected to hypoxia and in rabbit RPTs exposed to antimycin A (Edelstein et al, 1995(Edelstein et al, , 1996(Edelstein et al, , 1997aHarriman et al, 2002). Calpain inhibitors have been shown to be cytoprotective in primary RPT cell culture after HgCl 2 or cyclosporin A exposure, and in rat RPTs subjected to hypoxia (Elliget et al, 1991;Wilson and Hartz, 1991;Edelstein et al, 1995Edelstein et al, , 1996. Calpain inhibitors also have exhibited cytoprotective effects in rabbit RPTs exposed to hypoxia/ reoxygenation or a diverse group of toxicants (Waters et al, 1997).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Cytoprotective Properties of Novel Nonpeptide Calpain Inhibitors in Renal Cells

Liu

Harriman

Schnellmann

2002

J Pharmacol Exp Ther

View full text Add to dashboard Cite

Calpains are cytosolic, Ca 2ϩ -activated, neutral cysteine proteases. Rabbit renal proximal tubule (RPT) cells express bothand m-calpain. Although multiple calpain inhibitors protect against RPT cell death, most calpain inhibitors lack specificity, membrane permeability, and/or potency. A group of novel catalytic site-directed calpain inhibitors, including chloroacetic acid NЈ- [6,7-dichloro-4-(4-methoxy-phenyl)-3-oxo-3,4-dihydroquinoxalin-2-yl]hydrazide (SJA7019) and chloroacetic acid NЈ- (6,7-dichloro-4-phenyl-3-oxo-3,4-dihydroquinoxalin-2-yl) hydrazide (SJA7029), were identified to be potent calpain inhibitors in vitro. The goals of this study were to determine the action of these two compounds on 1) RPT calpain activity using fluorescein isothiocyanate-casein zymography, 2) antimycin Ainduced RPT extracellular 45 Ca 2ϩ influx and cell death, and 3) hypoxia/reoxygenation-induced RPT cellular dysfunction and death. The results showed that the SJA compounds inhibited RPT -and m-calpain with equal potency (approximate IC 50 , 30 M) and efficacy, and blocked antimycin A-induced extracellular Ca 2ϩ influx and cell death. In addition, SJA7029 blocked cell death and allowed the recovery of mitochondrial function and active Na ϩ transport in RPTs subjected to hypoxia/reoxygenation. In summary, the SJA compounds 1) were more potent inhibitors of calpains than catalytic site-directed peptide inhibitors in this model, 2) prevented extracellular Ca 2ϩ influx during the late phase of cell death, and 3) are true cytoprotectants and allow recovery of RPT cellular functions after injury.Calpains, cytosolic Ca 2ϩ -activated neutral cysteine proteases, are involved in a variety of cellular functions including the regulation of cytoskeletal structures, cell cycle progression, and cell spreading, adhesion, and migration. There is extensive evidence that calpains play a critical role in cell/tissue/organ injury and death, including renal proximal tubule (RPT) cell injury/death (Bronk and

show abstract

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Cytoprotective Properties of Novel Nonpeptide Calpain Inhibitors in Renal Cells

Liu

Harriman

Schnellmann

2002

J Pharmacol Exp Ther

View full text Add to dashboard Cite

show abstract

“…These results are in agreement with the following observations that the non-calcium-dependent lysosomal cathepsins do not play a role in lethal injury. These observations are that lysosomes are highly resistant to disruption during lethal injury (30), lysosomal proteolysis is inhibited in lethal anoxic injury of rat hepatocytes (27), lysosomal proteolysis is suppressed by ATP depletion (31), and lysosomal cathepsins do not play a role in acute cyclosporine toxicity (7).…”

Section: Discussionmentioning

confidence: 99%

“…Renal brush border membranes are rich in proteases (22) and calpain has been demonstrated in proximal tubules in culture (7) and in both distal and collecting tubules in the rabbit (23,24).…”

Section: Discussionmentioning

confidence: 99%

The role of cysteine proteases in hypoxia-induced rat renal proximal tubular injury.

Edelstein

Wieder

Yaqoob

et al. 1995

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

The role of the lysosomal proteases cathepsins B and L and the calcium-dependent cytosolic protease calpain in hypoxia-induced renal proximal tubular injury was investigated. As compared to normoxic tubules, cathepsin B and L activity, evaluated by the specific fluorescent substrate benzyloxycarbonyl-L-phenylalanyl-L-arginine-7-amido-4-methylcoumarin, was not increased in hypoxic tubules or the medium used for incubation of hypoxic tubules in spite of high lactate dehydrogenase (LDH) release into the medium during hypoxia. These data in rat proximal tubules suggest that cathepsins are not released from lysosomes and do not gain access to the medium during hypoxia. An assay for calpain activity in isolated proximal tubules using the fluorescent substrate N-succinyl-Leu-Tyr-7-amido-4-methylcoumarin was developed. The calcium ionophore ionomycin induced a dose-dependent increase in calpain activity. This increase in calpain activity occurred prior to cell membrane damage as assessed by LDH release. Tubular calpain activity increased signifi'cantly by 7.5 min of hypoxia, before there was significant LDH release, and further increased during 20 min of hypoxia. The cysteine protease inhibitor N-benzyloxycarbonyl-Val-Phe methyl ester (CBZ) markedly decreased LDH release after 20 min of hypoxia and completely prevented the increase in calpain activity during hypoxia. The increase in calpain activity during hypoxia and the inhibitor studies with CBZ therefore supported a role for calpain as a mediator of hypoxia-induced proximal tubular injury.The mechanisms responsible for hypoxia-induced tubular epithelial cell injury and death are controversial (1). Intracellular calcium has been suggested to be important in mediation of this hypoxic injury in renal proximal tubules (2). Our laboratory recently reported that cytosolic free Ca2+ [(Ca2+)i] is significantly increased by 2 min of hypoxia in proximal tubules, and that (Ca2+)i levels at 10 min of hypoxia correlated with subsequent damage at 20 min (3). Thus, prompt increases in (Ca2+), may play an initiating role in hypoxic injury. This conclusion was supported by the protection afforded by prevention of the increase in (Ca2+), (3,4). The mechanisms whereby increases in (Ca2+), lead to cell membrane injury, however, remain to be defined. An increase in (Ca2+)i may activate calcium-dependent enzymes, which could provide a mechanism for cell injury. The increase in (Ca2+)i during hypoxia may activate phospholipase A2 and thus be partly responsible for phospholipid degradation in membranes observed during hypoxia (5). Another potential mechanism for calcium-dependent cell injury is activation of the calciumdependent cytosolic protease calpain. In certain circumstances, proteases have been shown to play a role in cellular injury. For example, studies with cultured fibroblasts and the specific lysosomotropic detergent C12-imidazole demonstrated that cell killing can be caused by activation and/or release into the cytoplasm of cysteine proteases (6). Studies of cysteine p...

show abstract

“…LETTERS cultured with CsA, but can be partially protected from the toxic effects of the drug by either removing Ca2' from the growth medium or co-treating the cultured cells with calcium channel blockers (7).…”

Section: -mentioning

confidence: 99%