Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.22 (cdc2)
 8,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Our previous studies in retina on the mechanism for hypoxia-induced cell death suggested activation of a class of calcium-activated proteases known as calpains. This conclusion was based on data showing proteolysis of a calpain substrate alpha-spectrin, autolysis of activated calpain, and reduction of cell damage by calpain inhibitor SJA6017. Less is known about changes in downstream pathways after calpain activation. Thus, the purpose of the present investigation was to measure proteolysis of neuronal cytoskeletal proteins and apoptotic cell signaling factors during hypoxia-induced retinal cell death. Rat retinas were incubated in RPMI medium with glucose and 95% O2/5% CO2 to supply sufficient oxygen for retinal cell survival. Hypoxia was induced with 95% N2/5% CO2 without glucose. Immunoblotting was used to detect activation of calpain and proteolysis of substrates. Amounts of mRNA for calpain 1 and 2 were determined by quantitative PCR. Twelve times more calpain 2 mRNA than calpain 1 was present in retinas. Activation of calpain 2 and production of a calpain-specific alpha-spectrin breakdown product at 150 kDa were confirmed in hypoxic retinas. Further, pro-caspase-3 at 32 kDa was proteolyzed to a fragment at 30 kDa, tau protein was lost, and p35 was proteolyzed to p25 suggesting prolonged activation of cdk5. SJA6017 partially inhibited the production of these fragments. During hypoxia in rat retinas, calpains may be major proteases causing breakdown of neuronal proteins involved in apoptotic cell death. Calpain inhibitor SJA6017 may have potential for testing as a therapeutic agent against retinal pathologies such those caused by glaucoma, although future studies such as testing in in vivo animal models are required.
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PMID:Proteolysis of neuronal cytoskeletal proteins by calpain contributes to rat retinal cell death induced by hypoxia. 1597 93

The purpose of this study was to determine if calpain-induced proteolysis was associated with retinal degeneration or dysfunction in the rat acute ocular hypertensive model. Acute glaucoma was produced by elevation of IOP to 120 mm Hg for 1 hr. Retinal degeneration was evaluated by H&E staining and apoptosis was determined by TUNEL staining in histologic sections of retina. Electroretinogram (ERG) was carried out to evaluate changes in functionality. Activation of calpains was determined by casein zymography and immunoblotting. Total calcium in retina was measured by atomic absorption spectrophotometry. Proteolysis of alpha-spectrin, tau, cdk5, and p35 (a regulator of cdk5) were evaluated by immunoblotting. The thickness of inner plexiform layer (IPL) and inner nuclear layer (INL), and the number of cells in the ganglion cell layer (GCL) decreased after ocular hypertension. Numerous cells in the INL stained positive for TUNEL and some cells in the outer nuclear layer (ONL) showed TUNEL staining. The a-wave in ERG was temporarily decreased after ocular hypertension and then recovered to normal. In contrast, the b-wave was completely lost. Calpains were activated after ocular hypertension. Activation of calpains was associated with increased calcium in retina. Calpain-dependent proteolysis of alpha-spectrin, tau, and p35 were observed in retina after ocular hypertension. The results suggested that increased calcium and subsequent proteolysis by activated calpains was associated with the death of inner retinal cells due to acute ocular hypertension in the rat model. Calpain inhibitors may be candidate drugs for treatment of retinal degeneration and dysfunction resulting from glaucoma.
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PMID:Presence of calpain-induced proteolysis in retinal degeneration and dysfunction in a rat model of acute ocular hypertension. 1652 50