Abstract
The purpose of the present study was to determine if proteolysis by the calcium-dependent enzyme calpains (EC 3.4.22.17) contributed to retinal cell death in a rat model of photoreceptor degeneration induced by intraperitoneal injection of N-methyl-N-nitrosourea (MNU). Retinal degeneration was evaluated by H&E staining, and cell death was determined by TUNEL assay. Total calcium in retina was measured by atomic absorption spectrophotometry. Activation of calpains was determined by casein zymography and immunoblotting. Proteolysis of α-spectrin and p35 (regulator of Cdk5) were evaluated by immunoblotting. Calpain inhibitor SNJ-1945 was orally administrated to MNU-treated rats to test drug efficacy. MNU decreased the thickness of photoreceptor cell layer, composed of the outer nuclear layer (ONL) and outer segment (OS). Numerous cells in the ONL showed positive TUNEL staining. Total calcium was increased in retina after MNU. Activation of calpains and calpain-specific proteolysis of α-spectrin were observed after MNU injection. Oral administration of SNJ-1945 to MNU-treated rats showed a significant protective effect against photoreceptor cell loss, confirming involvement of calpains in photoreceptor degeneration. Conversion of p35 to p25 was well correlated with calpain activation, suggesting prolonged activation of Cdk5/p25 as a possible downstream mechanism for MNU-induced photoreceptor cell death. SNJ-1945 reduced photoreceptor cells death, even though MNU is one of the most severe models of photoreceptor cell degeneration. Oral calpain inhibitor SNJ-1945 may be a candidate for testing as a medication against retinal degeneration in retinitis pigmentosa.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 39-48 |
| Number of pages | 10 |
| Journal | Experimental Neurology |
| Volume | 204 |
| Issue number | 1 |
| DOIs | |
| State | Published - Mar 2007 |
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Keywords
- α-Spectrin
- Calcium
- Calpain
- Cdk5/p25
- MNU
- Retinitis pigmentosa
- SNJ-1945
ASJC Scopus subject areas
- Neurology
- Neuroscience(all)
Cite this
Contribution of calpains to photoreceptor cell death in N-methyl-N-nitrosourea-treated rats. / Oka, Takayuki; Nakajima, Takeshi; Tamada, Yoshiyuki; Shearer, Thomas (Tom); Azuma, Mitsuyoshi.
In: Experimental Neurology, Vol. 204, No. 1, 03.2007, p. 39-48.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Contribution of calpains to photoreceptor cell death in N-methyl-N-nitrosourea-treated rats
AU - Oka, Takayuki
AU - Nakajima, Takeshi
AU - Tamada, Yoshiyuki
AU - Shearer, Thomas (Tom)
AU - Azuma, Mitsuyoshi
PY - 2007/3
Y1 - 2007/3
N2 - The purpose of the present study was to determine if proteolysis by the calcium-dependent enzyme calpains (EC 3.4.22.17) contributed to retinal cell death in a rat model of photoreceptor degeneration induced by intraperitoneal injection of N-methyl-N-nitrosourea (MNU). Retinal degeneration was evaluated by H&E staining, and cell death was determined by TUNEL assay. Total calcium in retina was measured by atomic absorption spectrophotometry. Activation of calpains was determined by casein zymography and immunoblotting. Proteolysis of α-spectrin and p35 (regulator of Cdk5) were evaluated by immunoblotting. Calpain inhibitor SNJ-1945 was orally administrated to MNU-treated rats to test drug efficacy. MNU decreased the thickness of photoreceptor cell layer, composed of the outer nuclear layer (ONL) and outer segment (OS). Numerous cells in the ONL showed positive TUNEL staining. Total calcium was increased in retina after MNU. Activation of calpains and calpain-specific proteolysis of α-spectrin were observed after MNU injection. Oral administration of SNJ-1945 to MNU-treated rats showed a significant protective effect against photoreceptor cell loss, confirming involvement of calpains in photoreceptor degeneration. Conversion of p35 to p25 was well correlated with calpain activation, suggesting prolonged activation of Cdk5/p25 as a possible downstream mechanism for MNU-induced photoreceptor cell death. SNJ-1945 reduced photoreceptor cells death, even though MNU is one of the most severe models of photoreceptor cell degeneration. Oral calpain inhibitor SNJ-1945 may be a candidate for testing as a medication against retinal degeneration in retinitis pigmentosa.
AB - The purpose of the present study was to determine if proteolysis by the calcium-dependent enzyme calpains (EC 3.4.22.17) contributed to retinal cell death in a rat model of photoreceptor degeneration induced by intraperitoneal injection of N-methyl-N-nitrosourea (MNU). Retinal degeneration was evaluated by H&E staining, and cell death was determined by TUNEL assay. Total calcium in retina was measured by atomic absorption spectrophotometry. Activation of calpains was determined by casein zymography and immunoblotting. Proteolysis of α-spectrin and p35 (regulator of Cdk5) were evaluated by immunoblotting. Calpain inhibitor SNJ-1945 was orally administrated to MNU-treated rats to test drug efficacy. MNU decreased the thickness of photoreceptor cell layer, composed of the outer nuclear layer (ONL) and outer segment (OS). Numerous cells in the ONL showed positive TUNEL staining. Total calcium was increased in retina after MNU. Activation of calpains and calpain-specific proteolysis of α-spectrin were observed after MNU injection. Oral administration of SNJ-1945 to MNU-treated rats showed a significant protective effect against photoreceptor cell loss, confirming involvement of calpains in photoreceptor degeneration. Conversion of p35 to p25 was well correlated with calpain activation, suggesting prolonged activation of Cdk5/p25 as a possible downstream mechanism for MNU-induced photoreceptor cell death. SNJ-1945 reduced photoreceptor cells death, even though MNU is one of the most severe models of photoreceptor cell degeneration. Oral calpain inhibitor SNJ-1945 may be a candidate for testing as a medication against retinal degeneration in retinitis pigmentosa.
KW - α-Spectrin
KW - Calcium
KW - Calpain
KW - Cdk5/p25
KW - MNU
KW - Retinitis pigmentosa
KW - SNJ-1945
UR - http://www.scopus.com/inward/record.url?scp=33847384203&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33847384203&partnerID=8YFLogxK
U2 - 10.1016/j.expneurol.2006.09.011
DO - 10.1016/j.expneurol.2006.09.011
M3 - Article
C2 - 17069801
AN - SCOPUS:33847384203
VL - 204
SP - 39
EP - 48
JO - Experimental Neurology
JF - Experimental Neurology
SN - 0014-4886
IS - 1
ER -