rd1 Mouse retina shows an imbalance in the activity of cysteine protease cathepsins and their endogenous inhibitor cystatin C.
OBJECTIVE
To compare in vivo levels, spatial localization, and in vitro secretion of cysteine protease cathepsins and cystatin C (cysC) in the retinal degeneration 1 (rd1) mouse model of retinitis pigmentosa and control (wt) mouse retinas.


METHODS
The spatial localization, protein contents, cysC levels and cathepsin-B, -S, and -L activities in wt and rd1 retinas at postnatal (PN) days 2, 7, 14, 21, and 28 were analyzed by immunostaining, spectrophotometry, ELISA, and fluorescence spectrophotometry. The in vitro secretion of cysC and cysteine proteases by PN7 retinal explants into the conditioned medium (RCM) was quantified.


RESULTS
The pigment epithelium, photoreceptors, and inner retinal and ganglion cell layers of both wt and rd1 retinas showed cysC and cathepsin-B labeling. CysC immunostaining was extensive in the optic nerve head fibers. The rd1 explants secreted higher amounts of cysteine protease into the RCM. The protein content in wt and rd1 retinal extracts increased up to PN14, then decreased in rd1 but not in wt. In rd1 extracts at PN14 to -28, cathepsin activity was higher and increased with age, but the cysC level was higher and constant. The ratios of cathepsin activity to cysC (cathepsin-L at PN2 and total, -B, and -L at PN14 to -28) were higher in rd1 extracts.


CONCLUSIONS
Similar localization of both cathepsin-B and cysC in wt and rd1 retinas along with lower proteins and higher cathepsin activity in rd1 retinal extracts and RCM are consistent with their localization in extracellular matrix and a role in physiopathologic remodeling in wt and rd1 retinas.
Ahuja
Satpal
S
Department of Ophthalmology Research, Biomedical Centre B-13, Lund University, Lund, Sweden. sat_pal.ahuja@med.lu.se
Ahuja-Jensen
Poonam
P
Johnson
Leif E
LE
Caffé
A Romeo
AR
Abrahamson
Magnus
M
Ekström
Per A R
PA
van Veen
Theo
T
D000818:Animals; D000831:Animals, Newborn; D002403:Cathepsins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017077:Culture Media, Conditioned; D055316:Cystatin C; D015891:Cystatins / Q000378:metabolism*; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D019084:Fluorescent Antibody Technique, Indirect; D051379:Mice; D008809:Mice, Inbred C3H; D008817:Mice, Mutant Strains; D009924:Organ Culture Techniques; D011480:Protease Inhibitors / Q000378:metabolism*; D012160:Retina / Q000201:enzymology*; D012174:Retinitis Pigmentosa / Q000201:enzymology*; D013050:Spectrometry, Fluorescence
C525031:Cst3 protein, mouse; D017077:Culture Media, Conditioned; D055316:Cystatin C; D015891:Cystatins; D011480:Protease Inhibitors; D002403:Cathepsins