Differential expression of nitric oxide synthase isoforms in form-deprived chick eyes.
OBJECTIVE
To clarify whether nitric oxide synthase (NOS) is involved in development of myopia, we examined the influence of form deprivation on the expressions of NOS isoform mRNA.


METHODS
NOS isoform cDNAs were amplified from total RNA extracted from control and 7-day-form-deprived chick retina-RPE (retinal pigment epithelium)-choroid, using competitive RT-PCR (reverse-transcription polymerase chain reaction). Each NOS isoform protein was also analyzed by Western blotting and immunohistochemistry.


RESULTS
Expression of inducible NOS (iNOS) mRNA was highest in the control chick retina-RPE-choroid, followed by the expression of brain NOS (bNOS) mRNA. Expression of endothelial NOS (eNOS) mRNA was faint. The iNOS protein level, however, was only slightly higher than the levels of the bNOS and eNOS proteins and was found mainly in the outer part of the photoreceptor layer and inner and outer parts of RPE and choroid. bNOS alone was found in the outer nuclear layer. Although form deprivation reduced the iNOS and bNOS mRNA expressions, only the iNOS protein showed significant reduction.


CONCLUSIONS
All three NOS isoforms were expressed in chick retina-RPE-choroid. Predominant expression of iNOS, instead of bNOS and eNOS, suggested the existence of ocular tissue-specific regulation of the iNOS gene. In addition to differences in expression level, bNOS displayed regional differential expression. Moreover, only iNOS was reduced in response to form deprivation. It is suggested that NOS isoforms may be differentially involved in the mechanisms regulating the posterior eye tissues, including myopic eye growth.
Fujii
S
S
Department of Ophthalmology, Kobe University School of Medicine, Japan.
Honda
S
S
Sekiya
Y
Y
Yamasaki
M
M
Yamamoto
M
M
Saijoh
K
K
D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D002645:Chickens; D002829:Choroid / Q000201:enzymology; D017931:DNA Primers / Q000737:chemistry; D019084:Fluorescent Antibody Technique, Indirect; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D009216:Myopia / Q000201:enzymology* / Q000209:etiology; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D010857:Pigment Epithelium of Eye / Q000201:enzymology*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D012160:Retina / Q000201:enzymology*; D012683:Sensory Deprivation
D017931:DNA Primers; D007527:Isoenzymes; D012333:RNA, Messenger; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III