Characterization and localization of the rabbit ocular calcitonin gene-related peptide (CGRP)-receptor component protein (RCP).
OBJECTIVE
To determine whether the calcitonin gene-related peptide (CGRP) receptor component protein (RCP), a novel signal transduction molecule, is required for CGRP signaling in the eye and to determine potential ocular sites of CGRP action.


METHODS
The cDNA for the rabbit ocular RCP homologue was cloned using a combination of reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE). Function of the rabbit ocular RCP was assessed using a sensitive oocyte-based assay, which utilizes the protein kinase A (PKA)-sensitive cystic fibrosis transmembrane conductance regulator (CFTR) as a sensor of cAMP formation. RCP expression in the rabbit eye was localized using immunohistochemistry.


RESULTS
A 2063-bp cDNA for the rabbit ocular RCP was cloned and sequenced. Expression of the rabbit RCP cDNA confers CGRP responsiveness in a sensitive oocyte-based assay. Antisense oligonucleotides made to the ocular RCP abolishes CGRP responsiveness of ciliary body and iris mRNA in the oocyte-CFTR assay. Localization of RCP protein in the rabbit eye using immunohistochemistry demonstrated RCP immunoreactivity in the ciliary body and iris blood vessels, as well as in layers of the ciliary epithelium.


CONCLUSIONS
The rabbit ocular RCP appears to be required for signal transduction at ocular CGRP receptors and is localized to sites previously reported to bind CGRP, which affect intraocular pressure and neurogenic inflammation.
Rosenblatt
M I
MI
Department of Biochemistry and Molecular Biology, University of Miami School of Medicine, Florida 33101, USA.
Dahl
G P
GP
Dickerson
I M
IM
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002924:Ciliary Body / Q000737:chemistry*; D003001:Cloning, Molecular; D004247:DNA / Q000032:analysis; D007124:Immunoenzyme Techniques; D007498:Iris / Q000737:chemistry*; D007908:Lens, Crystalline / Q000737:chemistry*; D008297:Male; D008969:Molecular Sequence Data; D016376:Oligonucleotides, Antisense; D011817:Rabbits; D018015:Receptors, Calcitonin Gene-Related Peptide / Q000032:analysis* / Q000235:genetics / Q000502:physiology; D012160:Retina / Q000737:chemistry*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
D016376:Oligonucleotides, Antisense; D018015:Receptors, Calcitonin Gene-Related Peptide; D004247:DNA