Developmental and tissue expression of Xenopus laevis RPGR.
OBJECTIVE
The present study examined the developmental and tissue expression of the retinitis pigmentosa GTPase regulator (RPGR) gene in Xenopus laevis.


METHODS
The cDNA for X. laevis RPGR (XRPGR) was isolated from adult eye mRNA by reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends. The deduced peptide sequence was aligned with RPGR orthologues. Gene expression was examined by whole-mount in situ hybridization and RT-PCR. The localization of XRPGR in X. laevis photoreceptor cells and XTC-2 cells was determined by immunostaining.


RESULTS
The XRPGR(ex1-19) isoform encodes a protein of 727 amino acids containing an RCC1 domain and a C-terminal isoprenylation anchorage motif. It shares 33% to 41% amino acid identity with human, mouse, and dog RPGR. The C-terminal exon of the alternatively spliced RPGR(ORF15) isoform is also conserved across species. XRPGR is expressed at the earliest stages of X. laevis development and persists into adulthood, where expression is highest in the eye. XRPGR is expressed in presumptive eye fields (stages 18 to 22), becoming largely restricted to the central retina (stages 28 to 40). XRPGR protein colocalizes with beta-tubulin at the X. laevis ciliary axoneme and with gamma-tubulin at centrosomes in XTC-2 cells.


CONCLUSIONS
XRPGR is widely expressed throughout development but shows highest expression after the appearance of the eye primordium and persists in the eye into adulthood. The data are consistent with XRPGR expression in a single microtubular organelle-the centriole or basal body and associated ciliary transitional zone found in modified sensory cilia of photoreceptors and motile cilia.
Shu
Xinhua
X
MRC Human Genetics Unit, Western General Hospital, Edinburgh, United Kingdom.
Zeng
Zhihong
Z
Eckmiller
Marion S
MS
Gautier
Phillipe
P
Vlachantoni
Dafni
D
Manson
Forbes D C
FD
Tulloch
Brian
B
Sharpe
Colin
C
Gorecki
Dariusz C
DC
Wright
Alan F
AF
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D018385:Centrosome / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000032:analysis; D004625:Embryo, Nonmammalian / Q000378:metabolism*; D005136:Eye Proteins / Q000235:genetics* / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D018507:Gene Expression Regulation, Developmental; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics* / Q000378:metabolism; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D020419:Photoreceptor Cells, Vertebrate / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D014404:Tubulin / Q000378:metabolism; D029867:Xenopus Proteins / Q000235:genetics* / Q000378:metabolism; D014982:Xenopus laevis / Q000196:embryology
D018076:DNA, Complementary; D005136:Eye Proteins; D020662:Guanine Nucleotide Exchange Factors; D012333:RNA, Messenger; C099929:RPGR protein, human; D014404:Tubulin; D029867:Xenopus Proteins