Cloning and high expression of rabbit FKBP25 in cornea

Rabbit 25 kDa FK-506/rapamycin binding protein (FKBP25) cDNA was isolated during a screening of rabbit corneal endothelial cDNA library. The cDNA clone was a 955 bp fragment with a 670 bp open reading frame and a 285 bp 3' non-coding region. The cDNA and deduced amino acid sequences were 91.7 and 96.4% identical, respectively, to previously reported human FKBP25B sequences. The lysine-rich region KK(X)7KK(X)26KKKK, which plays an important role in nuclear translocation in rabbit FKBP25, was recognized. Reverse transcription-polymerase chain reaction (RT-PCR) amplification of rabbit FKBP25 and FKBP12 in selected rabbit organs, including total cornea, showed higher expressions in cornea, retina, cerebrum and cerebellum than other compared tissues. RT-PCR amplification in rabbit cultured corneal cells showed expressions in all cultured corneal epithelial, stromal, endothelial, and especially in SV40-adenovirus vector-immortalized epithelial cells. The higher expressions of FKBP25 and FKBP12 suggest significant roles for FKBPs in those tissues.