Abstract
Purpose: :
The objective of this investigation was to determine the germline transmission and retinal expression of a human P23H rhodopsin (RHO) transgene in the progeny of a founder transgenic mini swine from our newly established inbred (SLAcc haplotype) colony.
Methods: :
Fluorescent in situ hybridization (FISH) of chromosome spreads was used to identify the number of integration sites for each of the founder mini swine that were positive by PCR analysis. Sperm from one transgenic founder (53-1), demonstrating early onset of RP, was used to inseminate a domestic wild-type pig and a NIH cc wild-type pig. Progeny were genotyped via PCR for the presence of the human RHO transgene. Nine progeny resulted from the insemination of the domestic pig and six from the NIH mini swine. The offspring from the domestic pig were sacrificed at one day of age. Total RNA from their retinae was utilized for cDNA synthesis, PCR amplification and DNA sequencing to determine the ratio of human vs. pig RHO transcript expression in the retina.
Results: :
FISH analysis showed a single integration site on different chromosomes for each founder. For the two litters produced by 53-1, five of nine piglets from the domestic sow and 2 of 6 piglets from the mini pig sow were positive for the transgene. Transgenic offspring expressed 4-8 copies of the human P23H RHO transcript for each endogenously expressed pig RHO transcript.
Conclusions: :
These data suggested that the human RHO transgene integrated in different genomic regions in the founder transgenic minipigs. The transgene was transmitted to the progeny of 53-1 in Mendelian fashion and expressed in their retinae more abundantly than the endogenous porcine RHO mRNA. Germline transmission of the P23H rhodopsin mutation in this inbred NIH mini swine model provides us with a manageably-sized large animal model of human RP.
Keywords: transgenics/knock-outs • retinal degenerations: cell biology • gene/expression