The Classical Pink-Eyed Dilution Mutation Affects Angiogenic Responsiveness

Abstract

Angiogenesis is the process by which new blood vessels are formed from existing vessels. Mammalian populations, including humans and mice, harbor genetic variations that alter angiogenesis. Angiogenesis-regulating gene variants can result in increased susceptibility to multiple angiogenesis-dependent diseases in humans. Our efforts to dissect the complexity of the genetic diversity that regulates angiogenesis have used laboratory animals due to the availability of genome sequence for many species and the ability to perform high volume controlled breeding. Using the murine corneal micropocket assay, we have observed more than ten-fold difference in angiogenic responsiveness among various mouse strains. This degree of difference is observed with either bFGF or VEGF induced corneal neovascularization. Ongoing mapping studies have identified multiple loci that affect angiogenic responsiveness in several mouse models. In this study, we used F2 intercrosses between C57BL/6J and the 129 substrains 129P1/ReJ and 129P3/J, as well as the SJL/J strain, where we have identified new QTLs that affect angiogenic responsiveness. In the case of AngFq5, on chromosome 7, congenic animals were used to confirm the existence of this locus and subcongenic animals, combined with a haplotype-based mapping approach that identified the pink-eyed dilution mutation as a candidate polymorphism to explain AngFq5. The ability of mutations in the pink-eyed dilution gene to affect angiogenic response was demonstrated using the p-J allele at the same locus. Using this allele, we demonstrate that pink-eyed dilution mutations in Oca2 can affect both bFGF and VEGF-induced corneal angiogenesis.

The albino mutation of tyrosinase alters ocular angiogenic responsiveness

“…This screen identified differences in angiogenic responsiveness resulting from loci on chromosomes 2, 4, 7, 10, 18, X, and Y (Figure 1a). Because we had observed linkage on chromosome 7 in separate studies on bFGF responsiveness [19], we chose this chromosome for further mapping of the loci responsible for differences in angiogenic responsiveness. To do this, we used two strategies, F2 intercross, and recombinant inbred strain cross.…”

Passenger Mutations Confound Interpretation of All Genetically Modified Congenic Mice

“…Several reports have identified 129-derived protein coding variants in for example DAP12 ( Tyrobp ) signaling (McVicar et al, 2002), DNA polymerase iota ( Poli ) (McDonald et al, 2003), beaded filament structural protein 2 ( Bfsp2 ) (Alizadeh et al, 2004; Sandilands et al, 2004), disrupted-in-schizophrenia ( Disc1 ) (Gómez-Sintes et al, 2014; Koike et al, 2006), apolipo-protein A-II ( Apoa2 ) (Su et al, 2009), oculocutaneous albinism II ( Oca2 ) (Rogers et al, 2012), and chromatin licensing and DNA replication factor 1 ( Cdt1 ) (Coulombe et al, 2013). The 129-derived protein coding variant in Bfsp2 and Apoa2 , respectively, results in defects in the lens (Sandilands et al, 2004) and high density lipoprotein (HDL) metabolism (Su et al, 2009).…”

“…This problem has been clearly highlighted back in the mid-nineties (Crawley et al, 1997; Gerlai, 1996; Simpson et al, 1997). Although several reports identify 129-derived protein coding variants in for example DAP12 ( Tyrobp ) signaling (McVicar et al, 2002), DNA polymerase iota ( Poli ) (McDonald et al, 2003), beaded filament structural protein 2 ( Bfsp2 )(**Alizadeh et al, 2004; **Sandilands et al, 2004), disrupted-in-schizophrenia ( Disc1 ) (Gómez-Sintes et al, 2014; Koike et al, 2006), apolipoprotein A-II ( Apoa2 ) (Su et al, 2009), oculocutaneous albinism II ( Oca2 ) (Rogers et al, 2012), and chromatin licensing and DNA replication factor 1 ( Cdt1 ) (Coulombe et al, 2013), this issue has been generally ignored. This issue however re-emerged when Casp1 null mice were found to carry an inactivating passenger mutation in the neighboring Casp11 gene (Kayagaki et al, 2011).…”

Chloride intracellular channel 4 is required for maturation of the cerebral collateral circulation

“…Since there is no in vitro model of collateral formation, we used the aortic ring assay because it encompasses a complete "vascular niche" of interacting cell types and can be harvested from mice of different backgrounds and targeted genes. Background strain is known to affect angiogenic and collaterogenic potential (e.g., 4,19,32), and thus the aortic ring assay controls for any variation in pure C57BL/6 and mixed C57BL/6 ϫ CD1 strains. Average sprout number and length were similar between both Ϫ/Ϫ pial vasculature reveals numerous collaterals (red arrows).…”