The Pathologic Effect of a Novel Neomorphic Fgf9Y162C Allele Is Restricted to Decreased Vision and Retarded Lens GrowthReport as inadecuate

The Pathologic Effect of a Novel Neomorphic Fgf9Y162C Allele Is Restricted to Decreased Vision and Retarded Lens Growth - Download this document for free, or read online. Document in PDF available to download.

Fibroblast growth factor Fgf signalling plays a crucial role in many developmental processes. Among the Fgf pathway ligands, Fgf9 UniProt: P54130 has been demonstrated to participate in maturation of various organs and tissues including skeleton, testes, lung, heart, and eye. Here we establish a novel Fgf9 allele, discovered in a dominant N-ethyl-N-nitrosourea ENU screen for eye-size abnormalities using the optical low coherence interferometry technique. The underlying mouse mutant line Aca12 was originally identified because of its significantly reduced lens thickness. Linkage studies located Aca12 to chromosome 14 within a 3.6 Mb spanning interval containing the positional candidate genes Fgf9 MGI: 104723, Gja3 MGI: 95714, and Ift88 MGI: 98715. While no sequence differences were found in Gja3 and Ift88, we identified an A→G missense mutation at cDNA position 770 of the Fgf9 gene leading to an Y162C amino acid exchange. In contrast to previously described Fgf9 mutants, Fgf9Y162C carriers were fully viable and did not reveal reduced body-size, male-to-female sexual reversal or skeletal malformations. The histological analysis of the retina as well as its basic functional characterization by electroretinography ERG did not show any abnormality. However, the analysis of head-tracking response of the Fgf9Y162C mutants in a virtual drum indicated a gene-dosage dependent vision loss of almost 50%. The smaller lenses in Fgf9Y162C suggested a role of Fgf9 during lens development. Histological investigations showed that lens growth retardation starts during embryogenesis and continues after birth. Young Fgf9Y162C lenses remained transparent but developed age-related cataracts. Taken together, Fgf9Y162C is a novel neomorphic allele that initiates microphakia and reduced vision without effects on organs and tissues outside the eye. Our data point to a role of Fgf9 signalling in primary and secondary lens fiber cell growth. The results underline the importance of allelic series to fully understand multiple functions of a gene.

Author: Oliver Puk , Gabriele Möller, Arie Geerlof, Kathrin Krowiorz, Nafees Ahmad, Sibylle Wagner, Jerzy Adamski, Martin Hrabé de Ange



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