Elevated TGFβ signaling contributes to ocular anterior segment dysgenesis in Col4a1 mutant mice

Highlights

• Col4a1 mutant mice have anterior segment dysgenesis and other ocular defects affecting lens and retina.

• TGFβ signaling is elevated in developing anterior segments from Col4a1 mutant mice.

• Genetically reducing TGFβ signaling using Tgfb1 or Tgfb2 mutations partially rescues ocular defects in Col4a1 mutant mice.

• Pharmacologically promoting a1a1a2(IV) secretion or reducing TGFβ signaling ameliorates ocular defects in Col4a1 mutant mice.

• TGFβ1 and TGFβ2 differentially contribute to the ocular defects observed in Col4a1 mutant mice.

Abstract

Ocular anterior segment dysgenesis (ASD) refers to a collection of developmental disorders affecting the anterior structures of the eye. Although a number of genes have been implicated in the etiology of ASD, the underlying pathogenetic mechanisms remain unclear. Mutations in genes encoding collagen type IV alpha 1 (COL4A1) and alpha 2 (COL4A2) cause Gould syndrome, a multi-system disorder that often includes ocular manifestations such as ASD and glaucoma. COL4A1 and COL4A2 are abundant basement membrane proteins that provide structural support to tissues and modulate signaling through interactions with other extracellular matrix proteins, growth factors, and cell surface receptors. In this study, we used a combination of histological, molecular, genetic and pharmacological approaches to demonstrate that altered TGFβ signaling contributes to ASD in mouse models of Gould syndrome. We show that TGFβ signaling was elevated in anterior segments from Col4a1 mutant mice and that genetically reducing TGFβ signaling partially prevented ASD. Notably, we identified distinct roles for TGFβ1 and TGFβ2 in ocular defects observed in Col4a1 mutant mice. Importantly, we show that pharmacologically promoting type IV collagen secretion or reducing TGFβ signaling ameliorated ocular pathology in Col4a1 mutant mice. Overall, our findings demonstrate that altered TGFβ signaling contributes to COL4A1-related ocular dysgenesis and implicate this pathway as a potential therapeutic target for the treatment of Gould syndrome.