Zebrafish adamtsl4 knockout recapitulates key features of human ADAMTSL4-related diseases: a gene involved in extracellular matrix organization, cell junctions and development

Abstract

Loss-of-function mutations in ADAMTSL4, a gene encoding an extracellular matrix-associated protein with incompletely understood biological roles, are linked to autosomal recessive disorders predominantly characterized by lens dislocation. Pupil ectopia, increased intraocular pressure, retinal detachment, cataracts, and skeletal abnormalities are also observed in some patients. To investigate ADAMTSL4 biology and related diseases we established a zebrafish knockout line using CRISPR/Cas9 genome editing. The generated zebrafish model harboured the c.234-351del mutation in adamstsl4, reducing its mRNA levels by 75 % in 6 days post fertilization (dpf) larvae, and predicting to produce an inactive protein (p.(Gln78Hisfs∗127)). Forty percent of F3 knockout larvae (6 dpf) displayed lethal phenotypes characterized by multiple ocular and non-ocular developmental defects, including pericardial, perivitelline and periocular edema, absence of swim bladder, craniofacial malformations and microphthalmia. The remaining 60 % larvae survived and displayed only reduced pupil area, indicating incomplete penetrance of the lethality. Histology revealed extracellular matrix (ECM) and intercellular junctions abnormalities within the cornea, iris, lens, and retinal pigment epithelium (RPE). Adult knockout zebrafish (6 months) presented phenotypes resembling ectopia lentis et pupillae and craniosynostosis, with optical defects in the lens and impaired visual function. ECM and cell junction disorganization in the cornea, lens and RPE were also present in these animals. Transcriptomic analysis revealed disrupted expression of genes involved in development, ECM and cell junctions among other biological processes. These findings show that adamtsl4 recapitulates key features of human ADAMTSL4-related disorders and that this gene is essential for normal ECM structure, cell junctions and embryonic development.

Keywords: ADAMTSL4; Ectopia lentis; Ectopia pupilae; Knockout; Zebrafish.