Gain-of-function mutations of mau/DrAqp3a influence zebrafish pigment pattern formation through the tissue environment [RESEARCH ARTICLE]

Anastasia Eskova, Francois Chauvigne, Hans-Martin Maischein, Moritz Ammelburg, Joan Cerda, Christiane Nüsslein-Volhard, and Uwe Irion

The development of the pigmentation pattern in zebrafish is a tightly regulated process that depends on both the self-organizing properties of pigment cells and extrinsic cues from other tissues. Many of the known mutations that alter the pattern act cell autonomously in pigment cells, and our knowledge about external regulators is limited. Here, we describe several dominant missense mutations in Aquaporin 3a (Aqp3a/mau) that lead to broken stripes and short fins in zebrafish. A loss-of-function allele, generated by CRISPR-Cas9, has no phenotypic consequences, demonstrating that Aqp3a is dispensable for normal development. Strikingly, the pigment cells from dominant mau mutants are capable of forming a wild type pattern when developing in a wild type environment, but the surrounding tissues in the mutants influence pigment cell behaviour and interfere with the patterning process. The mutated amino acid residues in the dominant alleles line the pore surface of Aqp3a and influence pore permeability These results demonstrate an important effect of the tissue environment on pigment cell behaviour and thereby on pattern formation.

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