Developmental regulatory system of ocular‐side‐specific asymmetric pigmentation in flounder: Critical role of retinoic acid signaling. Issue 3 (10th February 2020)

• Record Type: Journal Article
• Authors: Chen, Qiran; Sato, Kota; Yokoi, Hayato; Suzuki, Tohru
• Is Part Of: Journal of experimental zoology. Volume 334:Issue 3(2020)
• Page Start: 156
• Page End: 167
• Publication Date: 2020-02-10
• Subjects: asymmetry -- BMS493 -- chromatoblast -- chromatophore -- flounder -- gch2 -- retinoic acid -- Sox10; Developmental biology -- Periodicals; Evolution (Biology) -- Periodicals; Molecular evolution -- Periodicals; Zoology -- Periodicals; Evolution, Molecular -- Periodicals; Developmental Biology -- Periodicals; Zoology -- Periodicals; 591
• DOI: 10.1002/jez.b.22934
• Languages: English
• ISSNs: 1552-5007

Abstract

Abstract: The body color of the Pleuronectiformes is bilaterally asymmetric between right and left halves, with a dark ocular‐side and a white blind‐side. This body color asymmetry develops by restricted differentiation of melanophores and xanthophores on the ocular‐side during metamorphosis, accompanied by migration of one eye to the future ocular‐side. In this study, we elucidated the developmental regulatory system of this lateralized pigmentation. We found that in flounder, Sox10‐positive chromatophore progenitors appear bilaterally both in the ocular‐ and blind‐side skin of metamorphosing larvae, and that those arriving at the ocular‐side skin differentiate into gch2 ‐positive chromatoblasts and then chromatophores. Transient exposure of metamorphosing larvae to retinoic acid (RA)‐induced progenitors on the blind‐side to differentiate into gch2 ‐positive chromatoblasts. On the contrary, exposure to an RA receptor antagonist, BMS493, suppressed the differentiation of gch2 ‐positive chromatoblasts on the ocular‐side. Thus, we demonstrated that RA is essential for flounder chromatophore progenitors to differentiate into chromatoblasts. At the time of chromatoblast differentiation on the ocular‐side, cyp26b1, which inactivates RA, was upregulated on the blind‐side skin compared with the ocular‐side. Therefore, we surmise that ocular‐side‐specific pigmentation is regulated by the inhibition of RA‐signaling by cyp26b1 on the blind‐side. Abstract : Both ocular‐ and blind‐side skin of metamorphosing flounder larvae has potential to be pigmented, since Sox10‐positive chromatophore progenitors appear on both laterals sides. The progenitors require retinoic acid (RA) for differentiating to chromatoblasts, while cyp26b1 is expressed at blind‐side, suppressing the differentiation of progenitors. This results in ocular‐side‐specific pigmentation, unique to flounder. Research Highlights: We show flounder asymmetric pigmentation mechanism. Sox10+ progenitors appear in both sides of skin. Progenitor requires RA to become gch2 + chromatoblast. cyp26b1 on blind‐side inhibits RA signaling to enable asymmetric pigmentation.