Hippo signalling pathway found to regulate cuticle pigmentation and dopamine metabolism in Drosophila

Researchers led by Shelley B. Gibson, Samantha L. Deal, and colleagues have published findings in PLOS Genetics showing that the Hippo signalling pathway plays a previously underappreciated role in regulating cuticle pigmentation in Drosophila melanogaster. The Hippo pathway is an evolutionarily conserved signalling cascade studied primarily for its role in controlling organ size and suppressing tumour growth; this study extends its functional repertoire into pigmentation biology.

The work demonstrates that disruption of Hippo signalling alters the activity of key enzymes in the dopamine biosynthesis pathway — specifically Tyrosine hydroxylase (TH) and Dopa decarboxylase (Ddc) — which are required to produce the dopamine precursors that feed melanin synthesis in the insect cuticle. Authors include Hongjie Li, Shinya Yamamoto, Hyung-Lok Chung, and collaborators across multiple institutions.

Because the Hippo pathway is conserved across animals, the findings raise questions for researchers about whether analogous connections between Hippo signalling and dopamine or pigmentation biology exist in other species. The dopamine biosynthesis enzymes implicated — TH and Ddc — have vertebrate homologues with roles in neurology and metabolism, making this a study of potential comparative interest to researchers in developmental and evolutionary biology as well as those studying Hippo-pathway cancers. The paper does not address clinical applications and the findings are in an invertebrate model system.