G C A T T A C G G C A T genes Article The Polycomb Orthologues in Teleost Fishes and Their Expression in the Zebrafish Model Ludivine Raby, Pamela Völkel, Xuefen Le Bourhis and Pierre-Olivier Angrand * University Lille, CNRS, Inserm, CHU Lille, Centre Oscar Lambret, UMR 9020 - UMR 1277 - Canther - Cancer Heterogeneity, Plasticity and Resistance to Therapies, F-59000 Lille, France;
[email protected] (L.R.);
[email protected] (P.V.);
[email protected] (X.L.B.) * Correspondence:
[email protected]; Tel.: + 33-320-336-222 Received: 21 February 2020; Accepted: 26 March 2020; Published: 27 March 2020 Abstract: The Polycomb Repressive Complex 1 (PRC1) is a chromatin-associated protein complex involved in transcriptional repression of hundreds of genes controlling development and differentiation processes, but also involved in cancer and stem cell biology. Within the canonical PRC1, members of Pc/CBX protein family are responsible for the targeting of the complex to specific gene loci. In mammals, the Pc/CBX protein family is composed of five members generating, through mutual exclusion, different PRC1 complexes with potentially distinct cellular functions. Here, we performed a global analysis of the cbx gene family in 68 teleost species and traced the distribution of the cbx genes through teleost evolution in six fish super-orders. We showed that after the teleost-specific whole genome duplication, cbx4, cbx7 and cbx8 are retained as pairs of ohnologues. In contrast, cbx2 and cbx6 are present as pairs of ohnologues in the genome of several teleost clades but as singletons in others.