RING1 links retinoic acid signaling to the early proximal-distal specification of forelimb bud via Meis2 repression (ChIP-Seq). Mus musculus

Polycomb group (PcG) proteins play a pivotal role in silencing of development-related genes and contribute to maintain various stem and precursor cells and regulate their differentiation. However, it is not well understood how PcG factors regulate dynamic and complex morphogenetic processes particularly in mammals. In this study, we focused on proximal-distal (PD) patterning of forelimb bud to elucidate how PcG factors contribute to regulation of morphogenetic processes that depends on developmental signals. Depletion of RING1 proteins, which are common components of both canonical and variant Polycomb repressive complex-1 (PRC1), led to dramatic deficiencies in forelimb formation. By using Ring1-deficient forelimb buds, we revealed the early defects in distal specification, which is due to the functional coupling of RING1 and retinoic acid (RA) signaling. RING1 activity is shown to antagonize with RA signals at Meis2 and likely Meis1, which are superior suppressors of distal formation program, in the prospective distal region of outgrowing forelimb bud. This study exhibits a first example showing how PcG factors interplay with developmental signals to mediate compartmentalization of elongating anlagen by regulating the expression of developmental genes. Overall design: ChIP analysis of mouse E11.5 proximal or distal forelimb buds against anti-RING1B antibody.