Distinct DNA-binding modes of Sp8 and Sp6 shape a hierarchical regulatory network in limb ectoderm

ABSTRACT: Sp8 and Sp6 are closely related transcription factors expressed in the limb ectoderm, where they control proximo-distal and dorso-ventral patterning, yet their direct targets and molecular mechanisms have remained unclear. Combining genome-wide chromatin occupancy with transcriptomic profiling in vivo, we identify shared and specific targets and reconstruct the Sp8/Sp6 gene regulatory network, establishing Sp8 as its dominant, hierarchical node. Mechanistically, the two factors diverge: Sp8 binds DNA directly at canonical GC-rich Sp motifs, regulating targets including Fgf8 and Sp6 itself, whereas Sp6 acts as a transcriptional cofactor. Via indirect binding to AT-rich motifs through Dlx, both cooperatively regulate limb-patterning pathways, including Wnt, FGF, TGF-β/BMP, and Notch. Biochemical assays confirm that both form homo- and heterodimers and interact with Dlx5 through their zinc-finger domains. Together, these findings reveal how Sp8 and Sp6 orchestrate AER formation and dorso-ventral patterning, providing a mechanistic framework for congenital limb malformations such as split-hand/foot malformation.

ORGANISM(S): Mus musculus

PROVIDER: GSE300852 | GEO | 2026/06/24

REPOSITORIES: GEO