Fueyo, R. | Search bioRxiv

bioRxiv2025

A human-specific regulatory mechanism revealed in a preimplantation model

Stem cell-based human embryo models offer a unique opportunity for functional studies of the human-specific features of development. Here, we genetically and epigenetically manipulate human blastoids, a 3D embryo model of the blastocyst, to investigate the functional impact of HERVK LTR5Hs, a hominoid-specific endogenous retrovirus, on preimplantation development. We uncover a pervasive cis-regulatory contribution of LTR5Hs elements to the hominoid-specific diversification of the blastoids epiblast transcriptome. Many of the nearly 700 LTR5Hs genomic insertions in the human genome are unique to our own species. We show that at least one such human-specific LTR5Hs element is essential for the blastoid-forming potential via enhancing expression of the primate-specific ZNF729 gene, encoding a KRAB zinc finger protein. ZNF729 binds G/C-rich sequences, extremely abundant at gene promoters associated with basic cellular functions, such cell proliferation and metabolism. Surprisingly, despite mediating recruitment of TRIM28, at many of these promoters ZNF729 acts as a transcriptional activator. Together, our results illustrate how recently emerged transposable elements and genes can confer developmentally essential functions in humans.

developmental biology↗

bioRxiv2018

E proteins differentially co-operate with proneural bHLH transcription factors to sharpen neurogenesis

Basic HLH proteins heterodimerize with class I HLH/E proteins to promote transcription. Here we show that E proteins differentially co-operate with proneural bHLH transcription factors sharpening their neurogeneic activity. We find that inhibiting BMP signaling or its target ID2, in the chick embryo spinal cord, impairs the neuronal production from progenitors expressing ATOH1/ASCL1, but less severely that from progenitors expressing NEUROG1/2/PTF1a. We define the mechanisms of this differential response as a dual co-operation of E proteins with proneural proteins. E proteins synergize with bHLH proteins when acting on CAGSTG motifs, thereby facilitating the neurogenic activity of ASCL1/ATOH1 which preferentially bind to such motifs. Conversely, E proteins restrict the strong neurogenic potential of NEUROG1/2 by directly inhibiting their preferential binding to CADATG motifs. Since we find this mechanism to be conserved in corticogenesis, we propose this dual co-operation of E proteins with bHLH proteins as a novel though general feature of their mechanism of action.

developmental biology↗