Expression of human Cfdp1 gene in Drosophila reveals new insights into the function of the evolutionarily conserved BCNT protein family

Abstract

The Bucentaur (BCNT) protein family is widely distributed in eukaryotes and is characterized by a highly conserved C-terminal domain. This family was identified two decades ago in ruminants, but its role(s) remained largely unknown. Investigating cellular functions and mechanism of action of BCNT proteins is challenging, because they have been implicated in human craniofacial development. Recently, we found that YETI, the D. melanogaster BCNT, is a chromatin factor that participates to H2A.V deposition. Here we report the effects of in vivo expression of CFDP1, the human BCNT protein, in Drosophila melanogaster. We show that CFDP1, similarly to YETI, binds to chromatin and its expression results in a wide range of abnormalities highly reminiscent of those observed in Yeti null mutants. This indicates that CFDP1 expressed in flies behaves in a dominant negative fashion disrupting the YETI function. Moreover, GST pull-down provides evidence indicating that 1) both YETI and CFDP1 undergo homodimerization and 2) YETI and CFDP1 physically interact each other by forming inactive heterodimers that would trigger the observed dominant-negative effect. Overall, our findings highlight unanticipated evidences suggesting that homodimerization mediated by the BCNT domain is integral to the chromatin functions of BCNT proteins.

The human Cranio Facial Development Protein 1 (Cfdp1) gene encodes a protein required for the maintenance of higher-order chromatin organization

“…This could be due to the in vivo formation of inactive YETI-CFDP1 heterodimers (Fig. 4F), a result that corroborates our previous in vitro findings29.…”

“…Our previous results suggest that when CFDP1 is expressed in wild-type fruit flies, it can physically interact with YETI to form inactive heterodimers; this would result in an overall depletion of functional YETI with a consequent disruption of chromatin organization and individual viability29. To test whether YETI overexpression may affect cell behavior in human cells, we transiently transfected HeLa cells with Flag- Yeti and V5- Cfdp1 cDNA constructs.…”

“…V5-CFDP1 and Flag-YETI plasmid are described in our previous papers2429. The constructs pCS2-5xMyc-Arp6, pcDNA3-HA-H2A.Z and pcDNA3-HA-SRCAP were described in ref.…”

“…More recently, it has been shown that the CFDP1 protein expressed in wild-type Drosophila melanogaster is able to bind salivary gland polytene chromosomes, strongly affecting chromatin organization and H2Av deposition in a dominant-negative fashion29. In addition to its possible role in chromatin remodeling, CFDP1 may also have autonomous functions in transcriptional regulation, as suggested by its interactions with SMAD3 and Ewings Sarcoma (EWS) proteins, which are involved in the modulation of transcription30.…”

ATPase SRCAP is a new player in cell division, uncovering molecular aspects of Floating-Harbor syndrome

“…It maps to chromosome 16p11.2 and encodes the ATPase SRCAP, the core catalytic subunit of the homonymous multiprotein chromatin-remodeling complex in humans. The SRCAP complex is member of the evolutionarily conserved INO80 family of ATP-dependent chromatin remodeling complexes (12,13) and contains a dozen subunits (12)(13)(14)(15)(16)(17)(18). The primary function of the SRCAP complex is to catalyze the incorporation of H2AZ-H2B dimers into nucleosomes (19,20).…”