CHD1 Motor Protein Is Required for Deposition of Histone Variant H3.3 into Chromatin in Vivo

Abstract

The organization of chromatin affects all aspects of nuclear DNA metabolism in eukaryotes. H3.3 is an evolutionarily conserved histone variant and a key substrate for replication-independent chromatin assembly. Elimination of chromatin remodeling factor CHD1 in Drosophila embryos abolishes incorporation of H3.3 into the male pronucleus, renders the paternal genome unable to participate in zygotic mitoses, and leads to the development of haploid embryos. Furthermore, CHD1, but not ISWI, interacts with HIRA in cytoplasmic extracts. Our findings establish CHD1 as a major factor in replacement histone metabolism in the nucleus and reveal a critical role for CHD1 in the earliest developmental instances of genome-scale, replication-independent nucleosome assembly. Furthermore, our results point to the general requirement of adenosine triphosphate (ATP)-utilizing motor proteins for histone deposition in vivo.H istone-DNA interactions constantly change during various processes of DNA metabolism. Recent studies have highlighted the importance of histone variants, such as H3.3, CENP-A (centromere protein A), or H2A.Z, in chromatin dynamics (1, 2). Incorporation of replacement histones into chromatin occurs throughout the cell cycle, whereas nucleosomes containing canonical histones are assembled exclusively during DNA replication. A thorough understanding of the replication-independent mechanisms of chromatin assembly, however, is lacking.In vitro, chromatin assembly requires the action of histone chaperones and adenosine triphosphate (ATP)-utilizing factors (3). Histone chaperones may specialize for certain histone variants. For example, H3.3 associates with a complex containing HIRA, whereas canonical H3 is in a complex with CAF-1 (chromatin assembly factor 1) (4). The molecular motors known to assemble nucleosomes are ACF (ATP-utilizing chromatin assembly and remodeling factor), CHRAC (chromatin accessibility complex), and RSF (nucleosome-remodeling and spacing factor), which contain the Snf2 family member ISWI as the catalytic subunit (5-7), and CHD1, which belongs to the CHD subfamily of Snf2-like adenosine triphosphatases (ATPases) (8). These factors have not been shown to mediate deposition of histones in vivo. We previously demonstrated that CHD1, together with the chaperone NAP-1, assembles nucleosome arrays from DNA and histones in vitro (9). Here, we investigated the role of CHD1 in chromatin assembly in vivo in Drosophila.We generated Chd1 alleles by P elementmediated mutagenesis (Fig. 1A) (10). Two exci- 2] with Df(2L)Exel7014 affect both copies of the Chd1 gene only (Fig. 1B). We also identified a single point mutation that results in premature translation termination of Chd1 (Q1394*) in a previously described lethal allele, l(2)23Cd[A7-4] (11). Hence, l(2)23Cd[A7-4] was renamed Chd1 [3].sions, Df(2L)Chd1[1] and Df(2L)Chd1[2], deleted fragments of the Chd1 gene and fragments of unrelated adjacent genes. Heterozygous combinations, however, of Chd1[1] or Chd1[Analysis of Western blots of embryos from heterozyg...

Use of biotinylated plasmid DNA as a surrogate for HSV DNA to identify proteins that repress or activate viral gene expression

“…The consequence of binding is not clear. It has been demonstrated that CHD1 is required for the deposition of Histone H3.3 into chromatin in vivo and ubiquitination of histone H2B (80,81). CHD1 could in fact activate transcription rather than repress it.…”

Myogenic transcriptional activation of MyoD mediated by replication-independent histone deposition

“…S1C). Unexpectedly, the expression of CHD1, another chromatin remodeling factor implicated in H3.3 deposition (10), was decreased at the onset of differentiation (Fig. 1B and Fig.…”

“…As for nontranscriptional function, H3.3 or HIRA contributes to mammalian sex chromosome inactivation (7), germline cell development (8), and fertilization (9) through a massive genome-wide nucleosome assembly. Chromatin remodeling factor CHD1, which belongs to the chromodomain family of SNF2-like adenosine triphosphatases, is also responsible for H3.3 incorporation into the male pronucleus, presumably in couple with HIRA (10). Besides, HIRA is involved in the formation of senescence-associated heterochromatic foci (SAHF) (11) and the maintenance of gene silencing (12)(13)(14).…”

The double face of the histone variant H3.3

“…The remodeling factor named chromodomain helicase DNA-binding protein 1 (CHD1) physically associates with HIRA to mediate massive H3.3 incorporation into male chromatin during the decondensation of the Drosophila sperm DNA upon fertilization ( Figure 3) [73]. Whether this chromatin-remodeling factor is required for other HIRA complex-mediated H3.3 depositions is an open issue.…”