Regulatory functions and chromatin loading dynamics of linker histone H1 during endoreplication in .

Eukaryotic DNA replicates asynchronously, with discrete genomic loci replicating during different stages of S phase. larval tissues undergo endoreplication without cell division, and the latest replicating regions occasionally fail to complete endoreplication, resulting in underreplicated domains of polytene chromosomes. Here we show that linker histone H1 is required for the underreplication (UR) phenomenon in salivary glands.

BEN domain protein Elba2 can functionally substitute for linker histone H1 in Drosophila in vivo.

Metazoan linker histones are essential for development and play crucial roles in organization of chromatin, modification of epigenetic states and regulation of genetic activity. Vertebrates express multiple linker histone H1 isoforms, which may function redundantly. In contrast, H1 isoforms are not present in Dipterans, including D.

A view through a chromatin loop: insights into the ecdysone activation of early genes in Drosophila.

The early genes are a key group of ecdysone targets that function at the top of the signaling hierarchy. In the presence of ecdysone, early genes exhibit a highly characteristic rapid and powerful induction that represents a primary response. Multiple isoforms encoded by early genes then coordinate the activation of a larger group of late genes.

The Drosophila juvenile hormone receptor candidates methoprene-tolerant (MET) and germ cell-expressed (GCE) utilize a conserved LIXXL motif to bind the FTZ-F1 nuclear receptor.

Juvenile hormone (JH) has been implicated in many developmental processes in holometabolous insects, but its mechanism of signaling remains controversial. We previously found that in Drosophila Schneider 2 cells, the nuclear receptor FTZ-F1 is required for activation of the E75A gene by JH. Here, we utilized insect two-hybrid assays to show that FTZ-F1 interacts with two JH receptor candidates, the bHLH-PAS paralogs MET and GCE, in a JH-dependent manner.

Molecular Mechanisms of Transcription Activation by Juvenile Hormone: A Critical Role for bHLH-PAS and Nuclear Receptor Proteins.

Juvenile hormone (JH) is responsible for controlling many biological processes. In several insect species JH has been implicated as a key regulator of developmental timing, preventing the premature onset of metamorphosis during larval growth periods. However, the molecular basis of JH action is not well-understood.

Hormonal regulation of the E75 gene in Drosophila: identifying functional regulatory elements through computational and biological analysis.

Drosophila development is regulated by two hormones, 20-hydroxyecdysone (ecdysone) and juvenile hormone. We previously found that expression of the E75 gene is induced by both hormones in cultured S2 cells. E75 occupies over 100 kb of genomic DNA; it has four alternative promoters producing isoforms E75A, E75B, E75C, and E75D.