Histone deacetylase 1 suppresses Krüppel homolog 1 gene expression and influences juvenile hormone action in <i>Tribolium castaneum</i>.

Abstract

Posttranslational modifications, including acetylation and deacetylation of histones and other proteins, modulate hormone action. In <i>Tribolium castaneum</i> TcA cells, Trichostatin A, a histone deacetylase (HDAC) inhibitor, mimics juvenile hormone (JH) in inducing JH response genes (e.g., <i>Kr-h1</i>), suggesting that HDACs may be involved in JH action. To test this hypothesis, we identified genes coding for HDACs in <i>T. castaneum</i> and studied their function. Knockdown of 12 <i>HDAC</i> genes showed variable phenotypes; the most severe phenotype was detected in insects injected with double-stranded RNA targeting <i>HDAC1</i> (dsHDAC1). The dsHDAC1-injected insects showed arrested growth and development and eventually died. Application of JH analogs hydroprene to <i>T. castaneum</i> larvae and JH III to TcA cells suppressed <i>HDAC1</i> expression. Sequencing of RNA isolated from control and dsHDAC1-injected larvae identified 1,720 differentially expressed genes, of which 1,664 were up-regulated in dsHDAC1-treated insects. The acetylation levels of core histones were increased in TcA cells exposed to dsHDAC1 or JH III. ChIP assays performed using histone H2BK5ac antibodies showed an increase in acetylation in the <i>Kr-h1</i> promoter region of cells exposed to JH III or dsHDAC1. Overexpression or knockdown of <i>HDAC1</i>, <i>SIN3</i>, or both resulted in a decrease or increase in <i>Kr-h1</i> mRNA levels and its promoter activity, respectively. Overexpression of the JH receptor Methoprene tolerant (<i>Met</i>) was unable to induce <i>Kr-h1</i> in the presence of HDAC1 or SIN3. These data suggest that epigenetic modifications influence JH action by modulating acetylation levels of histones and by affecting the recruitment of proteins involved in the regulation of JH response genes.