The Rpd3 histone deacetylase is critical for temperature-mediated morphogenesis and virulence in the human fungal pathogen Histoplasma – HDAC mutant histone acetyl ChIP-seq

Adaptive responses to environmental stimuli are integral to the survival and virulence of microbial pathogens. The thermally dimorphic human fungal pathogen Histoplasma senses temperature to transition between a mold form in soil and a pathogenic yeast in mammalian hosts. The contributions of chromatin-modifying enzymes to the ability of Histoplasma to appropriately respond to temperature have never been explored. Through chemical inhibition and genetics, we determined that the class I histone deacetylase (HDAC) RPD3 is required for normal Histoplasma yeast morphology at 37 ºC. Rpd3 regulated the expression of key morphology-specific genes, including critical virulence factors and transcription factors (TFs), was required for normal DNA-binding activity of yeast-promoting TFs, and influenced histone acetylation levels at the loci of putative pro-filamentation TFs. Furthermore, Rpd3 was required for virulence in a macrophage model of infection. Taken together, Rpd3 is a critical regulatory component that both activates the pathogenesis program and represses the filamentation program to enable thermal dimorphism in Histoplasma. This work uncovers the crucial role that chromatin regulation plays in temperature response of this ubiquitous pathogen. Overall design: ChIP-seq with antibodies to the histone modifications H4K16Ac or H3K9Ac for WT or rpd3 mutant Hisoplasma cells with three bioreps per treatment.

对环境刺激的适应性应答是微生物病原体存活与致病力的核心要素。热双相性人类真菌病原体组织胞浆菌（Histoplasma）可感知温度，在土壤中的菌丝态与哺乳动物宿主内的致病酵母态之间发生形态转换。此前尚无研究探讨染色质修饰酶对组织胞浆菌温度适应性应答能力的调控作用。本研究通过化学抑制与遗传学手段，证实I类组蛋白去乙酰化酶（HDAC）RPD3是组织胞浆菌在37℃下维持正常酵母态形态所必需的因子。Rpd3可调控关键形态特异性基因的表达，包括重要致病因子与转录因子（TFs）；其对酵母形态促进型转录因子的正常DNA结合活性至关重要，同时可影响潜在促菌丝形成转录因子位点的组蛋白乙酰化水平。此外，Rpd3在巨噬细胞感染模型中对病原体的致病力不可或缺。综上，Rpd3是关键的调控因子，可同时激活致病程序并抑制菌丝形成程序，从而介导组织胞浆菌的热双相形态转换。本研究揭示了染色质调控在这一广泛分布的病原体温度应答过程中的核心作用。实验整体设计：对野生型（WT）或rpd3突变型组织胞浆菌细胞，分别使用针对组蛋白修饰H4K16Ac或H3K9Ac的抗体开展染色质免疫共沉淀测序（ChIP-seq），每组处理设置3次生物学重复。