Department of Clinical Pharmacy and Translational Science, College of Pharmacy, University of Tennessee Health Sciences Center, Memphis, Tennessee, USA.
Department of Molecular Immunology and Biochemistry, College of Graduate Health Sciences, University of Tennessee Health Sciences Center, Memphis, Tennessee, USA.
mSphere. 2019 Feb 6;4(1):e00715-18. doi: 10.1128/mSphere.00715-18.
Calcium is a critically important secondary messenger of intracellular signal transduction in eukaryotes but must be maintained at low levels in the cytoplasm of resting cells to avoid toxicity. This is achieved by several pumps that actively transport excess cytoplasmic Ca out of the cell across the plasma membrane and into other intracellular compartments. In fungi, the vacuole serves as the major storage site for excess Ca, with two systems actively transporting cytoplasmic calcium ions into the vacuole. The H/Ca exchanger, Vcx1p, harnesses the proton-motive force across the vacuolar membrane (generated by the V-ATPase) to drive Ca transport, while the P-type ATPase Pmc1p uses ATP hydrolysis to translocate Ca into the vacuole. Ca-dependent signaling is required for the prevalent human fungal pathogen to endure exposure to the azole antifungals and to cause disease within the mammalian host. The purpose of this study was to determine if the Pmc1p or Vcx1p Ca pumps are required for pathogenicity and if these pumps impact antifungal resistance. Our results indicate that Pmc1p is required by to transition from yeast to hyphal growth, to form biofilms , and to cause disease in a mouse model of disseminated infection. Moreover, loss of Pmc1p function appears to enhance azole tolerance in a temperature-dependent manner. Maintenance of Ca homeostasis is important for fungal cells to respond to a multitude of stresses, as well as antifungal treatment, and for virulence in animal models. Here, we demonstrate that a P-type ATPase, Pmc1p, is required for to respond to a variety of stresses, affects azole susceptibility, and is required to sustain tissue invasive hyphal growth and to cause disease in a mouse model of disseminated infection. Defining the mechanisms responsible for maintaining proper Ca homeostasis in this important human pathogen can ultimately provide opportunities to devise new chemotherapeutic interventions that dysregulate intracellular signaling and induce Ca toxicity.
钙是真核细胞内信号转导的重要二级信使，但在静息细胞的细胞质中必须保持低水平，以避免毒性。这是通过几种泵来实现的，这些泵将细胞质中多余的钙主动运输穿过质膜并进入其他细胞内隔室。在真菌中，液泡是多余钙的主要储存场所，有两个系统将细胞质中的钙离子主动运输到液泡中。H/Ca 交换器 Vcx1p 利用质膜上的质子动力势（由 V-ATPase 产生）来驱动 Ca 运输，而 P 型 ATP 酶 Pmc1p 则利用 ATP 水解将 Ca 转运到液泡中。Ca 依赖性信号对于普遍存在的人类真菌病原体 来说是必需的，以耐受唑类抗真菌药物的暴露，并在哺乳动物宿主内引起疾病。本研究的目的是确定 Pmc1p 或 Vcx1p Ca 泵是否是 致病性所必需的，以及这些泵是否影响抗真菌耐药性。我们的结果表明，Pmc1p 是 从酵母向菌丝生长、形成生物膜 和在播散性感染的小鼠模型中引起疾病所必需的。此外，Pmc1p 功能的丧失似乎以温度依赖的方式增强了 对唑类药物的耐受性。钙稳态的维持对于真菌细胞应对多种应激、抗真菌治疗以及在动物模型中的毒力都很重要。在这里，我们证明 P 型 ATP 酶 Pmc1p 是 对各种应激的反应所必需的，影响唑类药物的敏感性，并且是维持组织侵袭性菌丝生长和在播散性感染的小鼠模型中引起疾病所必需的。确定维持这种重要的人类病原体中适当钙稳态的机制最终可以为设计新的化疗干预措施提供机会，这些干预措施可以使细胞内信号失调并诱导 Ca 毒性。
