Cross talk between the cell wall integrity and cyclic AMP/protein kinase A pathways in Cryptococcus neoformans.
Cross talk between the cell wall integrity and cyclic AMP/protein kinase A pathways in Cryptococcus neoformans.
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DOI：
10.1128/mbio.01573-14
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发表时间：
2014-08-12
期刊：
影响因子：
6.4
通讯作者：
Lodge JK
中科院分区：
文献类型：
--
作者：
Donlin MJ;Upadhya R;Gerik KJ;Lam W;VanArendonk LG;Specht CA;Sharma NK;Lodge JK
新型隐球菌是一种真菌病原体，免疫功能低下的人，导致致命的脑膜炎。真菌细胞壁对于新生隐球菌的存活和致病是必不可少的，并且细胞壁的生物合成和修复主要由细胞壁完整性（CWI）信号通路控制。先前的工作已经表明，在小鼠模型中，编码CWI信号通路中的四种主要激酶（即PKC 1、BCK 1、MKK 2和MPK 1）的基因的缺失导致严重的细胞壁表型、对各种细胞壁应激物的敏感性以及Mpk 1的毒力降低。在这里，我们研究了与野生型细胞相比，BCK 1，MKK 2和MPK 1基因缺失的整体转录反应。我们发现超过1,000个基因在一个或多个缺失菌株中差异表达，其中115个基因在所有三个菌株中差异表达，其中许多基因已被鉴定为受环腺苷酸（cAMP）/蛋白激酶A（PKA）途径调控的基因。激酶缺失菌株中cAMP水平的生化测量显示，与野生型菌株相比，所有缺失菌株中的cAMP显著减少。缺失菌株也产生了显着较小的胶囊比野生型KN 99菌株在胶囊诱导条件下，虽然他们脱落的胶囊水平是类似的野生型脱落。最后，添加外源性cAMP导致对细胞壁应力的敏感性降低，并将表面囊恢复到接近野生型的水平。因此，我们有直接的证据表明，CWI和cAMP/PKA途径之间的串扰，可能有重要的影响，调节细胞壁和胶囊的稳态。新型隐球菌是一种真菌病原体，免疫功能低下的人，导致致命的脑膜炎。真菌细胞壁对于新生隐球菌的存活和致病是必不可少的，并且细胞壁的生物合成和修复主要由细胞壁完整性（CWI）信号通路控制。在这项研究中，我们证明了CWI通路中三种核心激酶中任何一种的缺失不仅影响细胞壁，而且影响表面囊的数量。任何激酶的缺失导致细胞环AMP（cAMP）水平显著降低，并且外源性cAMP的添加挽救了包膜缺陷和一些细胞壁缺陷，支持CWI途径在结合cAMP/蛋白激酶A途径调节包膜中的直接作用。
Cryptococcus neoformans is a fungal pathogen of immunocompromised people that causes fatal meningitis. The fungal cell wall is essential to viability and pathogenesis of C. neoformans, and biosynthesis and repair of the wall is primarily controlled by the cell wall integrity (CWI) signaling pathway. Previous work has shown that deletion of genes encoding the four major kinases in the CWI signaling pathway, namely, PKC1, BCK1, MKK2, and MPK1 results in severe cell wall phenotypes, sensitivity to a variety of cell wall stressors, and for Mpk1, reduced virulence in a mouse model. Here, we examined the global transcriptional responses to gene deletions of BCK1, MKK2, and MPK1 compared to wild-type cells. We found that over 1,000 genes were differentially expressed in one or more of the deletion strains, with 115 genes differentially expressed in all three strains, many of which have been identified as genes regulated by the cyclic AMP (cAMP)/protein kinase A (PKA) pathway. Biochemical measurements of cAMP levels in the kinase deletion strains revealed significantly less cAMP in all of the deletion strains compared to the wild-type strain. The deletion strains also produced significantly smaller capsules than the wild-type KN99 strain did under capsule-inducing conditions, although the levels of capsule they shed were similar to those shed by the wild type. Finally, addition of exogenous cAMP led to reduced sensitivity to cell wall stress and restored surface capsule to levels near those of wild type. Thus, we have direct evidence of cross talk between the CWI and cAMP/PKA pathways that may have important implications for regulation of cell wall and capsule homeostasis. Cryptococcus neoformans is a fungal pathogen of immunocompromised people that causes fatal meningitis. The fungal cell wall is essential to viability and pathogenesis of C. neoformans, and biosynthesis and repair of the wall are primarily controlled by the cell wall integrity (CWI) signaling pathway. In this study, we demonstrate that deletion of any of three core kinases in the CWI pathway impacts not only the cell wall but also the amount of surface capsule. Deletion of any of the kinases results in significantly reduced cellular cyclic AMP (cAMP) levels, and addition of exogenous cAMP rescues the capsule defect and some cell wall defects, supporting a direct role for the CWI pathway in regulation of capsule in conjunction with the cAMP/protein kinase A pathway.