Sexual development in Cryptococcus neoformans

描述（由申请人提供）：本提案的目标是确定机会性人类真菌病原体新隐球菌控制性发育的分子机制。性发育导致孢子的产生，孢子可以分散到环境中。据认为，新生梭状芽孢杆菌是通过将真菌孢子吸入肺泡的呼吸途径从环境源感染人类的。一旦被吸入，新生梭状菌可以传播到中枢神经系统，引起致命的脑膜炎。了解隐球菌性发育和孢子产生的生物学过程有望为预防和/或治疗隐球菌疾病提供有用的信息。这项研究也引起了普遍的兴趣，因为机会真菌是新兴的病原体：了解基本的真菌生物学为开发更有效的预防和治疗真菌疾病的方法奠定了基础。在C. neoformmans中，性发育是由性诱导基因SXI1a和SXI2a控制的，但它们的作用机制尚不清楚。本实验旨在阐明SXI1a和SXI2a调控基因表达驱动性别分化的机制。利用遗传、生化、生物信息学和细胞生物学的方法，我们将1)通过鉴定和表征Sxi1a和Sxi2a的下游靶点，绘制由Sxi1a和Sxi2a控制的调控回路；2)通过评估它们的结构和功能之间的关系，建立控制性发育所需的Sxi1a和Sxi2a蛋白的特性；3)研究性发育所需的细胞过程，特别关注双核丝状结构。本文提出的各种方法将阐明性发育的早期阶段，并为新生C.虫体内感染性颗粒的产生提供新的见解。

DESCRIPTION (provided by the applicant): The goal of this proposal is to determine the molecular mechanisms by which sexual development is controlled in the opportunistic human fungal pathogen Cryptococcus neoformans. Sexual development results in the production of spores that can be dispersed into the environment. C. neoformans is thought to infect humans from environmental sources via a respiratory route in which fungal spores are inhaled into the alveoli of the lungs. Once inhaled, C. neoformans can disseminate to the central nervous system and cause a fatal form of meningitis. Understanding the biology of sexual development and spore production in C. neoformans promises to provide information useful in the prevention and/or treatment of cryptococcal disease. This study is also of general interest because opportunistic fungi are emerging pathogens: understanding basic fungal biology sets the stage for the development of more effective methods of preventing and treating fungal disease in general. In C. neoformans sexual development is controlled by the Sex Inducer genes, SXI1a and SXI2a, but the mechanism by which they act is unknown. The experiments outlined in this proposal are designed to elucidate the mechanism by which SXI1a and SXI2a regulate gene expression to drive sexual differentiation. Using genetic, biochemical, bioinformatic, and cell biological approaches we will 1) map the regulatory circuit controlled by Sxi1a and Sxi2a by identifying and characterizing their downstream targets, 2) establish the properties of the Sxi1a and Sxi2a proteins required to control sexual development by evaluating the relationships between their structures and functions, and 3) investigate the cellular processes required for sexual development with a specific focus on dikaryotic filamentation. The diverse approaches presented here will elucidate the early stages of sexual development and lend new insights into how infectious particle production occurs in C. neoformans.