Andrade Rosângela V, Paes Hugo C, Nicola André M, de Carvalho Maria José A, Fachin Ana Lúcia, Cardoso Renato S, Silva Simoneide S, Fernandes Larissa, Silva Silvana P, Donadi Eduardo A, Sakamoto-Hojo Elza T, Passos Geraldo A S, Soares Célia M A, Brígido Marcelo M, Felipe Maria Sueli S
Depto. de Biologia Celular, Universidade de Brasília, 70910-900, Brasília-DF, Brazil.
BMC Genomics. 2006 Aug 14;7:208. doi: 10.1186/1471-2164-7-208.
Mycelium-to-yeast transition in the human host is essential for pathogenicity by the fungus Paracoccidioides brasiliensis and both cell types are therefore critical to the establishment of paracoccidioidomycosis (PCM), a systemic mycosis endemic to Latin America. The infected population is of about 10 million individuals, 2% of whom will eventually develop the disease. Previously, transcriptome analysis of mycelium and yeast cells resulted in the assembly of 6,022 sequence groups. Gene expression analysis, using both in silico EST subtraction and cDNA microarray, revealed genes that were differential to yeast or mycelium, and we discussed those involved in sugar metabolism. To advance our understanding of molecular mechanisms of dimorphic transition, we performed an extended analysis of gene expression profiles using the methods mentioned above.
In this work, continuous data mining revealed 66 new differentially expressed sequences that were MIPS(Munich Information Center for Protein Sequences)-categorised according to the cellular process in which they are presumably involved. Two well represented classes were chosen for further analysis: (i) control of cell organisation - cell wall, membrane and cytoskeleton, whose representatives were hex (encoding for a hexagonal peroxisome protein), bgl (encoding for a 1,3-beta-glucosidase) in mycelium cells; and ags (an alpha-1,3-glucan synthase), cda (a chitin deacetylase) and vrp (a verprolin) in yeast cells; (ii) ion metabolism and transport - two genes putatively implicated in ion transport were confirmed to be highly expressed in mycelium cells - isc and ktp, respectively an iron-sulphur cluster-like protein and a cation transporter; and a putative P-type cation pump (pct) in yeast. Also, several enzymes from the cysteine de novo biosynthesis pathway were shown to be up regulated in the yeast form, including ATP sulphurylase, APS kinase and also PAPS reductase.
Taken together, these data show that several genes involved in cell organisation and ion metabolism/transport are expressed differentially along dimorphic transition. Hyper expression in yeast of the enzymes of sulphur metabolism reinforced that this metabolic pathway could be important for this process. Understanding these changes by functional analysis of such genes may lead to a better understanding of the infective process, thus providing new targets and strategies to control PCM.
巴西副球孢子菌在人类宿主体内从菌丝体向酵母型的转变对其致病性至关重要，因此这两种细胞类型对于副球孢子菌病（PCM）的发生发展都至关重要，PCM是一种拉丁美洲特有的系统性真菌病。受感染人群约有1000万，其中2%最终会发病。此前，对菌丝体和酵母细胞进行转录组分析，共组装出6022个序列组。利用电子EST消减和cDNA微阵列进行基因表达分析，揭示了酵母型或菌丝体型差异表达的基因，我们还讨论了参与糖代谢的基因。为了进一步了解双态转变的分子机制，我们使用上述方法对基因表达谱进行了扩展分析。
在这项研究中，持续的数据挖掘发现了66个新的差异表达序列，根据它们可能参与的细胞过程，按照慕尼黑蛋白质序列信息中心（MIPS）进行分类。选择了两个代表性较好的类别进行进一步分析：（i）细胞组织调控——细胞壁、细胞膜和细胞骨架，其代表基因在菌丝体细胞中有hex（编码一种六边形过氧化物酶体蛋白）、bgl（编码一种1,3-β-葡糖苷酶）；在酵母细胞中有ags（一种α-1,3-葡聚糖合酶）、cda（一种几丁质脱乙酰酶）和vrp（一种维氏肌动蛋白结合蛋白）；（ii）离子代谢和转运——两个推测与离子转运有关的基因被证实在菌丝体细胞中高表达——isc和ktp，分别是一种铁硫簇样蛋白和一种阳离子转运蛋白；在酵母中有一个推测的P型阳离子泵（pct）。此外，半胱氨酸从头生物合成途径中的几种酶在酵母型中上调，包括ATP硫酸化酶、APS激酶以及PAPS还原酶。
综上所述，这些数据表明，在双态转变过程中，一些参与细胞组织和离子代谢/转运的基因表达存在差异。酵母中硫代谢酶的高表达强化了该代谢途径可能对这一过程很重要。通过对这些基因进行功能分析来了解这些变化，可能有助于更好地理解感染过程，从而为控制PCM提供新的靶点和策略。
