Martins-Santana Leonardo, Petrucelli Monise Fazolin, Sanches Pablo R, Martinez-Rossi Nilce M, Rossi Antonio
Laboratory of Genetics and Molecular Biology of Fungi, Department of Genetics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil.
Front Microbiol. 2022 Jun 17;13:930398. doi: 10.3389/fmicb.2022.930398. eCollection 2022.
is the most common causative agent of dermatophytosis worldwide and uses keratinized substrates such as skin and nails as its main source of nutrition during infection. Its pathogenic character relies on colonization and viability maintenance at the target host sites. Since fungal physiology must adapt and respond to host conditions for the successful establishment of infection, biological mechanisms are constantly being triggered by to guarantee its survival in the host environment. The ability of this fungus to sense and modulate the secretion of specific proteases according to environmental pH signaling is considered as a pivotal virulence factor for effective invasion and persistence of infection in the host. Transcriptional regulation of genes encoding specific proteases, such as peptidases, is a key biological process that drives physiological modulation to meet fungal requirements. It accomplishes a robust balance among transcript isoforms that can be directed to perform distinct cellular functions. Thus, alternative splicing mechanisms are suitable for fungal cells to establish a balance toward reprogramming protein translation to impair or boost physiological conditions. In this study, we investigated the role of alternative splicing, especially intron retention events, in generating isoforms of virulence factors in mediated by transcriptional coordination of the protein StuA, a recently described transcription factor in this fungus. By analyzing the previous gene expression data provided by RNA-sequencing and after validation by reverse transcriptase quantitative polymerase chain reaction (RT-qPCR), we observed that two peptidase-coding genes (TERG_00734 and TERG_04614) could be direct targets of alternative splicing in the presence of keratin. Furthermore, protease isoforms generated by alternative splicing in were also detected in a co-culture with human keratinocytes, highlighting the role of these proteins in keratin deconstruction. Our results strongly suggest the influence of StuA on the regulation of virulence factors in and dermatophyte infections by triggering the transcription of the peptidase genes mentioned above in an alternative splicing-independent balance. The results elucidate how fungal cells drive alternate splicing to promote physiological adaptations and show that transcriptional regulation and virulence traits are robust elements required for dermatophyte infection.
是全球皮肤癣菌病最常见的病原体，在感染期间利用皮肤和指甲等角质化底物作为其主要营养来源。其致病特性依赖于在靶宿主部位的定植和活力维持。由于真菌生理学必须适应并响应宿主条件以成功建立感染，因此生物机制不断被触发以确保其在宿主环境中的存活。这种真菌根据环境pH信号感知并调节特定蛋白酶分泌的能力被认为是在宿主体内有效侵袭和持续感染的关键毒力因子。编码特定蛋白酶（如肽酶）的基因的转录调控是驱动生理调节以满足真菌需求的关键生物学过程。它在可被导向执行不同细胞功能的转录异构体之间实现了强大的平衡。因此，可变剪接机制适合真菌细胞建立平衡，以重新编程蛋白质翻译来损害或促进生理条件。在本研究中，我们研究了可变剪接，特别是内含子保留事件，在由该真菌最近描述的转录因子StuA的转录协调介导的毒力因子异构体产生中的作用。通过分析RNA测序提供的先前基因表达数据并经逆转录定量聚合酶链反应（RT-qPCR）验证后，我们观察到两个肽酶编码基因（TERG_00734和TERG_04614）在有角蛋白存在的情况下可能是可变剪接的直接靶点。此外，在与人角质形成细胞的共培养中也检测到了由可变剪接在中产生的蛋白酶异构体，突出了这些蛋白质在角蛋白解构中的作用。我们的结果强烈表明StuA通过在不依赖可变剪接的平衡中触发上述肽酶基因的转录，对中以及皮肤癣菌感染的毒力因子调节产生影响。结果阐明了真菌细胞如何驱动可变剪接以促进生理适应，并表明转录调控和毒力特性是皮肤癣菌感染所需的重要因素。
