Os fungos dermatófitos são caracterizados pela capacidade de invadir os tecidos queratinizados, usando queratina como principal fonte de nutrientes. Ao invadirem os tecidos hospedeiros eles causam um tipo de micose chamada de dermatofitose. Dentre os dermatófitos, a espécie Trichophyton rubrum é o causador mais comum de tinea pedis, tinea unguium, tinea cruris e tinea corporis, sendo considerado um fungo antropofílico e cosmopolita. Entretanto, o conhecimento da interação deste patógeno com o hospedeiro é escasso. Devido à importância clínica de T. rubrum, este trabalho analisou a composição de aminoácidos de proteínas queratinas oriundas de Homo sapiens e Bos taurus e a expressão de genes envolvidos na degradação de queratina, metabolismo e controle do ciclo celular. O perfil de expressão dos genes sub3 e sub5 que codificam para queratinases, mad2 e mad2B que codificam proteínas envolvidas no controle da mitose, e os genes idh1 (subunidade regulatória da isocitrato desidrogenase - NAD+), idh2 (subunidade catalítica da isocitrato desidrogenase - NAD+), idhp (isocitrato desidrogenase - NADP+), icl (isocitrato liase) e meicl (metilisocitrato liase), que codificam proteínas envolvidas em vias metabólicas, foi analisado após o cultivo de T. rubrum em meios contendo glicose, glicina, glicose com glicina, ou queratina. A atividade queratinolítica foi avaliada após o cultivo de T. rubrum nesses meios e também em unha humana. Além disto, o efeito do antifúngico terbinafina na atividade queratinolítica e na expressão dos genes sub3 e sub5 foi analisado em meios contendo unha humana ou queratina. Após o cultivo de T. rubrum a atividade das enzimas IDH e IDHP componentes do ciclo de Krebs, ICL do ciclo do glioxilato e MeICL do ciclo do metilcitrato também foram avaliadas. Essas análises revelaram que a variação da fonte nutricional, do pH do meio de cultivo, e a presença/ausência do fator de transcrição PacC, proporcionam às diferentes linhagens de T. rubrum utilizadas neste trabalho (CBS, H6 e pacC-1) uma modulação diferenciada do acúmulo de transcritos dos genes, bem como da atividade queratinolítica e atividade das enzimas IDH, IDHP, ICL e MeICL. Outro fenômeno verificado foi que o antifúngico terbinafina afeta o acúmulo de transcritos dos genes sub3 e sub5, e a atividade queratinolítica de acordo com a fonte nutricional e a linhagem de T. rubrum. Além disso, em condições de estresse por pH alcalino a enzima IDHP é preferencialmente requisitada para manutenção do ciclo de Krebs, sendo que a linhagem mutante pacC-1 requisita em maior proporção as vias anapleróticas do que a linhagem selvagem H6. É importante enfatizar que a enzima ICL de T. rubrum possui atividade enzimática regulada por fosforilação, sendo sua atividade reduzida por esta modificação pós traducional. A identificação deste mecanismo de regulação da ICL por fosforilação e as análises dos transcritos de icl sugerem que em T. rubrum a regulação do fluxo de carbono no ciclo do glioxilato ocorra tanto em nível transcricional como pós-traducional. Os resultados obtidos possibilitaram ainda propor o primeiro modelo para T. rubrum que relaciona vias metabólicas, amparado por dados experimentais obtidos após o cultivo deste dermatófito em queratina. / Dermatophytes are fungi characterized by the ability to invade keratinized tissues using keratin as a major source of nutrients. When they invade host tissues they cause a type of ringworm called dermatophytosis. Among the dermatophytes, the species Trichophyton rubrum is the most common cause of tinea pedis, tinea unguium, tinea cruris, and tinea corporis, being considered an anthropophilic and cosmopolitan fungus. However, the knowledge of the interaction of this pathogen with the host is scarce. Due to the clinical importance of T. rubrum, this study analyzed the amino acid composition of keratin proteins derived from Homo sapiens and Bos taurus, and the expression of genes involved in keratin degradation, metabolism, and cell cycle control. The expression profile of the sub3 and sub5 genes, encoding keratinases, mad2 and mad2B, encoding proteins involved in the control of mitosis, and the genes idh1 (regulatory subunit of NAD+ -isocitrate dehydrogenase), idh2 (catalytic subunit of NAD+ -isocitrate dehydrogenase), idhp (NADP+ - isocitrate dehydrogenase), icl (isocitrate lyase), and meicl (metilisocitrate lyase), which encode proteins involved in metabolic pathways, was analyzed after cultivation of T. rubrum in media containing glucose, glycine, glucose and glycine, or keratin. The keratinolytic activity was evaluated after cultivation of T. rubrum in these media and also in human nail. Furthermore, the effect of the antifungal agent terbinafine in keratinase activity and sub3 and sub5 gene expression was analyzed in media containing human nail or keratin. After culturing T. rubrum the enzyme activity of IDH and IDHP, components of the Krebs cycle, ICL of the glyoxylate cycle, and MeICL of the metilcitrato cycle were also evaluated. These analyses revealed that the variation in the nutritional source, the pH of the medium, and the presence/absence of the transcription factor PacC, provide to the different T. rubrum strains used in this study (CBS, H6 and pacC-1) differential modulation of transcripts accumulation of the genes, as well as keratinolytic activity and enzymatic activities of IDH, IDHP, ICL and MeICL. Another phenomenon observed was that the antifungal terbinafine affects the accumulation of transcripts of the genes sub3, sub5, and the keratinolytic activity according to nutritional source and T. rubrum strain. In addition, in stress conditions by alkaline pH the IDHP enzyme is preferably required for maintenance of the Krebs cycle, and the mutant pacC-1 requests the anaplerotic pathways in greater proportion than the wild type strain H6. It is important to emphasize that T. rubrum ICL enzyme has its enzymatic activity regulated by phosphorylation, being reduced by this post translational modification. The identification of this regulation mechanism by phosphorylation of ICL and icl transcripts analysis suggest that in T. rubrum the carbon flux regulation in the glyoxylate cycle occurs at both transcriptional and post-translational levels. The results also made possible the proposition of the first model for T. rubrum correlating metabolic pathways, supported by experimental data obtained after cultivation of this dermatophyte in keratin.

Dermatophytes are a group of fungi, some of which can cause skin diseases in humans and animals due to their ability to degrade keratinized tissue. Representatives of this group also include strains from the Trichophyton benhamiae complex, known to cause dermatophytosis especially of small rodents and rabbits. In the last decade, one of four populations of this complex has spread epidemically across Europe among guinea pigs and their breeders. To answer the question what stands behind the successful spread of this population, the gene expression and production of volatile organic compounds of epidemic and non-epidemic populations of T. benhamiae was investigated. Gene expression of three strains from each population was studied during growth in liquid medium and on ex vivo mouse skin models prepared according to a newly optimized protocol. RNAseq and RT-qPCR methods were chosen for the gene expression analysis. Based on the literature and the results of RNAseq preliminary analysis, several genes were selected for which specific primers were designed. The spectra of the produced volatile organic compounds of the same strains growing on sheep wool in vials were analyzed by GC-MS. While non-epidemic populations did not differ in gene expression and production of volatile organic compounds, the...

Skin infections by keratinophilic fungi are commonly referred to as dermatophytosis and represent a major health burden worldwide. Although patient numbers are on the rise, data on virulence factors, their function and kinetics are scarce. We employed an ex vivo infection model based on guinea pig skin explants (GPSE) for the zoonotic dermatophyte Trichophyton (T.) benhamiae to investigate kinetics of the virulence factors subtilisin (sub) 3, sub 6, metallocarboxypeptidase A (mcpA) and isocitrate lyase (isol) at gene level for ten days. Fluorescence in situ hybridization (FISH) and quantitative polymerase chain reaction (qPCR) were used to detect and quantify the transcripts, respectively. Kingdom-spanning, species-specific and virulence factor-specific probes were successfully applied to isolated fungal elements showing inhomogeneous fluorescence signals along hyphae. Staining results for inoculated GPSE remained inconsistent despite thorough optimization. qPCR revealed a significant increase of sub 3- and mcpA-transcripts toward the end of culture, sub 6 and isol remained at a low level throughout the entire culture period. Sub 3 is tightly connected to the de novo formation of conidia during culture. Since sub 6 is considered an in vivo disease marker. However, the presented findings urgently call for further research on the role of certain virulence factors during infection and disease.

The genus Arthroderma contains predominantly geophilic dermatophytes (naturally occuring in soil). Some species, especially those from Trichophyton terrestre complex, cause human and animal dermatomycosis. In the past, the species boundaries were determined mainly on the basis of biological species concept using in vitro mating experiments. But these nearly 70-years-old findings have not been tested by means of modern taxonomic methods. In total 194 species of the genus Arthroderma (including all available ex-type strains) originating predominantly in USA, Canada and Europe were studied in this thesis. They were mostly isolated from soil (n = 77), animals (n = 50), human clinical material (n = 41) and cave sediment (n = 9). The main goal of the thesis was to elucidate the species boundaries between species A. insingulare, A. lenticulare and A. quadrifidum, that were classified into the T. terrestre complex because of their seemingly identical asexual stage. Further, this work aimed to resolve the relationship between Arthroderma species using the multigene phylogeny and clarify which species are clinically relevant. A multigene phylogeny of the genus Arthroderma was based on the sequences of the ITS rDNA region, β-tubulin (TUB2) and translation elongation factor 1α (TEF1α) genes. The genus...