Expression of genes containing tandem repeat patterns involved in the fungal‐host interaction and in the response to antifungals inTrichophyton rubrum

Abstract

Background: Trichophyton rubrum is the most common aetiological agent of human dermatophytoses. These infections mainly occur in keratinised layers such as skin, hair and nails because the fungus uses keratin as a nutrient source. Fluconazole and amphotericin are antifungal agents most commonly used to treat dermatophytoses and acts on cell membrane ergosterol. Despite the clinical importance of T rubrum, the mechanisms underlying the fungal-host relationship have not yet been clarified. Tandem repeats (TRs) are short DNA sequences that are involved in a variety of adaptive functions, including the process of fungal infection. It is known that the larger the number of TRs in the genome, the greater the capacity of cell-cell junction and surface adhesion, especially when these repeats are present in regions encoding cell surface proteins. Objectives: To identify in silico T rubrum genes containing TR patterns and to analyse the modulation of these genes in culture medium containing keratin (a model simulating skin infection) and antifungal drugs. Methods: The Dermatophyte Tandem Repeats Database (DTRDB) and the FaaPred tool were used to identify four T rubrum genes containing TR patterns. Quantitative real-time (RT) PCR was used to evaluate the gene expression during the growth of T rubrum on keratin and in the presence of fluconazole, amphotericin B and Congo red (acts in the cell wall).Results: The expression of these genes was found to be induced in culture medium containing keratin. In addition, these genes were induced in the presence of antifungal agents, especially fluconazole, indicating an adaptive response to the stress caused by this drug. Conclusion:The results suggest an important role of genes containing TRs in the fungal-host interaction and in the susceptibility to inhibitory compounds, indicating these sequences as new potential targets for the development of antifungal agents. K E Y W O R D S adhesin, cell wall proteins, fluconazole, fungal infection, gene expression | 611 de ABReU et Al.

Epidemiology and Diagnostic Perspectives of Dermatophytoses

“…A vast range of molecular approaches exist in clinical mycology. These approaches are not only limited to diagnostic tests but can also be used for prospecting new antifungal compounds for the treatment of these diseases, as done by [97][98][99], as well as for the identification of conserved regions that contribute to the virulence of these pathogens as described by [100], enabling the discovery of new therapeutic targets. Moreover, technologies for large-scale transcriptome analyses such as RNAseq and microarray have contributed to a better understanding of dermatophyte-host interactions at the molecular level [101,102], in addition to providing new insight into the effect of commercial antifungals such as terbinafine on species such as T. rubrum.…”

State-of-the-Art Dermatophyte Infections: Epidemiology Aspects, Pathophysiology, and Resistance Mechanisms

“…Tandem repeats containing proteins are potential candidates for cell-to-cell junctions, surface adhesion, and fungal virulence [ 49 ]. Recently, genes that encode cell wall proteins with tandem repeats have been investigated, revealing the upregulation of mad1 adhesin (TERG_08771), msb2 (TERG_05644), scw11 (TERG_05576), and mps1 (TERG_08369) during T. rubrum growth on keratin substrates [ 50 ]. In silico characterization of the protein codified by TERG_08771 (Mad 1 adhesin), demonstrated the presence of domains potentially involved in adhesion, such as collagen triple helix repeat, mucin-like glycoprotein, and flocculin type 3 repeat [ 51 ].…”