Alternative Splicing in Heat Shock Protein Transcripts as a Mechanism of Cell Adaptation in Trichophyton rubrum

Abstract

Heat shock proteins (HSPs) are involved in critical processes like host tissue invasion, resistance, and pathogenicity in dermatophytes. RNA-Seq analysis of Trichophyton rubrum exposed to undecanoic acid (UDA) revealed intron retention events in HSP transcripts. Because HSPs are modulated in response to various stimuli and as alternative splicing (AS) can result in a broad diversity in the proteome of eukaryotic cells, our objective was to confirm the aforementioned retention events, investigating their consequences and extent. Furthermore, we aimed to determine: (1) the expression profile of HSP genes in an infection-like scenario and (2) the importance of Hsp90 for the keratinolytic potential of T. rubrum. RT and qPCR analyses comparing the exposure to UDA and terbinafine (TRB) confirmed the presence of two mRNA isoforms of the hsp7-like gene, with distinct expression patterns in response to UDA and TRB. The HSP expression profile revealed two upregulated, three downregulated, and four unmodulated transcripts; Hsp90 inhibition by 17-AAG resulted in a significant decrease in keratinolytic potential at 37 °C. Altogether, these results broaden the current knowledge on the importance of HSP-mediated pathways for cell adaptation and other aspects of dermatophyte biology, indicating that HSP network proteins can be potential targets for antifungal therapy.

Functional surface proteomic profiling reveals the host heat‐shock protein A8 as a mediator of Lichtheimia corymbifera recognition by murine alveolar macrophages

“…Fungal HSPs also have a role in the resistance to antifungal compounds, as shown by Hsp90, which enhances the resistance of Aspergillus and Candida species to azoles and echinocandins (Robbins et al ., 2017). Moreover, Hsp90 is considered as a promising therapeutic target against Trichophyton rubrum (Neves‐da‐Rocha et al ., 2019). Overexpression of Hsp12p in C .…”

Metabolomic analysis of Trichophyton rubrum and Microsporum canis during keratin degradation

“…The keratinolytic potential of T. rubrum and M. canis was performed according to previously described protocols 53 – 55 with modifications. In brief, 1 × 10 7 cells/ml of T. rubrum and M. canis were germinated into YG medium (2% w/v glucose, 0.5% w/v yeast extract) for 72 h. After the incubation time, the cultures were filtered using Falcon 40 µm Cell Strainer (Corning, New York, USA) and then transferred to the 25 ml of keratin medium (2.5 g/l) (PROTEINA, Łódź, Poland) at pH 5.0, the material was incubated for 24, 48, 72 and 96 h at 30 °C under constant agitation (120 rpm).…”

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

“…In yeasts, their regulation is dependent on two regulatory sequences, the stress response elements (STRE) and the heat shock elements (HSE), which are binding sites for the transcription factors Msn24p and Hsf1p, respectively [ 81 , 82 , 83 ]. During interaction with host molecules, some Hsp-encoding genes were upregulated in T. rubrum, such as hsp30 , hsp104 , and hsp75-like, as shown after co-culture with keratinocytes [ 84 ], and the overexpression of hsp60 , hsp70 , and hsp78 genes was promoted through interaction with human nail fragments [ 85 , 86 ]. Moreover, three genes that encode putative Hsp70 proteins were also identified in A. benhamiae after exposure to keratin [ 38 ].…”

“…Inhibition of Hsp90 by the synthetic compound 17-AGG (17-allylamino-17-demethoxygeldanamycin) caused a severe compromise in nail infection by T. rubrum and impaired the keratinolytic activity at 37 °C [ 84 , 85 ]. There is a relationship between PacC and Hsf1 in the production of Hsp transcripts.…”