Molecular remodelling of Cryptococcus neoformans during adaptation to host temperature

Introduction. The ability of Cryptococcus neoformans to adapt to host temperature is an important feature of its pathogenic potential and requires extensive cellular remodelling. Hypothesis/Gap Statement. Although C. neoformans undergoes substantial molecular changes at host temperature, the extent to which transcriptomic and proteomic responses are concordant during this adaptation remains incompletely understood. Aim. We investigated the molecular and metabolic responses of the C. neoformans H99 strain grown at 30 and 37 °C using an integrated transcriptomic, proteomic and functional approach. Methodology. RNA sequencing and quantitative proteomics were performed after 24 h of growth at 30 and 37 °C. Differentially expressed transcripts and proteins were identified, and matched transcript–protein features were analysed for directional concordance and quantitative correlation. Cellular metabolic activity was assessed using the 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) reduction assay. Results. RNA-seq analysis identified 344 upregulated and 428 downregulated transcripts at 37 °C. Upregulated transcripts were enriched in functions related to ribosome biogenesis, translation, protein folding and mitochondrial-associated processes, whereas downregulated transcripts were associated with carbohydrate metabolism and other metabolic functions. Proteomic analysis revealed a more selective response, with increased abundance of proteins associated with oxidoreductase activity, sterol and isoprenoid biosynthesis, glutamine metabolism and metal-binding functions. Integration of the transcriptomic and proteomic datasets identified 305 matched features, of which 162 (53.1%) showed directional concordance. However, no significant quantitative correlation was observed between transcript and protein fold changes (Spearman ρ = −0.005, P =0.934; Pearson r=0.003, P =0.959). Cells grown at 37 °C also showed significantly increased XTT reduction, indicating higher cellular metabolic activity under the conditions tested. Conclusion. Adaptation to host temperature involves broad transcriptional remodelling accompanied by selective proteomic changes and increased cellular metabolic activity. These findings provide a molecular framework for further investigating the mechanisms underlying thermoadaptation and their contribution to the pathogenic potential of C. neoformans .