Previous reports have demonstrated that the peptide derived from LfcinB, R-1-R, exhibits anti-Candida activity, which is enhanced when combined with an extract from the Bidens pilosa plant. However, the mechanism of action remains unexplored. In this research, a proteomic study was carried out, followed by a bioinformatic analysis and biological assays in both the SC5314 strain and a fluconazole-resistant isolate of Candida albicans after incubation with R-1-R. The proteomic data revealed that treatment with R-1-R led to the up-regulation of most differentially expressed proteins compared to the controls in both strains. These proteins are primarily involved in membrane and cell wall biosynthesis, membrane transport, oxidative stress response, the mitochondrial respiratory chain, and DNA damage response. Additionally, proteomic analysis of the C. albicans parental strain SC5314 treated with R-1-R combined with an ethanolic extract of B. pilosa was performed. The differentially expressed proteins following this combined treatment were involved in similar functional processes as those treated with the R-1-R peptide alone but were mostly down-regulated (data are available through ProteomeXchange with identifier PXD053558). Biological assays validated the proteomic results, evidencing cell surface damage, reactive oxygen species generation, and decreased mitochondrial membrane potential. These findings provide insights into the complex antifungal mechanisms of the R-1-R peptide and its combination with the B. pilosa extract, potentially informing future studies on natural product derivatives.

Primary liver cancer usually occurs in the context of chronic liver disease (CLD), in association with fibrosis. Platelets have emerged as important regulators of CLD and liver cancer, although their precise function and mechanism of action need to be clarified. C3G (RapGEF1) regulates platelet activation, adhesion, and secretion. Here we evaluate the role of platelet C3G in chemically induced fibrosis and liver cancer associated with fibrosis using genetically modified mouse models. We found that while overexpression of full‐length C3G in platelets decreased liver fibrosis induced by chronic treatment with CCl₄, overexpressed C3G lacking the catalytic domain did not, although in both cases platelet recruitment to the liver was similar. In addition, C3G deletion in platelets (PF4‐C3GKO mouse model) increased CCl₄‐induced liver damage and hepatic fibrosis, reducing liver platelets and macrophages. Moreover, early liver immune response to CCl₄ was altered in PF4‐C3GKO mice, with a remarkable lower activation of macrophages and increased monocyte‐derived macrophages compared to WT mice. On the other hand, in response to DEN+CCl₄, PF4‐C3G WT mice exhibited more and larger liver tumors than PF4‐C3GKO mice, accompanied by the presence of more platelets, despite having less fibrosis in previous steps. Liver immune cell populations were also differentially regulated in PF4‐C3GKO mice, highlighting the higher number of macrophages, likely with a pro‐inflammatory phenotype, present in the liver in response to chronic DEN+CCl₄ treatment. Proteins upregulated or downregulated in platelet‐rich plasma from PF4‐C3GKO compared to WT mice might regulate the immune response and tumor development. In this regard, enrichment analyses using proteomic data showed changes in several proteins involved in platelet activation and immune response pathways. Additionally, the higher secretion of CD40L by PF4‐C3GKO platelets could contribute to their antitumor effect. Therefore, platelet C3G presents antifibrotic and protumor effects in the liver, likely mediated by changes in the immune response. © 2025 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

It was previously reported that the peptide derived from LfcinB, R-1-R exhibited anti-Candida activity and this activity was enhanced in combination with an extract from the Bidens pilosa plant. However, the mechanism of action has not been studied. In the current study, a proteomic study was carried out, followed by a bioinformatic analysis and biological assays in both SC5314 strain and a fluconazole-resistant isolate of Candida albicans, after incubation with R-1-R. The proteomic data showed that after treatment with R-1-R in the two study strains, most of the differentially expressed proteins in comparison to controls were up-regulated. These proteins were mainly involved in membrane and cell wall biosynthesis, membrane transporters, oxidative stress, the mitochondrial respiratory chain, and response to DNA damage. Besides, the proteomic analysis of C. albicans parental strain SC5314 treated with R-1-R in combination with an ethanolic extract of B. pilosa was also undertaken. The proteins differentially expressed after this treatment were involved in similar functional processes as the proteins differentially expressed after treatment with R-1-R peptide alone, but at different levels and were mostly down-regulated. The biological assays allowed validation of the proteomic results, evidencing damage to the cell surface, generation of reactive oxygen species and decrease in mitochondrial membrane potential. The results provide information to begin to unlock the understanding of the complex antifungal mode of action of the R-1-R peptide, its combination with the extract, and possibly other derivatives of natural products.

We describe a new release of the Candida albicans PeptideAtlas proteomics spectral resource (build 2024-03), providing a sequence coverage of 79.5% at the canonical protein level, matched mass spectrometry spectra, and experimental evidence identifying 3382 and 536 phosphorylated serine and threonine sites with false localization rates of 1% and 5.3%, respectively. We provide a tutorial on how to use the PeptideAtlas and associated tools to access this information. The C. albicans PeptideAtlas summary web page provides "Build overview", "PTM coverage", "Experiment contribution", and "Data set contribution" information. The protein and peptide information can also be accessed via the Candida Genome Database via hyperlinks on each protein page. This allows users to peruse identified peptides, protein coverage, post-translational modifications (PTMs), and experiments that identify each protein. Given the value of understanding the PTM landscape in the sequence of each protein, a more detailed explanation of how to interpret and analyze PTM results is provided in the PeptideAtlas of this important pathogen. Candida albicans PeptideAtlas web page: https://db.systemsbiology.net/sbeams/cgi/PeptideAtlas/buildDetails?atlas_build_id=578.