{"database":"biostudies-literature","file_versions":[],"scores":null,"additional":{"submitter":["Kalem MC"],"funding":["NIAID NIH HHS","HHS | NIH | National Institute of Allergy and Infectious Diseases"],"pagination":["e03225-20"],"full_dataset_link":["https://www.ebi.ac.uk/biostudies/studies/S-EPMC7844544"],"repository":["biostudies-literature"],"omics_type":["Unknown"],"volume":["12(1)"],"pubmed_abstract":["The human fungal pathogen <i>Cryptococcus neoformans</i> is intrinsically resistant to the echinocandin antifungal drug caspofungin, which targets the β-1,3-glucan synthase encoded by <i>FKS1</i> Echinocandins have been on the market for 20 years, yet they are the newest class of antifungal drugs. Analysis of a <i>C. neoformans</i><i>puf4</i>Δ mutant, lacking the pumilio/FBF RNA binding protein family member Puf4, revealed exacerbated caspofungin resistance. In contrast, overexpression of <i>PUF4</i> resulted in caspofungin sensitivity. The <i>FKS1</i> mRNA contains three Puf4-binding elements (PBEs) in its 5' untranslated region. Puf4 binds with specificity to this region of <i>FKS1</i> The <i>FKS1</i> mRNA was destabilized in the <i>puf4</i>Δ mutant, and the abundance of the <i>FKS1</i> mRNA was reduced compared to wild type, suggesting that Puf4 is a positive regulator of <i>FKS1</i> mRNA stability. In addition to <i>FKS1</i>, the abundance of additional cell wall biosynthesis genes, including chitin synthases (<i>CHS3</i>, <i>CHS4</i>, and <i>CHS6</i>) and deacetylases (<i>CDA1</i>, <i>CDA2</i>, and <i>CDA3</i>) as well as a β-1,6-glucan synthase gene (<i>SKN1</i>), was regulated by Puf4. The use of fluorescent dyes to quantify cell wall components revealed that the <i>puf4</i>Δ mutant had increased chitin content, suggesting a cell wall composition that is less reliant on β-1,3-glucan. Overall, our findings suggest a mechanism by which caspofungin resistance, and more broadly, cell wall biogenesis, is regulated post-transcriptionally by Puf4.<b>IMPORTANCE</b><i>Cryptococcus neoformans</i> is an environmental fungus that causes pulmonary and central nervous system infections. It is also responsible for 15% of AIDS-related deaths. A significant contributor to the high morbidity and mortality statistics is the lack of safe and effective antifungal therapies, especially in resource-poor settings. Yet, antifungal drug development has stalled in the pharmaceutical industry. Therefore, it is essential to understand the mechanism by which <i>C. neoformans</i> is resistant to caspofungin to design adjunctive therapies to potentiate the drug's activity toward this important pathogen."],"journal":["mBio"],"pubmed_title":["Puf4 Mediates Post-transcriptional Regulation of Cell Wall Biosynthesis and Caspofungin Resistance in Cryptococcus neoformans."],"pmcid":["PMC7844544"],"funding_grant_id":["R21 AI133133","R01 AI131977"],"pubmed_authors":["Glazier VE","Panepinto JC","Kalem MC","Subbiah H","Leipheimer J"],"additional_accession":[]},"is_claimable":false,"name":"Puf4 Mediates Post-transcriptional Regulation of Cell Wall Biosynthesis and Caspofungin Resistance in Cryptococcus neoformans.","description":"The human fungal pathogen <i>Cryptococcus neoformans</i> is intrinsically resistant to the echinocandin antifungal drug caspofungin, which targets the β-1,3-glucan synthase encoded by <i>FKS1</i> Echinocandins have been on the market for 20 years, yet they are the newest class of antifungal drugs. Analysis of a <i>C. neoformans</i><i>puf4</i>Δ mutant, lacking the pumilio/FBF RNA binding protein family member Puf4, revealed exacerbated caspofungin resistance. In contrast, overexpression of <i>PUF4</i> resulted in caspofungin sensitivity. The <i>FKS1</i> mRNA contains three Puf4-binding elements (PBEs) in its 5' untranslated region. Puf4 binds with specificity to this region of <i>FKS1</i> The <i>FKS1</i> mRNA was destabilized in the <i>puf4</i>Δ mutant, and the abundance of the <i>FKS1</i> mRNA was reduced compared to wild type, suggesting that Puf4 is a positive regulator of <i>FKS1</i> mRNA stability. In addition to <i>FKS1</i>, the abundance of additional cell wall biosynthesis genes, including chitin synthases (<i>CHS3</i>, <i>CHS4</i>, and <i>CHS6</i>) and deacetylases (<i>CDA1</i>, <i>CDA2</i>, and <i>CDA3</i>) as well as a β-1,6-glucan synthase gene (<i>SKN1</i>), was regulated by Puf4. The use of fluorescent dyes to quantify cell wall components revealed that the <i>puf4</i>Δ mutant had increased chitin content, suggesting a cell wall composition that is less reliant on β-1,3-glucan. Overall, our findings suggest a mechanism by which caspofungin resistance, and more broadly, cell wall biogenesis, is regulated post-transcriptionally by Puf4.<b>IMPORTANCE</b><i>Cryptococcus neoformans</i> is an environmental fungus that causes pulmonary and central nervous system infections. It is also responsible for 15% of AIDS-related deaths. A significant contributor to the high morbidity and mortality statistics is the lack of safe and effective antifungal therapies, especially in resource-poor settings. Yet, antifungal drug development has stalled in the pharmaceutical industry. Therefore, it is essential to understand the mechanism by which <i>C. neoformans</i> is resistant to caspofungin to design adjunctive therapies to potentiate the drug's activity toward this important pathogen.","dates":{"release":"2021-01-01T00:00:00Z","publication":"2021 Jan","modification":"2026-06-14T03:22:21.887Z","creation":"2026-06-14T03:09:24.6Z"},"accession":"S-EPMC7844544","cross_references":{"pubmed":["33436441"],"doi":["10.1128/mBio.03225-20"]}}