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Sethi SC, Bharati M, Kumar Y, Yadav U, Saini H, Alam P, Komath SS. The ER-Resident Ras Inhibitor 1 (Eri1) of Candida albicans Inhibits Hyphal Morphogenesis via the Ras-Independent cAMP-PKA Pathway. ACS Infect Dis 2024; 10:3528-3543. [PMID: 39119676 DOI: 10.1021/acsinfecdis.4c00175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2024]
Abstract
Ras signaling and glycosylphosphatidylinositol (GPI) biosynthesis are mutually inhibitory in S. cerevisiae (Sc). The inhibition is mediated via an interaction of yeast Ras2 with the Eri1 subunit of its GPI-N-acetylglucosaminyl transferase (GPI-GnT), the enzyme catalyzing the very first GPI biosynthetic step. In contrast, Ras signaling and GPI biosynthesis in C. albicans (Ca) are mutually activated and together control the virulence traits of the human fungal pathogen. What might be the role of Eri1 in this pathogen? The present manuscript addresses this question while simultaneously characterizing the cellular role of CaEri1. It is either nonessential or required at very low levels for cell viability in C. albicans. Severe depletion of CaEri1 results in reduced GPI biosynthesis and cell wall defects. It also produces hyperfilamentation phenotypes in Spider medium as well as in bicarbonate medium containing 5% CO2, suggesting that both the Ras-dependent and Ras-independent cAMP-PKA pathways for hyphal morphogenesis are activated in these cells. Pull-down and acceptor-photobleaching FRET experiments suggest that CaEri1 does not directly interact with CaRas1 but does so through CaGpi2, another GPI-GnT subunit. We showed previously that CaGpi2 is downstream of CaEri1 in cross talk with CaRas1 and for Ras-dependent hyphal morphogenesis. Here we show that CaEri1 is downstream of all GPI-GnT subunits in inhibiting Ras-independent filamentation. CaERI1 also participates in intersubunit transcriptional cross talk within the GPI-GnT, a feature unique to C. albicans. Virulence studies using G. mellonella larvae show that a heterozygous strain of CaERI1 is better cleared by the host and is attenuated in virulence.
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Affiliation(s)
| | - Monika Bharati
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Yatin Kumar
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Usha Yadav
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Harshita Saini
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Parvez Alam
- School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Sneha Sudha Komath
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
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Komath SS. To each its own: Mechanisms of cross-talk between GPI biosynthesis and cAMP-PKA signaling in Candida albicans versus Saccharomyces cerevisiae. J Biol Chem 2024; 300:107444. [PMID: 38838772 PMCID: PMC11294708 DOI: 10.1016/j.jbc.2024.107444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 05/24/2024] [Accepted: 05/29/2024] [Indexed: 06/07/2024] Open
Abstract
Candida albicans is an opportunistic fungal pathogen that can switch between yeast and hyphal morphologies depending on the environmental cues it receives. The switch to hyphal form is crucial for the establishment of invasive infections. The hyphal form is also characterized by the cell surface expression of hyphae-specific proteins, many of which are GPI-anchored and important determinants of its virulence. The coordination between hyphal morphogenesis and the expression of GPI-anchored proteins is made possible by an interesting cross-talk between GPI biosynthesis and the cAMP-PKA signaling cascade in the fungus; a parallel interaction is not found in its human host. On the other hand, in the nonpathogenic yeast, Saccharomyces cerevisiae, GPI biosynthesis is shut down when filamentation is activated and vice versa. This too is achieved by a cross-talk between GPI biosynthesis and cAMP-PKA signaling. How are diametrically opposite effects obtained from the cross-talk between two reasonably well-conserved pathways present ubiquitously across eukarya? This Review attempts to provide a model to explain these differences. In order to do so, it first provides an overview of the two pathways for the interested reader, highlighting the similarities and differences that are observed in C. albicans versus the well-studied S. cerevisiae model, before going on to explain how the different mechanisms of regulation are effected. While commonalities enable the development of generalized theories, it is hoped that a more nuanced approach, that takes into consideration species-specific differences, will enable organism-specific understanding of these processes and contribute to the development of targeted therapies.
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Anand R, Kashif M, Pandit A, Babu R, Singh AP. Reprogramming in Candida albicans Gene Expression Network under Butanol Stress Abrogates Hyphal Development. Int J Mol Sci 2023; 24:17227. [PMID: 38139056 PMCID: PMC10743114 DOI: 10.3390/ijms242417227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 11/02/2023] [Accepted: 11/03/2023] [Indexed: 12/24/2023] Open
Abstract
Candida albicans is the causative agent of invasive fungal infections. Its hyphae-forming ability is regarded as one of the important virulence factors. To unravel the impact of butanol on Candida albicans, it was placed in O+ve complete human serum with butanol (1% v/v). The Candida transcriptome under butanol stress was then identified by mRNA sequencing. Studies including electron microscopy demonstrated the inhibition of hyphae formation in Candida under the influence of butanol, without any significant alteration in growth rate. The numbers of genes upregulated in the butanol in comparison to the serum alone were 1061 (20 min), 804 (45 min), and 537 (120 min). Candida cells exhibited the downregulation of six hypha-specific transcription factors and the induction of four repressor/regulator genes. Many of the hypha-specific genes exhibited repression in the medium with butanol. The genes related to adhesion also exhibited repression, whereas, among the heat-shock genes, three showed inductions in the presence of butanol. The fungal-specific genes exhibited induction as well as repression in the butanol-treated Candida cells. Furthermore, ten upregulated genes formed the core stress gene set in the presence of butanol. In the gene ontology analysis, enrichment of the processes related to non-coding RNA, ribosome biosynthesis, and metabolism was observed in the induced gene set. On the other side, a few GO biological process terms, including biofilm formation and filamentous growth, were enriched in the repressed gene set. Taken together, under butanol stress, Candida albicans is unable to extend hyphae and shows growth by budding. Many of the genes with perturbed expression may have fitness or virulence attributes and may provide prospective sites of antifungal targets against C. albicans.
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Affiliation(s)
- Rajesh Anand
- Infectious Disease Laboratory, National Institute of Immunology, New Delhi 110067, India; (R.A.)
| | - Mohammad Kashif
- Infectious Disease Laboratory, National Institute of Immunology, New Delhi 110067, India; (R.A.)
| | - Awadhesh Pandit
- Next Generation Sequencing Facility, National Institute of Immunology, New Delhi 110067, India
| | - Ram Babu
- Department of Botany, Kirori Mal College, University of Delhi, Delhi 110007, India
| | - Agam P. Singh
- Infectious Disease Laboratory, National Institute of Immunology, New Delhi 110067, India; (R.A.)
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David H, Solomon AP. Molecular association of Candida albicans and vulvovaginal candidiasis: focusing on a solution. Front Cell Infect Microbiol 2023; 13:1245808. [PMID: 37900321 PMCID: PMC10611527 DOI: 10.3389/fcimb.2023.1245808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 09/21/2023] [Indexed: 10/31/2023] Open
Abstract
Candida albicans-mediated vulvovaginal candidiasis (VVC) is a significant challenge in clinical settings, owing to the inefficacy of current antifungals in modulating virulence, development of resistance, and poor penetration into the biofilm matrix. Various predisposition factors are molecular drivers that lead to the dysbiosis of normal microflora of the vagina, upregulation of central metabolic pathways, morphogenesis, hyphal extension, adhesion, invasion, and biofilm formation leading to chronic infection and recurrence. Hence, it is crucial to understand the molecular mechanism behind the virulence pathways driven by those drivers to decode the drug targets. Finding innovative solutions targeting fungal virulence/biofilm may potentiate the antifungals at low concentrations without affecting the recurrence of resistance. With this background, the present review details the critical molecular drivers and associated network of virulence pathways, possible drug targets, target-specific inhibitors, and probable mode of drug delivery to cross the preclinical phase by appropriate in vivo models.
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Affiliation(s)
| | - Adline Princy Solomon
- Quorum Sensing Laboratory, Centre for Research in Infectious Diseases (CRID), School of Chemical and Biotechnology, SASTRA Deemed to be University, Thanjavur, India
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Zeng G, Neo SP, Pang LM, Gao J, Chong SC, Gunaratne J, Wang Y. Comprehensive Interactome Analysis for the Sole Adenylyl Cyclase Cyr1 of Candida albicans. Microbiol Spectr 2022; 10:e0393422. [PMID: 36314909 PMCID: PMC9769623 DOI: 10.1128/spectrum.03934-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 10/06/2022] [Indexed: 11/06/2022] Open
Abstract
Cyr1, the sole adenylyl cyclase of the fungal pathogen Candida albicans, is a central component of the cAMP/protein kinase A signaling pathway that controls the yeast-to-hypha transition. Cyr1 is a multivalent sensor and integrator of various external and internal signals. To better understand how these signals are relayed to Cyr1 to regulate its activity, we sought to establish the interactome of Cyr1 by using stable isotope labeling by amino acids in cell culture (SILAC)-based quantitative proteomics to identify the proteins that coimmunoprecipitated with Cyr1. The method identified 36 proteins as candidates for authentic Cyr1-interacting partners, together with two known Cyr1-binding proteins, Cap1 and Act1. Fourteen identified proteins belonged to three functional groups, including actin regulation, cell wall components, and mitochondrial activities, that are known to play important roles in cell morphogenesis. To validate the proteomics data, we used biochemical and genetic methods to characterize two cell wall-related proteins, Mp65 and Sln1. First, coimmunoprecipitation confirmed their physical association with Cyr1. Second, deleting either MP65 or SLN1 resulted in severe defects in filamentation on serum plates. This study establishes the first Cyr1 interactome and uncovers a potential role for cell wall proteins in directly regulating Cyr1 activity to determine growth forms in C. albicans. IMPORTANCE A critical virulence trait of the human fungal pathogen Candida albicans is its ability to undergo the yeast-to-hypha transition in response to diverse environmental and cellular stimuli. Previous studies suggested that the sole adenylyl cyclase of C. albicans, Cyr1, is a multivalent signal sensor and integrator synthesizing cAMP to activate the downstream hypha-promoting events through the cAMP/protein kinase A pathway. To fully understand how Cyr1 senses and processes multiple stimuli to generate appropriate signal outputs, it was necessary to identify and characterize Cyr1-interacting partners. This study employed SILAC-based quantitative proteomic approaches and identified 36 Cyr1-associated proteins, many having functions associated with hyphal morphogenesis. Coimmunoprecipitation verified two cell surface proteins, Mp65 and Sln1. Furthermore, genetic and phenotypic analyses demonstrated the cAMP-dependent roles of these two proteins in determining hyphal growth. Our study establishes the first Cyr1 interactome and uncovers new Cyr1 regulators that mediate cell surface signals to influence the growth mode of C. albicans.
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Affiliation(s)
| | - Suat Peng Neo
- Quantitative Proteomics Group, Institute of Molecular and Cell Biology, Singapore
| | | | | | | | - Jayantha Gunaratne
- Quantitative Proteomics Group, Institute of Molecular and Cell Biology, Singapore
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Yue Wang
- Infectious Diseases Labs, Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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Rivera-Yañez CR, Ruiz-Hurtado PA, Reyes-Reali J, Mendoza-Ramos MI, Vargas-Díaz ME, Hernández-Sánchez KM, Pozo-Molina G, Méndez-Catalá CF, García-Romo GS, Pedroza-González A, Méndez-Cruz AR, Nieto-Yañez O, Rivera-Yañez N. Antifungal Activity of Mexican Propolis on Clinical Isolates of Candida Species. Molecules 2022; 27:molecules27175651. [PMID: 36080417 PMCID: PMC9457601 DOI: 10.3390/molecules27175651] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 08/24/2022] [Accepted: 08/30/2022] [Indexed: 11/16/2022] Open
Abstract
Infections caused by micro-organisms of the genus Candida are becoming a growing health problem worldwide. These fungi are opportunistic commensals that can produce infections—clinically known as candidiasis—in immunocompromised individuals. The indiscriminate use of different anti-fungal treatments has triggered the resistance of Candida species to currently used therapies. In this sense, propolis has been shown to have potent antimicrobial properties and thus can be used as an approach for the inhibition of Candida species. Therefore, this work aims to evaluate the anti-Candida effects of a propolis extract obtained from the north of Mexico on clinical isolates of Candida species. Candida species were specifically identified from oral lesions, and both the qualitative and quantitative anti-Candida effects of the Mexican propolis were evaluated, as well as its inhibitory effect on C. albicans isolate’s germ tube growth and chemical composition. Three Candida species were identified, and our results indicated that the inhibition halos of the propolis ranged from 7.6 to 21.43 mm, while that of the MFC and FC50 ranged from 0.312 to 1.25 and 0.014 to 0.244 mg/mL, respectively. Moreover, the propolis was found to inhibit germ tube formation (IC50 ranging from 0.030 to 1.291 mg/mL). Chemical composition analysis indicated the presence of flavonoids, including pinocembrin, baicalein, pinobanksin chalcone, rhamnetin, and biochanin A, in the Mexican propolis extract. In summary, our work shows that Mexican propolis presents significant anti-Candida effects related to its chemical composition, and also inhibits germ tube growth. Other Candida species virulence factors should be investigated in future research in order to determine the mechanisms associated with antifungal effects against them.
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Affiliation(s)
- Claudia Rebeca Rivera-Yañez
- Carrera de Médico Cirujano, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de Mexico, Tlalnepantla 54090, Mexico
- Unidad de Morfofisiología y Función, Laboratorio de Inmunología, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de Mexico, Tlalnepantla 54090, Mexico
| | - Porfirio Alonso Ruiz-Hurtado
- Laboratorio de Toxicología de Productos Naturales, Departamento de Farmacia, Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Av. Wilfrido Massieu, Gustavo A. Madero 07738, Mexico
| | - Julia Reyes-Reali
- Carrera de Médico Cirujano, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de Mexico, Tlalnepantla 54090, Mexico
- Unidad de Morfofisiología y Función, Laboratorio de Inmunología, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de Mexico, Tlalnepantla 54090, Mexico
| | - María Isabel Mendoza-Ramos
- Carrera de Médico Cirujano, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de Mexico, Tlalnepantla 54090, Mexico
- Unidad de Morfofisiología y Función, Laboratorio de Inmunología, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de Mexico, Tlalnepantla 54090, Mexico
| | - María Elena Vargas-Díaz
- Laboratorio de Química de Productos Naturales, Departamento de Química Orgánica, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Prol. de Carpio y Plan de Ayala, Ciudad de México 11340, Mexico
| | - Karla Mariela Hernández-Sánchez
- Laboratorio de Química de Productos Naturales, Departamento de Química Orgánica, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Prol. de Carpio y Plan de Ayala, Ciudad de México 11340, Mexico
| | - Glustein Pozo-Molina
- Carrera de Médico Cirujano, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de Mexico, Tlalnepantla 54090, Mexico
- Laboratorio de Genética y Oncología Molecular, Laboratorio 5, Edificio A4, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de Mexico, Tlalnepantla 54090, Mexico
| | - Claudia Fabiola Méndez-Catalá
- Laboratorio de Genética y Oncología Molecular, Laboratorio 5, Edificio A4, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de Mexico, Tlalnepantla 54090, Mexico
- División de Investigación y Posgrado, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de Mexico, Tlalnepantla 54090, Mexico
| | - Gina Stella García-Romo
- Carrera de Médico Cirujano, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de Mexico, Tlalnepantla 54090, Mexico
- Unidad de Morfofisiología y Función, Laboratorio de Inmunología, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de Mexico, Tlalnepantla 54090, Mexico
| | - Alexander Pedroza-González
- Carrera de Médico Cirujano, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de Mexico, Tlalnepantla 54090, Mexico
- Unidad de Morfofisiología y Función, Laboratorio de Inmunología, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de Mexico, Tlalnepantla 54090, Mexico
| | - Adolfo René Méndez-Cruz
- Carrera de Médico Cirujano, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de Mexico, Tlalnepantla 54090, Mexico
- Unidad de Morfofisiología y Función, Laboratorio de Inmunología, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de Mexico, Tlalnepantla 54090, Mexico
| | - Oscar Nieto-Yañez
- Carrera de Médico Cirujano, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de Mexico, Tlalnepantla 54090, Mexico
- Correspondence: (O.N.-Y.); (N.R.-Y.); Tel.: +52-5522-476-721 (N.R.-Y.)
| | - Nelly Rivera-Yañez
- Carrera de Médico Cirujano, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de Mexico, Tlalnepantla 54090, Mexico
- División de Investigación y Posgrado, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de Mexico, Tlalnepantla 54090, Mexico
- Correspondence: (O.N.-Y.); (N.R.-Y.); Tel.: +52-5522-476-721 (N.R.-Y.)
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An Integrated Analysis of Intracellular Metabolites and Virulence Gene Expression during Biofilm Development of a Clinical Isolate of Candida tropicalis on Distinct Surfaces. Int J Mol Sci 2021; 22:ijms22169038. [PMID: 34445744 PMCID: PMC8396647 DOI: 10.3390/ijms22169038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 08/19/2021] [Indexed: 11/18/2022] Open
Abstract
Emergence of Candida tropicalis, which causes potential life-threatening invasive candidiasis, is often associated with colonization of medical devices as biofilm. Biofilm plays an important role in the virulence of the pathogen because of its complex structure, which provides resistance to conventional antimicrobials. In this study, the metabolic response of a clinical strain of C. tropicalis colonizing three distinct surfaces (polytetrafluoroethylene (PTFE), polystyrene, and polycarbonate) as well as the expression of virulence and stress related genes (ALS3, Hsp21, SAP1, SAP2, SAP3, and CYR1), were explored. Our results showed that lesser biofilm was developed on PTFE compared to polystyrene and polycarbonate. GS-MS metabolic analysis identified a total of 36 metabolites in the intracellular extract of cells grown on polystyrene, polycarbonate, and PTFE, essentially belonging to central carbon metabolism, amino acids, and lipids metabolism. The metabolic analysis showed that saturated and unsaturated fatty acids are preferentially produced during biofilm development on polycarbonate, whereas trehalose and vitamin B6, known as cellular protectors against a variety of stressors, were characteristic of biofilm on PTFE. The results of the transcriptomic analysis consider the different degrees of colonization of the three substrates, being CYR1, which encodes the component of signaling pathway of hyphal formation-cAMP-PKA, downregulated in PTFE biofilm compared to polycarbonate or polystyrene biofilms, while Hsp21 was upregulated in concomitance with the potential unfavorable conditions for biofilm formation on PTFE. Overall, this work provides new insights into the knowledge of C. tropicalis biofilm development on surfaces of medical relevance in the perspective of improving the management of Candida infections.
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Chow EWL, Pang LM, Wang Y. From Jekyll to Hyde: The Yeast-Hyphal Transition of Candida albicans. Pathogens 2021; 10:pathogens10070859. [PMID: 34358008 PMCID: PMC8308684 DOI: 10.3390/pathogens10070859] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 06/30/2021] [Accepted: 07/05/2021] [Indexed: 12/22/2022] Open
Abstract
Candida albicans is a major fungal pathogen of humans, accounting for 15% of nosocomial infections with an estimated attributable mortality of 47%. C. albicans is usually a benign member of the human microbiome in healthy people. Under constant exposure to highly dynamic environmental cues in diverse host niches, C. albicans has successfully evolved to adapt to both commensal and pathogenic lifestyles. The ability of C. albicans to undergo a reversible morphological transition from yeast to filamentous forms is a well-established virulent trait. Over the past few decades, a significant amount of research has been carried out to understand the underlying regulatory mechanisms, signaling pathways, and transcription factors that govern the C. albicans yeast-to-hyphal transition. This review will summarize our current understanding of well-elucidated signal transduction pathways that activate C. albicans hyphal morphogenesis in response to various environmental cues and the cell cycle machinery involved in the subsequent regulation and maintenance of hyphal morphogenesis.
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Affiliation(s)
- Eve Wai Ling Chow
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Proteos, Singapore 138673, Singapore;
| | - Li Mei Pang
- National Dental Centre Singapore, National Dental Research Institute Singapore (NDRIS), 5 Second Hospital Ave, Singapore 168938, Singapore;
| | - Yue Wang
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Proteos, Singapore 138673, Singapore;
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Drive, Singapore 117597, Singapore
- Correspondence:
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Wang M, Feng LR, Li ZL, Ma KG, Chang KW, Chen XL, Yang PB, Ji SF, Ma YB, Han H, Ruganzua JB, Yang WN, Qian YH. Thymosin β4 reverses phenotypic polarization of glial cells and cognitive impairment via negative regulation of NF-κB signaling axis in APP/PS1 mice. J Neuroinflammation 2021; 18:146. [PMID: 34183019 PMCID: PMC8240373 DOI: 10.1186/s12974-021-02166-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 05/04/2021] [Indexed: 01/15/2023] Open
Abstract
Background Thymosin β4 (Tβ4) is the most abundant member of the β-thymosins and plays an important role in the control of actin polymerization in eukaryotic cells. While its effects in multiple organs and diseases are being widely investigated, the safety profile has been established in animals and humans, currently, little is known about its influence on Alzheimer’s disease (AD) and the possible mechanisms. Thus, we aimed to evaluate the effects and mechanisms of Tβ4 on glial polarization and cognitive performance in APP/PS1 transgenic mice. Methods Behavior tests were conducted to assess the learning and memory, anxiety and depression in APP/PS1 mice. Thioflavin S staining, Nissl staining, immunohistochemistry/immunofluorescence, ELISA, qRT-PCR, and immunoblotting were performed to explore Aβ accumulation, phenotypic polarization of glial cells, neuronal loss and function, and TLR4/NF-κB axis in APP/PS1 mice. Results We demonstrated that Tβ4 protein level elevated in all APP/PS1 mice. Over-expression of Tβ4 alone alleviated AD-like phenotypes of APP/PS1 mice, showed less brain Aβ accumulation and more Insulin-degrading enzyme (IDE), reversed phenotypic polarization of microglia and astrocyte to a healthy state, improved neuronal function and cognitive behavior performance, and accidentally displayed antidepressant-like effect. Besides, Tβ4 could downregulate both TLR4/MyD88/NF-κB p65 and p52-dependent inflammatory pathways in the APP/PS1 mice. While combination drug of TLR4 antagonist TAK242 or NF-κB p65 inhibitor PDTC exerted no further effects. Conclusions These results suggest that Tβ4 may exert its function by regulating both classical and non-canonical NF-κB signaling and is restoring its function as a potential therapeutic target against AD. Supplementary Information The online version contains supplementary material available at 10.1186/s12974-021-02166-3.
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Affiliation(s)
- Meng Wang
- Department of Human Anatomy and Histology-Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, Shaanxi, China.,Institute of Neuroscience, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China
| | - Li-Rong Feng
- Department of Human Anatomy and Histology-Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, Shaanxi, China.,Institute of Neuroscience, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China
| | - Zi-Long Li
- Department of Human Anatomy and Histology-Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, Shaanxi, China.,Institute of Neuroscience, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China
| | - Kai-Ge Ma
- Institute of Neuroscience, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, Shaanxi, China.,Institute of Neurobiology, Xi'an Jiaotong University Health Science Center, Xi'an, China
| | - Ke-Wei Chang
- Department of Human Anatomy and Histology-Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, Shaanxi, China.,Institute of Neuroscience, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, Shaanxi, China
| | - Xin-Lin Chen
- Institute of Neuroscience, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, Shaanxi, China.,Institute of Neurobiology, Xi'an Jiaotong University Health Science Center, Xi'an, China
| | - Peng-Bo Yang
- Department of Human Anatomy and Histology-Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, Shaanxi, China.,Institute of Neuroscience, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, Shaanxi, China
| | - Sheng-Feng Ji
- Department of Human Anatomy and Histology-Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, Shaanxi, China.,Institute of Neuroscience, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, Shaanxi, China
| | - Yan-Bing Ma
- Department of Human Anatomy and Histology-Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, Shaanxi, China.,Institute of Neuroscience, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, Shaanxi, China
| | - Hua Han
- Department of Human Anatomy and Histology-Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, Shaanxi, China.,Institute of Neuroscience, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, Shaanxi, China
| | - John Bosco Ruganzua
- Department of Human Anatomy and Histology-Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, Shaanxi, China.,Institute of Neuroscience, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China
| | - Wei-Na Yang
- Department of Human Anatomy and Histology-Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, Shaanxi, China.,Institute of Neuroscience, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China.,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, Shaanxi, China
| | - Yi-Hua Qian
- Department of Human Anatomy and Histology-Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, Shaanxi, China. .,Institute of Neuroscience, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, China. .,Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an Jiaotong University Health Science Center, 76 Yanta West Road, Xi'an, 710061, Shaanxi, China.
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10
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Kanchanapiboon J, Kongsa U, Pattamadilok D, Kamponchaidet S, Wachisunthon D, Poonsatha S, Tuntoaw S. Boesenbergia rotunda extract inhibits Candida albicans biofilm formation by pinostrobin and pinocembrin. JOURNAL OF ETHNOPHARMACOLOGY 2020; 261:113193. [PMID: 32730867 DOI: 10.1016/j.jep.2020.113193] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 07/09/2020] [Accepted: 07/14/2020] [Indexed: 06/11/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Boesenbergia rotunda (L.) Mansf. (Zingiberaceae) is an indigenous plant of Southeast Asia. Based on ethnopharmacological use, the rhizome is recommended in the treatment of stomachache, leukoplakia, abscesses, and leukorrhea in Thailand primary health care system. Candida albicans often causes leukorrhea, and infection of many mucosal sites. Its infection leads to serious illness. AIM OF THE STUDY This study aimed to investigate the effects of the ethanolic extract of the B. rotunda rhizome on C. albicans ATCC10231 in the stages of planktonic and biofilm formation and to explore the underlying mechanisms. MATERIALS AND METHODS The chemical composition of the extract was determined using ultra-performance liquid chromatography (UPLC). The planktonic growth of C. albicans was evaluated by the microdilution method, following EUCAST guidelines. For each stage of biofilm formation, the biofilm was assessed by the MTT assay. The biofilm structure was examined under a light microscope. The degree of cell surface hydrophobicity was measured. The mRNA levels of ALS1, ALS3, and ACT1 were determined by RT-qPCR. RESULTS The extract of B. rotunda consisted of 25% (w/w) pinostrobin and 12% (w/w) pinocembrin. All stages of C. albicans biofilm formation were significantly inhibited by the extract, whereas the planktonic growth did not change. Biofilm development greatly decreased due to the extract in a concentration-dependent manner, with an IC50 value of 17.7 μg/mL. Pinostrobin and pinocembrin demonstrated inhibitory effects during this stage. These results were in accordance with the microscopic evaluation. The filamentous form decreased with pinocembrin rather than pinostrobin. Moreover, the cell surface hydrophobicity was significantly decreased by 6.25 and 12.5 μg/mL of the extract and 100 μM of pinocembrin. The ALS3 mRNA level was noticeably decreased by 12.5 μg/mL of the extract, 100 μM of pinostrobin, and 100 μM of pinocembrin. The ACT1 mRNA level decreased significantly with pinocembrin. However, the ALS1 mRNA level was not altered following all treatments. CONCLUSION The ethanolic extract of B. rotunda could inhibit biofilm formation of C. albicans, especially during the biofilm development stage, by means of reducing the cell surface hydrophobicity and suppressing the ALS3 mRNA expression. Pinocembrin had a stronger effect on ALS3 mRNA expression than pinostrobin. Only pinocembrin significantly decreased the ACT1 mRNA level.
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Affiliation(s)
- Jamras Kanchanapiboon
- Medicinal Plant Research Institute, Department of Medical Sciences, Ministry of Public Health, Nonthaburi, 11000, Thailand.
| | - Ubonphan Kongsa
- Medicinal Plant Research Institute, Department of Medical Sciences, Ministry of Public Health, Nonthaburi, 11000, Thailand
| | - Duangpen Pattamadilok
- Medicinal Plant Research Institute, Department of Medical Sciences, Ministry of Public Health, Nonthaburi, 11000, Thailand
| | - Sunisa Kamponchaidet
- Medicinal Plant Research Institute, Department of Medical Sciences, Ministry of Public Health, Nonthaburi, 11000, Thailand
| | - Detmontree Wachisunthon
- Medicinal Plant Research Institute, Department of Medical Sciences, Ministry of Public Health, Nonthaburi, 11000, Thailand
| | - Subhadhcha Poonsatha
- Medicinal Plant Research Institute, Department of Medical Sciences, Ministry of Public Health, Nonthaburi, 11000, Thailand
| | - Sasiwan Tuntoaw
- Medicinal Plant Research Institute, Department of Medical Sciences, Ministry of Public Health, Nonthaburi, 11000, Thailand
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11
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Truong T, Pang LM, Rajan S, Wong SSW, Fung YME, Samaranayake L, Seneviratne CJ. The Proteome of Community Living Candida albicans Is Differentially Modulated by the Morphologic and Structural Features of the Bacterial Cohabitants. Microorganisms 2020; 8:microorganisms8101541. [PMID: 33036329 PMCID: PMC7601143 DOI: 10.3390/microorganisms8101541] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 10/02/2020] [Accepted: 10/03/2020] [Indexed: 11/16/2022] Open
Abstract
Candida albicans is a commensal polymorphic and opportunistic fungus, which usually resides as a small community in the oral cavities of a majority of humans. The latter eco-system presents this yeast varied opportunities for mutualistic interactions with other cohabitant oral bacteria, that synergizes its persistence and pathogenicity. Collectively, these communities live within complex plaque biofilms which may adversely affect the oral health and increase the proclivity for oral candidiasis. The proteome of such oral biofilms with myriad interkingdom interactions are largely underexplored. Herein, we employed limma differential expression analysis, and cluster analysis to explore the proteomic interactions of C. albicans biofilms with nine different common oral bacterial species, Aggregatibacter actinomycetemcomitans, Actinomyces naeslundii, Fusobacterium nucleatum, Enterococcus faecalis, Porphyromonas gingivalis, Streptococcus mutants, Streptococcus sanguinis, Streptococcus mitis, and Streptococcus sobrinus. Interestingly, upon exposure of C. albicans biofilms to the foregoing heat-killed bacteria, the proteomes of the fungus associated with cellular respiration, translation, oxidoreductase activity, and ligase activity were significantly altered. Subsequent differential expression and cluster analysis revealed the subtle, yet significant alterations in the C. albicans proteome, particularly on exposure to bacteria with dissimilar cell morphologies, and Gram staining characteristics.
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Affiliation(s)
- Thuyen Truong
- Oral Sciences, Faculty of Dentistry, National University of Singapore, Singapore 119085, Singapore;
| | - Li Mei Pang
- National Dental Research Institute Singapore (NDRIS), National Dental Centre Singapore, Singapore 168938, Singapore;
| | - Suhasini Rajan
- Walther Straub Institute of Pharmacology and Toxicology, Member of the German Center for Lung Research (DZL), Medical Faculty, LMU-Munich, 80336 Munich, Germany;
| | - Sarah Sze Wah Wong
- Molecular Mycology Unit, Institut Pasteur, CNRS, UMR2000, 10098 Paris, France;
| | - Yi Man Eva Fung
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China;
| | - Lakshman Samaranayake
- College of Dental Medicine, University of Sharjah, Sharjah 27272, UAE;
- Faculty of Dentistry, The University of Hong Kong, Hong Kong, China
| | - Chaminda Jayampath Seneviratne
- National Dental Research Institute Singapore (NDRIS), National Dental Centre Singapore, Singapore 168938, Singapore;
- Oral Health Academic Clinical Programme, Duke-NUS Medical School, Singapore 169857, Singapore
- Correspondence: ; Tel.: +65-65767141
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12
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Moriwaki-Takano M, Iwakura R, Hoshino K. Dimorphic Mechanism on cAMP Mediated Signal Pathway in Mucor circinelloides. Appl Biochem Biotechnol 2020; 193:1252-1265. [PMID: 32424738 DOI: 10.1007/s12010-020-03342-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 04/23/2020] [Indexed: 11/27/2022]
Abstract
Mucor circinelloides is a dimorphic fungus that is a non-pathogen strain belonging to zygomycetes. In this research, a part of hypothetical mechanism on yeast-like cell induction of M. circinelloides in CO2 atmosphere was reported from the viewpoint of gene expression. To explain the relation between the change and the expressions of some genes involved in morphological changes of the strain, these were analyzed on the filamentous and yeast cell by real-time qPCR. The compared genes were Nce103, Ras3, Cyr1, Pde, and Efg1 encoding carbonic anhydrase, GTPase, adenylate cyclase, phosphodiesterase, and elongation factor G1, respectively. In anaerobic grown yeast cell with 70%N2 + 30%CO2, the Nce103 and Ras3 gene expressions decreased to 24 h whereas that of the filamentous cell increased. However, a downstream gene of Cyr1 expression level in the yeast cell was higher than that of filamentous cell. A lower level of Pde in the yeast cell than that of the filamentous cell indicated intracellular cAMP accumulation. The actual cAMP in the yeast cell remained whereas that of the filamentous cell decreased with cultivation. The Efg1 expression level controlling hyphal elongation was suppressed in the yeast cell. The intracellular cAMP accumulation and Efg1 expression regulate hyphal elongation or yeast forming.
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Affiliation(s)
- Maki Moriwaki-Takano
- Graduate School of Science and Engineering, University of Toyama, Gofuku 3190, Toyama, Japan
| | - Ryo Iwakura
- Graduate School of Science and Engineering, University of Toyama, Gofuku 3190, Toyama, Japan
| | - Kazuhiro Hoshino
- Graduate School of Science and Engineering, University of Toyama, Gofuku 3190, Toyama, Japan.
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13
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Schoeters F, Van Dijck P. Protein-Protein Interactions in Candida albicans. Front Microbiol 2019; 10:1792. [PMID: 31440220 PMCID: PMC6693483 DOI: 10.3389/fmicb.2019.01792] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 07/19/2019] [Indexed: 12/27/2022] Open
Abstract
Despite being one of the most important human fungal pathogens, Candida albicans has not been studied extensively at the level of protein-protein interactions (PPIs) and data on PPIs are not readily available in online databases. In January 2018, the database called "Biological General Repository for Interaction Datasets (BioGRID)" that contains the most PPIs for C. albicans, only documented 188 physical or direct PPIs (release 3.4.156) while several more can be found in the literature. Other databases such as the String database, the Molecular INTeraction Database (MINT), and the Database for Interacting Proteins (DIP) database contain even fewer interactions or do not even include C. albicans as a searchable term. Because of the non-canonical codon usage of C. albicans where CUG is translated as serine rather than leucine, it is often problematic to use the yeast two-hybrid system in Saccharomyces cerevisiae to study C. albicans PPIs. However, studying PPIs is crucial to gain a thorough understanding of the function of proteins, biological processes and pathways. PPIs can also be potential drug targets. To aid in creating PPI networks and updating the BioGRID, we performed an exhaustive literature search in order to provide, in an accessible format, a more extensive list of known PPIs in C. albicans.
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Affiliation(s)
- Floris Schoeters
- VIB-KU Leuven Center for Microbiology, Leuven, Belgium
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Leuven, Belgium
| | - Patrick Van Dijck
- VIB-KU Leuven Center for Microbiology, Leuven, Belgium
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Leuven, Belgium
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14
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Zhu W, Xu X, Peng F, Yan DZ, Zhang S, Xu R, Wu J, Li X, Wei W, Chen W. The cyclase-associated protein ChCAP is important for regulation of hyphal growth, appressorial development, penetration, pathogenicity, conidiation, intracellular cAMP level, and stress tolerance in Colletotrichum higginsianum. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2019; 283:1-10. [PMID: 31128679 DOI: 10.1016/j.plantsci.2019.02.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 02/20/2019] [Accepted: 02/22/2019] [Indexed: 06/09/2023]
Abstract
Colletotrichum higginsianum causes anthracnose disease in a wide range of cruciferous crops and has been used as a model system to study plant-pathogen interactions and pathogenicity of hemibiotrophic plant pathogens. Conidiation, hyphae growth, appressorial development and appressorial penetration are significant steps during the infection process of C. higginsianum. However, the mechanisms of these important steps during infection remain incompletely understood. To further investigate the mechanisms of the plant-C. higginsianum interactions during infection progress, we characterized Cyclase-Associated Protein (ChCAP) gene. Deletion of the ChCAP gene resulted in reduction in conidiation and hyphal growth rate. The pathogenicity of ΔChCAP mutants was significantly reduced with much smaller lesion on the infected leaves compared to that of wild type strain with typically water-soaked and dark necrotic lesions on Arabidopsis leaves. Further study demonstrated that the appressorial formation rate, turgor pressure, penetration ability and switch from biotrophic to necrotrophic phases decreased obviously in ΔChCAP mutants, indicating that the attenuated pathogenicity of ΔChCAP mutants was due to these defective phenotypes. In addition, the ΔChCAP mutants sectored on PDA with abnormal, dark color, vesicle-like colony morphology and hyphae tip. Moreover, the ΔChCAP mutants had a reduced intracellular cAMP levels and exogenous cAMP can partially rescue the defects of ΔChCAP mutants in appressorial formation and penetration rate, but not in colony morphology, conidial shape and virulence, indicating that ChCAP is a key component in cAMP signaling pathway and likely play other roles in biology of C. higginsianum. In summary, our findings support the role of ChCAP in regulating conidiation, intracellular cAMP level, hyphal growth, appressorial formation, penetration ability and pathogenicity of this hemibiotrophic fungus.
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Affiliation(s)
- Wenjun Zhu
- College of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan 430023, People's Republic of China
| | - Xiaowen Xu
- Hubei Academy of Forestry, Wuhan 430075, People's Republic of China
| | - Fang Peng
- College of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan 430023, People's Republic of China
| | - Da-Zhong Yan
- College of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan 430023, People's Republic of China
| | - Shaopeng Zhang
- College of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan 430023, People's Republic of China
| | - Ran Xu
- College of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan 430023, People's Republic of China
| | - Jing Wu
- College of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan 430023, People's Republic of China
| | - Xin Li
- College of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan 430023, People's Republic of China
| | - Wei Wei
- Department of Plant Pathology, Washington State University, United States Department of Agriculture-Agricultural Research Service, Washington State University, Pullman 99164, USA.
| | - Weidong Chen
- Department of Plant Pathology, Washington State University, United States Department of Agriculture-Agricultural Research Service, Washington State University, Pullman 99164, USA.
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15
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Hasan R, Zhou GL. The Cytoskeletal Protein Cyclase-Associated Protein 1 (CAP1) in Breast Cancer: Context-Dependent Roles in Both the Invasiveness and Proliferation of Cancer Cells and Underlying Cell Signals. Int J Mol Sci 2019; 20:E2653. [PMID: 31151140 PMCID: PMC6600220 DOI: 10.3390/ijms20112653] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Revised: 05/20/2019] [Accepted: 05/28/2019] [Indexed: 12/22/2022] Open
Abstract
As a conserved actin-regulating protein, CAP (adenylyl Cyclase-Associated Protein) functions to facilitate the rearrangement of the actin cytoskeleton. The ubiquitously expressed isoform CAP1 drives mammalian cell migration, and accordingly, most studies on the involvement of CAP1 in human cancers have largely been based on the rationale that up-regulated CAP1 will stimulate cancer cell migration and invasiveness. While findings from some studies reported so far support this case, lines of evidence largely from our recent studies point to a more complex and profound role for CAP1 in the invasiveness of cancer cells, where the potential activation of cell adhesion signaling is believed to play a key role. Moreover, CAP1 was also found to control proliferation in breast cancer cells, through the regulation of ERK (External signal-Regulated Kinase). Alterations in the activities of FAK (Focal Adhesion Kinase) and ERK from CAP1 depletion that are consistent to the opposite adhesion and proliferation phenotypes were detected in the metastatic and non-metastatic breast cancer cells. In this review, we begin with the overview of the literature on CAP, by highlighting the molecular functions of mammalian CAP1 in regulating the actin cytoskeleton and cell adhesion. We will next discuss the role of the FAK/ERK axis, and possibly Rap1, in mediating CAP1 signals to control breast cancer cell adhesion, invasiveness, and proliferation, largely based on our latest findings. Finally, we will discuss the relevance of these novel mechanistic insights to ultimately realizing the translational potential of CAP1 in targeted therapeutics for breast cancer.
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Affiliation(s)
- Rokib Hasan
- Molecular Biosciences Graduate Program, Arkansas State University, State University, AR 72467, USA.
| | - Guo-Lei Zhou
- Molecular Biosciences Graduate Program, Arkansas State University, State University, AR 72467, USA.
- Department of Biological Sciences, Arkansas State University, State University, AR 72467, USA.
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16
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Regulation of Candida albicans Hyphal Morphogenesis by Endogenous Signals. J Fungi (Basel) 2019; 5:jof5010021. [PMID: 30823468 PMCID: PMC6463138 DOI: 10.3390/jof5010021] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 02/25/2019] [Accepted: 02/26/2019] [Indexed: 12/15/2022] Open
Abstract
Candida albicans is a human commensal fungus that is able to assume several morphologies, including yeast, hyphal, and pseudohyphal. Under a range of conditions, C. albicans performs a regulated switch to the filamentous morphology, characterized by the emergence of a germ tube from the yeast cell, followed by a mold-like growth of branching hyphae. This transition from yeast to hyphal growth has attracted particular attention, as it has been linked to the virulence of C. albicans as an opportunistic human pathogen. Signal transduction pathways that mediate the induction of the hyphal transcription program upon the imposition of external stimuli have been extensively investigated. However, the hyphal morphogenesis transcription program can also be induced by internal cellular signals, such as inhibition of cell cycle progression, and conversely, the inhibition of hyphal extension can repress hyphal-specific gene expression, suggesting that endogenous cellular signals are able to modulate hyphal gene expression as well. Here we review recent developments in the regulation of the hyphal morphogenesis of C. albicans, with emphasis on endogenous morphogenetic signals.
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17
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Sharma J, Rosiana S, Razzaq I, Shapiro RS. Linking Cellular Morphogenesis with Antifungal Treatment and Susceptibility in Candida Pathogens. J Fungi (Basel) 2019; 5:E17. [PMID: 30795580 PMCID: PMC6463059 DOI: 10.3390/jof5010017] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 02/11/2019] [Accepted: 02/13/2019] [Indexed: 02/07/2023] Open
Abstract
Fungal infections are a growing public health concern, and an increasingly important cause of human mortality, with Candida species being amongst the most frequently encountered of these opportunistic fungal pathogens. Several Candida species are polymorphic, and able to transition between distinct morphological states, including yeast, hyphal, and pseudohyphal forms. While not all Candida pathogens are polymorphic, the ability to undergo morphogenesis is linked with the virulence of many of these pathogens. There are also many connections between Candida morphogenesis and antifungal drug treatment and susceptibility. Here, we review how Candida morphogenesis-a key virulence trait-is linked with antifungal drugs and antifungal drug resistance. We highlight how antifungal therapeutics are able to modulate morphogenesis in both sensitive and drug-resistant Candida strains, the shared signaling pathways that mediate both morphogenesis and the cellular response to antifungal drugs and drug resistance, and the connection between Candida morphology, drug resistance, and biofilm growth. We further review the development of anti-virulence drugs, and targeting Candida morphogenesis as a novel therapeutic strategy to target fungal pathogens. Together, this review highlights important connections between fungal morphogenesis, virulence, and susceptibility to antifungals.
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Affiliation(s)
- Jehoshua Sharma
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
| | - Sierra Rosiana
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
| | - Iqra Razzaq
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
| | - Rebecca S Shapiro
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
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18
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Silao FGS, Ward M, Ryman K, Wallström A, Brindefalk B, Udekwu K, Ljungdahl PO. Mitochondrial proline catabolism activates Ras1/cAMP/PKA-induced filamentation in Candida albicans. PLoS Genet 2019; 15:e1007976. [PMID: 30742618 PMCID: PMC6386415 DOI: 10.1371/journal.pgen.1007976] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 02/22/2019] [Accepted: 01/21/2019] [Indexed: 11/18/2022] Open
Abstract
Amino acids are among the earliest identified inducers of yeast-to-hyphal transitions in Candida albicans, an opportunistic fungal pathogen of humans. Here, we show that the morphogenic amino acids arginine, ornithine and proline are internalized and metabolized in mitochondria via a PUT1- and PUT2-dependent pathway that results in enhanced ATP production. Elevated ATP levels correlate with Ras1/cAMP/PKA pathway activation and Efg1-induced gene expression. The magnitude of amino acid-induced filamentation is linked to glucose availability; high levels of glucose repress mitochondrial function thereby dampening filamentation. Furthermore, arginine-induced morphogenesis occurs more rapidly and independently of Dur1,2-catalyzed urea degradation, indicating that mitochondrial-generated ATP, not CO2, is the primary morphogenic signal derived from arginine metabolism. The important role of the SPS-sensor of extracellular amino acids in morphogenesis is the consequence of induced amino acid permease gene expression, i.e., SPS-sensor activation enhances the capacity of cells to take up morphogenic amino acids, a requisite for their catabolism. C. albicans cells engulfed by murine macrophages filament, resulting in macrophage lysis. Phagocytosed put1-/- and put2-/- cells do not filament and exhibit reduced viability, consistent with a critical role of mitochondrial proline metabolism in virulence.
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Affiliation(s)
- Fitz Gerald S. Silao
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Meliza Ward
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Kicki Ryman
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Axel Wallström
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Björn Brindefalk
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Klas Udekwu
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Per O. Ljungdahl
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
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19
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Huang G, Huang Q, Wei Y, Wang Y, Du H. Multiple roles and diverse regulation of the Ras/cAMP/protein kinase A pathway in Candida albicans. Mol Microbiol 2018; 111:6-16. [PMID: 30299574 DOI: 10.1111/mmi.14148] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/01/2018] [Indexed: 01/15/2023]
Abstract
Candida albicans is a major fungal pathogen of humans, causing both superficial and life-threatening systemic infections in immunocompromised people. The conserved Ras/cAMP/PKA pathway plays a key role in regulating multiple traits important for the virulence of C. albicans such as cell growth, yeast-hyphal transition, white-opaque switching, sexual reproduction and biofilm development. Diverse external signals influence cell physiology by activating this signaling pathway. The key components of the Ras/cAMP/PKA pathway include two Ras GTPases (Ras1 and Ras2), an adenylyl cyclase (Cyr1, also known as Cdc35), two cyclic nucleotide phosphodiesterases (Pde1 and Pde2) and the catalytic (Tpk1 and Tpk2) and regulatory (Bcy1) subunits of PKA kinase. Activation of this pathway dramatically alters the gene expression profile via several transcription factors, leading to the activation of specific biological processes. Here, we review the progress made in the past two decades to elucidate the molecular mechanisms by which the Ras/cAMP/PKA pathway senses diverse environmental cues and controls specific cellular responses and its connection with other signaling pathways in C. albicans.
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Affiliation(s)
- Guanghua Huang
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, 200438, China.,State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qian Huang
- Department of Dermatology, Affiliated Hospital of Guizhou Medical University, Guiyang, 550025, China
| | - Yujia Wei
- Department of Dermatology, Affiliated Hospital of Guizhou Medical University, Guiyang, 550025, China
| | - Yue Wang
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore, 138673, Singapore.,Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 119228, Singapore
| | - Han Du
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, 200438, China.,Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
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20
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Chen C, Zeng G, Wang Y. G1 and S phase arrest in Candida albicans induces filamentous growth via distinct mechanisms. Mol Microbiol 2018; 110:191-203. [PMID: 30084240 DOI: 10.1111/mmi.14097] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 07/26/2018] [Accepted: 07/30/2018] [Indexed: 01/07/2023]
Abstract
Candida albicans is an opportunistic fungal pathogen. In immunocompromised individuals, it can cause bloodstream infections with high mortality rates. The ability to switch between yeast and hyphal morphologies is a critical virulence factor of C. albicans. In response to diverse environmental cues, several signaling pathways are activated resulting in filamentous growth. Interestingly, cell cycle arrest can also trigger filamentous growth although the pathways involved are not well-understood. Here, we demonstrate that the cAMP-PKA pathway is involved in the filamentous growth caused by G1 arrest due to the depletion of the G1 cyclin Cln3 and S phase arrest due to hydroxyurea treatment. The downstream mechanisms involved in filamentation are different between the two cell cycle arrest phenomena. Cln3-depleted cells require HGC1 and UME6 for filamentous growth, but hydroxyurea-induced filamentation does not. Also, the hyphal repressor Nrg1 is not involved in the suppression of Cln3-depletion and hydroxyurea-induced filamentous growth. The findings highlight the complexity of the signaling networks that control filamentous growth in which different mechanisms downstream of the cAMP-PKA pathway are activated based on the nature of the inducing signals.
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Affiliation(s)
- Cuilan Chen
- Institute of Molecular and Cell Biology, Agency for Science, Technology, and Research, Singapore
| | - Guisheng Zeng
- Institute of Molecular and Cell Biology, Agency for Science, Technology, and Research, Singapore
| | - Yue Wang
- Institute of Molecular and Cell Biology, Agency for Science, Technology, and Research, Singapore.,Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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21
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Ahmed R, Kodgire S, Santhakumari B, Patil R, Kulkarni M, Zore G. Serum responsive proteome reveals correlation between oxidative phosphorylation and morphogenesis in Candida albicans ATCC10231. J Proteomics 2018; 185:25-38. [PMID: 29959084 DOI: 10.1016/j.jprot.2018.06.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 06/05/2018] [Accepted: 06/18/2018] [Indexed: 12/17/2022]
Abstract
To understand the impact of fetal bovine serum (FBS) on metabolism and cellular architecture in addition to morphogenesis, we have identified FBS responsive proteome of Candida albicans. FBS induced 34% hyphae and 60% pseudohyphae in C. albicans at 30 °C while 98% hyphae at 37 °C. LC-MS/MS analysis revealed that 285 proteins modulated significantly in response to FBS at 30 °C and 37 °C. Out of which 152 were upregulated and 62 were downregulated at 30 °C while 18 were up and 53 were downregulated at 37 °C. Functional annotation suggests that FBS may inhibit glycolysis and fermentative pathway and enhance oxidative phosphorylation (OxPhos), TCA cycle, amino acid and fatty acid metabolism indicating a use of alternative energy source by C. albicans. OxPhos inhibition assay using sodium azide corroborated the correlation between inhibition of glycolysis and enhanced OxPhos with pseudohyphae formation. C. albicans induced hyphae in response to FBS irrespective of down regulation of Ras1,Asr1/Asr2, indicates the possible involvement of MAPK and cAMP-PKA independent pathway. The Cell wall of cells grown in presence of FBS at 30 °C was rich in mannan, Beta 1,3-glucan and chitin while membranes were rich in ergosterol compared to those grown at 37 °C. SIGNIFICANCE OF THE STUDY This is the first study suggesting a correlation between OxPhos and morphogenesis especially pseudohyphae formation in C. albicans. Our data also indicate that fetal bovine serum (FBS) induced morphogenesis is multifactorial and may involve MAPK and cAMP-PKA independent pathway. In addition to morphogenesis, our study provides an insight in to the modulation of metabolism and cellular architecture of C. albicans in response to FBS.
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Affiliation(s)
- Radfan Ahmed
- School of Life Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, MS, India
| | - Santosh Kodgire
- School of Life Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, MS, India
| | - B Santhakumari
- CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, MS, India.
| | - Rajendra Patil
- Department of Biotechnology, Savitribai Phule Pune University, Ganeshkhind, Pune 411007, MS, India.
| | - Mahesh Kulkarni
- CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, MS, India.
| | - Gajanan Zore
- School of Life Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, MS, India.
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22
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Ras hyperactivation versus overexpression: Lessons from Ras dynamics in Candida albicans. Sci Rep 2018; 8:5248. [PMID: 29588468 PMCID: PMC5869725 DOI: 10.1038/s41598-018-23187-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 03/06/2018] [Indexed: 12/25/2022] Open
Abstract
Ras signaling in response to environmental cues is critical for cellular morphogenesis in eukaryotes. This signaling is tightly regulated and its activation involves multiple players. Sometimes Ras signaling may be hyperactivated. In C. albicans, a human pathogenic fungus, we demonstrate that dynamics of hyperactivated Ras1 (Ras1G13V or Ras1 in Hsp90 deficient strains) can be reliably differentiated from that of normal Ras1 at (near) single molecule level using fluorescence correlation spectroscopy (FCS). Ras1 hyperactivation results in significantly slower dynamics due to actin polymerization. Activating actin polymerization by jasplakinolide can produce hyperactivated Ras1 dynamics. In a sterol-deficient hyperfilamentous GPI mutant of C. albicans too, Ras1 hyperactivation results from Hsp90 downregulation and causes actin polymerization. Hyperactivated Ras1 co-localizes with G-actin at the plasma membrane rather than with F-actin. Depolymerizing actin with cytochalasin D results in faster Ras1 dynamics in these and other strains that show Ras1 hyperactivation. Further, ergosterol does not influence Ras1 dynamics.
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23
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Yin T, Zhang Q, Wang J, Liu H, Wang C, Xu J, Jiang C. The cyclase-associated protein FgCap1 has both protein kinase A-dependent and -independent functions during deoxynivalenol production and plant infection in Fusarium graminearum. MOLECULAR PLANT PATHOLOGY 2018; 19:552-563. [PMID: 28142217 PMCID: PMC6638064 DOI: 10.1111/mpp.12540] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 01/21/2017] [Accepted: 01/23/2017] [Indexed: 05/25/2023]
Abstract
Fusarium graminearum is a causal agent of wheat scab and a producer of the trichothecene mycotoxin deoxynivalenol (DON). The expression of trichothecene biosynthesis (TRI) genes and DON production are mainly regulated by the cyclic adenosine monophosphate-protein kinase A (cAMP-PKA) pathway and two pathway-specific transcription factors (TRI6 and TRI10). Interestingly, deletion mutants of TRI6 show reduced expression of several components of cAMP signalling, including the FgCAP1 adenylate-binding protein gene that has not been functionally characterized in F. graminearum. In this study, we show that FgCap1 interacts with Fac1 adenylate cyclase and that deletion of FgCAP1 reduces the intracellular cAMP level and PKA activity. The Fgcap1 deletion mutant is defective in vegetative growth, conidiogenesis and plant infection. It also shows significantly reduced DON production and TRI gene expression, which can be suppressed by exogenous cAMP, indicating a PKA-dependent regulation of DON biosynthesis by FgCap1. The wild-type, but not tri6 mutant, shows increased levels of intracellular cAMP and FgCAP1 expression under DON-producing conditions. Furthermore, the promoter of FgCAP1 contains one putative Tri6-binding site that is important for its function during DON biosynthesis, but is dispensable for hyphal growth, conidiogenesis and pathogenesis. In addition, FgCap1 shows an actin-like localization to the cortical patches at the apical region of hyphal tips. Phosphorylation of FgCap1 at S353 was identified by phosphoproteomics analysis. The S353A mutation in FgCAP1 has no effect on its functions during vegetative growth, conidiation and DON production. However, expression of the FgCAP1S353A allele fails to complement the defects of the Fgcap1 mutant in plant infection, indicating the importance of the phosphorylation of FgCap1 at S353 during pathogenesis. Taken together, our results suggest that FgCAP1 is involved in the regulation of DON production via cAMP signalling and subjected to a feedback regulation by TRI6, but the phosphorylation of FgCap1 at S353 is probably unrelated to the cAMP-PKA pathway because the S353A mutation only affects plant infection.
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Affiliation(s)
- Tao Yin
- State Key Laboratory of Crop Stress Biology for Arid AreasNorthwest A&F UniversityYanglingShaanxi712100China
- Department of Botany and Plant PathologyPurdue UniversityWest LafayetteIN 47907USA
| | - Qiang Zhang
- State Key Laboratory of Crop Stress Biology for Arid AreasNorthwest A&F UniversityYanglingShaanxi712100China
| | - Jianhua Wang
- Department of Botany and Plant PathologyPurdue UniversityWest LafayetteIN 47907USA
- Institute for Agri‐food Standards and Testing TechnologyShanghai Academy of Agricultural SciencesShanghai201403China
| | - Huiquan Liu
- State Key Laboratory of Crop Stress Biology for Arid AreasNorthwest A&F UniversityYanglingShaanxi712100China
| | - Chenfang Wang
- State Key Laboratory of Crop Stress Biology for Arid AreasNorthwest A&F UniversityYanglingShaanxi712100China
| | - Jin‐Rong Xu
- State Key Laboratory of Crop Stress Biology for Arid AreasNorthwest A&F UniversityYanglingShaanxi712100China
- Department of Botany and Plant PathologyPurdue UniversityWest LafayetteIN 47907USA
| | - Cong Jiang
- State Key Laboratory of Crop Stress Biology for Arid AreasNorthwest A&F UniversityYanglingShaanxi712100China
- Department of Botany and Plant PathologyPurdue UniversityWest LafayetteIN 47907USA
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24
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Sac7 and Rho1 regulate the white-to-opaque switching in Candida albicans. Sci Rep 2018; 8:875. [PMID: 29343748 PMCID: PMC5772354 DOI: 10.1038/s41598-018-19246-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 12/19/2017] [Indexed: 11/17/2022] Open
Abstract
Candida albicans cells homozygous at the mating-type locus stochastically undergo the white-to-opaque switching to become mating-competent. This switching is regulated by a core circuit of transcription factors organized through interlocking feedback loops around the master regulator Wor1. Although a range of distinct environmental cues is known to induce the switching, the pathways linking the external stimuli to the central control mechanism remains largely unknown. By screening a C. albicans haploid gene-deletion library, we found that SAC7 encoding a GTPase-activating protein of Rho1 is required for the white-to-opaque switching. We demonstrate that Sac7 physically associates with Rho1-GTP and the constitutively active Rho1G18V mutant impairs the white-to-opaque switching while the inactive Rho1D124A mutant promotes it. Overexpressing WOR1 in both sac7Δ/Δ and rho1G18V cells suppresses the switching defect, indicating that the Sac7/Rho1 module acts upstream of Wor1. Furthermore, we provide evidence that Sac7/Rho1 functions in a pathway independent of the Ras/cAMP pathway which has previously been positioned upstream of Wor1. Taken together, we have discovered new regulators and a signaling pathway that regulate the white-to-opaque switching in the most prevalent human fungal pathogen C. albicans.
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25
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Glory A, van Oostende CT, Geitmann A, Bachewich C. Depletion of the mitotic kinase Cdc5p in Candida albicans results in the formation of elongated buds that switch to the hyphal fate over time in a Ume6p and Hgc1p-dependent manner. Fungal Genet Biol 2017; 107:51-66. [DOI: 10.1016/j.fgb.2017.08.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 07/27/2017] [Accepted: 08/08/2017] [Indexed: 10/19/2022]
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26
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Parrino SM, Si H, Naseem S, Groudan K, Gardin J, Konopka JB. cAMP-independent signal pathways stimulate hyphal morphogenesis in Candida albicans. Mol Microbiol 2016; 103:764-779. [PMID: 27888610 DOI: 10.1111/mmi.13588] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/22/2016] [Indexed: 11/29/2022]
Abstract
The fungal pathogen Candida albicans can transition from budding to hyphal growth, which promotes biofilm formation and invasive growth into tissues. Stimulation of adenylyl cyclase to form cAMP induces hyphal morphogenesis. The failure of cells lacking adenylyl cyclase (cyr1Δ) to form hyphae has suggested that cAMP signaling is essential for hyphal growth. However, cyr1Δ mutants also grow slowly and have defects in morphogenesis, making it unclear whether hyphal inducers must stimulate cAMP, or if normal basal levels of cAMP are required to maintain cellular health needed for hyphal growth. Interestingly, supplementation of cyr1Δ cells with low levels of cAMP enabled them to form hyphae in response to the inducer N-acetylglucosamine (GlcNAc), suggesting that a basal level of cAMP is sufficient for stimulation. Furthermore, we isolated faster-growing cyr1Δ pseudorevertant strains that can be induced to form hyphae even though they lack cAMP. The pseudorevertant strains were not induced by CO2 , consistent with reports that CO2 directly stimulates adenylyl cyclase. Mutational analysis showed that induction of hyphae in a pseudorevertant strain was independent of RAS1, but was dependent on the EFG1 transcription factor that acts downstream of protein kinase A. Thus, cAMP-independent signals contribute to the induction of hyphal responses.
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Affiliation(s)
- Salvatore M Parrino
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA.,Graduate Program in Molecular and Cellular Biology, Stony Brook University, Stony Brook, NY, USA
| | - Haoyu Si
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA
| | - Shamoon Naseem
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA
| | - Kevin Groudan
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA
| | - Justin Gardin
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA.,Graduate Program in Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA
| | - James B Konopka
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA
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27
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Noble SM, Gianetti BA, Witchley JN. Candida albicans cell-type switching and functional plasticity in the mammalian host. Nat Rev Microbiol 2016; 15:96-108. [PMID: 27867199 DOI: 10.1038/nrmicro.2016.157] [Citation(s) in RCA: 331] [Impact Index Per Article: 41.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Candida albicans is a ubiquitous commensal of the mammalian microbiome and the most prevalent fungal pathogen of humans. A cell-type transition between yeast and hyphal morphologies in C. albicans was thought to underlie much of the variation in virulence observed in different host tissues. However, novel yeast-like cell morphotypes, including opaque(a/α), grey and gastrointestinally induced transition (GUT) cell types, were recently reported that exhibit marked differences in vitro and in animal models of commensalism and disease. In this Review, we explore the characteristics of the classic cell types - yeast, hyphae, pseudohyphae and chlamydospores - as well as the newly identified yeast-like morphotypes. We highlight emerging knowledge about the associations of these different morphotypes with different host niches and virulence potential, as well as the environmental cues and signalling pathways that are involved in the morphological transitions.
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Affiliation(s)
- Suzanne M Noble
- Department of Microbiology and Immunology, University of California San Francisco (UCSF) School of Medicine.,Infectious Diseases Division, Department of Medicine, University of California San Francisco (UCSF) School of Medicine, San Francisco, California 94143, USA
| | - Brittany A Gianetti
- Department of Microbiology and Immunology, University of California San Francisco (UCSF) School of Medicine
| | - Jessica N Witchley
- Department of Microbiology and Immunology, University of California San Francisco (UCSF) School of Medicine
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28
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Signaling through Lrg1, Rho1 and Pkc1 Governs Candida albicans Morphogenesis in Response to Diverse Cues. PLoS Genet 2016; 12:e1006405. [PMID: 27788136 PMCID: PMC5082861 DOI: 10.1371/journal.pgen.1006405] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 10/04/2016] [Indexed: 12/22/2022] Open
Abstract
The capacity to transition between distinct morphological forms is a key virulence trait for diverse fungal pathogens. A poignant example of a leading opportunistic fungal pathogen of humans for which an environmentally responsive developmental program underpins virulence is Candida albicans. C. albicans mutants that are defective in the transition between yeast and filamentous forms typically have reduced virulence. Although many positive regulators of C. albicans filamentation have been defined, there are fewer negative regulators that have been implicated in repression of filamentation in the absence of inducing cues. To discover novel negative regulators of filamentation, we screened a collection of 1,248 C. albicans homozygous transposon insertion mutants to identify those that were filamentous in the absence of inducing cues. We identified the Rho1 GAP Lrg1, which represses filamentous growth by stimulating Rho1 GTPase activity and converting Rho1 to its inactive, GDP-bound form. Deletion of LRG1 or introduction of a RHO1 mutation that locks Rho1 in constitutively active, GTP-bound state, leads to filamentation in the absence of inducing cues. Deletion of the Rho1 downstream effector PKC1 results in defective filamentation in response to diverse host-relevant inducing cues, including serum. We further established that Pkc1 is not required to sense filament-inducing cues, but its kinase activity is critical for the initiation of filamentous growth. Our genetic analyses revealed that Pkc1 regulates filamentation independent of the canonical MAP kinase cascade. Further, although Ras1 activation is not impaired in a pkc1Δ/pkc1Δ mutant, adenylyl cyclase activity is reduced, consistent with a model in which Pkc1 functions in parallel with Ras1 in regulating Cyr1 activation. Thus, our findings delineate a signaling pathway comprised of Lrg1, Rho1 and Pkc1 with a core role in C. albicans morphogenesis, and illuminate functional relationships that govern activation of a central transducer of signals that control environmental response and virulence programs.
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29
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Candidalysin is a fungal peptide toxin critical for mucosal infection. Nature 2016; 532:64-8. [PMID: 27027296 PMCID: PMC4851236 DOI: 10.1038/nature17625] [Citation(s) in RCA: 582] [Impact Index Per Article: 72.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 02/26/2016] [Indexed: 01/23/2023]
Abstract
Cytolytic proteins and peptide toxins are classical virulence factors of several bacterial pathogens which disrupt epithelial barrier function, damage cells and activate or modulate host immune responses. Such toxins have not been identified previously in human pathogenic fungi. Here we identify the first, to our knowledge, fungal cytolytic peptide toxin in the opportunistic pathogen Candida albicans. This secreted toxin directly damages epithelial membranes, triggers a danger response signalling pathway and activates epithelial immunity. Membrane permeabilization is enhanced by a positive charge at the carboxy terminus of the peptide, which triggers an inward current concomitant with calcium influx. C. albicans strains lacking this toxin do not activate or damage epithelial cells and are avirulent in animal models of mucosal infection. We propose the name 'Candidalysin' for this cytolytic peptide toxin; a newly identified, critical molecular determinant of epithelial damage and host recognition of the clinically important fungus, C. albicans.
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30
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Abstract
Morphogenesis in fungi is often induced by extracellular factors and executed by fungal genetic factors. Cell surface changes and alterations of the microenvironment often accompany morphogenetic changes in fungi. In this review, we will first discuss the general traits of yeast and hyphal morphotypes and how morphogenesis affects development and adaptation by fungi to their native niches, including host niches. Then we will focus on the molecular machinery responsible for the two most fundamental growth forms, yeast and hyphae. Last, we will describe how fungi incorporate exogenous environmental and host signals together with genetic factors to determine their morphotype and how morphogenesis, in turn, shapes the fungal microenvironment.
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Affiliation(s)
- Xiaorong Lin
- Department of Biology, Texas A&M University, College Station, Texas 77843-3258
| | - J Andrew Alspaugh
- Department of Medicine, Division of Infectious Diseases, Duke University Medical Center, Durham, North Carolina 27710
| | - Haoping Liu
- Department of Biological Chemistry, University of California, Irvine, California 92697
| | - Steven Harris
- Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, Nebraska 68588
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31
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Lu Y, Su C, Liu H. Candida albicans hyphal initiation and elongation. Trends Microbiol 2014; 22:707-14. [PMID: 25262420 DOI: 10.1016/j.tim.2014.09.001] [Citation(s) in RCA: 141] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 08/28/2014] [Accepted: 09/03/2014] [Indexed: 01/01/2023]
Abstract
The fungus Candida albicans is a benign member of the mucosal microbiota, but can cause mucosal infections and life-threatening disseminated invasive infections in susceptible individuals. The ability to switch between yeast, pseudohyphal, and hyphal growth forms (polymorphism) is one of the most investigated virulence attributes of C. albicans. Recent studies suggest that hyphal development in C. albicans requires two temporally linked regulations for initiation and maintenance of the hyphal transcriptional program. Hyphal initiation requires a rapid but temporary disappearance of the Nrg1 transcriptional repressor of hyphal morphogenesis. Hyphal maintenance requires active sensing of the surrounding environment, leading to exclusion of Nrg1 binding to promoters of hypha-specific genes or reduced NRG1 expression. We discuss recent advances in understanding the complex transcriptional regulation of hyphal gene expression. These provide molecular mechanisms underpinning the phenotypic plasticity of C. albicans polymorphism.
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Affiliation(s)
- Yang Lu
- Department of Biological Chemistry, University of California, Irvine, CA 92697, USA
| | - Chang Su
- Department of Biological Chemistry, University of California, Irvine, CA 92697, USA
| | - Haoping Liu
- Department of Biological Chemistry, University of California, Irvine, CA 92697, USA.
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32
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Ono S. The role of cyclase-associated protein in regulating actin filament dynamics - more than a monomer-sequestration factor. J Cell Sci 2014; 126:3249-58. [PMID: 23908377 DOI: 10.1242/jcs.128231] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Dynamic reorganization of the actin cytoskeleton is fundamental to a number of cell biological events. A variety of actin-regulatory proteins modulate polymerization and depolymerization of actin and contribute to actin cytoskeletal reorganization. Cyclase-associated protein (CAP) is a conserved actin-monomer-binding protein that has been studied for over 20 years. Early studies have shown that CAP sequesters actin monomers; recent studies, however, have revealed more active roles of CAP in actin filament dynamics. CAP enhances the recharging of actin monomers with ATP antagonistically to ADF/cofilin, and also promotes the severing of actin filaments in cooperation with ADF/cofilin. Self-oligomerization and binding to other proteins regulate activities and localization of CAP. CAP has crucial roles in cell signaling, development, vesicle trafficking, cell migration and muscle sarcomere assembly. This Commentary discusses the recent advances in our understanding of the functions of CAP and its implications as an important regulator of actin cytoskeletal dynamics, which are involved in various cellular activities.
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Affiliation(s)
- Shoichiro Ono
- Department of Pathology and Department of Cell Biology, Emory University, Atlanta, GA 30322, USA.
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33
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Abstract
For centuries yeast species have been popular hosts for classical biotechnology processes, such as baking, brewing, and wine making, and more recently for recombinant proteins production, thanks to the advantages of unicellular organisms (i.e., ease of genetic manipulation and rapid growth) together with the ability to perform eukaryotic posttranslational modifications. Moreover, yeast cells have been used for few decades as a tool for identifying the genes and pathways involved in basic cellular processes such as the cell cycle, aging, and stress response. In the budding yeast S. cerevisiae the Ras/cAMP/PKA pathway is directly involved in the regulation of metabolism, cell growth, stress resistance, and proliferation in response to the availability of nutrients and in the adaptation to glucose, controlling cytosolic cAMP levels and consequently the cAMP-dependent protein kinase (PKA) activity. Moreover, Ras signalling has been identified in several pathogenic yeasts as a key controller for virulence, due to its involvement in yeast morphogenesis. Nowadays, yeasts are still useful for Ras-like proteins investigation, both as model organisms and as a test tube to study variants of heterologous Ras-like proteins.
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Affiliation(s)
- Renata Tisi
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan, Italy
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34
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Crabbé A, Nielsen-Preiss SM, Woolley CM, Barrila J, Buchanan K, McCracken J, Inglis DO, Searles SC, Nelman-Gonzalez MA, Ott CM, Wilson JW, Pierson DL, Stefanyshyn-Piper HM, Hyman LE, Nickerson CA. Spaceflight enhances cell aggregation and random budding in Candida albicans. PLoS One 2013; 8:e80677. [PMID: 24324620 PMCID: PMC3851762 DOI: 10.1371/journal.pone.0080677] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 10/07/2013] [Indexed: 12/24/2022] Open
Abstract
This study presents the first global transcriptional profiling and phenotypic characterization of the major human opportunistic fungal pathogen, Candida albicans, grown in spaceflight conditions. Microarray analysis revealed that C. albicans subjected to short-term spaceflight culture differentially regulated 452 genes compared to synchronous ground controls, which represented 8.3% of the analyzed ORFs. Spaceflight-cultured C. albicans–induced genes involved in cell aggregation (similar to flocculation), which was validated by microscopic and flow cytometry analysis. We also observed enhanced random budding of spaceflight-cultured cells as opposed to bipolar budding patterns for ground samples, in accordance with the gene expression data. Furthermore, genes involved in antifungal agent and stress resistance were differentially regulated in spaceflight, including induction of ABC transporters and members of the major facilitator family, downregulation of ergosterol-encoding genes, and upregulation of genes involved in oxidative stress resistance. Finally, downregulation of genes involved in actin cytoskeleton was observed. Interestingly, the transcriptional regulator Cap1 and over 30% of the Cap1 regulon was differentially expressed in spaceflight-cultured C. albicans. A potential role for Cap1 in the spaceflight response of C. albicans is suggested, as this regulator is involved in random budding, cell aggregation, and oxidative stress resistance; all related to observed spaceflight-associated changes of C. albicans. While culture of C. albicans in microgravity potentiates a global change in gene expression that could induce a virulence-related phenotype, no increased virulence in a murine intraperitoneal (i.p.) infection model was observed under the conditions of this study. Collectively, our data represent an important basis for the assessment of the risk that commensal flora could play during human spaceflight missions. Furthermore, since the low fluid-shear environment of microgravity is relevant to physical forces encountered by pathogens during the infection process, insights gained from this study could identify novel infectious disease mechanisms, with downstream benefits for the general public.
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Affiliation(s)
- Aurélie Crabbé
- Center for Infectious Diseases and Vaccinology, The Biodesign Institute, Arizona State University, Tempe, Arizona, United States of America
| | - Sheila M. Nielsen-Preiss
- Department of Immunology and Infectious Disease, Montana State University, Bozeman, Montanta, United States of America
| | - Christine M. Woolley
- Department of Immunology and Infectious Disease, Montana State University, Bozeman, Montanta, United States of America
| | - Jennifer Barrila
- Center for Infectious Diseases and Vaccinology, The Biodesign Institute, Arizona State University, Tempe, Arizona, United States of America
| | - Kent Buchanan
- Department of Biology, Oklahoma City University, Oklahoma City, Oklahoma, United States of America
- Department of Microbiology and Immunology, Program in Molecular Pathogenesis and Immunity, Tulane University Health Sciences Center, New Orleans, Louisiana, United States of America
| | - James McCracken
- Department of Microbiology and Immunology, Program in Molecular Pathogenesis and Immunity, Tulane University Health Sciences Center, New Orleans, Louisiana, United States of America
- Diabetes and Obesity Center, University of Louisville, Louisville, Kentucky, United States of America
| | - Diane O. Inglis
- Department of Genetics, Stanford University Medical School, Stanford, California, United States of America
| | - Stephen C. Searles
- Department of Immunology and Infectious Disease, Montana State University, Bozeman, Montanta, United States of America
| | | | - C. Mark Ott
- Biomedical Research and Environmental Sciences Division, NASA Johnson Space Center, Houston, Texas, United States of America
| | - James W. Wilson
- Center for Infectious Diseases and Vaccinology, The Biodesign Institute, Arizona State University, Tempe, Arizona, United States of America
- Department of Microbiology and Immunology, Program in Molecular Pathogenesis and Immunity, Tulane University Health Sciences Center, New Orleans, Louisiana, United States of America
- Department of Biology, Villanova University, Villanova, Pennsylvania, United States of America
| | - Duane L. Pierson
- Biomedical Research and Environmental Sciences Division, NASA Johnson Space Center, Houston, Texas, United States of America
| | | | - Linda E. Hyman
- Department of Immunology and Infectious Disease, Montana State University, Bozeman, Montanta, United States of America
- Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Cheryl A. Nickerson
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
- Center for Infectious Diseases and Vaccinology, The Biodesign Institute, Arizona State University, Tempe, Arizona, United States of America
- Department of Microbiology and Immunology, Program in Molecular Pathogenesis and Immunity, Tulane University Health Sciences Center, New Orleans, Louisiana, United States of America
- * E-mail:
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The MARVEL domain protein Nce102 regulates actin organization and invasive growth of Candida albicans. mBio 2013; 4:e00723-13. [PMID: 24281718 PMCID: PMC3870249 DOI: 10.1128/mbio.00723-13] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Invasive growth of the fungal pathogen Candida albicans into tissues promotes disseminated infections in humans. The plasma membrane is essential for pathogenesis because this important barrier mediates morphogenesis and invasive growth, as well as secretion of virulence factors, cell wall synthesis, nutrient import, and other processes. Previous studies showed that the Sur7 tetraspan protein that localizes to MCC (membrane compartment occupied by Can1)/eisosome subdomains of the plasma membrane regulates a broad range of key functions, including cell wall synthesis, morphogenesis, and resistance to copper. Therefore, a distinct tetraspan protein found in MCC/eisosomes, Nce102, was investigated. Nce102 belongs to the MARVEL domain protein family, which is implicated in regulating membrane structure and function. Deletion of NCE102 did not cause the broad defects seen in sur7Δ cells. Instead, the nce102Δ mutant displayed a unique phenotype in that it was defective in forming hyphae and invading low concentrations of agar but could invade well in higher agar concentrations. This phenotype was likely due to a defect in actin organization that was observed by phalloidin staining. In support of this, the invasive growth defect of a bni1Δ mutant that mislocalizes actin due to lack of the Bni1 formin was also reversed at high agar concentrations. This suggests that a denser matrix provides a signal that compensates for the actin defects. The nce102Δ mutant displayed decreased virulence and formed abnormal hyphae in mice. These studies identify novel ways that Nce102 and the physical environment surrounding C. albicans regulate morphogenesis and pathogenesis. The plasma membrane promotes virulence of the human fungal pathogen Candida albicans by acting as a protective barrier around the cell and mediating dynamic activities, such as morphogenesis, cell wall synthesis, secretion of virulence factors, and nutrient uptake. To better understand how the plasma membrane contributes to virulence, we analyzed a set of eight genes encoding MARVEL family proteins that are predicted to function in membrane organization. Interestingly, deletion of one gene, NCE102, caused a strong defect in formation of invasive hyphal growth in vitro and decreased virulence in mice. The nce102Δ mutant cells showed defects in actin organization that underlie the morphogenesis defect, since mutation of a known regulator of actin organization caused a similar defect. These studies identify a novel way in which the plasma membrane regulates the actin cytoskeleton and contributes to pathogenesis.
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Wang Y. Fungal adenylyl cyclase acts as a signal sensor and integrator and plays a central role in interaction with bacteria. PLoS Pathog 2013; 9:e1003612. [PMID: 24130478 PMCID: PMC3795026 DOI: 10.1371/journal.ppat.1003612] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Affiliation(s)
- Yue Wang
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
- * E-mail:
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Candida albicans Czf1 and Efg1 coordinate the response to farnesol during quorum sensing, white-opaque thermal dimorphism, and cell death. EUKARYOTIC CELL 2013; 12:1281-92. [PMID: 23873867 DOI: 10.1128/ec.00311-12] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Quorum sensing by farnesol in Candida albicans inhibits filamentation and may be directly related to its ability to cause both mucosal and systemic diseases. The Ras1-cyclic AMP signaling pathway is a target for farnesol inhibition. However, a clear understanding of the downstream effectors of the morphological farnesol response has yet to be unraveled. To address this issue, we screened a library for mutants that fail to respond to farnesol. Six mutants were identified, and the czf1Δ/czf1Δ mutant was selected for further characterization. Czf1 is a transcription factor that regulates filamentation in embedded agar and also white-to-opaque switching. We found that Czf1 is required for filament inhibition by farnesol under at least three distinct environmental conditions: on agar surfaces, in liquid medium, and when embedded in a semisolid agar matrix. Since Efg1 is a transcription factor of the Ras1-cyclic AMP signaling pathway that interacts with and regulates Czf1, an efg1Δ/efg1Δ czf1Δ/czf1Δ mutant was tested for filament inhibition by farnesol. It exhibited an opaque-cell-like temperature-dependent morphology, and it was killed by low farnesol levels that are sublethal to wild-type cells and both efg1Δ/efg1Δ and czf1Δ/czf1Δ single mutants. These results highlight a new role for Czf1 as a downstream effector of the morphological response to farnesol, and along with Efg1, Czf1 is involved in the control of farnesol-mediated cell death in C. albicans.
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38
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Heintz-Buschart A, Eickhoff H, Hohn E, Bilitewski U. Identification of inhibitors of yeast-to-hyphae transition in Candida albicans by a reporter screening assay. J Biotechnol 2013; 164:137-42. [DOI: 10.1016/j.jbiotec.2012.12.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Revised: 11/15/2012] [Accepted: 12/10/2012] [Indexed: 10/27/2022]
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39
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Kuo ZY, Chuang YJ, Chao CC, Liu FC, Lan CY, Chen BS. Identification of infection- and defense-related genes via a dynamic host-pathogen interaction network using a Candida albicans-zebrafish infection model. J Innate Immun 2013; 5:137-52. [PMID: 23406717 DOI: 10.1159/000347104] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Accepted: 01/15/2013] [Indexed: 01/10/2023] Open
Abstract
Candida albicans infections and candidiasis are difficult to treat and create very serious therapeutic challenges. In this study, based on interactive time profile microarray data of C. albicans and zebrafish during infection, the infection-related protein-protein interaction (PPI) networks of the two species and the intercellular PPI network between host and pathogen were simultaneously constructed by a dynamic interaction model, modeled as an integrated network consisting of intercellular invasion and cellular defense processes during infection. The signal transduction pathways in regulating morphogenesis and hyphal growth of C. albicans were further investigated based on significant interactions found in the intercellular PPI network. Two cellular networks were also developed corresponding to the different infection stages (adhesion and invasion), and then compared with each other to identify proteins from which we can gain more insight into the pathogenic role of hyphal development in the C. albicans infection process. Important defense-related proteins in zebrafish were predicted using the same approach. The hyphal growth PPI network, zebrafish PPI network and host-pathogen intercellular PPI network were combined to form an integrated infectious PPI network that helps us understand the systematic mechanisms underlying the pathogenicity of C. albicans and the immune response of the host, and may help improve medical therapies and facilitate the development of new antifungal drugs.
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Affiliation(s)
- Zong-Yu Kuo
- Laboratory of Control and Systems Biology, Department of Electrical Engineering, National Tsing Hua University, Hsinchu, Taiwan, ROC
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Gancedo JM. Biological roles of cAMP: variations on a theme in the different kingdoms of life. Biol Rev Camb Philos Soc 2013; 88:645-68. [PMID: 23356492 DOI: 10.1111/brv.12020] [Citation(s) in RCA: 119] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 12/19/2012] [Accepted: 12/20/2012] [Indexed: 12/18/2022]
Abstract
Cyclic AMP (cAMP) plays a key regulatory role in most types of cells; however, the pathways controlled by cAMP may present important differences between organisms and between tissues within a specific organism. Changes in cAMP levels are caused by multiple triggers, most affecting adenylyl cyclases, the enzymes that synthesize cAMP. Adenylyl cyclases form a large and diverse family including soluble forms and others with one or more transmembrane domains. Regulatory mechanisms for the soluble adenylyl cyclases involve either interaction with diverse proteins, as happens in Escherichia coli or yeasts, or with calcium or bicarbonate ions, as occurs in mammalian cells. The transmembrane cyclases can be regulated by a variety of proteins, among which the α subunit and the βγ complex from G proteins coupled to membrane receptors are prominent. cAMP levels also are controlled by the activity of phosphodiesterases, enzymes that hydrolyze cAMP. Phosphodiesterases can be regulated by cAMP, cGMP or calcium-calmodulin or by phosphorylation by different protein kinases. Regulation through cAMP depends on its binding to diverse proteins, its proximal targets, this in turn causing changes in a variety of distal targets. Specifically, binding of cAMP to regulatory subunits of cAMP-dependent protein kinases (PKAs) affects the activity of substrates of PKA, binding to exchange proteins directly activated by cAMP (Epac) regulates small GTPases, binding to transcription factors such as the cAMP receptor protein (CRP) or the virulence factor regulator (Vfr) modifies the rate of transcription of certain genes, while cAMP binding to ion channels modulates their activity directly. Further studies on cAMP signalling will have important implications, not only for advancing fundamental knowledge but also for identifying targets for the development of new therapeutic agents.
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Affiliation(s)
- Juana M Gancedo
- Department of Metabolism and Cell Signalling, Instituto de Investigaciones Biomédicas Alberto Sols CSIC-UAM, Madrid 28029, Spain.
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Rsr1 focuses Cdc42 activity at hyphal tips and promotes maintenance of hyphal development in Candida albicans. EUKARYOTIC CELL 2012; 12:482-95. [PMID: 23223038 DOI: 10.1128/ec.00294-12] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The extremely elongated morphology of fungal hyphae is dependent on the cell's ability to assemble and maintain polarized growth machinery over multiple cell cycles. The different morphologies of the fungus Candida albicans make it an excellent model organism in which to study the spatiotemporal requirements for constitutive polarized growth and the generation of different cell shapes. In C. albicans, deletion of the landmark protein Rsr1 causes defects in morphogenesis that are not predicted from study of the orthologous protein in the related yeast Saccharomyces cerevisiae, thus suggesting that Rsr1 has expanded functions during polarized growth in C. albicans. Here, we show that Rsr1 activity localizes to hyphal tips by the differential localization of the Rsr1 GTPase-activating protein (GAP), Bud2, and guanine nucleotide exchange factor (GEF), Bud5. In addition, we find that Rsr1 is needed to maintain the focused localization of hyphal polarity structures and proteins, including Bem1, a marker of the active GTP-bound form of the Rho GTPase, Cdc42. Further, our results indicate that tip-localized Cdc42 clusters are associated with the cell's ability to express a hyphal transcriptional program and that the ability to generate a focused Cdc42 cluster in early hyphae (germ tubes) is needed to maintain hyphal morphogenesis over time. We propose that in C. albicans, Rsr1 "fine-tunes" the distribution of Cdc42 activity and that self-organizing (Rsr1-independent) mechanisms of polarized growth are not sufficient to generate narrow cell shapes or to provide feedback to the transcriptional program during hyphal morphogenesis.
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Su C, Lu Y, Liu H. Reduced TOR signaling sustains hyphal development in Candida albicans by lowering Hog1 basal activity. Mol Biol Cell 2012; 24:385-97. [PMID: 23171549 PMCID: PMC3564525 DOI: 10.1091/mbc.e12-06-0477] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Many signaling pathways important for hyphal development have been identified, but how Candida albicans coordinates information from these signaling pathways during hyphal development remains a major question. It is shown that reduced Tor1 signaling lowers the basal activity of the Hog1 MAP kinase to sustain hyphal elongation. Candida albicans is able to undergo reversible morphological changes between yeast and hyphal forms in response to environmental cues. This morphological plasticity is essential for its pathogenesis. Hyphal development requires two temporally linked changes in promoter chromatin, which is sequentially regulated by temporarily clearing the transcription inhibitor Nrg1 upon activation of cAMP/protein kinase A and promoter recruitment of the histone deacetylase Hda1 under reduced target of rapamycin (Tor1) signaling. The GATA family transcription factor Brg1 recruits Hda1 to promoters for sustained hyphal development, and BRG1 expression is a readout of reduced Tor1 signaling. How Tor1 regulates BRG1 expression is not clear. Using a forward genetic screen for mutants that can sustain hyphal elongation in rich media, we found hog1, ssk2, and pbs2 mutants of the HOG mitogen-activated protein kinase pathway to express BRG1 irrespective of rapamycin. Furthermore, rapamycin lowers the basal activity of Hog1 through the functions of the two Hog1 tyrosine phosphatases Ptp2 and Ptp3. Active Hog1 represses the expression of BRG1 via the transcriptional repressor Sko1 as Sko1 disassociates from the promoter of BRG1 in the hog1 mutant or in rapamycin. Our data suggest that reduced Tor1 signaling lowers Hog1 basal activity via Hog1 phosphatases to activate BRG1 expression for hyphal elongation.
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Affiliation(s)
- Chang Su
- Department of Biological Chemistry, University of California, Irvine, Irvine, CA 92697, USA
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Zhou X, Zhang H, Li G, Shaw B, Xu JR. The Cyclase-associated protein Cap1 is important for proper regulation of infection-related morphogenesis in Magnaporthe oryzae. PLoS Pathog 2012; 8:e1002911. [PMID: 22969430 PMCID: PMC3435248 DOI: 10.1371/journal.ppat.1002911] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 08/02/2012] [Indexed: 12/03/2022] Open
Abstract
Surface recognition and penetration are critical steps in the infection cycle of many plant pathogenic fungi. In Magnaporthe oryzae, cAMP signaling is involved in surface recognition and pathogenesis. Deletion of the MAC1 adenylate cyclase gene affected appressorium formation and plant infection. In this study, we used the affinity purification approach to identify proteins that are associated with Mac1 in vivo. One of the Mac1-interacting proteins is the adenylate cyclase-associated protein named Cap1. CAP genes are well-conserved in phytopathogenic fungi but none of them have been functionally characterized. Deletion of CAP1 blocked the effects of a dominant RAS2 allele and resulted in defects in invasive growth and a reduced intracellular cAMP level. The Δcap1 mutant was defective in germ tube growth, appressorium formation, and formation of typical blast lesions. Cap1-GFP had an actin-like localization pattern, localizing to the apical regions in vegetative hyphae, at the periphery of developing appressoria, and in circular structures at the base of mature appressoria. Interestingly, Cap1, similar to LifeAct, did not localize to the apical regions in invasive hyphae, suggesting that the apical actin cytoskeleton differs between vegetative and invasive hyphae. Domain deletion analysis indicated that the proline-rich region P2 but not the actin-binding domain (AB) of Cap1 was responsible for its subcellular localization. Nevertheless, the AB domain of Cap1 must be important for its function because CAP1ΔAB only partially rescued the Δcap1 mutant. Furthermore, exogenous cAMP induced the formation of appressorium-like structures in non-germinated conidia in CAP1ΔAB transformants. This novel observation suggested that AB domain deletion may result in overstimulation of appressorium formation by cAMP treatment. Overall, our results indicated that CAP1 is important for the activation of adenylate cyclase, appressorium morphogenesis, and plant infection in M. oryzae. CAP1 may also play a role in feedback inhibition of Ras2 signaling when Pmk1 is activated. In Magnaporthe oryzae, cAMP signaling is known to play an important role in surface recognition and plant penetration. The Mac1 adenylate cyclase is essential for plant infection. To better understand Mac1 activation mechanisms, in this study we used the affinity purification approach to identify proteins that are associated with Mac1 in vivo. One of the Mac1-interacting protein is the adenylate cyclase associated protein (CAP) encoded by the CAP1 gene. Results from our study indicated that Cap1 is important for Mac1 activation and plant infection in M. oryzae. The Δcap1 mutant was defective in germ tube growth and appressorium formation and failed to cause typical blast lesions. Like LifeAct, Cap1 localized to apical patches in vegetative hyphae but not in invasive hyphae. The P2 proline-rich region was important for Cap1 localization but the actin-binding domain played a role in feedback inhibition of Ras signaling. To our knowledge, functional characterization of CAP genes has not been reported in filamentous fungi. Our results indicate that CAP1 is important for regulating adenylate cyclase activities, appressorium morphogenesis, and plant infection. Further characterization of CAP1 will be important to better understand the interaction between cAMP signaling and the PMK1 pathway in M. oryzae.
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Affiliation(s)
- Xiaoying Zhou
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America
| | - Haifeng Zhang
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America
| | - Guotian Li
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America
- Purdue-NWAFU Joint Research Center, College of Plant Protection, Northwest A&F University, Yangling, Shanxi, China
| | - Brian Shaw
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas, United States of America
| | - Jin-Rong Xu
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America
- Purdue-NWAFU Joint Research Center, College of Plant Protection, Northwest A&F University, Yangling, Shanxi, China
- * E-mail:
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Hu K, Li W, Wang H, Chen K, Wang Y, Sang J. Shp1, a regulator of protein phosphatase 1 Glc7, has important roles in cell morphogenesis, cell cycle progression and DNA damage response in Candida albicans. Fungal Genet Biol 2012; 49:433-42. [PMID: 22542681 DOI: 10.1016/j.fgb.2012.04.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Revised: 04/04/2012] [Accepted: 04/14/2012] [Indexed: 01/15/2023]
Abstract
In yeast, the type 1 protein phosphatase (PP1) catalytic subunit Glc7 is involved in the regulation of multiple cellular processes and thought to achieve specificity through association with different regulatory subunits. Here, we report that the Glc7 regulator Shp1 plays important roles in cell morphogenesis, cell cycle progression and DNA damage response in Candida albicans. SHP1 deletion caused the formation of rod-shaped yeast cells with slow growth. Flow cytometry analysis revealed that shp1Δ cells showed a prolonged G(2)/M phase, which was rescued by deleting the spindle-checkpoint gene MAD2. Furthermore, shp1Δ cells were hypersensitive to heat and genotoxic stresses. Interestingly, depletion of Glc7 caused defects similar to the shp1Δ mutant such as arrest at G(2)/M transition; and the GLC7/glc7Δ heterozygous mutant exhibited increased sensitivity to genotoxic stresses, consistent with the recent finding that Saccharomyces cerevisiae Glc7 has a role in DNA damage response. We also show that Shp1 is required for the nuclear accumulation of Glc7, suggesting that Shp1 executes its cellular function partly by regulating Glc7 localization.
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Affiliation(s)
- Kangdi Hu
- Key Laboratory of Cell Proliferation and Regulation Biology, Ministry of Education, College of Life Sciences, Beijing Normal University, Beijing 100875, People's Republic of China
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45
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Bharucha N, Chabrier-Roselló Y, Xu T, Johnson C, Sobczynski S, Song Q, Dobry CJ, Eckwahl MJ, Anderson CP, Benjamin AJ, Kumar A, Krysan DJ. A large-scale complex haploinsufficiency-based genetic interaction screen in Candida albicans: analysis of the RAM network during morphogenesis. PLoS Genet 2011; 7:e1002058. [PMID: 22103005 PMCID: PMC3084211 DOI: 10.1371/journal.pgen.1002058] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The morphogenetic transition between yeast and filamentous forms of the human
fungal pathogen Candida albicans is regulated by a variety of
signaling pathways. How these pathways interact to orchestrate morphogenesis,
however, has not been as well characterized. To address this question and to
identify genes that interact with the Regulation of Ace2 and Morphogenesis (RAM)
pathway during filamentation, we report the first large-scale genetic
interaction screen in C. albicans. Our strategy for this screen
was based on the concept of complex haploinsufficiency (CHI). A heterozygous
mutant of CBK1
(cbk1Δ/CBK1), a key RAM pathway
protein kinase, was subjected to transposon-mediated, insertional mutagenesis.
The resulting double heterozygous mutants (6,528 independent strains) were
screened for decreased filamentation on Spider Medium (SM). From the 441 mutants
showing altered filamentation, 139 transposon insertion sites were sequenced,
yielding 41 unique CBK1-interacting genes. This gene set was
enriched in transcriptional targets of Ace2 and, strikingly, the cAMP-dependent
protein kinase A (PKA) pathway, suggesting an interaction between these two
pathways. Further analysis indicates that the RAM and PKA pathways co-regulate a
common set of genes during morphogenesis and that hyper-activation of the PKA
pathway may compensate for loss of RAM pathway function. Our data also indicate
that the PKA–regulated transcription factor Efg1 primarily localizes to
yeast phase cells while the RAM–pathway regulated transcription factor
Ace2 localizes to daughter nuclei of filamentous cells, suggesting that Efg1 and
Ace2 regulate a common set of genes at separate stages of morphogenesis. Taken
together, our observations indicate that CHI–based screening is a useful
approach to genetic interaction analysis in C. albicans and
support a model in which these two pathways regulate a common set of genes at
different stages of filamentation. Candida albicans is the most common cause of fungal infections
in humans. As a diploid yeast without a classical sexual cycle, many genetic
approaches developed for large-scale genetic interaction studies in the model
yeast Saccharomyces cerevisiae cannot be applied to C.
albicans. Genetic interaction studies have proven to be powerful
genetic tools for the analysis of complex biological processes. Here, we
demonstrate that libraries of C. albicans strains containing
heterozygous mutations in two different genes can be generated and used to study
genetic interactions in C. albicans on a large scale. Double
heterozygous mutants that show more severe phenotypes than strains with single
heterozygous mutations are indicative of genetic interactions through a
phenomenon referred to as complex haploinsufficiency (CHI). We applied this
approach to the study of the RAM (Regulation of Ace2 and Morphogenesis)
signaling network during the morphogenetic transition of C.
albicans from yeast to filamentous growth. Among the genes that
interacted with CBK1, the key signaling kinase of the RAM
pathway, were transcriptional targets of the RAM pathway and the protein kinase
A pathway. Further analysis supports a model in which these two pathways
co-regulate a common set of genes at different stages of filamentation.
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Affiliation(s)
- Nike Bharucha
- Department of Molecular, Cellular, and
Developmental Biology, University of Michigan, Ann Arbor, Michigan, United
States of America
| | - Yeissa Chabrier-Roselló
- Department of Pediatrics, University of
Rochester School of Medicine and Dentistry, Rochester, New York, United States
of America
| | - Tao Xu
- Department of Molecular, Cellular, and
Developmental Biology, University of Michigan, Ann Arbor, Michigan, United
States of America
| | - Cole Johnson
- Department of Molecular, Cellular, and
Developmental Biology, University of Michigan, Ann Arbor, Michigan, United
States of America
| | - Sarah Sobczynski
- Department of Microbiology/Immunology,
University of Rochester School of Medicine and Dentistry, Rochester, New York,
United States of America
| | - Qingxuan Song
- Department of Molecular, Cellular, and
Developmental Biology, University of Michigan, Ann Arbor, Michigan, United
States of America
| | - Craig J. Dobry
- Department of Molecular, Cellular, and
Developmental Biology, University of Michigan, Ann Arbor, Michigan, United
States of America
| | - Matthew J. Eckwahl
- Department of Molecular, Cellular, and
Developmental Biology, University of Michigan, Ann Arbor, Michigan, United
States of America
| | - Christopher P. Anderson
- Department of Molecular, Cellular, and
Developmental Biology, University of Michigan, Ann Arbor, Michigan, United
States of America
| | - Andrew J. Benjamin
- Department of Molecular, Cellular, and
Developmental Biology, University of Michigan, Ann Arbor, Michigan, United
States of America
| | - Anuj Kumar
- Department of Molecular, Cellular, and
Developmental Biology, University of Michigan, Ann Arbor, Michigan, United
States of America
- * E-mail: (DJK); (AK)
| | - Damian J. Krysan
- Department of Pediatrics, University of
Rochester School of Medicine and Dentistry, Rochester, New York, United States
of America
- Department of Microbiology/Immunology,
University of Rochester School of Medicine and Dentistry, Rochester, New York,
United States of America
- * E-mail: (DJK); (AK)
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46
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McDonough KA, Rodriguez A. The myriad roles of cyclic AMP in microbial pathogens: from signal to sword. Nat Rev Microbiol 2011; 10:27-38. [PMID: 22080930 DOI: 10.1038/nrmicro2688] [Citation(s) in RCA: 212] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
All organisms must sense and respond to their external environments, and this signal transduction often involves second messengers such as cyclic nucleotides. One such nucleotide is cyclic AMP, a universal second messenger that is used by diverse forms of life, including mammals, fungi, protozoa and bacteria. In this review, we discuss the many roles of cAMP in bacterial, fungal and protozoan pathogens and its contributions to microbial pathogenesis. These roles include the coordination of intracellular processes, such as virulence gene expression, with extracellular signals from the environment, and the manipulation of host immunity by increasing cAMP levels in host cells during infection.
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Affiliation(s)
- Kathleen A McDonough
- Wadsworth Center, New York State Department of Health, 120 New Scotland Avenue, PO Box 22002, Albany, New York, New York 12201-2002, USA. kathleen.mcdonough@ wadsworth.org
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47
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Hogan DA, Muhlschlegel FA. Candida albicans developmental regulation: adenylyl cyclase as a coincidence detector of parallel signals. Curr Opin Microbiol 2011; 14:682-6. [PMID: 22014725 DOI: 10.1016/j.mib.2011.09.014] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Accepted: 09/27/2011] [Indexed: 11/19/2022]
Abstract
In the healthy individual, Candida albicans is frequently found as a harmless commensal residing in the gastrointestinal tract. However, in the compromised patient, C. albicans may invade the body and cause disease that is associated with poor prognosis and high mortality. The C. albicans adenylyl cyclase, Cyr1, which is required for virulence in animal models, regulates three developmental programs, including invasive filamentous growth, phenotypic switching to a mating-competent cell type, and biofilm formation. Evidence suggests that Cyr1 controls these phenotypes in response to various environmental cues that are present within microbial populations. Additionally, C. albicans secretes an autoregulatory molecule, farnesol, which was recently shown to directly inhibit Cyr1 activity. Below, we summarize recent advances in our understanding of Cyr1-regulated development and discuss the multiple inputs known to positively and negatively regulate cAMP synthesis. We discuss the possibility that Cyr1 acts as a coincidence detector that tightly regulates fungal development in response to parallel environmental stimuli, and highlight ways in which this might occur.
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Affiliation(s)
- Deborah A Hogan
- Department of Microbiology and Immunology, Dartmouth Medical School, Hanover, NH 03755, United States.
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48
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Bai C, Xu XL, Wang HS, Wang YM, Chan FY, Wang Y. Characterization of a hyperactive Cyr1 mutant reveals new regulatory mechanisms for cellular cAMP levels in Candida albicans. Mol Microbiol 2011; 82:879-93. [PMID: 21992526 DOI: 10.1111/j.1365-2958.2011.07859.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The adenylyl cyclase Cyr1 plays a pivotal role in regulating virulence traits in the human fungal pathogen Candida albicans. Although a diverse range of signals are known to activate Cyr1, it remains unclear how low activity is maintained in the absence of stimuli. To uncover negative regulatory elements, we designed a genetic screen to identify mutations in Cyr1 that increase its catalytic activity. We found such a mutant carrying a single Glu1541 to Lys substitution in a conserved motif C-terminal to the catalytic domain. This E1541K mutation caused constitutive filamentous growth, hypersensitivity to stress, resistance to farnesol and overproduction of riboflavin. The mutant phenotype depends on Cap1 and Ras1, two known positive regulators of Cyr1, and the filamentous growth requires Hgc1, a key promoter of hyphal growth. Strikingly, expressing a truncated version of the mutant protein lacking the entire region N-terminal to the catalytic domain in cyr1Δ cells caused a fivefold increase in the cellular cAMP level. Such cells exhibited dramatic enlargement, cytokinetic defects, G1 arrest and impaired hyphal development. Thus, our studies have revealed novel regulatory elements in Cyr1 that normally repress Cyr1 activity to prevent the toxicity of unregulated high cAMP levels.
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Affiliation(s)
- Chen Bai
- Institute of Molecular and Cell Biology, A *STAR (Agency for Science, Technology and Research), Singapore 138673, Singapore
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Roles of Ras1 membrane localization during Candida albicans hyphal growth and farnesol response. EUKARYOTIC CELL 2011; 10:1473-84. [PMID: 21908593 DOI: 10.1128/ec.05153-11] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Many Ras GTPases localize to membranes via C-terminal farnesylation and palmitoylation, and localization regulates function. In Candida albicans, a fungal pathogen of humans, Ras1 links environmental cues to morphogenesis. Here, we report the localization and membrane dynamics of Ras1, and we characterize the roles of conserved C-terminal cysteine residues, C287 and C288, which are predicted sites of palmitoylation and farnesylation, respectively. GFP-Ras1 is localized uniformly to plasma membranes in both yeast and hyphae, yet Ras1 plasma membrane mobility was reduced in hyphae compared to that in yeast. Ras1-C288S was mislocalized to the cytoplasm and could not support hyphal development. Ras1-C287S was present primarily on endomembranes, and strains expressing ras1-C287S were delayed or defective in hyphal induction depending on the medium used. Cells bearing constitutively activated Ras1-C287S or Ras1-C288S, due to a G13V substitution, showed increased filamentation, suggesting that lipid modifications are differentially important for Ras1 activation and effector interactions. The C. albicans autoregulatory molecule, farnesol, inhibits Ras1 signaling through adenylate cyclase and bears structural similarities to the farnesyl molecule that modifies Ras1. At lower concentrations of farnesol, hyphal growth was inhibited but Ras1 plasma membrane association was not altered; higher concentrations of farnesol led to mislocalization of Ras1 and another G protein, Rac1. Furthermore, farnesol inhibited hyphal growth mediated by cytosolic Ras1-C288SG13V, suggesting that farnesol does not act through mechanisms that depend on Ras1 farnesylation. Our findings imply that Ras1 is farnesylated and palmitoylated, and that the Ras1 stimulation of adenylate cyclase-dependent phenotypes can occur in the absence of these lipid modifications.
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Arkowitz RA, Bassilana M. Polarized growth in fungi: symmetry breaking and hyphal formation. Semin Cell Dev Biol 2011; 22:806-15. [PMID: 21906692 DOI: 10.1016/j.semcdb.2011.08.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Revised: 08/16/2011] [Accepted: 08/18/2011] [Indexed: 01/12/2023]
Abstract
Cell shape is a critical determinant for function. The baker's yeast Saccharomyces cerevisiae changes shape in response to its environment, growing by budding in rich nutrients, forming invasive pseudohyphal filaments in nutrient poor conditions and pear shaped shmoos for growth towards a partner during mating. The human opportunistic pathogen Candida albicans can switch from budding to hyphal growth, in response to numerous environmental stimuli to colonize and invade its host. Hyphal growth, typical of filamentous fungi, is not observed in S. cerevisiae. A number of internal cues regulate when and where yeast cells break symmetry leading to polarized growth and ultimately distinct cell shapes. This review discusses how cells break symmetry using the yeast S. cerevisiae paradigm and how polarized growth is initiated and maintained to result in dramatic morphological changes during C. albicans hyphal growth.
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Affiliation(s)
- Robert A Arkowitz
- Centre National de la Recherche Scientifique and Université de Nice-Sophia Antipolis, Institute of Developmental Biology and Cancer, CNRS-UMR6543 Faculté des Sciences, Nice, France.
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