1
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Magliozzi JO, Rands TJ, Shrestha S, Simke WC, Hase NE, Juanes MA, Kelley JB, Goode BL. The roles of yeast formins and their regulators Bud6 and Bil2 in the pheromone response. Mol Biol Cell 2024; 35:ar85. [PMID: 38656798 PMCID: PMC11238086 DOI: 10.1091/mbc.e23-11-0459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 04/09/2024] [Accepted: 04/17/2024] [Indexed: 04/26/2024] Open
Abstract
In response to pheromone Saccharomyces cerevisiae extend a mating projection. This process depends on the formation of polarized actin cables which direct secretion to the mating tip and translocate the nucleus for karyogamy. Here, we demonstrate that proper mating projection formation requires the formin Bni1, as well as the actin nucleation promoting activities of Bud6, but not the formin Bnr1. Further, Bni1 is required for pheromone gradient tracking. Our work also reveals unexpected new functions for Bil2 in the pheromone response. Previously we identified Bil2 as a direct inhibitor of Bnr1 during vegetative cell growth. Here, we show that Bil2 has Bnr1-independent functions in spatially focusing Bni1-GFP at mating projection tips, and in vitro Bil2 and its binding partner Bud6 organize Bni1 into clusters that nucleate actin assembly. bil2∆ cells also display entangled Bni1-generated actin cable arrays and defects in secretory vesicle transport and nuclear positioning. At low pheromone concentrations, bil2∆ cells are delayed in establishing a polarity axis, and at high concentrations they prematurely form a second and a third mating projection. Together, these results suggest that Bil2 promotes the proper formation and timing of mating projections by organizing Bni1 and maintaining a persistent axis of polarized growth.
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Affiliation(s)
| | - Thomas J. Rands
- Department of Biology, Brandeis University, Waltham, MA 02454
| | - Sudati Shrestha
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME 04469
| | - William C Simke
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME 04469
| | - Niklas E. Hase
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME 04469
| | - M. Angeles Juanes
- Department of Biology, Brandeis University, Waltham, MA 02454
- Centro de Investigación Príncipe Felipe, 46012 Valencia, Spain
| | - Joshua B. Kelley
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME 04469
| | - Bruce L. Goode
- Department of Biology, Brandeis University, Waltham, MA 02454
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2
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Simke WC, Johnson CP, Hart AJ, Mayhue S, Craig PL, Sojka S, Kelley JB. Phosphorylation of RGS regulates MAP kinase localization and promotes completion of cytokinesis. Life Sci Alliance 2022; 5:5/10/e202101245. [PMID: 35985794 PMCID: PMC9394524 DOI: 10.26508/lsa.202101245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 07/27/2022] [Accepted: 07/28/2022] [Indexed: 12/03/2022] Open
Abstract
Phosphorylation of the RGS Sst2 alters its subcellular distribution, MAPK localization, and interaction with Kel1, which promotes coordination of polarized growth with completion of cytokinesis. Yeast use the G-protein–coupled receptor signaling pathway to detect and track the mating pheromone. The G-protein–coupled receptor pathway is inhibited by the regulator of G-protein signaling (RGS) Sst2 which induces Gα GTPase activity and inactivation of downstream signaling. G-protein signaling activates the MAPK Fus3, which phosphorylates the RGS; however, the role of this modification is unknown. We found that pheromone-induced RGS phosphorylation peaks early; the phospho-state of RGS controls its localization and influences MAPK spatial distribution. Surprisingly, phosphorylation of the RGS promotes completion of cytokinesis before pheromone-induced growth. Completion of cytokinesis in the presence of pheromone is promoted by the kelch-repeat protein, Kel1 and antagonized by the formin Bni1. We found that RGS complexes with Kel1 and prefers the unphosphorylatable RGS mutant. We also found overexpression of unphosphorylatable RGS exacerbates cytokinetic defects, whereas they are rescued by overexpression of Kel1. These data lead us to a model where Kel1 promotes completion of cytokinesis before pheromone-induced polarity but is inhibited by unphosphorylated RGS binding.
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Affiliation(s)
- William C Simke
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, USA
| | - Cory P Johnson
- Graduate School of Biomedical Science and Engineering, University of Maine, Orono, ME, USA
| | - Andrew J Hart
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, USA
| | - Sari Mayhue
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, USA
| | - P Lucas Craig
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, USA
| | - Savannah Sojka
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, USA
| | - Joshua B Kelley
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, USA .,Graduate School of Biomedical Science and Engineering, University of Maine, Orono, ME, USA
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3
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Abstract
Accurate decoding of spatial chemical landscapes is critical for many cell functions. Eukaryotic cells decode local chemical gradients to orient growth or movement in productive directions. Recent work on yeast model systems, whose gradient sensing pathways display much less complexity than those in animal cells, has suggested new paradigms for how these very small cells successfully exploit information in noisy and dynamic pheromone gradients to identify their mates. Pheromone receptors regulate a polarity circuit centered on the conserved Rho-family GTPase, Cdc42. The polarity circuit contains both positive and negative feedback pathways, allowing spontaneous symmetry breaking and also polarity site disassembly and relocation. Cdc42 orients the actin cytoskeleton, leading to focused vesicle traffic that promotes movement of the polarity site and also reshapes the cortical distribution of receptors at the cell surface. In this article, we review the advances from work on yeasts and compare them with the excitable signaling pathways that have been revealed in chemotactic animal cells. Expected final online publication date for the Annual Review of Biophysics, Volume 51 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Debraj Ghose
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, USA;
| | - Timothy Elston
- Department of Pharmacology, University of North Carolina at Chapel Hill, North Carolina, USA
| | - Daniel Lew
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, USA;
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4
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Adhikari N, McGill IN, Hadwiger JA. MAPK docking motif in the Dictyostelium Gα2 subunit is required for aggregation and transcription factor translocation. Cell Signal 2021; 87:110117. [PMID: 34418534 DOI: 10.1016/j.cellsig.2021.110117] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 08/06/2021] [Accepted: 08/07/2021] [Indexed: 01/05/2023]
Abstract
Some G protein alpha subunits contain a mitogen-activated protein kinase (MAPK) docking motif (D-motif) near the amino terminus that can impact cellular responses to external signals. The Dictyostelium Gα2 G protein subunit is required for chemotaxis to cAMP during the onset of multicellular development and this subunit contains a putative D-motif near the amino terminus. The Gα2 subunit D-motif was altered to examine its potential role in chemotaxis and multicellular development. In gα2- cells the expression of the D-motif mutant (Gα2D-) or wild-type subunit from high copy number vectors rescued cell aggregation but blocked the transition of mounds into slugs. This phenotype was also observed in parental strains with a wild-type gα2 locus indicating that the heterologous Gα2 subunit expression interferes with multicellular morphogenesis. Expression of the Gα2D- subunit from a low copy number vectors in gα2- cells did not rescue aggregation whereas the wild-type Gα2 subunit rescued aggregation efficiently and allowed wild-type morphological development. The Gα2D- and Gα2 subunit were both capable of restoring comparable levels of cAMP stimulated motility and the ability to co-aggregate with wild-type cells implying that the aggregation defect of Gα2D- expressing cells is due to insufficient intercellular signaling. Expression of the Gα2 subunit but not the Gα2D- subunit fully restored the ability of cAMP to stimulate the translocation of the GtaC transcription factor suggesting the D-motif is important for transcription factor regulation. These results suggest that the D-motif of Gα2 plays a role in aggregation and other developmental responses involved with cAMP signaling.
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Affiliation(s)
- Nirakar Adhikari
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078-3020, United States of America
| | - Imani N McGill
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078-3020, United States of America
| | - Jeffrey A Hadwiger
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078-3020, United States of America.
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5
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Gradient Tracking by Yeast GPCRs in a Microfluidics Chamber. Methods Mol Biol 2021. [PMID: 34085275 DOI: 10.1007/978-1-0716-1221-7_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Cells typically exist in a highly dynamic environment, which cannot easily be recreated in culture dishes or microwell plates. Microfluidic devices can provide precise control of the time, dose, and orientation of a stimulus, while simultaneously capturing quantitative single-cell data. The approach is particularly powerful when combined with the genetically tractable yeast model organism. The GPCR pathway in yeast is structurally conserved and functionally interchangeable with those in humans. We describe the implementation of a microfluidic device to investigate morphological and transcriptional responses of yeast to a gradient or pulse administration of a GPCR ligand, the peptide mating pheromone α-factor.
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6
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Jacob B, Drawert B, Yi TM, Petzold L. An arbitrary Lagrangian Eulerian smoothed particle hydrodynamics (ALE-SPH) method with a boundary volume fraction formulation for fluid-structure interaction. ENGINEERING ANALYSIS WITH BOUNDARY ELEMENTS 2021; 128:274-289. [PMID: 34040286 PMCID: PMC8143034 DOI: 10.1016/j.enganabound.2021.04.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We present a new weakly-compressible smoothed particle hydrodynamics (SPH) method capable of modeling non-slip fixed and moving wall boundary conditions. The formulation combines a boundary volume fraction (BVF) wall approach with the transport-velocity SPH method. The resulting method, named SPH-BVF, offers detection of arbitrarily shaped solid walls on-the-fly, with small computational overhead due to its local formulation. This simple framework is capable of solving problems that are difficult or infeasible for standard SPH, namely flows subject to large shear stresses or at moderate Reynolds numbers, and mass transfer in deformable boundaries. In addition, the method extends the transport-velocity formulation to reaction-diffusion transport of mass in Newtonian fluids and linear elastic solids, which is common in biological structures. Taken together, the SPH-BVF method provides a good balance of simplicity and versatility, while avoiding some of the standard obstacles associated with SPH: particle penetration at the boundaries, tension instabilities and anisotropic particle alignments, that hamper SPH from being applied to complex problems such as fluid-structure interaction in a biological system.
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Affiliation(s)
- Bruno Jacob
- Department of Mechanical Engineering, University of California-Santa Barbara, Santa Barbara, California, 93106, USA
| | - Brian Drawert
- Department of Computer Science, University of North Carolina at Asheville, Asheville, North Carolina, 28804, USA
| | - Tau-Mu Yi
- Department of Molecular, Cellular, and Developmental Biology, University of California-Santa Barbara, Santa Barbara, California 93106, USA
| | - Linda Petzold
- Department of Mechanical Engineering, University of California-Santa Barbara, Santa Barbara, California, 93106, USA
- Department of Computer Science, University of California-Santa Barbara, Santa Barbara, California, 93106, USA
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7
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Martínez-Matías N, Chorna N, González-Crespo S, Villanueva L, Montes-Rodríguez I, Melendez-Aponte LM, Roche-Lima A, Carrasquillo-Carrión K, Santiago-Cartagena E, Rymond BC, Babu M, Stagljar I, Rodríguez-Medina JR. Toward the discovery of biological functions associated with the mechanosensor Mtl1p of Saccharomyces cerevisiae via integrative multi-OMICs analysis. Sci Rep 2021; 11:7411. [PMID: 33795741 PMCID: PMC8016984 DOI: 10.1038/s41598-021-86671-8] [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: 12/28/2020] [Accepted: 03/15/2021] [Indexed: 02/06/2023] Open
Abstract
Functional analysis of the Mtl1 protein in Saccharomyces cerevisiae has revealed that this transmembrane sensor endows yeast cells with resistance to oxidative stress through a signaling mechanism called the cell wall integrity pathway (CWI). We observed upregulation of multiple heat shock proteins (HSPs), proteins associated with the formation of stress granules, and the phosphatase subunit of trehalose 6-phosphate synthase which suggests that mtl1Δ strains undergo intrinsic activation of a non-lethal heat stress response. Furthermore, quantitative global proteomic analysis conducted on TMT-labeled proteins combined with metabolome analysis revealed that mtl1Δ strains exhibit decreased levels of metabolites of carboxylic acid metabolism, decreased expression of anabolic enzymes and increased expression of catabolic enzymes involved in the metabolism of amino acids, with enhanced expression of mitochondrial respirasome proteins. These observations support the idea that Mtl1 protein controls the suppression of a non-lethal heat stress response under normal conditions while it plays an important role in metabolic regulatory mechanisms linked to TORC1 signaling that are required to maintain cellular homeostasis and optimal mitochondrial function.
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Affiliation(s)
- Nelson Martínez-Matías
- grid.267033.30000 0004 0462 1680Department of Biochemistry, Medical Sciences Campus, University of Puerto Rico, San Juan, PR 00936-5067 USA
| | - Nataliya Chorna
- grid.267033.30000 0004 0462 1680Department of Biochemistry, Medical Sciences Campus, University of Puerto Rico, San Juan, PR 00936-5067 USA
| | - Sahily González-Crespo
- grid.267033.30000 0004 0462 1680Department of Biochemistry, Medical Sciences Campus, University of Puerto Rico, San Juan, PR 00936-5067 USA
| | - Lilliam Villanueva
- grid.267033.30000 0004 0462 1680Department of Biochemistry, Medical Sciences Campus, University of Puerto Rico, San Juan, PR 00936-5067 USA
| | - Ingrid Montes-Rodríguez
- Comprehensive Cancer Center, University of Puerto Rico, Puerto Rico Medical Center, Rio Piedras, PR 00936-3027 USA
| | - Loyda M. Melendez-Aponte
- grid.267033.30000 0004 0462 1680Department of Biochemistry, Medical Sciences Campus, University of Puerto Rico, San Juan, PR 00936-5067 USA
| | - Abiel Roche-Lima
- grid.267033.30000 0004 0462 1680Department of Biochemistry, Medical Sciences Campus, University of Puerto Rico, San Juan, PR 00936-5067 USA
| | - Kelvin Carrasquillo-Carrión
- grid.267033.30000 0004 0462 1680Department of Biochemistry, Medical Sciences Campus, University of Puerto Rico, San Juan, PR 00936-5067 USA
| | - Ednalise Santiago-Cartagena
- grid.267033.30000 0004 0462 1680Department of Biochemistry, Medical Sciences Campus, University of Puerto Rico, San Juan, PR 00936-5067 USA
| | - Brian C. Rymond
- grid.266539.d0000 0004 1936 8438Department of Biology, University of Kentucky, Lexington, KY 40506 USA
| | - Mohan Babu
- grid.57926.3f0000 0004 1936 9131Department of Biochemistry, University of Regina, Regina, SK S4S 0A2 Canada
| | - Igor Stagljar
- grid.17063.330000 0001 2157 2938Donnelly Centre, Department of Biochemistry, Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 3E1 Canada ,grid.482535.d0000 0004 4663 8413Mediterranean Institute for Life Sciences, Split, Croatia
| | - José R. Rodríguez-Medina
- grid.267033.30000 0004 0462 1680Department of Biochemistry, Medical Sciences Campus, University of Puerto Rico, San Juan, PR 00936-5067 USA
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8
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Vázquez-Ibarra A, Rodríguez-Martínez G, Guerrero-Serrano G, Kawasaki L, Ongay-Larios L, Coria R. Negative feedback-loop mechanisms regulating HOG- and pheromone-MAPK signaling in yeast. Curr Genet 2020; 66:867-880. [PMID: 32564133 DOI: 10.1007/s00294-020-01089-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 06/08/2020] [Accepted: 06/10/2020] [Indexed: 11/28/2022]
Abstract
The pheromone response and the high osmolarity glycerol (HOG) pathways are considered the prototypical MAPK signaling systems. They are the best-understood pathways in eukaryotic cells, yet they continue to provide insights in how cells relate with the environment. These systems are subjected to tight regulatory circuits to prevent hyperactivation in length and intensity. Failure to do this may be a matter of life or death specially for unicellular organisms such as Saccharomyces cerevisiae. The signaling pathways are fine-tuned by positive and negative feedback loops exerted by pivotal control elements that allow precise responses to specific stimuli, despite the fact that some elements of the systems are common to different signaling pathways. Here we describe the experimentally proven negative feedback loops that modulate the pheromone response and the HOG pathways. As described in this review, MAP kinases are central mechanistic components of these feedback loops. They have the capacity to modulate basal signaling activity, a fast extranuclear response, and a longer-lasting transcriptional process.
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Affiliation(s)
- Araceli Vázquez-Ibarra
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510, México City, México
| | - Griselda Rodríguez-Martínez
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510, México City, México
| | | | - Laura Kawasaki
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510, México City, México
| | - Laura Ongay-Larios
- Unidad de Biología Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510, México City, México
| | - Roberto Coria
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, 04510, México City, México.
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9
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Rangarajan N, Gordy CL, Askew L, Bevill SM, Elston TC, Errede B, Hurst JH, Kelley JB, Sheetz JB, Suzuki SK, Valentin NH, Young E, Dohlman HG. Systematic analysis of F-box proteins reveals a new branch of the yeast mating pathway. J Biol Chem 2019; 294:14717-14731. [PMID: 31399514 DOI: 10.1074/jbc.ra119.010063] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 08/06/2019] [Indexed: 11/06/2022] Open
Abstract
The mating pathway in yeast Saccharomyces cerevisiae has long been used to reveal new mechanisms of signal transduction. The pathway comprises a pheromone receptor, a heterotrimeric G protein, and intracellular effectors of morphogenesis and transcription. Polarized cell growth, in the direction of a potential mating partner, is accomplished by the G-protein βγ subunits and the small G-protein Cdc42. Transcription induction, needed for cell-cell fusion, is mediated by Gβγ and the mitogen-activated protein kinase (MAPK) scaffold protein Ste5. A potential third pathway is initiated by the G-protein α subunit Gpa1. Gpa1 signaling was shown previously to involve the F-box adaptor protein Dia2 and an endosomal effector protein, the phosphatidylinositol 3-kinase Vps34. Vps34 is also required for proper vacuolar sorting and autophagy. Here, using a panel of reporter assays, we demonstrate that mating pheromone stimulates vacuolar targeting of a cytoplasmic reporter protein and that this process depends on Vps34. Through a systematic analysis of F-box deletion mutants, we show that Dia2 is required to sustain pheromone-induced vacuolar targeting. We also found that other F-box proteins selectively regulate morphogenesis (Ydr306, renamed Pfu1) and transcription (Ucc1). These findings point to the existence of a new and distinct branch of the pheromone-signaling pathway, one that likely leads to vacuolar engulfment of cytoplasmic proteins and recycling of cellular contents in preparation for mating.
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Affiliation(s)
- Nambirajan Rangarajan
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Claire L Gordy
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Lauren Askew
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Samantha M Bevill
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Timothy C Elston
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Beverly Errede
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Jillian H Hurst
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Joshua B Kelley
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Joshua B Sheetz
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Sara Kimiko Suzuki
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599.,Curriculum in Bioinformatics and Computational Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Natalie H Valentin
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Everett Young
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Henrik G Dohlman
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
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10
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Waszczak N, DeFlorio R, Ismael A, Cheng N, Stone DE, Metodiev MV. Quantitative proteomics reveals a Gα/MAPK signaling hub that controls pheromone-induced cellular polarization in yeast. J Proteomics 2019; 207:103467. [PMID: 31351147 DOI: 10.1016/j.jprot.2019.103467] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 07/20/2019] [Accepted: 07/23/2019] [Indexed: 12/26/2022]
Abstract
The mating-specific yeast Gα controls pheromone signaling by sequestering Gβγ and by regulating the Fus3 MAP kinase. Disrupting Gα-Fus3 interaction leads to severe defects in chemotropism. Because Gα concentrates at the chemotropic growth site where Fus3 is required for the phosphorylation of two known targets, we screened for additional proteins whose phosphorylation depends on pheromone stimulation and Gα-Fus3 interaction. Using a mutant form of Gα severely defective in Fus3-binding, GαDSD, and quantitative mass spectrometry, fourteen proteins were identified as potential targets of Gα-recruited Fus3, ten of which were previously implicated in cell polarity and morphogenesis. To explore the biological relevance of these findings, we focused on the Spa2 polarisome protein, which was hypophosphorylated on multiple serine residues in pheromone-treated GαDSD cells. Six sites were mutagenized to create the Spa26XSA mutant protein. Spa26XSA exhibited increased affinity for Fus3, consistent with a kinase-substrate interaction, and Spa26XSA cells exhibited dramatic defects in gradient sensing and zygote formation. These results suggest that Gα promotes the phosphorylation of Spa2 by Fus3 at the cortex of pheromone-stimulated cells, and that this mechanism plays a role in chemotropism. How the Gα-Fus3 signaling hub affects the other putative targets identified here has yet to be determined. SIGNIFICANCE: Previously, interaction between the G alpha protein, Gpa1, and the MAPK of the pheromone response pathway, Fus3, was shown to be important for efficient sensing of the pheromone gradient and for the maintenance of cell polarity during mating. Here we show that the underlying molecular mechanisms involve the phosphorylation of specific cortical targets of Gpa1/Fus3. These have been identified by quantitative phosphoproteomics using a mutant of Gpa1, which is defective in interacting with Fus3. One of these targets is the polarisome protein Spa2. Alanine substitution of the Spa2 phosphorylation sites targeted by Gpa1/Fus3 lead to a dramatic defect in pheromone gradient sensing and zygote formation. These results reveal how the G alpha protein and the MAPK control cell polarity in a prototypical model system. Our results have wider significance as similar mechanisms exist in higher eukaryotes and are involved in important biological such as neuron development, immunity, and cancer cell metastasis.
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Affiliation(s)
- Nicholaz Waszczak
- Department of Biological Sciences, University of Illinois at Chicago, 900 South Ashland Ave, Chicago, USA
| | - Reagan DeFlorio
- Department of Biological Sciences, University of Illinois at Chicago, 900 South Ashland Ave, Chicago, USA
| | - Amber Ismael
- Department of Biological Sciences, University of Illinois at Chicago, 900 South Ashland Ave, Chicago, USA
| | - Naiyuan Cheng
- Department of Biological Sciences, University of Illinois at Chicago, 900 South Ashland Ave, Chicago, USA
| | - David E Stone
- Department of Biological Sciences, University of Illinois at Chicago, 900 South Ashland Ave, Chicago, USA.
| | - Metodi V Metodiev
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, UK.
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11
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Shellhammer JP, Pomeroy AE, Li Y, Dujmusic L, Elston TC, Hao N, Dohlman HG. Quantitative analysis of the yeast pheromone pathway. Yeast 2019; 36:495-518. [PMID: 31022772 DOI: 10.1002/yea.3395] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 04/10/2019] [Accepted: 04/16/2019] [Indexed: 01/04/2023] Open
Abstract
The pheromone response pathway of the yeast Saccharomyces cerevisiae is a well-established model for the study of G proteins and mitogen-activated protein kinase (MAPK) cascades. Our longstanding ability to combine sophisticated genetic approaches with established functional assays has provided a thorough understanding of signalling mechanisms and regulation. In this report, we compare new and established methods used to quantify pheromone-dependent MAPK phosphorylation, transcriptional induction, mating morphogenesis, and gradient tracking. These include both single-cell and population-based assays of activity. We describe several technical advances, provide example data for benchmark mutants, highlight important differences between newer and established methodologies, and compare the advantages and disadvantages of each as applied to the yeast model. Quantitative measurements of pathway activity have been used to develop mathematical models and reveal new regulatory mechanisms in yeast. It is our expectation that experimental and computational approaches developed in yeast may eventually be adapted to human systems biology and pharmacology.
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Affiliation(s)
- James P Shellhammer
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Amy E Pomeroy
- Curriculum in Bioinformatics and Computational Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Yang Li
- Division of Biological Sciences, University of California San Diego, San Diego, CA, 92093, USA
| | - Lorena Dujmusic
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Timothy C Elston
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.,Curriculum in Bioinformatics and Computational Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Nan Hao
- Division of Biological Sciences, University of California San Diego, San Diego, CA, 92093, USA
| | - Henrik G Dohlman
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.,Curriculum in Bioinformatics and Computational Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
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12
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Abstract
This article provides an overview of sexual reproduction in the ascomycetes, a phylum of fungi that is named after the specialized sacs or "asci" that hold the sexual spores. They have therefore also been referred to as the Sac Fungi due to these characteristic structures that typically contain four to eight ascospores. Ascomycetes are morphologically diverse and include single-celled yeasts, filamentous fungi, and more complex cup fungi. The sexual cycles of many species, including those of the model yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe and the filamentous saprobes Neurospora crassa, Aspergillus nidulans, and Podospora anserina, have been examined in depth. In addition, sexual or parasexual cycles have been uncovered in important human pathogens such as Candida albicans and Aspergillus fumigatus, as well as in plant pathogens such as Fusarium graminearum and Cochliobolus heterostrophus. We summarize what is known about sexual fecundity in ascomycetes, examine how structural changes at the mating-type locus dictate sexual behavior, and discuss recent studies that reveal that pheromone signaling pathways can be repurposed to serve cellular roles unrelated to sex.
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Kompella PS, Moses AM, Peisajovich SG. Introduction of Premature Stop Codons as an Evolutionary Strategy To Rescue Signaling Network Function. ACS Synth Biol 2017; 6:446-454. [PMID: 27935292 DOI: 10.1021/acssynbio.6b00142] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The cellular concentrations of key components of signaling networks are tightly regulated, as deviations from their optimal ranges can have negative effects on signaling function. For example, overexpression of the yeast mating pathway mitogen-activated protein kinase (MAPK) Fus3 decreases pathway output, in part by sequestering individual components away from functional multiprotein complexes. Using a synthetic biology approach, we investigated potential mechanisms by which selection could compensate for a decrease in signaling activity caused by overexpression of Fus3. We overexpressed a library of random mutants of Fus3 and used cell sorting to select variants that rescued mating pathway activity. Our results uncovered that one remarkable way in which selection can compensate for protein overexpression is by introducing premature stop codons at permitted positions. Because of the low efficiency with which premature stop codons are read through, the resulting cellular concentration of active Fus3 returns to values within the range required for proper signaling. Our results underscore the importance of interpreting genotypic variation at the systems rather than at the individual gene level, as mutations can have opposite effects on protein and network function.
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Affiliation(s)
- Purnima S. Kompella
- Department of Cell and Systems
Biology, University of Toronto 25 Harbord Street, Toronto, Ontario M5S 3G5, Canada
| | - Alan M. Moses
- Department of Cell and Systems
Biology, University of Toronto 25 Harbord Street, Toronto, Ontario M5S 3G5, Canada
| | - Sergio G. Peisajovich
- Department of Cell and Systems
Biology, University of Toronto 25 Harbord Street, Toronto, Ontario M5S 3G5, Canada
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14
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Atay O, Skotheim JM. Spatial and temporal signal processing and decision making by MAPK pathways. J Cell Biol 2017; 216:317-330. [PMID: 28043970 PMCID: PMC5294789 DOI: 10.1083/jcb.201609124] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 11/25/2016] [Accepted: 12/12/2016] [Indexed: 01/14/2023] Open
Abstract
Recent studies show that MAPK pathways perform exquisite spatial and temporal signal processing. This review discusses the mechanisms that process dynamic inputs into graded output responses, the role of positive and negative feedbacks, and feedforward regulation. Mitogen-activated protein kinase (MAPK) pathways are conserved from yeast to man and regulate a variety of cellular processes, including proliferation and differentiation. Recent developments show how MAPK pathways perform exquisite spatial and temporal signal processing and underscores the importance of studying the dynamics of signaling pathways to understand their physiological response. The importance of dynamic mechanisms that process input signals into graded downstream responses has been demonstrated in the pheromone-induced and osmotic stress–induced MAPK pathways in yeast and in the mammalian extracellular signal-regulated kinase MAPK pathway. Particularly, recent studies in the yeast pheromone response have shown how positive feedback generates switches, negative feedback enables gradient detection, and coherent feedforward regulation underlies cellular memory. More generally, a new wave of quantitative single-cell studies has begun to elucidate how signaling dynamics determine cell physiology and represents a paradigm shift from descriptive to predictive biology.
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Affiliation(s)
- Oguzhan Atay
- Department of Biology, Stanford University, Stanford, CA 94305
| | - Jan M Skotheim
- Department of Biology, Stanford University, Stanford, CA 94305
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15
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Wang M, Zhang M, Li L, Dong Y, Jiang Y, Liu K, Zhang R, Jiang B, Niu K, Fang X. Role of Trichoderma reesei mitogen-activated protein kinases (MAPKs) in cellulase formation. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:99. [PMID: 28435444 PMCID: PMC5397809 DOI: 10.1186/s13068-017-0789-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 04/12/2017] [Indexed: 05/02/2023]
Abstract
BACKGROUND Despite being the most important cellulase producer, the cellulase-regulating carbon source signal transduction processes in Trichoderma reesei are largely unknown. Elucidating these processes is the key for unveiling how external carbon sources regulate cellulase formation, and ultimately for the improvement of cellulase production and biofuel production from lignocellulose. RESULTS In this work, the role of the mitogen-activated protein kinase (MAPK) signal transduction pathways on cellulase formation was investigated. The deletion of yeast FUS3-like tmk1 in T. reesei leads to improved growth and significantly improved cellulase formation. However, tmk1 deletion has no effect on the transcription of cellulase-coding genes. The involvement of the cell wall integrity maintenance governing yeast Slt2-like Tmk2 in cellulase formation was investigated by overexpressing tmk3 in T. reesei Δtmk2 to restore cell wall integrity. Transcriptional analysis found little changes in cellulase-coding genes between T. reesei parent, Δtmk2, and Δtmk2::OEtmk3 strains. Cell wall integrity decreased in T. reesei Δtmk2 over the parent strain and restored in Δtmk2::OEtmk3. Meanwhile, cellulase formation is increased in T. reesei Δtmk2 and then decreased in T. reesei Δtmk2::OEtmk3. CONCLUSIONS These investigations elucidate the role of Tmk1 and Tmk2 on cellulase formation: they repress cellulase formation, respectively, by repressing growth and maintaining cell wall integrity, while neither MAPK regulates the transcription of cellulase-coding genes. This work, together with the previous investigations, suggests that all MAPKs are involved in cellulase formation, while Tmk3 is the only MAPK involved in signal transduction for the regulation of cellulase expression on the transcriptional level.
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Affiliation(s)
- Mingyu Wang
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan, China
| | - Meiling Zhang
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan, China
| | - Ling Li
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan, China
| | - Yanmei Dong
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan, China
| | - Yi Jiang
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan, China
| | - Kuimei Liu
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan, China
| | - Ruiqin Zhang
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan, China
| | - Baojie Jiang
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan, China
| | - Kangle Niu
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan, China
| | - Xu Fang
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Jinan, China
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Ismael A, Tian W, Waszczak N, Wang X, Cao Y, Suchkov D, Bar E, Metodiev MV, Liang J, Arkowitz RA, Stone DE. Gβ promotes pheromone receptor polarization and yeast chemotropism by inhibiting receptor phosphorylation. Sci Signal 2016; 9:ra38. [PMID: 27072657 DOI: 10.1126/scisignal.aad4376] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Gradient-directed cell migration (chemotaxis) and growth (chemotropism) are processes that are essential to the development and life cycles of all species. Cells use surface receptors to sense the shallow chemical gradients that elicit chemotaxis and chemotropism. Slight asymmetries in receptor activation are amplified by downstream signaling systems, which ultimately induce dynamic reorganization of the cytoskeleton. During the mating response of budding yeast, a model chemotropic system, the pheromone receptors on the plasma membrane polarize to the side of the cell closest to the stimulus. Although receptor polarization occurs before and independently of actin cable-dependent delivery of vesicles to the plasma membrane (directed secretion), it requires receptor internalization. Phosphorylation of pheromone receptors by yeast casein kinase 1 or 2 (Yck1/2) stimulates their internalization. We showed that the pheromone-responsive Gβγ dimer promotes the polarization of the pheromone receptor by interacting with Yck1/2 and locally inhibiting receptor phosphorylation. We also found that receptor phosphorylation is essential for chemotropism, independently of its role in inducing receptor internalization. A mathematical model supports the idea that the interaction between Gβγ and Yck1/2 results in differential phosphorylation and internalization of the pheromone receptor and accounts for its polarization before the initiation of directed secretion.
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Affiliation(s)
- Amber Ismael
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Wei Tian
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Nicholas Waszczak
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Xin Wang
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Youfang Cao
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Dmitry Suchkov
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Eli Bar
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Metodi V Metodiev
- School of Biological Sciences, University of Essex, Essex CO4 3SQ, UK
| | - Jie Liang
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Robert A Arkowitz
- CNRS UMR7277/INSERM UMR1091/Université Nice-Sophia Antipolis, Institute of Biology Valrose, 06108 Nice Cedex 2, France
| | - David E Stone
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA.
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