scholarly journals Calmodulin controls organization of the actin cytoskeleton via regulation of phosphatidylinositol (4,5)-bisphosphate synthesis in Saccharomyces cerevisiae

2002 ◽  
Vol 366 (3) ◽  
pp. 945-951 ◽  
Author(s):  
Sylvane DESRIVIÈRES ◽  
Frank T. COOKE ◽  
Helena MORALES-JOHANSSON ◽  
Peter J. PARKER ◽  
Michael N. HALL
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Actin Cytoskeleton ◽  
Membrane Trafficking ◽  
Binding Protein ◽  
Temperature Sensitive ◽  
Cellular Processes ◽  
Wide Range ◽  
Phosphatidylinositol 4 ◽  
Calmodulin Mutant

Phosphoinositides regulate a wide range of cellular processes, including proliferation, survival, cytoskeleton remodelling and membrane trafficking, yet the mechanisms controlling the kinases, phosphatases and lipases that modulate phosphoinositide levels are poorly understood. In the present study, we describe a mechanism controlling MSS4, the sole phosphatidylinositol (4)-phosphate 5-kinase in Saccharomyces cerevisiae. Mutations in MSS4 and CMD1, encoding the small Ca2+-binding protein calmodulin, confer similar phenotypes, including loss of viability and defects in endocytosis and in organization of the actin cytoskeleton. Overexpression of MSS4 suppresses the growth and actin defects of cmd1-226, a temperature-sensitive calmodulin mutant which is defective in the organization of the actin cytoskeleton. Finally, the cmd1-226 mutant exhibits reduced levels of phosphatidylinositol (4,5)-bisphosphate. These findings suggest that calmodulin positively controls MSS4 activity and thereby the actin cytoskeleton.

scholarly journals ROM7/BEM4 encodes a novel protein that interacts with the Rho1p small GTP-binding protein in Saccharomyces cerevisiae.

1996 ◽  
Vol 16 (8) ◽  
pp. 4396-4403 ◽  
Author(s):  
H Hirano ◽  
K Tanaka ◽  
K Ozaki ◽  
H Imamura ◽  
H Kohno ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Binding Protein ◽  
Free Form ◽  
Nucleotide Sequencing ◽  
Temperature Sensitive ◽  
Gtp Binding Protein ◽  
Exchange Factor ◽  
Dominant Negative Mutation ◽  
Gtp Binding ◽  
Novel Protein

The RHO1 gene encodes a homolog of the mammalian RhoA small GTP-binding protein in the yeast Saccharomyces cerevisiae. Rho1p is localized at the growth site and is required for bud formation. The RHO1(G22S, D125N) mutation is a temperature-sensitive and dominant negative mutation of RHO1, and a multicopy suppressor of RHO1(G22S, D125N), ROM7, was isolated. Nucleotide sequencing of ROM7 revealed that it is identical to the BEM4 gene (GenBank accession number L27816), although its physiological function has not yet been reported. Disruption of BEM4 resulted in the cold- and temperature-sensitive growth phenotypes, and cells of the deltabem4 mutant showed abnormal morphology, suggesting that BEM4 is involved in the budding process. The temperature-sensitive growth phenotype was suppressed by overexpression of RHO1, ROM2, which encodes a Rho1p-specific GDP/GTP exchange factor, or PKC1, which encodes a target of Rho1p. Moreover, glucan synthase activity, which is activated by Rho1p, was significantly reduced in the deltabem4 mutant. Two-hybrid and biochemical experiments revealed that Bem4p directly interacts with the nucleotide-free form of Rho1p and, to lesser extents, with the GDP- and GTP-bound forms of Rho1p, although Bem4p showed neither GDP/GTP exchange factor, GDP dissociation inhibitor, nor GTPase-activating protein activity toward Rho1p. These results indicate that Bem4p is a novel protein directly interacting with Rho1p and is involved in the RHO1-mediated signaling pathway.

scholarly journals Bni1p Regulates Microtubule-Dependent Nuclear Migration through the Actin Cytoskeleton in Saccharomyces cerevisiae

1999 ◽  
Vol 19 (12) ◽  
pp. 8016-8027 ◽  
Author(s):  
Takeshi Fujiwara ◽  
Kazuma Tanaka ◽  
Eiji Inoue ◽  
Mitsuhiro Kikyo ◽  
Yoshimi Takai
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Actin Cytoskeleton ◽  
Nuclear Migration ◽  
Growth Defect ◽  
Temperature Sensitive ◽  
Cortical Actin ◽  
Synthetic Lethal ◽  
Downstream Target ◽  
Synthetically Lethal ◽  
Mother Cells

ABSTRACT The RHO1 gene encodes a yeast homolog of the mammalian RhoA protein. Rho1p is localized to the growth sites and is required for bud formation. We have recently shown that Bni1p is one of the potential downstream target molecules of Rho1p. The BNI1gene is implicated in cytokinesis and the establishment of cell polarity in Saccharomyces cerevisiae but is not essential for cell viability. In this study, we screened for mutations that were synthetically lethal in combination with a bni1 mutation and isolated two genes. They were the previously identifiedPAC1 and NIP100 genes, both of which are implicated in nuclear migration in S. cerevisiae. Pac1p is a homolog of human LIS1, which is required for brain development, whereas Nip100p is a homolog of rat p150Glued, a component of the dynein-activated dynactin complex. Disruption ofBNI1 in either the pac1 or nip100mutant resulted in an enhanced defect in nuclear migration, leading to the formation of binucleate mother cells. The arp1 bni1mutant showed a synthetic lethal phenotype while the cin8 bni1 mutant did not, suggesting that Bni1p functions in a kinesin pathway but not in the dynein pathway. Cells of the pac1 bni1 and nip100 bni1 mutants exhibited a random distribution of cortical actin patches. Cells of the pac1 act1-4 mutant showed temperature-sensitive growth and a nuclear migration defect. These results indicate that Bni1p regulates microtubule-dependent nuclear migration through the actin cytoskeleton. Bni1p lacking the Rho-binding region did not suppress the pac1 bni1 growth defect, suggesting a requirement for the Rho1p-Bni1p interaction in microtubule function.

Signalling functions for sphingolipid long-chain bases in Saccharomyces cerevisiae

2005 ◽  
Vol 33 (5) ◽  
pp. 1170-1173 ◽  
Author(s):  
K. Liu ◽  
X. Zhang ◽  
C. Sumanasekera ◽  
R.L. Lester ◽  
R.C. Dickson
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Kinase ◽  
Second Messengers ◽  
Dependent Protein Kinase ◽  
Yeast Saccharomyces Cerevisiae ◽  
Signalling Molecules ◽  
Cellular Processes ◽  
Wide Range ◽  
Dependent Protein ◽  
Long Chain

Over the past several years, studies of sphingolipid functions in the baker's yeast Saccharomyces cerevisiae have revealed that the sphingoid LCBs (long-chain bases), dihydrosphingosine and PHS (phytosphingosine), are important signalling molecules or second messengers under heat stress and during non-stressed conditions. LCBs are now recognized as regulators of AGC-type protein kinase (where AGC stands for protein kinases A, G and C) Pkh1 and Pkh2, which are homologues of mammalian phosphoinositide-dependent protein kinase 1. LCBs were previously shown to activate Pkh1 and Pkh2, which then activate the downstream protein kinase Pkc1. We have recently demonstrated that PHS stimulates Pkh1 to activate additional downstream kinases including Ypk1, Ypk2 and Sch9. We have also found that PHS acts downstream of Pkh1 and partially activates Ypk1, Ypk2 and Sch9. These kinases control a wide range of cellular processes including growth, cell wall integrity, stress resistance, endocytosis and aging. As we learn more about the cellular processes controlled by Ypk1, Ypk2 and Sch9, we will have a far greater appreciation of LCBs as second messengers.

scholarly journals The RhoGEF Trio: A Protein with a Wide Range of Functions in the Vascular Endothelium

2021 ◽  
Vol 22 (18) ◽  
pp. 10168
Author(s):  
Lanette Kempers ◽  
Amber J. M. Driessen ◽  
Jos van Rijssel ◽  
Martijn A. Nolte ◽  
Jaap D. van Buul
Keyword(s):  
Actin Cytoskeleton ◽  
Cell Function ◽  
Small Gtpases ◽  
Nucleotide Exchange ◽  
Endothelial Cell Function ◽  
Cellular Processes ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factors ◽  
Wide Range ◽  
Range Of Functions

Many cellular processes are controlled by small GTPases, which can be activated by guanine nucleotide exchange factors (GEFs). The RhoGEF Trio contains two GEF domains that differentially activate the small GTPases such as Rac1/RhoG and RhoA. These small RhoGTPases are mainly involved in the remodeling of the actin cytoskeleton. In the endothelium, they regulate junctional stabilization and play a crucial role in angiogenesis and endothelial barrier integrity. Multiple extracellular signals originating from different vascular processes can influence the activity of Trio and thereby the regulation of the forementioned small GTPases and actin cytoskeleton. This review elucidates how various signals regulate Trio in a distinct manner, resulting in different functional outcomes that are crucial for endothelial cell function in response to inflammation.

scholarly journals The Saccharomyces cerevisiae SDA1 gene is required for actin cytoskeleton organization and cell cycle progression

2000 ◽  
Vol 113 (7) ◽  
pp. 1199-1211
Author(s):  
G. Buscemi ◽  
F. Saracino ◽  
D. Masnada ◽  
M.L. Carbone
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Dna Replication ◽  
Actin Cytoskeleton ◽  
Cell Cycle Progression ◽  
Temperature Sensitive ◽  
Permissive Temperature ◽  
Cycle Progression ◽  
Cytoskeleton Organization ◽  
Actin Cytoskeleton Organization

The organization of the actin cytoskeleton is essential for several cellular processes. Here we report the characterization of a Saccharomyces cerevisiae novel gene, SDA1, encoding a highly conserved protein, which is essential for cell viability and is localized in the nucleus. Depletion or inactivation of Sda1 cause cell cycle arrest in G(1) by blocking both budding and DNA replication, without loss of viability. Furthermore, sda1-1 temperature-sensitive mutant cells arrest at the non-permissive temperature mostly without detectable structures of polymerized actin, although a normal actin protein level is maintained, indicating that Sda1 is required for proper organization of the actin cytoskeleton. To our knowledge, this is the first mutation shown to cause such a phenotype. Recovery of Sda1 activity restores proper assembly of actin structures, as well as budding and DNA replication. Furthermore we show that direct actin perturbation, either in sda1-1 or in cdc28-13 cells released from G(1) block, prevents recovery of budding and DNA replication. We also show that the block in G(1) caused by loss of Sda1 function is independent of Swe1. Altogether our results suggest that disruption of F-actin structure can block cell cycle progression in G(1) and that Sda1 is involved in the control of the actin cytoskeleton.

scholarly journals The oxysterol-binding protein superfamily: new concepts and old proteins

2012 ◽  
Vol 40 (2) ◽  
pp. 469-473 ◽  
Author(s):  
Michelle L. Villasmil ◽  
Vytas A. Bankaitis ◽  
Carl J. Mousley
Keyword(s):  
Lipid Metabolism ◽  
Membrane Trafficking ◽  
Transcriptional Control ◽  
Binding Protein ◽  
Lipid Binding ◽  
Oxysterol Binding Protein ◽  
New Concepts ◽  
Endosomal Membranes ◽  
Phosphatidylinositol 4 ◽  
Golgi Network

The Kes1 OSBP (oxysterol-binding protein) is a key regulator of membrane trafficking through the TGN (trans-Golgi network) and endosomal membranes. We demonstrated recently that Kes1 acts as a sterol-regulated rheostat for TGN/endosomal phosphatidylinositol 4-phosphate signalling. Kes1 utilizes its dual lipid-binding activities to integrate endosomal lipid metabolism with TORC1 (target of rapamycin complex 1)-dependent proliferative pathways and transcriptional control of nutrient signalling.

scholarly journals GOLPH3 drives cell migration by promoting Golgi reorientation and directional trafficking to the leading edge

2016 ◽  
Vol 27 (24) ◽  
pp. 3828-3840 ◽  
Author(s):  
Mengke Xing ◽  
Marshall C. Peterman ◽  
Robert L. Davis ◽  
Karen Oegema ◽  
Andrew K. Shiau ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Cell Migration ◽  
Actin Cytoskeleton ◽  
Membrane Trafficking ◽  
Leading Edge ◽  
Invasion And Metastasis ◽  
Oncogenic Driver ◽  
Phosphatidylinositol 4 ◽  
Directional Cell Migration ◽  
Insight Into

The mechanism of directional cell migration remains an important problem, with relevance to cancer invasion and metastasis. GOLPH3 is a common oncogenic driver of human cancers, and is the first oncogene that functions at the Golgi in trafficking to the plasma membrane. Overexpression of GOLPH3 is reported to drive enhanced cell migration. Here we show that the phosphatidylinositol-4-phosphate/GOLPH3/myosin 18A/F-actin pathway that is critical for Golgi–to–plasma membrane trafficking is necessary and limiting for directional cell migration. By linking the Golgi to the actin cytoskeleton, GOLPH3 promotes reorientation of the Golgi toward the leading edge. GOLPH3 also promotes reorientation of lysosomes (but not other organelles) toward the leading edge. However, lysosome function is dispensable for migration and the GOLPH3 dependence of lysosome movement is indirect, via GOLPH3’s effect on the Golgi. By driving reorientation of the Golgi to the leading edge and driving forward trafficking, particularly to the leading edge, overexpression of GOLPH3 drives trafficking to the leading edge of the cell, which is functionally important for directional cell migration. Our identification of a novel pathway for Golgi reorientation controlled by GOLPH3 provides new insight into the mechanism of directional cell migration with important implications for understanding GOLPH3’s role in cancer.

PI4P/PS countertransport by ORP10 at ER–endosome membrane contact sites regulates endosome fission

2021 ◽  
Vol 221 (1) ◽  
Author(s):  
Asami Kawasaki ◽  
Akiko Sakai ◽  
Hiroki Nakanishi ◽  
Junya Hasegawa ◽  
Tomohiko Taguchi ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Binding Protein ◽  
Dependent Manner ◽  
Oxysterol Binding Protein ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Lipid Exchange ◽  
Membrane Contact ◽  
Phosphatidylinositol 4

Membrane contact sites (MCSs) serve as a zone for nonvesicular lipid transport by oxysterol-binding protein (OSBP)-related proteins (ORPs). ORPs mediate lipid countertransport, in which two distinct lipids are transported counterdirectionally. How such lipid countertransport controls specific biological functions, however, remains elusive. We report that lipid countertransport by ORP10 at ER–endosome MCSs regulates retrograde membrane trafficking. ORP10, together with ORP9 and VAP, formed ER–endosome MCSs in a phosphatidylinositol 4-phosphate (PI4P)-dependent manner. ORP10 exhibited a lipid exchange activity toward its ligands, PI4P and phosphatidylserine (PS), between liposomes in vitro, and between the ER and endosomes in situ. Cell biological analysis demonstrated that ORP10 supplies a pool of PS from the ER, in exchange for PI4P, to endosomes where the PS-binding protein EHD1 is recruited to facilitate endosome fission. Our study highlights a novel lipid exchange at ER–endosome MCSs as a nonenzymatic PI4P-to-PS conversion mechanism that organizes membrane remodeling during retrograde membrane trafficking.

scholarly journals Activity and Trafficking of Copper-Transporting ATPases in Tumor Development and Defense against Platinum-Based Drugs

Cells ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 1080 ◽  
Author(s):  
Raffaella Petruzzelli ◽  
Roman S. Polishchuk
Keyword(s):  
Tumor Cells ◽  
Membrane Trafficking ◽  
Tumor Development ◽  
Current Data ◽  
Malignant Cells ◽  
Potential Toxicity ◽  
Cellular Processes ◽  
Wide Range ◽  
Cu Homeostasis

Membrane trafficking pathways emanating from the Golgi regulate a wide range of cellular processes. One of these is the maintenance of copper (Cu) homeostasis operated by the Golgi-localized Cu-transporting ATPases ATP7A and ATP7B. At the Golgi, these proteins supply Cu to newly synthesized enzymes which use this metal as a cofactor to catalyze a number of vitally important biochemical reactions. However, in response to elevated Cu, the Golgi exports ATP7A/B to post-Golgi sites where they promote sequestration and efflux of excess Cu to limit its potential toxicity. Growing tumors actively consume Cu and employ ATP7A/B to regulate the availability of this metal for oncogenic enzymes such as LOX and LOX-like proteins, which confer higher invasiveness to malignant cells. Furthermore, ATP7A/B activity and trafficking allow tumor cells to detoxify platinum (Pt)-based drugs (like cisplatin), which are used for the chemotherapy of different solid tumors. Despite these noted activities of ATP7A/B that favor oncogenic processes, the mechanisms that regulate the expression and trafficking of Cu ATPases in malignant cells are far from being completely understood. This review summarizes current data on the role of ATP7A/B in the regulation of Cu and Pt metabolism in malignant cells and outlines questions and challenges that should be addressed to understand how ATP7A and ATP7B trafficking mechanisms might be targeted to counteract tumor development.

scholarly journals Genetic analysis of Saccharomyces cerevisiae chromosome I: on the role of mutagen specificity in delimiting the set of genes identifiable using temperature-sensitive-lethal mutations.

Genetics ◽  
1991 ◽  
Vol 127 (2) ◽  
pp. 279-285 ◽  
Author(s):  
S D Harris ◽  
J R Pringle
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Essential Genes ◽  
Previous Attempt ◽  
Temperature Sensitive ◽  
Molecular Analyses ◽  
Cellular Processes ◽  
Lethal Mutations ◽  
Mutagen Specificity ◽  
Complementation Groups ◽  
Chromosome I

Abstract In a previous attempt to identify as many as possible of the essential genes on Saccharomyces cerevisiae chromosome I, temperature-sensitive (Ts-) lethal mutations that had been induced by ethyl methane-sulfonate or nitrosoguanidine were analyzed. Thirty-two independently isolated mutations that mapped to chromosome I identified only three complementation groups, all of which had been known previously. In contrast, molecular analyses of segments of the chromosome have suggested the presence of numerous additional essential genes. In order to assess the degree to which problems of mutagen specificity had limited the set of genes detected using Ts- lethal mutations, we isolated a new set of such mutations after mutagenesis with UV or nitrogen mustard. Surprisingly, of 21 independently isolated mutations that mapped to chromosome I, 17 were again in the same three complementation groups as identified previously, and two of the remaining four mutations were apparently in a known gene involved in cysteine biosynthesis. Of the remaining two mutations, one was in one of the essential genes identified in the molecular analyses, and the other was too leaky to be mapped. These results suggest that only a minority of the essential genes in yeast can be identified using Ts- lethal mutations, regardless of the mutagen used, and thus emphasize the need to use multiple genetic strategies in the investigation of cellular processes.

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