Gene expression profile of Ci-VSP in juveniles and adult blood cells of ascidian

Ogasawara, Michio; Sasaki, Mari; Nakazawa, Noriko; Nishino, Atsuo; Okamura, Yasushi

doi:10.1016/j.gep.2010.12.004

Cited by 21 publications

(34 citation statements)

References 28 publications

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“…VSP/TPTE is expressed in testis of ascidian, chick, mouse, and human. VSP is also expressed in blood cells, the nervous system, and epithelium of the developing intestine of ascidian (29) and in the epithelium of chick kidney (16). Patterns of membrane-potential changes may lead to alteration of cell morphology in these VSP-expressing cells, and the bidirectionality of the regulation of PI(3,4)P 2 levels may be important for fine-tuning cell morphology that depends on membrane potential.…”

Section: Discussionmentioning

confidence: 99%

3′ Phosphatase activity toward phosphatidylinositol 3,4-bisphosphate [PI(3,4)P ₂ ] by voltage-sensing phosphatase (VSP)

Kurokawa

Takasuga

Sakata

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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Voltage-sensing phosphatases (VSPs) consist of a voltage-sensor domain and a cytoplasmic region with remarkable sequence similarity to phosphatase and tensin homolog deleted on chromosome 10 (PTEN), a tumor suppressor phosphatase. VSPs dephosphorylate the 5′ position of the inositol ring of both phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P 3 ] and phosphatidylinositol 4,5-bisphosphate [PI (4,5)P 2 ] upon voltage depolarization. However, it is unclear whether VSPs also have 3′ phosphatase activity. To gain insights into this question, we performed in vitro assays of phosphatase activities of Ciona intestinalis VSP (Ci-VSP) and transmembrane phosphatase with tensin homology (TPTE) and PTEN homologous inositol lipid phosphatase (TPIP; one human ortholog of VSP) with radiolabeled PI(3,4,5)P 3 . TLC assay showed that the 3′ phosphate of PI(3,4,5)P 3 was not dephosphorylated, whereas that of phosphatidylinositol 3,4-bisphosphate [PI(3,4)P 2 ] was removed by VSPs. Monitoring of PI(3,4)P 2 levels with the pleckstrin homology (PH) domain from tandem PH domaincontaining protein (TAPP1) fused with GFP (PH TAPP1 -GFP) by confocal microscopy in amphibian oocytes showed an increase of fluorescence intensity during depolarization to 0 mV, consistent with 5′ phosphatase activity of VSP toward PI(3,4,5)P 3 . However, depolarization to 60 mV showed a transient increase of GFP fluorescence followed by a decrease, indicating that, after PI(3,4,5)P 3 is dephosphorylated at the 5′ position, PI(3,4)P 2 is then dephosphorylated at the 3′ position. These results suggest that substrate specificity of the VSP changes with membrane potential.phosphoinositide | ascidian P hosphoinositides serve as not only components of biological membranes, but also as coordinators of diverse cellular events including proliferation, cell migration, vesicle turnover, and ion transport. Numerous phosphatases and kinases that regulate phosphoinositide availability have been identified (1, 2), and defects or enhancements of these enzymes lead to tumorigenesis, metabolic disorders, and degeneration. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a wellcharacterized phosphatase that dephosphorylates phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P 3 ] (3). Defect or loss of PTEN leads to generation or progression of tumors (4, 5), and enhancement of PTEN underlies diabetes (6). We have shown that a sea squirt ortholog of one PTEN-related phosphatase, transmembrane phosphatase with tensin homology (TPTE)/ TPTE and PTEN homologous inositol lipid phosphatase (TPIP), designated as Ciona intestinalis VSP (Ci-VSP), dephosphorylates phosphoinositides that depend on membrane potential (7, 8). Ci-VSP has a voltage-sensor domain (VSD) consisting of four transmembrane segments and a PTEN-like region. Despite its sequence similarity to PTEN in its active center, Ci-VSP exhibits 5′ phosphatase activity toward PI(3,4,5)P 3 and phosphatidylinositol 4,5-bisphosphate [PI(4,5)P 2 ], unlike PTEN. Such distinct substrate specificity from PTEN partly d...

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Section: Discussionmentioning

confidence: 99%

3′ Phosphatase activity toward phosphatidylinositol 3,4-bisphosphate [PI(3,4)P ₂ ] by voltage-sensing phosphatase (VSP)

Kurokawa

Takasuga

Sakata

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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“…Consequently, VSPs may serve cell type-specifi c functions rather than mediating general cellular mechanisms. However, expression may be more widespread during development ( 28 ), as observed for the nonvertebrate Ci-VSP ( 29 ) and the homolog in birds ( 30 ).…”

Section: Functional Role Of Hvsp1mentioning

confidence: 93%

A human phospholipid phosphatase activated by a transmembrane control module

Halaszovich

Leitner

Mavrantoni

et al. 2012

Journal of Lipid Research

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This article is available online at http://www.jlr.org domain (VSD) homologous to the voltage sensors of voltage-gated ion channels and an intracellular C-terminal catalytic domain (CD) with high similarity to the tumor suppressor lipid phosphatase, PTEN ( Fig.1A ) ( 1 ). The enzymatic activity of the CD is controlled by the VSD via an intramolecular conformational switch ( 4, 5 ). At typical negative resting voltages, the CD is inactive and is rapidly activated at more-positive (depolarized) voltages. The VSP homologs characterized to date are phosphoinositide 5-phosphatases that degrade the major signaling phospholi pids PI(4,5)P 2 and PI(3,4,5)P 3 ( 2 ). Both phosphoinositides have key signaling roles in many cellular processes, including cell proliferation and differentiation, cytoskeletal dynamics, membrane traffi cking, and control of ion channels ( 6, 7 ). Although little is known to date about the biological functions of VSPs, the ubiquitous roles of phosphoinositides and of electrical signaling suggest a potential impact on a large spectrum of cellular processes.The principle of operation of VSPs was initially demonstrated for Ci-VSP, the prototypic VSP from the invertebrate chordate Ciona intestinalis . Subsequently, functional vertebrate VSPs have been identifi ed in fi shes and amphibia ( 8, 9 ). The VSP gene is also conserved in mammals ( 10 ). In general, there appears to be one VSP homolog in mammalian genomes; in the human genome, however, there are two expressed homologs, TPTE and TPTE2 (also termed TPIP) and additional pseudo-genes ( 10, 11 ). TPTE conforms to the architecture of VSPs, but it lacks phosphatase activity due to amino acid exchanges in the catalytic CX 5 R motif in the P-loop of the phosphatase domain The recent discovery of voltage-sensitive phosphatases (VSPs) ( 1 ) established a novel molecular principle of electrochemical coupling: VSPs directly mediate the degradation of phosphoinositides in response to depolarization of the membrane potential ( 2, 3 ). These so-far-unique electro-enzymes consist of a transmembrane voltage sensor

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“…The voltage-sensing phosphatase (VSP) 3 was discovered through the survey of the genome of the ascidian, Ciona intestinalis, as a hybrid protein that has a voltage sensor domain (VSD) consisting of four ␣-helices (S1-S4) for voltage sensing and a cytoplasmic region encoding a phosphatidylinositol phosphatase domain (1). The VSP gene is conserved from sea urchins to humans where it is expressed in the testis (2).…”

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confidence: 99%

“…The VSP gene is conserved from sea urchins to humans where it is expressed in the testis (2). In the recent report, C. intestinalis VSP (Ci-VSP) is expressed in the cells of the stomach, intestine, and blood of juveniles detected by whole mount in situ hybridization (3). The VSD of VSP bears homology to the VSD of voltage-gated ion channels and a recently identified voltage-gated proton channel protein that contains only the VSD without pore domain, VSOP or Hv1 (4,5).…”

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Crystal Structure of the Cytoplasmic Phosphatase and Tensin Homolog (PTEN)-like Region of Ciona intestinalis Voltage-sensing Phosphatase Provides Insight into Substrate Specificity and Redox Regulation of the Phosphoinositide Phosphatase Activity

Matsuda

Takeshita

Kurokawa

et al. 2011

Journal of Biological Chemistry

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Ciona intestinalis voltage-sensing phosphatase (Ci-VSP) has a transmembrane voltage sensor domain and a cytoplasmic region sharing similarity to the phosphatase and tensin homolog (PTEN). It dephosphorylates phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate upon membrane depolarization. The cytoplasmic region is composed of a phosphatase domain and a putative membrane interaction domain, C2. Here we determined the crystal structures of the Ci-VSP cytoplasmic region in three distinct constructs, wildtype (248 -576), wild-type (236 -576), and G365A mutant (248 -576). The crystal structure of WT-236 and G365A-248 had the disulfide bond between the catalytic residue Cys-363 and the adjacent residue Cys-310. On the other hand, the disulfide bond was not present in the crystal structure of WT-248. These suggest the possibility that Ci-VSP is regulated by reactive oxygen species as found in PTEN. These structures also revealed that the conformation of the TI loop in the active site of the Ci-VSP cytoplasmic region was distinct from the corresponding region of PTEN; Ci-VSP has glutamic acid (Glu-411) in the TI loop, orienting toward the center of active site pocket. Mutation of Glu-411 led to acquirement of increased activity toward phosphatidylinositol 3,5-bisphosphate, suggesting that this site is required for determining substrate specificity. Our results provide the basic information of the enzymatic mechanism of Ci-VSP.The voltage-sensing phosphatase (VSP) 3 was discovered through the survey of the genome of the ascidian, Ciona intestinalis, as a hybrid protein that has a voltage sensor domain (VSD) consisting of four ␣-helices (S1-S4) for voltage sensing and a cytoplasmic region encoding a phosphatidylinositol phosphatase domain (1). The VSP gene is conserved from sea urchins to humans where it is expressed in the testis (2). In the recent report, C. intestinalis VSP (Ci-VSP) is expressed in the cells of the stomach, intestine, and blood of juveniles detected by whole mount in situ hybridization (3). The VSD of VSP bears homology to the VSD of voltage-gated ion channels and a recently identified voltage-gated proton channel protein that contains only the VSD without pore domain, VSOP or Hv1 (4, 5). The Ci-VSP cytoplasmic region, which consists of a phosphatase domain (PD) and a C2 domain, shares high sequence similarity with the phosphatase and tensin homolog (PTEN) (1, 6). The amino acid sequence of the Ci-VSP cytoplasmic region has similarity to that of PTEN with 36% identity. A unique feature of both invertebrate and vertebrate VSPs is that depolarization induces phosphoinositide phosphatase activity through coupling of VSD to the phosphatase region (7-9). The enzymatic activity of Ci-VSP increases in the range of membrane potentials, from Ϫ80 to 100 mV, correlating with the extent of voltage sensor movement (7-8). Ci-VSP most likely operates as a monomer as shown by a study of single molecule imaging in heterologous expression system (10). The linker region between the VSD and ...

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Gene expression profile of Ci-VSP in juveniles and adult blood cells of ascidian

Cited by 21 publications

References 28 publications

3′ Phosphatase activity toward phosphatidylinositol 3,4-bisphosphate [PI(3,4)P ₂ ] by voltage-sensing phosphatase (VSP)

3′ Phosphatase activity toward phosphatidylinositol 3,4-bisphosphate [PI(3,4)P ₂ ] by voltage-sensing phosphatase (VSP)

A human phospholipid phosphatase activated by a transmembrane control module

Crystal Structure of the Cytoplasmic Phosphatase and Tensin Homolog (PTEN)-like Region of Ciona intestinalis Voltage-sensing Phosphatase Provides Insight into Substrate Specificity and Redox Regulation of the Phosphoinositide Phosphatase Activity

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Gene expression profile of Ci-VSP in juveniles and adult blood cells of ascidian

Cited by 21 publications

References 28 publications

3′ Phosphatase activity toward phosphatidylinositol 3,4-bisphosphate [PI(3,4)P 2 ] by voltage-sensing phosphatase (VSP)

3′ Phosphatase activity toward phosphatidylinositol 3,4-bisphosphate [PI(3,4)P 2 ] by voltage-sensing phosphatase (VSP)

A human phospholipid phosphatase activated by a transmembrane control module

Crystal Structure of the Cytoplasmic Phosphatase and Tensin Homolog (PTEN)-like Region of Ciona intestinalis Voltage-sensing Phosphatase Provides Insight into Substrate Specificity and Redox Regulation of the Phosphoinositide Phosphatase Activity

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3′ Phosphatase activity toward phosphatidylinositol 3,4-bisphosphate [PI(3,4)P ₂ ] by voltage-sensing phosphatase (VSP)

3′ Phosphatase activity toward phosphatidylinositol 3,4-bisphosphate [PI(3,4)P ₂ ] by voltage-sensing phosphatase (VSP)