PTEN and myotubularin phosphatases: from 3-phosphoinositide dephosphorylation to disease

Wishart, Matthew J.; Dixon, Jack E.

doi:10.1016/s0962-8924(02)02412-1

Cited by 173 publications

(117 citation statements)

References 41 publications

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“…PI-3K products function as ligands for protein targeting modules (pleckstrin homology (PH) and PX domains) [92]. Signaling proteins with PH domains accumulate at PI-3K activation sites by directly binding to PI(3,4)P2 and PI (3,4,5)P3 [14,36].…”

Section: Roles For Polyphosphoinositides In Regulated Releasementioning

confidence: 99%

A new approach to the molecular analysis of docking, priming, and regulated membrane fusion

Rogasevskaia

Coorssen

2011

J Chem Biol

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Studies using isolated sea urchin cortical vesicles have proven invaluable in dissecting mechanisms of Ca 2+ -triggered membrane fusion. However, only acute molecular manipulations are possible in vitro. Here, using selective pharmacological manipulations of sea urchin eggs ex vivo, we test the hypothesis that specific lipidic components of the membrane matrix selectively affect defined late stages of exocytosis, particularly the Ca 2+ -triggered steps of fast membrane fusion. Egg treatments with cholesterol-lowering drugs resulted in the inhibition of vesicle fusion. Exogenous cholesterol recovered fusion extent and efficiency in cholesterol-depleted membranes; α-tocopherol, a structurally dissimilar curvature analogue, selectively restored fusion extent. Inhibition of phospholipase C reduced vesicle phosphatidylethanolamine and suppressed both the extent and kinetics of fusion. Although phosphatidylinositol-3-kinase inhibition altered levels of polyphosphoinositide species and reduced all fusion parameters, sequestering polyphosphoinositides selectively inhibited fusion kinetics. Thus, cholesterol and phosphatidylethanolamine play direct roles in the fusion pathway, contributing negative curvature. Cholesterol also organizes the physiological fusion site, defining fusion efficiency. A selective influence of phosphatidylethanolamine on fusion kinetics sheds light on the local microdomain structure at the site of docking/fusion. Polyphosphoinositides have modulatory upstream roles in priming: alterations in specific polyphosphoinositides likely represent the terminal priming steps defining fully docked, release-ready vesicles. Thus, this pharmacological approach has the potential to be a robust high-throughput platform to identify molecular components of the physiological fusion machine critical to docking, priming, and triggered fusion.

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Section: Roles For Polyphosphoinositides In Regulated Releasementioning

confidence: 99%

A new approach to the molecular analysis of docking, priming, and regulated membrane fusion

Rogasevskaia

Coorssen

2011

J Chem Biol

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“…Although experimental scrutiny of the phospholipases has historically been more intense, recent demonstrations of the significant biological functions played by PTEN, the myotubularins, and synaptojanins highlight the general importance of PIP phosphatases (Wishart et al, 2001;Wishart and Dixon, 2002;Wenk and De Camilli, 2004).…”

Section: Introductionmentioning

confidence: 99%

“…Spatial and temporal control of such reactions requires a finely coordinated balance between the activities of the lipid kinases that produce PIPs and the activities of enzymes that degrade them. PIP turnover is catalyzed by two general classes of enzymes: phospholipases and PIP phosphatases.Although experimental scrutiny of the phospholipases has historically been more intense, recent demonstrations of the significant biological functions played by PTEN, the myotubularins, and synaptojanins highlight the general importance of PIP phosphatases (Wishart et al, 2001;Wishart and Dixon, 2002;Wenk and De Camilli, 2004).The SAC domain derives from the yeast Sac1 protein (ySac1; Cleves et al, 1989), and it represents a signature for PIP phosphatase catalytic activity . PIP phosphatases such as phosphatase and tensin homolog (mutated in multiple advanced cancers 1) (PTEN) (Maehama et al, 2001), synaptojanins (Cremona et al, 1999), and synaptojanin-like proteins (Srinivasan et al, 1997;Stolz et al, 1998) all harbor SAC domains.…”

mentioning

confidence: 99%

The Sac1 Phosphoinositide Phosphatase Regulates Golgi Membrane Morphology and Mitotic Spindle Organization in Mammals

Liu

Boukhelifa

Tribble

et al. 2008

MBoC

131

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Phosphoinositides (PIPs) are ubiquitous regulators of signal transduction events in eukaryotic cells. PIPs are degraded by various enzymes, including PIP phosphatases. The integral membrane Sac1 phosphatases represent a major class of such enzymes. The central role of lipid phosphatases in regulating PIP homeostasis notwithstanding, the biological functions of Sac1-phosphatases remain poorly characterized. Herein, we demonstrate that functional ablation of the single murine Sac1 results in preimplantation lethality in the mouse and that Sac1 insufficiencies result in disorganization of mammalian Golgi membranes and mitotic defects characterized by multiple mechanically active spindles. Complementation experiments demonstrate mutant mammalian Sac1 proteins individually defective in either phosphoinositide phosphatase activity, or in recycling of the enzyme from the Golgi system back to the endoplasmic reticulum, are nonfunctional proteins in vivo. The data indicate Sac1 executes an essential household function in mammals that involves organization of both Golgi membranes and mitotic spindles and that both enzymatic activity and endoplasmic reticulum localization are important Sac1 functional properties. INTRODUCTIONSpatial and temporal regulation of intracellular signaling in eukaryotic cells involves the compartmentalization of membrane surfaces into discrete, albeit often transient, functional units. There are several biochemical strategies by which cells generate such units or domains. One well-established strategy uses the chemical diversity offered by phosphoinositides (PIPs), i.e., phosphorylated forms of phosphatidylinositol (PtdIns) (Majerus, 1997;Fruman et al., 1998;Strahl and Thorner, 2007). The chemical heterogeneity of individual PIP species permits the construction of chemically unique platforms on membrane surfaces that, in turn, recruit unique cohorts of proteins that drive specific biological reactions. Spatial and temporal control of such reactions requires a finely coordinated balance between the activities of the lipid kinases that produce PIPs and the activities of enzymes that degrade them. PIP turnover is catalyzed by two general classes of enzymes: phospholipases and PIP phosphatases.Although experimental scrutiny of the phospholipases has historically been more intense, recent demonstrations of the significant biological functions played by PTEN, the myotubularins, and synaptojanins highlight the general importance of PIP phosphatases (Wishart et al., 2001;Wishart and Dixon, 2002;Wenk and De Camilli, 2004).The SAC domain derives from the yeast Sac1 protein (ySac1; Cleves et al., 1989), and it represents a signature for PIP phosphatase catalytic activity . PIP phosphatases such as phosphatase and tensin homolog (mutated in multiple advanced cancers 1) (PTEN) (Maehama et al., 2001), synaptojanins (Cremona et al., 1999), and synaptojanin-like proteins (Srinivasan et al., 1997;Stolz et al., 1998) all harbor SAC domains. The prototypical member of this family, ySac1, catalyzes the dephosphoryla...

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“…In particular, phosphatase and tensin homologue deleted on chromosome 10 (PTEN), which is a lipid phosphatase with specificity for the 3 position of PI(3,4,5)P 3 (Wishart and Dixon, 2002), is down-regulated by constitutive signaling by Notch1 in T cell acute lymphoblastic leukemias (Sulis et al, 2008). There is also evidence for microRNAmediated suppression of PTEN in lymphoma.…”

mentioning

confidence: 99%

Phosphoinositide-dependent kinase 1 controls migration and malignant transformation but not cell growth and proliferation in PTEN-null lymphocytes

Finlay¹,

Sinclair²,

Feijóo³

et al. 2009

J Cell Biol

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PTEN and myotubularin phosphatases: from 3-phosphoinositide dephosphorylation to disease

Cited by 173 publications

References 41 publications

A new approach to the molecular analysis of docking, priming, and regulated membrane fusion

A new approach to the molecular analysis of docking, priming, and regulated membrane fusion

The Sac1 Phosphoinositide Phosphatase Regulates Golgi Membrane Morphology and Mitotic Spindle Organization in Mammals

Phosphoinositide-dependent kinase 1 controls migration and malignant transformation but not cell growth and proliferation in PTEN-null lymphocytes

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