A method to control phosphoinositides and to analyze PTEN function in living cells using voltage sensitive phosphatases

Mavrantoni, Angeliki; Thallmair, Veronika; Leitner, Michael G.; Schreiber, Daniela; Oliver, Dominik; Halaszovich, Christian R.

doi:10.3389/fphar.2015.00068

Cited by 19 publications

(18 citation statements)

References 58 publications

(94 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Here, we investigated the inhibition of PTEN activity by bisperoxovanadium (bpV) in post renal fibrosis induced by AKI with ischemia reperfusion (IR) models in mice. BpV compounds are dual protein-lipid phosphatases best known for their potent and specific inhibition of PTEN, which usually has been characterized using in vitro phosphatase assays and Western blot analyses of the phosphorylation of Akt, a downstream target of the PTEN pathway [17]. Our results demonstrated that inhibition of PTEN activity exacerbated the development of post renal fibrosis induced by AKI.…”

Section: Introductionmentioning

confidence: 49%

Inhibition of PTEN Activity Aggravates Post Renal Fibrosis in Mice with Ischemia Reperfusion-Induced Acute Kidney Injury

Zhou

Zhong

Shi

et al. 2017

Cell Physiol Biochem

View full text Add to dashboard Cite

Background: Renal fibrosis is a common pathophysiological feature of chronic kidney disease. Acute kidney injury (AKI) is defined as an independent causal factor of chronic kidney disease, with a pathological representation of post renal fibrosis. However, the etiopathogenesis underlying post renal fibrosis induced by AKI is not completely understood. Methods: BALB/c mice were treated with bpv or vehicle controls and were, respectively, the ischemia reperfusion (IR) model group and control group. All of the animals had blood taken from the orbital venous plexus at 24 hours after IR. Six mice in each group were randomly chosen and euthanized 7 days after IR treatment, and the remaining six mice in each group were euthanized 14 days after IR treatment. We examined the effect on post kidney fibrosis of inhibiting PTEN activity in mice in an IR induced AKI experimental model. Results: Compared with vehicle mice, bpv-(PTEN specific inhibitor) treated mice accumulated more bone marrow-derived fibroblasts and myofibroblasts in the kidneys. Inhibition of PTEN activity increased the expression of α-smooth muscle actin and extracellular matrix proteins and post kidney fibrosis. Furthermore, inhibition of PTEN activity resulted in more inflammatory cytokines in the kidneys of mice subjected to IR-induced renal fibrosis. Moreover, inhibition of PTEN activity up-regulated PI3K protein expression and Akt phosphorylation. Conclusions: Our study demonstrated that PTEN played an important role in post renal fibrosis in mice with ischemia reperfusion-induced AKI. These results indicated that the PTEN/PI3K/Akt signaling pathway may serve as a novel therapeutic target for AKI-induced chronic kidney disease.

show abstract

Section: Introductionmentioning

confidence: 49%

Inhibition of PTEN Activity Aggravates Post Renal Fibrosis in Mice with Ischemia Reperfusion-Induced Acute Kidney Injury

Zhou

Zhong

Shi

et al. 2017

Cell Physiol Biochem

View full text Add to dashboard Cite

show abstract

“…To test if zinc inhibits ciVSP itself, we used an optical method of measuring ciVSP activity in which we coexpressed the enzyme in CHO cells together with KCNQ4 and the optical PIP 2 reporter PLC-δPH-GFP (44) and measured its translocation from membrane to cytosol in response to depolarization by an extracellular solution containing 150 mM KCl instead of NaCl (45). The intracellular K + concentration in CHO cells is ∼140 mM (46); thus such a maneuver depolarized the membrane potential to approximately +2 mV, which is sufficient to trigger measurable ciVSP activation (43,45).…”

Section: +mentioning

confidence: 99%

“…The intracellular K + concentration in CHO cells is ∼140 mM (46); thus such a maneuver depolarized the membrane potential to approximately +2 mV, which is sufficient to trigger measurable ciVSP activation (43,45). Accordingly, confocal imaging of the plasma membrane PIP 2 labeled by PLC-δPH-GFP revealed clear and reversible depolarization-induced PIP 2 depletion manifested in PLC-δPH-GFP translocation and an increase in cytosolic fluorescence .…”

Section: +mentioning

confidence: 99%

Intracellular zinc activates KCNQ channels by reducing their dependence on phosphatidylinositol 4,5-bisphosphate

Gao

Boillat

Huang

et al. 2017

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

View full text Add to dashboard Cite

M-type (Kv7, KCNQ) potassium channels are proteins that control the excitability of neurons and muscle cells. Many physiological and pathological mechanisms of excitation operate via the suppression of M channel activity or expression. Conversely, pharmacological augmentation of M channel activity is a recognized strategy for the treatment of hyperexcitability disorders such as pain and epilepsy. However, physiological mechanisms resulting in M channel potentiation are rare. Here we report that intracellular free zinc directly and reversibly augments the activity of recombinant and native M channels. This effect is mechanistically distinct from the known redoxdependent KCNQ channel potentiation. Interestingly, the effect of zinc cannot be attributed to a single histidine-or cysteine-containing zinc-binding site within KCNQ channels. Instead, zinc dramatically reduces KCNQ channel dependence on its obligatory physiological activator, phosphatidylinositol 4,5-bisphosphate (PIP 2 ). We hypothesize that zinc facilitates interactions of the lipid-facing interface of a KCNQ protein with the inner leaflet of the plasma membrane in a way similar to that promoted by PIP 2 . Because zinc is increasingly recognized as a ubiquitous intracellular second messenger, this discovery might represent a hitherto unknown native pathway of M channel modulation and provide a fresh strategy for the design of M channel activators for therapeutic purposes.+ channels are a family of voltagegated K + channels with a very distinctive and robust role in the control of cellular excitability. The channels give rise to noninactivating K + currents with slow kinetics and a very negative activation threshold (−60 mV or even more negative). In combination, these features allow KCNQ channels to remain partially active at voltages near the resting membrane potential of a neuron or a muscle cell and thus strongly influence excitability (1, 2). Transient KCNQ channel inhibition leads to reversible increases in neuronal excitability, whereas long-term losses of KCNQ channel activity often result in debilitating excitability disorders (1, 2). Thus, loss-of-function mutations within KCNQ genes underlie some types of epilepsy, deafness, and arrhythmias, whereas transcriptional down-regulation in sensory nerves may result in chronic pain (2). Conversely, M channel enhancers ("openers") reduce excitability and are clinically used as antiepileptic drugs (e.g., retigabine) or analgesics (e.g., flupirtine) (3). The therapeutic utility of KCNQ channel openers extends to other disorders linked to deregulated excitability, such as anxiety, stroke, and smooth muscle disorders (2, 3); therefore a global quest for specific and selective KCNQ openers is currently underway (3).The KCNQ channel family contains five members, KCNQ1-5 (Kv7.1-Kv7.5). KCNQ1 is expressed mostly within the cardiovascular system, whereas the other members are predominantly neuronal (1, 2). The most abundant M-type channel within the nervous system is believed to be the heteromeric KCNQ2/3 chan...

show abstract

“…Considering that PIPKI isoforms may be highly activated during egg fertilization (44-47), we could envision why previous studies found PI(4,5)P 2 increases following the rapid membrane depolarization (42) during fertilization (48)(49)(50)(51). Taken together, VSPs possibly regulate the spatial and temporal distribution of phosphoinositides in a cell membrane in response to voltage (52) or pH changes in the cell (7,53). If the distribution is localized and dynamic, VSPs may determine binding of target proteins at specific regions and time, resulting in, for example, cell migration or polarization (54)(55)(56).…”

Section: Discussionmentioning

confidence: 96%

Phosphoinositide 5- and 3-phosphatase activities of a voltage-sensing phosphatase in living cells show identical voltage dependence

Keum

Kruse

Kim

et al. 2016

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

View full text Add to dashboard Cite

Voltage-sensing phosphatases (VSPs) are homologs of phosphatase and tensin homolog (PTEN), a phosphatidylinositol 3,4-bisphosphate [PI(3,4)P2] and phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3] 3-phosphatase. However, VSPs have a wider range of substrates, cleaving 3-phosphate from PI(3,4)P2 and probably PI(3,4,5)P3 as well as 5-phosphate from phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] and PI(3,4,5)P3 in response to membrane depolarization. Recent proposals say these reactions have differing voltage dependence. Using Förster resonance energy transfer probes specific for different PIs in living cells with zebrafish VSP, we quantitate both voltage-dependent 5- and 3-phosphatase subreactions against endogenous substrates. These activities become apparent with different voltage thresholds, voltage sensitivities, and catalytic rates. As an analytical tool, we refine a kinetic model that includes the endogenous pools of phosphoinositides, endogenous phosphatase and kinase reactions connecting them, and four exogenous voltage-dependent 5- and 3-phosphatase subreactions of VSP. We show that apparent voltage threshold differences for seeing effects of the 5- and 3-phosphatase activities in cells are not due to different intrinsic voltage dependence of these reactions. Rather, the reactions have a common voltage dependence, and apparent differences arise only because each VSP subreaction has a different absolute catalytic rate that begins to surpass the respective endogenous enzyme activities at different voltages. For zebrafish VSP, our modeling revealed that 3-phosphatase activity against PI(3,4,5)P3 is 55-fold slower than 5-phosphatase activity against PI(4,5)P2; thus, PI(4,5)P2 generated more slowly from dephosphorylating PI(3,4,5)P3 might never accumulate. When 5-phosphatase activity was counteracted by coexpression of a phosphatidylinositol 4-phosphate 5-kinase, there was accumulation of PI(4,5)P2 in parallel to PI(3,4,5)P3 dephosphorylation, emphasizing that VSPs can cleave the 3-phosphate of PI(3,4,5)P3.

show abstract

A method to control phosphoinositides and to analyze PTEN function in living cells using voltage sensitive phosphatases

Cited by 19 publications

References 58 publications

Inhibition of PTEN Activity Aggravates Post Renal Fibrosis in Mice with Ischemia Reperfusion-Induced Acute Kidney Injury

Inhibition of PTEN Activity Aggravates Post Renal Fibrosis in Mice with Ischemia Reperfusion-Induced Acute Kidney Injury

Intracellular zinc activates KCNQ channels by reducing their dependence on phosphatidylinositol 4,5-bisphosphate

Phosphoinositide 5- and 3-phosphatase activities of a voltage-sensing phosphatase in living cells show identical voltage dependence

Contact Info

Product

Resources

About