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Sang Y, Niu C, Xu J, Zhu T, You S, Wang J, Zhang L, Du X, Zhang H. PI4KIIIβ-Mediated Phosphoinositides Metabolism Regulates Function of the VTA Dopaminergic Neurons and Depression-Like Behavior. J Neurosci 2024; 44:e0555232024. [PMID: 38267258 PMCID: PMC10941068 DOI: 10.1523/jneurosci.0555-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 12/18/2023] [Accepted: 01/11/2024] [Indexed: 01/26/2024] Open
Abstract
Phosphoinositides, including phosphatidylinositol-4,5-bisphosphate (PIP2), play a crucial role in controlling key cellular functions such as membrane and vesicle trafficking, ion channel, and transporter activity. Phosphatidylinositol 4-kinases (PI4K) are essential enzymes in regulating the turnover of phosphoinositides. However, the functional role of PI4Ks and mediated phosphoinositide metabolism in the central nervous system has not been fully revealed. In this study, we demonstrated that PI4KIIIβ, one of the four members of PI4Ks, is an important regulator of VTA dopaminergic neuronal activity and related depression-like behavior of mice by controlling phosphoinositide turnover. Our findings provide new insights into possible mechanisms and potential drug targets for neuropsychiatric diseases, including depression. Both sexes were studied in basic behavior tests, but only male mice could be used in the social defeat depression model.
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Affiliation(s)
- Yuqi Sang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- Collaborative Innovation Center of Hebei Province for Mechanism, Diagnosis and Treatment of Neuropsychiatric Diseases, Hebei Medical University, Shijiazhuang, Hebei 050011, China
| | - Chenxu Niu
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- Collaborative Innovation Center of Hebei Province for Mechanism, Diagnosis and Treatment of Neuropsychiatric Diseases, Hebei Medical University, Shijiazhuang, Hebei 050011, China
| | - Jiaxi Xu
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University Health Science Center, Xi'an, Shanxi 710061, China
| | - Tiantian Zhu
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- Collaborative Innovation Center of Hebei Province for Mechanism, Diagnosis and Treatment of Neuropsychiatric Diseases, Hebei Medical University, Shijiazhuang, Hebei 050011, China
| | - Shuangzhu You
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- Collaborative Innovation Center of Hebei Province for Mechanism, Diagnosis and Treatment of Neuropsychiatric Diseases, Hebei Medical University, Shijiazhuang, Hebei 050011, China
| | - Jing Wang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- Collaborative Innovation Center of Hebei Province for Mechanism, Diagnosis and Treatment of Neuropsychiatric Diseases, Hebei Medical University, Shijiazhuang, Hebei 050011, China
| | - Ludi Zhang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- Collaborative Innovation Center of Hebei Province for Mechanism, Diagnosis and Treatment of Neuropsychiatric Diseases, Hebei Medical University, Shijiazhuang, Hebei 050011, China
| | - Xiaona Du
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- Collaborative Innovation Center of Hebei Province for Mechanism, Diagnosis and Treatment of Neuropsychiatric Diseases, Hebei Medical University, Shijiazhuang, Hebei 050011, China
| | - Hailin Zhang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- Collaborative Innovation Center of Hebei Province for Mechanism, Diagnosis and Treatment of Neuropsychiatric Diseases, Hebei Medical University, Shijiazhuang, Hebei 050011, China
- Department of Psychiatry, The First Hospital of Hebei Medical University, Mental Health Institute of Hebei Medical University, Shijiazhuang, Hebei 050000, China
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Wu H, Sun Q, Yuan S, Wang J, Li F, Gao H, Chen X, Yang R, Xu J. AT1 Receptors: Their Actions from Hypertension to Cognitive Impairment. Cardiovasc Toxicol 2022; 22:311-325. [PMID: 35211833 PMCID: PMC8868040 DOI: 10.1007/s12012-022-09730-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Accepted: 02/07/2022] [Indexed: 12/18/2022]
Abstract
Hypertension is one of the most prevalent cardiovascular disorders worldwide, affecting 1.13 billion people, or 14% of the global population. Hypertension is the single biggest risk factor for cerebrovascular dysfunction. According to the American Heart Association, high blood pressure (BP), especially in middle-aged individuals (~ 40 to 60 years old), is associated with an increased risk of dementia, later in life. Alzheimer’s disease and cerebrovascular disease are the two leading causes of dementia, accounting for around 80% of the total cases and usually combining mixed pathologies from both. Little is known regarding how hypertension affects cognitive function, so the impact of its treatment on cognitive impairment has been difficult to assess. The brain renin-angiotensin system (RAS) is essential for BP regulation and overactivity of this system has been established to precede the development and maintenance of hypertension. Angiotensin II (Ang-II), the main peptide within this system, induces vasoconstriction and impairs neuro-vascular coupling by acting on brain Ang-II type 1 receptors (AT1R). In this review, we systemically analyzed the association between RAS and biological mechanisms of cognitive impairment, from the perspective of AT1R located in the central nervous system. Additionally, the possible contribution of brain AT1R to global cognition decline in COVID-19 cases will be discussed as well.
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Affiliation(s)
- Hanxue Wu
- Department of Physiology and Pathophysiology, School of Medicine, Xi'an Jiaotong University, 76 West Yanta Road, Xi'an, 710061, China
| | - Qi Sun
- The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, China
| | - Shenglan Yuan
- Department of Physiology and Pathophysiology, School of Medicine, Xi'an Jiaotong University, 76 West Yanta Road, Xi'an, 710061, China
| | - Jiawei Wang
- Department of Physiology and Pathophysiology, School of Medicine, Xi'an Jiaotong University, 76 West Yanta Road, Xi'an, 710061, China
| | - Fanni Li
- The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, 710061, China
| | - Hongli Gao
- Department of Physiology and Pathophysiology, School of Medicine, Xi'an Jiaotong University, 76 West Yanta Road, Xi'an, 710061, China
| | - Xingjuan Chen
- Institute of Medical Research, Northwestern Polytechnical University, Xi'an, 710072, China
| | - Rui Yang
- Department of Physiology and Pathophysiology, School of Medicine, Xi'an Jiaotong University, 76 West Yanta Road, Xi'an, 710061, China
| | - Jiaxi Xu
- Department of Physiology and Pathophysiology, School of Medicine, Xi'an Jiaotong University, 76 West Yanta Road, Xi'an, 710061, China.
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Membrane pools of phosphatidylinositol-4-phosphate regulate KCNQ1/KCNE1 membrane expression. Commun Biol 2021; 4:1392. [PMID: 34907346 PMCID: PMC8671492 DOI: 10.1038/s42003-021-02909-1] [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: 07/23/2020] [Accepted: 11/24/2021] [Indexed: 11/23/2022] Open
Abstract
Plasma membrane phosphatidylinositol 4-phosphate (PI4P) is a precursor of PI(4,5)P2, an important regulator of a large number of ion channels. Although the role of the phospholipid PI(4,5)P2 in stabilizing ion channel function is well established, little is known about the role of phospholipids in channel membrane localization and specifically the role of PI4P in channel function and localization. The phosphatidylinositol 4-kinases (PI4Ks) synthesize PI4P. Our data show that inhibition of PI4K and prolonged decrease of levels of plasma membrane PI4P lead to a decrease in the KCNQ1/KCNE1 channel membrane localization and function. In addition, we show that mutations linked to Long QT syndrome that affect channel interactions with phospholipids lead to a decrease in membrane expression. We show that expression of a LQT1-associated C-terminal deletion mutant abolishes PI4Kinase-mediated decrease in membrane expression and rescues membrane expression for phospholipid-targeting mutations. Our results indicate a novel role for PI4P on ion channel regulation. Our data suggest that decreased membrane PI4P availability to the channel, either due to inhibition of PI4K or as consequence of mutations, dramatically inhibits KCNQ1/KCNE1 channel membrane localization and current. Our results may have implications to regulation of other PI4P binding channels.
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Taurine prevents cardiomyocyte apoptosis by inhibiting the calpain-1/cytochrome c pathway during RVH in broilers. Amino Acids 2020; 52:453-463. [PMID: 32108265 DOI: 10.1007/s00726-020-02824-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 01/30/2020] [Indexed: 12/26/2022]
Abstract
The calpain-1-activated apoptotic pathway plays a key role in right ventricular hypertrophy (RVH). Taurine has been shown to attenuate apoptosis by inhibiting calpain activity. This experiment aimed to determine whether taurine could prevent RVH by inhibiting the calpain-1/cytochrome c apoptotic pathway. The broilers were given 1% taurine dissolved in drinking water and were raised at 10 °C ~ 12 °C from day 21 to day 42. At 21 d, 28 d, 35 d and 42 d, the right ventricular (RV) tissues were collected. Increased RVH index, angiotensin II, norepinephrine and atrial natriuretic peptide mRNA expression were reduced by taurine in the broiler RVs. Taurine obviously inhibited cardiomyocyte apoptosis via maintaining the mitochondrial membrane potential and decreased the activation of caspase-9 and caspase-3 in the broiler RVs. The antioxidant assay demonstrated that taurine enhanced the activities of superoxide dismutase, total antioxidant capacity and glutathione peroxidase and the glutathione/glutathione disulfide ratio. Western blot results revealed that taurine also downregulated the expression of calpain-1 and cytosolic cytochrome c while upregulating the expression of Bcl-2/Bax and mitochondrial cytochrome c in broiler cardiomyocytes during RVH. In summary, we found that taurine could enhance cardiomyocyte antioxidant ability and further prevented cardiomyocyte apoptosis by inhibiting the calpain-1/cytochrome c pathway during RVH in broilers.
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Kurakami K, Norota I, Nasu F, Ohshima S, Nagasawa Y, Konno Y, Obara Y, Ishii K. KCNQ1 is internalized by activation of α1 adrenergic receptors. Biochem Pharmacol 2019; 169:113628. [DOI: 10.1016/j.bcp.2019.113628] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 08/30/2019] [Indexed: 01/25/2023]
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Rajasekaran SS, Illies C, Shears SB, Wang H, Ayala TS, Martins JO, Daré E, Berggren PO, Barker CJ. Protein kinase- and lipase inhibitors of inositide metabolism deplete IP 7 indirectly in pancreatic β-cells: Off-target effects on cellular bioenergetics and direct effects on IP6K activity. Cell Signal 2017; 42:127-133. [PMID: 29042286 PMCID: PMC5765549 DOI: 10.1016/j.cellsig.2017.10.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 10/11/2017] [Accepted: 10/13/2017] [Indexed: 12/22/2022]
Abstract
Inositol pyrophosphates have emerged as important regulators of many critical cellular processes from vesicle trafficking and cytoskeletal rearrangement to telomere length regulation and apoptosis. We have previously demonstrated that 5-di-phosphoinositol pentakisphosphate, IP7, is at a high level in pancreatic β-cells and is important for insulin exocytosis. To better understand IP7 regulation in β-cells, we used an insulin secreting cell line, HIT-T15, to screen a number of different pharmacological inhibitors of inositide metabolism for their impact on cellular IP7. Although the inhibitors have diverse targets, they all perturbed IP7 levels. This made us suspicious that indirect, off-target effects of the inhibitors could be involved. It is known that IP7 levels are decreased by metabolic poisons. The fact that the inositol hexakisphosphate kinases (IP6Ks) have a high Km for ATP makes IP7 synthesis potentially vulnerable to ATP depletion. Furthermore, many kinase inhibitors are targeted to the ATP binding site of kinases, but given the similarity of such sites, high specificity is difficult to achieve. Here, we show that IP7 concentrations in HIT-T15 cells were reduced by inhibitors of PI3K (wortmannin, LY294002), PI4K (Phenylarsine Oxide, PAO), PLC (U73122) and the insulin receptor (HNMPA). Each of these inhibitors also decreased the ATP/ADP ratio. Thus reagents that compromise energy metabolism reduce IP7 indirectly. Additionally, PAO, U73122 and LY294002 also directly inhibited the activity of purified IP6K. These data are of particular concern for those studying signal transduction in pancreatic β-cells, but also highlight the fact that employment of these inhibitors could have erroneously suggested the involvement of key signal transduction pathways in various cellular processes. Conversely, IP7’s role in cellular signal transduction is likely to have been underestimated. In pancreatic β-cells several inhibitors of signal transduction reduce IP7 levels. There is a positive correlation between IP7 reduction and decrease in ATP/ADP. Inhibitors deplete IP7 levels indirectly by decreasing ATP/ADP levels. Some purportedly specific cell-signaling inhibitors directly target IP6K activity. Caution is required in interpreting data obtained using inhibitors of inositide metabolism.
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Affiliation(s)
- Subu Surendran Rajasekaran
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, SE-171 76 Stockholm, Sweden
| | - Christopher Illies
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, SE-171 76 Stockholm, Sweden
| | - Stephen B Shears
- Signal Transduction Laboratory/Inositol Signaling Group, NIEHS, Building 101, Room F239, 111 T.W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Huanchen Wang
- Signal Transduction Laboratory/Inositol Signaling Group, NIEHS, Building 101, Room F239, 111 T.W. Alexander Drive, Research Triangle Park, NC 27709, USA
| | - Thais S Ayala
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, SE-171 76 Stockholm, Sweden; Laboratory of Immunoendocrinology, Department of Clinical and Toxicological Analyses, Faculty of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil
| | - Joilson O Martins
- Laboratory of Immunoendocrinology, Department of Clinical and Toxicological Analyses, Faculty of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil
| | - Elisabetta Daré
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, SE-171 76 Stockholm, Sweden
| | - Per-Olof Berggren
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, SE-171 76 Stockholm, Sweden.
| | - Christopher J Barker
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, SE-171 76 Stockholm, Sweden.
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Li J, Mkrtschjan MA, Lin YH, Russell B. Variation in stiffness regulates cardiac myocyte hypertrophy via signaling pathways. Can J Physiol Pharmacol 2016; 94:1178-1186. [PMID: 27486838 DOI: 10.1139/cjpp-2015-0578] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Much diseased human myocardial tissue is fibrotic and stiff, which increases the work that the ventricular myocytes must perform to maintain cardiac output. The hypothesis tested is that the increased load due to greater stiffness of the substrata drives sarcomere assembly of cells, thus strengthening them. Neonatal rat ventricular myocytes (NRVM) were cultured on polyacrylamide or polydimethylsiloxane substrates with stiffness of 10 kPa, 100 kPa, or 400 kPa, or glass with stiffness of 61.9 GPa. Cell size increased with stiffness. Two signaling pathways were explored, phosphorylation of focal adhesion kinase (p-FAK) and lipids by phosphatidylinositol 4,5-bisphosphate (PIP2). Subcellular distributions of both were determined in the sarcomeric fraction by antibody localization, and total amounts were measured by Western or dot blotting, respectively. More p-FAK and PIP2 distributed to the sarcomeres of NRVM grown on stiffer substrates. Actin assembly involves the actin capping protein Z (CapZ). Both actin and CapZ dynamic exchange were significantly increased on stiffer substrates when assessed by fluorescence recovery after photobleaching (FRAP) of green fluorescent protein tags. Blunting of actin FRAP by FAK inhibition implicates linkage from mechano-signalling pathways to cell growth. Thus, increased stiffness of cardiac disease can be modeled with polymeric materials to understand how the microenvironment regulates cardiac hypertrophy.
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Affiliation(s)
- Jieli Li
- a Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois at Chicago, 835 S. Wolcott Ave, Chicago, IL 60612, USA
| | - Michael A Mkrtschjan
- b Department of Bioengineering, University of Illinois at Chicago, 851 South Morgan Street, Chicago, IL 60607, USA
| | - Ying-Hsi Lin
- a Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois at Chicago, 835 S. Wolcott Ave, Chicago, IL 60612, USA
| | - Brenda Russell
- a Department of Physiology and Biophysics, Center for Cardiovascular Research, University of Illinois at Chicago, 835 S. Wolcott Ave, Chicago, IL 60612, USA.,b Department of Bioengineering, University of Illinois at Chicago, 851 South Morgan Street, Chicago, IL 60607, USA
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Abstract
UNLABELLED In neurons, loss of plasma membrane phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] leads to a decrease in exocytosis and changes in electrical excitability. Restoration of PI(4,5)P2 levels after phospholipase C activation is therefore essential for a return to basal neuronal activity. However, the dynamics of phosphoinositide metabolism have not been analyzed in neurons. We measured dynamic changes of PI(4,5)P2, phosphatidylinositol 4-phosphate, diacylglycerol, inositol 1,4,5-trisphosphate, and Ca(2+) upon muscarinic stimulation in sympathetic neurons from adult male Sprague-Dawley rats with electrophysiological and optical approaches. We used this kinetic information to develop a quantitative description of neuronal phosphoinositide metabolism. The measurements and analysis show and explain faster synthesis of PI(4,5)P2 in sympathetic neurons than in electrically nonexcitable tsA201 cells. They can be used to understand dynamic effects of receptor-mediated phospholipase C activation on excitability and other PI(4,5)P2-dependent processes in neurons. SIGNIFICANCE STATEMENT Phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] is a minor phospholipid in the cytoplasmic leaflet of the plasma membrane. Depletion of PI(4,5)P2 via phospholipase C-mediated hydrolysis leads to a decrease in exocytosis and alters electrical excitability in neurons. Restoration of PI(4,5)P2 is essential for a return to basal neuronal activity. However, the dynamics of phosphoinositide metabolism have not been analyzed in neurons. We studied the dynamics of phosphoinositide metabolism in sympathetic neurons upon muscarinic stimulation and used the kinetic information to develop a quantitative description of neuronal phosphoinositide metabolism. The measurements and analysis show a several-fold faster synthesis of PI(4,5)P2 in sympathetic neurons than in an electrically nonexcitable cell line, and provide a framework for future studies of PI(4,5)P2-dependent processes in neurons.
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Tóth JT, Gulyás G, Tóth DJ, Balla A, Hammond GRV, Hunyady L, Balla T, Várnai P. BRET-monitoring of the dynamic changes of inositol lipid pools in living cells reveals a PKC-dependent PtdIns4P increase upon EGF and M3 receptor activation. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1861:177-87. [PMID: 26692031 DOI: 10.1016/j.bbalip.2015.12.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2015] [Revised: 11/18/2015] [Accepted: 12/11/2015] [Indexed: 10/22/2022]
Abstract
Deciphering many roles played by inositol lipids in signal transduction and membrane function demands experimental approaches that can detect their dynamic accumulation with subcellular accuracy and exquisite sensitivity. The former criterion is met by imaging of fluorescence biosensors in living cells, whereas the latter is facilitated by biochemical measurements from populations. Here, we introduce BRET-based biosensors able to detect rapid changes in inositol lipids in cell populations with both high sensitivity and subcellular resolution in a single, convenient assay. We demonstrate robust and sensitive measurements of PtdIns4P, PtdIns(4,5)P2 and PtdIns(3,4,5)P3 dynamics, as well as changes in cytoplasmic Ins(1,4,5)P3 levels. Measurements were made during either experimental activation of lipid degradation, or PI 3-kinase and phospholipase C mediated signal transduction. Our results reveal a previously unappreciated synthesis of PtdIns4P that accompanies moderate activation of phospholipase C signaling downstream of both EGF and muscarinic M3 receptor activation. This signaling-induced PtdIns4P synthesis relies on protein kinase C, and implicates a feedback mechanism in the control of inositol lipid metabolism during signal transduction.
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Affiliation(s)
- József T Tóth
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary; MTA-SE Laboratory of Molecular Physiology, Budapest, Hungary
| | - Gergő Gulyás
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Dániel J Tóth
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - András Balla
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary; MTA-SE Laboratory of Molecular Physiology, Budapest, Hungary
| | - Gerald R V Hammond
- Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA; Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - László Hunyady
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary; MTA-SE Laboratory of Molecular Physiology, Budapest, Hungary
| | - Tamás Balla
- Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Péter Várnai
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary.
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Xie L, Liang T, Kang Y, Lin X, Sobbi R, Xie H, Chao C, Backx P, Feng ZP, Shyng SL, Gaisano HY. Phosphatidylinositol 4,5-biphosphate (PIP2) modulates syntaxin-1A binding to sulfonylurea receptor 2A to regulate cardiac ATP-sensitive potassium (KATP) channels. J Mol Cell Cardiol 2014; 75:100-10. [DOI: 10.1016/j.yjmcc.2014.07.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 07/15/2014] [Accepted: 07/18/2014] [Indexed: 11/15/2022]
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Li J, Tanhehco EJ, Russell B. Actin dynamics is rapidly regulated by the PTEN and PIP2 signaling pathways leading to myocyte hypertrophy. Am J Physiol Heart Circ Physiol 2014; 307:H1618-25. [PMID: 25260617 DOI: 10.1152/ajpheart.00393.2014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Mature cardiac myocytes are terminally differentiated, and the heart has limited capacity to replace lost myocytes. Thus adaptation of myocyte size plays an important role in the determination of cardiac function. The hypothesis tested is that regulation of the dynamic exchange of actin leads to cardiac hypertrophy. ANG II was used as a hypertrophic stimulant in mouse heart and neonatal rat ventricular myocytes (NRVMs) in culture for assessment of a mechanism for regulation of actin dynamics by phosphatidylinositol 4,5-bisphosphate (PIP2). Actin dynamics in NRVMs rapidly increased in a PIP2-dependent manner, measured by imaging and fluorescence recovery after photobleaching (FRAP). A significant increase in PIP2 levels was found by immunoblotting in both adult mouse heart tissue and cultured NRVMs. Inhibition of phosphatase and tensin homolog (PTEN) in NRVMs markedly blunted ANG II-induced increases in actin dynamics, the PIP2 level, and cell size. Furthermore, PTEN activity was dramatically upregulated in ANG II-treated NRVMs but downregulated when PTEN inhibitors were used. The time course of the rise in the PIP2 level was inversely related to the fall in the PIP3 level, which was significant by 30 min in ANG II-treated NRVMs. However, significant translocation of PTEN to the plasma membrane occurred by 10 min, suggesting a crucial initial step for PTEN for the cellular responses to ANG II. In conclusion, PTEN and PIP2 signaling may play an important role in myocyte hypertrophy by the regulation of actin filament dynamics, which is induced by ANG II stimulation.
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Affiliation(s)
- Jieli Li
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois
| | - Elaine J Tanhehco
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois
| | - Brenda Russell
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois
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