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Banjac K, Obradovic M, Zafirovic S, Essack M, Gluvic Z, Sunderic M, Nedic O, Isenovic ER. The involvement of Akt, mTOR, and S6K in the in vivo effect of IGF-1 on the regulation of rat cardiac Na +/K +-ATPase. Mol Biol Rep 2024; 51:517. [PMID: 38622478 DOI: 10.1007/s11033-024-09451-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 03/15/2024] [Indexed: 04/17/2024]
Abstract
BACKGROUND We previously demonstrated that insulin-like growth factor-1 (IGF-1) regulates sodium/potassium adenosine triphosphatase (Na+/K+-ATPase) in vascular smooth muscle cells (VSMC) via phosphatidylinositol-3 kinase (PI3K). Taking into account that others' work show that IGF-1 activates the PI3K/protein kinase B (Akt) signaling pathway in many different cells, we here further questioned if the Akt/mammalian target of rapamycin (mTOR)/ribosomal protein p70 S6 kinase (S6K) pathway stimulates Na+/K+-ATPase, an essential protein for maintaining normal heart function. METHODS AND RESULTS There were 14 adult male Wistar rats, half of whom received bolus injections of IGF-1 (50 μg/kg) for 24 h. We evaluated cardiac Na+/K+-ATPase expression, activity, and serum IGF-1 levels. Additionally, we examined the phosphorylated forms of the following proteins: insulin receptor substrate (IRS), phosphoinositide-dependent kinase-1 (PDK-1), Akt, mTOR, S6K, and α subunit of Na+/K+-ATPase. Additionally, the mRNA expression of the Na+/K+-ATPase α1 subunit was evaluated. Treatment with IGF-1 increases levels of serum IGF-1 and stimulates Na+/K+-ATPase activity, phosphorylation of α subunit of Na+/K+-ATPase on Ser23, and protein expression of α2 subunit. Furthermore, IGF-1 treatment increased phosphorylation of IRS-1 on Tyr1222, Akt on Ser473, PDK-1 on Ser241, mTOR on Ser2481 and Ser2448, and S6K on Thr421/Ser424. The concentration of IGF-1 in serum positively correlates with Na+/K+-ATPase activity and the phosphorylated form of mTOR (Ser2448), while Na+/K+-ATPase activity positively correlates with the phosphorylated form of IRS-1 (Tyr1222) and mTOR (Ser2448). CONCLUSION These results indicate that the Akt/mTOR/S6K signalling pathway may be involved in the IGF-1 regulating cardiac Na+/K+-ATPase expression and activity.
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Affiliation(s)
- Katarina Banjac
- Department of Radiobiology and Molecular Genetics, "VINCA" Institute of Nuclear Sciences - National Institute of the Republic of Serbia, University of Belgrade, P.O.Box 522, Belgrade, 11000, Serbia
| | - Milan Obradovic
- Department of Radiobiology and Molecular Genetics, "VINCA" Institute of Nuclear Sciences - National Institute of the Republic of Serbia, University of Belgrade, P.O.Box 522, Belgrade, 11000, Serbia.
| | - Sonja Zafirovic
- Department of Radiobiology and Molecular Genetics, "VINCA" Institute of Nuclear Sciences - National Institute of the Republic of Serbia, University of Belgrade, P.O.Box 522, Belgrade, 11000, Serbia
| | - Magbubah Essack
- Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Kingdom of Saudi Arabia
| | - Zoran Gluvic
- Clinic of Internal Medicine, School of Medicine, University Clinical-Hospital Centre Zemun-Belgrade, University of Belgrade, Vukova 9, Belgrade, 11080, Serbia
| | - Milos Sunderic
- Institute for the Application of Nuclear Energy, Department for Metabolism, University of Belgrade, Banatska 31b, Belgrade, Serbia
| | - Olgica Nedic
- Institute for the Application of Nuclear Energy, Department for Metabolism, University of Belgrade, Banatska 31b, Belgrade, Serbia
| | - Esma R Isenovic
- Department of Radiobiology and Molecular Genetics, "VINCA" Institute of Nuclear Sciences - National Institute of the Republic of Serbia, University of Belgrade, P.O.Box 522, Belgrade, 11000, Serbia
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Hanna FS, Alkhouri S, Rajagopalan C, Ji K, Mattingly RR, Yingst DR. Ang II acutely stimulates Na,K-pump in cells from proximal tubules by increasing its phosphorylation at S938 via a PI3K/AKT pathway. Physiol Rep 2022; 10:e15508. [PMID: 36377055 PMCID: PMC9663852 DOI: 10.14814/phy2.15508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Revised: 10/10/2022] [Accepted: 10/14/2022] [Indexed: 06/16/2023] Open
Abstract
Angiotensin II (Ang II)-dependent stimulation of the AT1 receptor in proximal tubules increases sodium reabsorption and blood pressure. Reabsorption is driven by the Na,K-pump that is acutely stimulated by Ang II, which requires phosphorylation of serine-938 (S938). This site is present in humans and only known to phosphorylated by PKA. Yet, activation of AT1 decreases cAMP required to activate PKA and inhibiting PKA does not block Ang II-dependent phosphorylation of S938. We tested the hypothesis that Ang II-dependent activation is mediated via increased phosphorylation at S938 through a PI3K/AKT-dependent pathway. Experiments were conducted using opossum kidney cells, a proximal tubule cell line, stably co-expressing the AT1 receptor and either the wild-type (α-1.wild-type) or an alanine substituted (α-1.S938A) form of rat kidney Na,K-pump. A 5-min exposure to 10 pM Ang II significantly activated Na,K-pump activity (56%) measured as short-circuit current across polarized α-1.wild-type cells. Wortmannin, at a concentration that selectively inhibits PI3K, blocked that Ang II-dependent activation. Ang II did not stimulate Na,K-pump activity in α-1.S938A cells. Ang II at 10 and 100 pM increased phosphorylation at S938 in α-1.wild-type cells measured in whole cell lysates. The increase was inhibited by wortmannin plus H-89, an inhibitor of PKA, not by either alone. Ang II activated AKT inhibited by wortmannin, not H-89. These data support our hypothesis and show that Ang II-dependent phosphorylation at S938 stimulates Na,K-pump activity and transcellular sodium transport.
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Affiliation(s)
- Fadia S. Hanna
- Department of PhysiologyWayne State University, School of MedicineDetroitMichiganUSA
| | - Samaa Alkhouri
- Department of PhysiologyWayne State University, School of MedicineDetroitMichiganUSA
| | - Carthic Rajagopalan
- Department of PhysiologyWayne State University, School of MedicineDetroitMichiganUSA
| | - Kyungmin Ji
- Department of PharmacologyWayne State University, School of MedicineDetroitMichiganUSA
| | - Raymond R. Mattingly
- Present address:
Department of Pharmacology & ToxicologyBrody School of Medicine, East Carolina UniversityGreenvilleNorth CarolinaUSA
| | - Douglas R. Yingst
- Department of PhysiologyWayne State University, School of MedicineDetroitMichiganUSA
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Stimulation of Na +/K +-ATPase with an Antibody against Its 4 th Extracellular Region Attenuates Angiotensin II-Induced H9c2 Cardiomyocyte Hypertrophy via an AMPK/SIRT3/PPAR γ Signaling Pathway. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2019; 2019:4616034. [PMID: 31636805 PMCID: PMC6766118 DOI: 10.1155/2019/4616034] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Revised: 07/09/2019] [Accepted: 08/02/2019] [Indexed: 02/06/2023]
Abstract
Activation of the renin-angiotensin system (RAS) contributes to the pathogenesis of cardiovascular diseases. Sodium potassium ATPase (NKA) expression and activity are often regulated by angiotensin II (Ang II). This study is aimed at investigating whether DR-Ab, an antibody against 4th extracellular region of NKA, can protect Ang II-induced cardiomyocyte hypertrophy. Our results showed that Ang II treatment significantly reduced NKA activity and membrane expression. Pretreatment with DR-Ab preserved cell size in Ang II-induced cardiomyopathy by stabilizing the plasma membrane expression of NKA and restoring its activity. DR-Ab reduced intracellular ROS generation through inhibition of NADPH oxidase activity and protection of mitochondrial functions in Ang II-treated H9c2 cardiomyocytes. Pharmacological manipulation and Western blotting analysis demonstrated the cardioprotective effects were mediated by the activation of the AMPK/Sirt-3/PPARγ signaling pathway. Taken together, our results suggest that dysfunction of NKA is an important mechanism for Ang II-induced cardiomyopathy and DR-Ab may be a novel and promising therapeutic approach to treat cardiomyocyte hypertrophy.
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Massey KJ, Li Q, Rossi NF, Keezer SM, Mattingly RR, Yingst DR. Phosphorylation of rat kidney Na-K pump at Ser938 is required for rapid angiotensin II-dependent stimulation of activity and trafficking in proximal tubule cells. Am J Physiol Cell Physiol 2015; 310:C227-32. [PMID: 26582472 DOI: 10.1152/ajpcell.00113.2015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 11/09/2015] [Indexed: 12/23/2022]
Abstract
How angiotensin (ANG) II acutely stimulates the Na-K pump in proximal tubules is only partially understood, limiting insight into how ANG II increases blood pressure. First, we tested whether ANG II increases the number of pumps in plasma membranes of native rat proximal tubules under conditions of rapid activation. We found that exposure to 100 pM ANG II for 2 min, which was previously shown to increase affinity of the Na-K pump for Na and stimulate activity threefold, increased the amount of the Na-K pump in plasma membranes of native tubules by 33%. Second, we tested whether previously observed increases in phosphorylation of the Na-K pump at Ser(938) were part of the stimulatory mechanism. These experiments were carried out in opossum kidney cells, cultured proximal tubules stably coexpressing the ANG type 1 (AT1) receptor, and either wild-type or a S938A mutant of rat kidney Na-K pump under conditions found by others to stimulate activity. We found that 10 min of incubation in 10 pM ANG II stimulated activity of wild-type pumps from 2.3 to 3.5 nmol K · mg protein(-1) · min(-1) and increased the amount of the pump in the plasma membrane by 80% but had no effect on cells expressing the S938A mutant. We conclude that acute stimulation of Na-K pump activity in native rat proximal tubules includes increased trafficking to the plasma membrane and that phosphorylation at Ser(938) is part of the mechanism by which ANG II directly stimulates activity and trafficking of the rat kidney Na-K pump in opossum kidney cells.
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Affiliation(s)
- Katherine J Massey
- Department of Physiology, School of Medicine, Wayne State University, Detroit, Michigan
| | - Quanwen Li
- Department of Pharmacology, School of Medicine, Wayne State University, Detroit, Michigan
| | - Noreen F Rossi
- Department of Physiology, School of Medicine, Wayne State University, Detroit, Michigan; Department of Internal Medicine, School of Medicine, Wayne State University, Detroit, Michigan; John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan
| | | | - Raymond R Mattingly
- Department of Pharmacology, School of Medicine, Wayne State University, Detroit, Michigan
| | - Douglas R Yingst
- Department of Physiology, School of Medicine, Wayne State University, Detroit, Michigan;
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Garcia A, Rasmussen HH, Apell HJ, Clarke RJ. Kinetic comparisons of heart and kidney Na+,K(+)-ATPases. Biophys J 2013; 103:677-88. [PMID: 22947929 DOI: 10.1016/j.bpj.2012.07.032] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Revised: 07/17/2012] [Accepted: 07/23/2012] [Indexed: 10/28/2022] Open
Abstract
Most kinetic measurements of the partial reactions of Na(+),K(+)-ATPase have been conducted on enzyme from mammalian kidney. Here we present a kinetic model that is based on the available equilibrium and kinetic parameters of purified kidney enzyme, and allows predictions of its steady-state turnover and pump current in intact cells as a function of ion and ATP concentrations and the membrane voltage. Using this model, we calculated the expected dependence of the pump current on voltage and extracellular Na(+) concentration. The simulations indicate a lower voltage dependence at negative potentials of the kidney enzyme in comparison with heart muscle Na(+),K(+)-ATPase, in agreement with experimental results. The voltage dependence is enhanced at high extracellular Na(+) concentrations. This effect can be explained by a voltage-dependent depopulation of extracellular K(+) ion binding sites on the E2P state and an increase in the proportion of enzyme in the E1P(Na(+))(3) state in the steady state. This causes a decrease in the effective rate constant for occlusion of K(+) by the E2P state and hence a drop in turnover. Around a membrane potential of zero, negligible voltage dependence is observed because the voltage-independent E2(K(+))(2) → E1 + 2K(+) transition is the major rate-determining step.
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Affiliation(s)
- Alvaro Garcia
- Department of Cardiology, Royal North Shore Hospital, and Kolling Institute, University of Sydney, Sydney, Australia
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