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Tóth AD, Soltész-Katona E, Kis K, Guti V, Gilzer S, Prokop S, Boros R, Misák Á, Balla A, Várnai P, Turiák L, Ács A, Drahos L, Inoue A, Hunyady L, Turu G. ArreSTick motif controls β-arrestin-binding stability and extends phosphorylation-dependent β-arrestin interactions to non-receptor proteins. Cell Rep 2024; 43:114241. [PMID: 38758647 DOI: 10.1016/j.celrep.2024.114241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 03/11/2024] [Accepted: 05/01/2024] [Indexed: 05/19/2024] Open
Abstract
The binding and function of β-arrestins are regulated by specific phosphorylation motifs present in G protein-coupled receptors (GPCRs). However, the exact arrangement of phosphorylated amino acids responsible for establishing a stable interaction remains unclear. We employ a 1D sequence convolution model trained on GPCRs with established β-arrestin-binding properties. With this approach, amino acid motifs characteristic of GPCRs that form stable interactions with β-arrestins can be identified, a pattern that we name "arreSTick." Intriguingly, the arreSTick pattern is also present in numerous non-receptor proteins. Using proximity biotinylation assay and mass spectrometry analysis, we demonstrate that the arreSTick motif controls the interaction between many non-receptor proteins and β-arrestin2. The HIV-1 Tat-specific factor 1 (HTSF1 or HTATSF1), a nuclear transcription factor, contains the arreSTick pattern, and its subcellular localization is influenced by β-arrestin2. Our findings unveil a broader role for β-arrestins in phosphorylation-dependent interactions, extending beyond GPCRs to encompass non-receptor proteins as well.
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Affiliation(s)
- András Dávid Tóth
- Institute of Molecular Life Sciences, Centre of Excellence of the Hungarian Academy of Sciences, HUN-REN Research Centre for Natural Sciences, Magyar Tudósok krt. 2., 1117 Budapest, Hungary; Department of Internal Medicine and Haematology, Semmelweis University, Szentkirályi street 46, 1088 Budapest, Hungary
| | - Eszter Soltész-Katona
- Institute of Molecular Life Sciences, Centre of Excellence of the Hungarian Academy of Sciences, HUN-REN Research Centre for Natural Sciences, Magyar Tudósok krt. 2., 1117 Budapest, Hungary; Department of Physiology, Semmelweis University, Tűzoltó street 37-47, 1094 Budapest, Hungary
| | - Katalin Kis
- Department of Physiology, Semmelweis University, Tűzoltó street 37-47, 1094 Budapest, Hungary
| | - Viktor Guti
- Department of Physiology, Semmelweis University, Tűzoltó street 37-47, 1094 Budapest, Hungary
| | - Sharon Gilzer
- Department of Physiology, Semmelweis University, Tűzoltó street 37-47, 1094 Budapest, Hungary
| | - Susanne Prokop
- Department of Physiology, Semmelweis University, Tűzoltó street 37-47, 1094 Budapest, Hungary
| | - Roxána Boros
- Department of Physiology, Semmelweis University, Tűzoltó street 37-47, 1094 Budapest, Hungary
| | - Ádám Misák
- Department of Physiology, Semmelweis University, Tűzoltó street 37-47, 1094 Budapest, Hungary
| | - András Balla
- Department of Physiology, Semmelweis University, Tűzoltó street 37-47, 1094 Budapest, Hungary; HUN-REN SE Hungarian Research Network Laboratory of Molecular Physiology, Budapest, Hungary
| | - Péter Várnai
- Department of Physiology, Semmelweis University, Tűzoltó street 37-47, 1094 Budapest, Hungary; HUN-REN SE Hungarian Research Network Laboratory of Molecular Physiology, Budapest, Hungary
| | - Lilla Turiák
- Institute of Organic Chemistry, HUN-REN Research Centre for Natural Sciences, Magyar Tudósok krt. 2., 1117 Budapest, Hungary
| | - András Ács
- Institute of Organic Chemistry, HUN-REN Research Centre for Natural Sciences, Magyar Tudósok krt. 2., 1117 Budapest, Hungary
| | - László Drahos
- Institute of Organic Chemistry, HUN-REN Research Centre for Natural Sciences, Magyar Tudósok krt. 2., 1117 Budapest, Hungary
| | - Asuka Inoue
- Molecular and Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - László Hunyady
- Institute of Molecular Life Sciences, Centre of Excellence of the Hungarian Academy of Sciences, HUN-REN Research Centre for Natural Sciences, Magyar Tudósok krt. 2., 1117 Budapest, Hungary; Department of Physiology, Semmelweis University, Tűzoltó street 37-47, 1094 Budapest, Hungary.
| | - Gábor Turu
- Institute of Molecular Life Sciences, Centre of Excellence of the Hungarian Academy of Sciences, HUN-REN Research Centre for Natural Sciences, Magyar Tudósok krt. 2., 1117 Budapest, Hungary; Department of Physiology, Semmelweis University, Tűzoltó street 37-47, 1094 Budapest, Hungary.
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Tóth DJ, Tóth JT, Damouni A, Hunyady L, Várnai P. Effect of hormone-induced plasma membrane phosphatidylinositol 4,5-bisphosphate depletion on receptor endocytosis suggests the importance of local regulation in phosphoinositide signaling. Sci Rep 2024; 14:291. [PMID: 38168911 PMCID: PMC10761818 DOI: 10.1038/s41598-023-50732-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 12/24/2023] [Indexed: 01/05/2024] Open
Abstract
Phosphatidylinositol 4,5-bisphosphate (PIP2) has been shown to be critical for the endocytosis of G protein-coupled receptors (GPCRs). We have previously demonstrated that depletion of PIP2 by chemically induced plasma membrane (PM) recruitment of a 5-phosphatase domain prevents the internalization of the β2 adrenergic receptor (β2AR) from the PM to early endosomes. In this study, we tested the effect of hormone-induced PM PIP2 depletion on β2AR internalization using type-1 angiotensin receptor (AT1R) or M3 muscarinic acetylcholine receptor (M3R). We followed the endocytic route of β2ARs in HEK 293T cells using bioluminescence resonance energy transfer between the receptor and endosome marker Rab5. To compare the effect of lipid depletion by different means, we created and tested an AT1R fusion protein that is capable of both recruitment-based and hormone-induced depletion methods. The rate of PM PIP2 depletion was measured using a biosensor based on the PH domain of phospholipase Cδ1. As expected, β2AR internalization was inhibited when PIP2 depletion was evoked by recruiting 5-phosphatase to PM-anchored AT1R. A similar inhibition occurred when wild-type AT1R was activated by adding angiotensin II. However, stimulation of the desensitization/internalization-impaired mutant AT1R (TSTS/4A) caused very little inhibition of β2AR internalization, despite the higher rate of measurable PIP2 depletion. Interestingly, inhibition of PIP2 resynthesis with the selective PI4KA inhibitor GSK-A1 had little effect on the change in PH-domain-measured PM PIP2 levels but did significantly decrease β2AR internalization upon either AT1R or M3R activation, indicating the importance of a locally synthetized phosphoinositide pool in the regulation of this process.
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Affiliation(s)
- Dániel J Tóth
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Tűzoltó utca 37-47, 1094, Hungary
- HUN-REN-SU Molecular Physiology Research Group, Hungarian Research Network and Semmelweis University, Budapest, Hungary
| | - József T Tóth
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Tűzoltó utca 37-47, 1094, Hungary
- Department of Anaesthesiology and Intensive Therapy, Faculty of Medicine, Semmelweis University, Budapest, Üllői út 78/B, 1082, Hungary
| | - Amir Damouni
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Tűzoltó utca 37-47, 1094, Hungary
| | - László Hunyady
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Tűzoltó utca 37-47, 1094, Hungary
- Institute of Enzymology, Centre of Excellence of the Hungarian Academy of Sciences, HUN-REN Research Centre for Natural Sciences, Budapest, Magyar tudósok körútja 2, 1117, Hungary
| | - Péter Várnai
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Tűzoltó utca 37-47, 1094, Hungary.
- HUN-REN-SU Molecular Physiology Research Group, Hungarian Research Network and Semmelweis University, Budapest, Hungary.
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Csordás G, Weaver D, Várnai P, Hajnóczky G. Supralinear Dependence of the IP 3 Receptor-to-Mitochondria Local Ca 2+ Transfer on the Endoplasmic Reticulum Ca 2+ Loading. Contact (Thousand Oaks) 2024; 7:25152564241229273. [PMID: 38362008 PMCID: PMC10868505 DOI: 10.1177/25152564241229273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Revised: 12/31/2023] [Accepted: 01/12/2024] [Indexed: 02/17/2024]
Abstract
Calcium signal propagation from endoplasmic reticulum (ER) to mitochondria regulates a multitude of mitochondrial and cell functions, including oxidative ATP production and cell fate decisions. Ca2+ transfer is optimal at the ER-mitochondrial contacts, where inositol 1,4,5-trisphosphate (IP3) receptors (IP3R) can locally expose the mitochondrial Ca2+ uniporter (mtCU) to high [Ca2+] nanodomains. The Ca2+ loading state of the ER (Ca2 + ER) can vary broadly in physiological and pathological scenarios, however, the correlation between Ca2 + ER and the local Ca2+ transfer is unclear. Here, we studied IP3-induced Ca2+ transfer to mitochondria at different Ca2 + ER in intact and permeabilized RBL-2H3 cells via fluorescence measurements of cytoplasmic [Ca2+] ([Ca2+]c) and mitochondrial matrix [Ca2+] ([Ca2+]m). Preincubation of intact cells in high versus low extracellular [Ca2+] caused disproportionally greater increase in [Ca2+]m than [Ca2+]c responses to IP3-mobilizing agonist. Increasing Ca2 + ER by small Ca2+ boluses in suspensions of permeabilized cells supralinearly enhanced the mitochondrial Ca2+ uptake from IP3-induced Ca2+ release. The IP3-induced local [Ca2+] spikes exposing the mitochondrial surface measured using a genetically targeted sensor appeared to linearly correlate with Ca2 + ER, indicating that amplification happened in the mitochondria. Indeed, overexpression of an EF-hand deficient mutant of the mtCU gatekeeper MICU1 reduced the cooperativity of mitochondrial Ca2+ uptake. Interestingly, the IP3-induced [Ca2+]m signal plateaued at high Ca2 + ER, indicating activation of a matrix Ca2+ binding/chelating species. Mitochondria thus seem to maintain a "working [Ca2+]m range" via a low-affinity and high-capacity buffer species, and the ER loading steeply enhances the IP3R-linked [Ca2+]m signals in this working range.
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Affiliation(s)
- György Csordás
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - David Weaver
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Péter Várnai
- Department of Physiology, Semmelweis Medical University, Budapest, Hungary
| | - György Hajnóczky
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
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Gal A, Balicza P, Weaver D, Naghdi S, Joseph SK, Várnai P, Gyuris T, Horváth A, Nagy L, Seifert EL, Molnar MJ, Hajnóczky G. MSTO1 is a cytoplasmic pro-mitochondrial fusion protein, whose mutation induces myopathy and ataxia in humans. EMBO Mol Med 2023; 15:e17911. [PMID: 37431817 PMCID: PMC10405051 DOI: 10.15252/emmm.202317911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 06/07/2023] [Indexed: 07/12/2023] Open
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Nichtová Z, Fernandez-Sanz C, De La Fuente S, Yuan Y, Hurst S, Lanvermann S, Tsai HY, Weaver D, Baggett A, Thompson C, Bouchet-Marquis C, Várnai P, Seifert EL, Dorn GW, Sheu SS, Csordás G. Enhanced Mitochondria-SR Tethering Triggers Adaptive Cardiac Muscle Remodeling. Circ Res 2023; 132:e171-e187. [PMID: 37057625 PMCID: PMC10213149 DOI: 10.1161/circresaha.122.321833] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 03/29/2023] [Indexed: 04/15/2023]
Abstract
BACKGROUND Cardiac contractile function requires high energy from mitochondria, and Ca2+ from the sarcoplasmic reticulum (SR). Via local Ca2+ transfer at close mitochondria-SR contacts, cardiac excitation feedforward regulates mitochondrial ATP production to match surges in demand (excitation-bioenergetics coupling). However, pathological stresses may cause mitochondrial Ca2+ overload, excessive reactive oxygen species production and permeability transition, risking homeostatic collapse and myocyte loss. Excitation-bioenergetics coupling involves mitochondria-SR tethers but the role of tethering in cardiac physiology/pathology is debated. Endogenous tether proteins are multifunctional; therefore, nonselective targets to scrutinize interorganelle linkage. Here, we assessed the physiological/pathological relevance of selective chronic enhancement of cardiac mitochondria-SR tethering. METHODS We introduced to mice a cardiac muscle-specific engineered tether (linker) transgene with a fluorescent protein core and deployed 2D/3D electron microscopy, biochemical approaches, fluorescence imaging, in vivo and ex vivo cardiac performance monitoring and stress challenges to characterize the linker phenotype. RESULTS Expressed in the mature cardiomyocytes, the linker expanded and tightened individual mitochondria-junctional SR contacts; but also evoked a marked remodeling with large dense mitochondrial clusters that excluded dyads. Yet, excitation-bioenergetics coupling remained well-preserved, likely due to more longitudinal mitochondria-dyad contacts and nanotunnelling between mitochondria exposed to junctional SR and those sealed away from junctional SR. Remarkably, the linker decreased female vulnerability to acute massive β-adrenergic stress. It also reduced myocyte death and mitochondrial calcium-overload-associated myocardial impairment in ex vivo ischemia/reperfusion injury. CONCLUSIONS We propose that mitochondria-SR/endoplasmic reticulum contacts operate at a structural optimum. Although acute changes in tethering may cause dysfunction, upon chronic enhancement of contacts from early life, adaptive remodeling of the organelles shifts the system to a new, stable structural optimum. This remodeling balances the individually enhanced mitochondrion-junctional SR crosstalk and excitation-bioenergetics coupling, by increasing the connected mitochondrial pool and, presumably, Ca2+/reactive oxygen species capacity, which then improves the resilience to stresses associated with dysregulated hyperactive Ca2+ signaling.
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Affiliation(s)
- Zuzana Nichtová
- MitoCare, Pathology and Genomic Medicine, TJUH, Philadelphia, PA, USA
| | - Celia Fernandez-Sanz
- Center of Translational Medicine, TJUH, Philadelphia, PA, USA
- These authors contributed equally
| | - Sergio De La Fuente
- Center of Translational Medicine, TJUH, Philadelphia, PA, USA
- These authors contributed equally
| | - Yuexing Yuan
- Center of Translational Medicine, TJUH, Philadelphia, PA, USA
| | - Stephen Hurst
- MitoCare, Pathology and Genomic Medicine, TJUH, Philadelphia, PA, USA
| | | | - Hui-Ying Tsai
- Center of Translational Medicine, TJUH, Philadelphia, PA, USA
| | - David Weaver
- MitoCare, Pathology and Genomic Medicine, TJUH, Philadelphia, PA, USA
| | - Ariele Baggett
- MitoCare, Pathology and Genomic Medicine, TJUH, Philadelphia, PA, USA
| | | | | | - Péter Várnai
- Department of Physiology, Faculty of Medicine, Semmelweis Univ., Budapest, Hungary
| | - Erin L Seifert
- MitoCare, Pathology and Genomic Medicine, TJUH, Philadelphia, PA, USA
| | - Gerald W Dorn
- Center for Pharmacogenomics, John T. Milliken Dep. Med., WUSM, St Louis, MO, USA
| | - Shey-Shing Sheu
- Center of Translational Medicine, TJUH, Philadelphia, PA, USA
| | - György Csordás
- MitoCare, Pathology and Genomic Medicine, TJUH, Philadelphia, PA, USA
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Cyert M, Ulengin‐Talkish I, Parson MA, Jenkins ML, Roy J, Shih AZ, St‐Denis N, Gulyas G, Balla T, Gingras A, Várnai P, Conibear E, Burke JE. Palmitoylation Targets the Calcineurin Phosphatase to the Phosphatidylinositol 4‐kinase Complex at the Plasma Membrane. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.r6277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | | | | | - Alexis Z. Shih
- Medical GeneticsUniversity of British ColumbiaVancouverBC
| | - Nicole St‐Denis
- Lunenfeld‐Tanenbaum Research Institute at Mount Sinai HospitalUniversity of TorontoTorontoON
| | - Gergo Gulyas
- Section on Molecular Signal TransductionNational Institute of Child Health and Human DevelopmentBethesdaMD
| | - Tamas Balla
- Section on Molecular Signal TransductionNational Institute of Child Health and Human DevelopmentBethesdaMD
| | - Anne‐Claude Gingras
- Lunenfeld‐Tanenbaum Research Institute at Mount Sinai HospitalUniversity of TorontoTorontoON
| | | | | | - John E. Burke
- Biochemistry and MicrobiologyUniversity of VictoriaVictoriaBC
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Barsi S, Papp H, Valdeolivas A, Tóth DJ, Kuczmog A, Madai M, Hunyady L, Várnai P, Saez-Rodriguez J, Jakab F, Szalai B. Computational drug repurposing against SARS-CoV-2 reveals plasma membrane cholesterol depletion as key factor of antiviral drug activity. PLoS Comput Biol 2022; 18:e1010021. [PMID: 35404937 PMCID: PMC9022874 DOI: 10.1371/journal.pcbi.1010021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 04/21/2022] [Accepted: 03/15/2022] [Indexed: 01/09/2023] Open
Abstract
Comparing SARS-CoV-2 infection-induced gene expression signatures to drug treatment-induced gene expression signatures is a promising bioinformatic tool to repurpose existing drugs against SARS-CoV-2. The general hypothesis of signature-based drug repurposing is that drugs with inverse similarity to a disease signature can reverse disease phenotype and thus be effective against it. However, in the case of viral infection diseases, like SARS-CoV-2, infected cells also activate adaptive, antiviral pathways, so that the relationship between effective drug and disease signature can be more ambiguous. To address this question, we analysed gene expression data from in vitro SARS-CoV-2 infected cell lines, and gene expression signatures of drugs showing anti-SARS-CoV-2 activity. Our extensive functional genomic analysis showed that both infection and treatment with in vitro effective drugs leads to activation of antiviral pathways like NFkB and JAK-STAT. Based on the similarity-and not inverse similarity-between drug and infection-induced gene expression signatures, we were able to predict the in vitro antiviral activity of drugs. We also identified SREBF1/2, key regulators of lipid metabolising enzymes, as the most activated transcription factors by several in vitro effective antiviral drugs. Using a fluorescently labeled cholesterol sensor, we showed that these drugs decrease the cholesterol levels of plasma-membrane. Supplementing drug-treated cells with cholesterol reversed the in vitro antiviral effect, suggesting the depleting plasma-membrane cholesterol plays a key role in virus inhibitory mechanism. Our results can help to more effectively repurpose approved drugs against SARS-CoV-2, and also highlights key mechanisms behind their antiviral effect.
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Affiliation(s)
- Szilvia Barsi
- Semmelweis University, Faculty of Medicine, Department of Physiology, Budapest, Hungary
| | - Henrietta Papp
- National Laboratory of Virology, University of Pécs, Pécs, Hungary
- Institute of Biology, Faculty of Sciences, University of Pécs, Pécs, Hungary
| | - Alberto Valdeolivas
- Heidelberg University, Faculty of Medicine, and Heidelberg University Hospital, Institute for Computational Biomedicine, Bioquant, Heidelberg, Germany
| | - Dániel J. Tóth
- Semmelweis University, Faculty of Medicine, Department of Physiology, Budapest, Hungary
| | - Anett Kuczmog
- National Laboratory of Virology, University of Pécs, Pécs, Hungary
- Institute of Biology, Faculty of Sciences, University of Pécs, Pécs, Hungary
| | - Mónika Madai
- National Laboratory of Virology, University of Pécs, Pécs, Hungary
- Institute of Biology, Faculty of Sciences, University of Pécs, Pécs, Hungary
| | - László Hunyady
- Semmelweis University, Faculty of Medicine, Department of Physiology, Budapest, Hungary
- MTA-SE Laboratory of Molecular Physiology, Budapest, Hungary
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, Hungary
| | - Péter Várnai
- Semmelweis University, Faculty of Medicine, Department of Physiology, Budapest, Hungary
- MTA-SE Laboratory of Molecular Physiology, Budapest, Hungary
| | - Julio Saez-Rodriguez
- Heidelberg University, Faculty of Medicine, and Heidelberg University Hospital, Institute for Computational Biomedicine, Bioquant, Heidelberg, Germany
| | - Ferenc Jakab
- National Laboratory of Virology, University of Pécs, Pécs, Hungary
- Institute of Biology, Faculty of Sciences, University of Pécs, Pécs, Hungary
| | - Bence Szalai
- Semmelweis University, Faculty of Medicine, Department of Physiology, Budapest, Hungary
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Durst M, Könczöl K, Ocskay K, Sípos K, Várnai P, Szilvásy-Szabó A, Fekete C, Tóth ZE. Hypothalamic Nesfatin-1 Resistance May Underlie the Development of Type 2 Diabetes Mellitus in Maternally Undernourished Non-obese Rats. Front Neurosci 2022; 16:828571. [PMID: 35386592 PMCID: PMC8978526 DOI: 10.3389/fnins.2022.828571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 02/08/2022] [Indexed: 11/13/2022] Open
Abstract
Intrauterine growth retardation (IUGR) poses a high risk for developing late-onset, non-obese type 2 diabetes (T2DM). The exact mechanism underlying this phenomenon is unknown, although the contribution of the central nervous system is recognized. The main hypothalamic nuclei involved in the homeostatic regulation express nesfatin-1, an anorexigenic neuropeptide and identified regulator of blood glucose level. Using intrauterine protein restricted rat model (PR) of IUGR, we investigated, whether IUGR alters the function of nesfatin-1. We show that PR rats develop fat preference and impaired glucose homeostasis by adulthood, while the body composition and caloric intake of normal nourished (NN) and PR rats are similar. Plasma nesfatin-1 levels are unaffected by IUGR in both neonates and adults, but pro-nesfatin-1 mRNA expression is upregulated in the hypothalamus of adult PR animals. We find that centrally injected nesfatin-1 inhibits the fasting induced neuronal activation in the hypothalamic arcuate nucleus in adult NN rats. This effect of nesfatin-1 is not seen in PR rats. The anorexigenic effect of centrally injected nesfatin-1 is also reduced in adult PR rats. Moreover, chronic central nesfatin-1 administration improves the glucose tolerance and insulin sensitivity in NN rats but not in PR animals. Birth dating of nesfatin-1 cells by bromodeoxyuridine (BrDU) reveals that formation of nesfatin-1 cells in the hypothalamus of PR rats is disturbed. Our results suggest that adult PR rats acquire hypothalamic nesfatin-1-resistance, probably due to the altered development of the hypothalamic nesfatin-1 cells. Hypothalamic nesfatin-1-resistance, in turn, may contribute to the development of non-obese type T2DM.
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Affiliation(s)
- Máté Durst
- Laboratory of Neuroendocrinology and in situ Hybridization, Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, Hungary
| | - Katalin Könczöl
- Laboratory of Neuroendocrinology and in situ Hybridization, Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, Hungary
| | - Klementina Ocskay
- Laboratory of Neuroendocrinology and in situ Hybridization, Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, Hungary
| | - Klaudia Sípos
- Laboratory of Neuroendocrinology and in situ Hybridization, Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, Hungary
| | - Péter Várnai
- Department of Physiology, Semmelweis University, Budapest, Hungary
| | - Anett Szilvásy-Szabó
- Laboratory of Integrative Neuroendocrinology, Institute of Experimental Medicine, Budapest, Hungary
| | - Csaba Fekete
- Laboratory of Integrative Neuroendocrinology, Institute of Experimental Medicine, Budapest, Hungary
| | - Zsuzsanna E. Tóth
- Laboratory of Neuroendocrinology and in situ Hybridization, Department of Anatomy, Histology and Embryology, Semmelweis University, Budapest, Hungary
- *Correspondence: Zsuzsanna E. Tóth,
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Ulengin-Talkish I, Parson MAH, Jenkins ML, Roy J, Shih AZL, St-Denis N, Gulyas G, Balla T, Gingras AC, Várnai P, Conibear E, Burke JE, Cyert MS. Palmitoylation targets the calcineurin phosphatase to the phosphatidylinositol 4-kinase complex at the plasma membrane. Nat Commun 2021; 12:6064. [PMID: 34663815 PMCID: PMC8523714 DOI: 10.1038/s41467-021-26326-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 09/29/2021] [Indexed: 11/25/2022] Open
Abstract
Calcineurin, the conserved protein phosphatase and target of immunosuppressants, is a critical mediator of Ca2+ signaling. Here, to discover calcineurin-regulated processes we examined an understudied isoform, CNAβ1. We show that unlike canonical cytosolic calcineurin, CNAβ1 localizes to the plasma membrane and Golgi due to palmitoylation of its divergent C-terminal tail, which is reversed by the ABHD17A depalmitoylase. Palmitoylation targets CNAβ1 to a distinct set of membrane-associated interactors including the phosphatidylinositol 4-kinase (PI4KA) complex containing EFR3B, PI4KA, TTC7B and FAM126A. Hydrogen-deuterium exchange reveals multiple calcineurin-PI4KA complex contacts, including a calcineurin-binding peptide motif in the disordered tail of FAM126A, which we establish as a calcineurin substrate. Calcineurin inhibitors decrease PI4P production during Gq-coupled GPCR signaling, suggesting that calcineurin dephosphorylates and promotes PI4KA complex activity. In sum, this work discovers a calcineurin-regulated signaling pathway which highlights the PI4KA complex as a regulatory target and reveals that dynamic palmitoylation confers unique localization, substrate specificity and regulation to CNAβ1.
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Affiliation(s)
| | - Matthew A H Parson
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
| | - Meredith L Jenkins
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
| | - Jagoree Roy
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Alexis Z L Shih
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
- Max-Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Nicole St-Denis
- Lunenfeld-Tanenbaum Research Institute at Mount Sinai Hospital, University of Toronto, Toronto, Canada
- High-Fidelity Science Communications, Summerside, PE, Canada
| | - Gergo Gulyas
- Section on Molecular Signal Transduction, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Tamas Balla
- Section on Molecular Signal Transduction, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Anne-Claude Gingras
- Lunenfeld-Tanenbaum Research Institute at Mount Sinai Hospital, University of Toronto, Toronto, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Péter Várnai
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Elizabeth Conibear
- Department of Medical Genetics, University of British Columbia, Vancouver, Canada
| | - John E Burke
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
- Department of Biochemistry, The University of British Columbia, Vancouver, BC, Canada
| | - Martha S Cyert
- Department of Biology, Stanford University, Stanford, CA, USA.
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10
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Booth DM, Várnai P, Joseph SK, Hajnóczky G. Oxidative bursts of single mitochondria mediate retrograde signaling toward the ER. Mol Cell 2021; 81:3866-3876.e2. [PMID: 34352204 DOI: 10.1016/j.molcel.2021.07.014] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 05/14/2021] [Accepted: 07/13/2021] [Indexed: 10/20/2022]
Abstract
The emerging role of mitochondria as signaling organelles raises the question of whether individual mitochondria can initiate heterotypic communication with neighboring organelles. Using fluorescent probes targeted to the endoplasmic-reticulum-mitochondrial interface, we demonstrate that single mitochondria generate oxidative bursts, rapid redox oscillations, confined to the nanoscale environment of the interorganellar contact sites. Using probes fused to inositol 1,4,5-trisphosphate receptors (IP3Rs), we show that Ca2+ channels directly sense oxidative bursts and respond with Ca2+ transients adjacent to active mitochondria. Application of specific mitochondrial stressors or apoptotic stimuli dramatically increases the frequency and amplitude of the oxidative bursts by enhancing transient permeability transition pore openings. Conversely, blocking interface Ca2+ transport via elimination of IP3Rs or mitochondrial calcium uniporter channels suppresses ER-mitochondrial Ca2+ feedback and cell death. Thus, single mitochondria initiate local retrograde signaling by miniature oxidative bursts and, upon metabolic or apoptotic stress, may also amplify signals to the rest of the cell.
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Affiliation(s)
- David M Booth
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Péter Várnai
- Department of Physiology, Semmelweis University, Faculty of Medicine, 1444 Budapest, Hungary
| | - Suresh K Joseph
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - György Hajnóczky
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA.
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11
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Tóth AD, Garger D, Prokop S, Soltész-Katona E, Várnai P, Balla A, Turu G, Hunyady L. A general method for quantifying ligand binding to unmodified receptors using Gaussia luciferase. J Biol Chem 2021; 296:100366. [PMID: 33545176 PMCID: PMC7950324 DOI: 10.1016/j.jbc.2021.100366] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Revised: 01/27/2021] [Accepted: 02/01/2021] [Indexed: 11/23/2022] Open
Abstract
Reliable measurement of ligand binding to cell surface receptors is of outstanding biological and pharmacological importance. Resonance energy transfer-based assays are powerful approaches to achieve this goal, but the currently available methods are hindered by the necessity of receptor tagging, which can potentially alter ligand binding properties. Therefore, we developed a tag-free system to measure ligand‒receptor interactions in live cells using the Gaussia luciferase (GLuc) as a bioluminescence resonance energy transfer donor. GLuc is as small as the commonly applied Nanoluciferase but has enhanced brightness, and its proper substrate is the frequently used coelenterazine. In our assay, bystander bioluminescence resonance energy transfer is detected between a GLuc-based extracellular surface biosensor and fluorescent ligands bound to their unmodified receptors. The broad spectrum of applications includes equilibrium and kinetic ligand binding measurements for both labeled and competitive unlabeled ligands, and the assay can be utilized for different classes of plasma membrane receptors. Furthermore, the assay is suitable for high-throughput screening, as evidenced by the identification of novel α1 adrenergic receptor ligands. Our data demonstrate that GLuc-based biosensors provide a simple, sensitive, and cost-efficient platform for drug characterization and development.
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Affiliation(s)
- András Dávid Tóth
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary; MTA-SE Laboratory of Molecular Physiology, Eötvös Loránd Research Network, Budapest, Hungary; Department of Internal Medicine and Hematology, Semmelweis University, Budapest, Hungary
| | - Dániel Garger
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Susanne Prokop
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary; Szentágothai János Doctoral School of Neuroscience, Semmelweis University, Budapest, Hungary
| | - Eszter Soltész-Katona
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary; MTA-SE Laboratory of Molecular Physiology, Eötvös Loránd Research Network, Budapest, Hungary
| | - Péter Várnai
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary; MTA-SE Laboratory of Molecular Physiology, Eötvös Loránd Research Network, Budapest, Hungary
| | - András Balla
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary; MTA-SE Laboratory of Molecular Physiology, Eötvös Loránd Research Network, Budapest, Hungary
| | - Gábor Turu
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary; MTA-SE Laboratory of Molecular Physiology, Eötvös Loránd Research Network, Budapest, Hungary
| | - László Hunyady
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary; MTA-SE Laboratory of Molecular Physiology, Eötvös Loránd Research Network, Budapest, Hungary.
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12
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Gulyás G, Sohn M, Kim YJ, Várnai P, Balla T. ORP3 phosphorylation regulates phosphatidylinositol 4-phosphate and Ca 2+ dynamics at plasma membrane-ER contact sites. J Cell Sci 2020; 133:jcs.237388. [PMID: 32041906 DOI: 10.1242/jcs.237388] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 01/29/2020] [Indexed: 12/20/2022] Open
Abstract
Oxysterol-binding protein (OSBP)-related proteins (ORPs) mediate non-vesicular lipid transfer between intracellular membranes. Phosphoinositide (PI) gradients play important roles in the ability of OSBP and some ORPs to transfer cholesterol and phosphatidylserine between the endoplasmic reticulum (ER) and other organelle membranes. Here, we show that plasma membrane (PM) association of ORP3 (also known as OSBPL3), a poorly characterized ORP family member, is triggered by protein kinase C (PKC) activation, especially when combined with Ca2+ increases, and is determined by both PI(4,5)P 2 and PI4P After activation, ORP3 efficiently extracts PI4P and to a lesser extent phosphatidic acid from the PM, and slightly increases PM cholesterol levels. Full activation of ORP3 resulted in decreased PM PI4P levels and inhibited Ca2+ entry via the store-operated Ca2+ entry pathway. The C-terminal region of ORP3 that follows the strictly defined lipid transfer domain was found to be critical for the proper localization and function of the protein.
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Affiliation(s)
- Gergő Gulyás
- 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 Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Mira Sohn
- Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Yeun Ju Kim
- 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
| | - Tamas Balla
- Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
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13
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Tóth JT, Gulyás G, Hunyady L, Várnai P. Development of Nonspecific BRET-Based Biosensors to Monitor Plasma Membrane Inositol Lipids in Living Cells. Methods Mol Biol 2019; 1949:23-34. [PMID: 30790246 DOI: 10.1007/978-1-4939-9136-5_3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
There are several difficulties to face when investigating the role of phosphoinositides. Although they are present in most organelles, their concentration is very low, sometimes undetectable with the available methods; moreover, their level can quickly change upon several external stimuli. Here we introduce a newly improved lipid sensor tool-set based on the balanced expression of luciferase-fused phosphoinositide recognizing protein domains and a Venus protein targeted to the plasma membrane, allowing us to perform Bioluminescence Resonance Energy Transfer (BRET) measurements that reflect phosphoinositide changes in a population of transiently transfected cells. This method is highly sensitive, specific, and capable of semiquantitative characterization of plasma membrane phosphoinositide changes with high temporal resolution.
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Affiliation(s)
- József T Tóth
- Faculty of Medicine, Department of Physiology, Semmelweis University, Budapest, Hungary.,Faculty of Medicine, Department of Anesthesiology and Intensive Therapy, Semmelweis University, Budapest, Hungary
| | - Gergő Gulyás
- Faculty of Medicine, Department of Physiology Semmelweis University, Budapest, Hungary
| | - László Hunyady
- Faculty of Medicine, Department of Physiology, Semmelweis University, Budapest, Hungary.,MTA-SE Laboratory of Molecular Physiology, Budapest, Hungary
| | - Péter Várnai
- Faculty of Medicine, Department of Physiology, Semmelweis University, Budapest, Hungary. .,MTA-SE Laboratory of Molecular Physiology, Budapest, Hungary.
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14
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Gal A, Balicza P, Weaver D, Naghdi S, Joseph SK, Várnai P, Gyuris T, Horváth A, Nagy L, Seifert EL, Molnar MJ, Hajnóczky G. MSTO1 is a cytoplasmic pro-mitochondrial fusion protein, whose mutation induces myopathy and ataxia in humans. EMBO Mol Med 2018; 9:967-984. [PMID: 28554942 PMCID: PMC5494519 DOI: 10.15252/emmm.201607058] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The protein MSTO1 has been localized to mitochondria and linked to mitochondrial morphology, but its specific role has remained unclear. We identified a c.22G > A (p.Val8Met) mutation of MSTO1 in patients with minor physical abnormalities, myopathy, ataxia, and neurodevelopmental impairments. Lactate stress test and myopathological results suggest mitochondrial dysfunction. In patient fibroblasts, MSTO1 mRNA and protein abundance are decreased, mitochondria display fragmentation, aggregation, and decreased network continuity and fusion activity. These characteristics can be reversed by genetic rescue. Short‐term silencing of MSTO1 in HeLa cells reproduced the impairment of mitochondrial morphology and dynamics observed in the fibroblasts without damaging bioenergetics. At variance with a previous report, we find MSTO1 to be localized in the cytoplasmic area with limited colocalization with mitochondria. MSTO1 interacts with the fusion machinery as a soluble factor at the cytoplasm‐mitochondrial outer membrane interface. After plasma membrane permeabilization, MSTO1 is released from the cells. Thus, an MSTO1 loss‐of‐function mutation is associated with a human disorder showing mitochondrial involvement. MSTO1 likely has a physiologically relevant role in mitochondrial morphogenesis by supporting mitochondrial fusion.
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Affiliation(s)
- Aniko Gal
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA.,Institute of Genomic Medicine and Rare Disorders, Semmelweis University, Budapest, Hungary
| | - Peter Balicza
- Institute of Genomic Medicine and Rare Disorders, Semmelweis University, Budapest, Hungary
| | - David Weaver
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Shamim Naghdi
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Suresh K Joseph
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Péter Várnai
- Department of Physiology, Semmelweis University, Budapest, Hungary
| | - Tibor Gyuris
- Department of Biochemistry and Molecular Biology, University of Debrecen, Debrecen, Hungary
| | - Attila Horváth
- Department of Biochemistry and Molecular Biology, University of Debrecen, Debrecen, Hungary
| | - Laszlo Nagy
- Department of Biochemistry and Molecular Biology, University of Debrecen, Debrecen, Hungary
| | - Erin L Seifert
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Maria Judit Molnar
- Institute of Genomic Medicine and Rare Disorders, Semmelweis University, Budapest, Hungary
| | - György Hajnóczky
- MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
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15
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Bagur R, Souza A, Günther G, Reif R, Várnai P, Csordás G, Hajnóczky G. Arsenic Targets Local ROS and Calcium Homeostasis at the Mitochondria-ER Interface. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.3559] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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16
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Tóth AD, Prokop S, Gyombolai P, Várnai P, Balla A, Gurevich VV, Hunyady L, Turu G. Heterologous phosphorylation-induced formation of a stability lock permits regulation of inactive receptors by β-arrestins. J Biol Chem 2017; 293:876-892. [PMID: 29146594 DOI: 10.1074/jbc.m117.813139] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 11/08/2017] [Indexed: 12/24/2022] Open
Abstract
β-Arrestins are key regulators and signal transducers of G protein-coupled receptors (GPCRs). The interaction between receptors and β-arrestins is generally believed to require both receptor activity and phosphorylation by GPCR kinases. In this study, we investigated whether β-arrestins are able to bind second messenger kinase-phosphorylated, but inactive receptors as well. Because heterologous phosphorylation is a common phenomenon among GPCRs, this mode of β-arrestin activation may represent a novel mechanism of signal transduction and receptor cross-talk. Here we demonstrate that activation of protein kinase C (PKC) by phorbol myristate acetate, Gq/11-coupled GPCR, or epidermal growth factor receptor stimulation promotes β-arrestin2 recruitment to unliganded AT1 angiotensin receptor (AT1R). We found that this interaction depends on the stability lock, a structure responsible for the sustained binding between GPCRs and β-arrestins, formed by phosphorylated serine-threonine clusters in the receptor's C terminus and two conserved phosphate-binding lysines in the β-arrestin2 N-domain. Using improved FlAsH-based serine-threonine clusters β-arrestin2 conformational biosensors, we also show that the stability lock not only stabilizes the receptor-β-arrestin interaction, but also governs the structural rearrangements within β-arrestins. Furthermore, we found that β-arrestin2 binds to PKC-phosphorylated AT1R in a distinct active conformation, which triggers MAPK recruitment and receptor internalization. Our results provide new insights into the activation of β-arrestins and reveal their novel role in receptor cross-talk.
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Affiliation(s)
- András D Tóth
- From the Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest H-1094, Hungary
| | - Susanne Prokop
- From the Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest H-1094, Hungary
| | - Pál Gyombolai
- From the Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest H-1094, Hungary.,the MTA-SE Laboratory of Molecular Physiology, Hungarian Academy of Sciences and Semmelweis University, Budapest H-1094, Hungary, and
| | - Péter Várnai
- From the Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest H-1094, Hungary.,the MTA-SE Laboratory of Molecular Physiology, Hungarian Academy of Sciences and Semmelweis University, Budapest H-1094, Hungary, and
| | - András Balla
- From the Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest H-1094, Hungary.,the MTA-SE Laboratory of Molecular Physiology, Hungarian Academy of Sciences and Semmelweis University, Budapest H-1094, Hungary, and
| | - Vsevolod V Gurevich
- the Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232
| | - László Hunyady
- From the Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest H-1094, Hungary, .,the MTA-SE Laboratory of Molecular Physiology, Hungarian Academy of Sciences and Semmelweis University, Budapest H-1094, Hungary, and
| | - Gábor Turu
- From the Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest H-1094, Hungary.,the MTA-SE Laboratory of Molecular Physiology, Hungarian Academy of Sciences and Semmelweis University, Budapest H-1094, Hungary, and
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17
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Gulyás G, Radvánszki G, Matuska R, Balla A, Hunyady L, Balla T, Várnai P. Plasma membrane phosphatidylinositol 4-phosphate and 4,5-bisphosphate determine the distribution and function of K-Ras4B but not H-Ras proteins. J Biol Chem 2017; 292:18862-18877. [PMID: 28939768 DOI: 10.1074/jbc.m117.806679] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/11/2017] [Indexed: 11/06/2022] Open
Abstract
Plasma membrane (PM) localization of Ras proteins is crucial for transmitting signals upon mitogen stimulation. Post-translational lipid modification of Ras proteins plays an important role in their recruitment to the PM. Electrostatic interactions between negatively charged PM phospholipids and basic amino acids found in K-Ras4B (K-Ras) but not in H-Ras are important for permanent K-Ras localization to the PM. Here, we investigated how acute depletion of negatively charged PM polyphosphoinositides (PPIns) from the PM alters the intracellular distribution and activity of K- and H-Ras proteins. PPIns depletion from the PM was achieved either by agonist-induced activation of phospholipase C β or with a rapamycin-inducible system in which various phosphatidylinositol phosphatases were recruited to the PM. Redistribution of the two Ras proteins was monitored with confocal microscopy or with a recently developed bioluminescence resonance energy transfer-based approach involving fusion of the Ras C-terminal targeting sequences or the entire Ras proteins to Venus fluorescent protein. We found that PM PPIns depletion caused rapid translocation of K-Ras but not H-Ras from the PM to the Golgi. PM depletion of either phosphatidylinositol 4-phosphate (PtdIns4P) or PtdIns(4,5)P2 but not PtdIns(3,4,5)P3 was sufficient to evoke K-Ras translocation. This effect was diminished by deltarasin, an inhibitor of the Ras-phosphodiesterase interaction, or by simultaneous depletion of the Golgi PtdIns4P. The PPIns depletion decreased incorporation of [3H]leucine in K-Ras-expressing cells, suggesting that Golgi-localized K-Ras is not as signaling-competent as its PM-bound form. We conclude that PPIns in the PM are important regulators of K-Ras-mediated signals.
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Affiliation(s)
- Gergő Gulyás
- From the Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest 1094, Hungary
| | - Glória Radvánszki
- From the Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest 1094, Hungary
| | - Rita Matuska
- From the Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest 1094, Hungary
| | - András Balla
- From the Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest 1094, Hungary.,MTA-SE Laboratory of Molecular Physiology, Hungarian Academy of Sciences and Semmelweis University, Budapest 1094, Hungary, and
| | - László Hunyady
- From the Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest 1094, Hungary.,MTA-SE Laboratory of Molecular Physiology, Hungarian Academy of Sciences and Semmelweis University, Budapest 1094, Hungary, and
| | - Tamas Balla
- Section on Molecular Signal Transduction, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892
| | - Péter Várnai
- From the Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest 1094, Hungary,
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18
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Tóth AD, Gyombolai P, Szalai B, Várnai P, Turu G, Hunyady L. Angiotensin type 1A receptor regulates β-arrestin binding of the β 2-adrenergic receptor via heterodimerization. Mol Cell Endocrinol 2017; 442:113-124. [PMID: 27908837 DOI: 10.1016/j.mce.2016.11.027] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 10/26/2016] [Accepted: 11/26/2016] [Indexed: 02/06/2023]
Abstract
Heterodimerization between angiotensin type 1A receptor (AT1R) and β2-adrenergic receptor (β2AR) has been shown to modulate G protein-mediated effects of these receptors. Activation of G protein-coupled receptors (GPCRs) leads to β-arrestin binding, desensitization, internalization and G protein-independent signaling of GPCRs. Our aim was to study the effect of heterodimerization on β-arrestin coupling. We found that β-arrestin binding of β2AR is affected by activation of AT1Rs. Costimulation with angiotensin II and isoproterenol markedly enhanced the interaction between β2AR and β-arrestins, by prolonging the lifespan of β2AR-induced β-arrestin2 clusters at the plasma membrane. While candesartan, a conventional AT1R antagonist, had no effect on the β-arrestin2 binding to β2AR, TRV120023, a β-arrestin biased agonist, enhanced the interaction. These findings reveal a new crosstalk mechanism between AT1R and β2AR, and suggest that enhanced β-arrestin2 binding to β2AR can contribute to the pharmacological effects of biased AT1R agonists.
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Affiliation(s)
- András D Tóth
- Department of Physiology, Faculty of Medicine, Semmelweis University, P. O. Box 2, H-1428 Budapest, Hungary
| | - Pál Gyombolai
- Department of Physiology, Faculty of Medicine, Semmelweis University, P. O. Box 2, H-1428 Budapest, Hungary; MTA-SE Laboratory of Molecular Physiology, Hungarian Academy of Sciences and Semmelweis University, Budapest, Hungary
| | - Bence Szalai
- Department of Physiology, Faculty of Medicine, Semmelweis University, P. O. Box 2, H-1428 Budapest, Hungary; MTA-SE Laboratory of Molecular Physiology, Hungarian Academy of Sciences and Semmelweis University, Budapest, Hungary
| | - Péter Várnai
- Department of Physiology, Faculty of Medicine, Semmelweis University, P. O. Box 2, H-1428 Budapest, Hungary
| | - Gábor Turu
- Department of Physiology, Faculty of Medicine, Semmelweis University, P. O. Box 2, H-1428 Budapest, Hungary; MTA-SE Laboratory of Molecular Physiology, Hungarian Academy of Sciences and Semmelweis University, Budapest, Hungary
| | - László Hunyady
- Department of Physiology, Faculty of Medicine, Semmelweis University, P. O. Box 2, H-1428 Budapest, Hungary; MTA-SE Laboratory of Molecular Physiology, Hungarian Academy of Sciences and Semmelweis University, Budapest, Hungary.
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19
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Várnai P, Gulyás G, Tóth DJ, Sohn M, Sengupta N, Balla T. Quantifying lipid changes in various membrane compartments using lipid binding protein domains. Cell Calcium 2016; 64:72-82. [PMID: 28088320 DOI: 10.1016/j.ceca.2016.12.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 12/28/2016] [Accepted: 12/29/2016] [Indexed: 11/30/2022]
Abstract
One of the largest challenges in cell biology is to map the lipid composition of the membranes of various organelles and define the exact location of processes that control the synthesis and distribution of lipids between cellular compartments. The critical role of phosphoinositides, low-abundant lipids with rapid metabolism and exceptional regulatory importance in the control of almost all aspects of cellular functions created the need for tools to visualize their localizations and dynamics at the single cell level. However, there is also an increasing need for methods to determine the cellular distribution of other lipids regulatory or structural, such as diacylglycerol, phosphatidic acid, or other phospholipids and cholesterol. This review will summarize recent advances in this research field focusing on the means by which changes can be described in more quantitative terms.
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Affiliation(s)
- Péter Várnai
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Gergő Gulyás
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Dániel J Tóth
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, United States; Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Mira Sohn
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, United States
| | - Nivedita Sengupta
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, United States
| | - Tamas Balla
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, United States.
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20
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Gulyás G, Tóth JT, Tóth DJ, Kurucz I, Hunyady L, Balla T, Várnai P. Measurement of inositol 1,4,5-trisphosphate in living cells using an improved set of resonance energy transfer-based biosensors. PLoS One 2015; 10:e0125601. [PMID: 25932648 PMCID: PMC4416922 DOI: 10.1371/journal.pone.0125601] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 03/24/2015] [Indexed: 01/22/2023] Open
Abstract
Improved versions of inositol-1,4,5-trisphosphate (InsP3) sensors were created to follow intracellular InsP3 changes in single living cells and in cell populations. Similar to previous InsP3 sensors the new sensors are based on the ligand binding domain of the human type-I InsP3 receptor (InsP3R-LBD), but contain a mutation of either R265K or R269K to lower their InsP3 binding affinity. Tagging the InsP3R-LBD with N-terminal Cerulean and C-terminal Venus allowed measurement of InsP3 in single-cell FRET experiments. Replacing Cerulean with a Luciferase enzyme allowed experiments in multi-cell format by measuring the change in the BRET signal upon stimulation. These sensors faithfully followed the agonist-induced increase in InsP3 concentration in HEK 293T cells expressing the Gq-coupled AT1 angiotensin receptor detecting a response to agonist concentration as low as 10 pmol/L. Compared to the wild type InsP3 sensor, the mutant sensors showed an improved off-rate, enabling a more rapid and complete return of the signal to the resting value of InsP3 after termination of M3 muscarinic receptor stimulation by atropine. For parallel measurements of intracellular InsP3 and Ca2+ levels in BRET experiments, the Cameleon D3 Ca2+ sensor was modified by replacing its CFP with luciferase. In these experiments depletion of plasma membrane PtdIns(4,5)P2 resulted in the fall of InsP3 level, followed by the decrease of the Ca2+-signal evoked by the stimulation of the AT1 receptor. In contrast, when type-III PI 4-kinases were inhibited with a high concentration of wortmannin or a more specific inhibitor, A1, the decrease of the Ca2+-signal preceded the fall of InsP3 level indicating an InsP3-, independent, direct regulation of capacitative Ca2+ influx by plasma membrane inositol lipids. Taken together, our results indicate that the improved InsP3 sensor can be used to monitor both the increase and decrease of InsP3 levels in live cells suitable for high-throughput BRET applications.
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Affiliation(s)
- Gergő Gulyás
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest 1094, Hungary
| | - József T. Tóth
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest 1094, Hungary
| | - Dániel J. Tóth
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest 1094, Hungary
| | - István Kurucz
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, United States of America
| | - László Hunyady
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest 1094, Hungary
| | - Tamas Balla
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, United States of America
| | - Péter Várnai
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest 1094, Hungary
- * E-mail:
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22
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Erdélyi L, Mann A, Várnai P, Balla A, Hunyady L. Characterization of the Inherited I130N Substitution in V2 Vasopressin Receptor Revealed a Gain‐of‐Function Mutation Leading to NSIAD. FASEB J 2015. [DOI: 10.1096/fasebj.29.1_supplement.809.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- László Erdélyi
- Department of PhysiologySemmelweis UniversityBudapestHungary
- MTA‐SE Laboratory of Molecular Physiology Hungarian Academy of Sciences and Semmelweis UniversityBudapestHungary
| | | | - Péter Várnai
- Department of PhysiologySemmelweis UniversityBudapestHungary
- MTA‐SE Laboratory of Molecular Physiology Hungarian Academy of Sciences and Semmelweis UniversityBudapestHungary
| | - András Balla
- MTA‐SE Laboratory of Molecular Physiology Hungarian Academy of Sciences and Semmelweis UniversityBudapestHungary
| | - László Hunyady
- Department of PhysiologySemmelweis UniversityBudapestHungary
- MTA‐SE Laboratory of Molecular Physiology Hungarian Academy of Sciences and Semmelweis UniversityBudapestHungary
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23
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Szakadáti G, Tóth AD, Oláh I, Erdélyi LS, Balla T, Várnai P, Hunyady L, Balla A. Investigation of the fate of type I angiotensin receptor after biased activation. Mol Pharmacol 2015; 87:972-81. [PMID: 25804845 DOI: 10.1124/mol.114.097030] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 03/24/2015] [Indexed: 01/14/2023] Open
Abstract
Biased agonism on the type I angiotensin receptor (AT1-R) can achieve different outcomes via activation of G protein-dependent and -independent cellular responses. In this study, we investigated whether the biased activation of AT1-R can lead to different regulation and intracellular processing of the receptor. We analyzed β-arrestin binding, endocytosis, and subsequent trafficking steps, such as early and late phases of recycling of AT1-R in human embryonic kidney 293 cells expressing wild-type or biased mutant receptors in response to different ligands. We used Renilla luciferase-tagged receptors and yellow fluorescent protein-tagged β-arrestin2, Rab5, Rab7, and Rab11 proteins in bioluminescence resonance energy transfer measurements to follow the fate of the receptor after stimulation. We found that not only is the signaling of the receptor different upon using selective ligands, but the fate within the cells is also determined by the type of the stimulation. β-arrestin binding and the internalization kinetics of the angiotensin II-stimulated AT1-R differed from those stimulated by the biased agonists. Similarly, angiotensin II-stimulated wild-type AT1-R showed differences compared with a biased mutant AT1-R (DRY/AAY AT1-R) with regards to β-arrestin binding and endocytosis. We found that the differences in the internalization kinetics of the receptor in response to biased agonist stimulation are due to the differences in plasma membrane phosphatidylinositol 4,5-bisphosphate depletion. Moreover, the stability of the β-arrestin binding is a major determinant of the later fate of the internalized AT1-R receptor.
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Affiliation(s)
- Gyöngyi Szakadáti
- Department of Physiology, Semmelweis University, Faculty of Medicine, Budapest, Hungary (G.S., A.D.T., I.O., L.S.E., P.V., L.H., A.B.), Magyar Tudományos Akadémia-Semmelweis Egyetem Laboratory of Molecular Physiology, Hungarian Academy of Sciences and Semmelweis University, Budapest, Hungary (L.S.E., P.V., L.H., A.B.); and Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (T.B.)
| | - András D Tóth
- Department of Physiology, Semmelweis University, Faculty of Medicine, Budapest, Hungary (G.S., A.D.T., I.O., L.S.E., P.V., L.H., A.B.), Magyar Tudományos Akadémia-Semmelweis Egyetem Laboratory of Molecular Physiology, Hungarian Academy of Sciences and Semmelweis University, Budapest, Hungary (L.S.E., P.V., L.H., A.B.); and Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (T.B.)
| | - Ilona Oláh
- Department of Physiology, Semmelweis University, Faculty of Medicine, Budapest, Hungary (G.S., A.D.T., I.O., L.S.E., P.V., L.H., A.B.), Magyar Tudományos Akadémia-Semmelweis Egyetem Laboratory of Molecular Physiology, Hungarian Academy of Sciences and Semmelweis University, Budapest, Hungary (L.S.E., P.V., L.H., A.B.); and Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (T.B.)
| | - László Sándor Erdélyi
- Department of Physiology, Semmelweis University, Faculty of Medicine, Budapest, Hungary (G.S., A.D.T., I.O., L.S.E., P.V., L.H., A.B.), Magyar Tudományos Akadémia-Semmelweis Egyetem Laboratory of Molecular Physiology, Hungarian Academy of Sciences and Semmelweis University, Budapest, Hungary (L.S.E., P.V., L.H., A.B.); and Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (T.B.)
| | - Tamas Balla
- Department of Physiology, Semmelweis University, Faculty of Medicine, Budapest, Hungary (G.S., A.D.T., I.O., L.S.E., P.V., L.H., A.B.), Magyar Tudományos Akadémia-Semmelweis Egyetem Laboratory of Molecular Physiology, Hungarian Academy of Sciences and Semmelweis University, Budapest, Hungary (L.S.E., P.V., L.H., A.B.); and Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (T.B.)
| | - Péter Várnai
- Department of Physiology, Semmelweis University, Faculty of Medicine, Budapest, Hungary (G.S., A.D.T., I.O., L.S.E., P.V., L.H., A.B.), Magyar Tudományos Akadémia-Semmelweis Egyetem Laboratory of Molecular Physiology, Hungarian Academy of Sciences and Semmelweis University, Budapest, Hungary (L.S.E., P.V., L.H., A.B.); and Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (T.B.)
| | - László Hunyady
- Department of Physiology, Semmelweis University, Faculty of Medicine, Budapest, Hungary (G.S., A.D.T., I.O., L.S.E., P.V., L.H., A.B.), Magyar Tudományos Akadémia-Semmelweis Egyetem Laboratory of Molecular Physiology, Hungarian Academy of Sciences and Semmelweis University, Budapest, Hungary (L.S.E., P.V., L.H., A.B.); and Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (T.B.)
| | - András Balla
- Department of Physiology, Semmelweis University, Faculty of Medicine, Budapest, Hungary (G.S., A.D.T., I.O., L.S.E., P.V., L.H., A.B.), Magyar Tudományos Akadémia-Semmelweis Egyetem Laboratory of Molecular Physiology, Hungarian Academy of Sciences and Semmelweis University, Budapest, Hungary (L.S.E., P.V., L.H., A.B.); and Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (T.B.)
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24
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Booth DM, Enyedi B, Geiszt M, Várnai P, Hajnóczky G. ER Calcium Release is Tuned by Mitochondrial Redox Nanodomains. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.3319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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25
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Szalai B, Hoffmann P, Prokop S, Erdélyi L, Várnai P, Hunyady L. Improved methodical approach for quantitative BRET analysis of G Protein Coupled Receptor dimerization. PLoS One 2014; 9:e109503. [PMID: 25329164 PMCID: PMC4201472 DOI: 10.1371/journal.pone.0109503] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 09/11/2014] [Indexed: 01/22/2023] Open
Abstract
G Protein Coupled Receptors (GPCR) can form dimers or higher ordered oligomers, the process of which can remarkably influence the physiological and pharmacological function of these receptors. Quantitative Bioluminescence Resonance Energy Transfer (qBRET) measurements are the gold standards to prove the direct physical interaction between the protomers of presumed GPCR dimers. For the correct interpretation of these experiments, the expression of the energy donor Renilla luciferase labeled receptor has to be maintained constant, which is hard to achieve in expression systems. To analyze the effects of non-constant donor expression on qBRET curves, we performed Monte Carlo simulations. Our results show that the decrease of donor expression can lead to saturation qBRET curves even if the interaction between donor and acceptor labeled receptors is non-specific leading to false interpretation of the dimerization state. We suggest here a new approach to the analysis of qBRET data, when the BRET ratio is plotted as a function of the acceptor labeled receptor expression at various donor receptor expression levels. With this method, we were able to distinguish between dimerization and non-specific interaction when the results of classical qBRET experiments were ambiguous. The simulation results were confirmed experimentally using rapamycin inducible heterodimerization system. We used this new method to investigate the dimerization of various GPCRs, and our data have confirmed the homodimerization of V2 vasopressin and CaSR calcium sensing receptors, whereas our data argue against the heterodimerization of these receptors with other studied GPCRs, including type I and II angiotensin, β2 adrenergic and CB1 cannabinoid receptors.
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Affiliation(s)
- Bence Szalai
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
- MTA-SE Laboratory of Molecular Physiology, Budapest, Hungary
| | - Péter Hoffmann
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - Susanne Prokop
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
| | - László Erdélyi
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
- MTA-SE Laboratory of Molecular Physiology, Budapest, Hungary
| | - Péter Várnai
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
- MTA-SE Laboratory of Molecular Physiology, Budapest, Hungary
| | - László Hunyady
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
- MTA-SE Laboratory of Molecular Physiology, Budapest, Hungary
- * E-mail:
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26
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Erdélyi LS, Balla A, Patócs A, Tóth M, Várnai P, Hunyady L. Altered agonist sensitivity of a mutant v2 receptor suggests a novel therapeutic strategy for nephrogenic diabetes insipidus. Mol Endocrinol 2014; 28:634-43. [PMID: 24628417 DOI: 10.1210/me.2013-1424] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Loss-of-function mutations of the type 2 vasopressin receptor (V2R) in kidney can lead to nephrogenic diabetes insipidus (NDI). We studied a previously described, but uncharacterized, mutation of the V2R (N321K missense mutation) of a patient with NDI. The properties of the mutant receptor were evaluated. We constructed a highly sensitive Epac-based bioluminescence resonance energy transfer biosensor to perform real-time cAMP measurements after agonist stimulation of transiently transfected HEK293 cells with V2Rs. β-Arrestin binding of the activated receptors was examined with luciferase-tagged β-arrestin and mVenus-tagged V2Rs using the bioluminescence resonance energy transfer technique. Cell surface expression levels of hemagglutinin-tagged receptors were determined with flow cytometry using anti-hemagglutinin-Alexa 488 antibodies. Cellular localization examinations were implemented with fluorescent tagged receptors visualized with confocal laser scanning microscopy. The effect of various vasopressin analogs on the type 1 vasopressin receptor (V1R) was tested on mouse arteries by wire myography. The N321K mutant V2R showed normal cell surface expression, but the potency of arginine vasopressin for cAMP generation was low, whereas the clinically used desmopressin was not efficient. The β-arrestin binding and internalization properties of the mutant receptor were also different than those for the wild type. The function of the mutant receptor can be rescued with administration of the V2R agonist Val(4)-desmopressin, which had no detectable side effects on V1R in the effective cAMP generating concentrations. Based on these findings we propose a therapeutic strategy for patients with NDI carrying the N321K mutation, as our in vivo experiments suggest that Val(4)-desmopressin could rescue the function of the N321K-V2R without significant side effects on the V1R.
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Affiliation(s)
- László Sándor Erdélyi
- Department of Physiology (L.S.E., A.B., P.V., L.H.), Faculty of Medicine, Semmelweis University, H-1094 Budapest, Hungary; MTA-SE Laboratory of Molecular Physiology (L.S.E., A.B., V.P., L.H.), Hungarian Academy of Sciences and Semmelweis University, H-1094 Budapest, Hungary; 2nd Department of Internal Medicine (A.P., M.T.), Faculty of Medicine, Semmelweis University, H-1094 Budapest, Hungary
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27
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Booth DM, Enyedi B, Geiszt M, Várnai P, Hajnóczky G. Calcium-Induced Redox Microdimains at the ER-Mitochondrial Interface. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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28
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Tóth DJ, Tóth JT, Tallósy B, Hunyady L, Várnai P. The Effect of Phosphatidylinositol 4,5‐bisphosphate Depletion on the Internalization of G Protein‐coupled Receptors. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.1050.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Dániel J Tóth
- Department of PhysiologyFaculty of MedicineSemmelweis UniversityBudapestHungary
- Laboratory of Molecular PhysiologyHungarian Academy of Sciences and Semmelweis UniversityBudapestHungary
| | - József T Tóth
- Department of PhysiologyFaculty of MedicineSemmelweis UniversityBudapestHungary
| | - Bernadett Tallósy
- Department of PhysiologyFaculty of MedicineSemmelweis UniversityBudapestHungary
| | - László Hunyady
- Department of PhysiologyFaculty of MedicineSemmelweis UniversityBudapestHungary
- Laboratory of Molecular PhysiologyHungarian Academy of Sciences and Semmelweis UniversityBudapestHungary
| | - Péter Várnai
- Department of PhysiologyFaculty of MedicineSemmelweis UniversityBudapestHungary
- Laboratory of Molecular PhysiologyHungarian Academy of Sciences and Semmelweis UniversityBudapestHungary
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29
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Lamport DTA, Várnai P. Periplasmic arabinogalactan glycoproteins act as a calcium capacitor that regulates plant growth and development. New Phytol 2013; 197:58-64. [PMID: 23106282 DOI: 10.1111/nph.12005] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 09/15/2012] [Indexed: 05/18/2023]
Abstract
Arabinogalactan glycoproteins (AGPs) are implicated in virtually all aspects of plant growth and development, yet their precise role remains unknown. Classical AGPs cover the plasma membrane and are highly glycosylated by numerous acidic arabinogalactan polysaccharides O-linked to hydroxyproline. Their heterogeneity and complexity hindered a structural approach until the recent determination of a highly conserved repetitive consensus structure for a 15-sugar residue arabinogalactan subunit with paired glucuronic carboxyls. Based on NMR data and molecular dynamics simulations, we identify these carboxyls as potential intramolecular Ca(2+)-binding sites. Using rapid ultrafiltration assays and mass spectrometry, we verified that AGPs bind Ca(2+) tightly (K(d) ~ 6.5 μM) and stoichiometrically at pH 5. Ca(2+) binding is reversible in a pH-dependent manner. As typical AGPs contain c. 30 Ca(2+)-binding subunits and are bulk components of the periplasm, they represent a Ca(2+) capacitor discharged at low pH by stretch-activated plasma membrane H(+)-ATPases, hence a substantial source of cytosolic Ca(2+). We propose that these Ca(2+) waves prime the 'calcium oscillator', a signal generator essential to the global Ca(2+) signalling pathway of green plants.
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Affiliation(s)
- Derek T A Lamport
- School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9QG, UK
| | - Péter Várnai
- School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9QG, UK
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30
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Booth DM, Enyedi B, Geiszt M, Várnai P, Hajnóczky G. Dynamic Measurement of Ca2+-Induced Changes in Organelle-Specific Redox Microdomains. Biophys J 2013. [DOI: 10.1016/j.bpj.2012.11.1220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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31
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Yi M, Weaver D, Eisner V, Várnai P, Hunyady L, Ma J, Csordás G, Hajnóczky G. Switch from ER-mitochondrial to SR-mitochondrial calcium coupling during muscle differentiation. Cell Calcium 2012; 52:355-65. [PMID: 22784666 DOI: 10.1016/j.ceca.2012.05.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 05/25/2012] [Accepted: 05/28/2012] [Indexed: 11/26/2022]
Abstract
Emerging evidence indicates that mitochondria are locally coupled to endoplasmic reticulum (ER) Ca2+ release in myoblasts and to sarcoplasmic reticulum (SR) Ca2+ release in differentiated muscle fibers in order to regulate cytoplasmic calcium dynamics and match metabolism with cell activity. However, the mechanism of the developmental transition from ER to SR coupling remains unclear. We have studied mitochondrial sensing of IP3 receptor (IP3R)- and ryanodine receptor (RyR)-mediated Ca2+ signals in H9c2 myoblasts and differentiating myotubes, as well as the attendant changes in mitochondrial morphology. Mitochondria in myoblasts were largely elongated, luminally connected and relatively few in number, whereas the myotubes were densely packed with globular mitochondria that displayed limited luminal continuity. Vasopressin, an IP3-linked agonist, evoked a large cytoplasmic Ca2+ ([Ca2+]c) increase in myoblasts, whereas it elicited a smaller response in myotubes. Conversely, RyR-mediated Ca2+ release induced by caffeine, was not observed in myoblasts, but triggered a large [Ca2+]c signal in myotubes. Both the IP3R and the RyR-mediated [Ca2+]c rise was closely associated with a mitochondrial matrix Ca2+ ([Ca2+]m) signal. Every myotube that showed a [Ca2+]c spike also displayed a [Ca2+]m response. Addition of IP3 to permeabilized myoblasts and caffeine to permeabilized myotubes also resulted in a rapid [Ca2+]m rise, indicating that Ca2+ was delivered via local coupling of the ER/SR and mitochondria. Thus, as RyRs are expressed during muscle differentiation, the local connection between RyR and mitochondrial Ca2+ uptake sites also appears. When RyR1 was exogenously introduced to myoblasts by overexpression, the [Ca2+]m signal appeared together with the [Ca2+]c signal, however the mitochondrial morphology remained unchanged. Thus, RyR expression alone is sufficient to induce the steps essential for their alignment with mitochondrial Ca2+ uptake sites, whereas the mitochondrial proliferation and reshaping utilize either downstream or alternative pathways.
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Affiliation(s)
- Muqing Yi
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
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Tóth DJ, Tóth J, Gulyás G, Balla A, Balla T, Hunyady L, Várnai P. Acute depletion of plasma membrane phosphatidylinositol 4,5-bisphosphate impairs specific steps in endocytosis of the G-protein-coupled receptor. J Cell Sci 2012. [DOI: 10.1242/jcs.115048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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33
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Szalai B, Barkai L, Turu G, Szidonya L, Várnai P, Hunyady L. Allosteric interactions within the AT₁ angiotensin receptor homodimer: role of the conserved DRY motif. Biochem Pharmacol 2012; 84:477-85. [PMID: 22579851 DOI: 10.1016/j.bcp.2012.04.014] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 04/15/2012] [Accepted: 04/18/2012] [Indexed: 12/20/2022]
Abstract
G protein coupled receptor (GPCR) dimerization has a remarkable impact on the diversity of receptor signaling. Allosteric communication between the protomers of the dimer can alter ligand binding, receptor conformation and interactions with different effector proteins. In this study we investigated the allosteric interactions between wild type and mutant protomers of type 1 angiotensin receptor (AT₁R) dimers transiently expressed in CHO cells. In our experimental setup, one protomer of the dimer was selectively stimulated and the β-arrestin2 binding and conformation alteration of the other protomer was followed. The interaction between β-arrestin2 and the non-stimulated protomer was monitored through a bioluminescence resonance energy transfer (BRET) based method. To measure the conformational alterations in the non-stimulated protomer directly, we also used a BRET based intramolecular receptor biosensor, which was created by inserting yellow fluorescent protein (YFP) into the 3rd intracellular loop of AT₁R and fusing Renilla luciferase (RLuc) to its C terminal region. We have detected β-arrestin2 binding, and altered conformation of the non-stimulated protomer. The cooperative ligand binding of the receptor homodimer was also observed by radioligand dissociation experiments. Mutation of the conserved DRY sequence in the activated protomer, which is also required for G protein activation, abolished all the observed allosteric effects. These data suggest that allosteric interactions in the homodimers of AT₁R significantly affect the function of the non-stimulated protomer, and the conserved DRY motif has a crucial role in these interactions.
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Affiliation(s)
- Bence Szalai
- Department of Physiology, Semmelweis University, Faculty of Medicine, Budapest, Hungary
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Hunyady L, Soltész-Katona E, Várnai P, Balla A. Study of the Compartmentalization of Type 1 Angiotensin Receptor Using Bioluminescence Resonance Energy Transfer‐based Sensors. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.lb174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- László Hunyady
- Department of PhysiologySemmelweis UniversityBudapestHungary
| | | | - Péter Várnai
- Department of PhysiologySemmelweis UniversityBudapestHungary
| | - András Balla
- Department of PhysiologySemmelweis UniversityBudapestHungary
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Tóth DJ, Tóth JT, Gulyás G, Balla A, Balla T, Hunyady L, Várnai P. Acute depletion of plasma membrane phosphatidylinositol 4,5-bisphosphate impairs specific steps in endocytosis of the G-protein-coupled receptor. J Cell Sci 2012; 125:2185-97. [PMID: 22357943 DOI: 10.1242/jcs.097279] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Receptor endocytosis plays an important role in regulating the responsiveness of cells to specific ligands. Phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P(2)] has been shown to be crucial for endocytosis of some cell surface receptors, such as EGF and transferrin receptors, but its role in G-protein-coupled receptor internalization has not been investigated. By using luciferase-labeled type 1 angiotensin II (AT1R), type 2C serotonin (5HT2CR) or β(2) adrenergic (β2AR) receptors and fluorescently tagged proteins (β-arrestin-2, plasma-membrane-targeted Venus, Rab5) we were able to follow the sequence of molecular interactions along the endocytic route of the receptors in HEK293 cells using the highly sensitive method of bioluminescence resonance energy transfer and confocal microscopy. To study the role of plasma membrane PtdIns(4,5)P(2) in receptor endocytosis, we used our previously developed rapamycin-inducible heterodimerization system, in which the recruitment of a 5-phosphatase domain to the plasma membrane degrades PtdIns(4,5)P(2). Here we show that ligand-induced interaction of AT1, 5HT2C and β(2)A receptors with β-arrestin-2 was unaffected by PtdIns(4,5)P(2) depletion. However, trafficking of the receptors to Rab5-positive early endosomes was completely abolished in the absence of PtdIns(4,5)P(2). Remarkably, removal of the receptors from the plasma membrane was reduced but not eliminated after PtdIns(4,5)P(2) depletion. Under these conditions, stimulated AT1 receptors clustered along the plasma membrane, but did not enter the cells. Our data suggest that in the absence of PtdIns(4,5)P(2), these receptors move into clathrin-coated membrane structures, but these are not cleaved efficiently and hence cannot reach the early endosomal compartment.
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Affiliation(s)
- Dániel J Tóth
- Department of Physiology, Semmelweis University, Faculty of Medicine, Budapest, Hungary
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36
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Balla A, Tóth DJ, Soltész-Katona E, Szakadáti G, Erdélyi LS, Várnai P, Hunyady L. Mapping of the localization of type 1 angiotensin receptor in membrane microdomains using bioluminescence resonance energy transfer-based sensors. J Biol Chem 2012; 287:9090-9. [PMID: 22291018 DOI: 10.1074/jbc.m111.293944] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Initiation and termination of signaling of the type I angiotensin receptor (AT(1)-R) can lead to dynamic changes in its localization in plasma membrane microdomains. Several markers were recently developed to investigate membrane microdomains. Here, we used several YFP-labeled fusion constructs (i.e. raft or non-raft plasma membrane markers) to analyze the agonist-induced changes in compartmentalization of AT(1)-R, including internalization or lateral movement between plasma membrane compartments in response to stimulation using bioluminescence resonance energy transfer measurements. Our data demonstrate that angiotensin II (AngII) stimulus changes the microdomain localization of wild type or mutated (DRY → AAY or TSTS → AAAA) AT(1)-Rs co-expressed with the fluorescent probes in HEK293 cells. The comparison of the trafficking of AT(1)-R upon AngII stimulus with those of [Sar(1),Ile(8)]AngII or [Sar(1),Ile(4),Ile(8)]AngII stimulus revealed different types of changes, depending on the nature of the ligand. The observed changes in receptor compartmentalization of the AT(1)-R are strikingly different from those of 5HT-2C and EGF receptors, which demonstrate the usefulness of the bioluminescence resonance energy transfer-based measurements in the investigation of receptor trafficking in the plasma membrane in living cell experiments.
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Affiliation(s)
- András Balla
- Department of Physiology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
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37
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Abstract
The dynamin-related GTPase protein OPA1, localized in the intermembrane space and tethered to the inner membrane of mitochondria, participates in the fusion of these organelles. Its mutation is the most prevalent cause of Autosomal Dominant Optic Atrophy. OPA1 controls the diameter of the junctions between the boundary part of the inner membrane and the membrane of cristae and reduces the diffusibility of cytochrome c through these junctions. We postulated that if significant Ca²⁺ uptake into the matrix occurs from the lumen of the cristae, reduced expression of OPA1 would increase the access of Ca²⁺ to the transporters in the crista membrane and thus would enhance Ca²⁺ uptake. In intact H295R adrenocortical and HeLa cells cytosolic Ca²⁺ signals evoked with K⁺ and histamine, respectively, were transferred into the mitochondria. The rate and amplitude of mitochondrial [Ca²⁺] rise (followed with confocal laser scanning microscopy and FRET measurements with fluorescent wide-field microscopy) were increased after knockdown of OPA1, as compared with cells transfected with control RNA or mitofusin1 siRNA. Ca²⁺ uptake was enhanced despite reduced mitochondrial membrane potential. In permeabilized cells the rate of Ca²⁺ uptake by depolarized mitochondria was also increased in OPA1-silenced cells. The participation of Na⁺/Ca²⁺ and Ca²⁺/H⁺ antiporters in this transport process is indicated by pharmacological data. Altogether, our observations reveal the significance of OPA1 in the control of mitochondrial Ca²⁺ metabolism.
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Affiliation(s)
- László Fülöp
- Department of Physiology, Faculty of Medicine, Semmelweis University, Hungarian Academy of Sciences, Budapest, Hungary
| | - Gergö Szanda
- Department of Physiology, Faculty of Medicine, Semmelweis University, Hungarian Academy of Sciences, Budapest, Hungary
| | - Balázs Enyedi
- Department of Physiology, Faculty of Medicine, Semmelweis University, Hungarian Academy of Sciences, Budapest, Hungary
| | - Péter Várnai
- Department of Physiology, Faculty of Medicine, Semmelweis University, Hungarian Academy of Sciences, Budapest, Hungary
| | - András Spät
- Department of Physiology, Faculty of Medicine, Semmelweis University, Hungarian Academy of Sciences, Budapest, Hungary
- Laboratory of Neurobiochemistry and Molecular Physiology, Hungarian Academy of Sciences, Budapest, Hungary
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Hunyady L, Soltész‐Katona E, Erdélyi L, Várnai P, Balla A. Detection of angiotensin II‐induced Ras activation in the trans‐Golgi network and the endoplasmic reticulum using BRET‐based biosensors. FASEB J 2011. [DOI: 10.1096/fasebj.25.1_supplement.lb131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Laszló Hunyady
- Department of PhysiologySemmelweis UniversityBudapestHungary
| | | | - László Erdélyi
- Department of PhysiologySemmelweis UniversityBudapestHungary
| | - Péter Várnai
- Department of PhysiologySemmelweis UniversityBudapestHungary
| | - András Balla
- Department of PhysiologySemmelweis UniversityBudapestHungary
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39
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Szalai B, Barkai L, Várnai P, Hunyady L. Functional interactions within the angiotensin AT1 receptor oligomers ‐ the role of the conserved DRY motif. FASEB J 2011. [DOI: 10.1096/fasebj.25.1_supplement.lb406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Bence Szalai
- Department of PhysiologySemmelweis UniversityBudapestHungary
| | - László Barkai
- Department of PhysiologySemmelweis UniversityBudapestHungary
| | - Péter Várnai
- Department of PhysiologySemmelweis UniversityBudapestHungary
| | - László Hunyady
- Department of PhysiologySemmelweis UniversityBudapestHungary
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Balla A, Erdélyi LS, Soltész-Katona E, Balla T, Várnai P, Hunyady L. Demonstration of angiotensin II-induced Ras activation in the trans-Golgi network and endoplasmic reticulum using bioluminescence resonance energy transfer-based biosensors. J Biol Chem 2010; 286:5319-27. [PMID: 21062747 DOI: 10.1074/jbc.m110.176933] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Previous studies have demonstrated that molecules of the Ras signaling pathway are present in intracellular compartments, including early endosomes, the endoplasmic reticulum (ER), and the Golgi, and suggested that mitogens can regulate Ras activity in these endomembranes. In this study, we investigated the effect of angiotensin II (AngII) on intracellular Ras activity in living HEK293 cells expressing angiotensin type 1 receptors (AT(1)-Rs) using newly developed bioluminescence resonance energy transfer biosensors. To investigate the subcellular localization of AngII-induced Ras activation, we targeted our probes to various intracellular compartments, such as the trans-Golgi network (TGN), the ER, and early endosomes. Using these biosensors, we detected AngII-induced Ras activation in the TGN and ER, but not in early endosomes. In cells expressing a cytoplasmic tail deletion AT(1)-R mutant, the AngII-induced response was enhanced, suggesting that receptor internalization and β-arrestin binding are not required for AngII-induced Ras activation in endomembranes. Although we were able to demonstrate EGF-induced Ras activation in the plasma membrane and TGN, but not in other endomembranes, AG1478, an EGF receptor inhibitor, did not affect the AngII-induced response, suggesting that the latter is independent of EGF receptor transactivation. AngII was unable to stimulate Ras activity in the studied compartments in cells expressing a G protein coupling-deficient AT(1)-R mutant ((125)DRY(127) to (125)AAY(127)). These data suggest that AngII can stimulate Ras activity in the TGN and ER with a G protein-dependent mechanism, which does not require β-arrestin-mediated signaling, receptor internalization, and EGF receptor transactivation.
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Affiliation(s)
- András Balla
- Department of Physiology, Faculty of Medicine, Semmelweis University, H-1444 Budapest, Hungary
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41
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Abstract
Formation of intra- and intermolecular disulfide bonds is an essential step in the synthesis of secretory proteins. In eukaryotic cells, this process occurs in the endoplasmic reticulum (ER) and requires an oxidative environment with the action of several chaperones and folding catalysts. During protein folding, Ero1p oxidizes protein disulfide isomerase (PDI), which then directly catalyzes the formation of disulfide bonds in folding proteins. Recent cell-free studies suggest that the terminal electron acceptor in the pathway is molecular oxygen, with the resulting formation of hydrogen peroxide (H(2)O(2)). We report for the first time the measurement of ER H(2)O(2) level in live cells. By targeting a fluorescent protein-based H(2)O(2) sensor to various intracellular compartments, we show that the ER has the highest level of H(2)O(2), and this high concentration is well confined to the lumen of the organelle. Manipulation of the Ero1-Lalpha level--either by overexpression or by siRNA-mediated inhibition--caused parallel changes in luminal H(2)O(2), proving that the activity of Ero1-Lalpha results in H(2)O(2) formation in the ER. We also found that calcium mobilization from intracellular stores induces a decrease in ER H(2)O(2) level, suggesting a complex interplay between redox and calcium signaling in the mammalian ER.
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Affiliation(s)
- Balázs Enyedi
- Department of Physiology, Semmelweis University, Faculty of Medicine, Budapest, Hungary
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Csordás G, Várnai P, Golenár T, Roy S, Purkins G, Schneider TG, Balla T, Hajnóczky G. Imaging interorganelle contacts and local calcium dynamics at the ER-mitochondrial interface. Mol Cell 2010; 39:121-32. [PMID: 20603080 DOI: 10.1016/j.molcel.2010.06.029] [Citation(s) in RCA: 548] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Revised: 04/09/2010] [Accepted: 06/14/2010] [Indexed: 12/11/2022]
Abstract
The ER-mitochondrial junction provides a local calcium signaling domain that is critical for both matching energy production with demand and the control of apoptosis. Here, we visualize ER-mitochondrial contact sites and monitor the localized [Ca(2+)] changes ([Ca(2+)](ER-mt)) using drug-inducible fluorescent interorganelle linkers. We show that all mitochondria have contacts with the ER, but plasma membrane (PM)-mitochondrial contacts are less frequent because of interleaving ER stacks in both RBL-2H3 and H9c2 cells. Single mitochondria display discrete patches of ER contacts and show heterogeneity in the ER-mitochondrial Ca(2+) transfer. Pericam-tagged linkers revealed IP(3)-induced [Ca(2+)](ER-mt) signals that exceeded 9 microM and endured buffering bulk cytoplasmic [Ca(2+)] increases. Altering linker length to modify the space available for the Ca(2+) transfer machinery had a biphasic effect on [Ca(2+)](ER-mt) signals. These studies provide direct evidence for the existence of high-Ca(2+) microdomains between the ER and mitochondria and suggest an optimal gap width for efficient Ca(2+) transfer.
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Affiliation(s)
- György Csordás
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
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Abstract
The assembly of DNA duplexes into higher-order structures plays a major role in many vital cellular functions such as recombination, chromatin packaging and gene regulation. However, little is currently known about the molecular structure and stability of direct DNA–DNA interactions that are required for such functions. In nature, DNA helices minimize electrostatic repulsion between double helices in several ways. Within crystals, B-DNA forms either right-handed crossovers by groove–backbone interaction or left-handed crossovers by groove–groove juxtaposition. We evaluated the stability of such crossovers at various ionic concentrations using large-scale atomistic molecular dynamics simulations. Our results show that right-handed DNA crossovers are thermodynamically stable in solution in the presence of divalent cations. Attractive forces at short-range stabilize such crossover structures with inter-axial separation of helices less than 20 Å. Right-handed crossovers, however, dissociate swiftly in the presence of monovalent ions only. Surprisingly, left-handed crossovers, assembled by sequence-independent juxtaposition of the helices, appear unstable even at the highest concentration of Mg2+studied here. Our study provides new molecular insights into chiral association of DNA duplexes and highlights the unique role divalent cations play in differential stabilization of crossover structures. These results may serve as a rational basis to understand the role DNA crossovers play in biological processes.
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Affiliation(s)
- Péter Várnai
- Department of Chemistry and Biochemistry, University of Sussex, Brighton, BN1 9QJ, UK.
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44
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Abstract
DNA supercoiling plays a major role in many cellular functions. The global DNA conformation is however intimately linked to local DNA-DNA interactions influencing both the physical properties and the biological functions of the supercoiled molecule. Juxtaposition of DNA double helices in ubiquitous crossover arrangements participates in multiple functions such as recombination, gene regulation and DNA packaging. However, little is currently known about how the structure and stability of direct DNA-DNA interactions influence the topological state of DNA. Here, a crystallographic analysis shows that due to the intrinsic helical chirality of DNA, crossovers of opposite handedness exhibit markedly different geometries. While right-handed crossovers are self-fitted by sequence-specific groove-backbone interaction and bridging Mg(2+) sites, left-handed crossovers are juxtaposed by groove-groove interaction. Our previous calculations have shown that the different geometries result in differential stabilisation in solution, in the presence of divalent cations. The present study reveals that the various topological states of the cell are associated with different inter-segmental interactions. While the unstable left-handed crossovers are exclusively formed in negatively supercoiled DNA, stable right-handed crossovers constitute the local signature of an unusual topological state in the cell, such as the positively supercoiled or relaxed DNA. These findings not only provide a simple mechanism for locally sensing the DNA topology but also lead to the prediction that, due to their different tertiary intra-molecular interactions, supercoiled molecules of opposite signs must display markedly different physical properties. Sticky inter-segmental interactions in positively supercoiled or relaxed DNA are expected to greatly slow down the slithering dynamics of DNA. We therefore suggest that the intrinsic helical chirality of DNA may have oriented the early evolutionary choices for DNA topology.
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Affiliation(s)
- Youri Timsit
- Information Génomique et Structurale, CNRS-UPR2589, Institut de Microbiologie de la Méditerranée, Parc Scientifique de Luminy, Marseille, France.
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Csordás G, Várnai P, Golenár T, Roy S, Purkins G, Balla T, Hajnóczky G. Imaging Interorganelle Contacts and Local Calcium Dynamics at the ER-Mitochondrial Interface. Biophys J 2010. [DOI: 10.1016/j.bpj.2009.12.2053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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46
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Gáspári Z, Várnai P, Szappanos B, Perczel A. Reconciling the lock-and-key and dynamic views of canonical serine protease inhibitor action. FEBS Lett 2009; 584:203-6. [DOI: 10.1016/j.febslet.2009.11.058] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Revised: 11/11/2009] [Accepted: 11/12/2009] [Indexed: 11/28/2022]
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Szalai B, Várnai P, Hunyady L. Transactivation within the AT1 angiotensin receptor homodimer: the role of the conserved DRY motif. BMC Pharmacol 2009. [PMCID: PMC2778924 DOI: 10.1186/1471-2210-9-s2-a51] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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48
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Tóth D, Hunyady L, Várnai P. Investigation of the PtdIns(4,5)P2 dependence of plasma membrane receptor endocytosis in living cells. BMC Pharmacol 2009. [PMCID: PMC2778923 DOI: 10.1186/1471-2210-9-s2-a50] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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49
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Szekeres M, Turu G, Orient A, Szalai B, Süpeki K, Cserzo M, Várnai P, Hunyady L. Mechanisms of angiotensin II-mediated regulation of aldosterone synthase expression in H295R human adrenocortical and rat adrenal glomerulosa cells. Mol Cell Endocrinol 2009; 302:244-53. [PMID: 19418629 DOI: 10.1016/j.mce.2008.12.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
In adrenal zona glomerulosa cells angiotensin II (Ang II) is a key regulator of steroidogenesis. Our purpose was to compare the mechanisms of Ang II-induced changes in the expression level of early transcription factors NR4A1 (NGFIB) and NR4A2 (Nurr1) genes, and the CYP11B2 gene encoding aldosterone synthase in H295R human adrenocortical tumor cells and in primary rat adrenal glomerulosa cells. Real-time PCR studies have demonstrated that Ang II increased the expression levels of NR4A1 and NR4A2 in H295R cells within 1 h after stimulation, which persisted up to 6 h; whereas in rat adrenal glomerulosa cells the kinetics of the expression of these genes were more rapid and transient. Ang II also induced prolonged nuclear translocation of Nurr1 and NGFIB proteins in both cell types. Studies using MEK inhibitor (PD98059, 20 microM), protein kinase C inhibitor (BIM1, 3 microM) and calmodulin kinase (CAMK) inhibitor (KN93, 10 microM) revealed that in rat adrenal glomerulosa cells CAMK-mediated mechanisms play a predominant role in the regulation of CYP11B2. In accordance with earlier findings, in H295R cells MEK inhibition increased the expression of NR4A1, NR4A2 and CYP11B2 genes, however, it decreased the Ang II-induced gene expression levels, suggesting that ERK activation has a role in control of expression of these genes. No such mechanism was detected in rat glomerulosa cells. Sar1-Ile4-Ile8-AngII, which can cause G protein-independent ERK activation, also stimulated the expression of CYP11B2 in H295R cells. These data suggest that the previously reported CAMK-mediated stimulation of early transcription factors NGFIB and Nurr1 has a predominant role in Ang II-induced CYP11B2 activation in rat adrenal glomerulosa cells, whereas in H295R cells ERK activation and G protein-independent mechanisms also contribute to this process.
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Affiliation(s)
- Mária Szekeres
- Department of Physiology, Semmelweis University, Faculty of Medicine, Budapest, Hungary.
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50
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Abstract
This unit describes the method of following phosphoinositide dynamics in live cells. Inositol phospholipids have emerged as universal signaling molecules present in virtually every membrane of eukaryotic cells. Phosphoinositides are present in only tiny amounts as compared to structural lipids, but they are metabolically very active as they are produced and degraded by the numerous inositide kinase and phosphatase enzymes. Phosphoinositides control the membrane recruitment and activity of many membrane protein signaling complexes in specific membrane compartments, and they have been implicated in the regulation of a variety of signaling and trafficking pathways. It has been a challenge to develop methods that allow detection of phosphoinositides at the single-cell level. The only available technique in live cell applications is based on the use of the same protein domains selected by evolution to recognize cellular phosphoinositides. Some of these isolated protein modules, when fused to fluorescent proteins, can follow dynamic changes in phosphoinositides. While this technique can provide information on phosphoinositide dynamics in live cells with subcellular localization, and it has rapidly gained popularity, it also has several limitations that must be taken into account when interpreting the data. This unit summarizes the design and practical use of these constructs and also reviews important considerations for interpretation of the data obtained by this technique.
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Affiliation(s)
- Tamas Balla
- National Institutes of Health, Bethesda, Maryland, USA
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