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Anannya O, Huang W, August A. The kinase ITK controls a Ca 2+-mediated switch that balances T H17 and T reg cell differentiation. Sci Signal 2024; 17:eadh2381. [PMID: 39042726 DOI: 10.1126/scisignal.adh2381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Revised: 11/13/2023] [Accepted: 07/01/2024] [Indexed: 07/25/2024]
Abstract
The balance of proinflammatory T helper type 17 (TH17) and anti-inflammatory T regulatory (Treg) cells is crucial for immune homeostasis in health and disease. The differentiation of naïve CD4+ T cells into TH17 and Treg cells depends on T cell receptor (TCR) signaling mediated, in part, by interleukin-2-inducible T cell kinase (ITK), which stimulates mitogen-activated protein kinases (MAPKs) and Ca2+ signaling. Here, we report that, in the absence of ITK activity, naïve murine CD4+ T cells cultured under TH17-inducing conditions expressed the Treg transcription factor Foxp3 and did not develop into TH17 cells. Furthermore, ITK inhibition in vivo during allergic inflammation increased the Treg:TH17 ratio in the lung. These switched Foxp3+ Treg-like cells had suppressive function, and their transcriptomic profile resembled that of differentiated, induced Treg (iTreg) cells, but their chromatin accessibility profiles were intermediate between TH17 and iTreg cells. Like iTreg cells, switched Foxp3+ Treg-like cells had reductions in the expression of genes involved in mitochondrial oxidative phosphorylation and glycolysis, in the activation of the mechanistic target of rapamycin (mTOR) signaling pathway, and in the abundance of the TH17 pioneer transcription factor BATF. This ITK-dependent switch between TH17 and Treg cells depended on Ca2+ signaling but not on MAPKs. These findings suggest potential strategies for fine-tuning TCR signal strength through ITK to control the balance of TH17 and Treg cells.
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Affiliation(s)
- Orchi Anannya
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Weishan Huang
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
- Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Avery August
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
- Cornell Center for Immunology, Cornell University, Ithaca, NY 14853, USA
- Cornell Institute of Host-Microbe Interactions and Disease, Cornell University, Ithaca, NY 14853, USA
- Cornell Center for Health Equity, Cornell University, Ithaca, NY 14853, USA
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2
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Ren C, Carrillo ND, Cryns VL, Anderson RA, Chen M. Environmental pollutants and phosphoinositide signaling in autoimmunity. JOURNAL OF HAZARDOUS MATERIALS 2024; 465:133080. [PMID: 38091799 PMCID: PMC10923067 DOI: 10.1016/j.jhazmat.2023.133080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 11/16/2023] [Accepted: 11/22/2023] [Indexed: 02/08/2024]
Abstract
Environmental pollution stands as one of the most critical challenges affecting human health, with an estimated mortality rate linked to pollution-induced non-communicable diseases projected to range from 20% to 25%. These pollutants not only disrupt immune responses but can also trigger immunotoxicity. Phosphoinositide signaling, a pivotal regulator of immune responses, plays a central role in the development of autoimmune diseases and exhibits high sensitivity to environmental stressors. Among these stressors, environmental pollutants have become increasingly prevalent in our society, contributing to the initiation and exacerbation of autoimmune conditions. In this review, we summarize the intricate interplay between phosphoinositide signaling and autoimmune diseases within the context of environmental pollutants and contaminants. We provide an up-to-date overview of stress-induced phosphoinositide signaling, discuss 14 selected examples categorized into three groups of environmental pollutants and their connections to immune diseases, and shed light on the associated phosphoinositide signaling pathways. Through these discussions, this review advances our understanding of how phosphoinositide signaling influences the coordinated immune response to environmental stressors at a biological level. Furthermore, it offers valuable insights into potential research directions and therapeutic targets aimed at mitigating the impact of environmental pollutants on the pathogenesis of autoimmune diseases. SYNOPSIS: Phosphoinositide signaling at the intersection of environmental pollutants and autoimmunity provides novel insights for managing autoimmune diseases aggravated by pollutants.
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Affiliation(s)
- Chang Ren
- Department of Pharmacology, Joint Laboratory of Guangdong-Hong Kong Universities for Vascular Homeostasis and Diseases, School of Medicine, Southern University of Science and Technology, Shenzhen 518055, China
| | - Noah D Carrillo
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Vincent L Cryns
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, USA; University of Wisconsin Carbone Cancer Center, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Richard A Anderson
- University of Wisconsin Carbone Cancer Center, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Mo Chen
- Department of Pharmacology, Joint Laboratory of Guangdong-Hong Kong Universities for Vascular Homeostasis and Diseases, School of Medicine, Southern University of Science and Technology, Shenzhen 518055, China.
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3
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Anannya O, Huang W, August A. ITK signaling regulates a switch between T helper 17 and T regulatory cell lineages via a calcium-mediated pathway. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.01.535229. [PMID: 37066370 PMCID: PMC10103963 DOI: 10.1101/2023.04.01.535229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
The balance of pro-inflammatory T helper type 17 (Th17) and anti-inflammatory T regulatory (Treg) cells is crucial in maintaining immune homeostasis in health and disease conditions. Differentiation of naïve CD4+ T cells into Th17/Treg cells is dependent upon T cell receptor (TCR) activation and cytokine signaling, which includes the kinase ITK. Signals from ITK can regulate the differentiation of Th17 and Treg cell fate choice, however, the mechanism remains to be fully understood. We report here that in the absence of ITK activity, instead of developing into Th17 cells under Th17 conditions, naïve CD4+ T cells switch to cells expressing the Treg marker Foxp3 (Forkhead box P3). These switched Foxp3+ Treg like cells retain suppressive function and resemble differentiated induced Tregs in their transcriptomic profile, although their chromatin accessibility profiles are intermediate between Th17 and induced Tregs cells. Generation of the switched Foxp3+ Treg like cells was associated with reduced expression of molecules involved in mitochondrial oxidative phosphorylation and glycolysis, with reduced activation of the mTOR signaling pathway, and reduced expression of BATF. This ITK dependent switch between Th17 and Treg cells was reversed by increasing intracellular calcium. These findings suggest potential strategies for fine tune the TCR signal strength via ITK to regulate the balance of Th17/Treg cells.
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Affiliation(s)
- Orchi Anannya
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA
| | - Weishan Huang
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA
- Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Avery August
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA
- Cornell Center for Immunology, Cornell University, Ithaca, NY 14853, USA
- Cornell Institute of Host-Microbe Interactions and Defense, Cornell University, Ithaca, NY 14853, USA
- Cornell Center for Health Equity, Cornell University, Ithaca, NY 14853, USA
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4
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Weako J, Jang H, Keskin O, Nussinov R, Gursoy A. The structural basis of Akt PH domain interaction with calmodulin. Biophys J 2021; 120:1994-2008. [PMID: 33775637 PMCID: PMC8204387 DOI: 10.1016/j.bpj.2021.03.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 03/10/2021] [Accepted: 03/18/2021] [Indexed: 11/17/2022] Open
Abstract
Akt plays a key role in the Ras/PI3K/Akt/mTOR signaling pathway. In breast cancer, Akt translocation to the plasma membrane is enabled by the interaction of its pleckstrin homology domain (PHD) with calmodulin (CaM). At the membrane, the conformational change promoted by PIP3 releases CaM and facilitates Thr308 and Ser473 phosphorylation and activation. Here, using modeling and molecular dynamics simulations, we aim to figure out how CaM interacts with Akt's PHD at the atomic level. Our simulations show that CaM-PHD interaction is thermodynamically stable and involves a β-strand rather than an α-helix, in agreement with NMR data, and that electrostatic and hydrophobic interactions are critical. The PHD interacts with CaM lobes; however, multiple modes are possible. IP4, the polar head of PIP3, weakens the CaM-PHD interaction, implicating the release mechanism at the plasma membrane. Recently, we unraveled the mechanism of PI3Kα activation at the atomistic level and the structural basis for Ras role in the activation. Here, our atomistic structural data clarify the mechanism of how CaM interacts, delivers, and releases Akt-the next node in the Ras/PI3K pathway-at the plasma membrane.
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Affiliation(s)
- Jackson Weako
- Computational Science and Engineering Program, Koç University, Istanbul, Turkey
| | - Hyunbum Jang
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research in the Laboratory of Cancer Immunometabolism, National Cancer Institute, Frederick, Maryland
| | - Ozlem Keskin
- Department of Chemical and Biological Engineering, Koç University, Istanbul, Turkey
| | - Ruth Nussinov
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research in the Laboratory of Cancer Immunometabolism, National Cancer Institute, Frederick, Maryland; Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
| | - Attila Gursoy
- Department of Computer Engineering, Koç University, Istanbul, Turkey.
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5
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Tuning T helper cell differentiation by ITK. Biochem Soc Trans 2020; 48:179-185. [PMID: 32049330 DOI: 10.1042/bst20190486] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 12/28/2019] [Accepted: 01/13/2020] [Indexed: 12/24/2022]
Abstract
CD4+ effector T cells effectuate T cell immune responses, producing cytokines to orchestrate the nature and type of immune responses. The non-receptor tyrosine kinase IL-2 inducible T cell kinase (ITK), a mediator of T cell Receptor signaling, plays a critical role in tuning the development of these effector cells. In this review we discussed the role that signals downstream of ITK, including the Ras/MAPK pathway, play in differentially controlling the differentiation of TH17, Foxp3+ T regulatory (Treg) cells, and Type 1 regulatory T (Tr1) cells, supporting a model of ITK signals controlling a decision point in the effector T cell differentiation process.
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Liu L, Li H, Labbe B, Wang Y, Mao S, Cao Y, Zhao M, Liu S, Yu H, Deng X. Involvement of CaMKII in regulating the release of diplotene-arrested mouse oocytes by pAkt1 (Ser473). Cell Cycle 2019; 18:2986-2997. [PMID: 31530151 PMCID: PMC6791694 DOI: 10.1080/15384101.2019.1666596] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 09/04/2019] [Accepted: 09/06/2019] [Indexed: 10/26/2022] Open
Abstract
Calcium (Ca2+)/calmodulin-dependent protein kinase II (CaMKII) had been reported to play a role in the process of fertilization. However, the role of CaMKII in the release of diplotene-arrested oocytes is poorly understood. In this study, we explored the potential effect of CaMKII on Akt1 and the relationship among CaMKII, Akt1 and phosphatidylinositol (3,4,5)-trisphosphate (PIP3) during the meiotic resumption of mouse oocytes. We found that inhibition of CaMKII aggravated diplotene arrest. We detected the expression and distribution of pCaMKII (Thr286), pAkt1 (Ser473), Cdc25B and pCdc2 (Tyr15) when oocytes were treated with KN-93, SH-6, LY294002 or PIP3, respectively. Our data showed that down-regulated CaMKII by KN-93 decreased the levels of pAkt1 (Ser473) and rearranged the distribution of pAkt1 (Ser473). Meanwhile, down-regulated pAkt1 (Ser473) by SH-6 also decreased the levels of pCaMKII (Thr286), Cdc25B and pCdc2 (Tyr15) significantly and rearranged the distributions of pCaMKII (Thr286). Furthermore, our data showed that exogenous PIP3 up-regulated GVBD rates significantly and increased the levels of pCaMKII (Thr286) and pAkt1 (Ser473). On the contrary, down-regulation of PIP3 by LY294002 decreased GVBD rates and the levels of pCaMKII (Thr286) and pAkt1 (Ser473), respectively. Our results showed that Akt1 and CaMKII regulated each other, and PIP3 may be involved in these regulations during the release of mouse oocytes from diplotene arrest.
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Affiliation(s)
- Lingling Liu
- Central Laboratory of the Fourth Affiliated Hospital, CMU, Shenyang, PR China
- Department of Physiology, China Medical University (CMU), Shenyang, PR China
- Mouse Genome Editing Core, Dept of Laboratory Animal Science, Shanghai Public Health Clincial Center, Fudan University, Shanghai, PR China
| | - Hanwen Li
- Department of Anorectum, the Fourth Affiliated Hospital, China Medical University (CMU), Shenyang, PR China
| | - Ben Labbe
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Yang Wang
- Department of Physiology, China Medical University (CMU), Shenyang, PR China
| | - Shitao Mao
- Department of Pneumology, the Fourth Affiliated Hospital, CMU, Shenyang, PR China
| | - Yu Cao
- Department of Physiology, China Medical University (CMU), Shenyang, PR China
| | - Mingjing Zhao
- Department of Pneumology, the Fourth Affiliated Hospital, CMU, Shenyang, PR China
| | - Shuo Liu
- Department of Pneumology, the Fourth Affiliated Hospital, CMU, Shenyang, PR China
| | - Hang Yu
- Department of Biophysics, China Medical University (CMU), Shenyang, China
| | - Xin Deng
- Central Laboratory of the Fourth Affiliated Hospital, CMU, Shenyang, PR China
- Department of Physiology, China Medical University (CMU), Shenyang, PR China
- Department of Pneumology, the Fourth Affiliated Hospital, CMU, Shenyang, PR China
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Andreotti AH, Joseph RE, Conley JM, Iwasa J, Berg LJ. Multidomain Control Over TEC Kinase Activation State Tunes the T Cell Response. Annu Rev Immunol 2019; 36:549-578. [PMID: 29677469 DOI: 10.1146/annurev-immunol-042617-053344] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Signaling through the T cell antigen receptor (TCR) activates a series of tyrosine kinases. Directly associated with the TCR, the SRC family kinase LCK and the SYK family kinase ZAP-70 are essential for all downstream responses to TCR stimulation. In contrast, the TEC family kinase ITK is not an obligate component of the TCR cascade. Instead, ITK functions as a tuning dial, to translate variations in TCR signal strength into differential programs of gene expression. Recent insights into TEC kinase structure have provided a view into the molecular mechanisms that generate different states of kinase activation. In resting lymphocytes, TEC kinases are autoinhibited, and multiple interactions between the regulatory and kinase domains maintain low activity. Following TCR stimulation, newly generated signaling modules compete with the autoinhibited core and shift the conformational ensemble to the fully active kinase. This multidomain control over kinase activation state provides a structural mechanism to account for ITK's ability to tune the TCR signal.
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Affiliation(s)
- Amy H Andreotti
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa 50011, USA; ,
| | - Raji E Joseph
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa 50011, USA; ,
| | - James M Conley
- Department of Pathology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA; ,
| | - Janet Iwasa
- Department of Biochemistry, University of Utah, Salt Lake City, Utah 84112, USA;
| | - Leslie J Berg
- Department of Pathology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA; ,
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A negative role for the interleukin-2-inducible T-cell kinase (ITK) in human Foxp3+ TREG differentiation. PLoS One 2019; 14:e0215963. [PMID: 31022269 PMCID: PMC6483201 DOI: 10.1371/journal.pone.0215963] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 04/11/2019] [Indexed: 01/13/2023] Open
Abstract
The Tec kinases ITK (interleukin-2-inducible T-cell kinase) and RLK (resting lymphocyte kinase) are critical components of the proximal TCR/CD3 signal transduction machinery, and data in mice suggest that ITK negatively modulates regulatory T cell (TREG) differentiation. However, whether Tec kinases modulate TREG development and/or function in human T cells remains unknown. Using a novel self-delivery siRNA platform (sdRNA), we found that ITK knockdown in human primary naïve peripheral blood CD4 T cells increased Foxp3+ expression under both TREG and T helper priming conditions. TREG differentiated under ITK knockdown conditions exhibited enhanced expression of the co-inhibitory receptor PD-1 and were suppressive in a T cell proliferation assay. ITK knockdown decreased IL-17A production in T cells primed under Th17 conditions and promoted Th1 differentiation. Lastly, a dual ITK/RLK Tec kinase inhibitor did not induce Foxp3 in CD4 T cells, but conversely abrogated Foxp3 expression induced by ITK knockdown. Our data suggest that targeting ITK in human T cells may be an effective approach to boost TREG in the context of autoimmune diseases, but concomitant inhibition of other Tec family kinases may negate this effect.
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Agamasu C, Ghirlando R, Taylor T, Messing S, Tran TH, Bindu L, Tonelli M, Nissley DV, McCormick F, Stephen AG. KRAS Prenylation Is Required for Bivalent Binding with Calmodulin in a Nucleotide-Independent Manner. Biophys J 2019; 116:1049-1063. [PMID: 30846362 PMCID: PMC6428923 DOI: 10.1016/j.bpj.2019.02.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 01/30/2019] [Accepted: 02/04/2019] [Indexed: 12/11/2022] Open
Abstract
Deregulation of KRAS4b signaling pathway has been implicated in 30% of all cancers. Membrane localization of KRAS4b is an essential step for the initiation of the downstream signaling cascades that guide various cellular mechanisms. KRAS4b plasma membrane (PM) binding is mediated by the insertion of a prenylated moiety that is attached to the terminal carboxy-methylated cysteine, in addition to electrostatic interactions of its positively charged hypervariable region with anionic lipids. Calmodulin (CaM) has been suggested to selectively bind KRAS4b to act as a negative regulator of the RAS/mitogen-activated protein kinase (MAPK) signaling pathway by displacing KRAS4b from the membrane. However, the mechanism by which CaM can recognize and displace KRAS4b from the membrane is not well understood. In this study, we employed biophysical and structural techniques to characterize this mechanism in detail. We show that KRAS4b prenylation is required for binding to CaM and that the hydrophobic pockets of CaM can accommodate the prenylated region of KRAS4b, which might represent a novel CaM-binding motif. Remarkably, prenylated KRAS4b forms a 2:1 stoichiometric complex with CaM in a nucleotide-independent manner. The interaction between prenylated KRAS4b and CaM is enthalpically driven, and electrostatic interactions also contribute to the formation of the complex. The prenylated KRAS4b terminal KSKTKC-farnesylation and carboxy-methylation is sufficient for binding and defines the minimal CaM-binding motif. This is the same region implicated in membrane and phosphodiesterase6-δ binding. Finally, we provide a structure-based docking model by which CaM binds to prenylated KRAS4b. Our data provide new insights into the KRAS4b-CaM interaction and suggest a possible mechanism whereby CaM can regulate KRAS4b membrane localization.
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Affiliation(s)
- Constance Agamasu
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, Maryland
| | - Rodolfo Ghirlando
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Troy Taylor
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, Maryland
| | - Simon Messing
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, Maryland
| | - Timothy H Tran
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, Maryland
| | - Lakshman Bindu
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, Maryland
| | - Marco Tonelli
- National Magnetic Resource Facility at Madison, Biochemistry Department, University of Wisconsin-Madison, Madison, Wisconsin
| | - Dwight V Nissley
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, Maryland
| | - Frank McCormick
- Diller Family Comprehensive Cancer Center, University of California, San Francisco, California
| | - Andrew G Stephen
- NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc., Frederick, Maryland.
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Yuan J, Ng WH, Tian Z, Yap J, Baccarini M, Chen Z, Hu J. Activating mutations in MEK1 enhance homodimerization and promote tumorigenesis. Sci Signal 2018; 11:eaar6795. [PMID: 30377225 DOI: 10.1126/scisignal.aar6795] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
RAS-RAF-MEK-ERK signaling has a well-defined role in cancer biology. Although aberrant pathway activation occurs mostly upstream of the kinase MEK, mutations in MEK are prevalent in some cancer subsets. Here, we found that cancer-related, activating mutations in MEK can be classified into two groups: those that relieve inhibitory interactions with the helix A region and those that are in-frame deletions of the β3-αC loop, which enhance MEK1 homodimerization. The former, helix A-associated mutants, are inhibited by traditional MEK inhibitors. However, we found that the increased homodimerization associated with the loop-deletion mutants promoted intradimer cross-phosphorylation of the activation loop and conferred differential resistance to MEK inhibitors both in vitro and in vivo. MEK1 dimerization was required both for its activation by the kinase RAF and for its catalytic activity toward the kinase ERK. Our findings not only identify a previously unknown group of MEK mutants and provide insight into some key steps in RAF-MEK-ERK activation but also have implications for the design of therapies targeting RAS-ERK signaling in cancers.
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Affiliation(s)
- Jimin Yuan
- Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Drive, 169610 Singapore, Singapore
| | - Wan Hwa Ng
- Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Drive, 169610 Singapore, Singapore
| | - Zizi Tian
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Jiajun Yap
- Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Drive, 169610 Singapore, Singapore
| | - Manuela Baccarini
- Max F. Perutz Laboratories, University of Vienna, Doktor-Bohr-Gasse 9, 1030 Vienna, Austria
| | - Zhongzhou Chen
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Jiancheng Hu
- Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Drive, 169610 Singapore, Singapore.
- Cancer and Stem Cell Program, Duke-NUS Medical School, 8 College Road, 169857 Singapore, Singapore
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11
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Stimulus strength determines the BTK-dependence of the SHIP1-deficient phenotype in IgE/antigen-triggered mast cells. Sci Rep 2018; 8:15467. [PMID: 30341350 PMCID: PMC6195619 DOI: 10.1038/s41598-018-33769-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 10/05/2018] [Indexed: 01/27/2023] Open
Abstract
Antigen (Ag)-mediated crosslinking of IgE-loaded high-affinity receptors for IgE (FcεRI) on mast cells (MCs) triggers activation of proinflammatory effector functions relevant for IgE-associated allergic disorders. The cytosolic tyrosine kinase BTK and the SH2-containing inositol-5'-phosphatase SHIP1 are central positive and negative regulators of Ag-triggered MC activation, respectively, contrarily controlling Ca2+ mobilisation, degranulation, and cytokine production. Using genetic and pharmacological techniques, we examined whether BTK activation in Ship1-/- MCs is mandatory for the manifestation of the well-known hyperactive phenotype of Ship1-/- MCs. We demonstrate the prominence of BTK for the Ship1-/- phenotype in a manner strictly dependent on the strength of the initial Ag stimulus; particular importance for BTK was identified in Ship1-/- bone marrow-derived MCs in response to stimulation with suboptimal Ag concentrations. With respect to MAPK activation, BTK showed particular importance at suboptimal Ag concentrations, allowing for an analogous-to-digital switch resulting in full activation of ERK1/2 already at low Ag concentrations. Our data allow for a more precise definition of the role of BTK in FcεRI-mediated signal transduction and effector function in MCs. Moreover, they suggest that reduced activation or curtate expression of SHIP1 can be compensated by pharmacological inhibition of BTK and vice versa.
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12
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Yuan J, Ng WH, Lam PYP, Wang Y, Xia H, Yap J, Guan SP, Lee ASG, Wang M, Baccarini M, Hu J. The dimer-dependent catalytic activity of RAF family kinases is revealed through characterizing their oncogenic mutants. Oncogene 2018; 37:5719-5734. [PMID: 29930381 PMCID: PMC6202329 DOI: 10.1038/s41388-018-0365-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 05/18/2018] [Accepted: 05/21/2018] [Indexed: 12/19/2022]
Abstract
Although extensively studied for three decades, the molecular mechanisms that regulate the RAF/MEK/ERK kinase cascade remain ambiguous. Recent studies identified the dimerization of RAF as a key event in the activation of this cascade. Here, we show that in-frame deletions in the β3-αC loop activate ARAF as well as BRAF and other oncogenic kinases by enforcing homodimerization. By characterizing these RAF mutants, we find that ARAF has less allosteric and catalytic activity than the other two RAF isoforms, which arises from its non-canonical APE motif. Further, these RAF mutants exhibit a strong oncogenic potential, and a differential inhibitor resistance that correlates with their dimer affinity. Using these unique mutants, we demonstrate that active RAFs, including the BRAF(V600E) mutant, phosphorylate MEK in a dimer-dependent manner. This study characterizes a special category of oncogenic kinase mutations, and elucidates the molecular basis that underlies the differential ability of RAF isoforms to stimulate MEK-ERK pathway. Further, this study reveals a unique catalytic feature of RAF family kinases that can be exploited to control their activities for cancer therapies.
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Affiliation(s)
- Jimin Yuan
- Division of Cellular and Molecular Research, Singapore, Singapore
| | - Wan Hwa Ng
- Division of Cellular and Molecular Research, Singapore, Singapore
| | - Paula Y P Lam
- Division of Cellular and Molecular Research, Singapore, Singapore
- Cancer and Stem Cell Program, Duke-NUS Medical School, 8 College Road, 169857, Singapore, Singapore
| | - Yu Wang
- Division of Cellular and Molecular Research, Singapore, Singapore
| | - Hongping Xia
- Division of Cellular and Molecular Research, Singapore, Singapore
| | - Jiajun Yap
- Division of Cellular and Molecular Research, Singapore, Singapore
| | - Shou Ping Guan
- Division of Cellular and Molecular Research, Singapore, Singapore
| | - Ann S G Lee
- Division of Medical Sciences, National Cancer Centre Singapore, 11 Hospital Drive, Singapore, 169610, Singapore
- Office of Clinical & Academic Faculty Affairs, Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore
- Department of Physiology, National University of Singapore, 2 Medical Drive, 117597, Singapore, Singapore
| | - Mei Wang
- Cancer and Stem Cell Program, Duke-NUS Medical School, 8 College Road, 169857, Singapore, Singapore
| | - Manuela Baccarini
- Max F. Perutz Laboratories, University of Vienna, Doktor-Bohr-Gasse 9, 1030, Vienna, Austria
| | - Jiancheng Hu
- Division of Cellular and Molecular Research, Singapore, Singapore.
- Cancer and Stem Cell Program, Duke-NUS Medical School, 8 College Road, 169857, Singapore, Singapore.
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13
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Yuan J, Ng WH, Yap J, Chia B, Huang X, Wang M, Hu J. The AMPK inhibitor overcomes the paradoxical effect of RAF inhibitors through blocking phospho-Ser-621 in the C terminus of CRAF. J Biol Chem 2018; 293:14276-14284. [PMID: 30030377 PMCID: PMC6139560 DOI: 10.1074/jbc.ra118.004597] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 07/17/2018] [Indexed: 11/15/2022] Open
Abstract
The dimerization-driven paradoxical activation of RAF proto-oncogene Ser/Thr kinase (RAF) is the predominant cause of drug resistance and toxicity in cancer therapies with RAF inhibitors. The scaffold protein 14-3-3, which binds to the RAF C terminus, is essential for RAF activation under physiological conditions, but the molecular basis is unclear. Here we investigated whether and how 14-3-3 regulates the dimerization-driven transactivation of the RAF isoform CRAF by RAF inhibitors and affects drug resistance and toxicity by virtue of the dominant role of CRAF in these processes. We demonstrated that 14-3-3 enhances the dimerization-driven transactivation of CRAF by stabilizing CRAF dimers. Further, we identified AMP-activated protein kinase (AMPK) and CRAF itself as two putative kinases that redundantly phosphorylate CRAF's C terminus and thereby control its association with 14-3-3. Next, we determined whether the combinatory inhibition of AMPK and CRAF could overcome the paradoxical effect of RAF inhibitors. We found that the AMPK inhibitor (AMPKi) not only blocked the RAF inhibitor–driven paradoxical activation of ERK signaling and cellular overgrowth in Ras-mutated cancer cells by blocking phosphorylation of Ser-621 in CRAF but also reduced the formation of drug-resistant clones of BRAFV600E-mutated cancer cells. Last, we investigated whether 14-3-3 binding to the C terminus of CRAF is required for CRAF catalytic activity and observed that it was dispensable in vivo. Altogether, our study unravels the molecular mechanism by which 14-3-3 regulates dimerization-driven RAF activation and identified AMPKi as a potential agent to counteract drug resistance and adverse effects of RAF inhibitors in cancer therapies.
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Affiliation(s)
- Jimin Yuan
- From the Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610, Singapore and
| | - Wan Hwa Ng
- From the Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610, Singapore and
| | - Jiajun Yap
- From the Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610, Singapore and
| | - Brandon Chia
- From the Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610, Singapore and
| | - Xuchao Huang
- From the Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610, Singapore and
| | - Mei Wang
- the Cancer and Stem Cell Program, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
| | - Jiancheng Hu
- From the Division of Cellular and Molecular Research, National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610, Singapore and .,the Cancer and Stem Cell Program, Duke-NUS Medical School, 8 College Road, Singapore 169857, Singapore
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14
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Devkota S, Joseph RE, Boyken SE, Fulton DB, Andreotti AH. An Autoinhibitory Role for the Pleckstrin Homology Domain of Interleukin-2-Inducible Tyrosine Kinase and Its Interplay with Canonical Phospholipid Recognition. Biochemistry 2017; 56:2938-2949. [PMID: 28516764 DOI: 10.1021/acs.biochem.6b01182] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Pleckstrin homology (PH) domains are well-known as phospholipid binding modules, yet evidence that PH domain function extends beyond lipid recognition is mounting. In this work, we characterize a protein binding function for the PH domain of interleukin-2-inducible tyrosine kinase (ITK), an immune cell specific signaling protein that belongs to the TEC family of nonreceptor tyrosine kinases. Its N-terminal PH domain is a well-characterized lipid binding module that localizes ITK to the membrane via phosphatidylinositol 3,4,5-trisphosphate (PIP3) binding. Using a combination of nuclear magnetic resonance spectroscopy and mutagenesis, we have mapped an autoregulatory protein interaction site on the ITK PH domain that makes direct contact with the catalytic kinase domain of ITK, inhibiting the phospho-transfer reaction. Moreover, we have elucidated an important interplay between lipid binding by the ITK PH domain and the stability of the autoinhibitory complex formed by full length ITK. The ITK activation loop in the kinase domain becomes accessible to phosphorylation to the exogenous kinase LCK upon binding of the ITK PH domain to PIP3. By clarifying the allosteric role of the ITK PH domain in controlling ITK function, we have expanded the functional repertoire of the PH domain generally and opened the door to alternative strategies to target this specific kinase in the context of immune cell signaling.
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Affiliation(s)
- Sujan Devkota
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University , Ames, Iowa 50011, United States
| | - Raji E Joseph
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University , Ames, Iowa 50011, United States
| | - Scott E Boyken
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University , Ames, Iowa 50011, United States
| | - D Bruce Fulton
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University , Ames, Iowa 50011, United States
| | - Amy H Andreotti
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University , Ames, Iowa 50011, United States
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15
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Agamasu C, Ghanam RH, Xu F, Sun Y, Chen Y, Saad JS. The Interplay between Calmodulin and Membrane Interactions with the Pleckstrin Homology Domain of Akt. J Biol Chem 2016; 292:251-263. [PMID: 27872186 DOI: 10.1074/jbc.m116.752816] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 11/19/2016] [Indexed: 11/06/2022] Open
Abstract
The Akt protein, a serine/threonine kinase, plays important roles in cell survival, apoptosis, and oncogenes. Akt is translocated to the plasma membrane for activation. Akt-membrane binding is mediated by direct interactions between its pleckstrin homology domain (PHD) and phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P3). It has been shown that Akt activation in breast cancer cells is modulated by calmodulin (CaM). However, the molecular mechanism of the interplay between CaM and membrane binding is not established. Here, we employed nuclear magnetic resonance (NMR) and biochemical and biophysical techniques to characterize how PI(3,4,5)P3, CaM, and membrane mimetics (nanodisc) bind to Akt(PHD). We show that PI(3,4,5)P3 binding to Akt(PHD) displaces the C-terminal lobe of CaM but not the weakly binding N-terminal lobe. However, binding of a PI(3,4,5)P3-embedded membrane nanodisc to Akt(PHD) with a 103-fold tighter affinity than PI(3,4,5)P3 is able to completely displace CaM. We also show that Akt(PHD) binds to both layers of the nanodisc, indicating proper incorporation of PI(3,4,5)P3 on the nanodisc surface. No detectable binding has been observed between Akt(PHD) and PI(3,4,5)P3-free nanodiscs, demonstrating that PI(3,4,5)P3 is required for membrane binding, CaM displacement, and Akt activation. Using pancreatic cancer cells, we demonstrate that inhibition of Akt-CaM binding attenuated Akt activation. Our findings support a model by which CaM binds to Akt to facilitate its translocation to the membrane. Elucidation of the molecular details of the interplay between membrane and CaM binding to Akt may help in the development of potential targets to control the pathophysiological processes of cell survival.
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Affiliation(s)
| | | | - Fei Xu
- Pathology, University of Alabama at Birmingham and
| | - Yong Sun
- Pathology, University of Alabama at Birmingham and.,the Research Department, Birmingham Veterans Affairs Medical Center, Birmingham, Alabama 35294
| | - Yabing Chen
- Pathology, University of Alabama at Birmingham and.,the Research Department, Birmingham Veterans Affairs Medical Center, Birmingham, Alabama 35294
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16
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Bu F, Tian H, Gong S, Zhu Q, Xu GY, Tao J, Jiang X. Phosphorylation of NR2B NMDA subunits by protein kinase C in arcuate nucleus contributes to inflammatory pain in rats. Sci Rep 2015; 5:15945. [PMID: 26515544 PMCID: PMC4626761 DOI: 10.1038/srep15945] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 09/29/2015] [Indexed: 12/18/2022] Open
Abstract
The arcuate nucleus (ARC) of the hypothalamus plays a key role in pain processing. Although it is well known that inhibition of NMDA receptor (NMDAR) in ARC attenuates hyperalgesia induced by peripheral inflammation, the underlying mechanism of NMDAR activation in ARC remains unclear. Protein kinase C (PKC) is involved in several signalling cascades activated in physiological and pathological conditions. Therefore, we hypothesised that upregulation of PKC activates NMDARs in the ARC, thus contributing to inflammatory hyperalgesia. Intra-ARC injection of chelerythrine (CC), a specific PKC inhibitor, attenuated complete Freund’s adjuvant (CFA) induced thermal and mechanical hyperalgesia in a dose-dependent manner. In vivo extracellular recordings showed that microelectrophoresis of CC or MK-801 (a NMDAR antagonist) significantly reduced the enhancement of spontaneous discharges and pain-evoked discharges of ARC neurons. In addition, CFA injection greatly enhanced the expression of total and phosphorylated PKCγ in the ARC. Interestingly, CFA injection also remarkably elevated the level of phosphorylated NR2B (Tyr1472) without affecting the expression of total NR2B. Importantly, intra-ARC injection of CC reversed the upregulation of phosphorylated NR2B subunits in the ARC. Taken together, peripheral inflammation leads to an activation of NMDARs mediated by PKC activation in the ARC, thus producing thermal and mechanical hyperalgesia.
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Affiliation(s)
- Fan Bu
- Key Laboratory of Pain Basic Research and Clinical Therapy, Department of Physiology &Neurobiology, Medical College of Soochow University, Suzhou 215123, P.R. China
| | - Huiyu Tian
- Key Laboratory of Pain Basic Research and Clinical Therapy, Department of Physiology &Neurobiology, Medical College of Soochow University, Suzhou 215123, P.R. China
| | - Shan Gong
- Key Laboratory of Pain Basic Research and Clinical Therapy, Department of Physiology &Neurobiology, Medical College of Soochow University, Suzhou 215123, P.R. China
| | - Qi Zhu
- Key Laboratory of Pain Basic Research and Clinical Therapy, Department of Physiology &Neurobiology, Medical College of Soochow University, Suzhou 215123, P.R. China
| | - Guang-Yin Xu
- Key Laboratory of Pain Basic Research and Clinical Therapy, Department of Physiology &Neurobiology, Medical College of Soochow University, Suzhou 215123, P.R. China.,Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Institute of Neuroscience, Soochow University, Suzhou 215123, P.R. China
| | - Jin Tao
- Key Laboratory of Pain Basic Research and Clinical Therapy, Department of Physiology &Neurobiology, Medical College of Soochow University, Suzhou 215123, P.R. China.,Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Institute of Neuroscience, Soochow University, Suzhou 215123, P.R. China
| | - Xinghong Jiang
- Key Laboratory of Pain Basic Research and Clinical Therapy, Department of Physiology &Neurobiology, Medical College of Soochow University, Suzhou 215123, P.R. China.,Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases, Institute of Neuroscience, Soochow University, Suzhou 215123, P.R. China
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17
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Côte M, Fos C, Canonigo-Balancio AJ, Ley K, Bécart S, Altman A. SLAT promotes TCR-mediated, Rap1-dependent LFA-1 activation and adhesion through interaction of its PH domain with Rap1. J Cell Sci 2015; 128:4341-52. [PMID: 26483383 DOI: 10.1242/jcs.172742] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 10/09/2015] [Indexed: 01/13/2023] Open
Abstract
SLAT (also known as DEF6) promotes T cell activation and differentiation by regulating NFAT-Ca(2+) signaling. However, its role in TCR-mediated inside-out signaling, which induces integrin activation and T cell adhesion, a central process in T cell immunity and inflammation, has not been explored. Here, we show that SLAT is crucial for TCR-induced adhesion to ICAM-1 and affinity maturation of LFA-1 in CD4(+) T cells. Mechanistic studies revealed that SLAT interacts, through its PH domain, with a key component of inside-out signaling, namely the active form of the small GTPase Rap1 (which has two isoforms, Rap1A and Rap1B). This interaction has been further shown to facilitate the interdependent recruitment of Rap1 and SLAT to the T cell immunological synapse upon TCR engagement. Furthermore, a SLAT mutant lacking its PH domain drastically inhibited LFA-1 activation and CD4(+) T cell adhesion. Finally, we established that a constitutively active form of Rap1, which is present at the plasma membrane, rescues the defective LFA-1 activation and ICAM-1 adhesion in SLAT-deficient (Def6(-/-)) T cells. These findings ascribe a new function to SLAT, and identify Rap1 as a target of SLAT function in TCR-mediated inside-out signaling.
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Affiliation(s)
- Marjorie Côte
- Division of Cell Biology, La Jolla Institute for Allergy & Immunology, La Jolla, CA 92037, USA
| | - Camille Fos
- Division of Cell Biology, La Jolla Institute for Allergy & Immunology, La Jolla, CA 92037, USA
| | - Ann J Canonigo-Balancio
- Division of Cell Biology, La Jolla Institute for Allergy & Immunology, La Jolla, CA 92037, USA
| | - Klaus Ley
- Division of Inflammation Biology, La Jolla Institute for Allergy & Immunology, La Jolla, CA 92037, USA
| | - Stéphane Bécart
- Division of Cell Biology, La Jolla Institute for Allergy & Immunology, La Jolla, CA 92037, USA
| | - Amnon Altman
- Division of Cell Biology, La Jolla Institute for Allergy & Immunology, La Jolla, CA 92037, USA
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18
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Agamasu C, Ghanam RH, Saad JS. Structural and Biophysical Characterization of the Interactions between Calmodulin and the Pleckstrin Homology Domain of Akt. J Biol Chem 2015; 290:27403-27413. [PMID: 26391397 DOI: 10.1074/jbc.m115.673939] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Indexed: 11/06/2022] Open
Abstract
The translocation of Akt, a serine/threonine kinase, to the plasma membrane is a critical step in the Akt activation pathway. It is established that membrane binding of Akt is mediated by direct interactions between its pleckstrin homology domain (PHD) and phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P3). There is now evidence that Akt activation in many breast cancer cells is also modulated by the calcium-binding protein, calmodulin (CaM). Upon EGF stimulation of breast cancer cells, CaM co-localizes with Akt at the plasma membrane to enhance activation. However, the molecular details of Akt(PHD) interaction with CaM are not known. In this study, we employed NMR, biochemical, and biophysical techniques to characterize CaM binding to Akt(PHD). Our data show that CaM forms a tight complex with the PHD of Akt (dissociation constant = 100 nm). The interaction between CaM and Akt(PHD) is enthalpically driven, and the affinity is greatly dependent on salt concentration, indicating that electrostatic interactions are important for binding. The CaM-binding interface in Akt(PHD) was mapped to two loops adjacent to the PI(3,4,5)P3 binding site, which represents a rare CaM-binding motif and suggests a synergistic relationship between CaM and PI(3,4,5)P3 upon Akt activation. Elucidation of the mechanism by which Akt interacts with CaM will help in understanding the activation mechanism, which may provide insights for new potential targets to control the pathophysiological processes of cell survival.
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Affiliation(s)
- Constance Agamasu
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Ruba H Ghanam
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Jamil S Saad
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama 35294.
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19
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Wang X, Hills LB, Huang YH. Lipid and Protein Co-Regulation of PI3K Effectors Akt and Itk in Lymphocytes. Front Immunol 2015; 6:117. [PMID: 25821452 PMCID: PMC4358224 DOI: 10.3389/fimmu.2015.00117] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 03/02/2015] [Indexed: 12/21/2022] Open
Abstract
The phosphoinositide 3-kinase (PI 3-kinase, PI3K) pathway transduces signals critical for lymphocyte function. PI3K generates the phospholipid PIP3 at the plasma membrane to recruit proteins that contain pleckstrin homology (PH) domains – a conserved domain found in hundreds of mammalian proteins. PH domain–PIP3 interactions allow for rapid signal propagation and confer a spatial component to these signals. The kinases Akt and Itk are key PI3K effectors that bind PIP3 via their PH domains and mediate vital processes – such as survival, activation, and differentiation – in lymphocytes. Here, we review the roles and regulation of PI3K signaling in lymphocytes with a specific emphasis on Akt and Itk. We also discuss these and other PH domain-containing proteins as they relate more broadly to immune cell function. Finally, we highlight the emerging view of PH domains as multifunctional protein domains that often bind both lipid and protein substrates to exert their effects.
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Affiliation(s)
- Xinxin Wang
- California Institute for Biomedical Research , La Jolla, CA , USA
| | - Leonard Benjamin Hills
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth , Lebanon, NH , USA
| | - Yina Hsing Huang
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth , Lebanon, NH , USA ; Department of Pathology, Geisel School of Medicine at Dartmouth , Lebanon, NH , USA
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20
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Zhang Y, Ying J, Jiang D, Chang Z, Li H, Zhang G, Gong S, Jiang X, Tao J. Urotensin-II receptor stimulation of cardiac L-type Ca2+ channels requires the βγ subunits of Gi/o-protein and phosphatidylinositol 3-kinase-dependent protein kinase C β1 isoform. J Biol Chem 2015; 290:8644-55. [PMID: 25678708 DOI: 10.1074/jbc.m114.615021] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Recent studies have demonstrated that urotensin-II (U-II) plays important roles in cardiovascular actions including cardiac positive inotropic effects and increasing cardiac output. However, the mechanisms underlying these effects of U-II in cardiomyocytes still remain unknown. We show by electrophysiological studies that U-II dose-dependently potentiates L-type Ca(2+) currents (ICa,L) in adult rat ventricular myocytes. This effect was U-II receptor (U-IIR)-dependent and was associated with a depolarizing shift in the voltage dependence of inactivation. Intracellular application of guanosine-5'-O-(2-thiodiphosphate) and pertussis toxin pretreatment both abolished the stimulatory effects of U-II. Dialysis of cells with the QEHA peptide, but not scrambled peptide SKEE, blocked the U-II-induced response. The phosphatidylinositol 3-kinase (PI3K) inhibitor wortmannin as well as the class I PI3K antagonist CH132799 blocked the U-II-induced ICa,L response. Protein kinase C antagonists calphostin C and chelerythrine chloride as well as dialysis of cells with 1,2bis(2aminophenoxy)ethaneN,N,N',N'-tetraacetic acid abolished the U-II-induced responses, whereas PKCα inhibition or PKA blockade had no effect. Exposure of ventricular myocytes to U-II markedly increased membrane PKCβ1 expression, whereas inhibition of PKCβ1 pharmacologically or by shRNA targeting abolished the U-II-induced ICa,L response. Functionally, we observed a significant increase in the amplitude of sarcomere shortening induced by U-II; blockade of U-IIR as well as PKCβ inhibition abolished this effect, whereas Bay K8644 mimicked the U-II response. Taken together, our results indicate that U-II potentiates ICa,L through the βγ subunits of Gi/o-protein and downstream activation of the class I PI3K-dependent PKCβ1 isoform. This occurred via the activation of U-IIR and contributes to the positive inotropic effect on cardiomyocytes.
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Affiliation(s)
- Yuan Zhang
- From the Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou 215123, China, Department of Geriatrics and Institute of Neuroscience, the Second Affiliated Hospital of Soochow University, Suzhou 215004, China
| | - Jiaoqian Ying
- From the Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou 215123, China, Department of Emergency Medicine, China-Japan Friendship Hospital, Beijing 100029, China
| | - Dongsheng Jiang
- From the Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou 215123, China, Department of Dermatology and Allergic Diseases, University of Ulm, Ulm 89081, Germany, and
| | - Zhigang Chang
- From the Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou 215123, China
| | - Hua Li
- From the Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou 215123, China, National Shanghai Center for New Drug Safety Evaluation and Research, Shanghai 201203, China
| | - Guoqiang Zhang
- Department of Emergency Medicine, China-Japan Friendship Hospital, Beijing 100029, China
| | - Shan Gong
- From the Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou 215123, China
| | - Xinghong Jiang
- From the Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou 215123, China
| | - Jin Tao
- From the Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou 215123, China,
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