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Huang Y, Feng Q, Zhang Y, Zeng Y, Shi N, Chen Y, Tang X, Li Z. The effect of PDK1 in maintaining immune cell development and function. Biochem Biophys Res Commun 2024; 721:150106. [PMID: 38795634 DOI: 10.1016/j.bbrc.2024.150106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Revised: 05/07/2024] [Accepted: 05/12/2024] [Indexed: 05/28/2024]
Abstract
3-phosphoinositide-dependent protein kinase 1 (PDK1) exhibits a substantial influence on immune cell development by establishing a vital connection between PI3K and downstream mTOR signaling cascades. However, it remains unclear whether PDK1 signaling affects the homeostasis and functionality of immune cells. To explore the impact of PDK1 on different immune cells within immune organs, transgenic mouse strains with lymphocyte-specific PDK1 knockout (PDK1fl/fl CD2-Cre) were generated. Unlike wild-type (WT) mice, lymphocyte-specific PDK1 knockout (KO) mice exhibited thymic atrophy, elevated percentages of CD8+ T cells and neutrophils, and reduced proportions of γδ T cells, B cells, and NK cells in the spleen. Functional analysis revealed elevated release of IFN-γ and IL-17A by T cells in PDK1 KO mice, contrasting with diminished levels observed in γδ T cells and Treg cells. Furthermore, the activation, cytotoxicity, and migratory potential of γδ T cells in PDK1 KO mice are heightened, indicating a potential association with the regulation of the mTOR signaling pathway. To conclude, the findings of this research demonstrated that specific knockout of PDK1 in lymphocytes hindered T cell development in the thymus and exhibited a substantial influence on immune cell homeostasis in the spleen and lymph nodes.
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Affiliation(s)
- Yu Huang
- Faculty of Medical Science, Jinan University, Guangzhou 510632, China
| | - Qiuyue Feng
- Department of Systems Biomedical Sciences, School of Medicine, Jinan University, Guangzhou 510632, China
| | - Yawen Zhang
- Faculty of Medical Science, Jinan University, Guangzhou 510632, China
| | - Yingying Zeng
- Faculty of Medical Science, Jinan University, Guangzhou 510632, China
| | - Nanxi Shi
- Faculty of Medical Science, Jinan University, Guangzhou 510632, China
| | - Yiming Chen
- Faculty of Medical Science, Jinan University, Guangzhou 510632, China
| | - Xin Tang
- Guangdong Provincial Key Laboratory of Tumor Interventional Diagnosis and Treatment, Zhuhai Institute of Translational Medicine, Zhuhai People's Hospital Affiliated with Jinan University, Jinan University, Zhuhai 519000, China
| | - Zhenhua Li
- Department of Systems Biomedical Sciences, School of Medicine, Jinan University, Guangzhou 510632, China; Guangdong-Hong Kong-Macau Great Bay Area Geroscience Joint Laboratory, School of Medicine, Jinan University, Guangzhou 510632, China.
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Gd-EOB-DTPA-enhanced magnetic resonance imaging may help identify patients with hepatocellular carcinoma eligible for treatment targeted at RAF1. Abdom Radiol (NY) 2022; 47:209-220. [PMID: 34738148 DOI: 10.1007/s00261-021-03325-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Revised: 10/17/2021] [Accepted: 10/18/2021] [Indexed: 10/19/2022]
Abstract
PURPOSE The RAF1 expression affects prognosis in patients with hepatocellular carcinoma (HCC) treated with sorafenib. We examined the expression of sorafenib-targeted gene RAF1 to ascertain its relationship with gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging (MRI) characteristics. We also explored the predictive potential of RAF1 expression markers in the treatment of HCC. PATIENTS AND METHODS Sixty-five patients with HCC who underwent preoperative enhanced MRI scanning were included in this study. We analyzed the qualitative and quantitative characteristics of enhanced MRI findings in patients with HCC. Immunohistochemistry (IHC) and reverse transcription-polymerase chain reaction (RT-PCR) analyses were used to detect the protein and mRNA expression levels of RAF1 in HCC. Correlation and logistic regression analyses were used to evaluate the relationship between these image features and the RAF1 gene expression levels in HCC. RESULTS The IHC analysis indicated a significant difference in tumor thrombus group (P = 0.037), RT-PCR results revealed a significant between-group difference for both tumor margins (P = 0.033) and capsule (P = 0.04). Binary logistic regression analysis results suggest that independent MRI predictors were regular tumor margins [P = 0.035, odds ratio (OR) = 3.145, 95% confidence interval (CI) 1.087-9.103] and thrombus (P = 0.046, OR = 4.421, 95% CI 1.024-19.08) with high RAF1expression; the tumor capsule was not an independent predictor. CONCLUSION We found a correlation between MRI features and the RAF1 gene expression, Regular tumor margin and the presence of tumor thrombus are indicators of high RAF1 expression in HCC. Enhanced MRI may be useful for identifying patients with HCC eligible for targeted treatment.
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Patel P, Shaik NF, Zhou Y, Golla K, McKenzie SE, Naik UP. Apoptosis signal-regulating kinase 1 regulates immune-mediated thrombocytopenia, thrombosis, and systemic shock. J Thromb Haemost 2020; 18:3013-3028. [PMID: 32767736 PMCID: PMC7831975 DOI: 10.1111/jth.15049] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 07/07/2020] [Accepted: 07/31/2020] [Indexed: 01/07/2023]
Abstract
BACKGROUND Immune complexes (ICs) bind to and activate platelets via FcγRIIA, causing patients to experience thrombocytopenia, as well as an increased risk of forming occlusive thrombi. Although platelets have been shown to mediate IC-induced pathologies, the mechanisms involved have yet to be fully elucidated. We identified that apoptosis signal-regulating kinase 1 (ASK1) is present in both human and mouse platelets and potentiates many platelet functions. OBJECTIVES Here we set out to study ASK1's role in regulating IC-mediated platelet functions in vitro and IC-induced pathologies using an in vivo mouse model. METHODS Using human platelets treated with an ASK1-specific inhibitor and platelets from FCGR2A/Ask1-/- transgenic mice, we examined various platelet functions induced by model ICs in vitro and in vivo. RESULTS We found that ASK1 was activated in human platelets following cross-linking of FcγRIIA using either anti-hCD9 or IV.3 + goat-anti-mouse. Although genetic deletion or inhibition of ASK1 significantly attenuated anti-CD9-induced platelet aggregation, activation of the canonical FcγRIIA signaling targets Syk and PLCγ2 was unaffected. We further found that anti-mCD9-induced cPla2 phosphorylation and TxA2 generation is delayed in Ask1 null transgenic mouse platelets leading to diminished δ-granule secretion. In vivo, absence of Ask1 protected FCGR2A transgenic mice from thrombocytopenia, thrombosis, and systemic shock following injection of anti-mCD9. In whole blood microfluidics, platelet adhesion and thrombus formation on fibrinogen was enhanced by Ask1. CONCLUSIONS These findings suggest that ASK1 inhibition may be a potential target for the treatment of IC-induced shock and other immune-mediated thrombotic disorders.
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Affiliation(s)
- Pravin Patel
- Cardeza Center for Hemostasis, Thrombosis, and Vascular Biology, Cardeza Foundation for Hematologic Research, Department of Medicine, Thomas Jefferson University, Philadelphia, PA
| | - Noor F. Shaik
- Cardeza Center for Hemostasis, Thrombosis, and Vascular Biology, Cardeza Foundation for Hematologic Research, Department of Medicine, Thomas Jefferson University, Philadelphia, PA
| | - Yuhang Zhou
- Cardeza Center for Hemostasis, Thrombosis, and Vascular Biology, Cardeza Foundation for Hematologic Research, Department of Medicine, Thomas Jefferson University, Philadelphia, PA
- Dell Children’s Hospital, University of Texas, Austin, TX
| | - Kalyan Golla
- Cardeza Center for Hemostasis, Thrombosis, and Vascular Biology, Cardeza Foundation for Hematologic Research, Department of Medicine, Thomas Jefferson University, Philadelphia, PA
- Center for Blood Research, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Steven E. McKenzie
- Cardeza Center for Hemostasis, Thrombosis, and Vascular Biology, Cardeza Foundation for Hematologic Research, Department of Medicine, Thomas Jefferson University, Philadelphia, PA
| | - Ulhas P. Naik
- Cardeza Center for Hemostasis, Thrombosis, and Vascular Biology, Cardeza Foundation for Hematologic Research, Department of Medicine, Thomas Jefferson University, Philadelphia, PA
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Patel P, Naik UP. Platelet MAPKs-a 20+ year history: What do we really know? J Thromb Haemost 2020; 18:2087-2102. [PMID: 32574399 DOI: 10.1111/jth.14967] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 06/09/2020] [Accepted: 06/10/2020] [Indexed: 01/01/2023]
Abstract
The existence of mitogen activated protein kinases (MAPKs) in platelets has been known for more than 20 years. Since that time hundreds of reports have been published describing the conditions that cause MAPK activation in platelets and their role in regulating diverse platelet functions from the molecular to physiological level. However, this cacophony of reports, with inconsistent and sometimes contradictory findings, has muddied the waters leading to great confusion. Since the last review of platelet MAPKs was published more than a decade ago, there have been more than 50 reports, including the description of novel knockout mouse models, that have furthered our knowledge. Therefore, we undertook an extensive literature review to delineate what is known about platelet MAPKs. We specifically discuss what is currently known about how MAPKs are activated and what signaling cascades they regulate in platelets incorporating recent findings from knockout mouse models. In addition, we will discuss the role each MAPK plays in regulating distinct platelet functions. In doing so, we hope to clarify the role for MAPKs and identify knowledge gaps in this field that await future researchers. In addition, we discuss the limitations of current studies with a particular focus on the off-target effects of commonly used MAPK inhibitors. We conclude with a look at the clinical utility of MAPK inhibitors as potential antithrombotic therapies with an analysis of current clinical trial data.
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Affiliation(s)
- Pravin Patel
- Department of Medicine, Cardeza Center for Hemostasis, Thrombosis, and Vascular Biology, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA, USA
| | - Ulhas P Naik
- Department of Medicine, Cardeza Center for Hemostasis, Thrombosis, and Vascular Biology, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA, USA
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Calcium-induced dissociation of CIB1 from ASK1 regulates agonist-induced activation of the p38 MAPK pathway in platelets. Biochem J 2020; 476:2835-2850. [PMID: 31530712 DOI: 10.1042/bcj20190410] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 09/10/2019] [Accepted: 09/16/2019] [Indexed: 12/14/2022]
Abstract
Apoptosis signal-regulating kinase 1 (ASK1) is a mitogen-activated protein kinase kinase kinase (MAPKKK) that regulates activation of the c-Jun N-terminal kinase (JNK)- and p38-stress response pathways leading to apoptosis in nucleated cells. We have previously shown that ASK1 is expressed in platelets and regulates agonist-induced platelet activation and thrombosis. However, the mechanism by which platelet agonists cause activation of ASK1 is unknown. Here, we show that in platelets agonist-induced activation of p38 is exclusively dependent on ASK1. Both thrombin and collagen were able to activate ASK1/p38. Activation of ASK1/p38 was strongly dependent on thromboxane A2 (TxA2) and ADP. Agonist-induced ASK1 activation is blocked by inhibition of phospholipase C (PLC) β/γ activity or by chelating intracellular Ca2+. Furthermore, treatment of platelets with thapsigargin or Ca2+ ionophore robustly induced ASK1/p38 activation. In addition, calcium and integrin-binding protein 1 (CIB1), a Ca2+-dependent negative regulator of ASK1, associates with ASK1 in resting platelets and is dissociated upon platelet activation by thrombin. Dissociation of CIB1 corresponds with ASK1 binding to tumor necrosis factor (TNF) receptor associated factor 6 (TRAF6) and the autophosphorylation of ASK1 Thr838 within the catalytic domain results in full activation of ASK1. Furthermore, genetic ablation of Cib1 in mice augments agonist-induced Ask1/p38 activation. Together our results suggest that in resting platelets ASK1 is bound to CIB1 at low Ca2+ concentrations. Agonist-induced platelet activation causes an increase in intracellular Ca2+ concentration that leads to the dissociation of CIB1 from ASK1, allowing for proper dimerization through ASK1 N-terminal coiled-coil (NCC) domains.
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Manne BK, Bhatlekar S, Middleton EA, Weyrich AS, Borst O, Rondina MT. Phospho-inositide-dependent kinase 1 regulates signal dependent translation in megakaryocytes and platelets. J Thromb Haemost 2020; 18:1183-1196. [PMID: 31997536 PMCID: PMC7192796 DOI: 10.1111/jth.14748] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 12/19/2019] [Accepted: 01/27/2020] [Indexed: 12/19/2022]
Abstract
BACKGROUND Regulated protein synthesis is essential for megakaryocyte (MK) and platelet functions, including platelet production and activation. PDK1 (phosphoinositide-dependent kinase 1) regulates platelet functional responses and has been associated with circulating platelet counts. Whether PDK1 also directly regulates protein synthetic responses in MKs and platelets, and platelet production by MKs, remains unknown. OBJECTIVE To determine if PDK1 regulates protein synthesis in MKs and platelets. METHODS Pharmacologic PDK1 inhibitors (BX-795) and mice where PDK1 was selectively ablated in MKs and platelets (PDK1-/- ) were used. PDK1 signaling in MKs and platelets (human and murine) were assessed by immunoblots. Activation-dependent translation initiation and protein synthesis in MKs and platelets was assessed by probing for dissociation of eIF4E from 4EBP1, and using m7-GTP pulldowns and S35 methionine incorporation assays. Proplatelet formation by MKs, synthesis of Bcl-3 and MARCKs protein, and clot retraction were employed for functional assays. RESULTS Inhibiting or ablating PDK1 in MKs and platelets abolished the phosphorylation of 4EBP1 and eIF4E by preventing activation of the PI3K and MAPK pathways. Inhibiting PDK1 also prevented dissociation of eIF4E from 4EBP1, decreased binding of eIF4E to m7GTP (required for translation initiation), and significantly reduced de novo protein synthesis. Inhibiting PDK1 reduced proplatelet formation by human MKs and blocked MARCKs protein synthesis. In both human and murine platelets, PDK1 controlled Bcl-3 synthesis. Inhibition of PDK1 led to complete failure of clot retraction in vitro. CONCLUSIONS PDK1 is a previously unidentified translational regulator in MKs and platelets, controlling protein synthetic responses, proplatelet formation, and clot retraction.
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Affiliation(s)
- Bhanu Kanth Manne
- Department of Internal Medicine & The Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112 USA
| | - Seema Bhatlekar
- Department of Internal Medicine & The Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112 USA
| | - Elizabeth A. Middleton
- Department of Internal Medicine & The Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112 USA
| | - Andrew S. Weyrich
- Department of Internal Medicine & The Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112 USA
- Department of Pathology, University of Utah, Salt Lake City, UT, 84112 USA
| | - Oliver Borst
- Department of Cardiology and Cardiovascular Medicine, University of Tübingen, Tübingen, 72076 Germany
| | - Matthew T. Rondina
- Department of Internal Medicine & The Molecular Medicine Program, University of Utah, Salt Lake City, UT, 84112 USA
- Department of Internal Medicine, GRECC, George E. Wahlen VAMC, Salt Lake City, UT, 84148
- Department of Pathology, University of Utah, Salt Lake City, UT, 84112 USA
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