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Peters CH, Singh RK, Langley AA, Nichols WG, Ferris HR, Jeffrey DA, Proenza C, Bankston JR. LRMP inhibits cAMP potentiation of HCN4 channels by disrupting intramolecular signal transduction. eLife 2024; 12:RP92411. [PMID: 38652113 PMCID: PMC11037915 DOI: 10.7554/elife.92411] [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] [Indexed: 04/25/2024] Open
Abstract
Lymphoid restricted membrane protein (LRMP) is a specific regulator of the hyperpolarization-activated cyclic nucleotide-sensitive isoform 4 (HCN4) channel. LRMP prevents cAMP-dependent potentiation of HCN4, but the interaction domains, mechanisms of action, and basis for isoform-specificity remain unknown. Here, we identify the domains of LRMP essential for this regulation, show that LRMP acts by disrupting the intramolecular signal transduction between cyclic nucleotide binding and gating, and demonstrate that multiple unique regions in HCN4 are required for LRMP isoform-specificity. Using patch clamp electrophysiology and Förster resonance energy transfer (FRET), we identified the initial 227 residues of LRMP and the N-terminus of HCN4 as necessary for LRMP to associate with HCN4. We found that the HCN4 N-terminus and HCN4-specific residues in the C-linker are necessary for regulation of HCN4 by LRMP. Finally, we demonstrated that LRMP-regulation can be conferred to HCN2 by addition of the HCN4 N-terminus along with mutation of five residues in the S5 region and C-linker to the cognate HCN4 residues. Taken together, these results suggest that LRMP inhibits HCN4 through an isoform-specific interaction involving the N-terminals of both proteins that prevents the transduction of cAMP binding into a change in channel gating, most likely via an HCN4-specific orientation of the N-terminus, C-linker, and S4-S5 linker.
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Affiliation(s)
- Colin H Peters
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - Rohit K Singh
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical CampusAuroraUnited States
- Skaggs School of Pharmacy, Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - Avery A Langley
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - William G Nichols
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - Hannah R Ferris
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - Danielle A Jeffrey
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - Catherine Proenza
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical CampusAuroraUnited States
- Department of Medicine, Division of Cardiology, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - John R Bankston
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical CampusAuroraUnited States
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Prüschenk S, Majer M, Schlossmann J. Novel Functional Features of cGMP Substrate Proteins IRAG1 and IRAG2. Int J Mol Sci 2023; 24:9837. [PMID: 37372987 DOI: 10.3390/ijms24129837] [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: 05/12/2023] [Revised: 06/01/2023] [Accepted: 06/05/2023] [Indexed: 06/29/2023] Open
Abstract
The inositol triphosphate-associated proteins IRAG1 and IRAG2 are cGMP kinase substrate proteins that regulate intracellular Ca2+. Previously, IRAG1 was discovered as a 125 kDa membrane protein at the endoplasmic reticulum, which is associated with the intracellular Ca2+ channel IP3R-I and the PKGIβ and inhibits IP3R-I upon PKGIβ-mediated phosphorylation. IRAG2 is a 75 kDa membrane protein homolog of IRAG1 and was recently also determined as a PKGI substrate. Several (patho-)physiological functions of IRAG1 and IRAG2 were meanwhile elucidated in a variety of human and murine tissues, e.g., of IRAG1 in various smooth muscles, heart, platelets, and other blood cells, of IRAG2 in the pancreas, heart, platelets, and taste cells. Hence, lack of IRAG1 or IRAG2 leads to diverse phenotypes in these organs, e.g., smooth muscle and platelet disorders or secretory deficiency, respectively. This review aims to highlight the recent research regarding these two regulatory proteins to envision their molecular and (patho-)physiological tasks and to unravel their functional interplay as possible (patho-)physiological counterparts.
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Affiliation(s)
- Sally Prüschenk
- Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Regensburg, 93040 Regensburg, Germany
| | - Michael Majer
- Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Regensburg, 93040 Regensburg, Germany
| | - Jens Schlossmann
- Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Regensburg, 93040 Regensburg, Germany
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Kozono T, Jogano C, Okumura W, Sato H, Matsui H, Takagi T, Okumura N, Takao T, Tonozuka T, Nishikawa A. Cleavage of the Jaw1 C-terminal region enhances its augmentative effect on the Ca2+ release via IP3 receptors. J Cell Sci 2023; 136:287037. [PMID: 36789796 DOI: 10.1242/jcs.260439] [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: 08/11/2022] [Accepted: 01/17/2023] [Indexed: 02/16/2023] Open
Abstract
Jaw1 (also known as IRAG2), a tail-anchored protein with 39 carboxyl (C)-terminal amino acids, is oriented to the lumen of the endoplasmic reticulum and outer nuclear membrane. We previously reported that Jaw1, as a member of the KASH protein family, plays a role in maintaining nuclear shape via its C-terminal region. Furthermore, we recently reported that Jaw1 functions as an augmentative effector of Ca2+ release from the endoplasmic reticulum by interacting with the inositol 1,4,5-trisphosphate receptors (IP3Rs). Intriguingly, the C-terminal region is partially cleaved, meaning that Jaw1 exists in the cell in at least two forms - uncleaved and cleaved. However, the mechanism of the cleavage event and its physiological significance remain to be determined. In this study, we demonstrate that the C-terminal region of Jaw1 is cleaved after its insertion by the signal peptidase complex (SPC). Particularly, our results indicate that the SPC with the catalytic subunit SEC11A, but not SEC11C, specifically cleaves Jaw1. Furthermore, using a mutant with a defect in the cleavage event, we demonstrate that the cleavage event enhances the augmentative effect of Jaw1 on the Ca2+ release ability of IP3Rs.
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Affiliation(s)
- Takuma Kozono
- Department of Applied Biological Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Chifuyu Jogano
- Department of Applied Biological Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Wataru Okumura
- Department of Food and Energy Systems Science, Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Hiroyuki Sato
- Cooperative Major in Advanced Health Science, Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Hitomi Matsui
- Department of Applied Biological Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Tsubasa Takagi
- Department of Applied Biological Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Nobuaki Okumura
- Institute for Protein Research, Osaka University, Osaka 565-0871, Japan
| | - Toshifumi Takao
- Institute for Protein Research, Osaka University, Osaka 565-0871, Japan
| | - Takashi Tonozuka
- Department of Applied Biological Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Atsushi Nishikawa
- Department of Applied Biological Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan.,Department of Food and Energy Systems Science, Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan.,Cooperative Major in Advanced Health Science, Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
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Prüschenk S, Schlossmann J. Function of IRAG2 Is Modulated by NO/cGMP in Murine Platelets. Int J Mol Sci 2022; 23:ijms23126695. [PMID: 35743138 PMCID: PMC9223716 DOI: 10.3390/ijms23126695] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 06/08/2022] [Accepted: 06/14/2022] [Indexed: 01/27/2023] Open
Abstract
Inositol 1,4,5-triphosphate receptor-associated 2 (IRAG2) is a type II membrane protein located at the endoplasmic reticulum. It is a homologue of inositol 1,4,5-triphosphate receptor-associated cGMP kinase substrate 1 (IRAG1), a substrate protein of cGMP-dependent protein kinase I (PKGI), and is among others expressed in platelets. Here, we studied if IRAG2 is also located in platelets and might be a substrate protein of PKGI. IRAG2 was detected in platelets of IRAG2-WT animals but not in those of IRAG2-KO animals. Next, we validated by co-immunoprecipitation studies that IRAG2 is associated with IP3R1-3. No direct stable interaction with PKGIβ or with IRAG1 was observed. Phosphorylation of IRAG2 in murine platelets using a Ser/Thr-specific phospho-antibody was found in vitro and ex vivo upon cGMP stimulation. To gain insight into the function of IRAG2, platelet aggregation studies were performed using thrombin and collagen as agonists for treatment of isolated IRAG2-WT or IRAG2-KO platelets. Interestingly, platelet aggregation was reduced in the absence of IRAG2. Pretreatment of wild type or IRAG2-KO platelets with sodium nitroprusside (SNP) or 8-pCPT-cGMP revealed a further reduction in platelet aggregation in the absence of IRAG2. These results show that IRAG2 is a substrate of PKGI in murine platelets. Furthermore, our results indicate that IRAG2 is involved in the induction of thrombin- or collagen-induced platelet aggregation and that this effect is enhanced by cGMP-dependent phosphorylation of IRAG2. As IRAG1 was previously shown to inhibit platelet aggregation in a cGMP-dependent manner, it can be speculated that IRAG2 exerts an opposing function and might be an IRAG1 counterpart in murine platelets.
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Jin X, Chen L, Zhou N, Ni H, Zu L, He J, Yang L, Zhu Y, Sun X, Li X, Xu S. LRMP Associates With Immune Infiltrates and Acts as a Prognostic Biomarker in Lung Adenocarcinoma. Front Mol Biosci 2021; 8:711928. [PMID: 34901148 PMCID: PMC8661541 DOI: 10.3389/fmolb.2021.711928] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 11/05/2021] [Indexed: 11/16/2022] Open
Abstract
Background: Lymphoid-restricted membrane protein (LRMP) is an endoplasmic reticulum-associated protein that is expressed in a developmentally regulated manner in both B and T cell lineages. However, the role of LRMP in the growth, prognosis and immune infiltration in lung adenocarcinoma (LUAD) remains unclear. Method: The expression levels of LRMP mRNA in tumor and normal tissues were analyzed using Tumor Immune Estimation Resource 2.0 (TIMER 2.0) and Gene Expression Profiling Interactive Analysis 2 (GEPIA 2). LRMP protein expression was examined using the Human Protein Atlas. In vitro experiments, including qRT-PCR Western blot and immunohistochemistry staining were also performed to investigate LRMP expression. GEPIA2 and Kaplan-Meier plotter databases were used to analyze the clinical prognostic significance of LRMP. To further confirm the underlying function of LRMP, the data were analyzed using gene set enrichment analysis. Moreover, we also constructed plasmids to overexpress LRMP and explored the effect of LRMP in A549 cell line. Additionally, Tumor Immune single-cell Hub was used to investigate the distribution of LRMP in the LUAD immune microenvironment; TIMER and CIBERSORT were used to investigate the relationships among LRMP, LRMP co-expressed genes, and tumor-infiltrating immune cells; Finally, the correlations between LRMP and immune checkpoints were analyzed using TIMER 2.0. Results: The expression of LRMP was significantly lower in LUAD tissues and cell lines. High LRMP expression is associated with a better prognosis in patients with LUAD. In vitro experimental studies demonstrated that overexpression of LRMP could decrease the proliferation, migration and invasion in A549 cells, and downregulated multiple oncogenic signaling pathways, including p-STAT3, p-PI3K-p-AKT, p-MEK and EMT pathways. GSEA results showed that immuno-related and cell adhesion pathways were enriched in samples with high LRMP expression. LRMP and its co-expressed genes were positively correlated with various tumor-infiltrating immune cells and their markers. Additionally, LRMP positively correlated with immune checkpoints. Conclusions: Our data suggest that LRMP may act as a tumor suppressor gene and indicates a better prognosis. Moreover, LRMP is associated with immune infiltrates which may be involved in immunotherapy response in LUAD. Further studies are needed to validate these findings.
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Affiliation(s)
- Xin Jin
- Department of Lung Cancer Surgery, Tianjin Medical University General Hospital, Tianjin, China.,Tianjin Key Laboratory of Lung Cancer Metastasis and Tumor Microenvironment, Lung Cancer Institute, Tianjin Medical University General Hospital, Tianjin, China
| | - Liwei Chen
- Department of Oncology, First Teaching Hospital of Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Ning Zhou
- Department of Lung Cancer Surgery, Tianjin Medical University General Hospital, Tianjin, China.,Tianjin Key Laboratory of Lung Cancer Metastasis and Tumor Microenvironment, Lung Cancer Institute, Tianjin Medical University General Hospital, Tianjin, China
| | - Hong Ni
- Department of Lung Cancer Surgery, Tianjin Medical University General Hospital, Tianjin, China.,Tianjin Key Laboratory of Lung Cancer Metastasis and Tumor Microenvironment, Lung Cancer Institute, Tianjin Medical University General Hospital, Tianjin, China
| | - Lingling Zu
- Department of Lung Cancer Surgery, Tianjin Medical University General Hospital, Tianjin, China.,Tianjin Key Laboratory of Lung Cancer Metastasis and Tumor Microenvironment, Lung Cancer Institute, Tianjin Medical University General Hospital, Tianjin, China
| | - Jinling He
- Department of Lung Cancer Surgery, Tianjin Medical University General Hospital, Tianjin, China.,Tianjin Key Laboratory of Lung Cancer Metastasis and Tumor Microenvironment, Lung Cancer Institute, Tianjin Medical University General Hospital, Tianjin, China
| | - Lingqi Yang
- Department of Lung Cancer Surgery, Tianjin Medical University General Hospital, Tianjin, China.,Tianjin Key Laboratory of Lung Cancer Metastasis and Tumor Microenvironment, Lung Cancer Institute, Tianjin Medical University General Hospital, Tianjin, China
| | - Yifan Zhu
- Department of Lung Cancer Surgery, Tianjin Medical University General Hospital, Tianjin, China.,Tianjin Key Laboratory of Lung Cancer Metastasis and Tumor Microenvironment, Lung Cancer Institute, Tianjin Medical University General Hospital, Tianjin, China
| | - Xiaoyue Sun
- Department of Lung Cancer Surgery, Tianjin Medical University General Hospital, Tianjin, China.,Tianjin Key Laboratory of Lung Cancer Metastasis and Tumor Microenvironment, Lung Cancer Institute, Tianjin Medical University General Hospital, Tianjin, China
| | - Xiaojiang Li
- Department of Oncology, First Teaching Hospital of Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Song Xu
- Department of Lung Cancer Surgery, Tianjin Medical University General Hospital, Tianjin, China.,Tianjin Key Laboratory of Lung Cancer Metastasis and Tumor Microenvironment, Lung Cancer Institute, Tianjin Medical University General Hospital, Tianjin, China
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Prüschenk S, Majer M, Schreiber R, Schlossmann J. IRAG2 Interacts with IP 3-Receptor Types 1, 2, and 3 and Regulates Intracellular Ca 2+ in Murine Pancreatic Acinar Cells. Int J Mol Sci 2021; 22:ijms222413409. [PMID: 34948204 PMCID: PMC8707672 DOI: 10.3390/ijms222413409] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [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: 11/24/2021] [Revised: 12/10/2021] [Accepted: 12/11/2021] [Indexed: 01/18/2023] Open
Abstract
The inositol 1,4,5-triphosphate receptor-associated 2 (IRAG2) is also known as Jaw1 or lymphoid-restricted membrane protein (LRMP) and shares homology with the inositol 1,4,5-triphosphate receptor-associated cGMP kinase substrate 1 (IRAG1). IRAG1 interacts with inositol trisphosphate receptors (IP3 receptors /IP3R) via its coiled-coil domain and modulates Ca2+ release from intracellular stores. Due to the homology of IRAG1 and IRAG2, especially in its coiled-coil domain, it is possible that IRAG2 has similar interaction partners like IRAG1 and that IRAG2 also modulates intracellular Ca2+ signaling. In our study, we localized IRAG2 in pancreatic acinar cells of the exocrine pancreas, and we investigated the interaction of IRAG2 with IP3 receptors and its impact on intracellular Ca2+ signaling and exocrine pancreatic function, like amylase secretion. We detected the interaction of IRAG2 with different subtypes of IP3R and altered Ca2+ release in pancreatic acinar cells from mice lacking IRAG2. IRAG2 deficiency decreased basal levels of intracellular Ca2+, suggesting that IRAG2 leads to activation of IP3R under unstimulated basal conditions. Moreover, we observed that loss of IRAG2 impacts the secretion of amylase. Our data, therefore, suggest that IRAG2 modulates intracellular Ca2+ signaling, which regulates exocrine pancreatic function.
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Affiliation(s)
- Sally Prüschenk
- Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Regensburg, 93040 Regensburg, Germany; (S.P.); (M.M.)
| | - Michael Majer
- Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Regensburg, 93040 Regensburg, Germany; (S.P.); (M.M.)
| | - Rainer Schreiber
- Institute of Physiology, University of Regensburg, 93040 Regensburg, Germany;
| | - Jens Schlossmann
- Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Regensburg, 93040 Regensburg, Germany; (S.P.); (M.M.)
- Correspondence: ; Tel.: +49-941-943-4770
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Peters CH, Myers ME, Juchno J, Haimbaugh C, Bichraoui H, Du Y, Bankston JR, Walker LA, Proenza C. Isoform-specific regulation of HCN4 channels by a family of endoplasmic reticulum proteins. Proc Natl Acad Sci U S A 2020; 117:18079-90. [PMID: 32647060 DOI: 10.1073/pnas.2006238117] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Ion channels in excitable cells function in macromolecular complexes in which auxiliary proteins modulate the biophysical properties of the pore-forming subunits. Hyperpolarization-activated, cyclic nucleotide-sensitive HCN4 channels are critical determinants of membrane excitability in cells throughout the body, including thalamocortical neurons and cardiac pacemaker cells. We previously showed that the properties of HCN4 channels differ dramatically in different cell types, possibly due to the endogenous expression of auxiliary proteins. Here, we report the discovery of a family of endoplasmic reticulum (ER) transmembrane proteins that associate with and modulate HCN4. Lymphoid-restricted membrane protein (LRMP, Jaw1) and inositol trisphosphate receptor-associated guanylate kinase substrate (IRAG, Mrvi1, and Jaw1L) are homologous proteins with small ER luminal domains and large cytoplasmic domains. Despite their homology, LRMP and IRAG have distinct effects on HCN4. LRMP is a loss-of-function modulator that inhibits the canonical depolarizing shift in the voltage dependence of HCN4 in response to the binding of cAMP. In contrast, IRAG causes a gain of HCN4 function by depolarizing the basal voltage dependence in the absence of cAMP. The mechanisms of action of LRMP and IRAG are independent of trafficking and cAMP binding, and they are specific to the HCN4 isoform. We also found that IRAG is highly expressed in the mouse sinoatrial node where computer modeling predicts that its presence increases HCN4 current. Our results suggest important roles for LRMP and IRAG in the regulation of cellular excitability, as tools for advancing mechanistic understanding of HCN4 channel function, and as possible scaffolds for coordination of signaling pathways.
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Paul AG, Chandran B, Sharma-Walia N. Cyclooxygenase-2-prostaglandin E2-eicosanoid receptor inflammatory axis: a key player in Kaposi's sarcoma-associated herpes virus associated malignancies. Transl Res 2013; 162:77-92. [PMID: 23567332 PMCID: PMC7185490 DOI: 10.1016/j.trsl.2013.03.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 02/13/2013] [Accepted: 03/15/2013] [Indexed: 12/28/2022]
Abstract
The role of cyclooxygenase-2 (COX-2), its lipid metabolite prostaglandin E2 (PGE2), and Eicosanoid (EP) receptors (EP; 1-4) underlying the proinflammatory mechanistic aspects of Burkitt's lymphoma, nasopharyngeal carcinoma, cervical cancer, prostate cancer, colon cancer, and Kaposi's sarcoma (KS) is an active area of investigation. The tumorigenic potential of COX-2 and PGE2 through EP receptors forms the mechanistic context underlying the chemotherapeutic potential of nonsteroidal anti-inflammatory drugs (NSAIDs). Although role of the COX-2 is described in several viral associated malignancies, the biological significance of the COX-2/PGE2/EP receptor inflammatory axis is extensively studied only in Kaposi's sarcoma-associated herpes virus (KSHV/HHV-8) associated malignancies such as KS, a multifocal endothelial cell tumor and primary effusion lymphoma (PEL), a B cell-proliferative disorder. The purpose of this review is to summarize the salient findings delineating the molecular mechanisms downstream of COX-2 involving PGE2 secretion and its autocrine and paracrine interactions with EP receptors (EP1-4), COX-2/PGE2/EP receptor signaling regulating KSHV pathogenesis and latency. KSHV infection induces COX-2, PGE2 secretion, and EP receptor activation. The resulting signal cascades modulate the expression of KSHV latency genes (latency associated nuclear antigen-1 [LANA-1] and viral-Fas (TNFRSF6)-associated via death domain like interferon converting enzyme-like- inhibitory protein [vFLIP]). vFLIP was also shown to be crucial for the maintenance of COX-2 activation. The mutually interdependent interactions between viral proteins (LANA-1/vFLIP) and COX-2/PGE2/EP receptors was shown to play key roles in the biological mechanisms involved in KS and PEL pathogenesis such as blockage of apoptosis, cell cycle regulation, transformation, proliferation, angiogenesis, adhesion, invasion, and immune-suppression. Understanding the COX-2/PGE2/EP axis is very important to develop new safer and specific therapeutic modalities for KS and PEL. In addition to COX-2 being a therapeutic target, EP receptors represent ideal targets for pharmacologic agents as PGE2 analogues and their blockers/antagonists possess antineoplastic activity, without the reported gastrointestinal and cardiovascular toxicity observed with few a NSAIDs.
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MESH Headings
- Anti-Inflammatory Agents, Non-Steroidal/pharmacology
- Antineoplastic Agents/pharmacology
- Cyclooxygenase 2/metabolism
- Dinoprostone/metabolism
- Gene Expression Regulation, Viral
- Herpesvirus 8, Human/genetics
- Herpesvirus 8, Human/pathogenicity
- Humans
- Lymphoma, Primary Effusion/drug therapy
- Lymphoma, Primary Effusion/metabolism
- Receptors, Eicosanoid/metabolism
- Sarcoma, Kaposi/drug therapy
- Sarcoma, Kaposi/metabolism
- Sarcoma, Kaposi/virology
- Signal Transduction
- Virus Latency/genetics
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Affiliation(s)
- Arun George Paul
- H. M. Bligh Cancer Research Laboratories, Department of Microbiology and Immunology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Ill
| | - Bala Chandran
- H. M. Bligh Cancer Research Laboratories, Department of Microbiology and Immunology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Ill
| | - Neelam Sharma-Walia
- H. M. Bligh Cancer Research Laboratories, Department of Microbiology and Immunology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, Ill
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