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Lui VG, Ghosh T, Rymaszewski A, Chen S, Baxter RM, Kong DS, Ghosh D, Routes JM, Verbsky JW, Hsieh EWY. Dysregulated Lymphocyte Antigen Receptor Signaling in Common Variable Immunodeficiency with Granulomatous Lymphocytic Interstitial Lung Disease. J Clin Immunol 2023; 43:1311-1325. [PMID: 37093407 PMCID: PMC10524976 DOI: 10.1007/s10875-023-01485-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Accepted: 04/04/2023] [Indexed: 04/25/2023]
Abstract
PURPOSE A subset of common variable immunodeficiency (CVID) patients either presents with or develops autoimmune and lymphoproliferative complications, such as granulomatous lymphocytic interstitial lung disease (GLILD), a major cause of morbidity and mortality in CVID. While a myriad of phenotypic lymphocyte derangements has been associated with and described in GLILD, defects in T and B cell antigen receptor (TCR/BCR) signaling in CVID and CVID with GLILD (CVID/GLILD) remain undefined, hindering discovery of biomarkers for disease monitoring, prognostic prediction, and personalized medicine approaches. METHODS To identify perturbations of immune cell subsets and TCR/BCR signal transduction, we applied mass cytometry analysis to peripheral blood mononuclear cells (PBMCs) from healthy control participants (HC), CVID, and CVID/GLILD patients. RESULTS Patients with CVID, regardless of GLILD status, had increased frequency of HLADR+CD4+ T cells, CD57+CD8+ T cells, and CD21lo B cells when compared to healthy controls. Within these cellular populations in CVID/GLILD patients only, engagement of T or B cell antigen receptors resulted in discordant downstream signaling responses compared to CVID. In CVID/GLILD patients, CD21lo B cells showed perturbed BCR-mediated phospholipase C gamma and extracellular signal-regulated kinase activation, while HLADR+CD4+ T cells and CD57+CD8+ T cells displayed disrupted TCR-mediated activation of kinases most proximal to the receptor. CONCLUSION Both CVID and CVID/GLILD patients demonstrate an activated T and B cell phenotype compared to HC. However, only CVID/GLILD patients exhibit altered TCR/BCR signaling in the activated lymphocyte subsets. These findings contribute to our understanding of the mechanisms of immune dysregulation in CVID with GLILD.
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Affiliation(s)
- Victor G Lui
- Department of Immunology and Microbiology, School of Medicine, University of Colorado, 12800 East 19Th Ave, Mail Stop 8333, RC1 North P18-8117, Aurora, CO, 80045, USA
| | - Tusharkanti Ghosh
- Department of Biostatistics and Informatics, School of Public Health, University of Colorado, Aurora, CO, USA
| | - Amy Rymaszewski
- Division of Allergy and Clinical Immunology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Shaoying Chen
- Division of Rheumatology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, USA
- Division of Asthma, Allergy, and Clinical Immunology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Ryan M Baxter
- Department of Immunology and Microbiology, School of Medicine, University of Colorado, 12800 East 19Th Ave, Mail Stop 8333, RC1 North P18-8117, Aurora, CO, 80045, USA
| | - Daniel S Kong
- Department of Immunology and Microbiology, School of Medicine, University of Colorado, 12800 East 19Th Ave, Mail Stop 8333, RC1 North P18-8117, Aurora, CO, 80045, USA
| | - Debashis Ghosh
- Department of Biostatistics and Informatics, School of Public Health, University of Colorado, Aurora, CO, USA
| | - John M Routes
- Division of Allergy and Clinical Immunology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, USA
- Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, USA
| | - James W Verbsky
- Division of Rheumatology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, USA
- Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Elena W Y Hsieh
- Department of Immunology and Microbiology, School of Medicine, University of Colorado, 12800 East 19Th Ave, Mail Stop 8333, RC1 North P18-8117, Aurora, CO, 80045, USA.
- Department of Pediatrics, Section of Allergy and Immunology, School of Medicine, University of Colorado, Aurora, CO, USA.
- Children's Hospital Colorado, Aurora, CO, USA.
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Le Coz C, Nguyen DN, Su C, Nolan BE, Albrecht AV, Xhani S, Sun D, Demaree B, Pillarisetti P, Khanna C, Wright F, Chen PA, Yoon S, Stiegler AL, Maurer K, Garifallou JP, Rymaszewski A, Kroft SH, Olson TS, Seif AE, Wertheim G, Grant SFA, Vo LT, Puck JM, Sullivan KE, Routes JM, Zakharova V, Shcherbina A, Mukhina A, Rudy NL, Hurst ACE, Atkinson TP, Boggon TJ, Hakonarson H, Abate AR, Hajjar J, Nicholas SK, Lupski JR, Verbsky J, Chinn IK, Gonzalez MV, Wells AD, Marson A, Poon GMK, Romberg N. Constrained chromatin accessibility in PU.1-mutated agammaglobulinemia patients. J Exp Med 2021; 218:212070. [PMID: 33951726 PMCID: PMC8105723 DOI: 10.1084/jem.20201750] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 02/09/2021] [Accepted: 03/16/2021] [Indexed: 12/19/2022] Open
Abstract
The pioneer transcription factor (TF) PU.1 controls hematopoietic cell fate by decompacting stem cell heterochromatin and allowing nonpioneer TFs to enter otherwise inaccessible genomic sites. PU.1 deficiency fatally arrests lymphopoiesis and myelopoiesis in mice, but human congenital PU.1 disorders have not previously been described. We studied six unrelated agammaglobulinemic patients, each harboring a heterozygous mutation (four de novo, two unphased) of SPI1, the gene encoding PU.1. Affected patients lacked circulating B cells and possessed few conventional dendritic cells. Introducing disease-similar SPI1 mutations into human hematopoietic stem and progenitor cells impaired early in vitro B cell and myeloid cell differentiation. Patient SPI1 mutations encoded destabilized PU.1 proteins unable to nuclear localize or bind target DNA. In PU.1-haploinsufficient pro–B cell lines, euchromatin was less accessible to nonpioneer TFs critical for B cell development, and gene expression patterns associated with the pro– to pre–B cell transition were undermined. Our findings molecularly describe a novel form of agammaglobulinemia and underscore PU.1’s critical, dose-dependent role as a hematopoietic euchromatin gatekeeper.
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Affiliation(s)
- Carole Le Coz
- Division of Immunology and Allergy, Children's Hospital of Philadelphia, Philadelphia, PA
| | - David N Nguyen
- Division of Infectious Diseases, Department of Medicine, University of California San Francisco, San Francisco, CA.,Department of Microbiology and Immunology, University of California San Francisco, San Francisco, CA.,Diabetes Center, University of California San Francisco, San Francisco, CA.,Innovative Genomics Institute, University of California Berkeley, Berkeley, CA.,Gladstone-University of California San Francisco Institute of Genomic Immunology, San Francisco, CA
| | - Chun Su
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, PA.,Center for Spatial and Functional Genomics, Children's Hospital of Philadelphia, Philadelphia, PA
| | - Brian E Nolan
- Division of Rheumatology, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL.,Department of Pediatrics, Feinberg School of Medicine, Northwestern University, Chicago, IL
| | - Amanda V Albrecht
- Department of Chemistry and Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA
| | - Suela Xhani
- Department of Chemistry and Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA
| | - Di Sun
- Division of Immunology and Allergy, Children's Hospital of Philadelphia, Philadelphia, PA
| | - Benjamin Demaree
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA.,University of California Berkeley-University of California San Francisco Graduate Program in Bioengineering, University of California, San Francisco, CA
| | - Piyush Pillarisetti
- Division of Immunology and Allergy, Children's Hospital of Philadelphia, Philadelphia, PA
| | - Caroline Khanna
- Division of Immunology and Allergy, Children's Hospital of Philadelphia, Philadelphia, PA
| | - Francis Wright
- Division of Infectious Diseases, Department of Medicine, University of California San Francisco, San Francisco, CA.,Department of Microbiology and Immunology, University of California San Francisco, San Francisco, CA
| | - Peixin Amy Chen
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, CA.,Diabetes Center, University of California San Francisco, San Francisco, CA.,Innovative Genomics Institute, University of California Berkeley, Berkeley, CA.,Gladstone-University of California San Francisco Institute of Genomic Immunology, San Francisco, CA
| | - Samuel Yoon
- Division of Immunology and Allergy, Children's Hospital of Philadelphia, Philadelphia, PA
| | - Amy L Stiegler
- Departments of Pharmacology, Yale University, New Haven, CT
| | - Kelly Maurer
- Division of Immunology and Allergy, Children's Hospital of Philadelphia, Philadelphia, PA
| | - James P Garifallou
- Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, PA
| | - Amy Rymaszewski
- Division of Allergy and Immunology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI
| | - Steven H Kroft
- Department of Pathology, Medical College of Wisconsin, Milwaukee, WI
| | - Timothy S Olson
- Division of Oncology, Children's Hospital of Philadelphia, Philadelphia, PA.,Department of Pediatrics, Perelman School of Medicine, Philadelphia, PA
| | - Alix E Seif
- Division of Oncology, Children's Hospital of Philadelphia, Philadelphia, PA.,Department of Pediatrics, Perelman School of Medicine, Philadelphia, PA
| | - Gerald Wertheim
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA.,Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Struan F A Grant
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, PA.,Department of Pediatrics, Perelman School of Medicine, Philadelphia, PA.,Division of Diabetes and Endocrinology, Children's Hospital of Philadelphia, Philadelphia, PA.,Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Linda T Vo
- Diabetes Center, University of California San Francisco, San Francisco, CA.,Innovative Genomics Institute, University of California Berkeley, Berkeley, CA
| | - Jennifer M Puck
- Division of Allergy, Immunology, and Bone Marrow Transplantation, Department of Pediatrics, University of California, San Francisco, CA.,University of California San Francsico Institute for Human Genetics and Smith Cardiovascular Research Institute, University of California, San Francisco, CA.,UCSF Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, CA
| | - Kathleen E Sullivan
- Division of Immunology and Allergy, Children's Hospital of Philadelphia, Philadelphia, PA.,Department of Pediatrics, Perelman School of Medicine, Philadelphia, PA.,Institute for Immunology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - John M Routes
- Division of Allergy and Immunology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI
| | - Viktoria Zakharova
- Laboratory of Molecular Biology, Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, Russia
| | - Anna Shcherbina
- Department of Immunology, Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, Russia
| | - Anna Mukhina
- Department of Immunology, Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, Russia
| | - Natasha L Rudy
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL
| | - Anna C E Hurst
- Department of Genetics, University of Alabama at Birmingham, Birmingham, AL.,Department of Pediatrics, University of Alabama at Birmingham, Birmingham, AL
| | - T Prescott Atkinson
- Department of Pediatrics, University of Alabama at Birmingham, Birmingham, AL
| | - Titus J Boggon
- Departments of Pharmacology, Yale University, New Haven, CT.,Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT
| | - Hakon Hakonarson
- Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, PA.,Department of Pediatrics, Perelman School of Medicine, Philadelphia, PA
| | - Adam R Abate
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA.,University of California Berkeley-University of California San Francisco Graduate Program in Bioengineering, University of California, San Francisco, CA.,Chan Zuckerberg Biohub, San Francisco, CA
| | - Joud Hajjar
- William T. Shearer Center for Human Immunobiology, Texas Children's Hospital, Houston, TX.,Department of Immunology, Allergy and Rheumatology, Baylor College of Medicine, Houston, TX
| | - Sarah K Nicholas
- William T. Shearer Center for Human Immunobiology, Texas Children's Hospital, Houston, TX.,Department of Immunology, Allergy and Rheumatology, Baylor College of Medicine, Houston, TX
| | - James R Lupski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX.,Texas Children's Hospital, Houston, TX.,Baylor-Hopkins Center for Mendelian Genomics, Houston, TX
| | - James Verbsky
- Division of Allergy and Immunology, Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI
| | - Ivan K Chinn
- William T. Shearer Center for Human Immunobiology, Texas Children's Hospital, Houston, TX.,Department of Immunology, Allergy and Rheumatology, Baylor College of Medicine, Houston, TX
| | - Michael V Gonzalez
- Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, PA
| | - Andrew D Wells
- Center for Spatial and Functional Genomics, Children's Hospital of Philadelphia, Philadelphia, PA.,Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA.,Institute for Immunology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Alex Marson
- Division of Infectious Diseases, Department of Medicine, University of California San Francisco, San Francisco, CA.,Department of Microbiology and Immunology, University of California San Francisco, San Francisco, CA.,Diabetes Center, University of California San Francisco, San Francisco, CA.,Innovative Genomics Institute, University of California Berkeley, Berkeley, CA.,Gladstone-University of California San Francisco Institute of Genomic Immunology, San Francisco, CA.,Chan Zuckerberg Biohub, San Francisco, CA.,Parker Institute for Cancer Immunotherapy, San Francisco, CA
| | - Gregory M K Poon
- Department of Chemistry and Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA
| | - Neil Romberg
- Division of Immunology and Allergy, Children's Hospital of Philadelphia, Philadelphia, PA.,Department of Pediatrics, Perelman School of Medicine, Philadelphia, PA.,Institute for Immunology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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3
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Bergom C, Straza MW, Rymaszewski A, Frei A, Lemke A, Schlaak RA, Tsaih SW, Flister MJ. Abstract IA004: Genetic variants in the tumor microenvironment alter radiation responses in breast cancer. Cancer Res 2021. [DOI: 10.1158/1538-7445.tme21-ia004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Objectives: The tumor microenvironment (TME) can impact breast cancer tumor growth, progression, and treatment responses. Data suggests that genetic variants in not only breast cancer cells, but also in the TME, can also alter these processes. We have utilized a Consomic Xenograft Model (CXM), which maps germline variants that impact only the TME, as well as a species-specific RNA-seq (SSRS) protocol which allows detection of expression changes in the malignant and nonmalignant cellular compartments of tumor xenografts, in parallel to identify genetic variants in the TME that affect radiation sensitivity. Materials/Methods: Human triple negative breast cancer MDA-MD-231 cells were implanted into immunodeficient (IL2RG KO) consomic rat strains that are genetically identical except for chromosome 3 is inherited from a separate strain (SS and SS.BN3 strains). On day 10, tumors were treated with 3 daily ionizing radiation (IR) treatments of 4 Gy or sham, and tumor growth was monitored. Tumors were also harvested for hypoxia staining using pimonidazole or for RNA-seq. RNA-Seq was performed and a custom SSRS protocol was used to align both rat and human transcripts. This yielded transcript and gene level estimated fold-change and adjusted p-values for human- and rat-derived transcripts separately. E077 mammary tumor cells were implanted into adult female immune competent C57/Bl6 mice. On day 5, tumors were treated with 5 daily IR treatments of 5 Gy or sham. Either vehicle or a mAb to the Notch ligand Dll4 (Genentech) was given twice weekly. Chi-square, Fisher’s exact, and Kolmogorov-Smirnov tests and empirical cumulative distribution plots for differential expression significance values were performed. Results: Using CXM, we discovered that BN strain-derived genetic variant(s) on rat chromosome 3 are important for tumor IR sensitivity, as human breast cancer xenografts in the consomic strain (SS.BN3) were significantly more IR sensitive than SS rat strain tumors (supra-additive). Vascular gene pathways were differentially expressed, and tumor vascular phenotypes were distinct, with SS.BN3 tumors with increased but poorly functioning blood vessels. Hypoxia was similar at baseline, but increased in SS.BN3 tumors following IR. These results were consistent with less Dll4 expression in the SS.BN3 TME. The use of a Dll4-targeted mAb in mice demonstrated that targeting Dll4 enhanced mammary tumor IR responses. Conclusion: CXM demonstrated TME genetic variants can affect IR sensitivity of genetically identical tumor cells. Using SSRS, we identified candidate genes on rat chromosome 3 that may potentially influence IR sensitivity, and our studies ultimately led to identification of the Notch ligand Dll4 as a target to enhance breast cancer IR responses. Future studies will investigate the possibility of the Dll4 pathway as a therapeutic target, as well as interrogate other pathways responsible for changes in IR sensitivity seen in the CXM model. Determining TME factors that affect the IR sensitivity will allow more tailored and effective treatments.
Citation Format: Carmen Bergom, Michael W. Straza, Amy Rymaszewski, Anne Frei, Angela Lemke, Rachel A. Schlaak, Shirng-Wern Tsaih, Michael J. Flister. Genetic variants in the tumor microenvironment alter radiation responses in breast cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference on the Evolving Tumor Microenvironment in Cancer Progression: Mechanisms and Emerging Therapeutic Opportunities; in association with the Tumor Microenvironment (TME) Working Group; 2021 Jan 11-12. Philadelphia (PA): AACR; Cancer Res 2021;81(5 Suppl):Abstract nr IA004.
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Affiliation(s)
| | | | | | - Anne Frei
- 2Medical College of Wisconsin, Milwaukee, WI
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4
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Verbsky JW, Hintermeyer MK, Simpson PM, Feng M, Barbeau J, Rao N, Cool CD, Sosa-Lozano LA, Baruah D, Hammelev E, Busalacchi A, Rymaszewski A, Woodliff J, Chen S, Bausch-Jurken M, Routes JM. Rituximab and antimetabolite treatment of granulomatous and lymphocytic interstitial lung disease in common variable immunodeficiency. J Allergy Clin Immunol 2020; 147:704-712.e17. [PMID: 32745555 DOI: 10.1016/j.jaci.2020.07.021] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 07/08/2020] [Accepted: 07/16/2020] [Indexed: 12/15/2022]
Abstract
BACKGROUND Granulomatous and lymphocytic interstitial lung disease (GLILD) is a life-threatening complication in patients with common variable immunodeficiency (CVID), but the optimal treatment is unknown. OBJECTIVE Our aim was to determine whether rituximab with azathioprine or mycophenolate mofetil improves the high-resolution computed tomography (HRCT) chest scans and/or pulmonary function test results in patients with CVID and GLILD. METHODS A retrospective chart review of clinical and laboratory data on 39 patients with CVID and GLILD who completed immunosuppressive therapy was performed. Chest HRCT scans, performed before therapy and after the conclusion of therapy, were blinded, randomized, and scored independently by 2 radiologists. Differences between pretreatment and posttreatment HRCT scan scores, pulmonary function test results, and lymphocyte subsets were analyzed. Whole exome sequencing was performed on all patients. RESULTS Immunosuppressive therapy improved patients' HRCT scan scores (P < .0001), forced vital capacity (P = .0017), FEV1 (P = .037), and total lung capacity (P = .013) but not their lung carbon monoxide diffusion capacity (P = .12). Nine patients relapsed and 6 completed retreatment, with 5 of 6 of these patients (83%) having improved HRCT scan scores (P = .063). Relapse was associated with an increased number of B cells (P = .016) and activated CD4 T cells (P = .016). Four patients (10%) had pneumonia while undergoing active treatment, and 2 patients (5%) died after completion of therapy. Eight patients (21%) had a damaging mutation in a gene known to predispose (TNFRSF13B [n = 3]) or cause a CVID-like primary immunodeficiency (CTLA4 [n = 2], KMT2D [n = 2], or BIRC4 [n = 1]). Immunosuppression improved the HRCT scan scores in patients with (P = .0078) and without (P < .0001) a damaging mutation. CONCLUSIONS Immunosuppressive therapy improved the radiographic abnormalities and pulmonary function of patients with GLILD. A majority of patients had sustained remissions.
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Affiliation(s)
- James W Verbsky
- Division of Pediatric Rheumatology, Medical College Wisconsin, Milwaukee, Wis; Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wis
| | - Mary K Hintermeyer
- Asthma, Allergy and Clinical Immunology, Children's Wisconsin, Milwaukee, Wis
| | - Pippa M Simpson
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wis; Department of Quantitative Health Sciences, Medical College Wisconsin, Milwaukee, Wis
| | - Mingen Feng
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wis; Department of Quantitative Health Sciences, Medical College Wisconsin, Milwaukee, Wis
| | - Jody Barbeau
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wis; Department of Quantitative Health Sciences, Medical College Wisconsin, Milwaukee, Wis
| | - Nagarjun Rao
- Department of Pathology, Aurora Clinical Laboratories/Great Lakes Pathologists, Aurora West Allis Medical Center, West Allis, Wis
| | - Carlyne D Cool
- Department of Pathology and Division of Pulmonary and Critical Care Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colo; National Jewish Health, Denver, Colo
| | - Luis A Sosa-Lozano
- Division of Diagnostic Radiology, Medical College of Wisconsin, Milwaukee, Wis
| | - Dhiraj Baruah
- Division of Thoracic Radiology, Medical University of South Carolina, Charleston, SC
| | - Erin Hammelev
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wis; Division of Asthma, Allergy and Clinical Immunology, Medical College of Wisconsin, Milwaukee, Wis
| | - Alyssa Busalacchi
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wis; Division of Asthma, Allergy and Clinical Immunology, Medical College of Wisconsin, Milwaukee, Wis
| | - Amy Rymaszewski
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wis; Division of Asthma, Allergy and Clinical Immunology, Medical College of Wisconsin, Milwaukee, Wis
| | - Jeff Woodliff
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wis; Division of Asthma, Allergy and Clinical Immunology, Medical College of Wisconsin, Milwaukee, Wis
| | - Shaoying Chen
- Division of Pediatric Rheumatology, Medical College Wisconsin, Milwaukee, Wis; Division of Asthma, Allergy and Clinical Immunology, Medical College of Wisconsin, Milwaukee, Wis
| | - Mary Bausch-Jurken
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wis; Division of Asthma, Allergy and Clinical Immunology, Medical College of Wisconsin, Milwaukee, Wis
| | - John M Routes
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wis; Division of Asthma, Allergy and Clinical Immunology, Medical College of Wisconsin, Milwaukee, Wis.
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5
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Yang C, Siebert JR, Burns R, Gerbec ZJ, Bonacci B, Rymaszewski A, Rau M, Riese MJ, Rao S, Carlson KS, Routes JM, Verbsky JW, Thakar MS, Malarkannan S. Heterogeneity of human bone marrow and blood natural killer cells defined by single-cell transcriptome. Nat Commun 2019; 10:3931. [PMID: 31477722 PMCID: PMC6718415 DOI: 10.1038/s41467-019-11947-7] [Citation(s) in RCA: 136] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Accepted: 08/09/2019] [Indexed: 12/21/2022] Open
Abstract
Natural killer (NK) cells are critical to both innate and adaptive immunity. However, the development and heterogeneity of human NK cells are yet to be fully defined. Using single-cell RNA-sequencing technology, here we identify distinct NK populations in human bone marrow and blood, including one population expressing higher levels of immediate early genes indicative of a homeostatic activation. Functionally matured NK cells with high expression of CX3CR1, HAVCR2 (TIM-3), and ZEB2 represents terminally differentiated status with the unique transcriptional profile. Transcriptomic and pseudotime analyses identify a transitional population between CD56bright and CD56dim NK cells. Finally, a donor with GATA2T354M mutation exhibits reduced percentage of CD56bright NK cells with altered transcriptome and elevated cell death. These data expand our understanding of the heterogeneity and development of human NK cells. Natural killer (NK) cells are important innate immune cells with diverse functions. Here the authors use single-cell RNA-sequencing of purified human bone marrow and peripheral blood NK cells to define five populations of NK cells with distinct transcriptomic profile to further our understanding of NK development and heterogeneity.
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Affiliation(s)
- Chao Yang
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Versiti, Milwaukee, WI, USA.,Departments of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Jason R Siebert
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Versiti, Milwaukee, WI, USA.,Departments of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Robert Burns
- Bioinfomatics Core, Blood Research Institute, Versiti, Milwaukee, WI, USA
| | - Zachary J Gerbec
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Versiti, Milwaukee, WI, USA.,Departments of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Benedetta Bonacci
- Flow Cytometry Core, Blood Research Institute, Versiti, Milwaukee, WI, USA
| | - Amy Rymaszewski
- Departments of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Mary Rau
- Departments of Surgery, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Matthew J Riese
- Departments of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, USA.,Laboratory of Lymphocyte Biology, Blood Research Institute, Versiti, Milwaukee, WI, USA.,Departments of Medicine, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Sridhar Rao
- Departments of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, USA.,Laboratory of Stem Cell Transcriptional Regulation, Blood Research Institute, Versiti, Milwaukee, WI, USA.,Departments of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Karen-Sue Carlson
- Departments of Medicine, Medical College of Wisconsin, Milwaukee, WI, USA.,Laboratory of Coagulation Biology, Blood Research Institute, Versiti, Milwaukee, WI, USA
| | - John M Routes
- Departments of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, USA
| | - James W Verbsky
- Departments of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Monica S Thakar
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Versiti, Milwaukee, WI, USA.,Departments of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Subramaniam Malarkannan
- Laboratory of Molecular Immunology and Immunotherapy, Blood Research Institute, Versiti, Milwaukee, WI, USA. .,Departments of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, WI, USA. .,Departments of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, USA. .,Departments of Medicine, Medical College of Wisconsin, Milwaukee, WI, USA.
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6
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Straza MW, Rymaszewski A, Nickel KP, Frei A, Chatterjee A, Schlaak R, Joshi A, Flister M, Kimple RJ, Bergom C. Abstract 5898: The consomic xenograft model identifies genetic changes in the tumor microenvironment that alter the growth and metastasis of head and neck cancers. Cancer Res 2017. [DOI: 10.1158/1538-7445.am2017-5898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Background: The tumor microenvironment (TME) is known to impact tumor growth, metastatic potential, and treatment response. Nearly all studies of head and neck cancer (HNC) have focused on somatic mutations in the malignant cells. We hypothesized that genetic determinants limited to the microenvironment would influence HNC growth and metastatic potential.
Approach: To demonstrate the impact of genetic differences in the TME on HNC cell line in vivo growth we utilized a novel tool, the consomic xenograft model (CXM). A consomic rat has an entire chromosome substituted into the isogenic background of another inbred strain by selective breeding. Use of immunodeficient (IL2Rγ-/-) consomic rats allows one to study the influence of stromal genetics on tumor biology without the confounding effect of differences in the immune system through the orthotopic implantation of cancer cells into different consomic rat strains. In this system, any differences in tumor growth or metastases are due to differences in the TME rather than cancer cells or immune response. We utilized SS and SS.BN3 consomic rat strains, previously shown to affect the growth of breast tumors, to study the effects of the TME on HNC tumor growth using two well-characterized HPV negative HNC cell lines, SCC-6 (base of tongue derived) and SCC-22b (derived from a hypopharyngeal cancer that had metastasized to lymph nodes). Both cell lines were modified to stably express luciferase. HNC cells were inoculated into the tongue of SS and SS.BN3 animals and tumor growth was monitored by biophotonic imaging after luciferin injection.
Results: A significant difference in the tumor growth was seen between rat strains for both cell lines, with the SS.BN3 rats exhibiting less tumor growth and metastasis. Median luciferase activity from baseline increased by 4.1-fold vs. 1.1 fold in SCC-6 tumors in SS vs SS.BN3 rats, respectively (p<0.03). SCC-22B tumors demonstrated a significant difference in tumor size as well, with median luciferase activity from baseline 12.7 vs 4.4 fold on day 26, for SS vs SS.BN3, respectively (p<0.05). A significant differences in lung metastases was also seen between strains. Lung metastases were seen in 88% of SS and 0% of SS.BN3 rats (n=6 per group) inoculated with SCC-6 (p<0.02) and in 75% of SS and 30% of SS.BN3 rats (n=10 per group) inoculated with SCC-22b (p<0.08). Despite a non-statistically significant difference in the number of SCC-22b inoculated animals with lung metastases, there was a significantly higher metastatic burden as measured by luciferase signal, with the median signal 6.8 fold higher in SS as compared to SS.BN3 (p<0.03).
Conclusions: The use of the CXM model demonstrates an important role for the TME in the growth and metastatic spread of HNC cell lines. This model allows for future congenic mapping to identify the causative genetic variants in the TME mediating the HNC changes in tumor growth and metastasis.
Citation Format: Michael W. Straza, Amy Rymaszewski, Kwangok P. Nickel, Anne Frei, Anirban Chatterjee, Rachel Schlaak, Amit Joshi, Michael Flister, Randy J. Kimple, Carmen Bergom. The consomic xenograft model identifies genetic changes in the tumor microenvironment that alter the growth and metastasis of head and neck cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5898. doi:10.1158/1538-7445.AM2017-5898
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Affiliation(s)
| | | | | | - Anne Frei
- 1Medical College of Wisconsin, Milwaukee, WI
| | | | | | - Amit Joshi
- 1Medical College of Wisconsin, Milwaukee, WI
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Bergom C, Straza M, Rymaszewski A, Frei A, Lemke A, Tsaih SW, Jacob H, Flister MJ. Abstract B07: Utilizing consomic xenograft models to identify genetic variants in the tumor microenvironment that determine breast cancer radiation responses. Cancer Res 2016. [DOI: 10.1158/1538-7445.tme16-b07] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Progress in elucidating the molecular basis of breast cancer has allowed for treatment breakthroughs such as anti-estrogen and Her2-targeted therapy. It has also shaped the approaches to both surgical and systemic therapy. However, no similar use of molecular information has been utilized to better direct the use of radiation therapy. The development of predictive tools for the radiosensitivity of tumors could allow for personally tailored radiation doses, with treatment de-escalation for radiosensitive tumors, or dose escalation or the use of adjunct treatments in the case of radioresistant tumors. Communication between malignant tumor cells and the tumor microenvironment (TME) underlies most aspects of tumor biology, including chemotherapy and radiation resistance. We have developed a Consomic Xenograft Model (CXM), which maps germline variants that impact only the TME, as well as a species-specific RNA-seq (SSRS) protocol which allows detection of expression changes in the malignant and nonmalignant cellular compartments of tumor xenografts, in parallel and without cell-sorting. Here we utilize these unique techniques to identify genetic variants in the TME that can affect radiation sensitivity. In CXM, human triple negative breast cancer MDA-MD-231 cells are orthotopically implanted into immunodeficient (IL2Rγ-/-) consomic rat strains, which are rat strains in which an entire chromosome is introgressed into the isogenic background of another inbred strain by selective breeding. Because the strain backgrounds are different but the tumor cells are not varied, the observed changes in tumor progression are due to genetic differences in the non-malignant TME. We hypothesized that the tumors in SS.BN3 rats (identical to SS rats but with BN strain chromosome 3) would be more sensitive to radiation due to increased tumor vascularity via CD31 staining, and increased tumor blood volume capacity, as measured by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Our studies demonstrate differential responses to radiation in the CXM model comparing parental SS (IL2Rγ) rats to SS.BN3 (IL2Rγ) rats treated with fractionated radiation therapy (4 Gray x 3), with altered tumor growth kinetics and tumor recurrence rates. A difference was seen in time to 5-fold increase in tumor growth, with 44 vs. >130 days for SS versus SS.BN3 rats (supra-additive, p<0.05). There was a recurrence-free survival of 30% vs. 67% at 130 days, with a median time to recurrence of 57 days vs. time not reached (>130 days) in the SS versus SS.BN3 rats (p=0.02). These results suggest that genetic determinants in the TME affect the radiation sensitivity of genetically identical tumor cells. Using SSRS, we identified a number of candidates on rat chromosome 3 that may potentially influence radiation sensitivity by altering the tumor vasculature. Future studies will further dissect the pathways responsible for the changes in radiation sensitivity. Determining TME factors that affect the radiation sensitivity of tumors has the potential to allow for more tailored and effective radiation treatments in breast cancer.
Citation Format: Carmen Bergom, Michael Straza, Amy Rymaszewski, Anne Frei, Angela Lemke, Shirng-Wern Tsaih, Howard Jacob, Michael J. Flister. Utilizing consomic xenograft models to identify genetic variants in the tumor microenvironment that determine breast cancer radiation responses. [abstract]. In: Proceedings of the AACR Special Conference: Function of Tumor Microenvironment in Cancer Progression; 2016 Jan 7–10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2016;76(15 Suppl):Abstract nr B07.
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Affiliation(s)
| | | | | | - Anne Frei
- 1Medical College of Wisconsin, Milwaukee, WI,
| | | | | | - Howard Jacob
- 2HudsonAlpha Institute for Biotechnology, Huntsville, AL
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Rymaszewski A, Straza M, Frei A, Bergom C. Abstract 3678: The tumor suppressive small GTPase DiRas3 (ARHI) inhibits proliferation and activation of NF-κB in glioblastoma. Cancer Res 2016. [DOI: 10.1158/1538-7445.am2016-3678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Glioblastoma (GB) is the most aggressive malignancy affecting the central nervous system (CNS) with a median survival of 12 to 15 months even with surgery, radiation and chemotherapy. Previous research demonstrates that increased activation of NF-κB is critical for GB growth, proliferation and the up regulation of genes involved in cytokine production, cell cycle regulation, apoptosis and cell adhesion. Understanding the molecular targets that regulate NF-κB may provide more effective therapeutic targets for GB. DiRas family small GTPases, which are homologous to pro-oncogenic Ras GTPases, are tumor suppressive rather than tumor promoting and include DiRas1, DiRas2 and DiRas3 (ARHI). DiRas1 and DiRas2 have been suggested to be tumor suppressive in CNS malignancies, but the role of DiRas3 in CNS malignancies remains unknown. Here we demonstrate that expression of DiRas3 protein in GB cell lines is absent, although DiRas3 is expressed in non-malignant glial cells. Re-expression of DiRas3 in U-87 cells reduces cell proliferation by 20%. Using a NF-κB transcriptional activity luciferase reporter assay demonstrates that DiRas3 expression reduces NF-κB transcriptional activity by 70% compared to vector control. Further experiments demonstrate that decreased NF- κB activity occurs via reduced phosphorylation of the NF-κB inhibitor IκBα. The reduced phosphorylation of IκBα could be a result of decreased AKT and ERK activity, as increased ERK and AKT activity can stimulate NF-κB pathways. Our lab has previously demonstrated that the most common binding partner for DiRas1 and DiRas2 was the small GTPase binding protein SmgGDS, and DiRas1 and DiRas2 also reduce NF- κB activation. However, DiRas3 does not interact with SmgGDS, suggesting that DiRas3 can reduce NF-κB in a SmgGDS-independent manner. Understanding the role of DiRas3 and its binding partners in mediating NF- κB activation may lead to novel therapeutics for glioblastoma.
Citation Format: Amy Rymaszewski, Michael Straza, Anne Frei, Carmen Bergom. The tumor suppressive small GTPase DiRas3 (ARHI) inhibits proliferation and activation of NF-κB in glioblastoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3678.
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Affiliation(s)
| | | | - Anne Frei
- Medical College of Wisconsin, Milwaukee, WI
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Bergom C, Hauser AD, Rymaszewski A, Gonyo P, Prokop JW, Jennings BC, Lawton AJ, Frei A, Lorimer EL, Aguilera-Barrantes I, Mackinnon AC, Noon K, Fierke CA, Williams CL. The tumor-suppressive small GTPase DiRas1 binds the noncanonical guanine nucleotide exchange factor SmgGDS and antagonizes SmgGDS interactions with oncogenic small GTPases. J Biol Chem 2016; 291:10948. [PMID: 27197236 DOI: 10.1074/jbc.a115.696831] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Bergom C, Hauser AD, Rymaszewski A, Gonyo P, Prokop JW, Jennings BC, Lawton AJ, Frei A, Lorimer EL, Aguilera-Barrantes I, Mackinnon AC, Noon K, Fierke CA, Williams CL. The Tumor-suppressive Small GTPase DiRas1 Binds the Noncanonical Guanine Nucleotide Exchange Factor SmgGDS and Antagonizes SmgGDS Interactions with Oncogenic Small GTPases. J Biol Chem 2016; 291:6534-45. [PMID: 26814130 DOI: 10.1074/jbc.m115.696831] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Indexed: 11/06/2022] Open
Abstract
The small GTPase DiRas1 has tumor-suppressive activities, unlike the oncogenic properties more common to small GTPases such as K-Ras and RhoA. Although DiRas1 has been found to be a tumor suppressor in gliomas and esophageal squamous cell carcinomas, the mechanisms by which it inhibits malignant phenotypes have not been fully determined. In this study, we demonstrate that DiRas1 binds to SmgGDS, a protein that promotes the activation of several oncogenic GTPases. In silico docking studies predict that DiRas1 binds to SmgGDS in a manner similar to other small GTPases. SmgGDS is a guanine nucleotide exchange factor for RhoA, but we report here that SmgGDS does not mediate GDP/GTP exchange on DiRas1. Intriguingly, DiRas1 acts similarly to a dominant-negative small GTPase, binding to SmgGDS and inhibiting SmgGDS binding to other small GTPases, including K-Ras4B, RhoA, and Rap1A. DiRas1 is expressed in normal breast tissue, but its expression is decreased in most breast cancers, similar to its family member DiRas3 (ARHI). DiRas1 inhibits RhoA- and SmgGDS-mediated NF-κB transcriptional activity in HEK293T cells. We also report that DiRas1 suppresses basal NF-κB activation in breast cancer and glioblastoma cell lines. Taken together, our data support a model in which DiRas1 expression inhibits malignant features of cancers in part by nonproductively binding to SmgGDS and inhibiting the binding of other small GTPases to SmgGDS.
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Affiliation(s)
- Carmen Bergom
- From the Cancer Center, the Departments of Radiation Oncology,
| | - Andrew D Hauser
- From the Cancer Center, the Departments of Radiation Oncology, Pharmacology and Toxicology, and the Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, New York 10016, and
| | | | - Patrick Gonyo
- From the Cancer Center, Pharmacology and Toxicology, and
| | | | | | - Alexis J Lawton
- the Department of Chemistry, Biochemistry Undergraduate Program, and
| | - Anne Frei
- From the Cancer Center, the Departments of Radiation Oncology
| | | | | | | | - Kathleen Noon
- the Mass Spectroscopy Facility for Proteomics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Carol A Fierke
- the Department of Chemistry, Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109
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Vikis HG, Gelman AE, Franklin A, Stein L, Rymaszewski A, Zhu J, Liu P, Tichelaar JW, Krupnick AS, You M. Neutrophils are required for 3-methylcholanthrene-initiated, butylated hydroxytoluene-promoted lung carcinogenesis. Mol Carcinog 2011; 51:993-1002. [PMID: 22006501 DOI: 10.1002/mc.20870] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Revised: 09/06/2011] [Accepted: 09/19/2011] [Indexed: 11/11/2022]
Abstract
Multiple studies have shown a link between chronic inflammation and lung tumorigenesis. Inbred mouse strains vary in their susceptibility to methylcholanthrene (MCA)-initiated butylated hydroxytoluene (BHT)-promoted lung carcinogenesis. In the present study we investigated whether neutrophils play a role in strain dependent differences in susceptibility to lung tumor promotion. We observed a significant elevation in homeostatic levels of neutrophils in the lungs of tumor-susceptible BALB/cByJ (BALB) mice compared to tumor-resistant C57BL/6J (B6) mice. Additionally, BHT treatment further elevated neutrophil numbers as well as neutrophil chemoattractant keratinocyte-derived cytokine (KC)/chemokine (C-X-C motif) ligand 1 (Cxcl1) levels in BALB lung airways. Lung CD11c+ cells were a major source of KC expression and depletion of neutrophils in BALB mice resulted in a 71% decrease in tumor multiplicity. However, tumor multiplicity did not depend on the presence of T cells, despite the accumulation of T cells following BHT treatment. These data demonstrate that neutrophils are essential to promote tumor growth in the MCA/BHT two-step lung carcinogenesis model.
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Affiliation(s)
- Haris G Vikis
- Department of Surgery, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Liu X, Huang J, Parameswaran S, Ito T, Seubert B, Auer M, Rymaszewski A, Jia G, Owen HA, Zhao D. The SPOROCYTELESS/NOZZLE gene is involved in controlling stamen identity in Arabidopsis. Plant Physiol 2009; 151:1401-11. [PMID: 19726570 PMCID: PMC2773108 DOI: 10.1104/pp.109.145896] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Accepted: 08/28/2009] [Indexed: 05/18/2023]
Abstract
The stamen, which consists of an anther and a filament, is the male reproductive organ in a flower. The specification of stamen identity in Arabidopsis (Arabidopsis thaliana) is controlled by a combination of the B genes APETALA3 (AP3) and PISTILLATA, the C gene AGAMOUS (AG), and the E genes SEPALLATA1 (SEP1) to SEP4. The "floral organ-building" gene SPOROCYTELESS/NOZZLE (SPL/NZZ) plays a central role in regulating anther cell differentiation. However, much less is known about how "floral organ identity" and floral organ-building genes interact to control floral organ development. In this study, we report that ectopic expression of SPL/NZZ not only affects flower development in the wild-type background but also leads to the transformation of petal-like organs into stamen-like organs in flowers of ap2-1, a weak ap2 mutant allele. Moreover, our loss-of-function analysis indicates that the spl/nzz mutant enhances the phenotype of the ag weak allele ag-4. Furthermore, ectopic expression and overexpression of SPL/NZZ altered expression of AG, SEP3, and AP2 in rosette leaves and flowers, while ectopic expression of SPL/NZZ resulted in ectopic expression of AG and SEP3 in the outer whorls of flowers. Our results indicate that the SPL/NZZ gene is engaged in controlling stamen identity via interacting with genes required for stamen identity in Arabidopsis.
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