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Martinelli M, Aguilar G, Lee DS, Kromer A, Nguyen N, Wilkins BJ, Akimova T, Beier UH, Ghanem LR. The poly(C)-binding protein Pcbp2 is essential for CD4 + T cell activation and proliferation. iScience 2022; 26:105860. [PMID: 36632062 PMCID: PMC9826892 DOI: 10.1016/j.isci.2022.105860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 11/16/2022] [Accepted: 12/18/2022] [Indexed: 12/24/2022] Open
Abstract
The RNA-binding protein Pcbp2 is widely expressed in the innate and adaptive immune systems and is essential for mouse development. To determine whether Pcbp2 is required for CD4+ T cell development and function, we derived mice with conditional Pcbp2 deletion in CD4+ T cells and assessed their overall phenotype and proliferative responses to activating stimuli. We found that Pcbp2 is essential for T conventional cell (Tconv) proliferation, working through regulation of co-stimulatory signaling. Pcbp2 deficiency in the CD4+ lineage did not impact Treg abundance in vivo or function in vitro. In addition, our data demonstrate a clear association between Pcbp2 control of Runx1 exon 6 splicing in CD4+ T cells and a specific role for Pcbp2 in the maintenance of peripheral CD4+ lymphocyte population size. Last, we show that Pcbp2 function is required for optimal in vivo Tconv cell activation in a T cell adoptive transfer colitis model system.
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Affiliation(s)
- Massimo Martinelli
- Division of Gastroenterology, Hepatology and Nutrition Division, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA,Department of Translational Medical Science, Section of Pediatrics, University of Naples “Federico II”, Naples 80131, Italy
| | - Gabrielle Aguilar
- Division of Gastroenterology, Hepatology and Nutrition Division, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - David S.M. Lee
- Department of Genetics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA,Institute for Biomedical Informatics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Andrew Kromer
- Division of Gastroenterology, Hepatology and Nutrition Division, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Nhu Nguyen
- Division of Gastroenterology, Hepatology and Nutrition Division, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Benjamin J. Wilkins
- Division of Anatomic Pathology, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA,Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Tatiana Akimova
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ulf H. Beier
- Division of Nephrology, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Louis R. Ghanem
- Division of Gastroenterology, Hepatology and Nutrition Division, The Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA,Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA,Corresponding author
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Yanatori I, Richardson DR, Toyokuni S, Kishi F. The iron chaperone poly(rC)-binding protein 2 forms a metabolon with the heme oxygenase 1/cytochrome P450 reductase complex for heme catabolism and iron transfer. J Biol Chem 2017; 292:13205-13229. [PMID: 28655775 DOI: 10.1074/jbc.m117.776021] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 06/26/2017] [Indexed: 11/06/2022] Open
Abstract
Mammals incorporate a major proportion of absorbed iron as heme, which is catabolized by the heme oxygenase 1 (HO1)-NADPH-cytochrome P450 reductase (CPR) complex into biliverdin, carbon monoxide, and ferrous iron. Moreover, intestinal iron is incorporated as ferrous iron, which is transported via the iron importer, divalent metal transporter 1 (DMT1). Recently, we demonstrated that the iron chaperone poly(rC)-binding protein 2 (PCBP2) can directly receive ferrous iron from DMT1 or transfer iron to the iron exporter, ferroportin 1. To promote intracellular iron flux, an iron chaperone may be essential for receiving iron generated by heme catabolism, but this hypothesis is untested so far. Herein, we demonstrate that HO1 binds to PCBP2, but not to other PCBP family members, namely PCBP1, PCBP3, or PCBP4. Interestingly, HO1 formed a complex with either CPR or PCBP2, and it was demonstrated that PCBP2 competes with CPR for HO1 binding. Using PCBP2-deletion mutants, we demonstrated that the PCBP2 K homology 3 domain is important for the HO1/PCBP2 interaction. In heme-loaded cells, heme prompted HO1-CPR complex formation and decreased the HO1/PCBP2 interaction. Furthermore, in vitro reconstitution experiments with purified recombinant proteins indicated that HO1 could bind to PCBP2 in the presence of heme, whereas loading of PCBP2 with ferrous iron caused PCBP2 to lose its affinity for HO1. These results indicate that ferrous iron released from heme can be bound by PCBP2 and suggest a model for an integrated heme catabolism and iron transport metabolon.
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Affiliation(s)
- Izumi Yanatori
- From the Department of Molecular Genetics, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama 701-0192, Japan
| | - Des R Richardson
- the Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia, and
| | - Shinya Toyokuni
- the Molecular Pharmacology and Pathology Program, Department of Pathology, University of Sydney, Sydney, New South Wales 2006, Australia, and.,the Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | - Fumio Kishi
- From the Department of Molecular Genetics, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama 701-0192, Japan,
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