title: The scaffolding function of the RLTPR protein explains its essential role for CD28 co-stimulation in mouse and human T cells.
abstract: The RLTPR cytosolic protein, also known as CARMIL2, is essential for CD28 co-stimulation in mice, but its importance in human T cells and mode of action remain elusive. Here, using affinity purification followed by mass spectrometry analysis, we showed that RLTPR acts as a scaffold, bridging CD28 to the CARD11/CARMA1 cytosolic adaptor and to the NF-κB signaling pathway, and identified proteins not found before within the CD28 signaling pathway. We further demonstrated that RLTPR is essential for CD28 co-stimulation in human T cells and that its noncanonical pleckstrin-homology domain, leucine-rich repeat domain, and proline-rich region were mandatory for that task. Although RLTPR is thought to function as an actin-uncapping protein, this property was dispensable for CD28 co-stimulation in both mouse and human. Our findings suggest that the scaffolding role of RLTPR predominates during CD28 co-stimulation and underpins the similar function of RLTPR in human and mouse T cells. Along that line, the lack of functional RLTPR molecules impeded the differentiation toward Th1 and Th17 fates of both human and mouse CD4+T cells. RLTPR was also expressed in both human and mouse B cells. In the mouse, RLTPR did not play, however, any detectable role in BCR-mediated signaling and T cell-independent B cell responses.
authors.affiliation: Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, INSERM, CNRS, 13288 Marseille, France.
authors.forename: Romain
authors.identifier: 0000-0001-7554-0552
authors.initials: R
authors.lastname: Roncagalli
authors.affiliation: Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, INSERM, CNRS, 13288 Marseille, France.
authors.forename: Margot
authors.initials: M
authors.lastname: Cucchetti
authors.affiliation: Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, INSERM, CNRS, 13288 Marseille, France.
authors.forename: Nicolas
authors.identifier: 0000-0003-0924-9622
authors.initials: N
authors.lastname: Jarmuzynski
authors.affiliation: Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, INSERM, CNRS, 13288 Marseille, France.
authors.forename: Claude
authors.initials: C
authors.lastname: Grégoire
authors.affiliation: Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, INSERM, CNRS, 13288 Marseille, France.
authors.forename: Elise
authors.identifier: 0000-0003-1425-6560
authors.initials: E
authors.lastname: Bergot
authors.affiliation: CRCM, Marseille Protéomique, Institut Paoli-Calmettes, Aix Marseille Université, INSERM, CNRS, 13009 Marseille, France.
authors.forename: Stéphane
authors.identifier: 0000-0002-9409-2588
authors.initials: S
authors.lastname: Audebert
authors.affiliation: CRCM, Marseille Protéomique, Institut Paoli-Calmettes, Aix Marseille Université, INSERM, CNRS, 13009 Marseille, France.
authors.forename: Emilie
authors.initials: E
authors.lastname: Baudelet
authors.affiliation: Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, INSERM, CNRS, 13288 Marseille, France.
authors.forename: Marisa Goncalves
authors.initials: MG
authors.lastname: Menoita
authors.affiliation: Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, INSERM, CNRS, 13288 Marseille, France.
authors.forename: Anais
authors.identifier: 0000-0002-8902-8696
authors.initials: A
authors.lastname: Joachim
authors.affiliation: Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, INSERM, CNRS, 13288 Marseille, France.
authors.forename: Stéphane
authors.identifier: 0000-0001-8253-103X
authors.initials: S
authors.lastname: Durand
authors.affiliation: Exbio Praha, Vestec, Czech Republic.
authors.forename: Miloslav
authors.initials: M
authors.lastname: Suchanek
authors.affiliation: Centre d'Immunophénomique, Aix Marseille Université, INSERM, CNRS, 13288 Marseille, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Fiore
authors.affiliation: Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, INSERM, CNRS, 13288 Marseille, France.|School of Laboratory Medicine, Xinxiang Medical University, Xinxiang 453003, China.
authors.forename: Lichen
authors.identifier: 0000-0002-5000-470X
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, INSERM, CNRS, 13288 Marseille, France.|School of Laboratory Medicine, Xinxiang Medical University, Xinxiang 453003, China.
authors.forename: Yinming
authors.initials: Y
authors.lastname: Liang
authors.affiliation: CRCM, Marseille Protéomique, Institut Paoli-Calmettes, Aix Marseille Université, INSERM, CNRS, 13009 Marseille, France.
authors.forename: Luc
authors.initials: L
authors.lastname: Camoin
authors.affiliation: Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, INSERM, CNRS, 13288 Marseille, France bernardm@ciml.univ-mrs.fr malissen@ciml.univ-mrs.fr.|Centre d'Immunophénomique, Aix Marseille Université, INSERM, CNRS, 13288 Marseille, France.
authors.forename: Marie
authors.identifier: 0000-0003-2331-1445
authors.initials: M
authors.lastname: Malissen
authors.affiliation: Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université, INSERM, CNRS, 13288 Marseille, France bernardm@ciml.univ-mrs.fr malissen@ciml.univ-mrs.fr.|Centre d'Immunophénomique, Aix Marseille Université, INSERM, CNRS, 13288 Marseille, France.
authors.forename: Bernard
authors.identifier: 0000-0003-1340-9342
authors.initials: B
authors.lastname: Malissen
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D018106:CD28 Antigens / Q000378:metabolism*; D003713:Dendritic Cells / Q000378:metabolism; D004705:Endocytosis; D018390:Gene Targeting; D057809:HEK293 Cells; D006801:Humans; D019169:Jurkat Cells; D007694:Killer Cells, Natural / Q000378:metabolism; D008214:Lymphocytes / Q000378:metabolism; D051379:Mice; D008840:Microfilament Proteins / Q000737:chemistry / Q000378:metabolism*; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D022423:Myeloid Cells / Q000378:metabolism; D000072417:Protein Domains; D025941:Protein Interaction Mapping; D055503:Protein Multimerization; D040901:Proteomics; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000378:metabolism*; D050378:T-Lymphocytes, Regulatory / Q000378:metabolism; D060168:Thymocytes / Q000378:metabolism
chemical_list: C547525:CARMIL1 protein, human; D018106:CD28 Antigens; C504800:Carmil1 protein, mouse; D008840:Microfilament Proteins