biostudies-literatureRoncagalli REuropean Research CouncilAgence Nationale de la RechercheInstitut National de la Santé et de la Recherche MédicaleCentre National de la Recherche ScientifiqueAxa Research Fund2437-2457https://www.ebi.ac.uk/biostudies/studies/S-EPMC5068240biostudies-literatureUnknown213(11)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 The Journal of experimental medicineThe scaffolding function of the RLTPR protein explains its essential role for CD28 co-stimulation in mouse and human T cells.PMC5068240322465Jarmuzynski NRoncagalli RLiang YJoachim ABergot ECamoin LGregoire CZhang LMalissen BSuchanek MDurand SMalissen MCucchetti MFiore FBaudelet EAudebert SMenoita MGfalseThe scaffolding function of the RLTPR protein explains its essential role for CD28 co-stimulation in mouse and human T cells.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 2016-01-01T00:00:00Z2016 Oct2026-04-30T01:10:16.219Z2019-03-27T02:26:57ZS-EPMC50682402764734810.1084/jem.20160579