analysis-shear-flow-induced-migration-murine-marginal-zone-b-cells

Analysis of Shear Flow-induced Migration of Murine Marginal Zone B Cells In Vitro

Marginal zone B cells (MZBs) are a population of B cells that reside in the mouse splenic marginal zones that envelop follicles. To reach the follicles, ...

OVGU University of Magdeburg

The outcome of T cell activation is determined by mechanisms that balance Ca influx and clearance. Here we report that murine CD4 T cells lacking Neuroplastin (Nptn ), an immunoglobulin superfamily protein, display elevated cytosolic Ca and impaired post-stimulation Ca clearance, along with increased nuclear levels of NFAT transcription factor and enhanced T cell receptor-induced cytokine production. On the molecular level, we identified plasma membrane Ca ATPases (PMCAs) as the main interaction partners of Neuroplastin. PMCA levels were reduced by over 70% in Nptn  T cells, suggesting an explanation for altered Ca handling. Supporting this, Ca extrusion was impaired while Ca levels in internal stores were increased. T cells heterozygous for PMCA1 mimicked the phenotype of Nptn  T cells. Consistent with sustained Ca levels, differentiation of Nptn  T helper cells was biased towards the Th1 versus Th2 subset. Our study thus establishes Neuroplastin-PMCA modules as important regulators of T cell activation.

A complex of Neuroplastin and Plasma Membrane Ca ATPase controls T cell activation.

Splenic marginal zone B cells (MZB) shuttle between the blood-filled marginal zone for antigen collection and the follicle for antigen delivery. However, it is unclear how MZBs migrate directionally from the marginal zone to the follicle. Here, we show that murine MZBs migrate up shear flow via the LFA-1 (αLβ2) integrin ligand ICAM-1, but adhere or migrate down the flow via the VLA-4 integrin (α4β1) ligand VCAM-1. MZBs lacking Arhgef6 (Pak-interacting exchange factor (αPIX)) or functional LFA-1 are impaired in shuttling due to mislocalization toward the VCAM-1-rich red pulp. Sphingosine-1-phosphate (S1P) signaling through the S1PR3 receptor inhibits MZB migration up the flow, and deletion of S1pr3 in Arhgef6  mice rescues mislocalized MZBs. These findings establish shear flow as a directional cue for MZB migration to the follicle, and define S1PR3 and VCAM-1 as counteracting forces that inhibit this migration.

Article	Year
A complex of Neuroplastin and Plasma Membrane Ca ATPase controls T cell activation. Scientific reports\| PubMed ID: 28827723	2017
The opposing forces of shear flow and sphingosine-1-phosphate control marginal zone B cell shuttling. Nature communications\| PubMed ID: 29273735	2017

Klaus-Dieter Fischer

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