Force-dependent calcium signaling and its pathway of human neutrophils on P-selectin in flow

Abstract

P-selectin engagement of P-selectin glycoprotein ligand-1 (PSGL-1) causes circulating leukocytes to roll on and adhere to the vascular surface, and mediates intracellular calcium flux, a key but unclear event for subsequent arresting firmly at and migrating into the infection or injured tissue. Using a parallel plate flow chamber technique and intracellular calcium ion detector (Fluo-4 AM), the intracellular calcium flux of firmly adhered neutrophils on immobilized P-selectin in the absence of chemokines at various wall shear stresses was investigated here in real time by fluorescence microscopy. The results demonstrated that P-selectin engagement of PSGL-1 induced the intracellular calcium flux of firmly adhered neutrophils in flow, increasing P-selectin concentration enhanced cellular calcium signaling, and, force triggered, enhanced and quickened the cytoplasmic calcium bursting of neutrophils on immobilized P-selectin. This P-selectin-induced calcium signaling should come from intracellular calcium release rather than extracellular calcium influx, and be along the mechano-chemical signal pathway involving the cytoskeleton, moesin and Spleen tyrosine kinase (Syk). These results provide a novel insight into the mechano-chemical regulation mechanism for P-selectin-induced calcium signaling of neutrophils in flow.

A single amino acid substitution in CXCL12 confers functional selectivity at the beta-arrestin level

“…After G protein coupling, the exchange of GTP for GDP on the α subunit induces conformational changes that lead to βγ complex dissociation and signaling initiation. Both Gα i and Gβγ subunits promote phospholipases activation to trigger intracellular calcium flux [ 6 ], which can be regarded as a universal signal transducer involved in the regulation of a wide number of physiological processes, such as gene transcription, cell proliferation and migration [ 22 , 23 ]. To investigate the differences in calcium flux induction between CXCL12 and its mutant variant, we loaded Jurkat cells, endogenously expressing CXCR4, with the green fluorescent calcium indicator Fluo-4 AM and recorded the results over a time period of 250 seconds.…”

Toll-like Receptor 4 Signaling and Downstream Neutrophilic Inflammation Mediate Endotoxemia-Enhanced Blood–Labyrinth Barrier Trafficking

“…Concurrently, endothelial barriers increase the expression of leukocyte adhesion molecules such as P-SELECTIN (50) and ICAM1 (51,52) promoting leukocyte adhesion, neutrophil-mediated vascular injury, and diapedesis leading to paracellular trafficking (27,31) routes (hours later) not present under healthy physiological states (Fig. 5C) (33,50,53). Enhanced BLB trafficking at early time points is likely most reliant on increased transcellular trafficking mechanisms (pino/transcytosis, ionchannel, and specific transporters) with paracellular theoretically becoming more apparent at later time points after neutrophil-mediated vascular injury accumulation (Fig.…”

Mechanical tumor microenvironment and transduction: cytoskeleton mediates cancer cell invasion and metastasis

“…Most internal Ca 2+ signals originate from the endoplasmic reticulum (ER) through inositol triphosphate (IP 3 ) receptors and extracellular calcium influx is induced by calcium channels of the TRP family, Piezo1/2, and Cav family, for example. Some of the cellular calcium signaling is triggered by mechanical force [181]. Increased Ca 2+ concentration in the cytoplasm is regulated locally and globally for effective cytoskeletal remodeling, cell migration and cancer metastasis.…”