GSBS Student Publications

Title

Calcium signalling during chemotaxis

GSBS Program

Biochemistry & Molecular Pharmacology

UMMS Affiliation

Graduate School of Biomedical Sciences; Department of Physiology

Date

1-1-1995

Document Type

Article

Medical Subject Headings

Animals; Calcium; Chemotaxis, Leukocyte; Eosinophils; Salamandridae; *Signal Transduction

Disciplines

Life Sciences | Medicine and Health Sciences

Abstract

The role of Ca2+ in chemotaxis of eosinophils from the newt Taricha granulosa was investigated using fluorescent indicators and digital imaging microscopy. In response to serum chemoattractant, cytoplasmic Ca2+ concentration ([Ca2+]i) rises prior to polarization. In polarized locomoting cells [Ca2+]i gradients (tail-high-front-low) are always seen, and when cells turn [Ca2+]i rises transiently and falls fastest and furthest in the new direction of cell motion. These Ca2+ signals, which are required for polarization and locomotion, arise from Ca2+ derived from internal stores released in response to inositol 1,4,5-trisphosphate (InsP3) (because microinjected heparin fully blocks them). 1,2-Diacyl-sn-glycerol (DAG), which is co-produced with InsP3, has an inhibitory effect on Ca2+ signals, an effect apparently mediated by protein kinase C. Studies with caged InsP3 reveal that InsP3-responsive stores appear to be concentrated in the nuclear and microtubule-organizing centre regions and that InsP3 moves so rapidly within the cell that it is effectively a global secondary messenger. Thus, stable [Ca2+] gradients observed during unidirectional migration appear to result from the concentration of InsP3-responsive Ca2+ stores in the rear of the cell. By contrast, we propose that reorientation of the [Ca2+] gradient prior to a change in direction of motion results from the joint actions of InsP3 and DAG, with InsP3 acting as a global secondary messenger stimulating Ca2+ release and DAG, through protein kinase C, acting as a spatially restricted secondary messenger inhibiting [Ca2+] increases locally near the site of chemotactic stimulation.

Rights and Permissions

Citation: Ciba Found Symp. 1995;188:121-35; discussion 136-40.

Related Resources

Link to article in PubMed

Journal Title

Ciba Foundation symposium

PubMed ID

7587614