Leukotriene D4 binding and signal transduction in rat glomerular mesangial cells

Abstract

We examined the characteristics of [3H]leukotriene D4 (LTD4) binding to mesangial cells in culture. Binding is stereoselective, specific, saturable, and rapidly reversible. Two binding sites are recognized with dissociation constants and binding site densities at equilibrium of 2.2 and 16.8 nM and 1.1 x 10(4) and 3 x 10(4) binding sites per cell. LTD4, LTE4, (5R,6S)LTD4, LTB4, and the LTD4-receptor antagonist, SKF 104353, competitively inhibit radioligand binding in the following rank order of potency: LTD4 greater than LTE4 = SKF 104353 greater than (5R,6S)LTD4 greater than LTB4. LTD4 also induces time- and concentration-dependent phosphoinositide hydrolysis in mesangial cells. Formation of inositol 1,4,5-trisphosphate (IP3) is maximal at 5 s, followed by a time-dependent increase in inositol monophosphate generation, and inhibited by 100-fold excess concentration of SKF 104353. Addition of LTD4 to mesangial cells is associated with an increase in intracellular pH and dose-dependent stimulation of [3H]thymidine incorporation and mitogenesis. Thus rat mesangial cells possess specific binding sites for LTD4, the activation of which stimulates IP3 formation and induces cellular alkalinization and mitogenic responses. These studies provide insight into the cellular basis for LTD4-mesangial cell interactions, which are of potential pathophysiological relevance during acute glomerular inflammatory injury.

Leukotriene D4-induced mobilization of intracellular Ca2+ in epithelial cells is critically dependent on activation of the small GTP-binding protein Rho

“…) and E % , the constituents of the slow-reacting substance of anaphylaxis, are extremely potent and have a large number of physiological effects [1,3]. These effects are generally agreed to be mediated via the interaction of the leukotrienes with specific plasma membrane receptors on the affected cells [4][5][6][7].…”

Deficiency of 5-Lipoxygenase Accelerates Renal Allograft Rejection in Mice

“…They are potent vasoconstrictors (21)(22)(23)(24) and can cause contraction of endothelial cells, resulting in increased permeability of postcapillary venules (13,14,16). Cysteinyl-LTs also stimulate contraction of glomerular mesangial cells (25)(26)(27) and may alter production of other inflammatory mediators (28,29). Based on their known biologic properties, enhanced synthesis of LTs during transplant rejection could therefore promote renal inflammation and injury through a variety of direct and indirect mechanisms.…”