Zoledronate and clodronate inhibited RBL-2H3 cells degranulation without disturbing Rab27a-Doc2a interaction

Abstract

Zoledronate ability to inhibit protein prenylation marked the possibility to prevent degranulation process. Here we investigate the effect of zoledronate on RBL-2H3 cells degranulation and elucidate exocytosis proteins affected with comparison to clodronate. Histamine release on RBL-2H3 cells after zoledronate or clodronate administration was measured using HPLC-fluorometry. DNP-BSA, ionomycin, or thapsigargin are used as secretagogues. Calcium (Ca2+) influx observation was performed using Fura-2 A/M. In situ proximity ligation assay (PLA) is used to investigate Rab27a-Doc2a interaction after BPs treatment. Granule distribution was observed with FFN206 staining. Zoledronate prevent degranulation in DNP-BSA-activated cells, with the highest inhibition ～76% at 100 microM. Much of this ability is loss when the activation was performed by ionomycin or thapsigargin. Contrastly, clodronate inhibited in relatively equal level in all secretagogues groups with the maximum inhibition of 20-40% at 100 microM. The drugs activity is not affected the Ca2+ influx. Rab27a-Doc2a interaction is unchanged after zoledronate and clodronate treatment. Granules were remain inside the cell after secretagogue treatment in zoledronate and clodronate group. Inhibition of degranulation by zoledronate is not intervent the late process in degranulation arranged by Rab27a-Doc2a. Zoledronate could possibly effecting the early stage of degranulation cascade triggered by antigen that involving IgE receptor.