Organelles Containing Inositol Trisphosphate Receptor Type 2 in Adrenal Medullary Cells

Abstract

Abstract:To identify which organelles contained inositol trisphosphate (InsP 3 ) receptor type 2 (InsP 3 R2) in adrenal medullary (AM) cells, immunocytochemical and biochemical studies were performed on AM cells of several species. InsP 3 R2-like immunoreactive materials produced by two different anti-InsP 3 R2 antibodies (Abs) (Chemicon and Sigma) were distributed in rat AM cells in agreement with BODIPY-FL-InsP 3 binding sites. For two other Abs (KM1083 and Santa Cruz), some of the antiInsP 3 R2 immunoreactive materials were stained with an antidopamine-β-hydroxylase Ab, but not by BODIPY-FL-InsP 3 . BO-DIPY-FL-thapsigargin binding sites were consistent with a distribution of the endoplasmic reticulum (ER) identified by an anticalnexin Ab, and a prior application of thapsigargin significantly eliminated BODIPY-FL-thapsigargin bindings, suggesting that BODIPY-FL-thapsigargin bindings were mediated by thapsigargin, but not the fluorescence molecule. The anti-InsP 3 R2 Ab that produced stainings consistent with BODIPY-FL-InsP 3 bindings recognized a protein with about 250 kDa. A fractional analysis of bovine adrenal medullae revealed that the 250 kDa InsP 3 R2 was detected in a crude membrane fraction, but not in a secretory granule fraction. The results suggest that the InsP 3 R2 was present in the ER, but not in secretory granules in AM cells.

Ca2+ pathway involved in the refilling of store sites in rat adrenal medullary cells

“…Since the punctate distribution of TRPC1 channel-like IR resembles that of the endoplasmic reticulum (ER), AM cells were double stained with the anti-TRPC1 Ab and BODIPY-FL-thapsigargin, a chemical that selectively binds to the ER (9,25). Figure 7D clearly shows that the majority of TRPC1 channel-like IR coincided with BODPY-FL thapsigargin binding (n ϭ 12), suggesting that TRPC1 channels are present in the ER in AM cells.…”

Calcium dynamics in bovine adrenal medulla chromaffin cell secretory granules

“…, 1996, 2006). However, results from other authors indicate that in chromaffin cells, InsP 3 receptors are present in the ER but not in the secretory granules (Endo et al. , 2006).…”

Ca2+ Dynamics in the Secretory Vesicles of Neurosecretory PC12 and INS1 Cells

“…The reasons for the discrepancy may rely in the different properties of the different kinds of secretory granules, and perhaps also in the different methodologies for measuring granular [Ca 2? ], either in a whole population of heterogeneous granules or in defined when stimulated with InsP 3 , suggesting the presence of InsP 3 receptors in the vesicles. In fact, the presence of InsP 3 R in the membrane of chromaffin cell secretory granules has been a matter of debate for a long time (Yoo and Albanesi 1990;Pouli et al 1998;Huh et al 2005;Endo et al 2006;Yoo 2010). Regarding ryanodine receptors, we show that caffeine releases Ca 2?…”

“…Some authors have reported that chromaffin granules (Yoo and Albanesi 1990;Huh et al 2005;Yoo 2010), mast cell secretory granules (Quesada et al 2001(Quesada et al , 2003 and pancreatic acinar cells secretory granules (Gerasimenko et al 1996(Gerasimenko et al , 2006 possess functional inositol 1,4,5-trisphosphate (InsP 3 ) receptors. However, work from other authors suggests that InsP 3 receptors are present only in the endoplasmic reticulum but not in the secretory granules of chromaffin cells (Endo et al 2006), or that cell stimulation does not produce any Ca 2? release from the granules in PC12 cells (Pouli et al 1998).…”