NAADP-mediated calcium release promotes angiopoietin 2 secretion by regulating Rab46-dependent Weibel-Palade body trafficking
Year: 2025
Type: article
Abstract: • Histamine evokes an NAADP-sensitive calcium signal that is necessary for the detachment of angiopoietin2-containing Weibel-Palade bodies (WPBs) from the MTOC upon histamine signalling in human aortic endothelial cells. • Ned-19 mediated inhibition of NAADP channel proteins TPC1/2 promotes histamine-evoked clustering of WPBs at the MTOC and inhibits secretion of angiopoietin2. • TPC2-A1-N enhances the histamine-evoked calcium signal and enables WPB release from the MTOC and promotes angiopoietin2 secretion. Angiopoietin2 (Ang2), a regulator of angiogenesis, is stored with other pro-inflammatory and pro-thrombotic mediators, in endothelial-specific vesicles called Weibel-Palade bodies (WPBs). Acute stimulation of endothelial cells with histamine, delays Ang2 secretion by activating Rab46-specific trafficking of Ang2-containing WPBs to the microtubule organising centre (MTOC), where they persist until Ca²⁺ binds to the EF-hand of Rab46, enabling detachment. Here, using Ca²⁺ imaging and high-resolution light microscopy, we pharmacologically investigated the contribution of endolysosomal two-pore channel proteins (TPC) to the Ca²⁺ signal necessary for WPB detachment and Ang2 secretion. We show an increase in the histamine-evoked clustering of Rab46 (and thus WPBs) at the MTOC in the presence of TPC inhibitors Ned-19 and tetrandrine, and a decrease in the presence of a TPC2 agonist, TPC2-A1-N. Histamine-evoked secretion of Ang2 was decreased by pharmacological inhibition of TPC channels but potentiated in the presence of TPC2-A1-N. These data suggest that histamine-mediated Ca²⁺ release via TPC2 channels is necessary for the Rab46-dependent detachment of Ang2-positive WPBs from the MTOC and thus Ang2 secretion. Ca²⁺ binding to the EF-hand of Rab46 in endothelial cells has previously been reported but the molecular mechanisms and functional relevance are unclear. Here, the authors show that Ca²⁺ released from TPC channels regulates the detachment of Rab46-positive WPBs from the MTOC, which thereby promotes secretion of Ang2. The role of NAADP-sensitive Ca²⁺ channels in Rab46-dependent trafficking of Ang2-positive Weibel-Palade bodies. Created using https:// BioRender.com
Source: Cell Calcium
Authors: Ryan D. Murray, Melissa Rose, Katarina T. Miteva, David J. Beech, Lynn McKeown
Institutions: University of Leeds, University of Edinburgh
Language: English
Subfield: Physiology
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,950
OpenAlex ID: W4413970647