Liposomes as a Putative Tool to Investigate NAADP Signaling in Vasculogenesis

Abstract

Nicotinic acid adenine dinucleotide phosphate (NAADP) is the newest discovered intracellular second messengers, which is able to release Ca stored within endolysosomal (EL) vesicles. NAADP-induced Ca signals mediate a growing number of cellular functions, ranging from proliferation to muscle contraction and differentiation. Recently, NAADP has recently been shown to regulate angiogenesis by promoting endothelial cell growth. It is, however, still unknown whether NAADP stimulates proliferation also in endothelial progenitor cells, which are mobilized in circulation after an ischemic insult to induce tissue revascularization. Herein, we described a novel approach to prepare NAADP-containing liposomes, which are highly cell membrane permeable and are therefore amenable for stimulating cell activity. Accordingly, NAADP-containing liposomes evoked an increase in intracellular Ca concentration, which was inhibited by NED-19, a selective inhibitor of NAADP-induced Ca release. Furthermore, NAADP-containing liposomes promoted EPC proliferation, a process which was inhibited by NED-19 and BAPTA, a membrane permeable intracellular Ca buffer. Therefore, NAADP-containing liposomes stand out as a promising tool to promote revascularization of hypoxic/ischemic tissues by favoring EPC proliferation. J. Cell. Biochem. 118: 3722-3729, 2017. © 2017 Wiley Periodicals, Inc.

VEGF-induced intracellular Ca2+ oscillations are down-regulated and do not stimulate angiogenesis in breast cancer-derived endothelial colony forming cells

“…Accordingly, nicotinic acid adenine dinucleotide phosphate (NAADP) has been recently shown to underpin VEGF-induced endothelial Ca 2+ signals and neo-angiogenesis in melanoma [ 67 ]. An NAADP-sensitive lysosomal Ca 2+ store is also present in N-ECFCs [ 30 , 68 ], although it is seemingly down-regulated in BC-ECFCs (unpublished observations from our group).…”

TRPC3‐mediated Ca2+ signals as a promising strategy to boost therapeutic angiogenesis in failing hearts: The role of autologous endothelial colony forming cells

“…Likewise, PB‐ECFCs do not possess RyRs (Zuccolo, Dragoni, et al, ), which are also present in mature endothelial cells (Long, Cook, Wu, & Mitchell, ; Zhang et al, ). Finally, PB‐ECFCs display a remarkable acidic Ca 2+ store that can be liberated by NAADP‐gated TPC1 channels (Di Nezza et al, ; Zuccolo, Dragoni, et al, ). In terms of pro‐angiogenic Ca 2+ signals, TRPV4, albeit functionally expressed, exerts only a weak proliferative action on PB‐ECFCs (Dragoni, Guerra, et al, ), in marked contrast with its established role in arterial remodeling (Troidl et al, , ).…”

“…While the role played by InsP 3 Rs has been clearly established, it is still unknown whether NAADP‐gated TPC1 contributes to the onset of the Ca 2+ response to VEGF, as recently observed in HUVECs (Favia et al, , ). It is, however, intriguing that intracellularly delivered NAADP stimulates ECFC proliferation in a TPC‐dependent manner (Di Nezza et al, ). Parallel work from Prof. Beech's group confirmed that the genetic silencing of Stim1 and Orai1 prevent VEGF‐evoked Ca 2+ inflow in PB‐ECFCs, whereas VEGF promotes Stim1 relocation into sub‐membranal puncta (Li et al, ).…”

Endothelial Ca2+ Signaling and the Resistance to Anticancer Treatments: Partners in Crime

“…NAADP-induced EL Ca 2+ release is, in turn, amplified by juxtaposed ER-embedded InsP 3 Rs and RyRs through the CICR process, thereby initiating a regenerative Ca 2+ wave [ 196 , 200 , 201 ]. NAADP-gated TPC2 channels are also expressed in vascular ECs [ 202 , 203 ], whereas N- ECFCs display larger amounts of TPC1 [ 86 , 204 ]. A recent study demonstrated that NAADP-induced Ca 2+ signals promoted tumor vascularization and metastasis in murine models xenografted with B16 melanoma cells [ 205 ].…”