Hormonal Control of ADP-ribosyl Cyclase Activity in Pancreatic Acinar Cells from Rats

Abstract

Cyclic ADP-ribose, a metabolite of NAD ؉ evokes Ca 2؉ release from intracellular stores in different cells. We have determined the activity of cADPr-producing enzymes (ADP-ribosyl cyclases) in different cellular fractions prepared from isolated pancreatic acinar cells by measuring the conversion of the ␤-NAD ؉ analogs 1,N 6 -etheno-NAD and nicotinamide guanine dinucleotide to the fluorescent products 1,N 6 -etheno-cADPr and cyclic GDP-ribose, respectively. Substrate/product analyses were carried out by reverse-phase high pressure liquid chromatography. In all subcellular fractions examined (cytosol, mitochondria, plasma, and intracellular membranes), ADP-ribosyl cyclase activity was detected except in zymogen granular membranes. Western blot analysis and immunoprecipitation experiments revealed the presence of the ADP-ribosyl cyclase CD38 in both plasma membranes and mitochondria but not in the cytosol. Hormonal stimulation of intact acinar cells for 1 min with acetylcholine (ACh), cholecystokinin (CCK), or a membrane-permeant analog of cGMP increased ADP-ribosyl cyclase activity in the cytosol by 1.8-, 1.6-, and 1.9-fold, respectively, as compared with the control but had no effect in any other fraction. Both ACh and CCK also increased accumulation of cGMP in the cells by about 2-fold. Bombesin had no significant effect on either ADP-ribosyl cyclase activity or cGMP accumulation within this short period of stimulation. We conclude that at least two types of ADP-ribosyl cyclases are present in pancreatic acinar cells: membrane-bound CD38 and a cytosolic enzyme different from CD38. Stimulation of pancreatic acinar cells with CCK or ACh results in exclusive activation of the cytosolic ADP-ribosyl cyclase activity, most likely mediated by cGMP.Hormonal stimulation of pancreatic acinar cells stimulates production of inositol 1,4,5-trisphosphate (IP 3 ) 1 with a consequent release of Ca 2ϩ from intracellular Ca 2ϩ stores (1). This leads to an increase in cytosolic [Ca 2ϩ ], which propagates from the luminal to the basolateral cell pole as a Ca 2ϩ wave (2-4). In addition to IP 3 -induced Ca 2ϩ release, also Ca 2ϩ -induced Ca 2ϩ release exists in pancreatic acinar cells (2, 5, 6). The Ca 2ϩ wave velocity (7) depends on the secretagogue that is used to maximally stimulate the cell (3, 7, 8), indicating that different extracellular stimuli may utilize a different set of second messengers.Cyclic adenosine diphosphoribose (cADPr) leads to Ca 2ϩ release from intracellular stores of sea urchin eggs (9) and from different mammalian cell types (reviewed in Ref. 10) including cells from the exocrine (5) and endocrine (11) pancreas. In pancreatic acinar cells, cADPr applied to the cell via a patch pipette induced Ca 2ϩ oscillations (5) and Ca 2ϩ release from intracellular stores when applied to permeabilized cells (12,13).Production of cADPr, activated by extracellular signals, has been shown only in a limited number of cell types, e.g. in pancreatic islets (11), smooth muscle cells (14), cardiac myocytes (15), cortical astrocy...

Cyclic ADP-ribose and NAADP: fraternal twin messengers for calcium signaling

“…However, cGMP-independent cADPR synthesis had also been found in the eggs [130]. In mammalian cells, both cGMP- [110,[131][132][133] and cAMP-dependent [134][135][136][137] cADPR-synthesis have been reported. Likewise, in lymphokine-activated killer cells, NAADP synthesis is stimulated by both cAMP and cGMP [110].…”

Oxytocin-induced elevation of ADP-ribosyl cyclase activity, cyclic ADP-riboseor Ca2+ concentrations is involved in autoregulation of oxytocin secretionin the hypothalamus and posterior pituitary in male mice

“…Intracellular cADPR concentrations are known to be regulated in many different ways: in one such mechanism, ADP-ribosyl cyclase or CD38 seems to be coupled directly with neurotransmitter or hormone receptors such as muscarinic acetylcholine or metabotropic glutamate receptors via different G proteins on the membrane surface (Higashida et al, 1997(Higashida et al, , 1999(Higashida et al, , 2007; or phosphorylation downstream of the G-protein-coupled receptor signaling pathway (Boittin et al, 2003;Sternfeld et al, 2003). Specifically, the activation of ADP-ribosyl cyclase or CD38 by cyclic GMP-or cyclic AMP-dependent protein kinases has been reported in Aplysia californica (Graeff et al, 1998), LAK cells (Rah et al, 2005) and artery smooth muscle cells (Boittin et al, 2003).…”

Ryanodine receptor subtype 2 encodes Ca2+ oscillations activated by acetylcholine via the M2 muscarinic receptor/cADP-ribose signalling pathway in duodenum myocytes

“…ADP-ribosyl cyclase activity and cADPR-induced Ca 2+ oscillations As previously reported in biochemical studies on subcellular fractions (Graeff et al, 1994;Sternfeld et al, 2003), we used the cyclization of NGD+ into cGDPR (a fluorescent compound) to evaluate the ADP-ribosyl cyclase activity. In single permeabilized duodenum myocytes, application of 1 µM ACh for 30 seconds induced an increase in fluorescence detected at 420 nm (Fig.…”

“…To confirm the involvement of cADPR, ADP-ribosyl cyclase activity was inhibited in permeabilized cells using ZnCl 2 (de Toledo et al, 2000), high concentrations of NGD+ and an anti-CD38 antibody (Sternfeld et al, 2003). Application of 2 mM ZnCl 2 decreased significantly the amplitude of ACh-induced Ca 2+ responses and suppressed Ca 2+ oscillations (Fig.…”