Inhibition of NAADP signalling on reperfusion protects the heart by preventing lethal calcium oscillations via two-pore channel 1 and opening of the mitochondrial permeability transition pore

Aims In the heart, a period of ischaemia followed by reperfusion evokes powerful cytosolic Ca2+ oscillations that can cause lethal cell injury. These signals represent attractive cardioprotective targets, but the underlying mechanisms of genesis are ill-defined. Here, we investigated the role of the second messenger nicotinic acid adenine dinucleotide phosphate (NAADP), which is known in several cell types to induce Ca2+ oscillations that initiate from acidic stores such as lysosomes, likely via two-pore channels (TPCs, TPC1 and 2). Methods and results An NAADP antagonist called Ned-K was developed by rational design based on a previously existing scaffold. Ned-K suppressed Ca2+ oscillations and dramatically protected cardiomyocytes from cell death in vitro after ischaemia and reoxygenation, preventing opening of the mitochondrial permeability transition pore. Ned-K profoundly decreased infarct size in mice in vivo. Transgenic mice lacking the endo-lysosomal TPC1 were also protected from injury. Conclusion NAADP signalling plays a major role in reperfusion-induced cell death and represents a potent pathway for protection against reperfusion injury

Second messenger analogues highlight unexpected substrate sensitivity of CD38: total synthesis of the hybrid “L-cyclic inosine 5'-diphosphate ribose”

The multifunctional, transmembrane glycoprotein human CD38 catalyses the synthesis of three key Ca2+ - mobilising messengers, including cyclic adenosine 5-diphosphate ribose (cADPR), and CD38 knockout studies have revealed the relevance of the related signalling pathways to disease. To generate inhibitors of CD38 by total synthesis, analogues based on the cyclic inosine 5-diphosphate ribose (cIDPR) template were synthesised. In the first example of a sugar hybrid cIDPR analogue, “L-cIDPR”, the natural “northern” N1-linked D-ribose of cADPR was replaced by L-ribose. L-cIDPR is surprisingly still hydrolysed by CD38, whereas 8-Br-L-cIDPR is not cleaved, even at high enzyme concentrations. Thus, the inhibitory activity of L-cIDPR analogues appears to depend upon substitution of the base at C-8; 8- Br-L-cIDPR and 8-NH2-L-cIDPR inhibit CD38-mediated cADPR hydrolysis (IC50 7 M and 21 µM respectively) with 8-Br-L-cIDPR over 20-fold more potent than 8-Br-cIDPR. In contrast, L-cIDPR displays a comparative 75-fold reduction in activity, but is only ca 2-fold less potent than cIDPR itself. Molecular modelling was used to explore the interaction of the CD38 catalytic residue Glu-226 with the “northern” ribose. We propose that Glu226 still acts as the catalytic residue even for an L-sugar substrate. 8-Br-L-cIDPR potentially binds non-productively in an upside-down fashion. Results highlight the key role of the “northern” ribose in the interaction of cADPR with CD38

CD38/cADPR Signaling Pathway in Airway Disease: Regulatory Mechanisms

Asthma is an inflammatory disease in which proinflammatory cytokines have a role in inducing abnormalities of airway smooth muscle function and in the development of airway hyperresponsiveness. Inflammatory cytokines alter calcium (Ca2+) signaling and contractility of airway smooth muscle, which results in nonspecific airway hyperresponsiveness to agonists. In this context, Ca2+ regulatory mechanisms in airway smooth muscle and changes in these regulatory mechanisms encompass a major component of airway hyperresponsiveness. Although dynamic Ca2+ regulation is complex, phospholipase C/inositol tris-phosphate (PLC/IP3) and CD38-cyclic ADP-ribose (CD38/cADPR) are two major pathways mediating agonist-induced Ca2+ regulation in airway smooth muscle. Altered CD38 expression or enhanced cyclic ADP-ribosyl cyclase activity associated with CD38 contributes to human pathologies such as asthma, neoplasia, and neuroimmune diseases. This review is focused on investigations on the role of CD38-cyclic ADP-ribose signaling in airway smooth muscle in the context of transcriptional and posttranscriptional regulation of CD38 expression. The specific roles of transcription factors NF-kB and AP-1 in the transcriptional regulation of CD38 expression and of miRNAs miR-140-3p and miR-708 in the posttranscriptional regulation and the underlying mechanisms of such regulation are discussed

A novel fluorescent probe for NAD-consuming enzymes

A novel, fluorescent NAD derivative is processed as substrate by three different NAD-consuming enzymes. The new probe has been used to monitor enzymatic activity in a continuous format by changes in fluorescence and, in one case, to directly visualize alternative reaction pathways

The Grizzly, November 5, 1982

Clinic Offered for Ski-Bums • Outstanding Choral Students Chosen • U.C. Poses for Posterity • Letters to the Editor: Greeks Piqued • USGA Notes • President\u27s Corner • Ropes and Chains or Can You Eat Plasterboard? • Protheatre Presents Comedy at its Best • The Messiah is Coming! • The World\u27s Largest Picture at Ursinus: Get Yours Now! • Take That, West Chester! • Soccer Season Ends With Win Over Widener • Bear Pack Waltzes to Victory • Bears Battle But Lose War • Lady Bears Dominatehttps://digitalcommons.ursinus.edu/grizzlynews/1087/thumbnail.jp

The Grizzly, October 15, 1982

Students for Peace and Progress Get Started • Homecoming 1982 • Annual Parents Day a Success • Letters to the Editor • Opinion: Sorority Rushing Needs Revision • Lantern Format Undecided • Dance-a-Thon for Lupus • Japan: Big and Real • New Art at Myrin • Bear Booters Win Three • Now Hold it Just a Minute! • Grizzlies Win Third Straight • X-Country Wins • Penn Blasts Lady Bears 3-0https://digitalcommons.ursinus.edu/grizzlynews/1084/thumbnail.jp

Basolateral amygdala bidirectionally modulates stress-induced hippocampal learning and memory deficits through a p25/Cdk5-dependent pathway

Repeated stress has been suggested to underlie learning and memory deficits via the basolateral amygdala (BLA) and the hippocampus; however, the functional contribution of BLA inputs to the hippocampus and their molecular repercussions are not well understood. Here we show that repeated stress is accompanied by generation of the Cdk5 (cyclin-dependent kinase 5)-activator p25, up-regulation and phosphorylation of glucocorticoid receptors, increased HDAC2 expression, and reduced expression of memory-related genes in the hippocampus. A combination of optogenetic and pharmacosynthetic approaches shows that BLA activation is both necessary and sufficient for stress-associated molecular changes and memory impairments. Furthermore, we show that this effect relies on direct glutamatergic projections from the BLA to the dorsal hippocampus. Finally, we show that p25 generation is necessary for the stress-induced memory dysfunction. Taken together, our data provide a neural circuit model for stress-induced hippocampal memory deficits through BLA activity-dependent p25 generation.National Institutes of Health (U.S.) (Grant AG047661)National Institutes of Health (U.S.) (Grant NS051874)JPB FoundationSwiss National Science Foundation (Grant for Prospective Researchers)Human Frontier Science Program (Strasbourg, France) (Long-Term Postdoctoral Fellowship

Cyclic adenosine 5′-diphosphate ribose analogs without a southern ribose inhibit ADP-ribosyl cyclase-hydrolase CD38

Cyclic adenosine 5′-diphosphate ribose (cADPR) analogs based on the cyclic inosine 5′-diphosphate ribose (cIDPR) template were synthesized by recently developed stereo- and regioselective <i>N</i>1-ribosylation. Replacing the base <i>N</i>9-ribose with a butyl chain generates inhibitors of cADPR hydrolysis by the human ADP-ribosyl cyclase CD38 catalytic domain (shCD38), illustrating the nonessential nature of the “southern” ribose for binding. Butyl substitution generally improves potency relative to the parent cIDPRs, and 8-amino-<i>N</i>9-butyl-cIDPR is comparable to the best noncovalent CD38 inhibitors to date (IC₅₀ = 3.3 μM). Crystallographic analysis of the shCD38:8-amino-<i>N</i>9-butyl-cIDPR complex to a 2.05 Å resolution unexpectedly reveals an <i>N</i>1-hydrolyzed ligand in the active site, suggesting that it is the <i>N</i>6-imino form of cADPR that is hydrolyzed by CD38. While HPLC studies confirm ligand cleavage at very high protein concentrations, they indicate that hydrolysis does not occur under physiological concentrations. Taken together, these analogs confirm that the “northern” ribose is critical for CD38 activity and inhibition, provide new insight into the mechanism of cADPR hydrolysis by CD38, and may aid future inhibitor design

'Click cyclic ADP-ribose':A neutral second messenger mimic

Analogues of the potent Ca(2+) releasing second messenger cyclic ADP-ribose (cADPR) with a 1,2,3-triazole pyrophosphate bioisostere were synthesised by click-mediated macrocyclisation. The ability to activate Ca(2+) release was surprisingly retained, and hydrolysis of cADPR by CD38 could also be inhibited, illustrating the potential of this approach to design drug-like signalling pathway modulators

The Grizzly, November 19, 1982

Dorm Intrusion: Attack Prompts Security Changes • Council Approves Precalc • Student Apathy: Who Cares? • Elephants and Donkeys Revived on Campus • President\u27s Corner • Pledging Changes Planned • Commentary: Be a Good Boy, Johnny - Take Back Your Tray • Lewis on Wall Street • Applying for the Job • Robert Hazard: The Grizzly Interview • Final Exam Schedule • Grizzly Paws Boost Football Program • Women\u27s Basketball Set to Have Big Season • X-Country Takes a Disappointing Sixth • Soccer Team Was Tough All Year • Men\u27s Swimming Falls to Dickinson in Openerhttps://digitalcommons.ursinus.edu/grizzlynews/1089/thumbnail.jp