cCMP and cUMP occur in vivo

Abstract

Mammalian cells contain the cyclic pyrimidine nucleotides cCMP and cUMP. It is unknown whether these tentative new second messenger molecules occur in vivo. We used high performance liquid chromatography quadrupole tandem mass spectrometry to quantitate nucleoside 3′,5′-cyclic monophosphates. cCMP was detected in all organs studied, most notably pancreas, spleen and the female reproductive system. cUMP was not detected in organs, probably due to the intrinsically low sensitivity of mass spectrometry to detect this molecule and organ matrix effects. Intratracheal infection of mice with recombinant Pseudomonas aeruginosa harboring the nucleotidyl cyclase toxin ExoY massively increased cUMP in lung. The identity of cCMP and cUMP in organs was confirmed by high performance liquid chromatography quadrupole time of flight mass spectrometry. cUMP also appeared in serum, urine and faeces following infection. Taken together, this report unequivocally shows for the first time that cCMP and cUMP occur in vivo.

Heterogeneity of pulmonary endothelial cyclic nucleotide response toPseudomonas aeruginosaExoY infection

“…Previous studies have shown that ExoY is a promiscuous cyclase (4,8), capable of elevating cAMP and cGMP in pulmonary endothelial cells (44). Because PAECs and PMVECs display heterogeneity in a variety of cellular responses, including migration and proliferative capacity (28), we sought to determine whether ExoY differentially increases permeability.…”

“…The Gram-negative bacterium Pseudomonas aeruginosa injects a type III secretion system (T3SS) effector protein ExoY directly in host cells, which acts as a promiscuous soluble cyclase once inside the host cell (4,14). ExoY enzymatic activity increases cytosolic cAMP resulting in microtubule destabilization and endothelial barrier disruption (44,52).…”

“…ExoY enzymatic activity increases cytosolic cAMP resulting in microtubule destabilization and endothelial barrier disruption (44,52). In addition to cAMP, emerging evidence suggests ExoY generates other intracellular cyclic nucleotides, including cGMP and cUMP (4,8), in B103 neuroblastoma and A549 lung carcinoma cells and whole lung tissue, although the contribution of specific cell types within the lung to the cyclic nucleotide signature remains unclear. Previously, our lab determined that ExoY ϩ intoxication results in an increase in both cAMP and cGMP in pulmonary microvascular endothelial cells (PMVECs) (44,52), although it remains uncertain whether lung endothelium synthesizes pyrimidine cyclic nucleotides.…”

Recent progress in the field of cIMP research

“…cIMP-induced vasoconstriction may play a role in coronary ischemia/reperfusion injury and/or cardiovascular complications in sleep apnea (Detremmerie et al, 2016). The occurrence of cIMP in only certain pathophysiological settings could be an explanation for the failure to detect cIMP in several biological systems under normal conditions, i.e., without hypoxia (Beste et al, 2013;Hartwig et al, 2014;Bähre et al, 2015). Detremmerie et al (2016) provide evidence in favor of the notion that the pharmacological actions of thymoquinone depend on sGC-catalyzed cIMP formation.…”

“…Studies on various mammalian cell lines and mouse organs failed to detect cIMP (Beste et al, 2013;Hartwig et al, 2014;Bähre et al, 2015), raising doubts about a (patho)physiological role of cIMP (Seifert, 2014). However, the group of Vanhoutte showed that under conditions of hypoxia, sGC switches substrate specificity from GTP to ITP and that the generated cIMP exerts opposite (constrictory) effects on blood vessels to those of cGMP (dilatatory) (Chen et al, 2014;Gao and Vanhoutte, 2014).…”