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Purinergic Regulation of Bile Ductular Secretion
Published in Gianfranco Alpini, Domenico Alvaro, Marco Marzioni, Gene LeSage, Nicholas LaRusso, The Pathophysiology of Biliary Epithelia, 2020
The concept of extracellular nucleotides as regulatory molecules is not new; Burnstock first advanced it in the 1950s.1–3 However, this idea did not gain widespread acceptance until distinct nucleotide receptors were first identified in the 1970s and cloned in the 1980s and beyond. As a group these receptors were initially referred to as purinergic receptors, since the first nucleotide receptor agonists studied were adenosine polyphosphates, such as ATP. The term purinergic receptor, however, is no longer valid, since it is clear that pyrimidinergic nucleotides, such as UTP, can activate these receptors as well. Hence, the most appropriate name for these receptors may be nucleotide receptors, although the term purinergic receptors remains in common usage.
Chemoreception in Aquatic Invertebrates
Published in Robert H. Cagan, Neural Mechanisms in Taste, 2020
Barry W. Ache, William E. S. Carr
Purinergic receptors for purine nucleotides are present on the external membrane surfaces of many types of internal tissues of mammals, including both peripheral and central nervous tissue,76,77 cardiovascular tissue,78 visceral smooth muscle,79 and others.80 Burnstock81 recognized that purinergic receptors are not homogeneous and introduced the terms P1 and P2 to distinguish between two major types. Among their distinctive features is the fact that the P1-type has a potency sequence of adenosine ⩾ AMP > ADP ⩾ ATP, whereas the P2-type has a potency sequence of ATP ⩾ ADP > AMP ⩾ adenosine. We now know that decapod crustaceans possess chemosensory receptors with marked similarities to both of these two types of purinergic receptors.
Secretion, Alveolar Processing, and Turnover of Pulmonary Surfactant
Published in Jacques R. Bourbon, Pulmonary Surfactant: Biochemical, Functional, Regulatory, and Clinical Concepts, 2019
The most potent group of single agonists on surfactant secretion are agents that activate protein kinase C. In addition, when assayed on the same substrate, protein kinase C was found to be more active than cAMP-dependent protein kinase in type II cells.26 Hence, data available thus far lead one to ascribe the major role to protein kinase C and the mediators which activate this enzyme. The signal transduction mechanism which sets protein kinase C in action in type II cells, however, is not as well understood as the role of β-receptors for cAMP-dependent kinase activation. Recent convergent data indicate that purinergic receptors are also involved in the control of surfactant secretion (see Section III.C). Both P1 and P2 purinergic receptor-mediated mechanisms have been suggested.27 They appear to act, however, through different messengers. Although P2 receptor-mediated signal appears to be responsible for protein kinase C activation through phosphatidylinositol phosphate hydrolysis to inositol phosphate and release of calcium from internal stores,28,29 PI receptors, like β-adrenergic receptors, appear to act through an increase in cAMP production.29
Pharmacotherapeutic Options for Chronic Refractory Cough
Published in Expert Opinion on Pharmacotherapy, 2020
Adenosine triphosphate (ATP) is a major danger-associated molecule released during inflammation that is recognized by purinergic receptors. There are two types of purinergic receptors identified to date, including the P2Y (responding mainly to adenosine and adenosine monophosphate) and P2X receptors (responding relatively specifically to ATP) [50]. Importantly, the P2X3 receptor is not detected in human brain tissues (https://www.proteinatlas.org/ENSG00000109991-P2RX3), but primarily on afferent neuron of the sensory C-fibers, making it a promising target in treating peripheral sensory neuropathic conditions like CRC [51]. In pre-clinical studies, ATP stimulation induces action potentials in C-fibers, which is inhibited by P2X3 receptor antagonists [52]. In humans, ATP inhalation causes cough either in patients with chronic cough and healthy controls [53].
Metabolic pathways and metabolites shaping innate immunity
Published in International Reviews of Immunology, 2020
The energetics of cellular metabolic pathways are mainly depends on ATP (Adenosine triphosphate), which is considered an energy currency of the cell. The extracellular ATP and its consituents or derivatives binds with the family of purinergic receptors that are expressed in various tissues such as adipose tissues, kidney, heart and brain and play a vital role in various biological process, particularly in neuromodulatory functions in the nervous system. The second review in this issue by Zyma et al. discusses the role of purinergic receptors in immunity and its functional maneuvering in various pathophysiological processes (2). The article will be interesting to broad readers of neuroimmunology and medical chemistry or researchers working on development of small molecules for modulation of purinergic receptor for various physiological conditions (Figure-1).
Research progress of P2X7 receptor in inflammatory bowel disease
Published in Scandinavian Journal of Gastroenterology, 2019
Purinergic receptors can be divided into two main categories: P1 (adenosine) and P2 (ATP) receptors. According to the difference in molecular structure and characteristics, P2 receptors can be segmented into ATP-gated trimeric ion-gated channels and G-protein-coupled receptors [18–20]. Both receptors can be further segmented into more specific subtypes. The P2X7 receptor is the most important member of the ion-gated P2X family which is a group of polypeptide chains composed of 595 amino acids. Its N-terminal sequence structure is highly conservative and has high homology with other members of the P2X receptor family. Interestingly, its C-terminal sequence has low hydrophobicity and no homology with other sequences, leading to the unique physiological function of the P2X7 receptor [21,22].