P2Y₂ nucleotide receptor activation enhances the aggregation and self-organization of dispersed salivary epithelial cells

Abstract

El-Sayed FG, Camden JM, Woods LT, Khalafalla MG, Petris MJ, Erb L, Weisman GA. P2Y2 nucleotide receptor activation enhances the aggregation and self-organization of dispersed salivary epithelial cells. Am J Physiol Cell Physiol 307: C83-C96, 2014. First published April 24, 2014 doi:10.1152/ajpcell.00380.2013.-Hyposalivation resulting from salivary gland dysfunction leads to poor oral health and greatly reduces the quality of life of patients. Current treatments for hyposalivation are limited. However, regenerative medicine to replace dysfunctional salivary glands represents a revolutionary approach. The ability of dispersed salivary epithelial cells or salivary gland-derived progenitor cells to self-organize into acinarlike spheres or branching structures that mimic the native tissue holds promise for cell-based reconstitution of a functional salivary gland. However, the mechanisms involved in salivary epithelial cell aggregation and tissue reconstitution are not fully understood. This study investigated the role of the P2Y2 nucleotide receptor (P2Y2R), a G protein-coupled receptor that is upregulated following salivary gland damage and disease, in salivary gland reconstitution. In vitro results with the rat parotid acinar Par-C10 cell line indicate that P2Y2R activation with the selective agonist UTP enhances the self-organization of dispersed salivary epithelial cells into acinar-like spheres.Other results indicate that the P2Y2R-mediated response is dependent on epidermal growth factor receptor activation via the metalloproteases ADAM10/ADAM17 or the ␣5␤1 integrin/Cdc42 signaling pathway, which leads to activation of the MAPKs JNK and ERK1/2. Ex vivo data using primary submandibular gland cells from wild-type and P2Y2R

P2 Receptors as Therapeutic Targets in the Salivary Gland: From Physiology to Dysfunction

“…In rodent salivary glands, P2Y 2 R expression is negligible under physiological conditions. Interestingly, freshly dispersed salivary epithelial cells significantly upregulated P2Y 2 R expression and activity as a function of time when placed in culture El-Sayed et al, 2014), consistent with a possible role for P2Y 2 R in the cellular response to stress. P2Y 2 R upregulation also occurs in the in vivo ductal ligation model of salivary gland inflammation and fibrosis (Ahn et al, 2000) and has been similarly seen in other in vivo models of stress and inflammation, i.e., intestinal inflammation (Grbic et al, 2008), rat vascular neointima formation after balloon angioplasty (Seye et al, 1997), collared rabbit carotid arteries (Seye et al, 2002), glomerulonephritis (Rennert et al, 2018), myocardium of rats with congestive heart failure (Granado et al, 2015) and mouse models of the autoimmune disease SS Woods et al, 2018).…”

“…Following de-ligation, residual cells in damaged salivary glands can regenerate the gland through proliferation, migration and self-organization (Takahashi et al, 1998;Man et al, 2001;Kishi et al, 2006;Aure et al, 2015), thereby restoring salivary gland function, i.e., increasing the secretion rate of saliva with a normal ion and protein composition (Scott et al, 1999;Osailan et al, 2006). Concurrent with these glandular changes, functional P2Y 2 R expression, which is very low under homeostatic conditions, is robustly increased in salivary epithelial cells in response to ductal ligation and P2Y 2 R expression returns to basal low levels following de-ligation and subsequent recovery of the salivary gland (Ahn et al, 2000;El-Sayed et al, 2014). These findings are in agreement with previous studies demonstrating P2Y 2 R upregulation in epithelial cells in response to tissue damage and inflammation Schrader et al, 2005;Degagne et al, 2009;Woods et al, 2018), suggesting that the P2Y 2 R is an important component in the repair and regeneration of damaged salivary glands.…”

P2Y 2 Nucleotide Receptor Prompts Human Cardiac Progenitor Cell Activation by Modulating Hippo Signaling

“…These results reinforce the emerging view of P2Y 2 R as pro-proliferative in various experimental models including hepatocytes 15, 44 , corneal endothelial cells 45 and pancreatic duct epithelial cells 46 . In addition, P2Y 2 R-induced migration in hCPCs is consistent with pro-migratory responses of P2Y 2 R in fibroblasts 24 , salivary 14 and corneal epithelial cells 13 . Whether ex vivo manipulation of hCPCs by UTP preconditioning or P2Y 2 R overexpression improves transplanted hCPC homing, expansion and overall reparative potential for injured myocardium remains to be assessed.…”

“…P2Y 2 R plays a central role in intracellular signaling by enabling extracellular ATP and UTP to promote regenerative responses in a variety of tissues. P2Y 2 R regulates corneal epithelia wound healing 13 and salivary gland reconstitution 14 by inducing cell migration, liver regeneration by promoting hepatocyte proliferation 15 , and reepithelialization following experimental colitis 16 and inflammatory bowel disease 17 . On the stem cell level, UTP is a potent stimulant of human hematopoietic stem cell (hHSC) migration 18 .…”

Purinergic receptors as potential therapeutic targets in Alzheimer's disease

“…Also within the C-terminus of the P2Y 2 R, two Src-homology-3 (SH3) binding sites directly interact with and activate the tyrosine kinase Src, enabling P2Y 2 R-mediated transactivation of growth factor receptors, including the EGFR (Liu et al, 2004). Lastly, the P2Y 2 R has been shown to activate the α-secretases, ADAM10 and ADAM17, which promotes the release of membrane-bound receptor ligands, including growth factors (Ratchford et al, 2010; El-Sayed et al, 2014), and the cleavage of APP to form non-amyloidogenic sAPPα peptide (Camden et al, 2005; Kong et al, 2009). …”