Reversible regulation of P2Y₂ nucleotide receptor expression in the duct-ligated rat submandibular gland

Abstract

Ligation of the main excretory duct of the rat submandibular gland (SMG) produces a pronounced atrophy that is reversed upon ligature removal. Based on previous studies by our group and others suggesting that P2Y(2) nucleotide receptors are upregulated in response to tissue damage, we hypothesized that P2Y(2) receptor activity and mRNA levels would increase after duct ligation and return to control levels after ligature removal. Our results support this hypothesis. Intracellular Ca(2+) mobilization in response to the P2Y(2) receptor agonist UTP in SMG cells was increased significantly after ligation periods of 1.5 to 7 days, whereas no significant response was observed in the contralateral, nonligated gland. P2Y(2) receptor mRNA, as measured by semiquantitative RT-PCR, increased about 15-fold after 3 days of ligation. These increases reverted to control levels by 14 days after ligature removal. In situ hybridization revealed that the changes in P2Y(2) receptor mRNA abundance occurred mostly in acinar cells, which also were more adversely affected by ligation, including an increase in the appearance of apoptotic bodies. These findings support the idea that P2Y(2) receptor upregulation may be an important component of the response to injury in SMG and that recovery of normal physiological function may signal a decreased requirement for P2Y(2) receptors.

Stimulation of Cl− Secretion via Membrane-restricted Ca2+ Signaling Mediated by P2Y Receptors in Polarized Epithelia

“…Firstly, it is because the expression of certain P2Y receptor subtypes does only occur when the epithelial cells are cultivated on permeable supports, which allows polarized differentiation (14,16,26). This is supported by other studies (27,28) showing prominent changes of P2Y receptor expression as a function of short term culturing of salivary gland cells. Down-regulation of UDP-activated receptor, probably P2Y6, during culture on glass coverslips has also been suggested in tracheal epithelial cells isolated from P2Y 2 -receptor-deficient mice (29).…”

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

“…The capacity of dispersed salivary epithelial cells or salivary glandderived progenitor cells to reassemble into acinar-like spheres or branching structures has been previously assessed (84,90,118), but little is known about the signaling events involved in these differentiation processes. In the present study, we determined that the P2Y 2 nucleotide receptor (P2Y 2 R), known to be upregulated during salivary gland damage and disease (1,99,113), plays a role in the aggregation and self-organization of dispersed salivary epithelial cells into acinar-like spheres. Our in vitro data using the rat parotid acinar (Par-C10) cell line show that P2Y 2 R activation by UTP significantly enhances the migration, aggregation, and self-organization of dispersed Par-C10 cells into acinar-like spheres (Fig.…”

“…In addition, the P2Y 2 R is upregulated upon disruption of salivary gland tissue homeostasis (113) and in salivary glands of the NOD.B10 mouse model of SS-like autoimmune exocrinopathy (99). In a classic model of salivary gland regeneration, P2Y 2 R expression and activity increase due to tissue atrophy caused by a 3-day ductal ligation in rat submandibular gland (SMG), whereas P2Y 2 R expression and activity levels and glandular morphology resemble unligated controls 14 days after deligation (1). Collectively, these findings suggest that P2Y 2 R upregulation plays a role in salivary gland regeneration.…”

Purinergic receptors in the endocrine and exocrine pancreas

“…Fifth, we need to address the issue of tissue culture and its effect on P2Y receptors and ion channels that they regulate. In studies on salivary glands, it was shown that duct obstruction, inflammation and culture markedly increase P2Y 2 receptor expression [87,134,135]. Also in a recent study on human pancreas it was shown that the pattern for expression of P2Y 2 and P2X 7 receptors can change in pathological conditions like chronic pancreatitis, pancreatic cancer and purinergic receptors on other than epithelial cells need to be considered [128].…”