P2Y2 purinergic receptor activation is essential for efficient hepatocyte proliferation in response to partial hepatectomy

Abstract

cellular nucleotides via activation of P2 purinergic receptors influence hepatocyte proliferation and liver regeneration in response to 70% partial hepatectomy (PH). Adult hepatocytes express multiple P2Y (G protein-coupled) and P2X (ligand-gated ion channels) purinergic receptor subtypes. However, the identity of key receptor subtype(s) important for efficient hepatocyte proliferation in regenerating livers remains unknown. To evaluate the impact of P2Y2 purinergic receptor-mediated signaling on hepatocyte proliferation in regenerating livers, wild-type (WT) and P2Y2 purinergic receptor knockout (P2Y2Ϫ/Ϫ) mice were subjected to 70% PH. Liver tissues were analyzed for activation of early events critical for hepatocyte priming and subsequent cell cycle progression. Our findings suggest that early activation of p42/44 ERK MAPK (5 min), early growth response-1 (Egr-1) and activator protein-1 (AP-1) DNA-binding activity (30 min), and subsequent hepatocyte proliferation (24 -72 h) in response to 70% PH were impaired in P2Y2Ϫ/Ϫ mice. Interestingly, early induction of cytokines (TNF-␣, IL-6) and cytokine-mediated signaling (NF-B, STAT-3) were intact in P2Y2Ϫ/Ϫ remnant livers, uncovering the importance of cytokine-independent and nucleotidedependent early priming events critical for subsequent hepatocyte proliferation in regenerating livers. Hepatocytes isolated from the WT and P2Y2Ϫ/Ϫ mice were treated with ATP or ATP␥S for 5-120 min and 12-24 h. Extracellular ATP alone, via activation of P2Y2 purinergic receptors, was sufficient to induce ERK phosphorylation, Egr-1 protein expression, and key cyclins and cell cycle progression of hepatocytes in vitro. Collectively, these findings highlight the functional significance of P2Y2 purinergic receptor activation for efficient hepatocyte priming and proliferation in response to PH. extracellular ATP; P2Y2 purinergic receptors; partial hepatectomy; hepatocyte proliferation; liver regeneration LIVER REGENERATION IN RESPONSE to partial hepatectomy (PH) is a highly coordinated process involving a complex interplay of multiple humoral factors and integration of cell signaling in parenchymal and nonparenchymal cells (45). In response to PH, adult hepatocytes are "reprogrammed" to undergo cell cycle progression and proliferation until tissue restitution is achieved. The factor(s) that trigger cell cycle progression of hepatocytes in response to PH as well as cellular events that play a role in the reestablishment of quiescence upon the completion of liver growth are not well understood.In response to 70% PH, the remnant livers are subjected to elevated shear stress and trigger the release of factors believed to play key roles in the initiation of proliferative response in hepatocytes (1, 15, 60). Cellular stress including shear stress is a potent trigger for ATP release. Extracellular ATP, via the activation of cell surface P2 purinergic receptors, influences cell signaling, activation of transcription factors, and gene expression (5, 18). In recent years, extracellular ATP is begin...

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

“…Restoration of P2Y 2 R levels by lentiviral-mediated overexpression augments their proliferative and migratory capabilities (Figure 3). 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 .…”

Congenital heart defects and left ventricular non-compaction in males with loss-of-function variants inNONO

“…To determine if the NONO allele present in subject 1 might produce a truncated protein, we performed a western blot analysis for NONO on protein extracted from the same cell lines 33. This analysis was performed using an N-terminal anti-NONO antibody directed at amino acids 7–22 (FNLEKQNHTPRKHHQH) of human NONO [NM_001145408.1].…”

P2X1‐regulated IL‐22 secretion by innate lymphoid cells is required for efficient liver regeneration

“…The nucleotide, adenosine triphosphate (ATP), is released at early time points post‐PH . Extracellular nucleotides modulate cellular injury, proliferation, and crosstalk by specific purinergic P2Y (G‐protein coupled) and P2X (ligand‐gated ion channel) receptors . Purinergic receptors are expressed on many cell types, including intrahepatic lymphocytes of which cNK, NKT, and ILC1 represent the largest fraction .…”

“…(8,13) Extracellular nucleotides modulate cellular injury, proliferation, and crosstalk by specific purinergic P2Y (G-protein coupled) and P2X (ligand-gated ion channel) receptors. (8,(14)(15)(16) Purinergic receptors are expressed on many cell types, including intrahepatic lymphocytes of which cNK, NKT, and ILC1 represent the largest fraction. (17,18) However, the cellular and molecular mechanisms downstream of extracellular nucleotides receptors that promote liver regeneration are still unclear.…”