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Adenosine triphosphate release and purinergic (P2) receptor-mediated secretion in small and large mouse cholangiocytes.

ABSTRACT: Adenosine triphosphate (ATP) is released from cholangiocytes into bile and is a potent secretogogue by increasing intracellular Ca²(+) and stimulating fluid and electrolyte secretion via binding purinergic (P2) receptors on the apical membrane. Although morphological differences exist between small and large cholangiocytes (lining small and large bile ducts, respectively), the role of P2 signaling has not been previously evaluated along the intrahepatic biliary epithelium. The aim of these studies therefore was to characterize ATP release and P2-signaling pathways in small (MSC) and large (MLC) mouse cholangiocytes. The findings reveal that both MSCs and MLCs express P2 receptors, including P2X4 and P2Y2. Exposure to extracellular nucleotides (ATP, uridine triphosphate, or 2',3'-O-[4-benzoyl-benzoyl]-ATP) caused a rapid increase in intracellular Ca²(+) concentration and in transepithelial secretion (I(sc)) in both cell types, which was inhibited by the Cl(-) channel blockers 5-nitro-2-(-3-phenylpropylamino)-benzoic acid (NPPB) or niflumic acid. In response to mechanical stimulation (flow/shear or cell swelling secondary to hypotonic exposure), both MSCs and MLCs exhibited a significant increase in the rate of exocytosis, which was paralleled by an increase in ATP release. Mechanosensitive ATP release was two-fold greater in MSCs compared to MLCs. ATP release was significantly inhibited by disruption of vesicular trafficking by monensin in both cell types.These findings suggest the existence of a P2 signaling axis along intrahepatic biliary ducts with the "upstream" MSCs releasing ATP, which can serve as a paracrine signaling molecule to "downstream" MLCs stimulating Ca²(+)-dependent secretion. Additionally, in MSCs, which do not express the cystic fibrosis transmembrane conductance regulator, Ca²(+)-activated Cl(-) efflux in response to extracellular nucleotides represents the first secretory pathway clearly identified in these cholangiocytes derived from the small intrahepatic ducts.

SUBMITTER: Woo K

PROVIDER: S-EPMC2967625 | biostudies-literature | 2010 Nov

REPOSITORIES: biostudies-literature

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Adenosine triphosphate release and purinergic (P2) receptor-mediated secretion in small and large mouse cholangiocytes.

Woo Kangmee K Sathe Meghana M Kresge Charles C Esser Victoria V Ueno Yoshiyuki Y Venter Julie J Glaser Shannon S SS Alpini Gianfranco G Feranchak Andrew P AP

Hepatology (Baltimore, Md.) 20101101 5

<h4>Unlabelled</h4>Adenosine triphosphate (ATP) is released from cholangiocytes into bile and is a potent secretogogue by increasing intracellular Ca²(+) and stimulating fluid and electrolyte secretion via binding purinergic (P2) receptors on the apical membrane. Although morphological differences exist between small and large cholangiocytes (lining small and large bile ducts, respectively), the role of P2 signaling has not been previously evaluated along the intrahepatic biliary epithelium. The ...[more]

PMID: 20827720

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Project description:Ovulation disorders are a serious problem for humans and livestock. In female rodents, kisspeptin neurons in the anteroventral periventricular nucleus (AVPV) are responsible for generating a luteinizing hormone (LH) surge and consequent ovulation. Here, we report that adenosine 5-triphosphate (ATP), a purinergic receptor ligand, is a possible neurotransmitter that stimulates AVPV kisspeptin neurons to induce an LH surge and consequent ovulation in rodents. Administration of an ATP receptor antagonist (PPADS) into the AVPV blocked the LH surge in ovariectomized (OVX) rats treated with a proestrous level of estrogen (OVX + high E2) and significantly reduced the ovulation rate in proestrous ovary-intact rats. AVPV ATP administration induced a surge-like LH increase in OVX + high E2 rats in the morning. Importantly, AVPV ATP administration could not induce the LH increase in Kiss1 KO rats. Furthermore, ATP significantly increased intracellular Ca2+ levels in immortalized kisspeptin neuronal cell line, and coadministration of PPADS blocked the ATP-induced Ca2+ increase. Histologic analysis revealed that the proestrous level of estrogen significantly increased the number of P2X2 receptor (an ATP receptor)-immunopositive AVPV kisspeptin neurons visualized by tdTomato in Kiss1-tdTomato rats. The proestrous level of estrogen significantly increased varicosity-like vesicular nucleotide transporter (a purinergic marker)-immunopositive fibers projecting to the vicinity of AVPV kisspeptin neurons. Furthermore, we found that some hindbrain vesicular nucleotide transporter-positive neurons projected to the AVPV and expressed estrogen receptor α, and the neurons were activated by the high E2 treatment. These results suggest that hindbrain ATP-purinergic signaling triggers ovulation via activation of AVPV kisspeptin neurons.SIGNIFICANCE STATEMENT Ovulation disorders, which cause infertility and low pregnancy rates, are a serious problem for humans and livestock. The present study provides evidence that adenosine 5-triphosphate, acting as a neurotransmitter in the brain, stimulates kisspeptin neurons in the anteroventral periventricular nucleus, known as the gonadotropin-releasing hormone surge generator, via purinergic receptors to induce the gonadotropin-releasing hormone/luteinizing hormone surge and ovulation in rats. In addition, histologic analyses indicate that adenosine 5-triphosphate is likely to be originated from the purinergic neurons in the A1 and A2 of the hindbrain. These findings may contribute to new therapeutic controls for hypothalamic ovulation disorders in humans and livestock.

Project description:BackgroundOrganoids, which enable disease modeling and drug screening closer to an in vivo environment, can be isolated and grown from organs such as the brain, small intestine, kidney, lungs, and liver. To facilitate the establishment of liver and small intestinal organoids, we developed efficient protocols for cholangiocytes and intestine crypts collecting and organoid culturing.MethodsCholangiocytes were collected from intrahepatic bile ducts, the gallbladder, and small intestine crypts by gravity settling and multistep centrifugation methods. The cells isolated were embedded with Matrigel and grew in three-dimensional spheroids in a suitable culture medium. The stability of organoid cells was assessed by subculture, cryopreservation, and thawing. RNA and DNA extraction of organoids, as well as immunostaining procedure, were also optimized. Hand-picking procedures were developed and performed to ensure similar growth characteristics of organoids.ResultsA large number of cholangiocytes and small intestine crypts were collected under these protocols. Cholangiocytes developed into cyst-like structures after 3-4 days in Matrigel. After 1-2 weeks of cultivation, small intestinal organoids (in-orgs) developed buds and formed a mature structure. Compared to organoids derived from the gallbladder, cholangiocyte organoids (Cho-orgs) from intrahepatic the bile ducts grew more slowly but had a longer culture term, expressed the cholangiocytes markers Krt19 and Krt7, and recapitulated in vivo tissue organization.ConclusionsOur protocols simplified the cell collection procedure and avoided the possibility of exposing tissue-derived stem cells to mechanical damage or chemical injury by gravity settling and multistep centrifugation. In addition, our approach allowed similar growth characteristics of organoids from different mammalian tissue sources. The protocol requires 2-4 weeks to establish a stable organoid growth system. Organoids could be stably passaged, cryopreserved, and recovered under protocol guidance. Besides, the organoids of cholangiocytes and small intestines retained their original tissue characteristics, such as tissue-specific marker expression, which prepares them for further experiments such as preclinical in vitro trials and mechanism research studies.

Dataset Information

Adenosine triphosphate release and purinergic (P2) receptor-mediated secretion in small and large mouse cholangiocytes.

Publications

Adenosine triphosphate release and purinergic (P2) receptor-mediated secretion in small and large mouse cholangiocytes.

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