Research

ATP Release and Purinergic Signaling

Diagram
Potential mechanisms of ATP release
(L-R) Channels, exocytosis with channel insertion, exocytosis

 

ATP release and stimulation of membrane purinergic receptors (P2Y and P2X) is a key mechanism for the autocrine/paracrine regulation of hepatocyte and cholangiocyte transport and bile formation.

Liver disorders associated with impaired bile flow comprise the majority of liver diseases in children. Lack of understanding of how the liver regulates the formation of bile is an obstacle for the development of treatments. Consequently, defining the mechanisms responsible for bile formation will serve as the basis for strategies to improve bile flow and treat these childhood liver disorders. We are exploring a novel pathway in bile formation known as Purinergic signaling, in which ATP is released from liver cells into bile and stimulates cholangiocytes to secrete fluid and increase bile flow.

New Models and Techniques

Our laboratory utilizes novel models of cholangiocytes which allow the direct measurement of fluid secretion. We have also developed a new technique to detect ATP release from living cells.

We have shown that mechanosensitive ATP release depends on intact microtubules and vesicular trafficking pathways. We have identified a population of ATP-enriched vesicles, ranging in size from 0.4 - 1 mm, that undergo fusion and release in response to mechanical stimuli. Additionally, we have shown that the vesicular nucleotide transporter (VNUT), SLC17A9, contributes to ATP vesicle formation in all biliary epithelial models (human, rat, mouse).

We are now working to identify key elements of the intracellular signaling network involved in the trafficking and release of these ATP-enriched vesicles. Our long-term goal is to understand the mechanisms of cellular ATP release and regulation of purinergic signaling.