Poster Presentation ANZOS-Breakthrough Discoveries Joint Annual Scientific Meeting 2018

Stabilization of Beta Catenin in hypothalamic cell lines (#240)

Mohammed Z Rizwan 1 2 3 4 , Peter Shepherd 4 5 , Alex Tups 2 3 4 , David R Grattan 1 3 4
  1. Department of Anatomy, University of Otago, Dunedin, New Zealand
  2. Department of Physiology, University of Otago, Dunedin, New Zealand
  3. Centre for Neuroendocrinology, University of Otago, Dunedin, New Zealand
  4. Maurice Wilkins Centre for Molecular Biodiscovery, Auckland, New Zealand
  5. Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand

Beta-catenin is a signalling molecule in the Wnt-signalling pathway, which has typically been associated with embryogenesis and tumorigenesis. More recently, new lines of evidence suggest that it may also be involved in the pathogenesis of type-2 diabetes. In its active form, beta-catenin acts together with the transcription factor T cell-specific transcription factor-7-like 2 (TCF7L2) to activate target genes of the Wnt-signalling pathway. Impairment in this signal transduction pathway in the pancreas may contribute to the development of type-2 diabetes. The role of the hypothalamus in controlling glucose homeostasis is becoming well-recognized, and we have recently found that Wnt signalling is activated in the hypothalamus in response to feeding-related hormones. To investigate possible mechanisms of feeding-induced stabilization of beta-catenin, we have used adult mouse hypothalamic cell lines that express the phenotype for various metabolic neuropeptides and receptors involved in central regulation of metabolism. We surveyed a variety of potential hormone factors that can simulate the effect of feeding: forskolin, exendin-4 and MTII (an α-MSH analogue). After treatment, we firstly measured NPY and AgRP secretion. Treatment with these factors did not affect the secretion of either neuropeptide. After applying KCl to depolarise the cells, however, there was significantly greater release of both AgRP and NPY from treated cells compared with vehicle-controls, indicative of an effect on synthesis or vesicle trafficking. We next treated these cell lines with forskolin and discovered that in one of the cell line, all the Wnt-responsive genes analyzed were markedly up-regulated. In addition we found an increase in total beta-catenin protein expression following treatment with either forskolin, exendin-4 or MTII. These data suggest that the treatment has increased the pool of neuropeptide available for release. These results are consistent with the role of beta-catenin in regulating a feeding response through a central mechanism.