Gap Junctional Intercellular Communications Enhanced by Hyaluronic Acid
Yuping Li, Tsutomu Nagira and Toshie Tsuchiya
Division of Medical Devices, National Institute of HealthScience, Kamiyaga 1-18-1, Setagaya-ku, Tokyo, Japan
Abstract: Gap junctional intracellular communications (GJIC) were found in almost all types of vertebrate cells. The p-cells of the endocrine pancreas are connected by gap junctions, and the membrane specializations are thought to provide channels for direct cell-to-cell and cell-to-matrix communications. Previous studies suggested that GJIC may participate in the control of insulin secretion. It has been suggested that hyaluronic acid (HA) increases the function of GJIC—via the expression of Connexin43, a major protein component of gap junctions. However, the effects of HA on insulin secretion and gap-junctions between p-cells remains unclear. To determine whether insulin secretion is affected by gap-junctions after HA-treatment, we exposed HIT-T15, a clonal pancreatic p-cell line, in various concentrations of HA for 72 h, and detected their base- and glucose-stimulated insulin secretion, using an insulin assay kit by ELISA technique. The cellular functions of GJIC were assayed by dye transfer method using the dye solution of Lucifer Yellow. HA-treatment resulted in the enhancement of GJIC and the increase of insulin release. The results obtained in this study suggest that HA increases the insulin secretion of HIT-T15 cells by the enhancement of GJIC.
Key words: hyaluronic acid; gap junction; HIT-T15 cells; insulin secretion.
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