Heparanase Overexpression Induces Glucagon Resistance and Protects Animals From Chemically-Induced Diabetes
Heparanase, a protein with enzymatic and non-enzymatic properties, contributes towards disease progression and prevention. In the current study, a fortuitous observation in transgenic mice globally overexpressing heparanase (hep-tg) was the discovery of improved glucose homeostasis. We examined the mechanisms that contribute towards this improved glucose metabolism. Heparanase overexpression was associated with enhanced GSIS and hyperglucagonemia, in addition to changes in islet composition and structure. Strikingly, the pancreatic islet transcriptome was greatly altered in hep-tg mice with over 2000 genes differentially expressed versus control. The upregulated genes were enriched for diverse functions including cell death regulation, extracellular matrix component synthesis, and pancreatic hormone production. The downregulated genes were tightly linked to regulation of the cell cycle. In response to multiple low-dose STZ, hep-tg animals developed less severe hyperglycemia compared to WT, an effect likely related to their beta cells being more functionally efficient. In animals given a single, high dose of STZ, causing severe and rapid development of hyperglycemia related to the catastrophic loss of insulin, hep-tg mice continued to have significantly lower blood glucose. In these mice, protective pathways were uncovered for managing hyperglycemia and include augmentation of FGF21 and GLP-1. This study uncovers the opportunity to utilize properties of heparanase in management of diabetes.
- Received June 22, 2016.
- Accepted September 27, 2016.
- © 2016 by the American Diabetes Association.