Free Content How Insulin Receptor Substrate Proteins Regulate the Metabolic Capacity of the Liver - Implications for Health and Disease

 Download
(PDF 428.7kb)
 
Download Article:

Abstract:

The liver plays a key role in glucose homeostasis, lipid and energy metabolism. Its function is primarily controlled by the anabolic hormone insulin and its counterparts glucagon, catecholamines and glucocorticoids. Dysregulation of this homeostatic system is a major cause for development of the metabolic syndrome and type 2 diabetes mellitus. The features of the underlying dynamic molecular network that coordinates systemic nutrient homeostasis are less clear. But recently, considerable progress has been made in elucidating molecular pathways and potential factors involved in the regulation of energy and lipid metabolism and affected in diabetic states.

In this review we will focus on important stations in the complex network of molecules that control the balance between glucose production, glucose utilization and regulation of lipid metabolism. Special attention will be paid to the insulin receptor substrate (IRS) proteins with the two major isoforms IRS-1 and IRS-2 as a critical node in hepatic insulin signalling. IRS proteins act as docking molecules to connect tyrosine kinase receptor activation to essential downstream kinase cascades, including activation of the PI-3 kinase or MAPK cascade. IRS-1 and IRS-2 are complementary key players in the regulation of hepatic insulin signalling and expression of genes involved in gluconeogenesis, glycogen synthesis and lipid metabolism. The function of IRS proteins is regulated by their expression levels and posttranslational modifications. This regulation within the dynamic molecular network that coordinates systemic nutrient homeostasis will be outlined in detail under the following conditions: after feeding, during fasting and during exercise. Dysfunction of IRS proteins initially leads to post-prandial hyperglycemia, increased hepatic glucose production, and dysregulated lipid synthesis and is discussed as major pathophysiological mechanism for the development of insulin resistance and type 2 diabetes mellitus.

Understanding the molecular regulation and the pathophysiological modifications of IRS proteins is crucial in order to identify new sites for potential intervention to treat or prevent hepatic insulin resistance and type 2 diabetes mellitus.

Keywords: Liver; diabetes; gene regulation; glucose metabolism; insulin receptor substrate; insulin resistance; insulin signalling; lipid metabolism

Document Type: Research Article

DOI: http://dx.doi.org/10.2174/092986708784534956

Affiliations: Div. of Clinical Chemistry and Pathobiochemistry, Central Laboratory, University Hospital Tubingen, Hoppe-Seyler-Str. 3, D-72076 Tubingen, Germany.

Publication date: June 1, 2008

More about this publication?
  • Current Medicinal Chemistry covers all the latest and outstanding developments in medicinal chemistry and rational drug design. Each issue contains a series of timely in-depth reviews written by leaders in the field covering a range of the current topics in medicinal chemistry. Current Medicinal Chemistry is an essential journal for every medicinal chemist who wishes to be kept informed and up-to-date with the latest and most important developments.
Related content

Tools

Favourites

Share Content

Access Key

Free Content
Free content
New Content
New content
Open Access Content
Open access content
Subscribed Content
Subscribed content
Free Trial Content
Free trial content
Cookie Policy
X
Cookie Policy
ingentaconnect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more