Linked Life Data

11463579

Source:http://linkedlifedata.com/resource/pubmed/id/11463579

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2001-7-20
pubmed:abstractText
Hyperhomocysteinemia and insulin resistance are independent factors for cardiovascular disease. Most of the angiotoxic effects of homocysteine are related to the formation of homocysteine thiolactone and the consequent increase in oxidative stress. The oxidative stress has also been shown to impair insulin action, therefore leading to insulin resistance. In order to study a putative direct effect of homocysteine on insulin signaling, we have characterized the molecular counter-regulation of the early events in the signal transduction of the insulin receptor, and the metabolic end-point of glycogen synthesis. We employed HTC rat hepatoma cells transfected with the human insulin receptor. A 10 min exposure to homocysteine thiolactone (50 microM) resulted in a significant inhibition of insulin-stimulated tyrosine phosphorylation of the insulin receptor beta-subunit and its substrates IRS-1 and p60-70, as well as their association with the p85 regulatory subunit of phosphatidylinositol 3-kinase. These effects led to impairment of the insulin-stimulated phosphatidylinositol 3-kinase activity, which plays a central role in regulating insulin action. Thus, insulin-stimulated glycogen synthesis was also inhibited by homocysteine thiolactone. To investigate whether oxidative stress was mediating the counter-regulatory effect of homocysteine thiolactone on insulin signaling, we preincubated the cells (5 min) with 250 microM glutathione prior to the incubation with homocysteine (10 min) and subsequent insulin challenge. Glutathione completely abolished the effects of homocysteine thiolactone on insulin-receptor signaling and restored the insulin-stimulated glycogen synthesis. In conclusion, these data suggest that homocysteine thiolactone impairs insulin signaling by a mechanism involving oxidative stress, leading to a defect in insulin action.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0952-5041
pubmed:author
pubmed:issnType
Print
pubmed:volume
27
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
85-91
pubmed:dateRevised
2011-11-17
pubmed:meshHeading
pubmed:year
2001
pubmed:articleTitle
Homocysteine thiolactone inhibits insulin signaling, and glutathione has a protective effect.
pubmed:affiliation
Department of Medical Biochemistry and Molecular Biology, School of Medicine, Investigation Unit, Virgen Macarena University Hospital, Seville, Spain.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't