The ubiquitin-proteasome pathway is a new partner for the... : Current Opinion in Clinical Nutrition & Metabolic Care (original) (raw)
Anabolic and catabolic signals
The ubiquitin-proteasome pathway is a new partner for the control of insulin signaling
UMR INRA1235-INSERM 449, Mécanismes moléculaires du diabète, Faculté de Médecine Laënnec, 69008 Lyon, France
Correspondence to Sophie Rome, UMR INRA1235-INSERM 449, Mécanismes moléculaires du diabète, Faculté de Médecine Laënnec, 69008 Lyon, France Tel: +33 4 78 77 10 46; fax: +33 4 78 77 89 62; e-mail: [email protected]
Abbreviations
IDE: insulin-degrading enzyme
IRS: insulin receptor substrate
PI3-K: phosphatidylinositol 3-kinase
PKB: protein kinase B
PPAR: peroxisome proliferator-activated receptor
SOCS: suppressor of cytokine signaling
SREBP: sterol regulatory element-binding protein
Abstract
Purpose of review
Insulin signaling is a transitory effect that has to be tightly controlled in magnitude and duration in order to maintain cell homeostasis. Recent reports have demonstrated that members of the ubiquitin-proteasome pathway represent new partners that have to be taken into account for the regulation of insulin action.
Recent findings
The protein amounts of the different signaling molecules involved in insulin action are regulated by their rates of synthesis and degradation. The ubiquitin-proteasome system is involved in the internalization of the insulin receptor, in the control of the amount of insulin receptor substrates 1 and 2, and in insulin degradation. Finally, ubiquitination and sumoylation regulate transcription factors and nuclear receptors that mediate insulin-induced gene expression.
Summary
It is well known from transgenic models that inappropriate levels of signaling molecules strongly affect insulin action. In humans also, several reports have provided evidence of altered levels of key proteins involved in insulin action in pathologies such as type 2 diabetes. The relationship between these abnormalities and the ubiquitin-proteasome pathway has yet to be clarified, but clarifying the role of ubiquitination in insulin action will certainly lead to a better understanding of insulin resistance.
© 2004 Lippincott Williams & Wilkins, Inc.