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Insulin receptor-associated protein tyrosine phosphatase(s): role in insulin action
1Polypeptide Hormone Laboratory, McGill University, Montreal, Quebec, Canada.
Abstract:
Protein tyrosine phosphatases (PTPs) play a critical role in regulating insulin action in part through dephosphorylation of the active (autophosphorylated) form of the insulin receptor (IRK) and attenuation of its tyrosine kinase activity. Following insulin binding the activated IRK is rapidly internalized into the endosomal apparatus, a major site at which the IRK is dephosphorylated in vivo. Studies in rat liver suggest a complex regulatory process whereby PTPs may act, via selective IRK tyrosine dephosphorylation, to modulate IRK activity in both a positive and negative manner. Use of peroxovanadium (pV) compounds, shown to be powerful PTP inhibitors, has been critical in delineating a close relationship between the IRK and its associated PTP(s) in vivo. Indeed the in vivo administration of pV compounds effected activation of IRK in parallel with an inhibition of IRK-associated PTP activity. This process was accompanied by a lowering of blood glucose levels in both normal and diabetic rats thus implicating the IRK-associated PTP(s) as a suitable target for defining a novel class of insulin mimetic agents. Identification of the physiologically relevant IRK-associated PTP(s) should facilitate the development of drugs suitable for managing diabetes mellitus.
Insights
Protein tyrosine phosphatases (PTPs) regulate insulin signaling by dephosphorylating the insulin receptor (IRK). Inhibiting PTPs with peroxovanadium compounds activates IRK and lowers blood glucose, suggesting PTPs as a target for diabetes drugs.
Area of Science:
- Biochemistry
- Cellular Biology
- Endocrinology
Background:
- Protein tyrosine phosphatases (PTPs) are key regulators of insulin action.
- PTPs dephosphorylate the active insulin receptor (IRK), modulating its tyrosine kinase activity.
- Insulin receptor internalization into endosomes is a primary site for IRK dephosphorylation in vivo.
Purpose of the Study:
- To investigate the role of PTPs in insulin receptor regulation.
- To explore the potential of PTP inhibitors as a novel class of insulin mimetic agents for diabetes management.
Main Methods:
- Utilized peroxovanadium (pV) compounds as potent PTP inhibitors.
- Administered pV compounds in vivo to normal and diabetic rats.
- Assessed IRK activity and PTP activity following pV compound administration.
Main Results:
- Peroxovanadium compounds inhibited IRK-associated PTP activity in vivo.
- Inhibition of PTPs led to the activation of the insulin receptor (IRK).
- Administration of pV compounds resulted in decreased blood glucose levels in both normal and diabetic rats.
Conclusions:
- IRK-associated PTPs are critical targets for modulating insulin signaling.
- PTP inhibitors show promise as a novel therapeutic strategy for managing diabetes mellitus.
- Identification of specific IRK-associated PTPs will advance the development of new diabetes drugs.