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Regulation of insulin receptor function by a small molecule insulin receptor activator
Celia Pender1, Ira D Goldfine, Vara Prasad Manchem
1Mount Zion Medical Center, University of California, San Francisco 94143-1616, USA.
Abstract:
In type 2 diabetes mellitus, impaired insulin signaling leads to hyperglycemia and other metabolic abnormalities. TLK19780, a non-peptide small molecule, is a new member of a novel class of anti-diabetic agents that function as activators of the insulin receptor (IR) beta-subunit tyrosine kinase. In HTC-IR cells, 20 microm TLK19780 enhanced maximal insulin-stimulated IR autophosphorylation 2-fold and increased insulin sensitivity 2-3-fold. In contrast, TLK19780 did not potentiate the action of insulin-like growth factor-1, indicating the selectivity of TLK19780 toward the IR. The predominant effect of TLK19780 was to increase the number of IR that underwent autophosphorylation. Kinetic studies indicated that TLK19780 acted very rapidly, with a maximal effect observed 2 min after addition to insulin-stimulated cells. In 3T3-L1 adipocytes, 5 microm TLK19780 enhanced insulin-stimulated glucose transport, increasing both the sensitivity and maximal responsiveness to insulin. These studies indicate that at low micromolar levels small IR activator molecules can enhance insulin action in various cultured cells and suggest that this effect is mediated by increasing the number of IR that are tyrosine-phosphorylated in response to insulin. These studies suggest that these types of molecules could be developed to treat type 2 diabetes and other clinical conditions associated with insulin resistance.
Insights
A novel small molecule, TLK19780, activates insulin receptor (IR) tyrosine kinase, enhancing insulin signaling and glucose transport. This compound shows potential for treating type 2 diabetes and insulin resistance.
Area of Science:
- Biochemistry
- Pharmacology
- Molecular Biology
Background:
- Type 2 diabetes mellitus is characterized by impaired insulin signaling, leading to hyperglycemia.
- Insulin receptor (IR) beta-subunit tyrosine kinase activity is crucial for insulin signal transduction.
- Novel therapeutic strategies targeting IR activation are needed for diabetes treatment.
Purpose of the Study:
- To investigate the effects of TLK19780, a novel small molecule activator of IR beta-subunit tyrosine kinase.
- To determine the mechanism of action and selectivity of TLK19780 on insulin signaling.
- To evaluate the therapeutic potential of TLK19780 in cellular models of insulin resistance.
Main Methods:
- Utilized HTC-IR cells and 3T3-L1 adipocytes for in vitro studies.
- Assessed insulin-stimulated IR autophosphorylation and insulin-like growth factor-1 (IGF-1) potentiation.
- Measured insulin-stimulated glucose transport in adipocytes.
- Performed kinetic studies to determine the time course of TLK19780 action.
Main Results:
- TLK19780 enhanced maximal insulin-stimulated IR autophosphorylation 2-fold in HTC-IR cells.
- TLK19780 increased insulin sensitivity 2-3-fold and potentiated insulin-stimulated glucose transport in 3T3-L1 adipocytes.
- TLK19780 demonstrated selectivity for the IR, with no potentiation of IGF-1 action.
- The primary mechanism involved increasing the number of IR undergoing autophosphorylation rapidly.
Conclusions:
- Small molecule IR activators like TLK19780 can enhance insulin action at low micromolar concentrations.
- TLK19780 effectively improves insulin signaling and glucose uptake in relevant cell models.
- TLK19780 represents a promising therapeutic candidate for type 2 diabetes and conditions associated with insulin resistance.