DNAJB3 attenuates ER stress through direct interaction with AKT

Area of Science:

• Molecular Biology
• Cellular Stress Response
• Metabolic Disorders

Background:

• Metabolic stress in type 2 diabetes mellitus (T2DM) downregulates heat shock proteins (HSPs) like DNAJB3, contributing to insulin resistance (IR).
• HSP induction can improve insulin sensitivity by counteracting metabolic stress-induced signaling pathway dysregulation.
• Key pathways affected include JNK1, IKKβ, and subsequent inactivation of IRS-1/IRS-2, alongside activation of the PI3K-PKB/AKT pathway.

Purpose of the Study:

• To elucidate the molecular mechanism by which DNAJB3 mitigates metabolic stress and improves glucose homeostasis.
• To investigate the direct interaction between DNAJB3 and AKT1 and its functional consequences.
• To determine the role of DNAJB3-AKT1 interaction in GLUT4 translocation and ER stress protection.

Main Methods:

• Protein pull-down assays to identify interacting partners.
• Isothermal titration calorimetry (ITC) to quantify binding affinity.
• Protein modeling and docking to identify the binding interface.
• Cellular assays to assess GLUT4 translocation and ER stress response.

Main Results:

• DNAJB3 directly interacts with AKT1, with binding affinity quantified by ITC.
• The AKT1-DNAJB3 complex is localized in the cytoplasm and ER, facilitating AS160 mobilization for glucose transport.
• DNAJB3-mediated GLUT4 translocation and protection against tunicamycin-induced ER stress are dependent on AKT1 activity.

Conclusions:

• DNAJB3 directly interacts with AKT1, forming a functional complex that alleviates ER stress.
• This interaction promotes GLUT4 translocation, enhancing glucose uptake and improving insulin sensitivity.
• DNAJB3 represents a potential therapeutic target for managing metabolic stress in T2DM.