Potential Role of Dipeptidyl Peptidase-4 in Regulating Mitochondria and Oxidative Stress in Cardiomyocytes

Area of Science:

• Cardiology
• Molecular Biology
• Biochemistry

Background:

• Oxidative stress damages mitochondria, impairs energy production, and contributes to heart disease.
• Dipeptidyl peptidase 4 (DPP4) inhibitors are used for diabetes and heart failure, but results are inconsistent.
• The non-enzymatic functions of DPP4 are not well understood.

Purpose of the Study:

• To investigate the role of DPP4 in cardiomyocytes' response to oxidative stress, independent of its enzymatic activity.
• To determine if inhibiting DPP4 can protect against oxidative stress-induced cardiac damage.

Main Methods:

• Dipeptidyl peptidase 4 (DPP4) was knocked down in cultured cardiomyocytes.
• Cardiomyocytes were exposed to hydrogen peroxide (H2O2) to induce oxidative stress.
• Responses of knocked-down and wild-type cardiomyocytes were compared, assessing cell viability, mitochondrial bioenergetics, reactive oxygen species (ROS) levels, and apoptosis markers.

Main Results:

• Hydrogen peroxide exposure increased DPP4 expression in both cardiomyocyte types.
• Knocking down DPP4 significantly improved cell viability under oxidative stress.
• DPP4 knockdown preserved mitochondrial bioenergetics, reduced intracellular ROS, and decreased apoptosis-associated proteins.
• Inhibition of DPP4 enhanced Nrf2 and PGC-1α signaling pathways.
• DPP4 knockdown increased the activity of antioxidant enzymes superoxide dismutase and catalase.

Conclusions:

• Dipeptidyl peptidase 4 (DPP4) mediates the cardiac response to oxidative stress.
• Inhibiting DPP4 enhances cellular defense mechanisms against oxidative damage in the heart.
• DPP4 may be a therapeutic target for managing oxidative stress in heart disease.