Single-Cell Metabolic Imaging Reveals Glycogen Driven-Adaptations in Endothelial Cells.

Area of Science:

• Metabolic imaging
• Cellular metabolism
• Diabetes research

Background:

• Endothelial dysfunction is central to diabetes and cardiovascular diseases.
• Endothelial cells primarily use glucose, but glycogen metabolism is poorly understood.
• Lack of tools hinders investigation of glycogen's role in endothelial cells.

Purpose of the Study:

• Investigate subcellular glycogen metabolism in live endothelial cells under diabetes-associated stress.
• Characterize glycogen dynamics and its role as an energy reserve.
• Explore alternative substrate metabolism in endothelial cells.

Main Methods:

• Stimulated Raman Scattering (SRS) microscopy for live cell imaging.
• Diabetes-mimicking milieu (high glucose, TNF-α) exposure.
• Glycogen synthase kinase 3 (GSK3) inhibition.
• Pulse-chase experiments.
• Metabolic imaging of glutamine and lactate.

Main Results:

• Endothelial cells store excess glucose as glycogen under high glucose/TNF-α conditions.
• GSK3 inhibition enhances glycogen storage capacity.
• Glycogen is rapidly mobilized during glucose starvation, serving as an energy reserve.
• SRS imaging visualized glutamine and lactate metabolism in endothelial cells for the first time.
• Glycogen-rich cells showed reduced demand for gluconeogenic substrates during glucose deprivation.

Conclusions:

• Glycogen metabolism plays a significant role in endothelial cell energy reserves and stress adaptation.
• Glycogen may modulate stress-responsive metabolic adaptations in endothelial cells.
• Targeting glycogen metabolism offers potential therapeutic strategies for diabetes-induced endothelial dysfunction and cardiometabolic diseases.