Spatiotemporal Control of Vascular Ca_V1.2 by α1_C S1928 Phosphorylation

Area of Science:

• Cardiovascular Physiology
• Molecular Cardiology
• Diabetes Research

Background:

• L-type Ca_V1.2 channels regulate cell function through cooperative gating, but the underlying mechanisms remain unclear.
• Diabetic hyperglycemia is associated with altered vascular function, potentially involving Ca_V1.2 channels.

Purpose of the Study:

• To test the hypothesis that phosphorylation of the Ca_V1.2 α1_C subunit at S1928 mediates vascular Ca_V1.2 cooperativity during diabetic hyperglycemia.

Main Methods:

• Utilized a multiscale approach including patch-clamp electrophysiology, super-resolution nanoscopy, proximity ligation assay, calcium imaging, pressure myography, and Laser Speckle imaging.
• Examined Ca_V1.2 cooperativity, α1_C clustering, myogenic tone, and blood flow in human and mouse arterial myocytes/vessels.

Main Results:

• Ca_V1.2 activity and cooperative gating increased in arterial myocytes from diabetic patients and mice, and in wild-type myocytes with elevated glucose.
• These changes were prevented by PKA inhibition or S1928A knock-in, and correlated with α1_C clustering, enhanced Ca²⁺ influx, and reduced blood flow.
• S1928A mutation prevented hyperglycemia-induced Ca_V1.2 remodeling and vascular dysfunction.

Conclusions:

• PKA-dependent S1928 phosphorylation promotes vascular α1_C reorganization into "superclusters" during hyperglycemia and diabetes.
• This process enhances Ca_V1.2 activity and cooperativity, directly impacting vascular reactivity.
• Findings may inform therapeutic strategies for vascular dysfunction in diabetic hyperglycemia.