Regulation of Large Conductance Ca2+-activated K+ (BK) Channel β1 Subunit Expression by Muscle RING Finger Protein 1 in Diabetic Vessels

Abstract

Background: Impaired BK channel function in diabetic vessels is associated with decreased BK channel ␤1 subunit (BK-␤1) expression. Results: Muscle RING finger protein 1 (MuRF1) physically interacts with BK-␤1 and accelerates BK-␤1 proteolysis. Conclusion: Increased MuRF1 expression is a novel mechanism underlying diabetic BK channelopathy and vasculopathy. Significance: MuRF1 is a potential therapeutic target of BK channel dysfunction and vascular complications in diabetes.

Role of Nrf2 Signaling in the Regulation of Vascular BK Channel β1 Subunit Expression and BK Channel Function in High-Fat Diet–Induced Diabetic Mice

“…Cells between passages 5 and 8 were transduced with adenoviral green fluorescent protein (GFP) vectors carrying the Nrf2 gene (Ad-GFP-Nrf2) or Nrf2 short hairpin RNAs (shRNAs) (Ad-GFP-Nrf2 shRNA) at 50 multiplicity of infection (MOI) for 48 h as we previously described (11,16). Transduction of Ad-GFP or Ad-GFP-U6-Scramble-RNAi served as controls.…”

“…Immunoblot analysis was performed in isolated arteries from mice and cultured coronary SMCs, as we reported previously (9,11,16). Rabbit anti-Nrf2 (1:200; catalog #sc-722; Santa Cruz Biotechnology), rabbit anti–HO-1 (1:200; catalog #sc-10789; Santa Cruz Biotechnology), and mouse anti-MuRF1 (1:200; catalog #sc-398608; Santa Cruz Biotechnology), mouse GAPDH-horseradish peroxidase (HRP) (1:5,000; catalog #HRP-6004; Proteintech), and mouse anti–β-actin-HRP (1:10,000; catalog #A3854; Sigma-Aldrich, St. Louis, MO) antibodies were used in this study.…”

“…In addition, the NF-κB/p65 can be directly activated by reactive oxygen species (ROS) through phosphorylation of NF-κB/p65 (15). We have recently identified that the muscle ring finger protein 1 (MuRF1), a muscle-specific E3 ligase, is one of the target genes of NF-κB in vascular SMCs (16). An increase in the protein expressions of NF-κB/p50 and NF-κB/p65 was responsible for MuRF1-mediated BK-β1 protein degradation in type 1 diabetic mouse arteries (16).…”

“…We have recently identified that the muscle ring finger protein 1 (MuRF1), a muscle-specific E3 ligase, is one of the target genes of NF-κB in vascular SMCs (16). An increase in the protein expressions of NF-κB/p50 and NF-κB/p65 was responsible for MuRF1-mediated BK-β1 protein degradation in type 1 diabetic mouse arteries (16). However, the upstream signaling leading to dysregulation of NF-κB expression in diabetic vessels is unclear.…”

Regulation of Coronary Arterial Large Conductance Ca²⁺-Activated K⁺ Channel Protein Expression and Function by n-3 Polyunsaturated Fatty Acids in Diabetic Rats

“…The underlying mechanisms responsible for reduced BK-β 1 protein expression in diabetic vessels are multifactorial and depend on disease models and tissue beds. For instance, a reduction of the BK-β 1 protein level was due to the acceleration of BK-β 1 proteolysis in STZ-induced diabetic mouse aortas [44], while a downregulation of BK-β 1 expression was also associated with nuclear factor of activated T-cells c3 (NFATc3)-dependent transcription in the mesentery arteries of high-fat diet-induced obese/prediabetic mice [45]. Accordingly, future studies should be performed to determine whether the RING finger protein 1 or NFATc3 is necessary for increased BK-β 1 expression with n-3 PUFA treatment in diabetic rats.…”