Proteins lose their nitric oxide stabilizing function after advanced glycosylation

Area of Science:

• Biochemistry
• Physiology
• Endocrinology

Background:

• Nitric oxide (NO) is crucial for vasodilation and platelet inhibition, circulating as S-nitroso adducts of serum albumin.
• Advanced glycosylation end products (AGEs) are implicated in diabetes complications and inactivate free NO.
• The interaction between NO, albumin, and AGEs is critical for understanding NO bioavailability and function.

Purpose of the Study:

• To investigate the impact of advanced glycosylation on the NO-carrying capacity and biological activity of serum albumin.
• To compare the antiproliferative effects of NO-stabilized albumin (SNO-BSA) with other NO donors.
• To determine how AGEs affect NO liberation and NO-dependent cellular responses.

Main Methods:

• Studied antiproliferative effects of SNO-BSA on Con A-stimulated lymphocytes.
• Investigated NO quenching by AGE-BSA.
• Assessed NO-dependent glucose uptake and cGMP generation in peripheral mononuclear cells (PBMC).

Main Results:

• SNO-BSA exhibited potent antiproliferative effects on lymphocytes, surpassing the NO-donor SNAP.
• AGE-BSA effectively quenched NO liberated from SNO-BSA, abolishing NO-dependent cellular activation.
• Advanced glycosylation of BSA impaired its NO-carrying ability and abrogated NO-dependent cellular effects.

Conclusions:

• AGEs significantly reduce NO bioavailability by quenching free NO and impairing albumin's NO-carrying capacity.
• Glycosylation of albumin compromises its physiological roles, including NO delivery and cellular signaling.
• These findings highlight the detrimental effects of AGEs on NO homeostasis, relevant to diabetes pathophysiology.