Multiple plasma proteins control atrial natriuretic peptide (ANP) aggregation.

Area of Science:

• Biochemistry
• Molecular Biology
• Cardiovascular Research

Background:

• Human alpha-atrial natriuretic peptide (alpha-hANP) is an amyloidogenic peptide implicated in isolated atrial amyloidosis.
• Alpha-hANP aggregation is inhibited by binding to apolipoprotein A-I (apo A-I) dimers found in high-density lipoproteins (HDL).
• Plasma demonstrates significantly higher amyloid inhibitory activity than HDL alone, suggesting other binding factors exist.

Purpose of the Study:

• To identify plasma-binding proteins, in addition to apo A-I dimer, that bind alpha-hANP and inhibit its aggregation.
• To investigate the complete network of amyloidogenic and antiamyloidogenic peptides in plasma.

Main Methods:

• Incubation of whole human plasma with radiolabeled alpha-hANP.
• Two-dimensional gel electrophoresis followed by autoradiography to detect macromolecular complexes.
• Mass spectrometry analysis of radioactive spots to identify binding proteins.

Main Results:

• Novel binding proteins for alpha-hANP were identified in human plasma.
• Albumin, alpha-1 antitrypsin, orosomucoid, and an apo A-IV-TTR complex were identified as additional ANP-binding factors.
• These proteins, like apo A-I dimer, inhibit alpha-hANP aggregation in vitro.

Conclusions:

• Plasma contains multiple proteins that bind alpha-hANP and prevent its aggregation, beyond HDL-associated apo A-I.
• These findings expand the known network of amyloidogenic and antiamyloidogenic interactions in the cardiovascular system.
• The identified proteins represent potential therapeutic targets for managing alpha-hANP-related amyloidosis.