Natriuretic peptide pharmacogenetics: Membrane metallo-endopeptidase (MME): Common gene sequence variation, functional characterization and degradation

• Published in: Journal of molecular and cellular cardiology Vol. 49; no. 5; pp. 864 - 874
• Main Authors: Pereira, Naveen L., Aksoy, Pinar, Moon, Irene, Peng, Yi, Redfield, Margaret M., Burnett, John C., Wieben, Eric D., Yee, Vivien C., Weinshilboum, Richard M.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.11.2010
• Subjects: Animals; Atrial Natriuretic Factor - genetics; Autophagy; Base Sequence; Cardiovascular; Cercopithecus aethiops; COS Cells; Genetic Variation; Genomics; Haplotypes - genetics; Humans; Isoenzymes - genetics; Linkage Disequilibrium - genetics; Membrane metallo-endopeptidase; Models, Molecular; Molecular Chaperones - metabolism; Natriuretic peptides; Neprilysin - genetics; Neprilysin - metabolism; Pharmacogenetics; Polymorphism; Polymorphism, Single Nucleotide - genetics; Proteasome Endopeptidase Complex - metabolism; Protein Processing, Post-Translational; Sequence Analysis, DNA; Valine - genetics; Membrane metallo-endopeptidase; Pharmacogenetics; Natriuretic peptides; Polymorphism
• ISSN: 0022-2828; 1095-8584; 1095-8584
• DOI: 10.1016/j.yjmcc.2010.07.020

Membrane metallo-endopeptidase (MME), also known as neutral endopeptidase 24.11 (EC 3.4.24.11), is involved in the metabolism of natriuretic peptides that play a key role in modulating cardiac structure and function. Common genetic variation in MME has not been addressed by resequencing the gene using DNA from different ethnic populations. We set out to identify and functionally characterize common genetic variation in MME in three ethnic groups. DNA samples from 96 European-American, 96 African-American, and 96 Han Chinese-American healthy subjects were used to resequence MME. Ninety polymorphisms, 65 novel, were identified, including 8 nonsynonymous single nucleotide polymorphisms (nsSNPs). Expression constructs for the nsSNPs were created and COS-1 cells were transfected with constructs for wild type (WT) and variant allozymes. Recombinant proteins were analyzed by quantitative Western blot analysis and by a one-step fluorometric assay. A significant reduction in enzyme activity (21% of WT) and immunoreactive protein (29% of WT) for the Val73 variant allozyme was observed. Proteasome-mediated degradation and autophagy participated in the degradation of this variant allozyme. The chaperone proteins, BiP and GRP94, were upregulated after transfection with Val73 MME, suggesting protein misfolding, compatible with conclusions based on the MME X-ray crystal structure. Multiple novel polymorphisms of MME were identified in three ethnic groups. The Val73 variant allozyme displayed a significant decrease in MME protein quantity and activity, with degradation mediated by both proteasome and autophagy pathways. This polymorphism could have a significant effect on the metabolism of natriuretic peptides. ►Membrane metallo-endopeptidase (MME), also known as neutral endopeptidase 24.11 is involved in the metabolism of natriuretic peptides that play a key role in modulating cardiac structure and function. ►MME was resequenced in three ethnic groups resulting in identification of 90 polymorphisms of which 65 were novel, including 8 nonsynonymous single nucleotide polymorphisms (nsSNPs) of which 7 were not described before. ►The functional effects of the nsSNPs on expressed protein levels and enzyme activity was studied in an in-vitro cell based system leading to the identification of a significant reduction in enzyme activity (21% of wild-type) and immunoreactive protein (29% of wild-type) for the Met73Val variant allozyme ►Proteasome-mediated degradation and autophagy participated in the degradation of the Met73Val allozyme and was associated with increased expression of the chaperone proteins, BiP and GRP94 suggesting protein misfolding, compatible with conclusions based on the MME X-ray crystal structure. ►The Met73Val variant allozyme could have a significant effect on the metabolism of natriuretic peptides.