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Uncovering Clinically Relevant Mutations in Membrane Transporters by Genetic Analysis Linked to the Determination of Erythrocyte Membrane Protein Expression
Author(s) -
Sarkadi Balazs,
Zambo Boglarka,
Bartos Zsuzsanna,
Mozner Orsolya,
Szabo Edit,
Varady Gyorgy,
Homolya Laszlo
Publication year - 2018
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2018.32.1_supplement.541.10
Subject(s) - abcg2 , biology , membrane protein , transporter , solute carrier family , gout , atp binding cassette transporter , biochemistry , genetics , microbiology and biotechnology , gene , membrane
The human red blood cell (RBC) membrane contains more than 300 integral membrane proteins, many with high relevance to disease conditions or pharmacological interventions. We have developed a flow cytometry method for the quantitative determination of the RBC membrane expression levels of selected membrane transporters, and examined their molecular genetic background, as well as their potential value in medical diagnostics as biomarkers. One example presented is the ABCG2 xeno‐ and endobiotic transporter, modulating the absorption and metabolism of pharmacological agents and causing multidrug resistance in cancer. ABCG2 is also involved in uric acid elimination and its impaired function is causative in gout. Analysis of ABCG2 expression in the erythrocyte membranes of healthy volunteers and gout patients showed an enrichment of lower expression levels in the gout patients, correlating with a genetic polymorphism, causing a Q141K variant protein. In addition, based on RBC expression levels, we found stop and frameshift mutations, as well as a relatively frequent, novel ABCG2 mutation (ABCG2‐M71V). This variant, according to cellular expression studies, causes reduced protein expression, although with preserved transporter capability. ABCG2‐M71V expression in vitro could be corrected by therapeutically relevant small molecules, with a potential in allele‐specific gout treatment. Another example is the plasma membrane calcium pump (PMCA4b) of the RBC membrane, which showed heterogeneous RBC expression levels in healthy volunteers. By genetic analysis we found a correlation of the low PMCA4b expression levels with a minor haplotype in the erythroid cell specific regulatory region of this protein. The respective regulatory regions in this minor haplotype have been characterized in detail. These results suggest that personalized medicine should consider the genetic analysis linked to RBC membrane protein expression, and these studies may provide a new tool to uncover clinically important variants of membrane proteins. Support or Funding Information Supported by OTKA K115375, K111678 and FIEK 16‐1‐2016‐0005, NKTH, grants. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .