Pplicable clinical laboratory diagnostics. In this study we show that the erythrocyte ABCG2 Calcitonin (salmon) site levels correspond to the genetic background, thus may reflect the overall tissue Dimethylenastron biological activity expression patterns of this protein. We suggest that the method presented here may provide the basis for the development of generally applicable membrane protein biomarkers. It has been documented that ABCG2 expression is regulated by various xenobiotics, drugs, or stress conditions, e.g. hypoxia ?see [10,11,12,29]. In a larger cohort of donors and hematological patients we are currently studying the role of drug treatment and environmental factors in the erythrocyte expression levels of the ABCG2 protein. These may provide clinically valuable data in the context of drug absorption, distribution, and toxicity, as well as predicting treatment efficiency and potential multidrug resistance. A quantitative measure of the expression of ABCG2, shaping ADMETox properties and drug sensitivity, should significantly promote a personalized approach in pharmacology. Although the ABCG2 expression in the cancerous tissues does not uniquely depend on the overall genetic background (special regulatory changes or gene rearrangements may occur), the red cell ABCG2 protein levels may reflect the physiological tissue expression patterns, which modify the efficiency or 16985061 toxicity of the cancer drug treatment. These questions are still to be explored in larger scale studies.ABCG2 in the Erythrocyte MembraneFigure 4. Pedigrees of two families carrying different ABCG2 premature stop mutations ?co-segregation of the heterozygous mutation with reduced erythrocyte ABCG2 expression levels. Blood samples obtained from the 14 family members of the two healthy volunteer probands, carrying the premature stop mutations (see Fig. 3 -indicated with arrowheads) were analyzed for ABCG2 expression and the respective mutations. The RBC-G2 factor values, reflecting ABCG2 expression in erythrocytes, are shown in parentheses. Family members not available for blood donation are labeled by N.A. doi:10.1371/journal.pone.0048423.gIn addition, the above simple methodology may be applicable for a wide variety of clinically relevant membrane proteins, expressed in the erythrocytes. As shown in Figure 5 and in theSupplementary Materials, the plasma membrane calcium pump (PMCA) or Glycophorin A can be quantitatively detected in the human red cells by this method. In our current experiments, notFigure 5. Expression of three selected membrane proteins in the erythrocyte membrane in family 2 with members having a heterozygous frameshift mutation on one of the ABCG2 alleles (labeled as+/2), as compared to ABCG2 wild type individuals of the same family (labeled as+/+). Family members are labeled according to generations (I, II, III), and blood samples obtained (1?). doi:10.1371/journal.pone.0048423.gABCG2 in the Erythrocyte Membranepresented here in detail, we have found that the above described technology can be applied to quantitatively assess the expression of several other membrane proteins (including ABCA1, ABCB6, ABCC1, ABCC3, and ABCC4). We are currently performing population studies to evaluate the significance of SNPs and mutations in the expression levels of these membrane proteins.Figure SCalibration of 5F10 antibody binding andsaturation. (TIF)Materials S(DOC)Supporting InformationFigure SAcknowledgmentsWe appreciate the help in these experiments of Dr. Krisztina Truta-Feles and Edit Szabo. ?Western blot analysi.Pplicable clinical laboratory diagnostics. In this study we show that the erythrocyte ABCG2 levels correspond to the genetic background, thus may reflect the overall tissue expression patterns of this protein. We suggest that the method presented here may provide the basis for the development of generally applicable membrane protein biomarkers. It has been documented that ABCG2 expression is regulated by various xenobiotics, drugs, or stress conditions, e.g. hypoxia ?see [10,11,12,29]. In a larger cohort of donors and hematological patients we are currently studying the role of drug treatment and environmental factors in the erythrocyte expression levels of the ABCG2 protein. These may provide clinically valuable data in the context of drug absorption, distribution, and toxicity, as well as predicting treatment efficiency and potential multidrug resistance. A quantitative measure of the expression of ABCG2, shaping ADMETox properties and drug sensitivity, should significantly promote a personalized approach in pharmacology. Although the ABCG2 expression in the cancerous tissues does not uniquely depend on the overall genetic background (special regulatory changes or gene rearrangements may occur), the red cell ABCG2 protein levels may reflect the physiological tissue expression patterns, which modify the efficiency or 16985061 toxicity of the cancer drug treatment. These questions are still to be explored in larger scale studies.ABCG2 in the Erythrocyte MembraneFigure 4. Pedigrees of two families carrying different ABCG2 premature stop mutations ?co-segregation of the heterozygous mutation with reduced erythrocyte ABCG2 expression levels. Blood samples obtained from the 14 family members of the two healthy volunteer probands, carrying the premature stop mutations (see Fig. 3 -indicated with arrowheads) were analyzed for ABCG2 expression and the respective mutations. The RBC-G2 factor values, reflecting ABCG2 expression in erythrocytes, are shown in parentheses. Family members not available for blood donation are labeled by N.A. doi:10.1371/journal.pone.0048423.gIn addition, the above simple methodology may be applicable for a wide variety of clinically relevant membrane proteins, expressed in the erythrocytes. As shown in Figure 5 and in theSupplementary Materials, the plasma membrane calcium pump (PMCA) or Glycophorin A can be quantitatively detected in the human red cells by this method. In our current experiments, notFigure 5. Expression of three selected membrane proteins in the erythrocyte membrane in family 2 with members having a heterozygous frameshift mutation on one of the ABCG2 alleles (labeled as+/2), as compared to ABCG2 wild type individuals of the same family (labeled as+/+). Family members are labeled according to generations (I, II, III), and blood samples obtained (1?). doi:10.1371/journal.pone.0048423.gABCG2 in the Erythrocyte Membranepresented here in detail, we have found that the above described technology can be applied to quantitatively assess the expression of several other membrane proteins (including ABCA1, ABCB6, ABCC1, ABCC3, and ABCC4). We are currently performing population studies to evaluate the significance of SNPs and mutations in the expression levels of these membrane proteins.Figure SCalibration of 5F10 antibody binding andsaturation. (TIF)Materials S(DOC)Supporting InformationFigure SAcknowledgmentsWe appreciate the help in these experiments of Dr. Krisztina Truta-Feles and Edit Szabo. ?Western blot analysi.
