Study on gene expression control and pathophysiological mechanism of red cell membrane protein 4.2 in normal and disorders of hereditary hemolytic anemia

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The following results were obtained for the recent two years (1997-1999)1.Protein 4.2 (P4.2) anomalies in heredirary hemolytic anemia P4.2 anomalies were identified by quantitative membrane protein analysis from 179 patients in 8Okindreds with hereditary hemolytic anemias. These cases were divided into two types ; i.e., (1) a qualitative anomaly (P4.2 doublet Nagano), and (2) a quantitative anomaly. In qualitative P4.2 anomaly, a point mutation (R488H) was identified on the P4.2 gene in P4.2 doublet Nagano with abnormal P4.2 (72/74kD). In quantitative P4.2 anomalies, mutant genes were detected ; i.e., (1) Mild to moderate P4.2 deficiencies : B3 Fukuoka : G 130R, B3 Kagoshima : 56, 1 nt. del. , B3 Fukuyama I : 112-113, 2nt. del., B3 Fukuyama II : 183, 1 nt. ins., B3 Yamagata : G455R, B3 Okinawa : G714R, B3 Tochigi : R760W, 83 IKumamoto : R760Q B3 Nara : R808H, B3 Nagoya : T837R, B3 Philadelphia : T837M, all mutations were detected on B3 gene. (2) P4.2 complete deficiency : P4.2 mutation … More of the Nippon type (A 142T).2.P4.2 expression in human erythroblasts The expression of P4.2 in normal human erythroid cells was studied utilizing erythroblasts(Ebl) from bone marrow and cultured erythroid cells. P4.2 was first detected in orthochromatic Ebl. Among the various major membrane proteins, the expression of P4.2 was the latest. P4.2 gene mRNA was expressed in early Ebl. During normal erythroid maturation, the expression of seven different P4.2 gene products was observed by Southern blot analysis. Therefore, it can be speculated that P4.2 is expressed after the cytoskeletal network has been constructed and assembled with integral proteins in the membrane lipid bilayer.3.The methylation status of the promoter region of the band3(B3)gene in P4.2 complete deficiency Normally, the 15 CpG sites in the promoter region were almost fully methylated in the B3 gene. In contrast, in P4.2 complete deficiency, three distinct CpG sites(G,K &L) were totally or nearly totally unmethylated in the B3 genes.Although no significant changes of the status of methylation were observed in P4.2 genes.Therefore, the state of methylation might be altered in the disease states probably by changes of the comformation of the DNAs. Less