Ahsp

BACKGROUND: Alpha hemoglobin stabilizing protein (AHSP) is a chaperone-like molecule specialized for erythroid series which binds to free α-globin chain. According to this characteristic, AHSP can be considered an important factor which reduces beta thalassemia symptoms. MATERIALS AND METHODS: Reticulocytes RNA extraction and a subsequent cDNA synthesis were performed, followed by Relative qRT-PCR for AHSP, alpha, and beta globin chain genes. The beta actin gene was used as an endogenous reference as well. The relationship between AHSP gene expression, disease severity, and the β/α globin mRNA ratio was studied among different homozygote β-thalassemia patients (mild, moderate and severe) and compared with minor thalassemia and the normal population. RESULTS: Analysis of the β-globin/α-globin mRNA ratio has shown that disease severity enhanced with a decrease in this proportion. Evaluation of the correlation between AHSP gene expression and the average of the β-globin/α-globin expression ratio indicated a significant but indirect relationship in considered groups. Our results demonstrated that the AHSP gene expression increases in accordance with augmentation of clinical symptoms. CONCLUSIONS: Although one of the main reasons for reduced clinical severity in homozygote β-thalassemia can be the high level of AHSP gene expression as a chaperon molecule, our findings indicated that AHSP gene expression decreased in a mild category as compared to that in severe and moderate groups.

Alpha-hemoglobin stabilizing protein (AHSP) is a molecular chaperone that can reduce the damage caused by excess free α-globin to erythroid cells in patients with impaired β-globin chain synthesis. We assessed the effect of sodium phenylbutyrate and sodium valproate, two histone deacetylase inhibitors (HDIs) that are being studied for the treatment of hemoglobinopathies, on the expression of AHSP, BCL11A (all isoforms), γ-globin genes (HBG1/2), and some related transcription factors including GATA1, NFE2, EKLF, KLF4, and STAT3. For this purpose, the K562 cell line was cultured for 2, 4, and 6 days in the presence and absence of sodium phenylbutyrate and sodium valproate. Relative real-time qRT-PCR analysis of mRNA levels was performed to determine the effects of the two compounds on gene expression. Expression of all target mRNAs increased significantly (p < 0.05), except for the expression of BCL11A, which was down-regulated (p < 0.05) in the cells treated with both compounds relative to the levels measured for untreated cells. The findings indicated that sodium valproate had a more considerable effect than sodium phenylbutyrate (p < 0.0005) on BCL11A repression and the up-regulation of other studied genes. γ-Globin and AHSP gene expression continuously increased during the culture period in the treated cells, with the highest gene expression observed for 1 mM sodium valproate after 6 days. Both compounds repressed the expression of BCL11A (-XL, -L, -S) and up-regulated GATA1, NFE2, EKLF, KLF4, STAT3, AHSP, and γ-globin genes expression. Moreover, sodium valproate showed a stronger effect on repressing BCL11A and escalating the expression of other target genes. The findings of this in vitro experiment could be considered in selecting drugs for clinical use in patients with β-hemoglobinopathies.