PhD Scientific Days 2021

MO_III_L: Molecular Sciences III. Lectures

Examining the Modulation of the Plasma Membrane Calcium Pump PMCA4b in Erythroid Cells

Text of the abstract

Introduction: PMCA4b is an ATP-driven calcium pump encoded by the ATP2B4 gene. This protein is responsible for several cellular functions and has a major role in maintaining low calcium levels in platelets and erythrocytes. In genome-wide association studies (GWAS) single nucleotide polymorphisms (SNPs) within a haplotype in the ATP2B4 gene were associated with resistance to a severe form of malaria among children. Individuals that carry the minor haplotype show a decreased expression of PMCA4b in the red blood cell membrane. The genetic area of the haplotype is a predicted erythroid-specific enhancer region, but the molecular mechanisms of this regulation are not known.
Aims: Our aim was to examine the molecular mechanisms responsible for the association between the SNPs in the minor haplotype in the ATP2B4 gene and the reduced expression of PMCA4b in erythroid cells.
Methods: To examine the promoter activity of the ATP2B4 haplotype, four regions were examined separately in which the SNPs within the haplotype are located. HEK (human embryonic kidney) cells and erythroid cell lines HEL92 and K562 were transfected with luciferase-coding plasmids containing the examined regions. The potential promoter activity of the examined regions was determined by dual-luciferase assay.
Results: Dual-luciferase measurements showed a large difference between the erythroid and HEK cell lines. The erythroid-specific regulatory region described by Lessard et al. (2017) showed a significant promoter activity in the HEL92 and K562 erythroid cell lines, while not in HEK cells. Measurements with the same haplotype region containing the minor SNPs showed a decreased level of promoter activity in erythroid cell lines.
Conclusion: Our results provide a better understanding of the molecular mechanisms of the erythroid-specific regulation of the examined region of the PMCA4b calcium transporter. The results indicate that one of the examined regions has an erythroid-specific promoter activity that is decreased when two of the examined SNPs from the minor haplotype are present. The results may have relevance in the susceptibility to malaria.
Funding: PREPARED WITH THE PROFESSIONAL SUPPORT OF THE DOCTORAL STUDENT SCHOLARSHIP PROGRAM OF THE CO-OPERATIVE DOCTORAL PROGRAM OF THE MINISTRY OF INNOVATION AND TECHNOLOGY FINANCED FROM THE NATIONAL RESEARCH, DEVELOPMENT AND INNOVATION FUND.

University and Doctoral School

Semmelweis University, Doctoral School of Molecular Medicine