Elucidating the role of Mitoferrin (Mfrn), Iron Regulatory Proteins (IRP1 and IRP2) and Hephaestin (Heph) in Iron Metabolism by tagSNP and Protein-Protein Interaction (PPI) analysis

Velaga, Ravindrath M. (2014) Elucidating the role of Mitoferrin (Mfrn), Iron Regulatory Proteins (IRP1 and IRP2) and Hephaestin (Heph) in Iron Metabolism by tagSNP and Protein-Protein Interaction (PPI) analysis. Doctoral thesis, London Metropolitan University.

Abstract

Precisely how Hephaestin (Heph) facilitate iron release from cells is poorly understood. The work in this thesis tried to establish the role of different iron metabolic proteins, Mitoferrin (Mfrn), IRPs and Heph in iron homeostasis. Analysis of 18 tagSNPs in the Mfrn gene was carried out in an Asian-Caucasian population to establish any correlation between the Mfrn tagSNPs, haemoglobin levels and birth weight in the presence of covariates such as sex of the fetus, gestational age and mother's booking weight. Two-way ANCOVA analysis was carried out to check if the covariates have any influence on the dependent variable in the presence of fixed factors. From the ANCOVA analysis of Mfrn tagSNPs it can be concluded that neither the haemoglobin levels nor the birth weight are dependent on the genotype, fetal sex, nor on their interaction.

Owing to the significance in identifying the interacting partners of IRPs and Heph to understand more about their role in iron metabolism, protein-protein interaction studies were also carried out. IRPs and Heph genes were successfully cloned with One-Strep tag. Full length clones were sequence confirmed for any variation after PCR. Before carrying out immunoprecipitation to identify the interacting partners, transfection efficiency, viability and the role of magnetic particles on K562 cells was performed by using IRPs and Heph cloned with One-Strep tag. Lipofectamine-LTX plus transfection had more viable cells and higher efficiency compared with magnetic-assisted transfection. Also, this study confirms that magnetic nanoparticles do not have any adverse or significant effect on IRPs during the transfection. An unsuccessful attempt was made to identify the interacting partners of IRPs and Heph by immunoprecipitation. The current thesis work also involved identification of a potential ferroxidase. Ceruloplasmin (Cp) was used as a postive control. Non-denaturing gel eletrophoresis of the K562, MDA-MB-231 and PNT2-C2 cell fractions confirmed the presence of the extra band establishing the ubiquitous nature of the band. Mass spectrometry analysis identified the excised band as Calreticulin (CALR). This is the first report of calreticulin having ferroxidase activity.

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