Molecular and cellular insights into iron regulation

Mehta, K. 2012. Molecular and cellular insights into iron regulation. PhD thesis University of Westminster School of Life Sciences

TitleMolecular and cellular insights into iron regulation
TypePhD thesis
AuthorsMehta, K.
Abstract

The iron hormone hepcidin is regarded as the main iron homeostatic regulator in

the human body. It is predominantly produced by hepatocytes in response to

systemic iron excess. However, since the cellular and molecular mechanisms

involved in hepcidin expression are not fully understood, this project involved

studying hepcidin expression and the role of the pro-region of the hepcidin prohormone in regulation of iron homeostasis.

Iron overdose in Chinese hamster ovary-transferrin receptor variant (CHO TRVb1)

cells resulted in increased hepcidin peptide secretion after 30 min and 2 hours

(p<0.03) as well as 24 and 48 hours (p<0.01). Also, partial characterisation of the previously unknown CHO-gene sequences of Hfe, Slc40-a1 and Irp2, was

achieved. To determine the effect of intracellular iron overload on hepcidin

expression, recombinant transferrin receptor 1 (rec-TfR1) HepG2 cells were

created which express modified TfR1 to maximise iron uptake. Upon

holotransferrin (5 g/L) treatment these cells showed significantly increased iron uptake which was in contrast to the response by Wt HepG2 cells. Also, it was

shown for the first time that hepcidin peptide secretion increased upon iron

overdose to HepG2 cells after 30 min, 2,4,24 and 48 hours (p<0.05). Also,

holotransferrin treatment (5 g/L) increased hepcidin mRNA levels; in Wt HepG2

cells by 0.6 fold (on average) after 30 min, 2,4,6 and 24 hours and in rec-TfR1

HepG2 cells by 0.5 fold after 2 h (p<0.02). Gene expression studies of TfR1,

SLC40-A1, and HFE upon iron overdose showed opposing functionalities of TfR1

and SLC40-A1 in maintaining intracellular iron homeostasis and emphasised the

significance of HFE in hepcidin induction. Additionally, localisation studies with the pre-pro derivative of preprohepcidin identified its presence in the nucleus,

suggesting its involvement in the gene regulation process and thus possible

participation in maintaining iron homeostasis.

In conclusion, rec-TfR1 HepG2 cells partially resemble haemochromatotic cells

and the findings indicate that hepcidin regulation involves the interaction between several iron-related genes and the extracellular and intracellular iron levels.

YearMay 2012
FileKosha_MEHTA.pdf
Publication dates
CompletedMay 2012

Related outputs

Iron enhances hepatic fibrogenesis through TGF-β activation
Mehta, K., Briones-Orta, M., Manka P., Coombes, J.D., Williams, R., Patel, V.B. and Syn, W-K. 2016. Iron enhances hepatic fibrogenesis through TGF-β activation. Hepatology. 64 (1 suppl), p. 360A.

Betaine, in context
Mehta, K. and Patel, V. 2015. Betaine, in context. in: Preedy, V.R. (ed.) Betaine: chemistry, analysis, function and effects Royal Society of Chemistry.

Hepcidin transcription and peptide secretion are governed by different regulatory mechanisms
Mehta, K., Patel, V., Busbridge Mark, Renshaw, D., Zariwala, M.G., Evans, R. and Farnaud, S. 2013. Hepcidin transcription and peptide secretion are governed by different regulatory mechanisms. American Journal of Hematology. 88, p. E55.

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