Iron overload coupled with low
hepcidin levels are characteristics of hereditary
haemochromatosis. To understand the role of
transferrin receptor (TFR) and intracellular
iron in
hepcidin secretion, Chinese hamster ovary
transferrin receptor variant (CHO TRVb-1) cells were used that express
iron-response-element-depleted human TFRC
mRNA (TFRCâIRE). Results showed that CHO TRVb-1 cells expressed higher basal levels of cell-surface TFR1 than HepG2 cells (2.2-fold; p < 0.01) and following 5 g/L
holotransferrin treatment maintained constitutive over-expression at 24h and 48 h, contrasting the HepG2 cells where the receptor levels significantly declined. Despite this, the intracellular
iron content was neither higher than HepG2 cells nor increased over time under basal or
holotransferrin-treated conditions. Interestingly,
hepcidin secretion in CHO TRVb-1 cells exceeded basal levels at all time-points (p < 0.02) and matched levels in HepG2 cells following treatment. While TFRC
mRNA expression showed expected elevation (2h, p < 0.03; 4h; p < 0.05), slc40a1
mRNA expression was also elevated (2 h, p < 0.05; 4 h, p < 0.03), unlike the HepG2 cells. In conclusion, the CHO TRVb-1 cells prevented cellular
iron-overload by elevating slc40a1 expression, thereby highlighting its significance in the absence of
iron-regulated TFRC
mRNA. Furthermore,
hepcidin response to
holotransferrin treatment was similar to HepG2 cells and resembled the human physiological response.