Aims: In the kidney PT, the divalent metal transporter DMT1 is expressed intracellularly in endosomes and lysosomes (Abouhamed et al. 2006 AJP 290:F1525). An exon12 deletion mRNA splice variant (DE12) has previously been suggested to cause microcytic anemia paired with iron overload in a human patient (Mims et al. 2005 Blood 105:1337). In the course of studying iron status dependence of DMT1 expression in a rat renal PT cell line, we have observed upregulation of various DMT1 splice variants by iron depletion, including DE12. Methods: WKPT cells were treated with 100mM ferric ammonium citrate or desferrioxamine for 36 h, and DMT1 expression was then assayed by semi-quantitative RT-PCR and Western blotting. PCR products were analyzed by sequencing. Results: Iron loading did not affect DMT1 mRNA expression, but attenuated its protein level. In contrast, iron deprivation resulted in marked upregulation of mRNA for a DE12 splice variant, and a concurrent decrease in DMT1 protein expression. The DE12 variant was not detected under either condition in Caco- 2 cells. Use of primers specific for the four major DMT1 isoforms suggested that the DE12 variant in WKPT cells represented mainly the exon1B non-IRE isoform. Moreover, an additional splice variant (DE5) was detected in iron-depleted cells. Conclusions: Upregulation of the DE12 and other mRNA variants in normal rat renal PT cells upon iron depletion suggests that these alternative splicing events may represent responses to, rather than the cause of, iron deficiency in certain cell types.