Gene expression profiling analysis of copper homeostasis in Arabidopsis thaliana

As a result of copper essentiality for life, plants and most other organisms have developed a conserved and complex network of proteins to handling Cu in order to prevent its deficit and to avoid its potentially toxic effects. To better understand regulation of Cu homeostasis in plants, we use adult plant of Arabidopsis thaliana to provide an integrated view of how Cu status affects the expression of genes involved in cellular Cu homoeostasis. In doing so, we use real-time RT-PCR to compare shoot and roots transcriptional responses to Cu. We measure changes in the abundance of transcripts encoding transporters, chaperones and P-type ATPases and correlated those changes with variation of Cu content in both tissues. Our results indicated that in both tissues transcript levels of COPT2, 4, and ZIP2 transporters and CCH chaperone were significantly down-regulated comparing to controls plants in response to Cu excess. In contrast, Cu chaperones ATX1, CCS, COX17-1 including two putative mitochondrial chaperones (At3g08950; At1g02410) were up-regulated under similar conditions. Regarding P-type ATPases, a reduction of HMA1, PAA1, PAA2, and RAN1 transcript levels in shoot after Cu exposure was observed, while HMA5 transcripts increased exclusively in roots. In plants growing under Cu-deficient conditions, COPT2, ZIP2, HMA1, andPAA2, were significantly up-regulated in shoots. Thus, our results indicated a common transcriptional regulation pattern of transporters and chaperone components, in particular transcriptional changes of COPT2, ZIP2, and CCH showed an inverse relation with Cu content suggesting that these proteins are required to avoid excess and deficit of Cu.