Copper Chaperone Atox1 Interacts with Cell Cycle Proteins

Abstract

The anaphase-promoting complex (APC) is involved in several processes in the cell cycle, most prominently it facilitates the separation of the sister chromatids during mitosis, before cell division. Because of the key role in the cell cycle, APC is suggested as a putative target for anticancer agents. We here show that the copper chaperone Atox1, known for shuttling copper in the cytoplasm from Ctr1 to ATP7A/B in the secretory pathway, interacts with several APC subunits. Atox1 interactions with APC subunits were discovered by mass spectrometry of co-immunoprecipitated samples and further confirmed using proximity ligation assays in HEK293T cells. Upon comparing wild-type cells with those in which the Atox1 gene had been knocked out, we found that in the absence of Atox1 protein, cells have prolonged G2/M phases and a slower proliferation rate. Thus, in addition to copper transport for loading of copper-dependent enzymes, Atox1 may modulate the cell cycle by interacting with APC subunits.

Inhibition of copper chaperones sensitizes human and canine osteosarcoma cells to carboplatin chemotherapy

“…In addition, a study by Dzebo and colleagues that showed Atox1 also interacts with anaphase‐promoting complex (APC). APC plays a critical role in cell cycle progression via degradation of cyclin‐dependent kinase 4 (CDK4); CDK4 and Cyclin D1 are both needed to promote S phase 32,33 . While these studies show a potential role for atox1 in the cell cycle, they are likely not an explanation for the arrest shown in the cell cycle analysis results.…”

“…APC plays a critical role in cell cycle progression via degradation of cyclin-dependent kinase 4 (CDK4); CDK4 and Cyclin D1 are both needed to promote S phase. 32,33 While these studies show a potential role for (Figure 7). This result is consistent with those of a study that evaluated the effects of knocking out atox1 in breast cancer cells, showing increased time for wound-healing.…”

Copper chaperone ATOX1 is required for MAPK signaling and growth in BRAF mutation-positive melanoma

“…In support for this hypothesis, a phase II clinical trial in triple negative breast cancer patients treated with the Cu chelator tetrathiomolybdate revealed that tumor microenvironment remodeling mediated through the Cu-dependent activity of LOX was ablated. 57,58 Finally, while several reports have suggested that ATOX1 regulates the expression of genes required for cell growth and proliferation by translocating to the nucleus, [51][52][53] ATOX1 is predominately localized to the cytosolic fraction of human melanoma cell lines (Fig. S2a, ESI †).…”

“…Several studies have reported that ATOX1 not only functions in the cytosol but also translocates to the nucleus to facilitate the transcription of genes like CCND1 to drive cell growth and proliferation. [51][52][53] We tested and found that ATOX1 is expressed at undetectable levels in several human cancer cell lines (HPAC and SW48) and an immortalized human cell line (HEK-HT) and is exclusively localized to the cytosolic fraction of A375 and WM88 melanoma cells (Fig. S2a, ESI †).…”

A putative nuclear copper chaperone promotes plant immunity in Arabidopsis

“…Mammalian ATOX1 has been shown to be a copper-dependent transcription regulator; however, details of the functions of ATOX1 in these processes remain elusive ( Itoh et al , 2008 ; Muller and Klomp, 2009 ; Kahra et al , 2015 ; Kamiya et al , 2018 ; Matson Dzebo et al , 2018 ). Previous studies found that ATOX1 could directly bind the GAAAGA promoter sequence as a transcription factor ( Itoh et al , 2008 ; Muller and Klomp, 2009 ; Kamiya et al , 2018 ).…”