NFAT2 drives both Orai3 transcription and protein degradation by harnessing the differences in epigenetic landscape

Abstract

The functional significance of any protein in physiological processes and pathological conditions is largely dependent on its expression profile. Therefore, nature has evolved several autonomous mechanisms to regulate protein expression such as transcription, translation, post-translational modifications and epigenetic changes. These processes are typically controlled by distinct molecular players with no overlapping roles. Here, we reveal that same transcription factor, NFAT2 regulates both transcription and lysosomal degradation of Orai3 oncochannel in a context dependent manner. We demonstrate that NFAT2 drives Orai3 transcription and thereby increases Orai3 levels in non-metastatic cancerous cells. While in invasive and metastatic cancerous cells, NFAT2 induces Orai3 lysosomal degradation by transcriptionally enhancing the levels of MARCH8 E3 ubiquitin ligase. Our biochemical and super-resolution microscopy data show that MARCH8 physically interacts with Orai3 eventually resulting in its degradation. Mechanistically, the dichotomy in regulation of Orai3 expression emerges from the differences in the epigenetic landscape of MARCH8. We uncover that the MARCH8 promoter is highly methylated in non-metastatic cancerous cells and hence NFAT2 does not induce MARCH8 mediated Orai3 degradation in these cells. Importantly, we demonstrate that MARCH8 restricts pancreatic cancer metastasis by targeting Orai3 degradation thereby highlighting pathophysiological importance of this signaling module. Taken together, we report a unique and clinically relevant scenario wherein nature has commissioned the same transcription factor to both enhance and curtail the expression of a target protein. Highlights[tpltrtarr] NFAT2 transcriptionally upregulates Orai3 Ca2+ channel in non-metastatic cells [tpltrtarr]NFAT2 induces Orai3 lysosomal degradation via MARCH8 E3 ubiquitin ligase in metastatic cells [tpltrtarr]The dichotomy in NFAT2s function is an outcome of differences in the methylation status of MARCH8 promoter [tpltrtarr]MARCH8 inhibits pancreatic cancer metastasis by driving Orai3 degradation Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=199 SRC="FIGDIR/small/628081v2_ufig1.gif" ALT="Figure 1"> View larger version (48K): org.highwire.dtl.DTLVardef@1292480org.highwire.dtl.DTLVardef@1b5b61org.highwire.dtl.DTLVardef@c4483org.highwire.dtl.DTLVardef@16607f8_HPS_FORMAT_FIGEXP M_FIG C_FIG