title: High glucose enhances store-operated calcium entry by upregulating ORAI/STIM via calcineurin-NFAT signalling.
abstract: ORAI and stromal interaction molecule (STIM) are store-operated channel molecules that play essential roles in human physiology through a coupling mechanism of internal Ca(2+) store to Ca(2+) influx. However, the roles of ORAI and STIM in vascular endothelial cells under diabetic conditions remain unknown. Here, we investigated expression and signalling pathways of ORAI and STIM regulated by high glucose or hyperglycaemia using in vitro cell models, in vivo diabetic mice and tissues from patients. We found that ORAI1-3 and STIM1-2 were ubiquitously expressed in human vasculatures. Their expression was upregulated by chronic treatment with high glucose (HG, 25 mM D-glucose), which was accompanied by enhanced store-operated Ca(2+) influx in vascular endothelial cells. The increased expression was also observed in the aortae from genetically modified Akita diabetic mice (C57BL/6-Ins2(Akita)/J) and streptozocin-induced diabetic mice, and aortae from diabetic patients. HG-induced upregulation of ORAI and STIM genes was prevented by the calcineurin inhibitor cyclosporin A and NFATc3 siRNA. Additionally, in vivo treatment with the nuclear factor of activated T cells (NFAT) inhibitor A-285222 prevented the gene upregulation in Akita mice. However, HG had no direct effects on ORAI1-3 currents and the channel activation process through cytosolic STIM1 movement in the cells co-expressing STIM1-EYFP/ORAIs. We concluded that upregulation of STIM/ORAI through Ca(2+)-calcineurin-NFAT pathway is a novel mechanism causing abnormal Ca(2+) homeostasis and endothelial dysfunction under hyperglycaemia.
  
  
  CONCLUSIONS
  ORAI1-3 and STIM1-2 are ubiquitously expressed in vasculatures and upregulated by high glucose. Increased expression is confirmed in Akita (Ins2(Akita)/J) and STZ diabetic mice and patients. Upregulation mechanism is mediated by Ca(2+)/calcineurin/NFATc3 signalling. High glucose has no direct effects on ORAI1-3 channel activity and channel activation process.
authors.affiliation: Centre for Cardiovascular and Metabolic Research, Hull York Medical School, University of Hull, Hull, HU6 7RX, UK.
authors.forename: Nikoleta
authors.initials: N
authors.lastname: Daskoulidou
authors.forename: Bo
authors.initials: B
authors.lastname: Zeng
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Berglund
authors.forename: Hongni
authors.initials: H
authors.lastname: Jiang
authors.forename: Gui-Lan
authors.initials: GL
authors.lastname: Chen
authors.forename: Olga
authors.initials: O
authors.lastname: Kotova
authors.forename: Sunil
authors.initials: S
authors.lastname: Bhandari
authors.forename: James
authors.initials: J
authors.lastname: Ayoola
authors.forename: Steven
authors.initials: S
authors.lastname: Griffin
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Atkin
authors.forename: Maria F
authors.initials: MF
authors.lastname: Gomez
authors.forename: Shang-Zhong
authors.initials: SZ
authors.lastname: Xu
mesh_terms: D000818:Animals; D019703:Calcineurin / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D003921:Diabetes Mellitus, Experimental; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics / Q000378:metabolism; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000378:metabolism; D005786:Gene Expression Regulation; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D008875:Middle Aged; D050778:NFATC Transcription Factors / Q000378:metabolism*; D012333:RNA, Messenger; D015398:Signal Transduction; D015854:Up-Regulation
chemical_list: D015220:Calcium Channels; D050778:NFATC Transcription Factors; D012333:RNA, Messenger; D019703:Calcineurin; D005947:Glucose; D002118:Calcium