title: Up-regulation of Orai1 expression and store operated Ca(2+) entry following activation of membrane androgen receptors in MCF-7 breast tumor cells.
abstract: BACKGROUND
  Membrane androgen receptors (mAR) are functionally expressed in a variety of tumor-cells including the breast tumor-cell line MCF-7. They are specifically activated by testosterone albumin conjugates (TAC). The mAR sensitive signaling includes activation of Ras-related C3 botulinum toxin substrate 1 (Rac1) and reorganization of the actin filament network. Signaling of tumor-cells may further involve up-regulation of pore forming Ca(2+) channel protein Orai1, which accomplishes store operated Ca(2+) entry (SOCE). This study explored the regulation of Orai1 abundance and SOCE by mAR.
  
  
  METHODS
  Actin filaments were visualized utilizing confocal microscopy, Rac1 activity using GST-GBD assay, Orai1 transcript levels by RT-PCR and total protein abundance by western blotting, Orai1 abundance at the cell surface by confocal microscopy and FACS-analysis, cytosolic Ca(2+) activity ([Ca(2+)]i) utilizing Fura-2-fluorescence, and SOCE from increase of [Ca(2+)]i following readdition of Ca(2+) after store depletion with thapsigargin (1 μM).
  
  
  RESULTS
  TAC treatment of MCF-7 cells was followed by Rac1 activation, actin polymerization, transient increase of Orai1transcript levels and protein abundance, and transient increase of SOCE. The transient increase of Orai1 protein abundance was abrogated by Rac1 inhibitor NSC23766 (50 μM) and by prevention of actin reorganization with cytochalasin B (1 μM).
  
  
  CONCLUSIONS
  mAR sensitive Rac1 activation and actin reorganization contribute to the regulation of Orai1 protein abundance and SOCE.
authors.affiliation: Department of Physiology, University of Tuebingen, Tuebingen, Germany. guilailiu1986@gmail.com.
authors.forename: Guilai
authors.initials: G
authors.lastname: Liu
authors.affiliation: Department of Physiology, University of Tuebingen, Tuebingen, Germany. honisch.s@gmx.de.
authors.forename: Sabina
authors.initials: S
authors.lastname: Honisch
authors.affiliation: Department of Physiology, University of Tuebingen, Tuebingen, Germany. liugx3692000@gmail.com.
authors.forename: Guoxing
authors.initials: G
authors.lastname: Liu
authors.affiliation: Department of Physiology, University of Tuebingen, Tuebingen, Germany. sebastian.schmidt@medizin.uni-tuebingen.de.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Schmidt
authors.affiliation: Department of Biochemistry, University of Crete Medical School, Heraklion, Crete, Greece. sksa7@hotmail.com.|Department of Zoology, Science College, King Saud University, Riyadh, Saudi Arabia. sksa7@hotmail.com.
authors.forename: Saad
authors.initials: S
authors.lastname: Alkahtani
authors.affiliation: Department of Zoology, Science College, King Saud University, Riyadh, Saudi Arabia. alkah11@yahoo.com.
authors.forename: Abdullah A
authors.initials: AA
authors.lastname: AlKahtane
authors.affiliation: Department of Physiology, University of Tuebingen, Tuebingen, Germany. cstourn@med.uoc.gr.|Department of Biochemistry, University of Crete Medical School, Heraklion, Crete, Greece. cstourn@med.uoc.gr.
authors.forename: Christos
authors.initials: C
authors.lastname: Stournaras
authors.affiliation: Department of Physiology, University of Tuebingen, Tuebingen, Germany. florian.lang@uni-tuebingen.de.|Physiologisches Institut, der Universität Tübingen, Gmelinstr. 5, D-72076, Tübingen, Germany. florian.lang@uni-tuebingen.de.
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
mesh_terms: D008841:Actin Cytoskeleton / Q000502:physiology; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000378:metabolism* / Q000503:physiopathology; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D061986:MCF-7 Cells; D000071740:ORAI1 Protein; D060888:Real-Time Polymerase Chain Reaction; D011944:Receptors, Androgen / Q000502:physiology*; D019284:Thapsigargin / Q000494:pharmacology; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
chemical_list: D015220:Calcium Channels; D004791:Enzyme Inhibitors; D000071740:ORAI1 Protein; C510746:ORAI1 protein, human; C107953:RAC1 protein, human; D011944:Receptors, Androgen; D019284:Thapsigargin; D020830:rac1 GTP-Binding Protein; D002118:Calcium