The Role of Bestrophin-1 in Intracellular Ca2+ Signaling

  • Olaf Strauß
  • Claudia Müller
  • Nadine Reichhart
  • Ernst R. Tamm
  • Nestor Mas Gomez
Conference paper
Part of the Advances in Experimental Medicine and Biology book series (volume 801)


Mutations in the BEST1 gene lead to a variety of retinal degenerations, among them Best’s vitelliforme macular degeneration. To clarify the mechanism of the disease, the understanding of the function of BEST1 gene product, bestrophin-1, is mandatory. In overexpression studies bestrophin-1 appeared to function as a Ca2+-dependent Cl channel. On the other hand, bestrophin-1 is able to participate in intracellular Ca2+ signaling. Endogenously expressed bestrophin-1 largely localized to the cytosolic compartment close to the basolateral membrane of the retinal pigment epithelium (RPE) as it can be shown using differential centrifugation, immunohistochemistry, and transmission electron microscopy. To elucidate a cytosolic function of bestrophin-1, we explored the store-operated Ca2+ entry in short-time cultured porcine RPE cells. Depletion of cytosolic Ca2+stores by SERCA inhibition led to activation of Orai-1 Ca2+ channels. This resulted in an influx of extracellular Ca2+ into the cell which was reduced when bestrophin-1 expression was knocked down using siRNA techniques. Quantification of Ca2+ which can be released from cytosolic Ca2+ stores revealed that after reduction of bestrophin-1 expression less Ca2+ is stored in ER Ca2+ stores. Thus, bestrophin-1 functions as an intracellular Cl channel which helps to accumulate and to release Ca2+ from stores by conducting the counterion for Ca2+.


Bestrophin-1 Stim-1 Orai-1 Ca2+-signaling Store-operated Ca2+ entry 


  1. 1.
    Petrukhin K, Koisti MJ, Bakall B, Li W, Xie G, Marknell T et al (1998) Identification of the gene responsible for best macular dystrophy. Nat Genet 19(3):241–247PubMedCrossRefGoogle Scholar
  2. 2.
    Marquardt A, Stohr H, Passmore LA, Kramer F, Rivera A, Weber BH (1998) Mutations in a novel gene, VMD2, encoding a protein of unknown properties cause juvenile-onset vitelliform macular dystrophy (Best’s disease). Hum Mol Genet 7(9):1517–1525PubMedCrossRefGoogle Scholar
  3. 3.
    Hartzell HC, Qu Z, Yu K, Xiao Q, Chien LT (2008) Molecular physiology of bestrophins: multifunctional membrane proteins linked to best disease and other retinopathies. Physiol Rev 88(2):639–672PubMedCrossRefGoogle Scholar
  4. 4.
    Marmorstein AD, Cross HE, Peachey NS (2009) Functional roles of bestrophins in ocular epithelia. Prog Retin Eye Res 28(3):206–226PubMedCentralPubMedCrossRefGoogle Scholar
  5. 5.
    Boon CJ, Klevering BJ, Leroy BP, Hoyng CB, Keunen JE, den Hollander AI (2009) The spectrum of ocular phenotypes caused by mutations in the BEST1 gene. Prog Retin Eye Res 28(3):187–205PubMedCrossRefGoogle Scholar
  6. 6.
    Xiao Q, Hartzell HC, Yu K (2010) Bestrophins and retinopathies. Pflugers Arch 460(2):559–569PubMedCentralPubMedCrossRefGoogle Scholar
  7. 7.
    Planells-Cases R, Jentsch TJ (2009) Chloride channelopathies. Biochim Biophys Acta 1792(3):173–189PubMedCrossRefGoogle Scholar
  8. 8.
    White K, Marquardt A, Weber BH (2000) VMD2 mutations in vitelliform macular dystrophy (Best disease) and other maculopathies. Hum Mutat 15(4):301–308PubMedCrossRefGoogle Scholar
  9. 9.
    Milenkovic VM, Rivera A, Horling F, Weber BH (2007) Insertion and topology of normal and mutant bestrophin-1 in the endoplasmic reticulum membrane. J Biol Chem 282(2):1313–1321PubMedCrossRefGoogle Scholar
  10. 10.
    Marmorstein AD, Marmorstein LY, Rayborn M, Wang X, Hollyfield JG, Petrukhin K (2000) Bestrophin the product of the Best vitelliform macular dystrophy gene (VMD2), localizes to the basolateral plasma membrane of the retinal pigment epithelium. Proc Natl Acad Sci USA 97(23):12758–12763PubMedCentralPubMedCrossRefGoogle Scholar
  11. 11.
    Neussert R, Muller C, Milenkovic VM, Strauss O (2010) The presence of bestrophin-1 modulates the Ca2+ recruitment from Ca2+ stores in the ER. Pflugers Arch 460(1):163–175PubMedCrossRefGoogle Scholar
  12. 12.
    Reichhart N, Milenkovic VM, Halsband CA, Cordeiro S, Strauss O (2010) Effect of bestrophin-1 on L-type Ca(2+) channel activity depends on the Ca(2+) channel beta-subunit. Exp Eye Res 91(5):630–639PubMedCrossRefGoogle Scholar
  13. 13.
    Sun H, Tsunenari T, Yau KW, Nathans J (2002) The vitelliform macular dystrophy protein defines a new family of chloride channels. Proc Natl Acad Sci USA 99(6):4008–4013PubMedCentralPubMedCrossRefGoogle Scholar
  14. 14.
    Hartzell C, Putzier I, Arreola J (2005) Calcium-activated chloride channels. Annu Rev Physiol 67:719–758PubMedCrossRefGoogle Scholar
  15. 15.
    Fischmeister R, Hartzell HC (2005) Volume sensitivity of the bestrophin family of chloride channels. J Physiol 562(Pt 2):477–491PubMedCentralPubMedCrossRefGoogle Scholar
  16. 16.
    Xiao Q, Yu K, Cui YY, Hartzell HC (2009) Dysregulation of human bestrophin-1 by ceramide-induced dephosphorylation. J Physiol 587(Pt 18):4379–4391PubMedCentralPubMedCrossRefGoogle Scholar
  17. 17.
    Marchant D, Yu K, Bigot K, Roche O, Germain A, Bonneau D et al (2007) New VMD2 gene mutations identified in patients affected by Best vitelliform macular dystrophy. J Med Genet 44(3):e70PubMedCentralPubMedCrossRefGoogle Scholar
  18. 18.
    Yu K, Cui Y, Hartzell HC (2006) The bestrophin mutation A243V, linked to adult-onset vitelliform macular dystrophy, impairs its chloride channel function. Invest Ophthalmol Vis Sci 47(11):4956–4961PubMedCrossRefGoogle Scholar
  19. 19.
    Qu Z, Hartzell HC (2008) Bestrophin Cl− channels are highly permeable to HCO3−. Am J Physiol Cell Physiol 294(6):C1371–C1377PubMedCentralPubMedCrossRefGoogle Scholar
  20. 20.
    Chien LT, Hartzell HC (2008) Rescue of volume-regulated anion current by bestrophin mutants with altered charge selectivity. J Gen Physiol 132(5):537–546PubMedCentralPubMedCrossRefGoogle Scholar
  21. 21.
    Rosenthal R, Heimann H, Agostini H, Martin G, Hansen LL, Strauss O (2007) Ca2+ channels in retinal pigment epithelial cells regulate vascular endothelial growth factor secretion rates in health and disease. Mol Vis 13:443–456PubMedCentralPubMedGoogle Scholar
  22. 22.
    Milenkovic VM, Krejcova S, Reichhart N, Wagner A, Strauss O (2011) Interaction of bestrophin-1 and Ca2+ channel β-subunits: identification of new binding domains on the bestrophin-1  C-terminus. PLoS One; in revisionGoogle Scholar
  23. 23.
    Yu K, Xiao Q, Cui G, Lee A, Hartzell HC (2008) The best disease-linked Cl− channel hBest1 regulates Ca V 1 (L-type) Ca2+ channels via src-homology-binding domains. J Neurosci 28(22):5660–5670PubMedCentralPubMedCrossRefGoogle Scholar
  24. 24.
    Burgess R, Millar ID, Leroy BP, Urquhart JE, Fearon IM, De Baere E et al (2008) Biallelic mutation of BEST1 causes a distinct retinopathy in humans. Am J Hum Genet 82(1):19–31PubMedCentralPubMedCrossRefGoogle Scholar
  25. 25.
    Davidson AE, Millar ID, Urquhart JE, Burgess-Mullan R, Shweikh Y, Parry N et al (2009) Missense mutations in a retinal pigment epithelium protein, bestrophin-1, cause retinitis pigmentosa. Am J Hum Genet 85(5):581–592PubMedCentralPubMedCrossRefGoogle Scholar
  26. 26.
    Milenkovic VM, Roehrl E, Weber BH, Strauss O (2011) Disease-associated missense mutations in bestrophin-1 affect cellular trafficking and anion conductance. J Cell Sci (submitted)Google Scholar
  27. 27.
    Marmorstein LY, Wu J, McLaughlin P, Yocom J, Karl MO, Neussert R et al (2006) The light peak of the electroretinogram is dependent on voltage-gated calcium channels and antagonized by bestrophin (best-1). J Gen Physiol 127(5):577–589PubMedCentralPubMedCrossRefGoogle Scholar
  28. 28.
    Zhang Y, Stanton JB, Wu J, Yu K, Hartzell HC, Peachey NS et al (2010) Suppression of Ca2+ signaling in a mouse model of Best disease. Hum Mol Genet 19(6):1108–1118PubMedCentralPubMedCrossRefGoogle Scholar
  29. 29.
    Barro-Soria R, Aldehni F, Almaca J, Witzgall R, Schreiber R, Kunzelmann K (2010) ER-localized bestrophin 1 activates Ca2+-dependent ion channels TMEM16A and SK4 possibly by acting as a counterion channel. Pflugers Arch 459(3):485–497PubMedCrossRefGoogle Scholar
  30. 30.
    Putney JW Jr (2005) Capacitative calcium entry: sensing the calcium stores. J Cell Biol 169(3):381–382PubMedCentralPubMedCrossRefGoogle Scholar
  31. 31.
    Mas Gomez N, Tamm ER, Strauss O (2012) Involvement of bestrophin-1 in store-operated calcium entry in porcine retinal pigment epithelium. Pflugers Arch (Dec.4, Epub ahead of print)Google Scholar
  32. 32.
    Kunzelmann K, Kongsuphol P, Aldehni F, Tian Y, Ousingsawat J, Warth R et al (2009) Bestrophin and TMEM16-Ca(2+) activated Cl(−) channels with different functions. Cell Calcium 46(4):233–241PubMedCrossRefGoogle Scholar
  33. 33.
    Strauss O (2005) Retinal pigment epithelium in visual function. Physiol Rev 85(3):845–881PubMedCrossRefGoogle Scholar
  34. 34.
    Wimmers S, Karl MO, Strauss O (2007) Ion channels in the RPE. Prog Retin Eye Res 26(3):263–301PubMedCrossRefGoogle Scholar
  35. 35.
    Maminishkis A, Jalickee S, Blaug SA, Rymer J, Yerxa BR, Peterson WM et al (2002) The P2Y(2) receptor agonist INS37217 stimulates RPE fluid transport in vitro and retinal reattachment in rat. Invest Ophthalmol Vis Sci 43(11):3555–3566PubMedGoogle Scholar
  36. 36.
    Mitchell CH (2001) Release of ATP by a human retinal pigment epithelial cell line: potential for autocrine stimulation through subretinal space. J Physiol 534(Pt 1):193–202PubMedCentralPubMedCrossRefGoogle Scholar
  37. 37.
    Peterson WM, Meggyesy C, Yu K, Miller SS (1997) Extracellular ATP activates calcium signaling, ion, and fluid transport in retinal pigment epithelium. J Neurosci 17(7):2324–2337PubMedGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2014

Authors and Affiliations

  • Olaf Strauß
    • 1
    • 2
  • Claudia Müller
    • 2
  • Nadine Reichhart
    • 1
    • 2
  • Ernst R. Tamm
    • 3
  • Nestor Mas Gomez
    • 2
    • 4
  1. 1.Experimental Ophthalmology, Department of OphthalmologyCharite University Medicine BerlinBerlinGermany
  2. 2.Experimental Ophthalmology, Eye HospitalUniversity Medical Center RegensburgRegensburgGermany
  3. 3.Institute of Human Anatomy and EmbryologyUniversity of Regensburg,RegensburgGermany
  4. 4.Department of Clinical Studies, School of Veterinary MedicineUniversity of PennsylvaniaPhiladelphiaUSA

Personalised recommendations