STIM1 and STIM2 behave differently in neurons during store operated calcium entry

• Autorzy: Gruszczynska-Biegala J. , Pomorski P. , Kuznicki J.
• Języki publikacji: EN

Abstrakty

EN

Store Operated Calcium Entry (SOCE) is a common phenomenon in non-excitable cells. The process relies on extracellular calcium influx through the plasma membrane (PM) channels, tightly regulated by endoplasmic reticulum (ER) calcium concentration. This influx allows refilling of the ER after Ca2+ release to the cytoplasm. The proteins involved in this process are calcium sensors STIM1 and STIM2 (located in ER), and calcium channel forming protein called ORAI1 (located in PM). Complexes of the STIM proteins with ORAI1 were identified in the fluorescent microscopy and called \”puncta\”. In neurons the molecular mechanism of SOCE is unclear. Our previous research led to the identification and characterization of STIM1 in the brain and neurons (Acta Neurobiol. Exp. 2009, 69:413-28; Neurochem. Int. 2009, 54:49-55). In this study we found that also STIM2 is expressed in neurons and aimed our work to compare the function of STIM proteins. In cultured cortical neurons, overexpressing YFP-STIM1/YFP-STIM2 and ORAI1, we observed changes of the fluorescence distribution from dispersed before to aggregated complexes of STIM1-ORAI1 and STIM2-ORAI1 after treatment with thapsigargin (TG). We also found that depletion of calcium from ER increased the number of STIM1-ORAI1 puncta much more than of STIM2-ORAI1 puncta. Then we analyzed the effects of STIM1/ORAI1 or STIM2/ORAI1 expression on intracellular calcium level during SOCE using Ca2+ imaging in two types of experiments. The first one was an analysis of SOCE after depletion of intracellular Ca2+ stores by TG and subsequent incubation of cells in 2 mM Ca2+ media. These measurements were performed also in the presence of SOCE inhibitors (ML-9 or 2-APB). SOCE was enhanced in neurons transfected with STIM1/ORAI1, but not with STIM2/ORAI1. Moreover, both inhibitors reduced calcium influx by about 70% in neurons expressing STIM1/ORAI1, while produced no significant change in neurons transfected with STIM2/ ORAI1. In the second type of experiments a removal of extracellular Ca2+ caused a sustained decrease in intracellular calcium in all experimental setups, however the highest decrease was observed in neurons transfected with STIM2/ORAI1. In store-repleted cells, an increase in constitutive Ca2+ entry was observed with STIM1/ ORAI1 and STIM2/ORAI1 expression, but not with STIM expression alone. STIM2/ORAI1-mediated constitutive Ca2+ level was raised by 50 µM 2-APB, but not in case of STIM1/ORAI1 transfectants. Based on these observations we suggest that in neurons STIM1 and STIM2 proteins have distinct role in SOCE.

• Wydawca: -
• Czasopismo: Acta Neurobiologiae Experimentalis
• Rocznik: 2011
• Tom: 71
• Numer: 1
• Opis fizyczny: p.160-161

Twórcy

autor

Gruszczynska-Biegala J.

• International Institute of Molecular and Cell Biology, Warsaw, Poland

autor

Pomorski P.

• Nencki Institute of Experimental Biology, Warsaw, Poland

autor

Kuznicki J.

• International Institute of Molecular and Cell Biology, Warsaw, Poland
• Nencki Institute of Experimental Biology, Warsaw, Poland