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Bidirectional Ca(2+) signaling occurs between the endoplasmic reticulum and acidic organelles
The endoplasmic reticulum (ER) and acidic organelles (endo-lysosomes) act as separate Ca(2+) stores that release Ca(2+) in response to the second messengers IP(3) and cADPR (ER) or NAADP (acidic organelles). Typically, trigger Ca(2+) released from acidic organelles by NAADP subsequently recruits IP(...
Autores principales: | , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
The Rockefeller University Press
2013
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3601362/ https://www.ncbi.nlm.nih.gov/pubmed/23479744 http://dx.doi.org/10.1083/jcb.201204078 |
Sumario: | The endoplasmic reticulum (ER) and acidic organelles (endo-lysosomes) act as separate Ca(2+) stores that release Ca(2+) in response to the second messengers IP(3) and cADPR (ER) or NAADP (acidic organelles). Typically, trigger Ca(2+) released from acidic organelles by NAADP subsequently recruits IP(3) or ryanodine receptors on the ER, an anterograde signal important for amplification and Ca(2+) oscillations/waves. We therefore investigated whether the ER can signal back to acidic organelles, using organelle pH as a reporter of NAADP action. We show that Ca(2+) released from the ER can activate the NAADP pathway in two ways: first, by stimulating Ca(2+)-dependent NAADP synthesis; second, by activating NAADP-regulated channels. Moreover, the differential effects of EGTA and BAPTA (slow and fast Ca(2+) chelators, respectively) suggest that the acidic organelles are preferentially activated by local microdomains of high Ca(2+) at junctions between the ER and acidic organelles. Bidirectional organelle communication may have wider implications for endo-lysosomal function as well as the generation of Ca(2+) oscillations and waves. |
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