As advances in cell biology deepen our understanding of cellular functions, a new study published in The EMBO Journal has propelled forward our knowledge of calcium signaling, highlighting the significance of a protein known as Anoctamin 8 (ANO8) in the tethering of endoplasmic reticulum (ER) and plasma membrane (PM) for calcium assembly. This finding represents a significant leap in our comprehension of how cells manage inter-membrane communication and calcium signaling, cornerstones in the orchestration of cellular activities.
According to the research team, helmed by Archana Jha, Laura Vachel, Woo Young Chung, Sarah Lake, Guofeng Zhang, Malini Ahuja, and Shmuel Muallem from the National Institute of Dental and Craniofacial Research (NIDCR) at the National Institutes of Health (NIH), and Jozsef Maleth from the University of Szeged, the tethering of the ER to the PM at ER/PM junctions establishes a pivotal point for the assembly of calcium signaling complexes. The role of ANO8 at these junctions suggests that this protein may be a key target for therapeutic interventions in conditions and diseases related to dysfunctional calcium signaling [1].
The Pivotal Role of ANO8 in Calcium Signaling
Calcium ions (Ca^2+) play a crucial role in various cellular processes, from muscle contractions and neurotransmitter release to cell growth and death. At the heart of calcium signaling are the ER/PM junctions, where the ER Ca^2+ release and PM Ca^2+ influx are tightly coordinated [5]. The study’s findings position ANO8 as a novel and essential anchor, residing at these junctions and engaging in the assembly of multiprotein complexes that handle calcium signaling, including ORAI1 and STIM1, key components in the maintenance of calcium homeostasis.
This study represents a considerable advancement from previous investigations into ER/PM junctions, which have already identified these sites as crucial for lipid homeostasis and inter-organelle communication [10, 19]. Anoctamins are known to be a family of proteins contributing various functions in cells, including ion transport and phospholipid scrambling [32]. ANO8, part of this family, has now been characterized as a tethering molecule and its interaction with ER and PM underscores its broader role in cellular signaling.
Advanced Research Methods and Implications
The research employed state-of-the-art live-cell fluorescence resonance energy transfer (FRET) microscopy and other biochemical approaches to analyze the interaction between ANO8 and the key players in calcium signaling pathways. Muallem and colleagues’ rigorous approach, including genetic strategies for manipulating ANO8 and calcium imaging to monitor the dynamics of calcium signaling, provided insights into the mechanisms of ER/PM tethering.
The findings could impact fields ranging from neurobiology, where calcium signaling is crucial for neuronal function, to endocrinology, addressing dysfunctions in secretion caused by impaired calcium signaling. Furthermore, the insights into ANO8 could open avenues for novel treatments targeting diseases such as cystic fibrosis, hypertension, and certain forms of cancer, all of which involve disruptions in calcium homeostasis.
DOI and References
DOI: 10.15252/embj.2018101452 [1]
References
1. Ahuja, M., Jha, A., Maleth, J., Park, S., & Muallem, S. (2014). cAMP and Ca^2+ signaling in secretory epithelia: crosstalk and synergism. Cell Calcium, 55(6), 385-393. DOI: 10.1016/j.ceca.2014.02.014 [PMC4058382]
2. Berridge, M. J. (2016). The inositol trisphosphate/calcium signaling pathway in health and disease. Physiological Reviews, 96(4), 1261-1296. DOI: 10.1152/physrev.00006.2016 [27512009]
3. Henne, W. M., Liou, J., & Emr, S. D. (2015). Molecular mechanisms of inter-organelle ER-PM contact sites. Current Opinion in Cell Biology, 35, 123-130. DOI: 10.1016/j.ceb.2015.04.006 [26025028]
4. Hong, J. H., Li, Q., Kim, M. S., Shin, D. M., Feske, S., Birnbaumer, L., Cheng, K. T., & Ambudkar, I. S. (2011). Polarized but differential localization and recruitment of STIM1, Orai1 and TRPC channels in secretory cells. Traffic, 12(2), 232-245. DOI: 10.1111/j.1600-0854.2010.01136.x [PMC3021582]
5. Prakriya, M., & Lewis, R. S. (2015). Store-operated calcium channels. Physiological Reviews, 95(4), 1383-1436. DOI: 10.1152/physrev.00020.2014 [PMC4600950]
Keywords
1. Anoctamin 8 in Calcium Signaling
2. ER-PM Junctions
3. Intracellular Calcium Homeostasis
4. Tethering of ER to PM
5. Anoctamins Function in Cells
Conclusion
The study’s revelations concerning ANO8 and calcium signaling provide a stepping stone for future research into therapeutic targets for diseases related to calcium signaling impairments. The discovery of the role of ANO8 in ER/PM tethering and its mechanistic underpinnings advances our understanding in the field of cell biology, with potentially significant clinical ramifications. Further exploration into ANO8 and its partners may yield innovative strategies to manipulate calcium signaling in disease, signifying a promising direction for biomedical research and therapeutic development.