April 17, 2014

The endoplasmic reticulum and humans have quite a bit in common. Both are dynamic and constantly changing, but both also need something to ground and stabilize them. Maybe I’m reading too much into the beauty of the ER, but the image today is from a paper that only fuels my fascination.

The endoplasmic reticulum (ER) is a large, complex membrane-bound organelle that spreads throughout the cell and hosts the synthesis, folding, and sorting of membrane and secretory proteins. This network is dynamic and constantly rearranging, with diverse structural and functional domains. A recent paper describes the investigation into the role of the actin cytoskeleton in regulating ER sheet persistence and maintenance, which is important as the stationary domain of the ER. Joensuu and colleagues identified a subset of actin filaments associated with the ER, specifically to polygons defined by ER tubules and sheets. Actin depolymerization caused ER sheet fluctuation and resulted in a defective ER network. The actin motor myosin 1c also localizes to these actin filament arrays. In the images above, actin filament arrays (magenta, arrows) localize to the polygons (asterisks) associated with the ER (green).

Joensuu, M., Belevich, I., Ramo, O., Nevzorov, I., Vihinen, H., Puhka, M., Witkos, T., Lowe, M., Vartiainen, M., & Jokitalo, E. (2014). ER sheet persistence is coupled to myosin 1c-regulated dynamic actin filament arrays Molecular Biology of the Cell, 25 (7), 1111-1126 DOI: 10.1091/mbc.E13-12-0712