I am testing the theory that the endoplasmic reticulum, ER, is the circulatory network of the cell, connecting different organelles to each other, allowing them to share signals, lipids, and proteins.
I am particularly interested in how the cytoskeletal system of plants regulates the movement of the ER network. In interphase, the actinomyosin network drives movement of the ER, just as it drives the movement organelles through the cytoplasm in a process called cytoplasmic streaming, a phenomenon in plants, but not animal cells. Of the seventeen different myosin forms in plants, only six are involved in active cytoplasmic streaming. We are sorting out which of those six guide the different movements of the endoplasmic reticulum.
We have discovered that the ER interacts with the plasma membrane to transport sterols from outside of the cell to the nuclear envelope inside the cell. We are investigating how sterols move through the plant from their site of synthesis to their site of action. We hypothesize that ER-plasma membrane contact sites are required to get sterols out of their site of synthesis.
We have also discovered that a calcium signal is generated from the ER in response to photostimulation of the ER-chloroplast contact site with certain wavelengths of light. We are trying to figure out how this relates to signals that the chloroplast and ER send to the nucleus in response to these wavelengths of light.