Interactions between the rough endoplasmic reticulum and the nuclear membrane during increased proliferation of the endoplasmic reticulum.

Flickinger (1978) has shown conclusively that when there is demand for membrane by the nucleus, such as during repair of a damaged nuclear envelope, several membrane continuities develop between the RER and the nuclear envelope. This experiment was set up to determine if reversal of flow of membrane from the nuclear envelope to the RER would occur during phenobarbital-stimulated increased synthesis of RER. During the increased synthesis of RER following the stimulation of liver cells, it was observed that there was increase in the number of membrane continuities between the RER and the nuclear envelope. Increased blebbing and vesicle formation from the nuclear envelope was also seen. These vesicles were liberated as RER into the cytoplasm. It is therefore suggested that the nuclear envelope and the RER are in a state of equilibrium (RER in equilibrium NE) and membrane can be transferred either way depending on demand through the many membrane continuities that develop between the two organelles.