Divide et impera: the dictum of peroxisomes.

Peroxisomes are unique organelles which display properties of autonomous organelles, as they can multiply by fission of pre-existing ones. Peroxisomes, however, can also develop from the endoplasmic reticulum (ER). This process has convincingly been shown in peroxisome-deficient yeast cells, upon reintroduction of the corresponding gene. Whether peroxisomes also are formed from the ER in wild-type cells that contain peroxisomes is still under debate. Also, the existence of vesicular transport pathways between peroxisomes and the ER is still unresolved. Several new proteins and pathways that play a role in peroxisome proliferation have been identified in the last few years. A surprising finding was that proteins well known for their function in mitochondrial fission (Fis1, Dnm1) are responsible for peroxisome fission as well. In this contribution we discuss recent advancements in research on peroxisome proliferation.