Is cholesterol bad for mitochondria?


by Sayuri Miyamoto

Cholesterol is an important component of cell membranes and plays essential structural and signaling roles. It is synthesized in the endoplasmic reticulum and distributed to other cell membranes/compartments through a tightly regulated trafficking system involving vesicular and non-vesicular processes [1]. Cholesterol distribution among intra-cellular membranes is not homogeneous. Mitochondria are cholesterol-poor organelles (less than 5 %). However, mitochondrial cholesterol is increased in cancer cell lines and treatment of these cells with statins (cholesterol lowering drugs) increases their susceptibility to chemotherapy [2].

How mitochondrial cholesterol could influence


A novel ubiquitin-related marker in oxidative stress response

by Marilene Demasi

Protein polyubiquitination was first described as a post-translational modification to direct proteins for degradation. The ubiquitin molecule is covalently bound to the target protein and the polyubiquitin chain is created by successive attachments of ubiquitin through its carboxy-terminal Glycine mainly to Lysine48 (K48) residues of previously conjugated ubiquitin. Proteins tagged with a K48-linked polyubiquitin chain are directed for degradation. However, distinct ubiquitin chains are built up through other Lysine residues from ubiquitin, resulting in distinct structural patterns of ubiquitin complexes, which in most cases are unrelated to target protein degradation.