Mouse mammary tumor virus in human breast cancer red herring or smoking gun?

This Commentary highlights the article by Mazzanti et al (in this issue), expounding on the detection of MMTV-like nucleic acid sequences in human pre-invasive breast cancer tissue.

Rab32 modulates apoptosis onset and mitochondria-associated membrane (MAM) properties.

The mitochondria-associated membrane (MAM) has emerged as an endoplasmic reticulum (ER) signaling hub that accommodates ER chaperones, including the lectin calnexin. At the MAM, these chaperones control ER homeostasis but also play a role in the onset of ER stress-mediated apoptosis, likely through the modulation of ER calcium signaling. These opposing roles of MAM-localized chaperones suggest the existence of mechanisms that regulate the composition and the properties of ER membrane domains.

Ero1alpha requires oxidizing and normoxic conditions to localize to the mitochondria-associated membrane (MAM).

Protein secretion from the endoplasmic reticulum (ER) requires the enzymatic activity of chaperones and oxidoreductases that fold polypeptides and form disulfide bonds within newly synthesized proteins. The best-characterized ER redox relay depends on the transfer of oxidizing equivalents from molecular oxygen through ER oxidoreductin 1 (Ero1) and protein disulfide isomerase to nascent polypeptides. The formation of disulfide bonds is, however, not the sole function of ER oxidoreductases, which are also important regulators of ER calcium homeostasis.