IGBMC : Institut de la Génétique et de la Biologie Moléculaire et Cellulaire

The international team coordinated by Imre Berger (EMBL) and Làszlò Tora (IGBMC) just demonstrated that the TFIID transcription factor, which controls the gene transcription in eukaryote cells, starts to assemble in building blocks in the cytoplasm before penetrating into the nucleus.

These results - published January 14, 2015 in Nature Communications - open up a new way for research on gene regulation and defects during transcription.

Roméo RICCI's team at the IGBMC recently demonstrated that the pancreatic beta cell, responsible for proper insulin secretion, responds in a very distinct way to nutrient withdrawal. The beta cell, in contrast to most other cells, does not digest its own cellular structures (a process known as autophagy) to generate its own nutrients when they are not available from the environment. Instead, autophagy is actively suppressed and replaced through a newly discovered process in beta cells, the specific digestion of freshly made insulin granules. While this cellular process is an important adaptation to fasting, its deregulation may contribute to type 2 diabetes.

This discovery in beta cells may thus open new therapeutic perspectives in the treatment of diabetic patients. This work is published on February 20th 2015 in Science Magazine.

Having identified precisely how vitamin D binds to its receptor, a study coordinated by Natacha Rochel and Dino Moras (Department of Integrated Structural Biology, IGBMC) and Daniel Metzger (Department of Functional Genomics and Cancer, IGBMC) explains the severe skeletal defects of patients carrying mutations of this receptor and osteoporosis due to vitamin D deficiency.

The researchers indeed showed that the absence of Vitamin D binding to its receptor leads to a more severe calcium deficiency than in the absence of receptor. Their results, published on January 22nd 2015 in Cell Reports, also pave a way to identify Vitamin D analogs for the treatment of various pathologies like osteoporosis, neuro-degenerative and autoimmune diseases, as well as cancer.

The mitochondrial iron accumulation observed in Friedreich’s ataxia was thought to be noxious. Hélène PUCCIO's team at the IGBMC has just demonstrated that this accumulation rather allows to partially compensate for the absence of frataxin. Resulting of a modification of the IRP1 protein activity, this accumulation supports the biogenesis of iron-sulfur clusters (Fe-S) and heme in mitochondria.

These important results regarding the cellular adaptation in the absence of frataxin also question the validity of therapeutic approaches aiming at neutralizing the cellular iron accumulation observed in Friedreich’s ataxia.

This work is published in Cell Metabolism on February 3rd, 2015.