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Prix Alexandre Joannidès 2014 Académie des sciences : Irwin DAVIDSON
The TAF2-TAF8-TAF10 complex forms in the cytoplasm before it enters into the nucleus of the cell and joins TFIID-precursor.
Jan. 14, 2015
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.
The Vitamin D receptor (VDR) activates numerous genes following binding of bioactive vitamin D (calcitriol, A).
Gemini analog bound to the mutated receptor VDRgem have similar effects (B).
On the other hand, VDRgem cannot bind calcitriol (C). This induces a repression of numerous genes and leads to rickets that are more severe than in the absence of the receptor.
Jan. 22, 2015
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.
Upon PKD activation (A), insulin granules generated at the Golgi of pancreatic beta cells are released at the plasma membrane (in yellow in the scheme and in the electron microscopy picture). Upon fasting, PKD1 gets inactivated (B) and insulin granules fuse with lysosomes (in purple) that contain enzymes required for degradation of insulin : in parallel activation of mTOR suppresses autophagy.
Feb. 20, 2015
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.
Dec. 28, 2014
The Integrated Structural Biology (ISB) department of IGBMC is recruiting new group leaders with support from the Laboratory of Excellence (LabEx) initiative.
Research teams in the department address fundamental biological questions of major importance for human health and diseases, mainly in the field of eukaryotic gene expression at the transcriptional level (basal transcriptional machinery, transcriptional activators and co-regulators, histone modifiers, chromatin structure, DNA topology, epigenetics) and at the translational level (RNA stability, protein synthesis, ribosome structure).
Our aim is to unveil the 3D structure of macromolecular complexes and understanding its relationship to invivo functions via an integrated multi-scale approach.
To strengthen and expand its research, the ISB department welcomes applications for team leader positions.
In normal cells (A), iron import (through transferrin and its receptor) is sufficient to support the production of heme and iron-sulfur (Fe-S) clusters. The energy supplied to the cell is thus sufficient and most IRP1 proteins contain an Fe-S cluster.
In the absence of frataxin (B), the productions of heme and Fe-S clusters are less efficient. IRP1 devoid of Fe-S cluster then activates cellular iron import to support mitochondrial iron needs. Frataxin-deficient cells have less energy than a normal cell, but iron accumulation act as a compensatory mechanism that aims at increasing heme and Fe-S cluster productions.
Feb. 4, 2015
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.