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Prix Alexandre Joannidès 2014 Académie des sciences : Irwin DAVIDSON
The protein SET plays a key role in DNA repair and inhibits excessive DNA recombination by controlling chromatin structure through its interaction with the proteins KAP1 and HP1.
March 26, 2015
The team of Evi Soutoglou at IGBMC discovered the protein SET as a novel player in repair of lesions occurring at both strands of DNA. They showed that SET inhibits excessive DNA repair by recombination by controlling chromatin structure through its interaction with the proteins KAP1 and HP1. Cancerous cells where SET is over abundant have decreased capacity to repair DNA lesions and they are sensitive to chemotherapeutic agents, like derivatives of camptothecin.
These results are published March 26, 2015 in Cell Reports.
Allele-specific analysis of SNP6, Exome-seq, ChIP-seq and RNA-seq led to the identification of genes escaping X chromosome inactivation in breast cancer cells and to the characterization of the corresponding chromatin states.
March 16, 2015
A collaborative study between the teams of Edith Heard, Marc-Henri Stern and Anne Vincent-Salomon at the Curie Institute and the team of Hinrich Gronemeyer at the IGBMC has now revealed major epigenetic instability of the inactive X chromosome in breast cancer. They also demonstrated that certain genes escape from X inactivation and perturb dosage of X-linked factors, which may contribute to tumorigenesis and/or disease progression. These results are published on February 4th 2015 in Genome Research.
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.
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.