The Experts below are selected from a list of 79830 Experts worldwide ranked by ideXlab platform
Ulrich Rass - One of the best experts on this subject based on the ideXlab platform.
-
Rif1 S-acylation mediates DNA double-strand break repair at the inner Nuclear Membrane.
Nature Communications, 2019Co-Authors: Gabriele A. Fontana, Julia K. Reinert, Stefano Mattarocci, Benoît Falquet, Dominique Klein, Nicolas H. Thomä, David Shore, Daniel Heß, Ulrich RassAbstract:Rif1 is involved in telomere homeostasis, DNA replication timing, and DNA double-strand break (DSB) repair pathway choice from yeast to human. The molecular mechanisms that enable Rif1 to fulfill its diverse roles remain to be determined. Here, we demonstrate that Rif1 is S-acylated within its conserved N-terminal domain at cysteine residues C466 and C473 by the DHHC family palmitoyl acyltransferase Pfa4. Rif1 S-acylation facilitates the accumulation of Rif1 at DSBs, the attenuation of DNA end-resection, and DSB repair by non-homologous end-joining (NHEJ). These findings identify S-acylation as a posttranslational modification regulating DNA repair. S-acylated Rif1 mounts a localized DNA-damage response proximal to the inner Nuclear Membrane, revealing a mechanism of compartmentalized DSB repair pathway choice by sequestration of a fatty acylated repair factor at the inner Nuclear Membrane.
Howard J Worman - One of the best experts on this subject based on the ideXlab platform.
-
proteasome mediated degradation of integral inner Nuclear Membrane protein emerin in fibroblasts lacking a type lamins
Biochemical and Biophysical Research Communications, 2006Co-Authors: Antoine Muchir, Catherine Massart, Baziel G M Van Engelen, Martin Lammens, Gisele Bonne, Howard J WormanAbstract:We previously identified and characterized a homozygous LMNA nonsense mutation leading to the absence of A-type lamins in a premature neonate who died at birth. We show here that the absence of A-type lamins is due to degradation of the aberrant mRNA transcript with a premature termination codon. In cultured fibroblasts from the subject with the homozygous LMNA nonsense mutation, there was a decreased steady-state expression of the integral inner Nuclear Membrane proteins emerin and nesprin-1alpha associated with their mislocalization to the bulk endoplasmic reticulum and a hyperphosphorylation of emerin. To determine if decreased emerin expression occurred post-translationally, we treated cells with a selective proteasome inhibitor and observed an increase in expression. Our results show that mislocalization of integral inner Nuclear Membrane proteins to the endoplasmic reticulum in human cells lacking A-type lamins leads to their degradation and provides the first evidence that their degradation is mediated by the proteasome.
-
dependence of diffusional mobility of integral inner Nuclear Membrane proteins on a type lamins
Biochemistry, 2006Co-Authors: Cecilia Ostlund, Colin L Stewart, Teresa Sullivan, Howard J WormanAbstract:Integral proteins of the Nuclear envelope inner Membrane have been proposed to reach their sites by diffusion after their co-translational insertion in the rough endoplasmic reticulum. They are then retained in the inner Nuclear Membrane by binding to Nuclear structures. One such structure is the Nuclear lamina, an intermediate filament meshwork composed of A-type and B-type lamin proteins. Emerin, MAN1, and LBR are three integral inner Nuclear Membrane proteins. We expressed these proteins fused to green fluorescent protein in embryonic fibroblasts from wild-type mice and Lmna −/− mice, which lack A-type lamins. We then studied the diffusional mobilities of emerin, MAN1, and LBR using fluorescence recovery after photobleaching. We show that emerin and MAN1, but not LBR, are more mobile in the inner Nuclear Membrane of cells from Lmna −/− mice than in cells from wild-type mice. In cells from Lmna −/− mice expressing exogenous lamin A, the protein mobilities were similar to those in cells from wild-type mi...
-
man1 an inner Nuclear Membrane protein that shares the lem domain with lamina associated polypeptide 2 and emerin
Journal of Biological Chemistry, 2000Co-Authors: Feng Lin, Deborah Lyn Blake, Isabelle Callebaut, Ilona S Skerjanc, Lars Holmer, Michael W Mcburney, Micheline Paulinlevasseur, Howard J WormanAbstract:Abstract The “MAN antigens” are polypeptides recognized by autoantibodies from a patient with a collagen vascular disease and localized to the Nuclear envelope. We now show that one of the human MAN antigens termed MAN1 is a 82.3-kDa protein with an amino-terminal domain followed by two hydrophobic segments and a carboxyl-terminal tail. The MAN1 gene contains seven protein-coding exons and is assigned to human chromosome 12q14. Its mRNA is approximately 5.5 kilobases and is detected in several different cell types that were examined. Cell extraction experiments show that MAN1 is an integral Membrane protein. When expressed in transfected cells, MAN1 is exclusively targeted to the Nuclear envelope, consistent with an inner Nuclear Membrane localization. Protein sequence analysis reveals that MAN1 shares a conserved globular domain of approximately 40 amino acids, which we term the LEM module, with inner Nuclear Membrane proteins lamina-associated polypeptide 2 and emerin. The LEM module is also present in two proteins ofCaenorhabditis elegans. These results show that MAN1 is an integral protein of the inner Nuclear Membrane that shares the LEM module with other proteins of this subcellular localization.
-
Nuclear Membrane dynamics and reassembly in living cells targeting of an inner Nuclear Membrane protein in interphase and mitosis
Journal of Cell Biology, 1997Co-Authors: Jan Ellenberg, Howard J Worman, Eric D Siggia, Jorge E Moreira, Carolyn L Smith, John F Presley, Jennifer LippincottschwartzAbstract:The mechanisms of localization and retention of Membrane proteins in the inner Nuclear Membrane and the fate of this Membrane system during mitosis were studied in living cells using the inner Nuclear Membrane protein, lamin B receptor, fused to green fluorescent protein (LBR–GFP). Photobleaching techniques revealed the majority of LBR–GFP to be completely immobilized in the Nuclear envelope (NE) of interphase cells, suggesting a tight binding to heterochromatin and/or lamins. A subpopulation of LBR–GFP within ER Membranes, by contrast, was entirely mobile and diffused rapidly and freely ( D = 0.41 ± 0.1 μm2/s). High resolution confocal time-lapse imaging in mitotic cells revealed LBR–GFP redistributing into the interconnected ER Membrane system in prometaphase, exhibiting the same high mobility and diffusion constant as observed in interphase ER Membranes. LBR–GFP rapidly diffused across the cell within the Membrane network defined by the ER, suggesting the integrity of the ER was maintained in mitosis, with little or no fragmentation and vesiculation. At the end of mitosis, Nuclear Membrane reformation coincided with immobilization of LBR–GFP in ER elements at contact sites with chromatin. LBR–GFP–containing ER Membranes then wrapped around chromatin over the course of 2–3 min, quickly and efficiently compartmentalizing Nuclear material. Expansion of the NE followed over the course of 30–80 min. Thus, selective changes in lateral mobility of LBR–GFP within the ER/NE Membrane system form the basis for its localization to the inner Nuclear Membrane during interphase. Such changes, rather than vesiculation mechanisms, also underlie the redistribution of this molecule during NE disassembly and reformation in mitosis.
-
signals and structural features involved in integral Membrane protein targeting to the inner Nuclear Membrane
Journal of Cell Biology, 1995Co-Authors: Bruno Soullam, Howard J WormanAbstract:We have examined transfected cells by immunofluorescence microscopy to determine the signals and structural features required for the targeting of integral Membrane proteins to the inner Nuclear Membrane. Lamin B receptor (LBR) is a resident protein of the Nuclear envelope inner Membrane that has a nucleoplasmic, amino-terminal domain and a carboxyl-terminal domain with eight putative transMembrane segments. The amino-terminal domain of LBR can target both a cytosolic protein to the nucleus and a type II integral protein to the inner Nuclear Membrane. Neither a Nuclear localization signal (NLS) of a soluble protein, nor full-length histone H1, can target an integral protein to the inner Nuclear Membrane although they can target cytosolic proteins to the nucleus. The addition of an NLS to a protein normally located in the inner Nuclear Membrane, however, does not inhibit its targeting. When the amino-terminal domain of LBR is increased in size from approximately 22.5 to approximately 70 kD, the chimeric protein cannot reach the inner Nuclear Membrane. The carboxyl-terminal domain of LBR, separated from the amino-terminal domain, also concentrates in the inner Nuclear Membrane, demonstrating two nonoverlapping targeting signals in this protein. Signals and structural features required for the inner Nuclear Membrane targeting of proteins are distinct from those involved in targeting soluble polypeptides to the nucleoplasm. The structure of the nucleocytoplasmic domain of an inner Nuclear Membrane protein also influences targeting, possibly because of size constraints dictated by the lateral channels of the Nuclear pore complexes.
K Arahata - One of the best experts on this subject based on the ideXlab platform.
-
distinct regions specify the Nuclear Membrane targeting of emerin the responsible protein for emery dreifuss muscular dystrophy
FEBS Journal, 2001Co-Authors: Y Tsuchiya, Hiroshi Yorifuji, M Ogawa, Asako Hase, K ArahataAbstract:Emery‐Dreifuss muscular dystrophy is a neuromuscular disorder that has three characteristics: (a) early contracture of the elbows, Achilles tendons and postcervical muscles; (b) slowly progressive wasting and weakness of skeletal muscle; and (c) cardiomyopathy with severe conduction block. The responsible gene for the X-linked recessive form of this disease encodes an inner Nuclear Membrane protein named emerin. Although emerin is absent in tissues from patients with this disorder, it remains obscure why the loss of this widely expressed protein affects selectively skeletal muscle, heart and joints. As the first step to address this question, we examined the molecular regions of emerin that are essential for Nuclear Membrane targeting and stability of the protein. We found that the C-terminal hydrophobic region was necessary, but not sufficient, for Nuclear Membrane anchoring and stability of the protein. In the absence of this transMembrane domain, the upstream nucleoplasmic domain showed no firm association with the Nuclear rim, but showed the tendency to accumulate at the nucleolus-like structures. Furthermore, proper targeting of emerin to the Nuclear Membrane required the latter half of the nucleoplasmic domain. These characteristics are distinct from those of lamina-associated polypeptide 2. Our findings indicate that emerin has distinct interactions with the inner Nuclear Membrane components that may be required for the stability and function of rigorously moving nuclei in tissues such as skeletal muscle, heart and joints.
-
emerin deficiency of which causes emery dreifuss muscular dystrophy is localized at the inner Nuclear Membrane
Neurogenetics, 1997Co-Authors: Hiroshi Yorifuji, Y Tadano, Y Tsuchiya, M Ogawa, K Goto, A Umetani, Y Asaka, K ArahataAbstract:X-linked recessive Emery-Dreifuss muscular dystrophy (EDMD) is an inherited muscle disorder characterized by the clinical triad of progressive wasting of humero-peroneal muscles, early contractures of the elbows, Achilles tendons and postcervical muscles, and cardiac conduction block with a high risk of sudden death. The gene for EDMD on Xq28 encodes a novel protein named emerin that localizes at the Nuclear Membrane of skeletal, cardiac and smooth muscles and some other non-muscle tissues. To investigate a possible physiological role for emerin, we examined the ultrastructural localization of the protein in human skeletal muscle and HeLa cells, using ultrathin cryosections. We found that the immune-labeled colloidal gold particles were localized on the nucleoplasmic surface of the inner Nuclear Membrane, but not on the Nuclear pore. Emerin stayed on the cytoplasmic surface of the Nuclear lamina, even after detergent treatment that solubilizes Membrane lipids and washes out Membrane proteins. These results suggest that emerin anchors at the inner Nuclear Membrane through the hydrophobic stretch, and protrudes from the hydrophilic region to the nucleoplasm where it interacts with the Nuclear lamina. We speculate that emerin contributes to maintain the Nuclear structure and stability, as well as Nuclear functions, particularly in muscle tissues that have severe stress with rigorous contraction-relaxation movements and calcium flux.
-
emerin deficiency at the Nuclear Membrane in patients with emery dreifuss muscular dystrophy
Nature Genetics, 1996Co-Authors: Atsushi Nagano, Yukiko K. Hayashi, M Ogawa, Ritsuko Koga, Yoshihiro Kurano, Junya Kawada, Ryozo Okada, Toshifumi Tsukahara, K ArahataAbstract:Emerin deficiency at the Nuclear Membrane in patients with Emery-Dreif uss muscular dystrophy
Kunxin Luo - One of the best experts on this subject based on the ideXlab platform.
-
the integral inner Nuclear Membrane protein man1 physically interacts with the r smad proteins to repress signaling by the transforming growth factor β superfamily of cytokines
Journal of Biological Chemistry, 2005Co-Authors: Deng Pan, Luis D Estevezsalmeron, Shannon L Stroschein, Xueliang Zhu, Sharleen Zhou, Kunxin LuoAbstract:Smad proteins are critical intracellular mediators of the transforming growth factor-beta, bone morphogenic proteins (BMPs), and activin signaling. Upon ligand binding, the receptor-associated R-Smads are phosphorylated by the active type I receptor serine/threonine kinases. The phosphorylated R-Smads then form heteromeric complexes with Smad4, translocate into the nucleus, and interact with various transcription factors to regulate the expression of downstream genes. Interaction of Smad proteins with cellular partners in the cytoplasm and nucleus is a critical mechanism by which the activities and expression of the Smad proteins are modulated. Here we report a novel step of regulation of the R-Smad function at the inner Nuclear Membrane through a physical interaction between the integral inner Nuclear Membrane protein MAN1 and R-Smads. MAN1, through the RNA recognition motif, associates with R-Smads but not Smad4 at the inner Nuclear Membrane in a ligand-independent manner. Overexpression of MAN1 results in inhibition of R-Smad phosphorylation, heterodimerization with Smad4 and Nuclear translocation, and repression of transcriptional activation of the TGFbeta, BMP2, and activin-responsive promoters. This repression of TGFbeta, BMP2, and activin signaling is dependent on the MAN1-Smad interaction because a point mutation that disrupts this interaction abolishes the transcriptional repression by MAN1. Thus, MAN1 represents a new class of R-Smad regulators and defines a previously unrecognized regulatory step at the Nuclear periphery.
-
the integral inner Nuclear Membrane protein man1 physically interacts with the r smad proteins to repress signaling by the transforming growth factor β superfamily of cytokines
Journal of Biological Chemistry, 2005Co-Authors: Deng Pan, Luis D Estevezsalmeron, Shannon L Stroschein, Xueliang Zhu, Sharleen Zhou, Kunxin LuoAbstract:Smad proteins are critical intracellular mediators of the transforming growth factor-β, bone morphogenic proteins (BMPs), and activin signaling. Upon ligand binding, the receptor-associated R-Smads are phosphorylated by the active type I receptor serine/threonine kinases. The phosphorylated R-Smads then form heteromeric complexes with Smad4, translocate into the nucleus, and interact with various transcription factors to regulate the expression of downstream genes. Interaction of Smad proteins with cellular partners in the cytoplasm and nucleus is a critical mechanism by which the activities and expression of the Smad proteins are modulated. Here we report a novel step of regulation of the R-Smad function at the inner Nuclear Membrane through a physical interaction between the integral inner Nuclear Membrane protein MAN1 and R-Smads. MAN1, through the RNA recognition motif, associates with R-Smads but not Smad4 at the inner Nuclear Membrane in a ligand-independent manner. Overexpression of MAN1 results in inhibition of R-Smad phosphorylation, heterodimerization with Smad4 and Nuclear translocation, and repression of transcriptional activation of the TGFβ, BMP2, and activin-responsive promoters. This repression of TGFβ, BMP2, and activin signaling is dependent on the MAN1-Smad interaction because a point mutation that disrupts this interaction abolishes the transcriptional repression by MAN1. Thus, MAN1 represents a new class of R-Smad regulators and defines a previously unrecognized regulatory step at the Nuclear periphery.
Gabriele A. Fontana - One of the best experts on this subject based on the ideXlab platform.
-
Rif1 S-acylation mediates DNA double-strand break repair at the inner Nuclear Membrane.
Nature Communications, 2019Co-Authors: Gabriele A. Fontana, Julia K. Reinert, Stefano Mattarocci, Benoît Falquet, Dominique Klein, Nicolas H. Thomä, David Shore, Daniel Heß, Ulrich RassAbstract:Rif1 is involved in telomere homeostasis, DNA replication timing, and DNA double-strand break (DSB) repair pathway choice from yeast to human. The molecular mechanisms that enable Rif1 to fulfill its diverse roles remain to be determined. Here, we demonstrate that Rif1 is S-acylated within its conserved N-terminal domain at cysteine residues C466 and C473 by the DHHC family palmitoyl acyltransferase Pfa4. Rif1 S-acylation facilitates the accumulation of Rif1 at DSBs, the attenuation of DNA end-resection, and DSB repair by non-homologous end-joining (NHEJ). These findings identify S-acylation as a posttranslational modification regulating DNA repair. S-acylated Rif1 mounts a localized DNA-damage response proximal to the inner Nuclear Membrane, revealing a mechanism of compartmentalized DSB repair pathway choice by sequestration of a fatty acylated repair factor at the inner Nuclear Membrane.
