0000000000020107
AUTHOR
Claudia Koch-brandt
showing 16 related works from this author
Denaturation via Surfactants Changes Composition of Protein Corona
2018
The use of nanocarriers as drug delivery vehicles brings them into contact with blood plasma proteins. Polymeric nanocarriers require some sort of surfactant to ensure colloidal stability. Formation of the protein corona is therefore determined not only by the intrinsic properties of the nanocarrier itself but also by the accompanying surfactant. Although it is well-known that surfactants have an impact on protein structure, only few studies were conducted on the specific effect of surfactants on the composition of protein corona of nanocarriers. Therefore, we analyzed the composition of the protein corona on "stealth" nanoparticles with additional surfactant (cetyltrimethylammonium chlorid…
Clusterin gene expression in apoptotic MDCK cells is dependent on the apoptosis-inducing stimulus
1995
Abstract Clusterin (Apolipoprotein J, complement lysis inhibitor) is a widely expressed multifunctional glycoprotein. The expression of clusterin mRNA has been reported to be elevated in a broad spectrum of apoptotic or degenerative tissues. More recently, it was shown that within these tissues clusterin is expressed in the surviving rather than in the dying cells, and that clusterin gene expression is actually down-regulated in the apoptotic cells. We have studied the expression of the clusterin gene in apoptotic MDCK cells. Cell death was initiated by three different stimuli: application of the steroid hormone antagonist RU 486, activation of protein kinase C by the application of the pho…
Gp80 (clusterin; TRPM-2) mRNA level is enhanced in human renal clear cell carcinomas
1994
The gp80 glycoprotein complex (clusterin, apolipoprotein J, TRPM-2) is a widely expressed protein that has been attributed functions in tissue remodelling, immune defense and transport of lipids and biologically active peptides. The expression of the protein appears to be elevated in several neurodegenerative, apoptotic and malignant processes. We show here that in patients with renal clear cell carcinoma gp80 mRNA is 3-fold overexpressed in tissue of the tumors compared with adjacent non-tumor tissue.
Nerve growth factor and epidermal growth factor stimulate clusterin gene expression in PC12 cells
1999
Clusterin (apolipoprotein J) is an extracellular glycoprotein that might exert functions in development, cell death and lipid transport. Clusterin gene expression is elevated at sites of tissue remodelling, such as differentiation and apoptosis; however, the signals responsible for this regulation have not been identified. We use here the clusterin gene as a model system to examine expression in PC12 cells under the control of differentiation and proliferation signals produced by nerve growth factor (NGF) and by epidermal growth factor (EGF) respectively. NGF induced clusterin mRNA, which preceded neurite outgrowth typical of neuronal differentiation. EGF also activated the clusterin mRNA, …
Apolipoprotein-mediated transport of nanoparticle-bound drugs across the blood-brain barrier.
2002
Recent studies have shown that drugs that are normally unable to cross the blood-brain barrier (BBB) following intravenous injection can be transported across this barrier by binding to poly(butyl cyanoacrylate) nanoparticles and coating with polysorbate 80. However, the mechanism of this transport so far was not known. In the present paper, the possible involvement of apolipoproteins in the transport of nanoparticle-bound drugs into the brain is investigated. Poly(butyl cyanoacrylate) nanoparticles loaded with the hexapeptide dalargin were coated with the apolipoproteins AII, B, CII, E, or J without or after precoating with polysorbate 80. In addition, loperamide-loaded nanoparticles were …
Overexpression of apolipoprotein J in human fibroblasts protects against cytotoxicity and premature senescence induced by ethanol and tert-butylhydro…
2008
Human diploid fibroblasts (HDFs) exposed to subcytotoxic stresses under H2O2, tert-butylhydroperoxide (t-BHP), and ethanol (EtOH) undergo stress-induced premature senescence (SIPS) characterized by many biomarkers of HDFs replicative senescence. Among these biomarkers are a growth arrest, an increase in the senescence-associated β-galactosidase activity, a senescent morphology, an overexpression of p21waf-1 and the subsequent inability to phosphorylate pRb, the presence of the common 4977-bp mitochondrial deletion, and an increase in the steady-state level of several senescence-associated genes such as apolipoprotein J (apo J). Apo J has been described as a survival gene against cytotoxic s…
Purification and Characterization of <I>Bacillus cereus</I> Protease Suitable for Detergent Industry
2005
An extracellular alkaline protease from an alkalophilic bacterium, Bacillus cereus, was produced in a large amount by the method of extractive fermentation. The protease is thermostable, pH tolerant, and compatible with commercial laundry detergents. The protease purified and characterized in this study was found to be superior to endogenous protease already present in commercial laundry detergents. The enzyme was purified to homogeneity by ammonium sulfate precipitation, concentration by ultrafiltration, anion-exchange chromatography, and gel filtration. The purified enzyme had a specific activity of 3256.05 U/mg and was found to be a monomeric protein with a molecular mass of 28 and 31 kD…
Dithiothreitol Treatment of Madin-Darby Canine Kidney Cells Reversibly Blocks Export from the Endoplasmic Reticulum but Does Not Affect Vectorial Tar…
1995
Addition of dithiothreitol (DTT) to the culture medium of Madin-Darby canine kidney (MDCK) cells blocks transport of newly synthesized gp80 (clusterin, apolipoprotein J), a soluble marker protein for apical exocytosis in this epithelial cell line. In cells treated with DTT during pulse labeling, gp80 is retained in the endoplasmic reticulum. After removal of the reducing agent, gp80 is posttranslationally oxidized and secreted at the apical surface of MDCK cell monolayers. This demonstrates that when folded and oxidized posttranslationally, gp80 can acquire a conformation that exhibits sorting signals for vectorial targeting. In the continuous presence of DTT, the transepithelial electrical…
Sorting of a secretory protein (gp80) to the apical surface of Caco-2 cells
1994
We have investigated the synthesis and polarized secretion of the exogenous gp80 glycoprotein complex in the human epithelial adenocarcinoma cell line, Caco-2. gp80 is secreted at the apical surface of Madin-Darby canine kidney (MDCK) cells and should, therefore, display the signal(s) required for sorting into the apical exocytic pathway. In Caco-2 cells, no bona fide secretory protein released preferentially at the apical surface has been described so far. To address the question of whether Caco-2 cells possess a machinery capable of delivery of secretory proteins at the apical surface, we stably transfected the cells with a recombinant gene coding for the gp80 glycoprotein complex. Pulse-…
Multiple Receptors Mediate apoJ-Dependent Clearance of Cellular Debris into Nonprofessional Phagocytes
2001
Phagocytosis of apoptotic, senescent, and dying cells by macrophages is a well characterized process. More recently it has been shown that in addition to macrophages vital neighboring cells in the affected tissue participate in the cellular clearance. While scavenger receptors have been shown to mediate uptake into macrophages, it is poorly understood how cellular debris is internalized by nonprofessional phagocytes. We here analyze the endocytic activity of vital fibroblasts and epithelial cells exposed to cellular debris and membrane remnants. We show a mutual stimulation in the endocytosis of debris and apolipoproteinJ (clusterin) in these cells. Experiments using RAP (receptor-associate…
Apical transport of osteopontin is independent of N-glycosylation and sialylation.
2002
Studies of how epithelial surface polarity into apical and basolateral domains is generated and maintained have proposed that carbohydrate modifications serve as apical targeting signals for proteins by interacting with lectin sorters. However, the experimental evidence in support of N-glycans, O-glycans and sialic acids mediating apical transport is still very controversial. This could be partly due to the fact that in most studies exogenously expressed proteins were analysed. One has, therefore, examined the role of carbohydrate moieties in apical targeting of the endogenous secretory protein osteopontin in MDCK cells. It was found, however, that sorting of osteopontin does not require N-…
Chapter 7 Cell Protective Functions of Secretory Clusterin (sCLU)
2009
Secretory clusterin (sCLU) is found as an 80-kDa glycoprotein in virtually all body fluids, in serum it is associated with high-density lipoprotein (HDL). Here, we discuss demonstrated and proposed mechanisms of the cytoprotective functions of sCLU in instances of apoptosis, necrosis, and disease. These include prevention from cell damage by lipid oxidation in blood vessels, removal of dead cell remnants in tissues undergoing various forms of cell death, and clearance of harmful extracellular molecules such as amyloid beta (Aβ) by endocytosis or transcytosis. All these functions may reflect the propensity of sCLU to bind to a wide spectrum of hydrophobic molecules on one hand and to specifi…
Apoptotic Cell Debris and Phosphatidylserine-Containing Lipid Vesicles Induce Apolipoprotein J (Clusterin) Gene Expression in Vital Fibroblasts
2001
The molecular events in cells undergoing programmed cell death (apoptosis) are well studied; however, the response of the surviving neighbor cells to local cell death is largely uncharacterized. Apolipoprotein J (clusterin) is an 80-kDa glycoprotein that has been implied in cytoprotection of the vital cells, presumably by assisting in the clearance of apoptotic vesicles and membrane remnants. Its mRNA is specifically up-regulated in the vital cells of apoptotic tissues. The molecular mechanisms, however, leading to this response are not known. We here show that exposure of vital fibroblasts to apoptotic vesicles, disrupted vital cells, and trypsin-treated membrane remnants induces apoJ mRNA…
Toll-like receptor 3 mediates expression of clusterin/apolipoprotein J in vascular smooth muscle cells stimulated with RNA released from necrotic cel…
2010
Clusterin/Apolipoprotein J is a protein that is upregulated in a broad spectrum of diverse pathological processes. The predominant form is a secreted glycoprotein (sCLU) with cytoprotective and anti-inflammatory properties which shows enhanced expression in vascular smooth muscle cells (VSMC) following aortic injury and in atherosclerotic disease. Recent evidence indicates that during atherosclerosis, Toll-like receptors (TLRs) are activated in vascular cells by endogenous ligands. Here, we analyzed whether CLU expression in VSMC is controlled by TLRs, and stimulated by factors associated with or released by necrotic cells. Activation of TLR3 by the synthetic RNA analogue polyinosinic-polyc…
Differential regulation of the clusterin gene by Ha-ras and c-myc oncogenes and during apoptosis
1998
Clusterin (ApoJ) is an extracellular glycoprotein expressed during processes of tissue differentiation and regression that involve programmed cell death (apoptosis). Increased clusterin expression has also been found in tumors, however, the mechanism underlying this induction is not known. Apoptotic processes in tumors could be responsible for clusterin gene activation. Alternatively, oncogenic mutations could modulate signal transduction, thereby inducing the gene. We examined the response of the rat clusterin gene to two oncogenes, Ha-ras and c-myc, in transfected Rat1 fibroblasts. While c-myc overexpression did not modify clusterin gene activity, the Ha-ras oncogene produced a seven to t…
The Chaperone Activity of Clusterin is Dependent on Glycosylation and Redox Environment
2014
Background/Aims: Clusterin (CLU), also known as Apolipoprotein J (ApoJ) is a highly glycosylated extracellular chaperone. In humans it is expressed from a broad spectrum of tissues and related to a plethora of physiological and pathophysiological processes, such as Alzheimer's disease, atherosclerosis and cancer. In its dominant form it is expressed as a secretory protein (secreted CLU, sCLU). During its maturation, the sCLU-precursor is N-glycosylated and cleaved into an α- and a β-chain, which are connected by five symmetrical disulfide bonds. Recently, it has been demonstrated that besides the predominant sCLU, rare intracellular CLU forms are expressed in stressed cells. Since these for…