Search results for "Extracellular"
showing 10 items of 1220 documents
Hsp60 is actively secreted by human tumor cells
2010
Background Hsp60, a Group I mitochondrial chaperonin, is classically considered an intracellular chaperone with residence in the mitochondria; nonetheless, in the last few years it has been found extracellularly as well as in the cell membrane. Important questions remain pertaining to extracellular Hsp60 such as how generalized is its occurrence outside cells, what are its extracellular functions and the translocation mechanisms that transport the chaperone outside of the cell. These questions are particularly relevant for cancer biology since it is believed that extracellular chaperones, like Hsp70, may play an active role in tumor growth and dissemination. Methodology/Principal Findings S…
Neuronal cell cultures: A tool for investigations in developmental neurobiology
1992
The aim of this review is to describe environmental requirements for survival of neuronal cells in culture, and secondly to survey the complex interplay between hormones, neurotrophic factors, transport- and extracellular matrix- proteins, which characterize the developmental program of differentiating neurons. An overall reconsideration of the literature in this vast field is above the limits of the present paper; since progress and refinement in the techniques of neuronal cell cultures have paralleled the advancement in Developmental Neurobiology, we will run instead through the main steps which form the conceptual framework of neuronal cell cultures. © 1992 Plenum Publishing Corporation.
TIMP-3 facilitates binding of target metalloproteinases to the endocytic receptor LRP-1 and promotes scavenging of MMP-1.
2020
AbstractMatrix metalloproteinases (MMPs) and the related families of disintegrin metalloproteinases (ADAMs) and ADAMs with thrombospondin repeats (ADAMTSs) play a crucial role in extracellular matrix (ECM) turnover and shedding of cell-surface molecules. The proteolytic activity of metalloproteinases is post-translationally regulated by their endogenous inhibitors, known as tissue inhibitors of metalloproteinases (TIMPs). Several MMPs, ADAMTSs and TIMPs have been reported to be endocytosed by the low-density lipoprotein receptor-related protein-1 (LRP-1). Different binding affinities of these proteins for the endocytic receptor correlate with different turnover rates which, together with di…
Shed membrane vesicles and clustering of membrane-bound proteolytic enzymes
2003
Publisher Summary Eukaryotic cells appear to release into the extracellular medium several populations of exovesicles, which are suggested to have different origins and functions and are identified by different names. This chapter deals with vesicles believed to originate from the cell membrane and named membrane vesicles. These are structures in which membrane-bound proteolytic enzymes are clustered and they play important roles in matrix remodeling. Relatively large membrane vesicles (diameters ranging from 100 nm to 1 μm) are shed from plasma membranes through unidentified budding mechanisms. These membrane structures are enriched in selected plasma-membrane components including integrin…
Characterization of the Receptor Protein-Tyrosine Kinase Gene from the Marine Sponge Geodia cydonium
1996
Cells are provided with well-defined receptor structures (signal receivers) which interact with their corresponding ligands (signal molecules) and initiate a signal transduction pathway resulting in a change of cellular behavior or metabolism (Stoddard et al. 1992). It is well established that cells from both eukaryotic protists (single-cell organisms) and from Metazoa (multicellular organisms) respond to signals emanating from the extracellular environment. The extracellular signals to which protists respond are mainly nutrients which diffuse to their surfaces, and in most cases cross the cell membrane. In addition, they are able to bind peptide hormones, e.g., insulin or adrenocorticotrop…
Concentration-dependent T cell activation by different types of proteins
2009
We investigated the concentration-dependent stimulation of T cells by different human proteins. Quantitative changes in the extent of activation, as well as qualitative changes within the type of activation, were measured. At low, physiological concentrations of extracellular human proteins (0.2 µg/ml), CD4 and CD8 T lymphocytes were suppressed. In contrast, at high protein concentrations (2 mg/ml), CD4 T cells were suppressed, but we also observed a concurrent increase in the level of CD8 T cell activation. Our results are consistent with the phenomenon of cross-presentation, whereby the addition of intracellular proteins leads to the activation of both CD4 and CD8 T cells. Further additio…
Human Hsp10 and Early Pregnancy Factor (EPF) and their relationship and involvement in cancer and immunity: current knowledge and perspectives.
2009
This article is about Hsp10 and its intracellular and extracellular forms focusing on the relationship of the latter with Early Pregnancy Factor and on their roles in cancer and immunity. Cellular physiology and survival are finely regulated and depend on the correct functioning of the entire set of proteins. Misfolded or unfolded proteins can cause deleterious effects and even cell death. The chaperonins Hsp10 and Hsp60 act together inside the mitochondria to assist protein folding. Recent studies demonstrated that these proteins have other roles inside and outside the cell, either together or independently of each other. For example, Hsp10 was found increased in the cytosol of different t…
An unconventional role for miRNA: let-7 activates Toll-like receptor 7 and causes neurodegeneration
2011
Activation of innate immune receptors by host-derived factors exacerbates CNS damage, but the identity of these factors remains elusive. We uncovered an unconventional role for the microRNA let-7, a highly abundant regulator of gene expression in the CNS, in which extracellular let-7 activates the RNA-sensing Toll-like receptor (TLR) 7 and induces neurodegeneration through neuronal TLR7. Cerebrospinal fluid (CSF) from individuals with Alzheimer’s disease contains increased amounts of let-7b, and extracellular introduction of let-7b into the CSF of wild-type mice by intrathecal injection resulted in neurodegeneration. Mice lacking TLR7 were resistant to this neurodegenerative effect, but thi…
Oxidative Stress, Induced by Sub-Lethal Doses of BDE 209, Promotes Energy Management and Cell Cycle Modulation in the Marine Fish Cell Line SAF-1
2019
The effects of sub-lethal doses of polybrominated diphenyl ether (PBDE)-209 in terms of toxicity, oxidative stress, and biomarkers were evaluated in the Sparus aurata fibroblast cell line (SAF-1). Vitality and oxidative stress status were studied after incubation with PBDE for 72 h. Concomitantly, the quantification of proteins related to cell cycle and DNA repair (p53), cell proliferation (extracellular signal&ndash
Exosomal Heat Shock Proteins as New Players in Tumour Cell-to-cell Communication
2014
Exosomes have recently been proposed as novel elements in the study of intercellular communication in normal and pathological conditions. The biomolecular composition of exosomes reflects the specialized functions of the original cells. Heat shock proteins (Hsps) are a group of chaperone proteins with diverse biological roles. In recent years, many studies have focused on the extracellular roles played by Hsps that appear to be involved in cancer development and immune system stimulation. Hsps localized on the surface of exosomes, secreted by normal and tumour cells, could be key players in intercellular cross-talk, particularly during the course of different diseases, such as cancer. Exoso…