Structure and Function of Cartilage
Kyriacos A. Athanasiou, Eric M. Darling, Grayson D. DuRaine, Jerry C. Hu, A. Hari Reddi in Articular Cartilage, 2017
Structurally, intermediate filaments are 10 nm in diameter and “intermediate” in size, being smaller than microtubules but wider than actin microfilaments. Like actin, they play a similar role in resisting tensile forces and have also been indicated to play roles in cell-cell interactions, cell-matrix junctions, and mechanotransduction (Lazarides 1980; Wang et al. 1993). Unlike actin, the three-dimensional network of intermediate filaments helps to organize the internal arrangement of the organelles. Several different proteins make up the intermediate filaments based on cell type. In skin, the intermediate filament is keratin, whereas in neural cells it is lamin, although lamin is also a major component of the nuclear membrane in all cells. In contrast, in chondrocytes and most other cells, vimentin is the most common intermediate filament. The vimentin cytoskeleton has been implicated to play a role in chondrocyte homeostasis (Blain et al. 2006; Haudenschild et al. 2011).
From cells to systems
Nick Draper, Helen Marshall in Exercise Physiology, 2014
The cytoplasm, meaning cell-forming matter, comprises cytosol, a cytoskeleton and organelles which carry out a wide range of functions within the cell. Cytosol or intracellular fluid is a gel-like substance, largely composed of water that contains suspended and dissolved particles such as ATP, glucose, lipids, amino acids and a variety of different ions. Many metabolic reactions take place within the cytosol including glycolysis, one of the major pathways for synthesising ATP. The cytoskeleton is literally that, a cellular ‘skeleton’ within the cytoplasm which is made out of protein (see Figure 3.2). It includes three main types of protein filament that, among other roles, maintain cell structure and hold in place many of the cell’s organelles. The microtubules are responsible for support and structure within the cell giving the cytoskeleton strength and rigidity. The intermediate filaments give the cell strength, help to maintain the structure and stabilise the position of the cells organelles, while microfilaments (which are illustrated in Figure 3.5) help to give the cell shape by anchoring the cytoskeleton to the plasma membrane. The microfilaments (which are comprised of the protein actin) are also one of the filaments responsible for muscular contraction (see Chapter 5).
Cell Structure and Functions
Malgorzata Lekka in Cellular Analysis by Atomic Force Microscopy, 2017
Intermediate filaments (IFs) [1] are the third type of fibrous cytoskeletal components. Their diameter is about 10 nm so they are typically intermediate in size between microfilaments and microtubules. Unlike the microfilaments and microtubules, the intermediate filaments are made of several different proteins. Therefore, the intermediate filaments can be divided into five major types. Type I and II are composed of acidic and basic keratin, respectively. They are produced by different types of epithelial cells (i.e., bladder, skin). Type III encompasses intermediate filaments distributed in a number of cell types, including vimentin in fibroblasts, endothelial cells and leukocytes; desmin in muscle; glial fibrillary acidic factor in astrocytes and other types of glia; and peripherin in peripheral nerve fibers. Type IV are neurofilaments and type V are made of laminin (Fig. 2.18).
Alexander’s disease and the story of Louise*
Published in Neuropsychological Rehabilitation, 2018
Barbara A. Wilson, Faraneh Vargha-Khadem, Gerhard Florschutz
The disease is inherited in an autosomal dominant pattern. The affected gene is the glial fibrillary acidic protein or GFAP gene (Genetic Home Reference, 2015). The following quotation is from the same source. Mutations in the GFAP gene cause Alexander disease. The GFAP gene provides instructions for making a protein called glial fibrillary acidic protein. Several molecules of this protein bind together to form intermediate filaments, which provide support and strength to cells. Mutations in the GFAP gene lead to the production of a structurally altered glial fibrillary acidic protein. The altered protein is thought to impair the formation of normal intermediate filaments. As a result, the abnormal glial fibrillary acidic protein likely accumulates in astroglial cells, leading to the formation of Rosenthal fibres, which impair cell function. It is not well understood how impaired astroglial cells contribute to the abnormal formation or maintenance of myelin, leading to the signs and symptoms of Alexander disease.
Data-independent acquisition mass spectrometry reveals comprehensive plasma protein profiles in the natural history of patients with hereditary transthyretin amyloidosis (ATTRv)
Published in Expert Review of Proteomics, 2023
Shan He, XinYue He, RuoKai Pan, LuRong Pan, Xiaoying Lv, YuTong Jin, Yue Fan, YuTong Wang, Zhuang Tian, ShuYang Zhang
GO enrichment analysis is shown in Figure 2, and the top 10 GO function entries were identified based on their significance represented by –log10 p values in the three GO types. Figure 2a shows 30 DEPs between the ATTRv-PN and control groups. GO enrichment analysis showed that cornification, keratinization, phagocytosis, and programmed cell death were the most significant biological processes. Intermediate filaments, intermediate filament cytoskeletons, keratin filaments, and polymeric cytoskeletal fibers were the most significant cellular components. The structural constituents of the skin epidermis, hormone activity, and receptor regulator activity were the most significant molecular functions. KEGG pathway enrichment analysis (Figure 2b) showed the estrogen signaling pathway and cell adhesion molecule (CAM) pathway as the two pathways with a higher number of differentially expressed proteins and more reliable enrichment significance in ATTRv-PN.
Nestin and CD34 expression in colorectal cancer predicts improved overall survival
Published in Acta Oncologica, 2021
Athanasios Tampakis, Benjamin Weixler, Silvan Rast, Ekaterini-Christina Tampaki, Eleonora Cremonesi, Venkatesh Kancherla, Nadia Tosti, Christoph Kettelhack, Charlotte K. Y. Ng, Tarik Delko, Savas D. Soysal, Urs von Holzen, Evangelos Felekouras, Nikolaos Nikiteas, Martin Bolli, Luigi Tornillo, Luigi Terracciano, Serenella Eppenberger-Castori, Giulio C. Spagnoli, Salvatore Piscuoglio, Markus von Flüe, Silvio Däster, Raoul A. Droeser
The cytoskeleton of eukaryotic cells consist of three major filamentous components: actin, microtubules, and intermediate filament proteins [8]. Nestin belongs to class VI of intermediate filament proteins identified initially in neuroepithelial stem cells [9]. Substantial in vitro and in vivo information suggests the presence of nestin in cells with stem cell properties [8]. More specifically, tumor cells expressing nestin harbor aggressive clinical features as demonstrated in a variety of malignant tumors of diverse histological origin, including brain (gliomas) [10], breast [11] (triple-negative cancers – regulator of Wnt/β catenin pathway), liver (hepatocellular carcinoma) [12], kidney [13] (cancer stem cell subpopulation in renal cell carcinoma), and prostate [14] (carcinoma initiating stem cells). In some of these tumors, nestin expression correlates with resistance to conventional therapy [8]. Moreover, a possible positive feedback mechanism for tumor neovascularization between nestin-positive cancer cells and endothelial cells of tumor blood vessels has been suggested [8]. Besides, nestin-positive cells in healthy tissues might act as reserve participating in tissue repair processes such as those taking place after focal cerebral ischemia and unilateral ureteral obstruction [8].
Related Knowledge Centers
- Actin
- Cytoplasm
- Cytoskeleton
- Lamin
- Microfilament
- Microtubule
- Myosin
- Protein
- Mitochondrion
- Endoplasmic Reticulum