Hemidesmosomes filaments

Intermediate filament associated proteins (IFAPs) coordinate interactions between intermediate filaments (IFs) and other cytoskeletal elements and organelles, including membrane-associated junctions such as desmosomes and hemidesmosomes in epithelial cells, costameres in striated muscle, and intercalated discs in cardiac muscle. IFAPs thus serve as critical connecting links in the IF scaffolding that organizes the cytoplasm and confers mechanical stability to cells and tissues. However, in recent years it has become apparent that IFAPs are not limited to structural... 

Skalli, O., Jones,J. C. R., Gagescu, R., and Goldman, R. D. (1994). IFAP 300 is common to desmosomes and hemidesmosomes and is a possible linker of intermediate filaments to these junctions. /. Biol. Chem. 125, 159-170. 

Gerecke, D., Gordon, M., Wagman, L., Champliaud, M., Burgeson, R. (1994). Hemidesmosomes, anchoring filaments, and anchoring fibrils components of a unique attachment complex. In Biology of Extracellular Matrix (P.D. Yurchenco, D.E. Birk, R.E. Mecham, eds), pp. 417-39. Academic Press, Orlando, FL. 

Hemidesmosomes (HDs) are membrane-associated adhesive junctions linked to the filamentous networks of the epithelial cell cytoskeleton and the lamina lucida ( light green/ dark blue region in Fig. 5.1). The cytoskeleton of all mammalian cells is composed of three kinds of filaments microfilaments, intermediate filaments and microtubules. Microfilaments... 

Plakin proteins link intracellular keratin intermediate filaments to hemidesmosomes of basal epidermal cells, or to desmosomes on suprabasal epidermal cells (Sect. 5.2.1), whereas type XVII collagen (the only collagen secreted by epithelial cells ) and integrins attach hemidesmosomes to a basal lamina. Three p 1 integrins (with al, a3 or a5 partners)... 

The keratin family of proteins comprises two of the six classes of intermediate filament proteins found in the cytosol of eukaryotic cells. They provide the intracellular structural stability that complements the intercellular mechanical cohesion provided by desmosomes. Keratin filaments cross the entire cytosol of keratinocytes and their ends are tightly attached to desmosomes by desmoplakin (Fig. 5.9) or, in basal cells, to the related plakin (BP230) and plectin proteins in hemidesmosomes. 

A FIGURE 5-32 Fluorescence micrograph of a PtK2 fibroblast cell stained to reveal keratin intermediate filaments. A network of filaments crisscrosses the cell from the nucleus to the plasma membrane. At the plasma membrane, the filaments are linked by adapter proteins to two types of anchoring junctions desmosomes between adjacent cells and hemidesmosomes between the cell and the matrix. [Courtesy of R. D. Goldman.]... 

The basement membrane zone or epidermal-dermal junction is a thin extracellular matrix that separates the epidermis from the dermis. It is a highly specialized structure recognized with the light microscope as a thin, homogeneous band. Ultra-structurally, it can be divided into four component layers (1) the cell membrane of the basal epithelial cell, which includes the hemidesmosomes (2) the lamina ludda (lamina rara) (3) the lamina densa (basal lamina) and (4) the subbasal lamina (sublamina densa or reticular lamina), with a variety of fibrous structures (anchoring fibrils, dermal microfibril bundles, microthreadlike filaments) (Briggaman and Wheeler, 1975). The basement membrane has a complex molecular architecture with numerous components that play a key role in adhesion of the epidermis to the dermis. The macromolecules that are ubiquitous components of all basement membranes... 

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