Identification of a new hemidesmosomal protein, HD1: a major, high molecular mass component of isolated hemidesmosomes.

Abstract

Abstract. Hemidesmosomes (HDs) mediate cell adhesion to the extracellular matrix and have morphological association with intermediate-sized filaments (IFs) through cytoplasmic plaques . Though several proteins have been located in HDs, most of them have not been well characterized, with the exception of the 230-kD antigen of bullous pemphigoid (BP), an autoimmune skin blistering disease. Only recently we have succeeded in isolating HDs from bovine corneal epithelial cells and in identifying five major components on SDS-PAGE (Owaribe K., Y. Nishizawa, and W. W. Franke . 1991 . Exp. Cell Res . 192 :622-630) . In this study we report on immunological characterization of one of the major components, termed HDl, with an H EMIDESMOSOMES (HDs)' and focal adhesions are cell junctions that mediate adhesion to the extracellular matrix (ECM) . These two plasma membrane junction types have common ultrastructural features ; e.g., both are associated with cytoskeeeool elements through electron-dense cytoplasmic plaques. They thus provide us with models to explore the mechanisms of transmembrane connection between the ECM and the cytoskeleton. In focal adhesions associated with actin-containing microfilaments (for reviews see references 2 and 50), a number ofproteins are known to be involved, including ECM receptors of the integrin family (5,12,17,33) and plaque components such as talin (1) and vinculin (29) . Yet our knowledge about the molecular architecture of the ECM-to-microfilaments junctions is still incomplete.The HD, primarily found in the basement membrane zone (BMZ) of stratified and complex epithelia, has a complex structure: a cytoplasmic plaque associated with intermediate filaments (IFs), a subbasal dense plate with anchoring filaments in the basal lamina, and anchoring fibrils in collagenous connective tissues (6,16,39). The morphological appearance is essentially that of half of the desmosome of intercellular junctions. However, although several des- apparent molecular mass of 500 kD. Immunofluorescence microscopy showed colocalization of HDl with BP antigen at the basement membrane zone of those tissues that have typical HDs, including skin epidermis, corneal and tracheal epithelia, and myoepithelium . In cultured keratinocytes, HDl demonstrated colocalization with BP antigen in the precise way, while being absent from focal adhesions . Immunoelectron microscopy revealed that an epitope of HDl was located on the cytoplasmic side of HDs . Taking all these results together, we conclude that HDl is a new hemidesmosomal component . Interestingly, HDl also exists in endothelial and glial cells, which lack typical HDs . mosomal proteins have been identified (e.g., references 4, 26; for review see reference 35) since the establishment of appropriate isolation procedures (e.g., reference 36), none of them have been found in HDs (13, 35) . Thus, in marked contrast to other celljunctions, little information is available about the molecular components of HDs, with the exception ofthe well-characterized 230-kD antigen r...

Genetic ablation of the alpha 6‐integrin subunit in Tie1Cre mice enhances tumour angiogenesis

“…Interestingly, β4-integrin subunit levels are undetectable on these endothelial cells. This finding corroborates results from Heida et al, where they also observed that cultured endothelial cells lose β4-integrin expression [38].…”

Integrin alpha 6 beta 4 forms a complex with the cytoskeletal protein HD1 and induces its redistribution in transfected COS-7 cells.

“…As shown in Figure 2, a high molecular mass protein of 500-kDa was bound to GST-cytof34A but not to GST alone or GST-cytoa6A. (Hieda et al, 1992), we compared the mobilities of these proteins in SDS-polyacrylamide gels. As shown in Figure 4A, tein is weaker than that of {34A.…”

“…Proteins that might be involved in this linkage are BP230 (Stanley et al, 1981), plectin (Wiche et al, 1984), (Skalli et al, 1994), HD1 (Hieda et al, 1992), and the 200-kDa 6A5 antigen . Plectin and IFAP-300 bind IF in vitro (Foisner et al, 1988;Skalli et al, 1994).…”

Targeted inactivation of plectin reveals essential function in maintaining the integrity of skin, muscle, and heart cytoarchitecture

“…Plectin or its putative isoform HD1 (Hieda et al 1992) have been shown to colocalize with IF-associated as well as actin-based cell junctional complexes, including hemidesmosomes, desmosomes, focal contacts of cells in culture, dense plaques of smooth muscle, and other junctional adhesive complexes (Wiche et al 1983(Wiche et al , 1984Seifert et al 1992;Eger et al 1997;Sanchez-Aparicio et al 1997). This raises the question of whether the formation and/or functional integrity of such junctions were affected by plectin deficiency.…”