Molecular Biology of the 230-kD Bullous Pemphigoid Antigen

Abstract

The 230-kD bullous pemphigoid antigen is a hemidesmosomal protein of the cutaneous basement membrane zone. We have previously cloned overlapping cDNAs corresponding to the human 230-kD bullous pemphigoid antigen gene (BPAG1), located at the human chromosomal locus 6p11–12. Utilizing the cDNA clones, a genomic DNA λFIX II phage library was screened. Seven overlapping genomic clones, spanning ∼20 kb, were isolated. These clones were shown to contain the entire ∼ 9-kb coding sequence of BPAG1 and it consisted of 22 separate exons which varied from 78 to 2,810 bp in size. Elucidation of 2.6 kb of 5′-flanking DNA was found to contain several putative transcriptional response elements, and development of promoter chloramphenicol acetyltransferase (CAT) reporter gene constructs allowed identification of putative cis-elements which confer keratinocyte-specific expression to the gene. In particular, a putative AP2-binding sequence (KRE2) in the position ––(1,786––1,778) was shown to be responsible for marked enhancement of the endogenous promoter, as well as of a heterologous thymidine kinase/CAT construct, activity in normal human keratinocytes. Normal human keratinocyte nuclear extracts contained a protein, designated as KTP1, which complexed with the KRE2 oligomer by gel mobility shift assays. UV cross-linking and Southwestern analysis suggested that KTP1 is a DNA-binding protein clearly distinct from AP2, and this protein may be responsible for the basal keratinocyte-specific expression of the BPAG1 gene.

The Spectraplakin Short Stop Is an Actin–Microtubule Cross-Linker That Contributes to Organization of the Microtubule Network

“…Although spectraplakins have been evolutionarily conserved across animal genomes, they have been studied in greatest detail in Drosophila , in which the sole homologue is named Short stop (Shot), and mouse, which has two paralogues (dystonin/BPAG1 and ACF7/MACF2) (Tamai et al , 1994; Bernier et al , 1996; Gregory and Brown, 1998; Leung et al , 1999). Loss-of-function studies of spectraplakins have revealed several important functions for these proteins.…”

Unique role for the periplakin tail in intermediate filament association: specific binding to keratin 8 and vimentin

“…For example, plectin has been detected in perinuclear, hemidesmosomal and desmosomal locations, as well as in association with intermediate filaments (4–6). While desmoplakin connects the intermediate filaments to desmosomes (7, 8), BPAG1 makes the connection between the intermediate filaments and hemidesmosomes in epidermal basal cells (9). The neuronal isoform of BPAG1, known as dystonin, has been characterized as a linker between actin and intermediate filament cytoskeletons (10, 11).…”

Molecular Biological Aspects of Acquired Bullous Diseases

“…The entire full-length human antigen cDNA and the regulatory elements responsible for tissue expression of the gene were later isolated (Tamai et al, 1994). There is some homology between cDNA from the BP-230 which has an intracellular localization and the desmosomal plaque protein (Tanaka et al, 1991;Tang et al, 1996).…”