Molecular consequences of deletion of the cytoplasmic domain of bullous pemphigoid 180 in a patient with predominant features of epidermolysis bullosa simplex.

Abstract	Bullous pemphigoid antigen 2 (BP180; COL17A1) collagen gene mutations typically result in nonlethal junctional epidermolysis bullosa. We have identified a patient, who had phenotypic features of mainly epidermolysis bullosa simplex and evidence for both intraepidermal and junctional blister formation. Mutation analysis disclosed compound heterozygous mutations in the COL17A1 gene, leading to deletion of Ile-18 to Asn-407 from the intracellular domain of BP180, BP180 Delta 18-407. To gain insight into the mechanisms underlying the phenotype, we have investigated the functional consequences of this truncation in BP180. The results demonstrate that: (1) in cultured keratinocytes of the patient, the assembly of hemidesmosomes, and their linkage with intermediate filaments are impaired; (2) BP180 Delta 18-407 is not capable of binding to the hemidesmosomal components BP230, plectin, and the beta 4 subunit of the alpha 6 beta 4 integrin in yeast two-hybrid assays; (3) BP180 Delta 18-407 is recruited into hemidesmosome-like structures in both normal and BP180-deficient transfected keratinocytes when ectopically expressed, suggesting that the extracellular domain of BP180 Delta 18-407 determines its topogenic fate; and, finally (4) the proteolytic shedding of the extracellular domain of BP180 Delta 18-407 is not impaired in transfected COS-7 cells. Collectively, the data demonstrate that the truncation of the intracellular domain of BP180 impairs the organization of hemidesmosomes, affecting both the mechanical stability of basal keratinocytes and dermoepidermal cohesion.
Authors	Lionel Fontao, Kaisa Tasanen, Marcel Huber, Daniel Hohl, Jan Koster, Leena Bruckner-Tuderman, Arnoud Sonnenberg, Luca Borradori
Journal	The Journal of investigative dermatology (J Invest Dermatol) Vol. 122 Issue 1 Pg. 65-72 (Jan 2004) ISSN: 0022-202X [Print] United States
PMID	14962091 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
Chemical References	Autoantigens Carrier Proteins Cytoskeletal Proteins DST protein, human Dystonin Integrin beta4 Nerve Tissue Proteins Non-Fibrillar Collagens
Topics	Animals Autoantigens (chemistry, genetics, metabolism) COS Cells Carrier Proteins Cytoplasm Cytoskeletal Proteins Dystonin Epidermolysis Bullosa Simplex (genetics, pathology) Gene Deletion Hemidesmosomes (pathology) Humans Integrin beta4 (metabolism) Keratinocytes (physiology, ultrastructure) Microscopy, Immunoelectron Nerve Tissue Proteins Non-Fibrillar Collagens Protein Binding Protein Processing, Post-Translational Protein Structure, Tertiary Transfection Collagen Type XVII

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