Loss of plectin causes epidermolysis bullosa with muscular dystrophy: cDNA cloning and genomic organization.
Plectin is a widely expressed high molecular weight protein that is involved in cytoskeleton-membrane attachment in epithelial cells, muscle, and other tissues. The human autosomal recessive disorder epidermolysis bullosa with muscular dystrophy (MD-EBS) shows epidermal blister formation at the level of the hemidesmosome and is associated with a myopathy of unknown etiology. Here, plectin was found to be absent in skin and cultured keratinocytes from an MD-EBS patient by immunofluorescence and immunoprecipitation, suggesting that plectin is a candidate gene/protein system for MD-EBS mutation. The 14800-bp human plectin cDNA was cloned and sequenced. The predicted 518-kD polypeptide has homology to the actin-binding domain of the dystrophin family at the amino terminus, a central rod domain, and homology to the intermediate filament-associated protein desmoplakin at the carboxyl terminus. The corresponding human gene (PLEC1), consisting of 33 exons spanning >26 kb of genomic DNA was cloned, sequenced, and mapped to chromosomal band 8q24. Homozygosity by descent was observed in the consanguineous MD-EBS family with intragenic plectin polymorphisms. Direct sequencing of PCR-amplified plectin cDNA from the patient's keratinocytes revealed a homozygous 8-bp deletion in exon 32 causing a frameshift and a premature termination codon 42 bp downstream. The clinically unaffected parents of the proband were found to be heterozygous carriers of the mutation. These results establish the molecular basis of MD-EBS in this family and clearly demonstrate the important structural role for plectin in cytoskeleton-membrane adherence in both skin and muscle.
McLean
W H
WH
Department of Anatomy and Physiology, Medical Sciences Institute, University of Dundee, UK.
Pulkkinen
L
L
Smith
F J
FJ
Rugg
E L
EL
Lane
E B
EB
Bullrich
F
F
Burgeson
R E
RE
Amano
S
S
Hudson
D L
DL
Owaribe
K
K
McGrath
J A
JA
McMillan
J R
JR
Eady
R A
RA
Leigh
I M
IM
Christiano
A M
AM
Uitto
J
J
D000199:Actins / Q000378:metabolism; D000328:Adult; D000595:Amino Acid Sequence; D001483:Base Sequence; D002874:Chromosome Mapping; D002898:Chromosomes, Human, Pair 8 / Q000235:genetics; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics*; D004820:Epidermolysis Bullosa / Q000150:complications* / Q000235:genetics* / Q000473:pathology; D005260:Female; D016368:Frameshift Mutation; D006801:Humans; D007381:Intermediate Filament Proteins / Q000172:deficiency* / Q000235:genetics*; D008297:Male; D008969:Molecular Sequence Data; D009136:Muscular Dystrophies / Q000150:complications* / Q000235:genetics* / Q000473:pathology; D010375:Pedigree; D010641:Phenotype; D051190:Plectin; D016133:Polymerase Chain Reaction
D000199:Actins; D018076:DNA, Complementary; D007381:Intermediate Filament Proteins; C495332:PLEC protein, human; D051190:Plectin