Carboxyl terminus of Plakophilin-1 recruits it to plasma membrane, whereas amino terminus recruits desmoplakin and promotes desmosome assembly.
Plakophilins are armadillo repeat-containing proteins, initially identified as desmosomal plaque proteins that have subsequently been shown to also localize to the nucleus. Loss of plakophilin-1 is the underlying cause of ectodermal dysplasia/skin fragility syndrome, and skin from these patients exhibits desmosomes that are reduced in size and number. Thus, it has been suggested that plakophilin-1 plays an important role in desmosome stability and/or assembly. In this study, we used a cell culture system (A431DE cells) that expresses all of the proteins necessary to assemble a desmosome, except plakophilin-1. Using this cell line, we sought to determine the role of plakophilin-1 in de novo desmosome assembly. When exogenous plakophilin-1 was expressed in these cells, desmosomes were assembled, as assessed by electron microscopy and immunofluorescence localization of desmoplakin, into punctate structures. Deletion mutagenesis experiments revealed that amino acids 686-726 in the carboxyl terminus of plakophilin-1 are required for its localization to the plasma membrane. In addition, we showed that amino acids 1-34 in the amino terminus were necessary for subsequent recruitment of desmoplakin to the membrane and desmosome assembly.
Sobolik-Delmaire
Tammy
T
Department of Oral Biology, University of Nebraska Medical Center College of Dentistry and Nebraska Center for Cellular Signaling, Omaha, Nebraska 68138.
Katafiasz
Dawn
D
Department of Oral Biology, University of Nebraska Medical Center College of Dentistry and Nebraska Center for Cellular Signaling, Omaha, Nebraska 68138.
Wahl
James K
JK
Department of Oral Biology, University of Nebraska Medical Center College of Dentistry and Nebraska Center for Cellular Signaling, Omaha, Nebraska 68138. Electronic address: jwahl@unmc.edu.
D000595:Amino Acid Sequence; D002118:Calcium / Q000737:chemistry; D002460:Cell Line; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D051180:Desmoplakins / Q000737:chemistry*; D003896:Desmosomes / Q000378:metabolism; D017353:Gene Deletion; D006801:Humans; D008969:Molecular Sequence Data; D051191:Plakophilins / Q000737:chemistry* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
D051180:Desmoplakins; D051191:Plakophilins; D002118:Calcium