Colocalization of kindlin-1, kindlin-2, and migfilin at keratinocyte focal adhesion and relevance to the pathophysiology of Kindler syndrome.
Kindler syndrome (KS) results from pathogenic loss-of-function mutations in the KIND1 gene, which encodes kindlin-1, a focal adhesion and actin cytoskeleton-related protein. How and why abnormalities in kindlin-1 disrupt keratinocyte cell biology in KS, however, is not yet known. In this study, we identified two previously unreported binding proteins of kindlin-1: kindlin-2 and migfilin. Co-immunoprecipitation and confocal microscopy studies show that these three proteins bind to each other and colocalize at focal adhesion in HaCaT cells and normal human keratinocytes. Moreover, loss-of-function mutations in KIND1 result in marked variability in kindlin-1 immunolabeling in KS skin, which is mirrored by similar changes in kindlin-2 and migfilin immunoreactivity. Kindlin-1, however, may function independently of kindlin-2 and migfilin, as loss of kindlin-1 expression in HaCaT keratinocytes by RNA interference and in KS keratinocytes does not affect KIND2 or FBLIM1 (migfilin) gene expression or kindlin-2 and migfilin protein localization. In addition to identifying protein-binding partners for kindlin-1, this study also highlights that KIND1 gene expression and kindlin-1 protein labeling are not always reduced in KS, findings that are relevant to the accurate laboratory diagnosis of this genodermatosis by skin immunohistochemistry.
Genetic Skin Disease Group, St John's Institute of Dermatology, Division of Genetics and Molecular Medicine, King's College London, London, UK.
J E
JE
Lai-Cheong
S
S
Ussar
K
K
Arita
I R
IR
Hart
J A
JA
McGrath
D001706:Biopsy; D001768:Blister / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D022001:Focal Adhesions / Q000378:metabolism* / Q000473:pathology; D005786:Gene Expression Regulation; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism* / Q000473:pathology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation / Q000235:genetics / Q000502:physiology; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D010787:Photosensitivity Disorders / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D012867:Skin / Q000378:metabolism / Q000473:pathology; D012873:Skin Diseases, Genetic / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D013577:Syndrome
D015815:Cell Adhesion Molecules; D003598:Cytoskeletal Proteins; C473794:FBLIM1 protein, human; C475301:FERMT1 protein, human; C477322:FERMT3 protein, human; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D012333:RNA, Messenger