C-terminally truncated kindlin-1 leads to abnormal adhesion and migration of keratinocytes

Background The Kindler syndrome (KS) protein kindlin-1 is a member of a protein complex that links cortical actin to integrins on the surface of basal keratinocytes. Loss of kindlin-1 leads to abnormalities of cell adhesion and motility, and to skin blistering and progressive poikiloderma as clinical symptoms.

Objectives Here we investigated a severely affected patient, disclosed the mutation that caused the disease and delineated its biological consequences.

Methods Mutation screening of the kindlin-1 gene, KIND1 (now called FERMT1), was performed with polymerase chain reaction (PCR) amplification of all exons and sequencing. Mutated kindlin-1 was characterized by reverse transcriptase (RT)-PCR and immunoblotting, and genotype–phenotype correlations were analysed using immunohistochemical staining of skin biopsies and keratinocytes from the patient’s skin. Cell adhesion and motility were assessed with functional tests.

Results We disclosed a splice site mutation in the first position of intron 13 of the FERMT1 gene, which caused skipping of exon 13. The short transcript partially escaped nonsense-mediated mRNA decay and was translated into a truncated protein.

Conclusion A C-terminally truncated kindlin-1 in keratinocytes could not function correctly even if it were expressed.