Loss-of-Function Mutations in SERPINB8 Linked to Exfoliative Ichthyosis with Impaired Mechanical Stability of Intercellular Adhesions

Manuela Pigors, Ofer Sarig, Lisa Heinz, Vincent Plagnol, Judith Fischer, Janan Mohamad, Natalia Malchin, Shefali Rajpopat, Monia Kharfi, Giles G. Lestringant, Eli Sprecher, David P. Kelsell, Diana C. Blaydon

Research output: Contribution to journalArticlepeer-review

Abstract

SERPINS comprise a large and functionally diverse family of serine protease inhibitors. Here, we report three unrelated families with loss-of-function mutations in SERPINB8 in association with an autosomal-recessive form of exfoliative ichthyosis. Whole-exome sequencing of affected individuals from a consanguineous Tunisian family and a large Israeli family revealed a homozygous frameshift mutation, c.947delA (p.Lys316Serfs90), and a nonsense mutation, c.850C>T (p.Arg284), respectively. These two mutations are located in the last exon of SERPINB8 and, hence, would not be expected to lead to nonsense-mediated decay of the mRNA; nonetheless, both mutations are predicted to lead to loss of the reactive site loop of SERPINB8, which is crucial for forming the SERPINB8-protease complex. Using Sanger sequencing, a homozygous missense mutation, c.2T>C (p.Met1?), predicted to result in an N-terminal truncated protein, was identified in an additional family from UAE. Histological analysis of a skin biopsy from an individual homozygous for the variant p.Arg284 showed disadhesion of keratinocytes in the lower epidermal layers plus decreased SERPINB8 levels compared to control. In vitro studies utilizing siRNA-mediated knockdown of SERPINB8 in keratinocytes demonstrated that in the absence of the protein, there is a cell-cell adhesion defect, particularly when cells are subjected to mechanical stress. In addition, immunoblotting and immunostaining revealed an upregulation of desmosomal proteins. In conclusion, we report mutations in SERPINB8 that are associated with exfoliative ichthyosis and provide evidence that SERPINB8 contributes to the mechanical stability of intercellular adhesions in the epidermis.

Original languageEnglish
Pages (from-to)430-436
Number of pages7
JournalAmerican Journal of Human Genetics
Volume99
Issue number2
DOIs
StatePublished - 4 Aug 2016
Externally publishedYes

Fingerprint

Dive into the research topics of 'Loss-of-Function Mutations in SERPINB8 Linked to Exfoliative Ichthyosis with Impaired Mechanical Stability of Intercellular Adhesions'. Together they form a unique fingerprint.

Cite this