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Hidradenitis suppurativa: haploinsufficiency of gamma‐secretase components does not affect gamma‐secretase enzyme activity in vitro
Author(s) -
Pink A.E.,
Dafou D.,
Desai N.,
Holmes O.,
Hobbs C.,
Smith C.H.,
Mortimer P.,
Simpson M.A,
Trembath R.C.,
Barker J.N.
Publication year - 2016
Publication title -
british journal of dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.304
H-Index - 179
eISSN - 1365-2133
pISSN - 0007-0963
DOI - 10.1111/bjd.14621
Subject(s) - hidradenitis suppurativa , gamma secretase , haploinsufficiency , in vitro , affect (linguistics) , enzyme , medicine , chemistry , pathology , biochemistry , psychology , disease , phenotype , communication , gene
DEAR EDITOR, Hidradenitis suppurativa (HS) is a chronic inflammatory dermatosis that presents with nodules, cysts, abscesses and sinus tracts in apocrine gland-bearing areas. It is thought to occur secondarily to follicular occlusion, has been associated with smoking and obesity and may be inherited in an autosomal dominant manner in a minority of cases. Heterozygous mutations in the gamma-secretase genes PSENEN, PSEN1 and NCSTN underlie 0–7% of cases. Gamma-secretase is an intramembranous protease complex comprised of nicastrin, presenilin, presenilin enhancer (PEN)-2 and anterior pharynx defective (APH)1. It is involved in regulated intramembranous proteolysis and the subsequent clearance of substrates from cell membranes (endopeptidase and carboxypeptidase activity). The functional effects of gammasecretase gene mutations in HS are yet to be elicited. It was hypothesized that two previously reported mutations (NCSTN c.1125 + 1 G>A and PSENEN c.66_67insG) would affect the corresponding RNA and protein expression and function and affect gamma-secretase enzyme activity. This study was approved by the London Stanmore Research Ethics Committee (11/LO/0966) and conducted in accordance with the Declaration of Helsinki principles. Diagnostic criteria are detailed in Appendix S1 (see Supporting Information). Two 6-mm axillary skin biopsies (affected and unaffected skin) were taken from two mutation-positive individuals and three healthy volunteers for immunohistochemistry and cell culture. DNA, RNA and protein were extracted from primary human fibroblasts and analysed via agarose electrophoresis, Sanger sequencing, gene expression assays and immunoblotting. Gamma-secretase enzyme activity