Inability of keratinocytes lacking their specific transglutaminase to form cross-linked envelopes: Absence of envelopes as a simple diagnostic test for lamellar ichthyosis

Abstract

Epidermal keratinocytes, late in their terminal differentiation, form cross-linked envelopes resistant to ionic detergent and reducing agent. Because the cross-linking process is catalyzed by the keratinocyte transglutaminase, the absence of active transglutaminase should result in failure of the keratinocyte to form a cross-linked envelope. Three keratinocyte strains bearing mutations in the keratinocyte transglutaminase were examined: two contained no detectable transglutaminase mRNA and none contained active enzyme. All three were unable to form cross-linked envelopes, either spontaneously in stratified cultures or upon induction with Ca 2؉ . Although stratum corneum of normal humans and scales from patients with different ichthyotic diseases contain cross-linked envelopes, those from patients with transglutaminase-negative lamellar ichthyosis do not. Therefore, the disease due to the absence of transglutaminase may be readily distinguished from other ichthyotic diseases by a simple test for cross-linked envelopes.

Revised nomenclature and classification of inherited ichthyoses: Results of the First Ichthyosis Consensus Conference in Sorèze 2009

“…225,226 Alternatively, superficial SC material can be subjected to a SDS heating test that visualizes absent cross-linked envelopes in TGase-1 deficiency. 227 There are special useful analyses given in Tables IV to XII. For instance, steroid sulfatase deficiency underlying RXLI can be demonstrated by reduced arylsulfatase-C activity of leukocytes, or can readily be diagnosed by the widely available fluorescent in situ hybridization test for the STS gene region, because more than 90% of the cases are caused by a gene deletion.…”

Filaggrin Genotype in Ichthyosis Vulgaris Predicts Abnormalities in Epidermal Structure and Function

“…After centrifuging (2000 ϫ g for 5 minutes), corneocyte suspensions were assessed by light microscopy in the Nomarsky mode. 50 To assess corneocyte fragility under stressed conditions, the pellet was resuspended in 2% SDS and subjected to ultrasound (U200S control, amplitude 20%, cycle 0.1; IKA Labortechnik, Staufen, Germany ). SC cohesion was assessed as protein removed per D-Squame (CuDerm Corporation, Dallas, TX), applied sequentially to the test area for about 3 seconds, removed with a forceps, and stored in a glass scintillation vial at 4°C.…”

The Clinical and Morphologic Features of Nonepidermolytic Ichthyosis in the Golden Retriever

“…The scales were placed in 10 ml Dulbecco's Minimum Essential Medium plus 2% 2-mercaptoethanol and 2% sodium dodecyl sulfate, boiled for 10 minutes, and vortexed for 10 minutes, and envelopes were counted via a hemocytometer under the light microscope. 23 …”