Inability of keratinocytes lacking their specific transglutaminase to form cross-linked envelopes: absence of envelopes as a simple diagnostic test for lamellar ichthyosis.
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 Ca2+. 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 disease by a simple test for cross-linked envelopes.
Jeon
S
S
Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
Djian
P
P
Green
H
H
D002452:Cell Count; D002465:Cell Movement; D006801:Humans; D017490:Ichthyosis, Lamellar / Q000473:pathology*; D015603:Keratinocytes / Q000201:enzymology* / Q000473:pathology*; D009154:Mutation; D012333:RNA, Messenger / Q000032:analysis; D011503:Transglutaminases / Q000502:physiology*
D012333:RNA, Messenger; D011503:Transglutaminases