An involucrin-like protein in hepatocytes serves as a substrate for tissue transglutaminase during apoptosis.
Cornified envelopes and apoptotic bodies are transglutaminase-cross-linked end-products of physiological cell death pathways. The two structures have similar amino acid composition. Involucrin has been considered as a cornified envelope precursor protein expressed specifically in terminally differentiating keratinocytes and squamous epithelia. We report the presence in hepatocytes of an involucrin-like protein which could be purified from dog liver with procedures characteristic to involucrins. When compared to purified dog esophagus involucrin, the liver protein also reacts with anti-involucrin antibodies, has the same relative molecular mass, possesses similar amino acid composition, and shows almost identical peptide mapping pattern. The involucrin-like protein is detectable by immunohistochemistry in normal and apoptotic hepatocytes, is a substrate of tissue transglutaminase, and is incorporated into cross-linked apoptotic bodies. These results suggest that there are overlapping molecular components in the two characteristic forms (cornification and apoptosis) of naturally occurring cell death.
Department of Biochemistry, University Medical School, Debrecen, Hungary.
E
E
Taresa
N
N
Kedei
V
V
Thomazy
L
L
Fesus
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D017209:Apoptosis; D002478:Cells, Cultured; D004285:Dogs; D004947:Esophagus / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008297:Male; D010449:Peptide Mapping; D011498:Protein Precursors / Q000302:isolation & purification / Q000378:metabolism*; D011506:Proteins / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats; D012867:Skin / Q000166:cytology / Q000201:enzymology*; D013379:Substrate Specificity; D011503:Transglutaminases / Q000378:metabolism*
D000596:Amino Acids; D011498:Protein Precursors; D011506:Proteins; C032253:involucrin; D011503:Transglutaminases