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.
Taresa
E
E
Department of Biochemistry, University Medical School, Debrecen, Hungary.
Kedei
N
N
Thomazy
V
V
Fesus
L
L
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