title: Localization of the TIG3 transglutaminase interaction domain and demonstration that the amino-terminal region is required for TIG3 function as a keratinocyte differentiation regulator.
abstract: Tazarotene-induced gene 3 (TIG3) regulates keratinocyte terminal differentiation by activating type I transglutaminase (TG1). TIG3 consists of an amino-terminal (N-terminal) segment, that encodes several conserved motifs, and a carboxy-terminal (C-terminal) membrane-anchoring domain. By producing a series of truncation mutants that remove segments of the N-terminal region, and monitoring the ability of each mutant to co-precipitate TG1, function as a TG1 substrate, or functionally localize with TG1 in cells, we show that the TIG3 domain that interacts with TG1 is located within a TIG3 segment spanning amino acids 112-164. Although they bind TG1, TIG3 mutants lacking the conserved N-terminal region drive apoptosis-like cell death characterized by cell rounding, membrane blebbing, cytochrome c release, procaspase-3 and poly(ADP-ribose)polymerase (PARP) cleavage, and reduced p53 and p21 levels. Compared with TIG3, these truncated mutants have an increased tendency to associate with membranes. A mutant lacking the C-terminal membrane-anchoring domain is inactive. These findings suggest that TIG3 interaction with TG1 does not require the N-terminal conserved domains, that the TIG3 N-terminal region is required for TIG3-dependent keratinocyte differentiation, that its removal converts TIG3 into a proapoptotic protein, and that this change in action of TIG3 is associated with an intracellular redistribution.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
authors.forename: Ralph
authors.initials: R
authors.lastname: Jans
authors.forename: Michael T
authors.initials: MT
authors.lastname: Sturniolo
authors.forename: Richard L
authors.initials: RL
authors.lastname: Eckert
mesh_terms: D000217:Acyltransferases / Q000235:genetics; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D019556:COS Cells; D002103:Cadaverine / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D045304:Cytochromes c / Q000378:metabolism; D000078404:Epidermal Cells; D005453:Fluorescence; D006801:Humans; D015603:Keratinocytes / Q000166:cytology* / Q000201:enzymology*; D054878:Lipoylation; D008970:Molecular Weight; D016296:Mutagenesis; D017434:Protein Structure, Tertiary; D018168:Receptors, Retinoic Acid / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014162:Transfection; D011503:Transglutaminases / Q000378:metabolism
chemical_list: C437968:PLAAT4 protein, human; D018168:Receptors, Retinoic Acid; D045304:Cytochromes c; D000217:Acyltransferases; C056942:lecithin-retinol acyltransferase; D011503:Transglutaminases; C105804:transglutaminase 1; D002103:Cadaverine