Increased expression of colonic Wnt9A through Sp1-mediated transcriptional effects involving arylsulfatase B, chondroitin 4-sulfate, and galectin-3.
In cultured human colonic epithelial cells and mouse colonic tissue, exposure to the common food additive carrageenan leads to inflammation, activation of Wnt signaling, increased Wnt9A expression, and decline in the activity of the enzyme arylsulfatase B (ARSB; N-acetylgalactosamine-4-sulfatase). In this study, the novel transcriptional mechanism by which carrageenan and decline in ARSB increase Wnt9A expression in NCM460 and HT-29 human colonic epithelial cells and in mouse colon is presented. Increased expression of Wnt9A has been associated with multiple malignancies, including colon carcinoma, and with ectodermal and mesoendodermal morphogenesis. When ARSB activity was reduced by siRNA or by exposure to carrageenan (1 μg/ml for 24 h), degradation of chondroitin 4-sulfate (C4S) was inhibited, leading to accumulation of more highly sulfated C4S, which binds less galectin-3, a β-galactoside-binding protein. Nuclear galectin-3 increased and mediated increased binding of Sp1 to the Sp1 consensus sequence in the Wnt9A promoter, shown by oligonucleotide-binding assay and by chromatin immunoprecipitation assay. When galectin-3 was silenced, the increases in Sp1 binding to the Wnt9A promoter and in Wnt9A expression, which followed carrageenan or ARSB silencing, were inhibited. Mithramycin A, a specific inhibitor of Sp1 oligonucleotide binding, and Sp1 siRNA blocked the carrageenan- and ARSB siRNA-induced increases in Wnt9A expression. These studies reveal how carrageenan exposure can lead to transcriptional events in colonic epithelial cells through decline in arylsulfatase B activity, with subsequent impact on C4S, galectin-3, Sp1, and Wnt9A and can exert significant effects on Wnt-initiated signaling and related vital cell processes.
From the Department of Medicine, University of Illinois at Chicago Chicago, Illinois 60612 and Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois 60612.
Sumit
S
Bhattacharyya
From the Department of Medicine, University of Illinois at Chicago Chicago, Illinois 60612 and Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois 60612.
Leo
L
Feferman
From the Department of Medicine, University of Illinois at Chicago Chicago, Illinois 60612 and Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois 60612 jkt@uic.edu.
Joanne K
JK
Tobacman
D000818:Animals; D001798:Blood Proteins; D002351:Carrageenan / Q000494:pharmacology; D002460:Cell Line; D002809:Chondroitin Sulfates / Q000235:genetics / Q000378:metabolism*; D003106:Colon / Q000166:cytology / Q000378:metabolism*; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D037502:Galectin 3 / Q000235:genetics / Q000378:metabolism*; D037161:Galectins; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007413:Intestinal Mucosa / Q000166:cytology / Q000378:metabolism*; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains; D020051:N-Acetylgalactosamine-4-Sulfatase / Q000235:genetics / Q000378:metabolism*; D008926:Plicamycin / Q000031:analogs & derivatives / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000502:physiology; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology; D051153:Wnt Proteins / Q000096:biosynthesis* / Q000235:genetics
D001798:Blood Proteins; D037502:Galectin 3; D037161:Galectins; C428445:LGALS3 protein, human; C485095:Lgals3 protein, mouse; D016329:Sp1 Transcription Factor; C110670:WNT9A protein, human; D051153:Wnt Proteins; C486388:Wnt9a protein, mouse; D002351:Carrageenan; D002809:Chondroitin Sulfates; C066851:mithramycin A; D020051:N-Acetylgalactosamine-4-Sulfatase; C581941:ARSB protein, human; D008926:Plicamycin
Animal Model; Cancer Biology; Carrageenan; Chondroitin Sulfate; Galectin; Specificity Protein 1 (Sp1); Wnt