title: Collagen gel overlay induces apoptosis of polarized cells in cultures: disoriented cell death.
abstract: In this study, we attempted to investigate the response of polarized cells to inappropriate interaction with the extracellular matrix. Cell lines of epithelial [Madin-Darby canine kidney (MDCK) and LLC-PK1], endothelial [bovine aortic endothelial cells (BAEC)], and mesenchymal (ESK-4 and NIH/3T3) origins were employed. With collagen gel overlay, MDCK cells underwent membrane remodeling and gradually developed lumen formation within 24 h. Apoptosis could also be observed following cell remodeling. The ratio of apoptosis was enhanced from 12.1 +/- 2.4% within 24 h to 58.4 +/- 9.8% at day 3, and finally the monolayer was disintegrated. Collagen gel overlay-induced apoptosis was not a result of physical stress, since agarose gel overlay did not induce any morphological alterations. All epithelial and endothelial cells examined developed apoptosis in response to collagen overlay. In contrast, collagen overlay did not affect growth of fibroblasts at all, although their growth under agarose gel was slightly hindered due to physical stress. Collagen overlay-induced apoptosis seems to be a unique phenomenon for polarized cells and thus is defined as "disoriented cell death." Furthermore, anti-alpha2-integrin antibody could abolish collagen overlay-induced morphological changes and apoptosis in MDCK cells, indicating that signals through alpha2-integrin on the apical membrane are required for disoriented cell death. Finally, Bcl-2 overexpression prolonged survival of MDCK cells in response to collagen overlay, but these cells eventually developed apoptosis due to downregulation of Bcl-2 protein. These findings indicate that inappropriate cell-matrix interaction results in apoptosis, which may account for cell death mechanisms during developmental processes or under pathological conditions.
authors.affiliation: Department of Physiology, National Cheng Kung University Medical College, Tainan, Taiwan, Republic of China.
authors.forename: M J
authors.initials: MJ
authors.lastname: Tang
authors.forename: J J
authors.initials: JJ
authors.lastname: Hu
authors.forename: H H
authors.initials: HH
authors.lastname: Lin
authors.forename: W T
authors.initials: WT
authors.lastname: Chiu
authors.forename: S T
authors.initials: ST
authors.lastname: Jiang
mesh_terms: D016475:3T3 Cells; D000818:Animals; D001011:Aorta; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002417:Cattle; D016923:Cell Death; D002455:Cell Division; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure; D016764:Cell Polarity / Q000502:physiology*; D002478:Cells, Cultured; D003094:Collagen / Q000494:pharmacology*; D004285:Dogs; D004730:Endothelium, Vascular / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D004847:Epithelial Cells / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D005782:Gels; D007668:Kidney; D007700:Kinetics; D008648:Mesoderm / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D051379:Mice
chemical_list: D005782:Gels; D003094:Collagen