title: Collagen I regulates the self-renewal of mouse embryonic stem cells through α2β1 integrin- and DDR1-dependent Bmi-1.
abstract: Adhesion of cells to extracellular matrix (ECM) influences vital aspects of anchorage-dependent cell behavior including survival, proliferation, and differentiation. However, the role of collagen I in mouse embryonic stem cells (mESCs) is not well-known. Therefore, in the present study we examined the effect of collagen I on mESC self-renewal and related signal pathways. Collagen I (10 µg/ml) maintained mESCs in an undifferentiated state (Nanog, OCT4, and SSEA-1) and did not affect differentiation (GATA4, Tbx5, Fgf5, and Cdx2) in the presence of leukemia inhibitory factor (LIF). Treatment with collagen I bound both α2β1 integrin and discoidin domain receptor 1 (DDR1), and stimulated intracellular signaling pathways. Collagen I-bound α2β1 integrin increased integrin-linked kinase (ILK) phosphorylation, cleaved Notch protein expression in the nuclear fraction, and Gli-1 mRNA expression. In addition, collagen I-bound DDR1 increased GTP-bound Ras, phosphoinositide 3-kinase (PI3K) p85α catalytic subunit protein expression, and Akt and ERK phosphorylation. Importantly, collagen I increased Bmi-1 protein expression in the nucleus which was blocked by small interfering RNA (siRNA) specific for Gli-1 and ERK, showing that parallel pathways of integrins and DDR1 merge at Bmi-1. Furthermore, collagen I-induced p16 decrease and p-Rb increase were reversed by Bmi-1-specific siRNA. Moreover, Bmi-1 silencing abolished the collagen I-induced increase of proliferation indices and undifferentiation markers. These results indicate that collagen I stimulates the self-renewal of mESCs mediated by Bmi-1 through α2β1 integrin-dependent ILK, Notch, Gli-1, and DDR1-dependent Ras, PI3K/Akt, and ERK.
authors.affiliation: Department of Veterinary Physiology, College of Veterinary Medicine, Chonnam National University, Gwangju, Korea.
authors.forename: Han Na
authors.initials: HN
authors.lastname: Suh
authors.forename: Ho Jae
authors.initials: HJ
authors.lastname: Han
mesh_terms: D000818:Animals; D002448:Cell Adhesion; D018797:Cell Cycle Proteins / Q000378:metabolism; D002460:Cell Line; D049109:Cell Proliferation; D024042:Collagen Type I / Q000378:metabolism*; D000070819:Discoidin Domain Receptor 1; D053595:Embryonic Stem Cells / Q000201:enzymology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D038982:Integrin alpha2beta1 / Q000378:metabolism*; D051741:Kruppel-Like Transcription Factors / Q000378:metabolism; D051379:Mice; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D058539:Phosphatidylinositol 3-Kinase / Q000378:metabolism; D010766:Phosphorylation; D039904:Pluripotent Stem Cells / Q000201:enzymology*; D063150:Polycomb Repressive Complex 1; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D051880:Receptors, Notch / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics; D013997:Time Factors; D000071676:Zinc Finger Protein GLI1; D018631:ras Proteins / Q000378:metabolism; D000099200:Scaffold Protein ILK
chemical_list: D018797:Cell Cycle Proteins; D024042:Collagen Type I; D000070819:Discoidin Domain Receptor 1; D048049:Extracellular Signal-Regulated MAP Kinases; D038982:Integrin alpha2beta1; D051741:Kruppel-Like Transcription Factors; D009687:Nuclear Proteins; D058539:Phosphatidylinositol 3-Kinase; D063150:Polycomb Repressive Complex 1; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger; D020794:Receptor Protein-Tyrosine Kinases; D051880:Receptors, Notch; D012097:Repressor Proteins; D000071676:Zinc Finger Protein GLI1; D018631:ras Proteins; D000099200:Scaffold Protein ILK; C489421:Bmi1 protein, mouse; C498520:Gli1 protein, mouse; C083249:Ddr1 protein, mouse