Collagen I regulates the self-renewal of mouse embryonic stem cells through α2β1 integrin- and DDR1-dependent Bmi-1

J Cell Physiol. 2011 Dec;226(12):3422-32. doi: 10.1002/jcp.22697.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Adhesion
  • Cell Cycle Proteins / metabolism
  • Cell Line
  • Cell Proliferation*
  • Collagen Type I / metabolism*
  • Discoidin Domain Receptor 1
  • Embryonic Stem Cells / enzymology*
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Gene Expression Regulation, Developmental
  • Integrin alpha2beta1 / metabolism*
  • Kruppel-Like Transcription Factors / metabolism
  • Mice
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Phosphatidylinositol 3-Kinase / metabolism
  • Phosphorylation
  • Pluripotent Stem Cells / enzymology*
  • Polycomb Repressive Complex 1
  • Protein Serine-Threonine Kinases / metabolism
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-akt / metabolism
  • RNA Interference
  • RNA, Messenger / metabolism
  • Receptor Protein-Tyrosine Kinases / metabolism*
  • Receptors, Notch / metabolism
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism*
  • Signal Transduction* / genetics
  • Time Factors
  • Zinc Finger Protein GLI1
  • ras Proteins / metabolism

Substances

  • Bmi1 protein, mouse
  • Cell Cycle Proteins
  • Collagen Type I
  • Gli1 protein, mouse
  • Integrin alpha2beta1
  • Kruppel-Like Transcription Factors
  • Nuclear Proteins
  • Proto-Oncogene Proteins
  • RNA, Messenger
  • Receptors, Notch
  • Repressor Proteins
  • Zinc Finger Protein GLI1
  • Polycomb Repressive Complex 1
  • integrin-linked kinase
  • Phosphatidylinositol 3-Kinase
  • Ddr1 protein, mouse
  • Discoidin Domain Receptor 1
  • Receptor Protein-Tyrosine Kinases
  • Protein Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt
  • Extracellular Signal-Regulated MAP Kinases
  • ras Proteins