Laminin isoforms in human embryonic stem cells: synthesis, receptor usage and growth support.
To reveal the functional intrinsic niche of human embryonic stem cells (hESC) we examined the production of basement membrane (BM) proteins and the presence of their receptors in feeder-free cell culture conditions. In addition, we investigated binding of hESCs to purified human BM proteins and identified the receptors mediating these contacts. Also, we tested whether purified human laminin (Lm) isoforms have a role in hESC self-renewal and growth in short-term cultures. The results show that hESCs synthesize Lm alpha(1) and Lm alpha(5) chains together with Lm beta(1) and gamma(1) chains suggesting the production of Lms-111 and -511 into the culture medium and deposits on cells. hESCs contain functionally important integrin (Int) subunits, Int beta(1), alpha(3), alpha(6), alpha(5), beta(5) and alpha(V), as well as the Lm alpha(5) receptor, Lutheran (Lu) glycoprotein and its truncated form, basal cell adhesion molecule (B-CAM). In cell adhesion experiments, Int beta(1) was crucial for adhesion to most of the purified human BM proteins. Lu/B-CAM mediated adhesion to Lm-511 together with Int alpha(3)beta(1), and was essential for the adhesion of hESCs to embryonic feeder cells. Adhesion to Lm-411 was mediated by Int alpha(6)beta(1). Lm-511 supported hESC growth in defined medium equally well as Matrigel. These results provide consequential information of the biological role of BM in hESCs, warranting further investigation of BM biology of human pluripotent stem cells.
Vuoristo
Sanna
S
Biomedicum Stem Cell Center, University of Helsinki, Helsinki, Finland.|Hospital for Children and Adolescents, University of Helsinki, Helsinki, Finland.
Virtanen
Ismo
I
Institute of Biomedicine/Anatomy, University of Helsinki, Helsinki, Finland.
Takkunen
Minna
M
Institute of Biomedicine/Anatomy, University of Helsinki, Helsinki, Finland.
Palgi
Jaan
J
Biomedicum Stem Cell Center, University of Helsinki, Helsinki, Finland.
Kikkawa
Yamato
Y
Laboratory of Clinical Biochemistry, School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, Japan.
Rousselle
Patricia
P
Institut de Biologie et Chimie des Protéines, Unité Mixte de Recherche, Institut Fédératif de Recherche BioSciences Lyon-Gerland, Lyon, France.
Sekiguchi
Kiyotoshi
K
Laboratory of Extracellular Matrix Biochemistry, Institute for Protein Research, Osaka University, Suita, Osaka, Japan.
Tuuri
Timo
T
Biomedicum Stem Cell Center, University of Helsinki, Helsinki, Finland.
Otonkoski
Timo
T
Biomedicum Stem Cell Center, University of Helsinki, Helsinki, Finland.|Hospital for Children and Adolescents, University of Helsinki, Helsinki, Finland.
D002478:Cells, Cultured; D003470:Culture Media; D053595:Embryonic Stem Cells / Q000378:metabolism*; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry; D007797:Laminin / Q000378:metabolism*; D020033:Protein Isoforms / Q000378:metabolism*; D017474:Receptors, Laminin / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D003470:Culture Media; D007797:Laminin; D020033:Protein Isoforms; D017474:Receptors, Laminin