Characterization and functional analysis of laminin isoforms in human bone marrow

• Published in: Blood 2000-12, Vol.96 (13), p.4194-4203
• Main Authors: Siler, Ulrich, Seiffert, Martina, Puch, Sabine, Richards, Allan, Torok-Storb, Beverly, Müller, Claudia A., Sorokin, Lydia, Klein, Gerd
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Blotting, Western; Bone Marrow - chemistry; Bone Marrow Cells - chemistry; Cell Adhesion - drug effects; Cells, Cultured; Combined treatment; Culture Media, Conditioned; Hematopoietic Stem Cells - cytology; Hematopoietic Stem Cells - drug effects; Hematopoietic Stem Cells - metabolism; Humans; Immune Sera; Integrin beta1 - immunology; Integrin beta1 - metabolism; Laminin - chemistry; Laminin - genetics; Laminin - isolation & purification; Laminin - pharmacology; Medical sciences; Mitosis - drug effects; Multigene Family; Protein Isoforms - chemistry; Protein Isoforms - genetics; Protein Isoforms - isolation & purification; Protein Isoforms - pharmacology; Protein Subunits; Reverse Transcriptase Polymerase Chain Reaction; Stromal Cells - chemistry; Treatment. General aspects; Tumors
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V96.13.4194

Laminins are a family of disulfide-linked heterotrimeric proteins consisting of 3 different subunits termed α, β, and γ chains. Combinations of 11 characterized laminin subunits (α1-α5, β1-β3, and γ1-γ3) generate at least 12 laminin isoforms, which can serve different functions. Although expression of laminin in the hematopoietic microenvironment has been known for many years, the nature of the laminin isoforms present in the human bone marrow is poorly characterized. The present study attempts to clarify this issue. Reverse transcriptase–polymerase chain reaction analysis of human bone marrow stromal cells suggested the expression of many laminin isoforms in the marrow. Northern blot and immunoblot analysis, however, showed that laminin-8/9 and laminin-10/11 are the most abundant laminin isoforms synthesized by human bone marrow stromal cells. Other isoforms, if present, certainly play a minor role in the hematopoietic microenvironment. Functionally, laminin-10/11 preparations showed strong adhesive interactions with human CD34+ cell lines. Antibodies against the β1 integrin subunit inhibited these interactions. Other laminin isoforms, especially laminin-1 and laminin-2/4, showed only weak or no adhesive interactions with the hematopoietic cell lines tested, explaining former negative results. In addition to its adhesion-mediating properties, laminin-10/11 preparations also showed a mitogenic activity for human hematopoietic progenitor cells. Taken together, these data suggest that laminin in the bone marrow plays a hitherto unexpected important function in the development of hematopoietic progenitor cells.