BMP-6 inhibits human bone marrow B lymphopoiesis--upregulation of Id1 and Id3.
OBJECTIVE
In mammals, factors produced by bone marrow (BM) stromal cells are instrumental in orchestrating the developmental process of B lymphocytes. Bone morphogenetic proteins (BMPs) are multifunctional cytokines previously found to regulate hematopoietic stem cells. In the present study, we have explored the role of BMP-6 in human B progenitor cells.


METHODS
In vitro B lymphopoiesis of CD10(+) B progenitor cells from human BM was evaluated in the presence or absence of BMP-6 in short- or long-term coculture on MS-5 stromal cells, by tracking CFSE-labeled CD10(+) B progenitor cells or by quantification of CD19(+) cells. DNA synthesis in the pre-B cell line Nalm-6 was measured by (3)H-thymidine incorporation. BMP-6-induced phosphorylation of Smad1/5/8 was determined by Western blot analysis, whereas elevation of Id1-Id4 mRNA levels and basal BMP-6 mRNA levels were measured by real-time and conventional RT-PCR, respectively.


RESULTS
By in vitro coculture of CD10(+) B progenitor cells or monoculture of Nalm-6 cells, we found that BMP-6 inhibited B lymphopoiesis by impeding cell proliferation. Furthermore, in CD10(+) B progenitors as well as in Nalm-6 cells, BMP-6 rapidly induced phosphorylation of Smad1/5/8, followed by an upregulation of Id1 and Id3 mRNA levels. Finally, we demonstrated that human bone marrow stromal cells express BMP-6 mRNA whereas B progenitor cells did not.


CONCLUSIONS
We suggest that BMP-6, produced by the BM, may participate to fine-tune the balance between proliferation, apoptosis, and differentiation in human B progenitor cells during BM B lymphopoiesis.
Kersten
Christian
C
Department of Immunology, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway. christian.kersten@sshf.no
Dosen
Guri
G
Myklebust
June H
JH
Sivertsen
Einar A
EA
Hystad
Marit E
ME
Smeland
Erlend B
EB
Rian
Edith
E
D001402:B-Lymphocytes / Q000187:drug effects* / Q000378:metabolism; D001854:Bone Marrow Cells / Q000187:drug effects* / Q000378:metabolism; D055418:Bone Morphogenetic Protein 6; D019485:Bone Morphogenetic Proteins / Q000096:biosynthesis / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D018920:Coculture Techniques; D005786:Gene Expression Regulation; D006801:Humans; D051798:Inhibitor of Differentiation Protein 1 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D051796:Inhibitor of Differentiation Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D038041:Lymphopoiesis / Q000187:drug effects* / Q000502:physiology; D009363:Neoplasm Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D051898:Smad1 Protein / Q000187:drug effects / Q000378:metabolism; D051902:Smad5 Protein / Q000187:drug effects / Q000378:metabolism; D051904:Smad8 Protein / Q000187:drug effects / Q000378:metabolism; D017154:Stromal Cells; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
C525816:BMP6 protein, human; D055418:Bone Morphogenetic Protein 6; D019485:Bone Morphogenetic Proteins; C497453:ID1 protein, human; D051798:Inhibitor of Differentiation Protein 1; D051796:Inhibitor of Differentiation Proteins; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; C497399:SMAD1 protein, human; C497797:SMAD5 protein, human; C107514:SMAD9 protein, human; D051898:Smad1 Protein; D051902:Smad5 Protein; D051904:Smad8 Protein; C075640:ID3 protein, human