The Wnt signaling inhibitor dickkopf-1 is required for reentry into the cell cycle of human adult stem cells from bone marrow.
Adult human mesenchymal stem cells from bone marrow stroma (hMSCs) differentiate into numerous mesenchymal tissue lineages and are attractive candidates for cell and gene therapy. When early passage hMSCs are plated or replated at low density, the cultures display a lag phase of 3-5 days, a phase of rapid exponential growth, and then enter a stationary phase without the cultures reaching confluence. We found that as the cultures leave the lag phase, they secrete high levels of dickkopf-1 (Dkk-1), an inhibitor of the canonical Wnt signaling pathway. The addition of recombinant Dkk-1 toward the end of the lag period increased proliferation and decreased the cellular concentration of beta-catenin. The addition of antibodies to Dkk-1 in the early log phase decreased proliferation. Also, expression of Dkk-1 in hMSCs decreased during cell cycle arrest induced by serum starvation. The results indicated that high levels of Dkk-1 allow the cells to reenter the cell cycle by inhibiting the canonical Wnt/beta-catenin signaling pathway. Since antibodies to Dkk-1 also increased the lag phase of an osteosarcoma line that expressed the gene, Dkk-1 may have a similar role in some other cell systems.
Gregory
Carl A
CA
Center for Gene Therapy, Tulane University Health Sciences Center, New Orleans, Louisiana 70112, USA.
Singh
Harpreet
H
Perry
Anthony S
AS
Prockop
Darwin J
DJ
D000328:Adult; D000595:Amino Acid Sequence; D015153:Blotting, Western; D001854:Bone Marrow Cells / Q000378:metabolism*; D002453:Cell Cycle; D002455:Cell Division; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D017077:Culture Media, Conditioned / Q000494:pharmacology; D003598:Cytoskeletal Proteins / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007150:Immunohistochemistry; D036341:Intercellular Signaling Peptides and Proteins; D008648:Mesoderm / Q000378:metabolism; D008875:Middle Aged; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D011506:Proteins / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism; D013997:Time Factors; D015534:Trans-Activators / Q000378:metabolism; D014158:Transcription, Genetic; D014357:Trypsin / Q000494:pharmacology; D051153:Wnt Proteins; D029961:Zebrafish Proteins; D051176:beta Catenin
C495270:CTNNB1 protein, human; D017077:Culture Media, Conditioned; D003598:Cytoskeletal Proteins; C501126:DKK1 protein, human; D036341:Intercellular Signaling Peptides and Proteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D015534:Trans-Activators; D051153:Wnt Proteins; D029961:Zebrafish Proteins; D051176:beta Catenin; C501128:dkk1b protein, zebrafish; D014357:Trypsin