Defects in mesenchymal stem cell self-renewal and cell fate determination lead to an osteopenic phenotype in <i>Bmi-1</i> null mice

Zhang, Hengwei; Ding, Jiong; Jin, Jianliang; Guo, Jian; Liu, Jingning; Karaplis, Andrew C.; Goltzman, David; Miao, Dengshun

doi:10.1359/jbmr.090812

Cited by 86 publications

(149 citation statements)

References 51 publications

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“…Recently, reduced proliferation and increased apoptosis in bone marrow MSCs were associated with upregulation of p27. (28) We measured the expression of p27, and we could clearly observe that its regulation strictly followed the expression of p21. p27 was specifically inhibited by the RUNX2 siRNA.…”

Section: Discussionmentioning

confidence: 92%

TNF-α's effects on proliferation and apoptosis in human mesenchymal stem cells depend on RUNX2 expression

Ghali

Chauveau

Hardouin

et al. 2010

Journal of Bone and Mineral Research

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RUNX2 is a bone-specific transcription factor that plays a critical role in prenatal bone formation and postnatal bone development. It regulates the expression of genes that are important in committing cells into the osteoblast lineage. There is increasing evidence that RUNX2 is involved in osteoblast proliferation. RUNX2 expression increases during osteoblast differentiation, and recent data even suggest that it acts as a proapoptotic factor. The cytokine tumor necrosis factor a (TNF-a) is known to modulate osteoblast functions in a manner that depends on the differentiation stage. TNF-a affects the rate at which mesenchymal precursor cells differentiate into osteoblasts and induces apoptosis in mature osteoblasts. Thus we sought to establish whether or not the effects of TNF-a and fetal calf serum on proliferation and apoptosis in human mesenchymal stem cells (hMSCs) were dependent on RUNX2 level and activity. We transfected hMSCs with small interfering RNAs (siRNAs) directed against RUNX2 and found that they proliferated more quickly than control hMSCs transfected with a nonspecific siRNA. This increase in proliferation was accompanied by a rise in cyclin A1, B1, and E1 expression and a decrease in levels of the cyclin inhibitor p21. Moreover, we observed that RUNX2 silencing protected hMSCs from TNF-a's antiproliferative and apoptotic effects. This protection was accompanied by the inhibition of caspase-3 activity and Bax expression. Our results confirmed that RUNX2 is a critical link between cell fate, proliferation, and growth control. This study also suggested that, depending on the osteoblasts' differentiation stage, RUNX2 may control cell growth by regulating the expression of elements involved in hormone and cytokine sensitivity. ß

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Section: Discussionmentioning

confidence: 92%

TNF-α's effects on proliferation and apoptosis in human mesenchymal stem cells depend on RUNX2 expression

Ghali

Chauveau

Hardouin

et al. 2010

Journal of Bone and Mineral Research

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“…(38) As a consequence, Bmi-1 through inhibition of p16, p19, and p27 maintained self-renewal capacity of BM-MSCs and promoted their differentiation into osteoblasts, while inhibiting their differentiation into adipocytes. In previous studies, we found that the expression of Bmi-1 in Pthrp KI mouse bone tissue was significantly reduced and its nuclear translocation was significantly reduced.…”

Section: Discussionmentioning

confidence: 94%

The p27 Pathway Modulates the Regulation of Skeletal Growth and Osteoblastic Bone Formation by Parathyroid Hormone–Related Peptide

Zhu

Zhang

Zhan

et al. 2015

Journal of Bone and Mineral Research

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Parathyroid hormone-related peptide (PTHrP) 1-84 knock-in mice (Pthrp KI) develop skeletal growth retardation and defective osteoblastic bone formation. To further examine the mechanisms underlying this phenotype, microarray analyses of differential gene expression profiles were performed in long bone extracts from Pthrp KI mice and their wild-type (WT) littermates. We found that the expression levels of p27, p16, and p53 were significantly upregulated in Pthrp KI mice relative to WT littermates. To determine whether p27 was involved in the regulation by PTHrP of skeletal growth and development in vivo, we generated compound mutant mice, which were homozygous for both p27 deletion and the Pthrp KI mutation (p27 -/-Pthrp KI). We then compared p27 -/-Pthrp KI mice with p27 -/-, Pthrp KI, and WT littermates. Deletion of p27 in Pthrp KI mice resulted in a longer lifespan, increased body weight, and improvement in skeletal growth. At 2 weeks of age, skeletal parameters, including length of long bones, size of epiphyses, numbers of proliferating cell nuclear antigen (PCNA)-positive chondrocytes, bone mineral density, trabecular bone volume, osteoblast numbers, and alkaline phosphatase (ALP)-, type I collagen-, and osteocalcin-positive bone areas were increased in p27 -/-mice and reduced in both Pthrp KI and p27 -/-Pthrp KI mice compared with WT mice; however, these parameters were increased in p27 -/-Pthrp KI mice compared with Pthrp KI mice. As well, protein expression levels of PTHR, IGF-1, and Bmi-1, and the numbers of total colony-forming unit fibroblastic (CFU-f) and ALP-positive CFU-f were similarly increased in p27 -/-Pthrp KI mice compared with Pthrp KI mice. Our results demonstrate that deletion of p27 in Pthrp KI mice can partially rescue defects in skeletal growth and osteoblastic bone formation by enhancing endochondral bone formation and osteogenesis. These studies, therefore, indicate that the p27 pathway may function downstream in the action of PTHrP to regulate skeletal growth and development.

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“…Calcein double-labeling was performed by i.p. injection of calcein (10 mg/g body weight; C-0875; Sigma-Aldrich) at 6 and 1 days prior to sacrifice, as described previously (59). Bones were harvested and embedded in LR White acrylic resin.…”

Section: Methodsmentioning

confidence: 99%

NOTCH inhibits osteoblast formation in inflammatory arthritis via noncanonical NF-κB

Zhang¹,

Hilton²,

Anolik³

et al. 2014

J. Clin. Invest.

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NOTCH-dependent signaling pathways are critical for normal bone remodeling; however, it is unclear if dysfunctional NOTCH activation contributes to inflammation-mediated bone loss, as observed in rheumatoid arthritis (RA) patients. We performed RNA sequencing and pathway analyses in mesenchymal stem cells (MSCs) isolated from transgenic TNF-expressing mice, a model of RA, to identify pathways responsible for decreased osteoblast differentiation. 53 pathways were dysregulated in MSCs from RA mice, among which expression of genes encoding NOTCH pathway members and members of the noncanonical NF-κB pathway were markedly elevated. Administration of NOTCH inhibitors to RA mice prevented bone loss and osteoblast inhibition, and CFU-fibroblasts from RA mice treated with NOTCH inhibitors formed more new bone in recipient mice with tibial defects. Overexpression of the noncanonical NF-κB subunit p52 and RELB in a murine pluripotent stem cell line increased NOTCH intracellular domain-dependent (NICD-dependent) activation of an RBPjκ reporter and levels of the transcription factor HES1. TNF promoted p52/RELB binding to NICD, which enhanced binding at the RBPjκ site within the Hes1 promoter. Furthermore, MSC-enriched cells from RA patients exhibited elevated levels of HES1, p52, and RELB. Together, these data indicate that persistent NOTCH activation in MSCs contributes to decreased osteoblast differentiation associated with RA and suggest that NOTCH inhibitors could prevent inflammation-mediated bone loss. IntroductionPatients with chronic inflammatory diseases, such as rheumatoid arthritis (RA), often have severe systemic bone loss and increased risk of fracture due to increased bone resorption and decreased bone formation, partially mediated by elevated TNF levels (1). We (1-4) and others (5, 6) have reported that TNF inhibits bone formation by affecting major osteoblast regulatory pathways, including BMP/SMAD/RUNX2 and WNT-β-catenin, but the role of TNF in osteoblast differentiation from MSCs has not been fully defined. The TNF transgenic (TNF-Tg) mouse model we use, line 3647, represents a good model of RA to study the influence of chronically elevated, but relatively low, levels of TNF and TNF-induced inflammation on bone cell function and MSC differentiation into osteoblasts (7). To attempt to identify molecules responsible for reduced differentiation of MSCs into osteoblasts in RA, we performed genome-wide screening and pathway analyses using data from RNA sequencing (RNA-Seq) of MSCs purified from TNF-Tg mice and WT littermates. We found that genes in the NOTCH and noncanonical NF-κB signaling pathways were markedly upregulated in TNF-Tg mouse MSCs, raising the possibility that NOTCH may interact with noncanonical NF-κB proteins in MSCs to inhibit their osteogenic differentiation.NOTCH is a family of evolutionarily conserved receptors that regulate cell fate. NOTCH receptors are activated following direct contact with their ligands expressed on adjacent cells. In mammals, there are 4 NOTCH receptors (NOTCH1-NOTCH4)...

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Defects in mesenchymal stem cell self-renewal and cell fate determination lead to an osteopenic phenotype in Bmi-1 null mice

Cited by 86 publications

References 51 publications

TNF-α's effects on proliferation and apoptosis in human mesenchymal stem cells depend on RUNX2 expression

TNF-α's effects on proliferation and apoptosis in human mesenchymal stem cells depend on RUNX2 expression

The p27 Pathway Modulates the Regulation of Skeletal Growth and Osteoblastic Bone Formation by Parathyroid Hormone–Related Peptide

NOTCH inhibits osteoblast formation in inflammatory arthritis via noncanonical NF-κB

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