isolation-cultivation-mandibular-bone-marrow-mesenchymal-stem-cells

Isolation and Cultivation of Mandibular Bone Marrow Mesenchymal Stem Cells in Rats

Here we present an efficient method for isolating and culturing mandibular bone marrow mesenchymal stem cells (mBMSCs) in vitro to rapidly obtain numerous ...

using-inducible-osteoblastic-lineage-specific-stat3-knockout-mice-to

Using Inducible Osteoblastic Lineage-Specific <em>Stat3</em> Knockout Mice to Study Alveolar Bone Remodeling During Orthodontic Tooth Movement

The alveolar bone, with a high turnover rate, is the most actively-remodeling bone in the body. Orthodontic tooth movement (OTM) is a common artificial ...

National Clinical Research Center of Stomatology

Shanghai Jiao Tong University School of Medicine

Shanghai Jiao Tong University

National Center for Stomatology

National Clinical Research Center for Oral Diseases

Shanghai Key Laboratory of Stomatology

The transcription factor signal transducer and activator of transcription 3 (STAT3) plays a central role in cell survival and function. STAT3 has been demonstrated to participate in the maintenance of bone homeostasis in osteoblasts, but its role in osteoclasts  remains poorly defined. Here, we generated a conditional knockout mouse model in which  was deleted in osteoclasts using a cathepsin K-Cre (Ctsk-Cre) driver. We observed that osteoclast-specific  deficiency caused increased bone mass in mice, which we attributed to impaired bone catabolism by osteoclasts. -deficient bone marrow macrophages (BMMs) showed decreased expression of nuclear factor of activated T cells, cytoplasm 1 (NFATc1), and reduced osteoclast differentiation determined by decreases in osteoclast number, tartrate-resistant acid phosphatase activity, and expression of osteoclast marker genes. Enforced expression of NFATc1 in -deficient BMMs rescued the impaired osteoclast differentiation. Mechanistically, we revealed that STAT3 could drive the transcription of NFATc1 by binding to its promoter. Furthermore, preventing STAT3 activation by using an inhibitor of upstream phosphorylases, AG490, also impaired osteoclast differentiation and formation in a similar way as gene deletion of  In summary, our data provide the first evidence that STAT3 is significant in osteoclast differentiation and bone homeostasis , and it may be identified as a potential pharmacological target for the treatment of bone metabolic diseases through regulation of osteoclast activity.

STAT3 controls osteoclast differentiation and bone homeostasis by regulating NFATc1 transcription.

Alveolar bone osteoporosis has attracted more and more attention because of its profound impact on stomatognathic function and treatment, but current treatments have not been targeted to alveolar bone and might even cause severe side effects. Thus, identifying the effects of anti-osteoporosis agents on alveolar bone is essential. Icariin ameliorates metabolic dysfunction of long bones, but its effects on alveolar bone remain unclarified.

Icariin prevents oestrogen deficiency-induced alveolar bone loss through promoting osteogenesis via STAT3.

Based on the Cre-Loxp gene knockout system, this study intended to construct tamoxifen-inducible STAT3 conditional knockout mice and verify the knockout efficiency.

[Generation and validation of inducible osteoblast-specific Stat3 knockout mice].

The novel small molecule Napabucasin (also known as BBI608) was shown to inhibit gene transcription driven by Signal Transducer and Activator of Transcription 3 (STAT3), which is considered a promising anticancer target. Many preclinical studies have been conducted in cancer patients examining the selective targeting of cancer stem cells by Napabucasin, but few studies have examined side effects of Napabucasin in the skeleton system. In the present study, we found treating bone marrow mesenchymal stem cells (BMSCs) with Napabucasin  impaired their osteogenic differentiation. In terms of mechanisms, Napabucasin disrupted differentiation of BMSCs by inhibiting the transcription of osteogenic gene osteocalcin (Ocn) through STAT3. Moreover, through micro-CT analysis we found 4 weeks of Napabucasin injections induced mouse bone loss. Histological analysis revealed that Napabucasin-induced bone loss in mice was the result of impaired osteogenesis. In conclusion, this study provided evidence for the effect of Napabucasin on mouse bone homeostasis and revealed its underlying mechanisms  and .

Napabucasin Induces Mouse Bone Loss by Impairing Bone Formation via STAT3.

Skeletal deformities are typical AD-HIES manifestations, which are mainly caused by heterozygous and loss-of-function mutations in Signal transducer and activator of transcription 3 (STAT3). However, the mechanism is still unclear and the treatment strategy is limited. Herein, we reported that the mice with Stat3 deletion in osteoblasts, but not in osteoclasts, induced AD-HIES-like skeletal defects, including craniofacial malformation, osteoporosis, and spontaneous bone fracture. Mechanistic analyses revealed that STAT3 in cooperation with Msh homeobox 1(MSX1) drove osteoblast differentiation by promoting Distal-less homeobox 5(Dlx5) transcription. Furthermore, pharmacological activation of STAT3 partially rescued skeletal deformities in heterozygous knockout mice, while inhibition of STAT3 aggravated bone loss. Taken together, these data show that STAT3 is critical for modulating skeletal development and maintaining bone homeostasis through STAT3-indcued osteogenesis and suggest it may be a potential target for treatments.

STAT3 is critical for skeletal development and bone homeostasis by regulating osteogenesis.

Mechanical force is essential to shape the internal architecture and external form of the skeleton by regulating the bone remodeling process. However, the underlying mechanism of how the bone responds to mechanical force remains elusive. Here, we generated both orthodontic tooth movement (OTM) model in vivo and a cyclic stretch-loading model in vitro to investigate biomechanical regulation of the alveolar bone. In this study, signal transducer and activator of transcription 3 (STAT3) was screened as one of the mechanosensitive proteins by protein array analysis of cyclic stretch-loaded bone mesenchymal stem cells (BMSCs) and was also proven to be activated in osteoblasts in response to the mechanical force during OTM. With an inducible osteoblast linage-specific Stat3 knockout model, we found that Stat3 deletion decelerated the OTM rate and reduced orthodontic force-induced bone remodeling, as indicated by both decreased bone resorption and formation. Both genetic deletion and pharmacological inhibition of STAT3 in BMSCs directly inhibited mechanical force-induced osteoblast differentiation and impaired osteoclast formation via osteoblast-osteoclast cross-talk under mechanical force loading. According to RNA-seq analysis of Stat3-deleted BMSCs under mechanical force, matrix metalloproteinase 3 (Mmp3) was screened and predicted to be a downstream target of STAT3. The luciferase and ChIP assays identified that Stat3 could bind to the Mmp3 promotor and upregulate its transcription activity. Furthermore, STAT3-inhibitor decelerated tooth movement through inhibition of the bone resorption activity, as well as MMP3 expression. In summary, our study identified the mechanosensitive characteristics of STAT3 in osteoblasts and highlighted its critical role in force-induced bone remodeling during orthodontic tooth movement via osteoblast-osteoclast cross-talk. © 2022 American Society for Bone and Mineral Research (ASBMR).

Osteoblastic STAT3 Is Crucial for Orthodontic Force Driving Alveolar Bone Remodeling and Tooth Movement.

Bone exhibits changes in density, strength, and microarchitecture in relation to mechanical loading mediated by exercise. Appropriate exercise maintains bone homeostasis, while the absence of exercise leads to disuse bone loss. However, the acting mechanism of mechanotransduction in bone remains unclear. We performed the running-wheel exercise and tail suspension model to study the effects of exercise on bone metabolism, and found that osteoblastic Signal transducer and activator of transcription 3 (STAT3) activity was closely related to exercise-induced bone mass and metabolism changes. With the Flexcell tension-loading system , mechanical force promoted STAT3 activity, which was accompanied by increased osteoblastic differentiation of the bone marrow mesenchymal stem cells (BMSCs). In contrast, the inhibition of STAT3 phosphorylation blocked force-induced osteoblastic differentiation. Furthermore, pharmacological inactivation of STAT3 impaired the increase in exercise-induced bone mass and osteogenesis. With an inducible conditional deletion mouse model, we found that the osteoblast lineage-specific Stat3 deletion could also block force-induced osteoblastic differentiation  and impair exercise-promoted bone mass and osteogenesis . This confirmed the crucial role of osteoblastic STAT3 in exercise-mediated bone metabolism. Finally, colivelin, a STAT3 agonist, promoted osteoblastic differentiation  and partly rescued exercise loss-induced disuse bone loss by improving osteogenesis in the tail suspension model. Taken together, our study revealed the essential role of STAT3 in maintaining exercise-mediated bone homeostasis. In addition, STAT3 might act as a potential target for osteoporosis caused by exercise loss.

Exercise maintains bone homeostasis by promoting osteogenesis through STAT3.

Periodontal ligament (PDL) and dental pulp (DP) share a common origin but have distinct biological and mechanical functions. To what extent the mechanoresponsive property of PDL can be attributed to its unique transcriptional profiles of cellular heterogeneity is unclear. This study aims to decipher cellular heterogeneity and distinct mechanoresponsive characteristics of odontogenic soft tissues and their underlying molecular mechanisms.

ArticleTotal : 2	Year
Publication title	2020
Publication title	2023

Article	Year
STAT3 controls osteoclast differentiation and bone homeostasis by regulating NFATc1 transcription. The Journal of biological chemistry\| PubMed ID: 31462535	2019
Icariin prevents oestrogen deficiency-induced alveolar bone loss through promoting osteogenesis via STAT3. Cell proliferation\| PubMed ID: 31943455	2020
[Generation and validation of inducible osteoblast-specific Stat3 knockout mice]. Shanghai kou qiang yi xue = Shanghai journal of stomatology\| PubMed ID: 33089278	2020
Napabucasin Induces Mouse Bone Loss by Impairing Bone Formation via STAT3. Frontiers in cell and developmental biology\| PubMed ID: 33816498	2021
STAT3 is critical for skeletal development and bone homeostasis by regulating osteogenesis. Nature communications\| PubMed ID: 34824272	2021
Osteoblastic STAT3 Is Crucial for Orthodontic Force Driving Alveolar Bone Remodeling and Tooth Movement. Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research\| PubMed ID: 36370067	2023
Exercise maintains bone homeostasis by promoting osteogenesis through STAT3. International journal of biological sciences\| PubMed ID: 37151888	2023
ScRNA-seq links dental fibroblasts heterogeneity with mechanoresponsiveness. Journal of periodontal research\| PubMed ID: 37221903	2023

Xiangru Huang

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