Ghrelin promotes the osteogenic differentiation of rMSCs via miR-206 and the ERK1/2 pathway

LNX2 involves in the role of ghrelin to promote the neuronal differentiation of adipose tissue-derived mesenchymal stem cells

Adipose tissue-derived mesenchymal stem cells (ADSCs) have promising effects on nerve repair due to the differentiation ability to neural cells. Ghrelin has been shown to promote the neural differentiation of ADSCs. This work was designed to explore its underlying mechanism. Herein, we found high expression of LNX2 in ADSCs after neuronal differentiation. Knockdown of LNX2 might block neuronal differentiation of ADSCs, as evidenced by the decreased number of neural-like cells and dendrites per cell, and the reduced expressions of neural markers (including β-Tubulin III, Nestin, and MAP2). We also demonstrated that LNX2 silencing suppressed the nuclear translocation of β-catenin in differentiated ADSCs. Luciferase reporter assay indicated that LNX2 inhibited wnt/β-catenin pathway by reducing its transcriptional activity. In addition, results showed that LNX2 expression was increased by ghrelin, and its inhibition diminished the effects of ghrelin on neuronal differentiation. Altogether, the results suggest that LNX2 is involved in the role of ghrelin to facilitate neuronal differentiation of ADSCs.

Morphological feature recognition of different differentiation stages of induced ADSCs based on deep learning

In order to accurately identify the morphological features of different differentiation stages of induced Adipose Derived Stem Cells (ADSCs) and judge the differentiation types of induced ADSCs, a morphological feature recognition method of different differentiation stages of induced ADSCs based on deep learning is proposed. Using the super-resolution image acquisition method of ADSCs differentiation based on stimulated emission depletion imaging, after obtaining the super-resolution images at different stages of inducing ADSCs differentiation, the noise of the obtained image is removed and the image quality is optimized through the ADSCs differentiation image denoising model based on low rank nonlocal sparse representation; The denoised image is taken as the recognition target of the morphological feature recognition method for ADSCs differentiation image based on the improved Visual Geometry Group (VGG-19) convolutional neural network. Through the improved VGG-19 convolutional neural network and class activation mapping method, the morphological feature recognition and visual display of the recognition results at different stages of inducing ADSCs differentiation are realized. After testing, this method can accurately identify the morphological features of different differentiation stages of induced ADSCs, and is available.

Circadian clock genes as promising therapeutic targets for bone loss

The circadian clock regulates many key physiological processes such as the sleep-wake cycle, hormone release, cardiovascular health, glucose metabolism and body temperature. Recent evidence has suggested a critical role of the circadian system in controlling bone metabolism. Here we review the connection between bone metabolism and the biological clock, and the roles of these mechanisms in bone loss. We also analyze the regulatory effects of clock-related genes on signaling pathways and transcription factors in osteoblasts and osteoclasts. Additionally, osteocytes and endothelial cells (ECs) regulated by the circadian clock are also discussed in our review. Furthermore, we also summarize the regulation of circadian clock genes by some novel modulators, which provides us with a new insight into a potential strategy to prevent and treat bone diseases such as osteoporosis by targeting circadian genes.

LIM Mineralization Protein-1 Enhances the Committed Differentiation of Dental Pulp Stem Cells through the ERK1/2 and p38 MAPK Pathways and BMP Signaling

Tissue regeneration is the preferred treatment for dentin and bone tissue defects. Dental pulp stem cells (DPSCs) have been extensively studied for their use in tissue regeneration, including the regeneration of dentin and bone tissue. LIM mineralization protein-1 (LMP-1) is an intracellular non-secretory protein that plays a positive regulatory role in the mineralization process. In this study, an LMP-1-induced DPSCs model was used to explore the effect of LMP-1 on the proliferation and odonto/osteogenic differentiation of DPSCs, as well as the underlying mechanisms. As indicated by the cell counting kit-8 assay, the results showed that LMP-1 did not affect the proliferation of DPSCs. Overexpression of LMP-1 significantly promoted the committed differentiation of DPSCs and vice versa, as shown by alkaline phosphatase activity assay, alizarin red staining, western blot assay, quantitative real-time polymerase chain reaction assay, and in vivo mineralized tissue formation assay. Furthermore, inhibiting the activation of the extracellular signal-regulated kinase 1/2 (ERK1/2), p38 mitogen-activated protein kinase (MAPK), and c-Jun N-terminal kinase (JNK) pathways using specific pathway inhibitors showed that the ERK1/2 and p38 MAPK pathways attenuated the differentiation of DPSCs. Besides, the expression of BMP signaling pathway components were also determined, which suggested that LMP-1 could activate BMP-2/Smad1/5 signaling pathway. Our results not only indicated the underlying mechanism of LMP-1 treated DPSCs but also provided valuable insight into therapeutic strategies in regenerative medicine.

MYOD1 inhibits avian adipocyte differentiation via miRNA-206/KLF4 axis

BACKGROUND

A considerable number of muscle development-related genes were differentially expressed in the early stage of avian adipocyte differentiation. However, the functions of them in adipocyte differentiation remain largely known. In this study, the myoblast determination protein 1 (MYOD1) was selected as a representative of muscle development. We investigated its expression, function, and regulation in avian adipocyte differentiation.

RESULTS

The expression of MYOD1 decreased significantly in the early stage of avian adipocyte differentiation. CRISPR/Cas9-mediated deletion of MYOD1 induced adipocyte differentiation, whereas over-expression of MYOD1 inhibited adipogenesis. The mRNA-seq data showed that MYOD1 could perturb the lipid biosynthetic process during differentiation. Our results showed that MYOD1 directly up-regulates the miR-206 expression by binding the upstream 1200 bp region of miR-206. Then, over-expression of miR-206 can inhibit the adipogenesis. Furthermore, MYOD1 affected the expression of endogenous miR-206 and its target gene Kruppel-like factor 4 (KLF4), which is an important activator of adipogenesis. Accordingly, the inhibition of miR-206 or over-expression of KLF4 could counteract the inhibitory effect of MYOD1 on adipocyte differentiation.

CONCLUSIONS

Our results establish that MYOD1 inhibits adipocyte differentiation by up-regulating miR-206 to suppress the KLF4 expression. These findings identify a novel function of MYOD1 in adipocyte differentiation, suggesting a potential role in body-fat distribution regulation.

Curcumin reduces apoptosis and promotes osteogenesis of human periodontal ligament stem cells under oxidative stress in vitro and in vivo

AIMS

Human periodontal ligament stem cells (hPDLSCs) tether the teeth to the surrounding bone and are considered as major functional stem cells responsible for regeneration of the alveolar bone and periodontal ligament tissue. However, the outcome of stem cell regenerative therapy is affected by the survival rate and their differentiation potential of transplanted cells. This is primarily because of local oxidative stress and chronic inflammation at the transplantation site. Therefore, our study aimed to explore whether a natural antioxidant, curcumin could increase the tissue regeneration ability of transplanted hPDLSCs.

MAIN METHODS

A hydrogen peroxide environment and a rat cranial bone defect model were built to mimic the oxidative stress conditions in vitro and in vivo, respectively. We evaluated the effect of curcumin on oxidative status, apoptosis, mitochondrial function and osteogenic differentiation of H2O2-stimulated hPDLSCs in vitro. We also measured the effect of curcumin on cell viability and bone repair ability of transplanted hPDLSCs in vivo.

KEY FINDINGS

Our data showed that curcumin enhanced cell proliferation, reduced the reactive oxygen species (ROS) levels and apoptosis, maintained the standard mitochondrial structure and function, and promoted osteogenic differentiation of H2O2-stimulated hPDLSCs. The extracellular regulated protein kinases 1/2 (Erk1/2) signaling pathway was determined to be involved in the osteogenic differentiation of the H2O2-stimulated hPDLSCs. Moreover, curcumin enhanced the viability and the bone repair ability of hPDLSCs in vivo.

SIGNIFICANCE

Curcumin reduced apoptosis and promoted osteogenesis of the hPDLSCs under oxidative stress, and might therefore have a potential clinical use with respect to tissue regeneration.