Overexpressed IGFBP5 promotes cell proliferation and inhibits apoptosis of nucleus pulposus derived from rats with disc degeneration through inactivating the ERK/MAPK axis

Deletion of endothelial IGFBP5 protects against ischaemic hindlimb injury by promoting angiogenesis

BACKGROUND

Angiogenesis is critical for forming new blood vessels from antedating vascular vessels. The endothelium is essential for angiogenesis, vascular remodelling and minimisation of functional deficits following ischaemia. The insulin-like growth factor (IGF) family is crucial for angiogenesis. Insulin-like growth factor-binding protein 5 (IGFBP5), a binding protein of the IGF family, may have places in angiogenesis, but the mechanisms are not yet completely understood. We sought to probe whether IGFBP5 is involved in pathological angiogenesis and uncover the molecular mechanisms behind it.

METHODS AND RESULTS

IGFBP5 expression was elevated in the vascular endothelium of gastrocnemius muscle from critical limb ischaemia patients and hindlimb ischaemic (HLI) mice and hypoxic human umbilical vein endothelial cells (HUVECs). In vivo, loss of endothelial IGFBP5 (IGFBP5EKO) facilitated the recovery of blood vessel function and limb necrosis in HLI mice. Moreover, skin damage healing and aortic ring sprouting were faster in IGFBP5EKO mice than in control mice. In vitro, the genetic inhibition of IGFBP5 in HUVECs significantly promoted tube formation, cell proliferation and migration by mediating the phosphorylation of IGF1R, Erk1/2 and Akt. Intriguingly, pharmacological treatment of HUVECs with recombinant human IGFBP5 ensued a contrasting effect on angiogenesis by inhibiting the IGF1 or IGF2 function. Genetic inhibition of IGFBP5 promoted cellular oxygen consumption and extracellular acidification rates via IGF1R-mediated glycolytic adenosine triphosphate (ATP) metabolism. Mechanistically, IGFBP5 exerted its role via E3 ubiquitin ligase Von Hippel-Lindau (VHL)-regulated HIF1α stability. Furthermore, the knockdown of the endothelial IGF1R partially abolished the reformative effect of IGFBP5EKO mice post-HLI.

CONCLUSION

Our findings demonstrate that IGFBP5 ablation enhances angiogenesis by promoting ATP metabolism and stabilising HIF1α, implying IGFBP5 is a novel therapeutic target for treating abnormal angiogenesis-related conditions.

SFRP4+IGFBP5hi NKT cells induced neural-like cell differentiation to contribute to adenomyosis pain

Background

Adenomyosis is an estrogen-dependent gynecological disease. The pathogenesis of chronic pain, the main clinical symptom of adenomyosis, remains undefined. As a combination lymphocyte with both T-cell and natural killer (NK)-cell properties, NK T (NKT) cells play a role in immune defense against numerous diseases and modulate cell differentiation.

Method

This study analyzed the tissue-cell samples from adenomyosis with or without pain by single-cell sequencing.

Result

We found a specific population of secreted frizzled-related protein 4 (SFRP4)⁺NKT cells and a large amount of undifferentiated multipotent stem cells in the adenomyosis pain group. We discovered that a high expression of IGFBP5 in SFRP4⁺NKT cells could promote the differentiation of multipotent stem cells into neural-like cells via the single-cell trajectory. Through verification by the sample, we found that the degree of the expression of the neuronal marker NEFM was correlated with the duration of pain in adenomyosis patients. The expression of IGFBP5 was positively correlated with the pain scores of adenomyosis patients.

Conclusion

Collectively, these findings suggest that SFRP4⁺IGFBP5^hi NKT cells were capable of converting part of the stem cells into neurogenic cells and inducing adenomyosis pain.

MiR-1260b protects against LPS-induced degenerative changes in nucleus pulposus cells through targeting TCF7L2

Nucleus pulposus (NP) cells play a critical role in maintaining intervertebral disc integrity through producing the components of extracellular matrix (ECM). NP cell dysfunction, including senescence and hyper-apoptosis, has been regarded as critical events during intervertebral disc degeneration development. In the present study, we found that Transcription Factor 7-Like 2 (TCF7L2) was overexpressed within degenerative intervertebral disc tissue samples, and TCF7L2 silencing improved lipopolysaccharide (LPS)-induced repression on NP cell proliferation, ECM synthesis, and LPS-induced NP cell senescence. miR-1260b directly targeted TCF7L2 and inhibited TCF7L2 expression. miR-1260b overexpression improved LPS-induced degenerative changes in NP cells; more importantly, TCF7L2 overexpression significantly reversed the effects of miR-1260b overexpression on LPS-stimulated degenerative changes within NP cells. For the first time, we demonstrated the function of the miR-1260b/TCF7L2 axis on the phenotypic maintenance of chondrocyte-like NP cells and ECM synthesis by NP cells under LPS stimulation.

Identification of key genes in benign prostatic hyperplasia using bioinformatics analysis

PURPOSE

This study aimed to identify differentially expressed genes (DEGs) and pathways in benign prostatic hyperplasia (BPH) by comprehensive bioinformatics analysis.

METHODS

Data of the gene expression microarray (GSE6099) were downloaded from GEO database. DEGs were obtained by GEO2R. Functional and enrichment analyses of selected genes were performed using DAVID database. Protein-protein interaction network was constructed through STRING. Anterior gradient 2 (ARG2) and lumican (LUM) staining in paraffin-embedded specimens from BPH and normal prostate (NP) were detected by immunohistochemistry (IHC). Differences between groups were analyzed by the Student's t test.

RESULTS

A total of 24 epithelial DEGs and 39 stromal DEGs were determined. The GO analysis results showed that epithelial DEGs between BPH and NP were enriched in biological processes of glucose metabolic process, glucose homeostasis and negative regulation of Rho protein signal transduction. For DEGs in stroma, enriched biological processes included response to ischemia, antigen processing and presentation, cartilage development, T cell costimulation and energy reserve metabolic process. ARG2, as one of the epithelial DEGs, was mainly located in epithelial cells of prostate. In addition, LUM is primarily expressed in the stroma. We further confirmed that compared with NP, the BPH have the lower ARG2 protein level (p = 0.029) and higher LUM protein level (p = 0.003) using IHC.

CONCLUSIONS

Our study indicated that there are possible differentially expressed genes in epithelial and stromal cells, such as ARG2 and LUM, which may provide a novel insight for the pathogenesis of BPH.

Gene expression profile of lipopolysaccharide‑induced apoptosis of nucleus pulposus cells reversed by syringic acid

Apoptosis of nucleus pulposus (NP) cells has an important role in the process of intervertebral disc degeneration (IDD), and the search for novel compounds to prevent apoptosis from occurring is urgently required. In the present study, syringic acid (SyrA) was found to exhibit no cytotoxicity on NP cells, and was able to reverse the cytotoxicity, as well as the abnormal expression of Bcl-2 and caspase-3, that were induced by lipopolysaccharide (LPS). The transcriptomes of each group were then analyzed using RNA-Seq. A total of 65 differentially expressed genes (DEGs) were identified in LPS-stimulated groups (LPS group vs. control group), 819 DEGs were identified in the SyrA-reversed groups (SyrA plus LPS group vs. LPS group), and a further 25 DEGs were identified in the SyrA plus LPS group compared with the control group. Reverse transcription-quantitative PCR validation indicated that the alterations in expression of uroplakin 3B-like 1 (UPK3BL1), voltage-dependent calcium channel subunit α-2/δ-1 (CACNA2D1) and polo-like kinase 4 (PLK4) were consistent with the corresponding results of RNA-Seq, and that these genes were involved in both LPS-stimulation and SyrA-reversion processes. Kyoto Encyclopedia of Genes and Genomes analyses indicated that the DEGs in SyrA-reversed groups were involved in, amongst other pathways, ‘Autophagy-other’ and ‘Apoptosis-multiple species’. In conclusion, the addition of SyrA to the NP cells co-incubated with LPS appeared to help prevent the abnormal expression of mRNAs and apoptosis that had been identified in NP cells incubated with LPS alone. The potential mechanism underlying the reversion of SyrA might be attributed to the regulation of CACNA2D1 and PLK4.

Engineered scaffolds based on mesenchymal stem cells/preosteoclasts extracellular matrix promote bone regeneration

Recently, extracellular matrix-based tissue-engineered bone is a promising approach to repairing bone defects, and the seed cells are mostly mesenchymal stem cells. However, bone remodelling is a complex biological process, in which osteoclasts perform bone resorption and osteoblasts dominate bone formation. The interaction and coupling of these two kinds of cells is the key to bone repair. Therefore, the extracellular matrix secreted by the mesenchymal stem cells alone cannot mimic a complex bone regeneration microenvironment, and the addition of extracellular matrix by preosteoclasts may contribute as an effective strategy for bone regeneration. Here, we established the mesenchymal stem cell/preosteoclast extracellular matrix -based tissue-engineered bones and demonstrated that engineered-scaffolds based on mesenchymal stem cell/ preosteoclast extracellular matrix significantly enhanced osteogenesis in a 3 mm rat femur defect model compared with mesenchymal stem cell alone. The bioactive proteins released from the mesenchymal stem cell/ preosteoclast extracellular matrix based tissue-engineered bones also promoted the migration, adhesion, and osteogenic differentiation of mesenchymal stem cells in vitro. As for the mechanisms, the iTRAQ-labeled mass spectrometry was performed, and 608 differentially expressed proteins were found, including the IGFBP5 and CXCL12. Through in vitro studies, we proved that CXCL12 and IGFBP5 proteins, mainly released from the preosteoclasts, contributed to mesenchymal stem cells migration and osteogenic differentiation, respectively. Overall, our research, for the first time, introduce pre-osteoclast into the tissue engineering of bone and optimize the strategy of constructing extracellular matrix-based tissue-engineered bone using different cells to simulate the natural bone regeneration environment, which provides new sight for bone tissue engineering.

Exercise protects proliferative muscle satellite cells against exhaustion via the Igfbp7-Akt-mTOR axis

Background and Purpose: The exhaustion of muscle satellite cells (SCs) is correlated with muscle diseases, including sarcopenia and Duchenne muscular dystrophy. Exercise benefits skeletal muscle homeostasis and promotes proliferation of SCs. Elucidating the molecular mechanism underlying the muscle function-improving effect of exercise has important implications in regenerative medicine.

Methods: Herein, we investigated the effect of 4-week treadmill training on skeletal muscle and SCs in mice. Hematoxylin and eosin (HE) staining was utilized to detect the morphometry of skeletal muscles. Flow cytometry and immunofluorescence were conducted to analyze the abundance and cell cycle of SCs. RNA sequencing was performed to elucidate the transcriptional regulatory network of SCs. The ChIP-PCR assay was used to detect enrichment of H3K27ac at the promoters of Akt.

Results: We observed that exercise resulted in muscle hypertrophy and improved muscle regeneration in mice. Unexpectedly, exercise promoted cell cycling but suppressed the Akt-mTOR pathway in SCs. Proliferative SCs in “exercised mice” required suppressed mTOR activity to limit mitochondrial metabolism, maintaining the “limited activation status” of SCs against exhaustion. Mechanistically, exercise upregulated the expression of Igfbp7, thereby impeding the phosphorylation of Akt and resulting in inhibited mTOR activity and limited mitochondrial metabolism. The limited mitochondrial metabolism resulted in hypoacetylation of histone 3 and reduced enrichment of H3K27ac at promoters of Akt, decreasing the transcription of Akt. Moreover, repeatedly injured mice showed a preserved SC pool and improved muscle regeneration by the suppression of Akt-mTOR signaling.

Conclusions: The findings of our study show that exercise protects proliferative SCs against exhaustion via the Igfbp7-Akt-mTOR axis. These findings establish a link between mechanical signaling, mitochondrial metabolism, epigenetic modification, and stem cell fate decisions; thus, present potential therapeutic targets for muscle diseases correlated with SC exhaustion.