The effects of Hedgehog on the RNA-binding protein Msi1 in the proliferation and apoptosis of mesenchymal stem cells

Baicalin attenuates dexamethasone-induced apoptosis of bone marrow mesenchymal stem cells by activating the hedgehog signaling pathway

BACKGROUND

Perturbations in bone marrow mesenchymal stem cell (BMSC) differentiation play an important role in steroid-induced osteonecrosis of the femoral head (SONFH). At present, studies on SONFH concentrate upon the balance within BMSC osteogenic and adipogenic differentiation. However, BMSC apoptosis as well as proliferation are important prerequisites in their differentiation. The hedgehog (HH) signaling pathway regulates bone cell apoptosis. Baicalin (BA), a well-known compound in traditional Chinese medicine, can affect the proliferation and apoptosis of numerous cell types via HH signaling. However, the potential role and mechanisms of BA on BMSCs are unclear. Thus, we aimed to explore the role of BA in dexamethasone (Dex)-induced BMSC apoptosis in this study.

METHODS

Primary BMSCs were treated with 10 -6 mol/L Dex alone or with 5.0 μmol/L, 10.0 μmol/L, or 50.0 μmol/L BA for 24 hours followed by co-treatment with 5.0 μmol/L, 10.0 μmol/L, or 50.0 μmol/L BA and 10 -6 mol/L Dex. Cell viability was assayed through the Cell Counting Kit-8 (CCK-8). Cell apoptosis was evaluated using Annexin V-fluorescein isothiocyanate/propidium iodide (PI) staining followed by flow cytometry. The imaging and counting, respectively, of Hochest 33342/PI-stained cells were used to assess the morphological characteristics and proportion of apoptotic cells. To quantify the apoptosis-related proteins (e.g., apoptosis regulator BAX [Bax], B-cell lymphoma 2 [Bcl-2], caspase-3, and cleaved caspase-3) and HH signaling pathway proteins, western blotting was used. A HH-signaling pathway inhibitor was used to demonstrate that BA exerts its anti-apoptotic effects via the HH signaling pathway.

RESULTS

The results of CCK-8, Hoechst 33342/PI-staining, and flow cytometry showed that BA did not significantly promote cell proliferation (CCK-8: 0 μmol/L, 100%; 2.5 μmol/L, 98.58%; 5.0 μmol/L, 95.18%; 10.0 μmol/L, 98.11%; 50.0 μmol/L, 99.38%, F   =  2.33, P   >  0.05), but it did attenuate the effect of Dex on apoptosis (Hoechst 33342/PI-staining: Dex+ 50.0 μmol/L BA, 12.27% vs. Dex, 39.27%, t  = 20.62; flow cytometry: Dex + 50.0 μmol/L BA, 12.68% vs. Dex, 37.43%, t  = 11.56; Both P  < 0.05). The results of western blotting analysis showed that BA reversed Dex-induced apoptosis by activating the HH signaling pathway, which down-regulated the expression of Bax, cleaved-caspase 3, and suppressor of fused (SUFU) while up-regulating Bcl-2, sonic hedgehog (SHH), and zinc finger protein GLI-1 (GLI-1) expression (Bax/Bcl-2: Dex+ 50.0 μmol/L BA, 1.09 vs. Dex, 2.76, t  = 35.12; cleaved caspase-3/caspase-3: Dex + 50.0 μmol/L BA, 0.38 vs . Dex, 0.73, t  = 10.62; SHH: Dex + 50.0 μmol/L BA, 0.50 vs . Dex, 0.12, t  = 34.01; SUFU: Dex+ 50.0 μmol/L BA, 0.75 vs . Dex, 1.19, t  = 10.78; GLI-1: Dex+ 50.0 μmol/L BA, 0.40 vs . Dex, 0.11, t  = 30.68. All P  < 0.05).

CONCLUSIONS

BA antagonizes Dex-induced apoptosis of human BMSCs by activating the HH signaling pathway. It is a potential candidate for preventing SONFH.

Msi1 inhibits cervical cancer cell apoptosis by downregulating BAK through AKT signaling

Musashi-1 (Msi1) is an RNA binding protein that functions as a regulator in multiple carcinomas. Our previous study demonstrated that Msi1 could promote the proliferation of cervical cancer cells by targeting the cell cycle proteins P21, P27 and P53. However, the mechanisms by which Msi1 affects the survival of cervical cancer cells, such as apoptosis, are still unclear. In this study, we found that the expression of Msi1 inhibited cervical cancer cell apoptosis in vitro and in vivo. Furthermore, the expression of Msi1 downregulated the expression of PTEN, while AKT signaling was activated, which resulted in a reduction in the proapoptotic protein BAK. In addition, rescue the expression of BAK in Msi1 expressing cervical cancer cells induced the increase of apoptosis cells. These findings indicate that Msi1 regulates cervical cancer cell apoptosis by inhibiting PTEN and activating AKT signaling, which leads to the downregulation of BAK.

Sonic Hedgehog, a Novel Endogenous Damage Signal, Activates Multiple Beneficial Functions of Human Endometrial Stem Cells

Local endometrial stem cells play an important role in regulating endometrial thickness, which is an essential factor for successful embryo implantation and pregnancy outcomes. Importantly, defects in endometrial stem cell function can be responsible for thin endometrium and subsequent recurrent pregnancy losses. Therefore, many researchers have directed their efforts toward finding a novel stimulatory factor that can enhance the regenerative capacity of endometrial stem cells. Sonic hedgehog (SHH) is a morphogen that plays a key role in regulating pattern formation throughout embryonic limb development. In addition to this canonical function, we identified for the first time that SHH is actively secreted as a stem cell-activating factor in response to tissue injury and subsequently stimulates tissue regeneration by promoting various beneficial functions of endometrial stem cells. Our results also showed that SHH exerts stimulatory effects on endometrial stem cells via the FAK/ERK1/2 and/or phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathways. More importantly, we also observed that endometrial stem cells stimulated with SHH showed markedly enhanced differentiation and migratory capacities and subsequent in vivo therapeutic effects in an endometrial ablation animal model.

Expression of Musashi-1 During Osteogenic Differentiation of Oral MSC: An In Vitro Study

Background: Musashi-1 (MSI1) is a negative regulator of mesenchymal stromal cell (MSC) differentiation which in turn favors cell proliferation. However, little is known about its expression by MSC from the oral cavity and in the context of osteogenic differentiation. Aim: The aim of this study was to analyze the expression of MSI1 in the context of osteogenic differentiation of MSC derived from the oral cavity. Material/methods: For this in vitro study, MSC were isolated from six different origins of the oral cavity. They were extensively characterized in terms of proliferative and clonogenicity potential, expression of stemness genes (MYC, NANOG, POU5F1, and SOX2), expression of surface markers (CD73, CD90, CD105, CD14, CD31, CD34, and CD45) and adipo-, chondro- and osteogenic differentiation potential. Then, osteogenic differentiation was induced and the expression of MSI1 mRNA and other relevant markers of osteogenic differentiation, including RUNX2 and Periostin, were also evaluated. Results: Cell populations from the alveolar bone (pristine or previously grafted with xenograft), dental follicle, dental germ, dental pulp, and periodontal ligament were obtained. The analysis of proliferative and clonogenicity potential, expression of the stemness genes, expression of surface markers, and differentiation potential showed similar characteristics to those of previously published MSC from the umbilical cord. Under osteogenic differentiation conditions, all MSC populations formed calcium deposits and expressed higher SPARC. Over time, the expression of MSI1 followed different patterns for the different MSC populations. It was not significantly different than the expression of RUNX2. In contrast, the expression of MSI1 and POSTN and RUNX2 were statistically different in most MSC populations. Conclusion: In the current study, a similar expression pattern of MSI1 and RUNX2 during in vitro osteogenic differentiation was identified.

An Endogenous Anti-aging Factor, Sonic Hedgehog, Suppresses Endometrial Stem Cell Aging through SERPINB2

Endometrial stem cells are located in the basal layer of the endometrium, and they are responsible for the cyclic regeneration of the uterus during the menstrual cycle. Recent studies have revealed that recurrent pregnancy loss is associated with an age-related stem cell deficiency in the endometrium. Therefore, intensive study of endometrial stem cell aging may provide new insights for preventing recurrent pregnancy loss. Sonic hedgehog (SHH) signaling has been identified as a morphogen during the embryonic development processes. In addition to this canonical function, we found that the age-associated decline in regenerative potential in the endometrium may be due to decreased SHH-signaling integrity in local stem cells with aging. Importantly, the current study also showed that SHH activity clearly declines with aging both in vitro and in vivo, and exogenous SHH treatment significantly alleviates various aging-associated declines in multiple endometrial stem cell functions, suggesting that SHH may act as an endogenous anti-aging factor in human endometrial stem cells. Moreover, we found that stem cell senescence may enhance SERPINB2 expression, which in turn mediates the effect of SHH on alleviating senescence-induced endometrial stem cell dysfunctions, suggesting that SERPINB2 is a master regulator of SHH signaling during the aging process.

Sonic hedgehog signalling regulates the self-renewal and proliferation of skin-derived precursor cells in mice

OBJECTIVES

The sonic hedgehog (Shh) signalling pathway has an important role in the maintenance of various stem cells and organogenesis during development. However, the effect of Shh in skin-derived precursors (SKPs), which have the capacity for multipotency and self-renewal, is not yet clear. The present study investigated the effects of the Shh signalling pathway on the proliferation and self-renewal of murine SKPs (mSKPs).

METHODS

The Shh signalling pathway was activated by treatment with purmorphamine (Shh agonist) or recombinant Shh in mSKPs. Cyclopamine (Shh antagonist) or GANT-61 (Gli inhibitor) was used to inhibit the pathway. Western blot, qPCR, and immunofluorescence were used to analyse the expression of genes related to self-renewal, stemness, epithelial-mesenchymal transition (EMT) and the Shh signalling pathway. In addition, cell proliferation and apoptosis were examined.

RESULTS

Inhibiting the Shh signalling pathway reduced mSKP proliferation and sphere formation, but increased apoptosis. Activating this signalling pathway produced opposite results. The Shh signalling pathway also controlled the EMT phenotype in mSKPs. Moreover, purmorphamine recovered the self-renewal and proliferation of aged mSKPs.

CONCLUSION

Our results suggest that the Shh signalling pathway has an important role in the proliferation, self-renewal and apoptosis of mSKPs. These findings also provide a better understanding of the cellular mechanisms underlying SKP self-renewal and apoptosis that allow more efficient expansion of SKPs.

Increased Expression of Musashi-1 Evidences Mesenchymal Repair in Maxillary Sinus Floor Elevation

This study aimed to analyze the expression of Musashi-1 (MSI1) in maxillary native bone and grafted bone after maxillary sinus floor elevation. To do so, fifty-seven bone biopsies from 45 participants were studied. Eighteen samples were collected from native bone while 39 were obtained 6 months after maxillary sinus grafting procedures. Musashi-1 was analyzed by immunohistochemistry and RT-PCR. MSI1 was detected in osteoblasts and osteocytes in 97.4% (38/39) of grafted areas. In native bone, MSI1 was detected in only 66.6% (12/18) of the biopsies, mainly in osteocytes. Detection of MSI1 was significantly higher in osteoprogenitor mesenchymal cells of grafted biopsies (p < 0.001) but minor in smooth muscle and endothelial cells; no expression was detected in adipocytes. The mesenchymal cells of the non-mineralized tissue of native bone showed very low nuclear expression of MSI1, in comparison to fusiform cells in grafted areas (0.28(0.13) vs. 2.10(0.14), respectively; p < 0.001). Additionally, the detection of MSI1 mRNA was significantly higher in biopsies from grafted areas than those from native bone (1.00(0.51) vs. 60.34(35.2), respectively; p = 0.029). Thus, our results regardig the significantly higher detection of Musashi-1 in grafted sites than in native bone reflects its importance in the remodeling/repair events that occur after maxillary sinus floor elevation in humans.

A human patient-derived cellular model of Joubert syndrome reveals ciliary defects which can be rescued with targeted therapies

Joubert syndrome (JBTS) is the archetypal ciliopathy caused by mutation of genes encoding ciliary proteins leading to multi-system phenotypes, including a cerebello-retinal-renal syndrome. JBTS is genetically heterogeneous, however mutations in CEP290 are a common underlying cause. The renal manifestation of JBTS is a juvenile-onset cystic kidney disease, known as nephronophthisis, typically progressing to end-stage renal failure within the first two decades of life, thus providing a potential window for therapeutic intervention. In order to increase understanding of JBTS and its associated kidney disease and to explore potential treatments, we conducted a comprehensive analysis of primary renal epithelial cells directly isolated from patient urine (human urine-derived renal epithelial cells, hURECs). We demonstrate that hURECs from a JBTS patient with renal disease have elongated and disorganized primary cilia and that this ciliary phenotype is specifically associated with an absence of CEP290 protein. Treatment with the Sonic hedgehog (Shh) pathway agonist purmorphamine or cyclin-dependent kinase inhibition (using roscovitine and siRNA directed towards cyclin-dependent kinase 5) ameliorated the cilia phenotype. In addition, purmorphamine treatment was shown to reduce cyclin-dependent kinase 5 in patient cells, suggesting a convergence of these signalling pathways. To our knowledge, this is the most extensive analysis of primary renal epithelial cells from JBTS patients to date. It demonstrates the feasibility and power of this approach to directly assess the consequences of patient-specific mutations in a physiologically relevant context and a previously unrecognized convergence of Shh agonism and cyclin-dependent kinase inhibition as potential therapeutic targets.

Umbilical cord extracts improve osteoporotic abnormalities of bone marrow-derived mesenchymal stem cells and promote their therapeutic effects on ovariectomised rats

Bone marrow-derived mesenchymal stem cells (BM-MSCs) are the most valuable source of autologous cells for transplantation and tissue regeneration to treat osteoporosis. Although BM-MSCs are the primary cells responsible for maintaining bone metabolism and homeostasis, their regenerative ability may be attenuated in postmenopausal osteoporosis patients. Therefore, we first examined potential abnormalities of BM-MSCs in an oestrogen-deficient rat model constructed by ovariectomy (OVX-MSCs). Cell proliferation, mobilisation, and regulation of osteoclasts were downregulated in OVX-MSCs. Moreover, therapeutic effects of OVX-MSCs were decreased in OVX rats. Accordingly, we developed a new activator for BM-MSCs using human umbilical cord extracts, Wharton’s jelly extract supernatant (WJS), which improved cell proliferation, mobilisation and suppressive effects on activated osteoclasts in OVX-MSCs. Bone volume, RANK and TRACP expression of osteoclasts, as well as proinflammatory cytokine expression in bone tissues, were ameliorated by OVX-MSCs activated with WJS (OVX-MSCs-WJ) in OVX rats. Fusion and bone resorption activity of osteoclasts were suppressed in macrophage-induced and primary mouse bone marrow cell-induced osteoclasts via suppression of osteoclast-specific genes, such as Nfatc1, Clcn7, Atp6i and Dc-stamp, by co-culture with OVX-MSCs-WJ in vitro. In this study, we developed a new activator, WJS, which improved the functional abnormalities and therapeutic effects of BM-MSCs on postmenopausal osteoporosis.

Histopathological comparison of healing after maxillary sinus augmentation using xenograft mixed with autogenous bone versus allograft mixed with autogenous bone

OBJECTIVE

To compare the clinical and histologic outcomes of two different grafting materials (allograft and xenograft) when combined with autogenous bone and covered with a collagen membrane for sinus augmentation.

MATERIAL AND METHODS

A parallel case series of fourteen patients in need of a unilateral sinus augmentation was evaluated in this study. Seven patients received a graft composed by autologous cortical bone (ACB) and anorganic bovine bone in a ratio of 1:1; the other seven patients received ACB mixed with an allograft in the same ratio. Bone biopsies were obtained 6 months after sinus augmentation at the time of implant placement. Comparative histomorphometrical, histopathological, and immunohistochemical analyses were conducted and statistically analyzed.

RESULTS

After 12 months of functional loading, all implants in both groups were clinical and radiographically successful. Histomorphometrically, although the initial bone formation was not significantly different between groups (new mineralized tissue: 41.03(12.87)% vs. 34.50(13.18)%, p = .620; allograft vs. xenograft groups), the graft resorbed faster in the allograft group (remnant graft particles: 9.83[7.77]% vs. 21.71[17.88]%; p = .026; allograft vs. xenograft groups). Non-mineralized tissue did not statistically differ either (49.00[14.32]% vs. 43.79[19.90]%; p = .710; allograft vs. xenograft groups). The histologic analyses revealed higher cellular content, four times more osteoid lines, and higher vascularization in the xenograft group. Musashi-1 (mesenchymal stromal cell marker) was also more intensively expressed in the xenograft group (p = .019).

CONCLUSIONS

Both composite grafts generate adequate substratum to receive dental implants after healing. Compared with the xenograft composite, allograft composite shows faster turnover and a quicker decrease in biological action after 6 months.

Umbilical cord extracts improve diabetic abnormalities in bone marrow-derived mesenchymal stem cells and increase their therapeutic effects on diabetic nephropathy

Bone marrow-derived mesenchymal stem cells (BM-MSC) has been applied as the most valuable source of autologous cell transplantation for various diseases including diabetic complications. However, hyperglycemia may cause abnormalities in intrinsic BM-MSC which might lose sufficient therapeutic effects in diabetic patients. We demonstrated the functional abnormalities in BM-MSC derived from both type 1 and type 2 diabetes models in vitro, which resulted in loss of therapeutic effects in vivo in diabetic nephropathy (DN). Then, we developed a novel method to improve abnormalities in BM-MSC using human umbilical cord extracts, namely Wharton’s jelly extract supernatant (WJs). WJs is a cocktail of growth factors, extracellular matrixes and exosomes, which ameliorates proliferative capacity, motility, mitochondrial degeneration, endoplasmic reticular functions and exosome secretions in both type 1 and type 2 diabetes-derived BM-MSC (DM-MSC). Exosomes contained in WJs were a key factor for this activation, which exerted similar effects to complete WJs. DM-MSC activated by WJs ameliorated renal injury in both type 1 and type 2 DN. In this study, we developed a novel activating method using WJs to significantly increase the therapeutic effect of BM-MSC, which may allow effective autologous cell transplantation.

Hedgehog-Gli1 signaling regelates differentiation of chicken (Gallus gallus) embryonic stem cells to male germ cells

Gli1 is an important signaling molecular in Hedgehog signaling pathway. In our study, we explored the adjustment effect of Hedgehog-Gli1 signaling pathway on chicken male germ cells differentiation based on the transcriptome-wide analyses of chicken ESCs, primordial germ cells (PGCs) and spermatogonia stem cells (SSCs) that were associated with male germ cell differentiation. We screened out Hedgehog signaling pathway and identified 8 candidated differentially expressed genes (DEGs), Wnt3a, Wnt16, Wnt8a, HHIPL1, Gli1, BMP6, BMP7 and TTLL4. These DEGs expression change trend among blastoderm, genital ridge and testes, from which ESCs, PGCs and SSCs were isolated was the same as RNA-Seq data with quantitative RT-PCR evaluation. Based on retinoic acid (RA) induction of ESCs to SSCs in vitro, Gli1 overexpression has the ability to induce ESCs differentiation and SSCs-like cells formation and high expression of related reproductive genes, like Cvh, C-kit, Blamp1, Prmd14, Stra8, Dazl, integrin α6 and integrin β1 and so on in vitro. While RNAi knockdown of Gli1 can protect ESCs from differentiating into SSCs and correspondingly reduce the expression of the associated reproductive gene in vivo and vitro. Immunochemistry results showed that Gli1 overexpression could increase the expression of PGCs markers Cvh and C-kit and SSCs markers integrin α6 and integrin β1 in vivo, while Gli1 knockdown can have the opposite effect in vivo and in vitro. PAS stain and flow cytometry (FCM) evaluation results indicated the quantity of germ cells is decrease or increase with Gli1 knockdown or overexpression. Collectively, these results uncovered a novel function of Gli1 and demonstrated Hedgehog-Gli1 signaling pathway involved in chicken male germ cell differentiation, where it acts as a facilitator.

MiR-330-3p inhibits gastric cancer progression through targeting MSI1

Increasing evidences demonstrated that microRNAs (miRNAs) play critical roles in the human tumor development and progression. In our study, we found that miR-330-3p expression was downregulated in gastric cancer cell lines and tissues. Ectopic expression of miR-330-3p suppressed the gastric cancer cell proliferation, colony formation and migration. Overexpression of miR-330-3p promoted E-cadherin expression and inhibited the expression of N-cadherin, vimentin and snail. We identified Musashi-1 (MSI1) as a direct target gene of miR-330-3p in gastric cancer cell. In addition, MSI1 was upregulated in gastric cancer cell lines and tissues and the MSI1 expression was inversely correlated with miR-330-3p expression in gastric cancer tissues. MiR-330-3p expression was increased in gastric cancer cells after treated with histone deacetylase inhibitor trichostatin A (TSA) and DNA methylation inhibitor 5-aza-CdR (AZA). These indicated that downregulated expression of miR-330-3p was partly mediated by gene promoter region hypermethylation. These results suggested that miR-330-3p acted as a tumor suppressor gene in GC.

Msi1 promotes tumor growth and cell proliferation by targeting cell cycle checkpoint proteins p21, p27 and p53 in cervical carcinomas

Musashi RNA-binding protein1 (Msi1), a member of the RNA-binding protein family, has been reported to be a diagnostic marker and potential therapeutic target in some cancers, its function in cervical cancer remains unknown. In this study, we found Msi1 was highly expressed in cervical cancer tissues, and over-expressing Msi1 in cervical cancer cells enhanced tumor formation and cell proliferation and accelerated cells into the S phase. Whereas, down-regulating Msi1 by shRNA in cervical cancer cells inhibited tumor formation and cell proliferation and slowed cell into the S phase, suggesting that Msi1 might act as cell cycle regulator. Immunohistochemistry assay showed the negative correlation between Msi1 and p21, p27 and p53, suggesting that Msi1 might regulate these cycle regulators in cervical cancer. Moreover, the expression of the p21, p27 and p53 proteins were down-regulated in Msi1 overexpressing cervical cancer cells and up-regulated in shMsi1 cervical cancer cells. Luciferase assays and RNA-protein binding assays confirmed that Msi1 could bind to the mRNA 3′UTRs of p21, p27 and p53 and suppress the translation of these proteins. Our findings provide new evidence that Msi1 might promote cell proliferation by accelerating the cell cycle by directly targeting p21, p27 and p53.

Hedgehog and Resident Vascular Stem Cell Fate

The Hedgehog pathway is a pivotal morphogenic driver during embryonic development and a key regulator of adult stem cell self-renewal. The discovery of resident multipotent vascular stem cells and adventitial progenitors within the vessel wall has transformed our understanding of the origin of medial and neointimal vascular smooth muscle cells (SMCs) during vessel repair in response to injury, lesion formation, and overall disease progression. This review highlights the importance of components of the Hh and Notch signalling pathways within the medial and adventitial regions of adult vessels, their recapitulation following vascular injury and disease progression, and their putative role in the maintenance and differentiation of resident vascular stem cells to vascular lineages from discrete niches within the vessel wall.

RNA-binding protein Rbm47 binds to Nanog in mouse embryonic stem cells

Embryonic stem cells (ES cells) are pluripotent cells capable for self-renewal and to differentiate to all cell types. Finding the molecular mechanisms responsible for these unique characteristics of ES cells is important. RNA-binding proteins play important roles in post-transcriptional gene regulation by binding to specific mRNA targets. In this study, we investigated the targets of RNA-binding protein Rbm47 in mouse ES cells. Overexpression of HA epitope-tagged Rbm47 in mouse ES cells followed by RNA-binding protein immunoprecipitation, and then RT-PCR analysis of co-immunoprecipitated RNA showed that Rbm47 binds to Nanog transcript in mouse ES cells and doesn't bind to Sox2 and Oct4 transcripts in these cells. This finding can give rise to reveal molecular mechanisms underlying pluripotency and stemness of ES cells and will be necessary for efficient application of these cells in regenerative medicine and tissue engineering.