Sonic hedgehog increases the skin wound-healing ability of mouse embryonic stem cells through the microRNA 200 family

Fibrotic scar formation after cerebral ischemic stroke: Targeting the Sonic hedgehog signaling pathway for scar reduction

JOURNAL/nrgr/04.03/01300535-202602000-00044/figure1/v/2025-05-05T160104Z/r/image-tiff Recent studies have shown that fibrotic scar formation following cerebral ischemic injury has varying effects depending on the microenvironment. However, little is known about how fibrosis is induced and regulated after cerebral ischemic injury. Sonic hedgehog signaling participates in fibrosis in the heart, liver, lung, and kidney. Whether Shh signaling modulates fibrotic scar formation after cerebral ischemic stroke and the underlying mechanisms are unclear. In this study, we found that Sonic Hedgehog expression was upregulated in patients with acute ischemic stroke and in a middle cerebral artery occlusion/reperfusion injury rat model. Both Sonic hedgehog and Mitofusin 2 showed increased expression in the middle cerebral artery occlusion rat model and in vitro fibrosis cell model induced by transforming growth factor-beta 1. Activation of the Sonic hedgehog signaling pathway enhanced the expression of phosphorylated Smad 3 and Mitofusin 2 proteins, promoted the formation of fibrotic scars, protected synapses or promoted synaptogenesis, alleviated neurological deficits following middle cerebral artery occlusion/reperfusion injury, reduced cell apoptosis, facilitated the transformation of meninges fibroblasts into myofibroblasts, and enhanced the proliferation and migration of meninges fibroblasts. The Smad3 phosphorylation inhibitor SIS3 reversed the effects induced by Sonic hedgehog signaling pathway activation. Bioinformatics analysis revealed significant correlations between Sonic hedgehog and Smad3, between Sonic hedgehog and Mitofusin 2, and between Smad3 and Mitofusin 2. These findings suggest that Sonic hedgehog signaling may influence Mitofusin 2 expression by regulating Smad3 phosphorylation, thereby modulating the formation of early fibrotic scars following cerebral ischemic stroke and affecting prognosis. The Sonic Hedgehog signaling pathway may serve as a new therapeutic target for stroke treatment.

Type 3 deiodinase activation mediated by the Shh/Gli1 axis promotes sepsis-induced metabolic dysregulation in skeletal muscles

Background

Non-thyroidal illness syndrome is commonly observed in critically ill patients, characterized by the inactivation of systemic thyroid hormones (TH), which aggravates metabolic dysfunction. Recent evidence indicates that enhanced TH inactivation is mediated by the reactivation of type 3 deiodinase (Dio3) at the tissue level, culminating in a perturbed local metabolic equilibrium. This study assessed whether targeted inhibition of Dio3 can maintain tissue metabolic homeostasis under septic conditions and explored the mechanism behind Dio3 reactivation.

Methods

A retrospective clinical study was conducted to investigate the attributes of rT3. The expression of Dio3 was detected by immunoblotting, immunofluorescence, and immunohistochemical staining in tissues extracted from CLP-induced septic rats and human biopsy samples. In addition, the effect of Dio3 inhibition on skeletal muscle metabolism was observed in rats with targeted Dio3 knockdown using an adeno-associated virus. The effectiveness of Sonic hedgehog (Shh) signaling inhibition on systemic TH levels was observed in CLP-induced septic rats receiving cyclopamine. The mechanisms underlying such inhibition were explored using immunoblotting, RNA-seq, and chromatin immunoprecipitation-qPCR assays.

Results

The main product of Dio3, rT3, is strongly associated with organ function. Early sepsis leads to significant upregulation of Dio3 in the skeletal muscles and lung tissues of septic rats. The targeted inhibition of Dio3 in skeletal muscle restores TH responsiveness, prevents fast-to-slow fiber conversion, preserves glucose transporter type 4 functionality, and maintains metabolic balance between protein synthesis and proteolysis, which leads to preserved muscle mass. The reactivation of Dio3 is transcriptionally regulated by the Shh pathway induced by the signal transducer and activator of transcription 3.

Conclusions

The suppression of Dio3 restores tissue TH actions, attenuates proteolysis, and ameliorates anabolic resistance in the skeletal muscles of septic rats, thereby improving local metabolic homeostasis. Our results provide insights into the mechanisms of Dio3 reactivation and its critical role in local metabolic alterations induced by sepsis, while also suggesting novel targets aimed at ameliorating tissue-specific metabolic disorders.

Identification of miR-141 as a Regulator of Epidermal Homeostasis

MicroRNAs, small endogenous noncoding RNAs, are involved in the regulation of epidermal homeostasis. Among them, miR-203 was the most described and expressed in human epidermis, promoting keratinocyte (KC) differentiation by repressing genes involved in proliferation. To identify other microRNAs involved in this process, the miRNomes of normal human KCs cultured in monolayer (2-dimensional) or in 3-dimensional reconstructed skin were compared. Besides miR-203, miR-141 was one of the most expressed microRNAs in 3-dimensional culture and was overexpressed in 3-dimensional versus 2-dimensional condition, that is, during KC differentiation. Functional experiments revealed that, mostly expressed in the basal layer, miR-141 decreased KC proliferation and clonogenicity while promoting differentiation. Target prediction algorithm coupled with transcriptomic data of KCs overexpressing miR-141 as well as 3' untranslated region luciferase assays highlighted CCND2 mRNA as a direct target of miR-141, leading to its downregulation by miR-141 overexpression. Finally, CCND2 silencing decreased KC proliferation and induced differentiation, revealing that miR-141 action was mediated by CCND2. MiR-141 features were also compared with those of miR-203 in parallel experiments. Although miR-141 displayed functions similar to those of miR-203, it exhibited different localization and targets, suggesting a joint participation of miR-141 and miR-203 in engaging and maintaining KC toward differentiation, respectively.

Initial WNT/β-Catenin or BMP Activation Modulates Inflammatory Response of Mesodermal Progenitors Derived from Human Induced Pluripotent Stem Cells

Wound healing in adults largely depends on the functional state of multipotent mesenchymal stromal cells (MSCs). Human fetal tissues at the early stages of development are known to heal quickly with a full-quality restoration of the original structure. The differences in the molecular mechanisms that determine the functional activity of mesodermal cells in fetuses and adults remain virtually unknown. Using two independent human induced pluripotent stem cell (iPSC) lines, we examined the effects of the initial WNT and BMP activation on the differentiation of iPSCs via mesodermal progenitors into MSCs and highlighted the functions of these cells that are altered by the proinflammatory microenvironment. The WNT-induced mesoderm commitment of the iPSCs enhanced the expression of paraxial mesoderm (PM)-specific markers, while the BMP4-primed iPSCs exhibited increased levels of lateral mesoderm (LM)-specific genes. The inflammatory status and migration rate of the isogenic iPSC-derived mesoderm cells were assessed via gene expression analysis and scratch assay under the receptor-dependent activation of the proinflammatory IFN-γ or TNF-α signaling pathway. Reduced IDO1 and ICAM1 expression levels were detected in the WNT- and BMP-induced MSC progenitors compared to the isogenic MSCs in response to stimulation with IFN-γ and TNF-α. The WNT- and BMP-induced MSC progenitors exhibited a higher migration rate than isogenic MSCs upon IFN-γ exposure. The established isogenic cellular model will provide new opportunities to elucidate the mechanisms of regeneration and novel therapeutics for wound healing.

GLI family zinc finger protein 2 promotes skin fibroblast proliferation and DNA damage repair by targeting the miR-200/ataxia telangiectasia mutated axis in diabetic wound healing

Diabetic foot ulcer (DFU) is a serious complication of diabetic patients which negatively affects their foot health. This study aimed to estimate the role and mechanism of the miR-200 family in DNA damage of diabetic wound healing. Human foreskin fibroblasts (HFF-1 cells) were stimulated with high glucose (HG). Db/db mice were utilized to conduct the DFU in vivo model. Cell viability was evaluated using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assays. Superoxide dismutase activity was determined using detection kits. Reactive oxygen species determination was conducted via dichlorodihydrofluorescein-diacetate assays. Enzyme-linked immunosorbent assay was used to evaluate 8-oxo-7,8-dihydro-2'deoxyguanosine levels. Genes and protein expression were analyzed by quantitative real-time polymerase chain reaction, western blotting, or immunohistochemical analyses. Luciferase reporter gene and RNA immunoprecipitation assays determined the interaction with miR-200a/b/c-3p and GLI family zinc finger protein 2 (GLI2) or ataxia telangiectasia mutated (ATM) kinase. HG repressed cell proliferation and DNA damage repair, promoted miR-200a/b/c-3p expression, and suppressed ATM and GLI2. MiR-200a/b/c-3p inhibition ameliorated HG-induced cell proliferation and DNA damage repair repression. MiR-200a/b/c-3p targeted ATM. Then, the silenced ATM reversed the miR-200a/b/c-3p inhibition-mediated alleviative effects under HG. Next, GLI2 overexpression alleviated the HG-induced cell proliferation and DNA damage repair inhibition via miR-200a/b/c-3p. MiR-200a/b/c-3p inhibition significantly promoted DNA damage repair and wound healing in DFU mice. GLI2 promoted cell proliferation and DNA damage repair by regulating the miR-200/ATM axis to enhance diabetic wound healing in DFU.

Coexpression analysis of angiogenesis, proliferation, apoptosis, autophagy and SHH pathway genes involved in skin expansion

Skin and soft tissue expansion is a widely used technique in plastic surgery. However, the regulatory mechanisms associated with cellular processes involved in skin expansion are not well elucidated. In the present study, we aimed at exploring the transcriptome changes associated with skin expansion and profiling the difference in gene expression between the skin tissue in the top of the dilator and the skin tissue in the side of the dilator. A mouse model of skin expansion was established and RNA sequencing (RNA-Seq) was performed on samples collected at different time points. Differential expression analysis was performed using the DESeq2 package while STEM was used for time series clustering profiling. The regulatory networks were established and the functions of sets of genes were analyzed. The mRNA expression levels of candidate genes were validated by the quantitative RT-PCR. Among the skin tissue in the top of the dilator and normal samples at days 1, 3, 7, 14 and 28, 53 commonly upregulated and 7 commonly downregulated genes were identified while among the skin tissue in the side of the dilator and normal samples, 98 downregulated and 255 upregulated genes were identified. Genes differentially expressed among the skin tissue in the top of the dilator and normal samples were involved in coagulation and proliferation-associated pathways while those among the skin tissue in the side of the dilator and normal samples were involved in the inflammation, immune response, and defense response. Among the skin tissue in the top of the dilator and the skin tissue in the side of the dilator samples, 161 were constantly upregulated while 27 were constantly downregulated; these genes were enriched in the biological processes of cell adhesion and regulation of cell proliferation (n = 11). Furthermore, we identified that SHH signaling genes formed a coexpression regulatory network with cellular proliferation, apoptosis, autophagy and angiogenesis-related genes in the expanded skin. In conclusion, our findings can promote research and understanding of the mechanism of skin expansion and will find application in plastic surgery.

A novel sprayable thermosensitive hydrogel coupled with zinc modified metformin promotes the healing of skin wound

A novel sprayable adhesive is established (ZnMet-PF127) by the combination of a thermosensitive hydrogel (Pluronic F127, PF127) and a coordination complex of zinc and metformin (ZnMet). Here we demonstrate that ZnMet-PF127 potently promotes the healing of traumatic skin defect and burn skin injury by promoting cell proliferation, angiogenesis, collagen formation. Furthermore, we find that ZnMet could inhibit reactive oxygen species (ROS) production through activation of autophagy, thereby protecting cell from oxidative stress induced damage and promoting healing of skin wound. ZnMet complex exerts better effects on promoting skin wound healing than ZnCl₂ or metformin alone. ZnMet complex also displays excellent antibacterial activity against Staphylococcus aureus or Escherichia coli, which could reduce the incidence of skin wound infections. Collectively, we demonstrate that sprayable PF127 could be used as a new drug delivery system for treatment of skin injury. The advantages of this sprayable system are obvious: (1) It is convenient to use; (2) The hydrogel can cover irregular skin defect sites evenly in a liquid state. In combination with this system, we establish a novel sprayable adhesive (ZnMet-PF127) and demonstrate that it is a potential clinical treatment for traumatic skin defect and burn skin injury.

Sonic Hedgehog signalling in the regulation of barrier tissue homeostasis and inflammation

Epithelial barrier tissues such as the skin and airway form an essential interface between the mammalian host and its external environment. These physical barriers are crucial to prevent damage and disease from environmental insults and allergens. Failure to maintain barrier function against such risks can lead to severe inflammatory disorders, including atopic dermatitis and asthma. Here, we discuss the role of the morphogen Sonic Hedgehog in postnatal skin and lung and the impact of Shh signalling on repair, inflammation, and atopic disease in these tissues.

Emerging role of non-coding RNAs in the regulation of Sonic Hedgehog signaling pathway

Sonic Hedgehog (Shh) signaling cascade is one of the complex signaling pathways that control the accurately organized developmental processes in multicellular organisms. This pathway has fundamental roles in the tumor formation and induction of resistance to conventional therapies. Numerous non-coding RNAs (ncRNAs) have been found to interact with Shh pathway to induce several pathogenic processes, including malignant and non-malignant disorders. Many of the Shh-interacting ncRNAs are oncogenes whose expressions have been increased in diverse malignancies. A number of Shh-targeting miRNAs such as miR-26a, miR-1471, miR-129-5p, miR-361-3p, miR-26b-5p and miR-361-3p have been found to be down-regulated in tumor tissues. In addition to malignant conditions, Shh-interacting ncRNAs can affect tissue regeneration and development of neurodegenerative disorders. XIST, LOC101930370, lncRNA-Hh, circBCBM1, SNHG6, LINC‐PINT, TUG1 and LINC01426 are among long non-coding RNAs/circular RNAs that interact with Shh pathway. Moreover, miR-424, miR-26a, miR-1471, miR-125a, miR-210, miR-130a-5p, miR-199b, miR-155, let-7, miR-30c, miR-326, miR-26b-5p, miR-9, miR-132, miR-146a and miR-425-5p are among Shh-interacting miRNAs. The current review summarizes the interactions between ncRNAs and Shh in these contexts.

Revisiting the miR-200 Family: A Clan of Five Siblings with Essential Roles in Development and Disease

Over two decades of studies on small noncoding RNA molecules illustrate the significance of microRNAs (miRNAs/miRs) in controlling multiple physiological and pathological functions through post-transcriptional and spatiotemporal gene expression. Among the plethora of miRs that are essential during animal embryonic development, in this review, we elaborate the indispensable role of the miR-200 family (comprising miR-200a, -200b, 200c, -141, and -429) in governing the cellular functions associated with epithelial homeostasis, such as epithelial differentiation and neurogenesis. Additionally, in pathological contexts, miR-200 family members are primarily involved in tumor-suppressive roles, including the reversal of the cancer-associated epithelial-mesenchymal transition dedifferentiation process, and are dysregulated during organ fibrosis. Moreover, recent eminent studies have elucidated the crucial roles of miR-200s in the pathophysiology of multiple neurodegenerative diseases and tissue fibrosis. Lastly, we summarize the key studies that have recognized the potential use of miR-200 members as biomarkers for the diagnosis and prognosis of cancers, elaborating the application of these small biomolecules in aiding early cancer detection and intervention.

[Research advances on the role of competing endogenous RNAs in wound healing]

Wound healing, as one of the important public health issues, has been a worldwide problem. Due to the unique biological wound environment, wound healing is a very complex process with current treatments requiring long cycles, being poorly effective, and bringing high economic burden to patients. An increasing number of studies have shown that non-coding RNAs (ncRNAs) play important roles in wound healing process. The competing endogenous RNAs (ceRNAs) hypothesis in recent years is a new proposal on the inter-regulation of RNAs, which suggests a "mode of communication" between different RNAs. ceRNA regulatory network (ceRNET) combines the functions of protein-coding mRNA with ncRNA (e.g., microRNA, long non-coding RNA, pseudogenes, and circular RNA). Recent studies have shown that ceRNAs play important roles in wound healing, which may provide new effective therapeutic targets for wound healing. This paper starting with ceRNET systematically reviewed the research progress on the effects of various ceRNAs in wound healing and the future research challenges, with the aim to deeply explore the molecular mechanisms and clinical significance of ceRNAs in the process of wound healing.

Zinc finger E-Box binding homeobox 2 (ZEB2)-induced astrogliosis protected neuron from pyroptosis in cerebral ischemia and reperfusion injury

Ischemia injury can cause cell death or impairment of neuron and astrocytes, and thus induce loss of nerve function. central nervous systems injury induces an aberrant activation of astrocytes called astrogliosis. Pyroptosis, which is a kind of programmed cell death, was proved play an important role in ischemia injury. Zinc Finger E-Box Binding Homeobox 2 (ZEB2) promoted neuron astrogliosis, which play a protected role in neuron regeneration. However, its precise mechanism remains unclear. This study investigated the mechanism of ZEB2 on astrogliosis and neuron regeneration after cerebral ischemia reperfusion condition. To confirm our hypothesis, Neurons and astrocytes were isolated from fetal Sprague Dawley rats, in vivo Middle Cerebral Artery Occlusion/reperfusion (MCAO/R) rat model and in vitro oxygen-glucose deprivation/reperfusion (OGD/R)-treated astrocytes and neurocytes model were constructed. Our results showed that ZEB2 was expressed in nucleus of astrocyte and upregulated after OGD/R induction, ZEB2 promoted astrogliosis. Further upregulation of ZEB2 promoted the astrogliosis, which promoted neuron proliferation and regeneration by decreased pyroptosis. Moreover, this finding was further confirmed in vivo MCAO/R rat model. Overexpression of ZEB2 promoted astrogliosis, which decreased infarct volume and accumulated recovery of neurological function by alleviated pyroptosis. This finding revealed that ZEB2 was a regulator of the astrogliosis after ischemia/reperfusion injury, and then astrogliosis promoted neuron regeneration via decreased neuron pyroptosis. Therefore, ZEB2 may be a potential therapeutic target for ischemia/reperfusion injury.

Stem Cell Therapy for Burns: Story so Far

Burn injuries affect approximately 11 million people annually, with fatalities amounting up to 180,000. Burn injuries constitute a global health issue associated with high morbidity and mortality. Recent years have seen advancements in regenerative medicine for burn wound healing encompassing stem cells and stem cell-derived products such as exosomes and conditioned media with promising results compared to current treatment approaches. Sources of stem cells used for treatment vary ranging from hair follicle stem cells, embryonic stem cells, umbilical cord stem cells, to mesenchymal stem cells, such as adipose-derived mesenchymal stem cells, bone marrow-derived mesenchymal stem cells, and even stem cells harvested from discarded burn tissue. Stem cells utilize various pathways for wound healing, such as PI3/AKT pathway, WNT-β catenin pathway, TGF-β pathway, Notch and Hedgehog signaling pathway. Due to the paracrine signaling mechanism of stem cells, exosomes and conditioned media derived from stem cells have also been utilized in burn wound therapy. As exosomes and conditioned media are cell-free therapy and contain various biomolecules that facilitate wound healing, they are gaining popularity as an alternative treatment strategy with significant improvement in outcomes. The treatment is provided either as direct injections or embedded in a natural/artificial scaffold. This paper reviews in detail the different sources of stem cells, stem cell-derived products, their efficacy in burn wound repair, associated signaling pathways and modes of delivery for wound healing.

Skin wound healing assisted by angiogenic targeted tissue engineering: A comprehensive review of bioengineered approaches

Skin injuries and in particular, chronic wounds, are one of the major prevalent medical problems, worldwide. Due to the pivotal role of angiogenesis in tissue regeneration, impaired angiogenesis can cause several complications during the wound healing process and skin regeneration. Therefore, induction or promotion of angiogenesis can be considered as a promising approach to accelerate wound healing. This article presents a comprehensive overview of current and emerging angiogenesis induction methods applied in several studies for skin regeneration, which are classified into the cell, growth factor, scaffold, and biological/chemical compound-based strategies. In addition, the advantages and disadvantages of these angiogenic strategies along with related research examples are discussed in order to demonstrate their potential in the treatment of wounds.

miR-203a-3p promotes loureirin A-induced hair follicle stem cells differentiation by targeting Smad1

MicroRNAs (miRNAs) participate in the repair of skin trauma. Our previous study indicated that loureirin A promoted hair follicle stem cells (HFSCs) to repair skin epidermis. However, the mechanism of miRNA-mediated regulation of loureirin A-induced HFSC differentiation remained to be explored. In the present study, HFSCs from rat vibrissa were identified by immunofluorescence in vitro. Microarray and quantitative real time polymerase chain reaction analyses demonstrated that miR-203a-3p was upregulated in differentiated HFSCs induced by loureirin A. The expression of cytoskeletal keratin (CK) 5 and involucrin was promoted by miR-203a-3p mimics while repressed by a miR-203a-3p inhibitor. Smad1 was identified as a key target of miR-203a-3p using target prediction tools. Luciferase reporter gene test confirmed a special target association between miR-203a-3p and Smad1. Short interfering Smad1 was transfected into HFSCs, and the expression levels of CK5 and involucrin were upregulated. Thus, it can be inferred that miR-203a-3p negatively regulated the expression of Smad1 and promoted the differentiation of loureirin A-induced HFSCs. Bone morphogenetic protein (BMP) signal inhibition and Wnt activation coregulate skin injury repair. BMP/Smad1 signaling is involved in maintaining the characteristics of HFSCs and inhibiting their differentiation. Our results showed that miR-203a-3p reduces Smad1 to release BMP inhibition. Taken together, miR-203a-3p/Smad1 is a potential therapeutic molecular target in skin wound healing, and may play an active role in wound repair and regenerative medicine.

Modulation of sonic hedgehog-induced mouse embryonic stem cell behaviours through E-cadherin expression and integrin β1-dependent F-actin formation

BACKGROUND AND PURPOSE

The sonic hedgehog pathway (Shh) plays a central role in maintaining stem cell function and behaviour in various processes related to self-renewal and tissue regeneration. However, the therapeutic effect of Shh on mouse embryonic stem cells (mESCs) has not yet been clearly elucidated. Thus, we investigated the effect of Shh on the regulation of mESC behaviour as well as the effect of Shh-pretreated mESCs in skin wound healing.

EXPERIMENTAL APPROACH

The underlying mechanisms of Shh signalling pathway in growth and motility of mESCs were investigated using Western blot analysis, a cell proliferation assay and cell migration assay. In addition, the effect of Shh-pretreated mESCs in skin wound healing was determined using a mouse excisional wound splinting model.

KEY RESULTS

Shh disrupted the adherens junction through proteolysis by activating MMPs. In addition, the release of β-catenin from adherens junctions mediated by Shh led to cell cycle-dependent mESC proliferation. Shh-mediated Gli1 expression led to integrin β1 up-regulation, followed by FAK and Src phosphorylation. Furthermore, among the Rho-GTPases, Rac1 and Cdc42 were activated in a Shh-dependent manner while F-actin expression was suppressed by Rac1 and Cdc42 siRNA transfection. Consistent with the in vitro results, the skin wound healing assay revealed that Shh-treated mESCs increased angiogenesis and skin wound repair compared to that in Shh-treated mESCs transfected with integrin β1 siRNA in vivo.

CONCLUSIONS AND IMPLICATIONS

Our results imply that Shh induces adherens junction disruption and integrin β1-dependent F-actin formation by a mechanism involving FAK/Src and Rac1/Cdc42 signalling pathways in mESCs.

Expression and significance of the Hedgehog signal transduction pathway in oxygen-induced retinal neovascularization in mice

Aim

The aim of the study was to investigate the signal transduction mechanism of Hedgehog–vascular endothelial growth factor in oxygen-induced retinopathy (OIR) and the effects of cyclopamine on OIR.

Methods

An OIR model was established in C57BL/6J mice exposed to hyperoxia. Two hundred mice were randomly divided into a control group, an OIR group, an OIR-control group (treated with isometric phosphate-buffered saline by intravitreal injection), and a cyclopamine group (treated with cyclopamine by intravitreal injection), with 50 mice in each group. The retinal vascular morphology was observed using adenosine diphosphatase and number counting using hematoxylin and eosin-stained image. Quantitative real-time quantitative polymerase chain reaction was used to detect mRNA expression. Protein location and expression were evaluated using immunohistochemistry and Western blot.

Results

The OIR group and OIR-control group demonstrated large-area pathological neovascularization and nonperfused area when compared with the control group (both P<0.05). The area of nonperfusion and neovascularization in the cyclopamine group was significantly reduced compared with the OIR and OIR-control groups (both P<0.05). Compared with the control group, the OIR and OIR-control groups had more vascular endothelial cells breaking through the inner limiting membrane. The number of new blood vessel endothelial cell nuclei in the cyclopamine group was significantly reduced (both P<0.05) when compared with the OIR and OIR-control groups. The mRNA and protein expressions of Smoothened, Gli1, and vascular endothelial growth factor in the signal pathway of the OIR and OIR-control groups were significantly higher than those of the control group; however, in the cyclopamine group, these factors were reduced when compared with the OIR and OIR-control groups (all P<0.05).

Conclusion

Our data suggest that abnormal expression of the Hedgehog signaling pathway may be closely associated with the formation of OIR. Inhibiting the Smoothened receptor using cyclopamine could control retinal neovascularization, providing new ideas and measures for the prevention of oxygen-induced retinal neovascularization.

Succinate promotes stem cell migration through the GPR91-dependent regulation of DRP1-mediated mitochondrial fission

The role of metabolites produced from stem cell metabolism has been emerged as signaling molecules to regulate stem cell behaviors such as migration. The mitochondrial morphology is closely associated with the metabolic balance and stem cell function. However, the physiological role of succinate on human mesenchymal stem cell (hMSC) migration by regulating the mitochondrial morphology remains unclear. Here, we investigate the effect of succinate on hMSC migration via regulation of mitochondrial dynamics and its related signaling pathway. Succinate (50 μM) significantly accelerates hMSC migration. Succinate increases phosphorylation of pan-PKC, especially the atypical PKCζ level which was blocked by the knockdown of Gα_q and Gα_12. Activated PKCζ subsequently phosphorylates p38 MAPK. Cytosolic DRP1 is phosphorylated by p38 MAPK and results in DRP1 translocation to the mitochondria outer membrane, eventually inducing mitochondrial fragmentation. Mitochondrial fission-induced mitochondrial function elevates mitochondrial ROS (mtROS) levels and activates Rho GTPases, which then induces F-actin formation. Furthermore, in a skin excisional wound model, we found the effects of succinate-pretreated hMSC enhanced wound closure, vascularization and re-epithelialization and confirmed that DRP1 has a vital role in injured tissue regeneration. Overall, succinate promotes DRP1-mediated mitochondrial fission via GPR91, consequently stimulating the hMSC migration through mtROS-induced F-actin formation.

Aβ-Induced Drp1 phosphorylation through Akt activation promotes excessive mitochondrial fission leading to neuronal apoptosis

Mitochondrial dysfunction is known as one of causative factors in Alzheimer's disease (AD), inducing neuronal cell death. Mitochondria regulate their functions through changing their morphology. The present work was undertaken to investigate whether Amyloid β (Aβ) affects mitochondrial morphology in neuronal cells to induce apoptosis. Aβ treatment induced not only the fragmentation of mitochondria but also neuronal apoptosis in association with an increase in caspase-9 and -3 activity. Calcium influx induced by Aβ up-regulated the activation of Akt through CaMKII resulting in changes to the phosphorylation level of Drp1 in a time-dependent manner. Translocation of Drp1 from the cytosol to mitochondria was blocked by CB-124005 (an Akt inhibitor). Recruitment of Drp1 to mitochondria led to ROS generation and mitochondrial fission, accompanied by dysfunction of mitochondria such as loss of membrane potential and ATP production. ROS generation and mitochondrial dysfunction by Aβ were attenuated when treated with Mdivi-1, a selective Drp1 inhibitor. Furthermore, the sustained Akt activation induced not only the fragmentation of mitochondria but also the activation of mTOR, eventually suppressing autophagy. Inhibition of autophagic clearance of Aβ led to increased ROS levels and aggravating mitochondrial defects, which were blocked by Rapamycin (an mTOR inhibitor). In conclusion, sustained phosphorylation of Akt by Aβ directly activates Drp1 and inhibits autophagy through the mTOR pathway. Together, these changes elicit abundant mitochondrial fragmentation resulting in ROS-mediated neuronal apoptosis.

Sonic Hedgehog Signaling: Evidence for Its Protective Role in Endotoxin Induced Acute Lung Injury in Mouse Model

Objective

To investigate the protective role of the sonic hedgehog (SHH) signaling associated with a lipopolysaccharide (LPS)-induced acute lung injury (ALI) in a mouse model.

Methods

Male BALB/c mice were randomly divided into four groups: control, LPS, LPS-cyclopamine group and cyclopamine group. ALI was induced by LPS ip injection (5 mg/kg). The sonic hedgehog inhibitor cyclopamine (50 mg/kg) was given to the LPS-cyclopamine group at 30 min after LPS injection as well as normal mice as control. Lung injury was observed histologically in hematoxylin and eosin (HE) stained tissue sections, semi-quantified by lung tissue injury score, and the lung tissue mass alteration was measured by wet to dry weight ratio (W/D). mRNA expression levels of TNF-α, SHH, Patched (PTC) and GLI1 in lung tissue were studied with real time quantitative PCR (RT-PCR), while the protein expression of SHH and GLI1 was determined by western blot analysis.

Results

Lung tissue injury score, thickness of alveolar septa, W/D, and TNF-α mRNA expression levels were significantly higher in the ALI mice than the normal mice (P<0.05). The mRNA expression levels of SHH, PTC, and GLI1 in the ALI mice were significantly higher at 12h and 24h after LPS injection, but not at the 6h time point. Protein production of SHH and GLI1 at 6h, 12h, and 24h in the lungs of ALI mice significantly increased, in a time-dependent manner, compared with that in normal mice. Cyclopamine alone has no effect on pathological changes in normal mice. Intervention with cyclopamine in ALI mice led to a reduction in mRNA levels of SHH, PTC, and GLI1 as well as SHH and GLI1 protein levels; meanwhile, the pathological injury scores of lung tissues, thickness of alveolar septa, W/D, and mRNA expression levels of TNF-α increased compared with mice receiving LPS only.

Conclusion

The SHH signaling pathway was activated in response to LPS-induced ALI, and up-regulation of SHH expression could alleviate lung injury and be involved in the repair of injured lung tissue.

Epithelial-mesenchymal transition: An emerging target in tissue fibrosis

Epithelial-mesenchymal transition (EMT) is involved in a variety of tissue fibroses. Fibroblasts/myofibroblasts derived from epithelial cells contribute to the excessive accumulation of fibrous connective tissue in damaged tissue, which can lead to permanent scarring or organ malfunction. Therefore, EMT-related fibrosis cannot be neglected. This review highlights the findings that demonstrate the EMT to be a direct contributor to the fibroblast/myofibroblast population in the development of tissue fibrosis and helps to elucidate EMT-related anti-fibrotic strategies, which may enable the development of therapeutic interventions to suppress EMT and potentially reverse organ fibrosis.