Recent Insights into Long Bone Development: Central Role of Hedgehog Signaling Pathway in Regulating Growth Plate

Comparative population genomics analysis for chicken body sizes using genome-wide single nucleotide polymorphisms

OBJECTIVE

This study aims to investigate the selection history, genome regions, and candidate genes associated with different chicken body sizes, thereby providing insights into the genetic basis of complex economic traits such as chicken body size and growth.

METHODS

In this study, a total of 217 individuals from eight breeds were selected. According to body size, they were divided into two groups: large chickens and bantam chickens, with four breeds in each group. Firstly, we investigate population structure by principal component analysis (PCA), phylogenetic tree, and ancestry component analysis. Next, we recognize runs of homozygosity (ROH) islands through calculating ROH. Finally, we carry out selection signatures analysis utilizing population differentiation index and nucleic acid diversity.

RESULTS

The population structure analysis show that large and bantam chickens are clearly separated. Large chickens are clustered together, the bantam chickens are relatively dispersed. The results of ROH island analysis show that 48 and 56 ROH islands were identified in large and bantam chickens respectively. Among the interesting ROH islands, a total of eight candidate genes were identified. In selection signatures analysis, a total of 322 selected genes were annotated in large chickens, such as POU1F1, BMP10, enrichment in 16 gene ontology (GO) terms. In bantam chickens, a total of 447 selected genes were annotated, such as IGF1, GRB10, enrichment in 20 GO terms and 2 Kyoto encyclopedia of genes and genomes pathways. The haplotype analysis results show that GRB10 has differences in chickens of different body sizes.

CONCLUSION

By population structure, ROH islands, and selection signatures analysis, we have identified multiple genes associated with chicken body size, growth, and development (such as BMP10, IGF1, GRB10, etc). This provides a theoretical reference for the subsequent development of molecular markers for chicken body size and the analysis of the genetic mechanism of chicken body size.

The Shh-p38-NFATc1 signaling pathway is essential for osteoclastogenesis during tooth eruption

Tooth eruption, a critical stage in tooth development, is related to osteoclastogenesis. Intraperitoneal injection of Shh agonists into neonatal mice promoted tooth eruption at postnatal day (PN) 15, whereas treatment with the Shh inhibitor (LDE225) suppressed this process. When RAW264.7 osteoclast precursor cells were treated with RANKL, NFATc1 translocated from the cytoplasm to the nucleus and induced cell differentiation into TRAP+ osteoclasts; this process was activated by Shh but inhibited by LDE225. Treating RAW264.7 cells with the p38 inhibitor, BIRB796, also inhibited NFATc1 nuclear localization. p-p38 expression in the alveolar bone of PN3 and PN5 mice was decreased by treatment with LDE225, and RAW264.7 cell differentiation was reduced by BIRB796, regardless of treatment with Shh. Furthermore, Shh activated p38 signaling pathway in RAW264.7 cells, while p38 phosphorylation was reduced by LDE225, which ultimately inhibited osteoclast precursor differentiation. Therefore, we concluded that Shh promotes osteoclast precursor differentiation via the p38-NFATc1 signaling pathway.

Ghrelin alleviated TiO2 NPs-induced inhibition of endochondral osteogenesis and promoted longitudinal growth of long bones in juvenile rats via Wnt/β-catenin signaling pathway

Titanium dioxide nanoparticles (TiO2 NPs) are widely used in children's daily necessities and foods, and their health hazards to children have attracted particular attention. Childhood is a critical time for accelerated bone growth and development. Current studies revealed that TiO2 NPs exposure causes bone damage in juvenile rats; however, the underlying mechanism is unknown. Ghrelin is a polypeptide hormone that is considered to be a candidate factor for regulating bone growth and development. In this research, 3-week-old juvenile male rats were administered 0, 100 or 200 mg/kg TiO2 NPs and 50 μg/kg ghrelin for 4 weeks to explore the underlying mechanism of TiO2 NPs-induced bone damage, and the protective effect of ghrelin. Our results revealed that TiO2 NPs resulted in decreased synthesis of bone growth-related hormones, disturbed bone metabolism, and destruction of bone structure. Further mechanism studies showed that TiO2 NPs inhibited Wnt/β-catenin pathway, reduced collagen synthesis, inhibited chondrocyte proliferation and differentiation, promoted chondrocyte apoptosis, and inhibited endochondral osteogenesis, ultimately leading to long bone longitudinal growth retardation and osteoporosis. Ghrelin alleviated the negative effects of TiO2 NPs-induced bone growth in juvenile rats by upregulating the Wnt/β-catenin signaling pathway. This study provided a reference for the clinical treatment of growth retardation and idiopathic short stature in juvenile children caused by environmental pollutants.

Sonic hedgehog (shh) gene from Pseudopleuronectes yokohamae (Teleostei: Pleuronectidae): Molecular cloning, characterization, and expression profile during early embryonic, juvenile, and adult stages

The hedgehog signaling pathway plays an important role in early development and growth of most vertebrates. Sonic hedgehog (shh) gene is a critical regulator of embryonic development in many species, including humans. However, it is not clear what roles shh can play in the development of fish. In this paper, shh gene was cloned from Pseudopleuronectes yokohamae. The full-length complementary DNA (cDNA) of P. yokohamae sonic hedgehog gene (Pyshh) comprises 3194 bp, with a 1317-bp open reading frame (ORF) that encodes a polypeptide of 438 amino acids with a typical HH-signal domain and Hint-N domain. The conserved sequences of the protein among species were predicted by using multiple sequence comparison. The phylogenetic tree construction showed that PySHH is clustered in a branch of Pleuronectidae. To explore the expression of Pyshh gene in various tissues of P. yokohamae, we used real-time fluorescence quantitative PCR technology to detect it. The results showed that Pyshh gene is widely distributed in various tissues of P. yokohamae juveniles, different tissues of adult males and females, and is particularly expressed in immune organs. The Pyshh gene expression was higher in the muscle and brain of juvenile fish, and higher in bone, gill, and skin of male fish than that of female fish, suggesting that Pyshh might be involved in the formation of immune organs of P. yokohamae. The expression of Pyshh gene significantly upregulated from the gastrula stage to the hatching stage. Western blotting of the expression levels of PySHH during different embryonic development stages revealed that PySHH levels increased gradually during development stages from oosperm stage to hatching stage. These results indicate that Pyshh is highly conserved among species and plays a critical role in the complex process of embryonic development. Its precise regulation is essential for the proper formation of many organs and tissues in the body, and disruptions in its function may have serious consequences for the formation of immune organs in fish.

Maternal F-53B exposure during pregnancy and lactation affects bone growth and development in male offspring

6:2 Chlorinated polyfluoroalkyl ether sulfonate (F-53B) is a new type of perfluorinated and polyfluoroalkyl substance (PFAS) that is used extensively in industry and manufacturing. F-53B causes damage to multiple mammalian organs. However, the impacts of F-53B on bone are unknown. Maternal exposure to F-53B is of particular concern because of the vulnerability of the developing fetus and newborn to contaminants from the mother. The goal of this study was to examine the impacts of maternal F-53B exposure on bone growth and development in offspring and to explore its underlying mechanisms. Herein, C57BL/6 J mice were given free access to deionized water containing 0, 0.57, or 5.7 mg/L F-53B during pregnancy and lactation. F-53B exposure resulted in impaired liver function, decreased IGF-1 secretion, dysregulation of bone metabolism and disruption of the dynamic balance between osteoblasts and osteoclasts in male offspring. F-53B inhibits longitudinal bone growth and development and causes osteoporosis in male offspring. F-53B may affect the growth and development of offspring bone via the IGF-1/OPG/RANKL/CTSK signaling pathway. This study provides new insights for the study of short stature and bone injury caused by F-53B.

Brain-Derived Neurotrophic Factor - The Protective Agent Against Neurological Disorders

The burden of neurological illnesses on global health is significant. Our perception of the molecular and biological mechanisms underlying intellectual processing and behavior has significantly advanced over the last few decades, laying the groundwork for potential therapies for various neurodegenerative diseases. A growing body of literature reveals that most neurodegenerative diseases could be due to the gradual failure of neurons in the brain's neocortex, hippocampus, and various subcortical areas. Research on various experimental models has uncovered several gene components to understand the pathogenesis of neurodegenerative disorders. One among them is the brain-derived neurotrophic factor (BDNF), which performs several vital functions, enhancing synaptic plasticity and assisting in the emergence of long-term thoughts. The pathophysiology of some neurodegenerative diseases, including Alzheimer's, Parkinson's, Schizophrenia, and Huntington's, has been linked to BDNF. According to numerous research, high levels of BDNF are connected to a lower risk of developing a neurodegenerative disease. As a result, we want to concentrate on BDNF in this article and outline its protective role against neurological disorders.

Signaling Mechanisms of Stem Cell Therapy for Intervertebral Disc Degeneration

Low back pain is the leading cause of disability worldwide. Intervertebral disc degeneration (IDD) is the primary clinical risk factor for low back pain and the pathological cause of disc herniation, spinal stenosis, and spinal deformity. A possible approach to improve the clinical practice of IDD-related diseases is to incorporate biomarkers in diagnosis, therapeutic intervention, and prognosis prediction. IDD pathology is still unclear. Regarding molecular mechanisms, cellular signaling pathways constitute a complex network of signaling pathways that coordinate cell survival, proliferation, differentiation, and metabolism. Recently, stem cells have shown great potential in clinical applications for IDD. In this review, the roles of multiple signaling pathways and related stem cell treatment in IDD are summarized and described. This review seeks to investigate the mechanisms and potential therapeutic effects of stem cells in IDD and identify new therapeutic treatments for IDD-related disorders.

Inhibition of Ezh2 redistributes bivalent domains within transcriptional regulators associated with WNT and Hedgehog pathways in osteoblasts

Bivalent epigenomic regulatory domains containing both activating histone 3 lysine 4 (H3K4me3) and repressive lysine 27 (H3K27me3) trimethylation are associated with key developmental genes. These bivalent domains repress transcription in the absence of differentiation signals but maintain regulatory genes in a poised state to allow for timely activation. Previous studies demonstrated that enhancer of zeste homolog 2 (Ezh2), a histone 3 lysine 27 (H3K27) methyltransferase, suppresses osteogenic differentiation and that inhibition of Ezh2 enhances commitment of osteoblast progenitors in vitro and bone formation in vivo. Here, we examined the mechanistic effects of Tazemetostat (EPZ6438), an Food and Drug Administration approved Ezh2 inhibitor for epithelioid sarcoma treatment, because this drug could potentially be repurposed to stimulate osteogenesis for clinical indications. We find that Tazemetostat reduces H3K27me3 marks in bivalent domains in enhancers required for bone formation and stimulates maturation of MC3T3 preosteoblasts. Furthermore, Tazemetostat activates bivalent genes associated with the Wingless/integrated (WNT), adenylyl cyclase (cAMP), and Hedgehog (Hh) signaling pathways based on transcriptomic (RNA-seq) and epigenomic (chromatin immunoprecipitation [ChIP]-seq) data. Functional analyses using selective pathway inhibitors and silencing RNAs demonstrate that the WNT and Hh pathways modulate osteogenic differentiation after Ezh2 inhibition. Strikingly, we show that loss of the Hh-responsive transcriptional regulator Gli1, but not Gli2, synergizes with Tazemetostat to accelerate osteoblast differentiation. These studies establish epigenetic cooperativity of Ezh2, Hh-Gli1 signaling, and bivalent regulatory genes in suppressing osteogenesis. Our findings may have important translational ramifications for anabolic applications requiring bone mass accrual and/or reversal of bone loss.

The Emerging Role of Cell Transdifferentiation in Skeletal Development and Diseases

The vertebrate musculoskeletal system is known to be formed by mesenchymal stem cells condensing into tissue elements, which then differentiate into cartilage, bone, tendon/ligament, and muscle cells. These lineage-committed cells mature into end-stage differentiated cells, like hypertrophic chondrocytes and osteocytes, which are expected to expire and to be replaced by newly differentiated cells arising from the same lineage pathway. However, there is emerging evidence of the role of cell transdifferentiation in bone development and disease. Although the concept of cell transdifferentiation is not new, a breakthrough in cell lineage tracing allowed scientists to trace cell fates in vivo. Using this powerful tool, new theories have been established: (1) hypertrophic chondrocytes can transdifferentiate into bone cells during endochondral bone formation, fracture repair, and some bone diseases, and (2) tendon cells, beyond their conventional role in joint movement, directly participate in normal bone and cartilage formation, and ectopic ossification. The goal of this review is to obtain a better understanding of the key roles of cell transdifferentiation in skeletal development and diseases. We will first review the transdifferentiation of chondrocytes to bone cells during endochondral bone formation. Specifically, we will include the history of the debate on the fate of chondrocytes during bone formation, the key findings obtained in recent years on the critical factors and molecules that regulate this cell fate change, and the role of chondrocyte transdifferentiation in skeletal trauma and diseases. In addition, we will also summarize the latest discoveries on the novel roles of tendon cells and adipocytes on skeletal formation and diseases.

Novel large deletion involving EVC and EVC2 in Ellis-van Creveld syndrome

Ellis-van Creveld syndrome is an autosomal recessive skeletal dysplasia that is characterized by thoracic hypoplasia, polydactyly, oral abnormalities, and congenital heart disease. It is caused by pathogenic variants in the EVC or EVC2 genes. We report a case of a newborn with a compound heterozygous variant comprising NM_147127.5: c.1991dup:[p.Lys665Glufs*10] in the EVC2 gene and a novel large deletion involving exon 1 in EVC and exons 1-7 in EVC2.

The Emerging Role of OTUB2 in Diseases: From Cell Signaling Pathway to Physiological Function

Ovarian tumor (OTU) domain-containing ubiquitin aldehyde-binding protein Otubain2 (OTUB2) was a functional cysteine protease in the OTU family with deubiquitinase activity. In recent years, with the wide application of molecular biology techniques, molecular mechanism regulation at multiple levels of cell signaling pathways has been gradually known, such as ubiquitin-mediated protein degradation and phosphorylation-mediated protein activation. OTUB2 is involved in the deubiquitination of many key proteins in different cell signaling pathways, and the effect of OTUB2 on human health or disease is not clear. OTUB2 is likely to cause cancer and other malignant diseases while maintaining normal human development and physiological function. Therefore, it is of great value to comprehensively understand the regulatory mechanism of OTUB2 and regard it as a target for the treatment of diseases. This review makes a general description and appropriate analysis of OTUB2's regulation in different cell signaling pathways, and connects OTUB2 with cancer from the research hotspot perspective of DNA damage repair and immunity, laying the theoretical foundation for future research.

A Na+/K+ ATPase Pump Regulates Chondrocyte Differentiation and Bone Length Variation in Mice

The genetic and developmental mechanisms involved in limb formation are relatively well documented, but how these mechanisms are modulated by changes in chondrocyte physiology to produce differences in limb bone length remains unclear. Here, we used high throughput RNA sequencing (RNAseq) to probe the developmental genetic basis of variation in limb bone length in Longshanks, a mouse model of experimental evolution. We find that increased tibia length in Longshanks is associated with altered expression of a few key endochondral ossification genes such as Npr3, Dlk1, Sox9, and Sfrp1, as well reduced expression of Fxyd2, a facultative subunit of the cell membrane-bound Na⁺/K⁺ ATPase pump (NKA). Next, using murine tibia and cell cultures, we show a dynamic role for NKA in chondrocyte differentiation and in bone length regulation. Specifically, we show that pharmacological inhibition of NKA disrupts chondrocyte differentiation, by upregulating expression of mesenchymal stem cell markers (Prrx1, Serpina3n), downregulation of chondrogenesis marker Sox9, and altered expression of extracellular matrix genes (e.g., collagens) associated with proliferative and hypertrophic chondrocytes. Together, Longshanks and in vitro data suggest a broader developmental and evolutionary role of NKA in regulating limb length diversity.

OFD Type I syndrome: lessons learned from a rare ciliopathy

The OFD1 gene was initially identified as the gene responsible for the X-linked dominant male lethal OFD type I syndrome, a developmental disorder ascribed to cilia disfunction. The transcript has been subsequently associated to four different X-linked recessive conditions, namely Joubert syndrome, retinitis pigmentosa, primary ciliary dyskinesia and Simpson-Golabi-Behmel type 2 syndrome. The centrosomal/basal body OFD1 protein has indeed been shown to be required for primary cilia formation and left-right asymmetry. The protein is also involved in other tasks, e.g. regulation of cellular protein content, constrain of the centriolar length, chromatin remodeling at DNA double strand breaks, control of protein quality balance and cell cycle progression, which might be mediated by non-ciliary activities. OFD1 represents a paradigmatic model of a protein that performs its diverse actions according to the cell needs and depending on the subcellular localization, the cell type/tissue and other possible factors still to be determined. An increased number of multitask protein, such as OFD1, may represent a partial explanation to human complexity, as compared with less complex organisms with an equal or slightly lower number of proteins.

Wdpcp regulates cellular proliferation and differentiation in the developing limb via hedgehog signaling

Background

Mice with a loss of function mutation in Wdpcp were described previously to display severe birth defects in the developing heart, neural tube, and limb buds. Further characterization of the skeletal phenotype of Wdpcp null mice was limited by perinatal lethality.

Results

We utilized Prx1-Cre mice to generate limb bud mesenchyme specific deletion of Wdpcp. These mice recapitulated the appendicular skeletal phenotype of the Wdpcp null mice including polydactyl and limb bud signaling defects. Examination of late stages of limb development demonstrated decreased size of cartilage anlagen, delayed calcification, and abnormal growth plates. Utilizing in vitro assays, we demonstrated that loss of Wdpcp in skeletal progenitors lead to loss of hedgehog signaling responsiveness and associated proliferative response. In vitro chondrogenesis assays showed this loss of hedgehog and proliferative response was associated with decreased expression of early chondrogenic marker N-Cadherin. E14.5 forelimbs demonstrated delayed ossification and expression of osteoblast markers Runx2 and Sp7. P0 growth plates demonstrated loss of hedgehog signaling markers and expansion of the hypertrophic zones of the growth plate. In vitro osteogenesis assays demonstrated decreased osteogenic differentiation of Wdpcp null mesenchymal progenitors in response to hedgehog stimulation.

Conclusions

These findings demonstrate how Wdpcp and associated regulation of the hedgehog signaling pathway plays an important role at multiple stages of skeletal development. Wdpcp is necessary for positive regulation of hedgehog signaling and associated proliferation is key to the initiation of chondrogenesis. At later stages, Wdpcp facilitates the robust hedgehog response necessary for chondrocyte hypertrophy and osteogenic differentiation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12861-021-00241-9.

DESARROLLO Y CRECIMIENTO FEMORAL DE CONEJAS DE LA LÍNEA NEW ZEALAND

En este proyecto se investigan los cambios que acontecen en el desarrollo y crecimiento de conejos hembras de la línea New Zealand (CoNZ) en sus huesos femorales. Los animales fueron mantenidas en jaulas individuales desde las 2 semanas de edad, con comida  y agua ad libitum y se sacrificaron en tiempos mensualmente consecutivos: 1, 2, 3, 4, 5, y 6 meses. Tras la obtención de las piezas femorales, y a partir de estudios imagenológicos se  determinaron los ángulos del cuello femoral (Af), la longitud total (L), la densidad mineral ósea total, del centro óseo y de la metáfisis femoral (DMOt, DMOco y DMOmf respectivamente), analizándose las variaciones intergrupales por el test Wilcoxon, y corrección de Bonferroni. Se realizaron estudios histológicos de los cortes descalcificados de las piezas femorales. Los análisis sobre los Af mostraron un incremento significativo durante el primer mes mientras que L se estabilizó a partir del 4to mes. Los valores de DMOt mostraron un plateau a partir del cuarto mes, si bien las DMOco y DMOmf ya a partir del tercer mes no mostraron incrementos significativos. Histológicamente se observó para el cuarto mes ausencia de las diferentes zonas características del cartílago de crecimiento metafisiario, con presencia únicamente de un pequeño remanente de células condrales. Desde el quinto mes se observa ausencia total de cartílago, con presencia únicamente de tejido osteoide (TO). La interpretación integrada de los resultados nos permite afirmar, que a partir del cuarto mes de desarrollo, el fémur de CoNZ adquiere características compatibles con un periodo de adultez.

Smoothened inhibition leads to decreased cell proliferation and suppressed tissue fibrosis in the development of benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is a common disease in aging males. It has been proven that the Hedgehog (HH) is implied as an effective and fundamental regulatory growth factor signal for organogenesis, homeostasis, and regeneration. Smoothened (SMO), as the major control point of HH signals, activates aberrantly in most human solid tumors. However, the specific function of SMO and its downstream glioma-associated oncogene (GLI) family in BPH has not been well understood. Here, we first revealed that the SMO cascade was upregulated in BPH tissues and was localized in both the stromal and the epithelium compartments of human prostate tissues. Cyclopamine, as a specific SMO inhibitor, was incubated with BPH-1 and WPMY-1, and intraperitoneally injected into a BPH rat model established by castration with testosterone supplementation. SMO inhibition could induce cell apoptosis, cell cycle arrest at the G0/G1 phase, and a reduction of tissue fibrosis markers, both in vitro and in vivo. Finally, a tissue microarray, containing 104 BPH specimens, was constructed to analyze the correlations between the expression of SMO cascade and clinical parameters. The GLI2 was correlated positively with nocturia and negatively with fPSA. The GLI3 was in a positive relationship with International Prostate Symptom Score and nocturia. In conclusion, our study suggested that SMO cascade could play important roles in the development of BPH and it might be rediscovered as a promising therapeutic target for BPH.

Statins repress hedgehog signaling in medulloblastoma with no bone toxicities

The Hedgehog (Hh) pathway plays an indispensable role in bone development and genetic activation of the pathway results in medulloblastoma (MB), the most common malignant brain tumor in children. Inhibitors of Hh pathway (such as vismodegib and sonedigib), which are used to treat MB, cause irreversible defects in bone growth in young children. Cholesterol is required for the activation of the Hh pathway, and statins, inhibitors of cholesterol biosynthesis, suppress MB growth by repressing Hh signaling in tumor cells. Here, we investigate the role of cholesterol biosynthesis in the proliferation and Hh signaling in chondrocytes, and examine the bone development in mice after statin treatment. Statins significantly inhibited MB growth in young mice, but caused no defects in bone development. Conditional deletion of NADP steroid dehydrogenase-like (NSDHL), an enzyme necessary for cholesterol biosynthesis, suppressed cholesterol synthesis in chondrocytes, and disrupted the growth plate in mouse femur and tibia, indicating the important function of intracellular cholesterol in bone development. Hh pathway activation and the proliferation of chondrocytes were inhibited by statin treatment in vitro; however, statins did not impair bone growth in vivo due to insufficient penetration into the bone. Our studies reveal a critical role of cholesterol in bone development, and support the utilization of statins for treatment of MB as well as other Hh pathway-associated malignancies.

Menaquinone-7 Supplementation Improves Osteogenesis in Pluripotent Stem Cell Derived Mesenchymal Stem Cells

Development of clinical stem cell interventions are hampered by immature cell progeny under current protocols. Human mesenchymal stem cells (hMSCs) are characterized by their ability to self-renew and differentiate into multiple lineages. Generating hMSCs from pluripotent stem cells (iPSCs) is an attractive avenue for cost-efficient and scalable production of cellular material. In this study we generate mature osteoblasts from iPSCs using a stable expandable MSC intermediate, refining established protocols. We investigated the timeframe and phenotype of cells under osteogenic conditions as well as the effect of menaquinone-7 (MK-7) on differentiation. From day 2 we noted a significant increase in RUNX2 expression under osteogenic conditions with MK-7, as well as decreases in ROS species production, increased cellular migration and changes to dynamics of collagen deposition when compared to differentiated cells that were not treated with MK-7. At day 21 OsteoMK-7 increased alkaline phosphatase activity and collagen deposition, as well as downregulated RUNX2 expression, suggesting to a mature cellular phenotype. Throughout we note no changes to expression of osteocalcin suggesting a non-canonical function of MK-7 in osteoblast differentiation. Together our data provide further mechanistic insight between basic and clinical studies on extrahepatic activity of MK-7. Our findings show that MK-7 promotes osteoblast maturation thereby increasing osteogenic differentiation.

miR-143 is implicated in growth plate injury by targeting IHH in precartilaginous stem cells

Precartilaginous stem cells (PCSCs) are able to initiate chondrocyte and bone development. The present study aimed to investigate the role of miR-143 and the underlying mechanisms involved in PCSC proliferation. In a rat growth plate injury model, tissue from the injury site was collected and the expression of miR-143 and its potential targets was determined. PCSCs were isolated from the rabbits' distal epiphyseal growth plate. Cell viability, DNA synthesis, and apoptosis were determined with MTT, BrdU, and flow cytometric analysis, respectively. Real time PCR and western blot were performed to detect the mRNA and protein expression of the indicated genes. Indian hedgehog (IHH) was identified as a target gene for miR-143 with luciferase reporter assay. Decreased expression of miR-143 and increased expression of IHH gene were observed in the growth plate after injury. miR-143 mimics decreased cell viability and DNA synthesis and promoted apoptosis of PCSCs. Conversely, siRNA-mediated inhibition of miR-143 led to increased growth and suppressed apoptosis of PCSCs. Transfection of miR-143 decreased luciferase activity of wild-type IHH but had no effect when the 3'-UTR of IHH was mutated. Furthermore, the effect of miR-143 overexpression was neutralized by overexpression of IHH. Our study showed that miR-143 is involved in growth plate behavior and regulates PCSC growth by targeting IHH, suggesting that miR-143 may serve as a novel target for PCSC-related diseases.

Comparative transcriptome analyses and identification of candidate genes involved in vertebral abnormality of bighead carp Hypophthalmichthys nobilis

Body deformity occurs both in wild and farmed fishes, which is one of the most challenging problems for aquaculture industry. In most cases, such body deformities are linked to skeletal deformities. Currently, very limited information is available on skeletal deformities of farmed fish species which may be caused by genetic factor. In this study, we performed muscle and vertebra transcriptome analyses in body deformity and normality of bighead carp Hypophthalmichthys nobilis (from one meiotic gynogenesis family) using RNA-Seq. A total of 43,923 and 44,416 unigenes were predicted in muscles and vertebrae, respectively. Based on these data, we further explored the gene expression profiles in gynogenetic normal and abnormal bighead carp. No differentially expressed gene (DEG) was found in transcriptome data of muscles. Totally, 20 key DEGs were identified in transcriptome data of vertebrae, such as low density lipoprotein-related protein 2 (lrp2), bone morphogenetic protein 2B (bmp2b) and collagen alpha-1(IV) (col4a1). 12 potential pathways were also identified in vertebra transcriptome data, which were mainly involved in development, growth, cytoskeleton and energy metabolism, such as MAPK signaling pathway, regulation of actin cytoskeleton and TGF-beta signaling pathway. Results of this study will be informative for the understanding of genetic mechanisms for body shape formation and also provide potential candidate genes for selection program involved in body shape and skeletal development in H. nobilis.

Hedgehog Signaling in Skeletal Development: Roles of Indian Hedgehog and the Mode of Its Action

Hedgehog (Hh) signaling is highly conserved among species and plays indispensable roles in various developmental processes. There are three Hh members in mammals; one of them, Indian hedgehog (Ihh), is expressed in prehypertrophic and hypertrophic chondrocytes during endochondral ossification. Based on mouse genetic studies, three major functions of Ihh have been proposed: (1) Regulation of chondrocyte differentiation via a negative feedback loop formed together with parathyroid hormone-related protein (PTHrP), (2) promotion of chondrocyte proliferation, and (3) specification of bone-forming osteoblasts. Gli transcription factors mediate the major aspect of Hh signaling in this context. Gli3 has dominant roles in the growth plate chondrocytes, whereas Gli1, Gli2, and Gli3 collectively mediate biological functions of Hh signaling in osteoblast specification. Recent studies have also highlighted postnatal roles of the signaling in maintenance and repair of skeletal tissues.

Current Trends on Hemopoietic Stem Cells

Advances in single-cell technology and genetic mouse models have resulted in the identification of new types of hemopoietic stem cells (HSC), resulting in baffling observations, suggesting a reconsideration of the long-held notion that all hematopoietic cells in the adult are derived from HSCs. The existence of long-lived HSC-independent hematopoiesis has led to the conclusion that despite the single hierarchical differentiation route that generates functional blood types, other differentiation routes exist in-vivo. Heterogeneity in the HSC population and the evolving knowledge around HSC has translated to it's improved application as a therapeutic tool for various blood disorders. The reprogramming of non-hematopoietic somatic and mature blood cells to pluripotency with their subsequent differentiation into hematopoietic stem cells/progenitor cells and the introduction of new generation sequencing holds the potential for the resolution of ambiguities involved in HSC bone marrow transplantation. There is a change in the paradigm for HSC transplantation donor selection. Donor choice favors haploidentical HCT than cord blood. This review provides a general overview of the current events around hemopoietic stem cells, with emphasis on the rising trend of HSC transplantation, especially haploidentical stem cell transplantation.

Hedgehog Inhibitors Suppress Osteoclastogenesis in In Vitro Cultures, and Deletion of Smo in Macrophage/Osteoclast Lineage Prevents Age-Related Bone Loss

The functional role of the Hedgehog (Hh)-signaling pathway has been widely investigated in bone physiology/development. Previous studies have, however, focused primarily on Hh functions in bone formation, while its roles in bone resorption have not been fully elucidated. Here, we found that cyclopamine (smoothened (Smo) inhibitor), GANT-58 (GLI1 inhibitor), or GANT-61 (GLI1/2 inhibitor) significantly inhibited RANKL-induced osteoclast differentiation of bone marrow-derived macrophages. Although the inhibitory effects were exerted by cyclopamine or GANT-61 treatment during 0–48 h (early stage of osteoclast differentiation) or 48–96 h (late stage of osteoclast differentiation) after RANKL stimulation, GANT-58 suppressed osteoclast formation only during the early stage. These results suggest that the Smo-GLI1/2 axis mediates the whole process of osteoclastogenesis and that GLI1 activation is requisite only during early cellular events of osteoclastogenesis. Additionally, macrophage/osteoclast-specific deletion of Smo in mice was found to attenuate the aging phenotype characterized by trabecular low bone mass, suggesting that blockage of the Hh-signaling pathway in the osteoclast lineage plays a protective role against age-related bone loss. Our findings reveal a specific role of the Hh-signaling pathway in bone resorption and highlight that its inhibitors show potential as therapeutic agents that block osteoclast formation in the treatment of senile osteoporosis.