Stem Cells in Teeth and Craniofacial Bones

Stem cells are remarkable, and stem cell-based tissue engineering is an emerging field of biomedical science aiming to restore damaged tissue or organs. In dentistry and reconstructive facial surgery, it is of great interest to restore lost teeth or craniofacial bone defects using stem cell-mediated therapy. In the craniofacial region, various stem cell populations have been identified with regeneration potential. In this review, we provide an overview of the current knowledge concerning the various types of tooth- and craniofacial bone-related stem cells and discuss their in vivo identities and regulating mechanisms.

An Nfic-hedgehog signaling cascade regulates tooth root development

Coordination between the Hertwig's epithelial root sheath (HERS) and apical papilla (AP) is crucial for proper tooth root development. The hedgehog (Hh) signaling pathway and Nfic are both involved in tooth root development; however, their relationship has yet to be elucidated. Here, we establish a timecourse of mouse molar root development by histological staining of sections, and we demonstrate that Hh signaling is active before and during root development in the AP and HERS using Gli1 reporter mice. The proper pattern of Hh signaling activity in the AP is crucial for the proliferation of dental mesenchymal cells, because either inhibition with Hh inhibitors or constitutive activation of Hh signaling activity in transgenic mice leads to decreased proliferation in the AP and shorter roots. Moreover, Hh activity is elevated in Nfic(-/-) mice, a root defect model, whereas RNA sequencing and in situ hybridization show that the Hh attenuator Hhip is downregulated. ChIP and RNAscope analyses suggest that Nfic binds to the promoter region of Hhip. Treatment of Nfic(-/-) mice with Hh inhibitor partially restores cell proliferation, AP growth and root development. Taken together, our results demonstrate that an Nfic-Hhip-Hh signaling pathway is crucial for apical papilla growth and proper root formation. This discovery provides insight into the molecular mechanisms regulating tooth root development.

Histoplasmosis presenting with solitary pulmonary nodule: two cases mimicking pulmonary metastases

Pulmonary histoplasmosis is a granulomatous disease, whose diagnosis is not always easy, as it may simulate metastatic lesions due to similar radiographic findings. We herein report two cases of histoplasmosis with solitary pulmonary nodule in asymptomatic patients with histories of cancer surgeries, whose diagnoses were confirmed by postoperative pathological examinations. Doctors must pay attention to risk factors for immunosuppression such as the histories of chemotherapy, radiotherapy, or malignancy, which may increase chances of developing histoplasmosis. Limited surgical intervention is the treatment of choice for these localized lesions.

Low voltage and high ON/OFF ratio field-effect transistors based on CVD MoS2 and ultra high-k gate dielectric PZT

MoS2 and other atomic-level thick layered materials have been shown to have a high potential for outperforming Si transistors at the scaling limit. In this work, we demonstrate a MoS2 transistor with a low voltage and high ON/OFF ratio. A record small equivalent oxide thickness of ∼1.1 nm has been obtained by using ultra high-k gate dielectric Pb(Zr0.52Ti0.48)O3. The low threshold voltage (<0.5 V) is comparable to that of the liquid/gel gated MoS2 transistor. The small sub-threshold swing of 85.9 mV dec(-1), the high ON/OFF ratio of ∼10(8) and the negligible hysteresis ensure a high performance of the MoS2 transistor operating at 1 V. The extracted field-effect mobility of 1-10 cm(2) V(-1) s(-1) suggests a high crystalline quality of the CVD-grown MoS2 flakes. The combination of the two-dimensional layered semiconductor and the ultra high-k dielectric may enable the development of low-power electronic applications.

High-power passively mode-locked Nd:YVO(4) laser using SWCNT saturable absorber fabricated by dip coating method

Passive mode locked laser is typically achieved by the Semiconductor Saturable absorber Mirror, SESAM, saturable absorber, which is produced by expensive and complicated metal organic chemical vapor deposition method. Carbon based single wall carbon nanotube (SWCNT), saturable absorber, is a promising material which is capable to produce stable passive mode-locking in the high power laser cavity over a wide operational wavelength range. This study has successfully demonstrated the high power mode locking laser system operating at 1 micron by using SWCNT based absorbers fabricated by dip coating method. The proposed fabrication method is practical, simple and cost effective for fabricating SWCNT saturable absorber. The demonstrated high power Nd:YVO(4) mode-locked laser operating at 1064nm have maximum output power up to 2.7W,with the 167MHz repetition rate and 3.1 ps pulse duration, respectively. The calculated output pulse energy and peak power are 16.1nJ and 5.2kW, respectively.

Different requirements for Wnt signaling in tongue myogenic subpopulations

The tongue is a muscular organ that is essential in vertebrates for important functions, such as food intake and communication. Little is known about regulation of myogenic progenitors during tongue development when compared with the limb or trunk region. In this study, we investigated the relationship between different myogenic subpopulations and the function of canonical Wnt signaling in regulating these subpopulations. We found that Myf5- and MyoD-expressing myogenic subpopulations exist during embryonic tongue myogenesis. In the Myf5-expressing myogenic progenitors, there is a cell-autonomous requirement for canonical Wnt signaling for cell migration and differentiation. In contrast, the MyoD-expressing subpopulation does not require canonical Wnt signaling during tongue myogenesis. Taken together, our results demonstrate that canonical Wnt signaling differentially regulates the Myf5- and MyoD-expressing subpopulations during tongue myogenesis.

Autoantibodies response to MDM2 and p53 in the immunodiagnosis of esophageal squamous cell carcinoma

The human homologue of the mouse double minute 2 (MDM2) is known to be overexpressed in a variety of human malignancies. As one of E3 ubiquitin-protein ligases, MDM2 interacts with the tumour suppressor p53 by mediating ubiquitination and degradation of p53. Since abnormally expressed proteins can induce autoimmune response, to further examine whether sera from patients with esophageal squamous cell carcinoma (ESCC) exhibited immunoreactivity against MDM2 and p53, autoantibody responses to MDM2 and p53 were evaluated by enzyme-linked immunosorbent assay (ELISA) in sera from patients with ESCC and normal individuals. Positive results were also confirmed by Western blotting and indirect immunofluorescence assay. The results demonstrated that the positive rate of autoantibody against p53 and MDM2 in ESCC sera was 22.9% (36/157) and 14.0% (22/157), whereas this rate was 0% (0/85) and 1.2% (1/85), respectively, in normal individuals. Some of the sera with antibodies specific for MDM2 also contained antibodies against p53. And there was an increase of positive antibody reactions reaching a frequency of 35% (55/157) combination with MDM2 and p53. This was significantly higher than the frequency of antibodies in normal individuals (P < 0.01). Our preliminary results suggest that autoantibodies against MDM2 and p53 may be useful serum biomarkers in the immunodiagnosis of ESCC.

Mass transport mechanism of cu species at the metal/dielectric interfaces with a graphene barrier

The interface between the metal and dielectric is an indispensable part in various electronic devices. The migration of metallic species into the dielectric can adversely affect the reliability of the insulating dielectric and can also form a functional solid-state electrolyte device. In this work, we insert graphene between Cu and SiO2 as a barrier layer and investigate the mass transport mechanism of Cu species through the graphene barrier using density functional theory calculations, second-ion mass spectroscopy (SIMS), capacitance-voltage measurement, and cyclic voltammetry. Our theoretical calculations suggest that the major migration path for Cu species to penetrate through the multiple-layered graphene is the overlapped defects larger than 0.25 nm2. The depth-profile SIMS characterizations indicate that the "critical" thickness of the graphene barrier for completely blocking the Cu migration is 5 times smaller than that of the conventional TaN barrier. Capacitance-voltage and cyclic voltammetry measurement reveal that the electrochemical reactions at the Cu/SiO2 interface become a rate-limiting factor during the bias-temperature stressing process with the use of a graphene barrier. These studies provide a distinct roadmap for designing controllable mass transport in solid-state electrolyte devices with the use of a graphene barrier.

An ectopic hamartomatous thymoma compressing left jugular vein

Ectopic hamartomatous thymoma (EHT) is an extremely rare benign neoplasm. It is usually found at the root of the neck (frequently on the left) and does not usually impact adjacent tissues in clinically significant ways. While EHT manifests distinct pathological features, the lesion is either asymptomatic or may show nonspecific clinical features. We report one case of EHT which was assumed to be of low malignant potential since it severely compressed the inlet of left internal jugular vein as seen by computed tomography scan. To the best of our knowledge, this clinical finding of EHT is very rare. After the diagnosis and treatment of this patient, we believe that EHT or suspected EHT should be treated less invasively.

Improved multiphoton ultraviolet upconversion photoluminescence in ultrasmall core-shell nanocrystals

Near-infrared to ultraviolet multiphoton upconversion photoluminescence in ultrasmall Tm3+/Yb3+-codoped CaF2 nanocrystals (∼6.7  nm in size) was observed and further significantly enhanced by growing an active shell of NaYF4:Yb3+. Owing to the active shell, the lanthanide emitters inside the core are effectively prevented from the surface quenchers, and the excitation energy is absorbed more efficiently via the additional luminescence sensitizer Yb³⁺ embedded in the shell. The details of underlying physics were investigated and discussed. The results present a good ultrasmall luminescent material system for achieving efficient multiphoton upconversion, which shows great potential in versatile industrial and biological applications.

Two-dimensional material membranes: an emerging platform for controllable mass transport applications

Two-dimensional materials provide an ideal platform for studying the fundamental properties of atomic-level thickness systems, and are appropriate for lots of engineering applications in various fields. Although 2D materials are the thinnest membranes, they have been revealed to have high impermeability even to the smallest molecule. By the virtue of this high impermeability of the 2D materials in combination with their other unique properties, 2D materials open up a variety of applications that are impossible for conventional membranes. In this review, the latest applications based on high impermeability and selective permeation of these 2D material membranes are overviewed for different fields, including environmental control, chemical engineering, electronic devices, and biosensors. The working mechanism for each kind of application is described in detail. A summary and outlook is then provided on the challenges and new directions in this emerging research field.

A model for interprofessional health care: lessons learned from craniofacial teams

Seventy-six years ago, Herbert K. Cooper, DDS, DSc, LHD, FACD, created the first interprofessional health care team in response to the frequency of craniofacial anomalies and related speech and hearing deficits in Lancaster, Pa. His experiences and those from subsequent "medical-dental-nursing-pharmacy allied health professions" craniofacial teams inform and provide "best practices" for the future of interprofessional education. This paper revisits the genesis of craniofacial teams and highlights successes, challenges and cost benefits applicable today.

Controllable parabolic lensed liquid-core optical fiber by using electrostatic force

For typical optical fiber system, an external lens accessory set is required to adjust the optical path of output light, which however is limited by the fixed parameter of the lens accessory setup. Considering spherical aberration in the imaging process and its small focusable spot size, a complicated lens combination is required to compensate the aberration. This paper has demonstrated a unique method to fabricate liquid-core lensed fibers by filling water and NOA61 respectively into hollow Teflon AF fibers and silicate fiber, the radius of curvature of the liquid lens can be controlled by adjusting the applied voltage on the core liquid and even parabolic shape lens can be produced with enough applied voltage. The experiment has successfully demonstrated a variation of focal length from 0.628 mm to 0.111 mm responding to the change of applied voltage from 0V to 3.2KV (L = 2mm) for the Teflon AF fiber, as well as a variation of focal length from 0.274 mm to 0.08 mm responding to the change of applied voltage from 0V to 3KV (L = 2mm) for the silicate fiber. Further simulation shows that the focused spot size can be reduced to 2 µm by adjusting the refractive index and fiber geometry. Solid state parabolic lensed fiber can be produced after NOA61 is solidified by the UV curing.

Preparation and characterization of few-layer MoS2 nanosheets and their good nonlinear optical responses in the PMMA matrix

Due to the relatively weak van der Waals (VDW) force between interlayers, few-layer MoS2 nanosheets are prepared using a simple ultrasonic exfoliation method and incorporated into PMMA. The good nonlinear optical (NLO) property of the MoS2/PMMA composite for the nanosecond pulsed laser at both 532 and 1064 nm has been first reported. The size, thickness and atomic structure of MoS2 nanosheets have been characterized by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The interesting dependence of interlayer separation with respect to the layer number of MoS2 has been successfully quantified. The average interlayer separation of the MoS2 nanosheets increases and deviates much from the theoretical value with reducing the layer number. Such few-layer MoS2 nanosheets have been homogeneously incorporated into solid-state PMMA, which shows low optical limiting thresholds, 0.4 and 1.3 J cm(-2), and low limiting differential transmittance (TC), 2% and 3% for the nanosecond laser operating at 532 nm and 1064 nm, respectively. The results suggest that MoS2 nanosheet incorporated PMMA is a promising candidate of the solid NLO material for optical limiting applications.

Mapping of quantitative trait locus (QTLs) that contribute to germination and early seedling drought tolerance in the interspecific cross Setaria italica×Setaria viridis

Drought tolerance is an important breeding target for enhancing the yields of grain crop species in arid and semi-arid regions of the world. Two species of Setaria, domesticated foxtail millet (S. italica) and its wild ancestor green foxtail (S. viridis) are becoming widely adopted as models for functional genomics studies in the Panicoid grasses. In this study, the genomic regions controlling germination and early seedling drought tolerance in Setaria were identified using 190 F₇ lines derived from a cross between Yugu1, a S. italica cultivar developed in China, and a wild S. viridis genotype collected from Uzbekistan. Quantitative trait loci were identified which contribute to a number of traits including promptness index, radical root length, coleoptile length and lateral root number at germinating stage and seedling survival rate was characterized by the ability of desiccated seedlings to revive after rehydration. A genetic map with 128 SSR markers which spans 1293.9 cM with an average of 14 markers per linkage group of the 9 linkage groups was constructed. A total of eighteen QTLs were detected which included nine that explained over 10% of the phenotypic variance for a given trait. Both the wild green foxtail genotype and the foxtail millet cultivar contributed the favorite alleles for traits detected in this trial, indicating that wild Setaria viridis populations may serve as a reservoir for novel stress tolerance alleles which could be employed in foxtail millet breeding.

TGFβ regulates epithelial-mesenchymal interactions through WNT signaling activity to control muscle development in the soft palate

Clefting of the soft palate occurs as a congenital defect in humans and adversely affects the physiological function of the palate. However, the molecular and cellular mechanism of clefting of the soft palate remains unclear because few animal models exhibit an isolated cleft in the soft palate. Using three-dimensional microCT images and histological reconstruction, we found that loss of TGFβ signaling in the palatal epithelium led to soft palate muscle defects in Tgfbr2(fl/fl);K14-Cre mice. Specifically, muscle mass was decreased in the soft palates of Tgfbr2 mutant mice, following defects in cell proliferation and differentiation. Gene expression of Dickkopf (Dkk1 and Dkk4), negative regulators of WNT-β-catenin signaling, is upregulated in the soft palate of Tgfbr2(fl/fl);K14-Cre mice, and WNT-β-catenin signaling is disrupted in the palatal mesenchyme. Importantly, blocking the function of DKK1 and DKK4 rescued the cell proliferation and differentiation defects in the soft palate of Tgfbr2(fl/fl);K14-Cre mice. Thus, our findings indicate that loss of TGFβ signaling in epithelial cells compromises activation of WNT signaling and proper muscle development in the soft palate through tissue-tissue interactions, resulting in a cleft soft palate. This information has important implications for prevention and non-surgical correction of cleft soft palate.

Secretion of shh by a neurovascular bundle niche supports mesenchymal stem cell homeostasis in the adult mouse incisor

Mesenchymal stem cells (MSCs) are typically defined by their in vitro characteristics, and as a consequence the in vivo identity of MSCs and their niches are poorly understood. To address this issue, we used lineage tracing in a mouse incisor model and identified the neurovascular bundle (NVB) as an MSC niche. We found that NVB sensory nerves secrete Shh protein, which activates Gli1 expression in periarterial cells that contribute to all mesenchymal derivatives. These periarterial cells do not express classical MSC markers used to define MSCs in vitro. In contrast, NG2(+) pericytes represent an MSC subpopulation derived from Gli1+ cells; they express classical MSC markers and contribute little to homeostasis but are actively involved in injury repair. Likewise, incisor Gli1(+) cells, but not NG2(+) cells, exhibit typical MSC characteristics in vitro. Collectively, we demonstrate that MSCs originate from periarterial cells and are regulated by Shh secretion from an NVB.

Development of highly polymorphic simple sequence repeat markers using genome-wide microsatellite variant analysis in Foxtail millet [Setaria italica (L.) P. Beauv]

Background

Foxtail millet (Setaria italica (L.) Beauv.) is an important gramineous grain-food and forage crop. It is grown worldwide for human and livestock consumption. Its small genome and diploid nature have led to foxtail millet fast becoming a novel model for investigating plant architecture, drought tolerance and C₄ photosynthesis of grain and bioenergy crops. Therefore, cost-effective, reliable and highly polymorphic molecular markers covering the entire genome are required for diversity, mapping and functional genomics studies in this model species.

Result

A total of 5,020 highly repetitive microsatellite motifs were isolated from the released genome of the genotype 'Yugu1’ by sequence scanning. Based on sequence comparison between S. italica and S. viridis, a set of 788 SSR primer pairs were designed. Of these primers, 733 produced reproducible amplicons and were polymorphic among 28 Setaria genotypes selected from diverse geographical locations. The number of alleles detected by these SSR markers ranged from 2 to 16, with an average polymorphism information content of 0.67. The result obtained by neighbor-joining cluster analysis of 28 Setaria genotypes, based on Nei’s genetic distance of the SSR data, showed that these SSR markers are highly polymorphic and effective.

Conclusions

A large set of highly polymorphic SSR markers were successfully and efficiently developed based on genomic sequence comparison between different genotypes of the genus Setaria. The large number of new SSR markers and their placement on the physical map represent a valuable resource for studying diversity, constructing genetic maps, functional gene mapping, QTL exploration and molecular breeding in foxtail millet and its closely related species.

Effects of surface roughness of Ag thin films on surface-enhanced Raman spectroscopy of graphene: spatial nonlocality and physisorption strain

Metallic nanostructures are widely used for surface-enhanced Raman spectroscopy (SERS). Nanoscale surface corrugation significantly affects the localized plasmon response and the subsequent Raman intensity of the molecules in close proximity to the nanostructures. Experimentally, the surface roughness of metal films can be controlled by adjusting the deposition conditions, and the resulting localized near-field properties can be probed by measuring the Raman spectrum of the conformally coated monolayer graphene. The well-known Raman characteristics of graphene and its atomic-level 2D nature make it an ideal test-bed for SERS measurements on corrugated metal films. In this work, we experimentally and theoretically study the effects of surface roughness of Ag thin films on the SERS of graphene. We find that the nonlocality effect of the metal dielectric response has to be taken into account for more accurate prediction of the SERS enhancement at large surface roughness. Our results also reveal that the effect of physisorption strain should be included to understand the Raman peak shift and spectral broadening. These observations are fundamentally important for understanding the SERS from metallic nanostructures with sub-nanoscale corrugation.

Identification of candidate downstream targets of TGFβ signaling during palate development by genome-wide transcript profiling

Nonsyndromic orofacial clefts are common birth defects whose etiology is influenced by complex genetic and environmental factors and gene-environment interactions. Although these risk factors are not yet fully elucidated, it is known that alterations in transforming growth factor-beta (TGFβ) signaling can cause craniofacial abnormalities, including cleft palate, in mammals. To elucidate the downstream targets of TGFβ signaling in palatogenesis, we analyzed the gene expression profiles of Tgfbr2(fl/fl) ;Wnt1-Cre mouse embryos with cleft palate and other craniofacial deformities resulting from the targeted inactivation of the Tgfbr2 gene in their cranial neural crest (CNC) cells. Relative to controls, palatal tissues obtained from Tgfbr2(fl/fl) ;Wnt1-Cre mouse embryos at embryonic day 14.5 (E14.5) of gestation have a robust gene expression signature reflective of known defects in CNC-derived mesenchymal cell proliferation. Groups of differentially expressed genes (DEGs) were involved in diverse cellular processes and components associated with orofacial clefting, including the extracellular matrix, cholesterol metabolism, ciliogenesis, and multiple signaling pathways. A subset of the DEGs are known or suspected to be associated with an increased risk of orofacial clefting in humans and/or genetically engineered mice. Based on bioinformatics analyses, we highlight the functional relationships among differentially expressed transcriptional regulators of palatogenesis as well as transcriptional factors not previously associated with this process. We suggest that gene expression profiling studies of mice with TGFβ signaling defects provide a valuable approach for identifying candidate mechanisms by which this pathway controls cell fate during palatogenesis and its role in the etiology of human craniofacial abnormalities.

Molecular diversity and population structure of Chinese green foxtail [Setaria viridis (L.) Beauv.] revealed by microsatellite analysis

Green foxtail (Setaria viridis) is a new model plant for the genomic investigation of C4 photosynthesis biology. As the ancestor of foxtail millet (Setaria italica), an ancient cereal of great importance in arid regions of the world, green foxtail is crucial for the study of domestication and evolution of this ancient crop. In the present study, 288 green foxtail accessions, which were collected from all geographical regions of China, were analysed using 77 simple sequence repeats (SSRs) that cover the whole genome. A high degree of molecular diversity was detected in these accessions, with an average of 33.5 alleles per locus. Two clusters, which were inconsistent with the distribution of eco-geographical regions in China, were inferred from STRUCTURE, Neighbor-Joining, and principal component analysis, indicating a partially mixed distribution of Chinese green foxtails. The higher subpopulation diversity was from accessions mainly collected from North China. A low level of linkage disequilibrium was observed in the green foxtail genome. Furthermore, a combined analysis of green foxtail and foxtail millet landraces was conducted, and the origin and domestication of foxtail millet was inferred in North China.

Modulation of lipid metabolic defects rescues cleft palate in Tgfbr2 mutant mice

Mutations in transforming growth factor beta (TGFβ) receptor type II (TGFBR2) cause Loeys-Dietz syndrome, characterized by craniofacial and cardiovascular abnormalities. Mice with a deletion of Tgfbr2 in cranial neural crest cells (Tgfbr2(fl/fl);Wnt1-Cre mice) develop cleft palate as the result of abnormal TGFβ signaling activation. However, little is known about metabolic processes downstream of TGFβ signaling during palatogenesis. Here, we show that Tgfbr2 mutant palatal mesenchymal cells spontaneously accumulate lipid droplets, resulting from reduced lipolysis activity. Tgfbr2 mutant palatal mesenchymal cells failed to respond to the cell proliferation stimulator sonic hedgehog, derived from the palatal epithelium. Treatment with p38 mitogen-activated protein kinase (MAPK) inhibitor or telmisartan, a modulator of p38 MAPK activation and lipid metabolism, blocked abnormal TGFβ-mediated p38 MAPK activation, restoring lipid metabolism and cell proliferation activity both in vitro and in vivo. Our results highlight the influence of alternative TGFβ signaling on lipid metabolic activities, as well as how lipid metabolic defects can affect cell proliferation and adversely impact palatogenesis. This discovery has broader implications for the understanding of metabolic defects and potential prevention of congenital birth defects.

Noncanonical transforming growth factor β (TGFβ) signaling in cranial neural crest cells causes tongue muscle developmental defects

Microglossia is a congenital birth defect in humans and adversely impacts quality of life. In vertebrates, tongue muscle derives from the cranial mesoderm, whereas tendons and connective tissues in the craniofacial region originate from cranial neural crest (CNC) cells. Loss of transforming growth factor β (TGFβ) type II receptor in CNC cells in mice (Tgfbr2(fl/fl);Wnt1-Cre) causes microglossia due to a failure of cell-cell communication between cranial mesoderm and CNC cells during tongue development. However, it is still unclear how TGFβ signaling in CNC cells regulates the fate of mesoderm-derived myoblasts during tongue development. Here we show that activation of the cytoplasmic and nuclear tyrosine kinase 1 (ABL1) cascade in Tgfbr2(fl/fl);Wnt1-Cre mice results in a failure of CNC-derived cell differentiation followed by a disruption of TGFβ-mediated induction of growth factors and reduction of myogenic cell proliferation and differentiation activities. Among the affected growth factors, the addition of fibroblast growth factor 4 (FGF4) and neutralizing antibody for follistatin (FST; an antagonist of bone morphogenetic protein (BMP)) could most efficiently restore cell proliferation, differentiation, and organization of muscle cells in the tongue of Tgfbr2(fl/fl);Wnt1-Cre mice. Thus, our data indicate that CNC-derived fibroblasts regulate the fate of mesoderm-derived myoblasts through TGFβ-mediated regulation of FGF and BMP signaling during tongue development.

Gingivae contain neural-crest- and mesoderm-derived mesenchymal stem cells

Gingivae represent a unique soft tissue that serves as a biological barrier to cover the oral cavity side of the maxilla and mandible. Recently, the gingivae were identified as containing mesenchymal stem cells (GMSCs). However, it is unknown whether the GMSCs are derived from cranial neural crest cells (CNCC) or the mesoderm. In this study, we show that around 90% of GMSCs are derived from CNCC and 10% from the mesoderm. In comparison with mesoderm MSCs (M-GMSCs), CNCC-derived GMSCs (N-GMSCs) show an elevated capacity to differentiate into neural cells and chondrocytes and induce activated T-cell apoptosis in vitro. When transplanted into mice with dextran sulfate sodium (DSS)-induced colitis, N-GMSCs showed superior effects in ameliorating inflammatory-related disease phenotype in comparison with the M-GMSC treatment group. Mechanistically, the increased immunomodulatory effect of N-GMSCs is associated with up-regulated expression of FAS ligand (FASL), a transmembrane protein that plays an important role in MSC-based immunomodulation. In summary, our study indicates that the gingivae contain both neural-crest- and mesoderm-derived MSCs with distinctive stem cell properties.

Smad2 and myocardin-related transcription factor B cooperatively regulate vascular smooth muscle differentiation from neural crest cells

RATIONALE

Vascular smooth muscle cell (VSMC) differentiation from neural crest cells (NCCs) is critical for cardiovascular development, but the mechanisms remain largely unknown.

OBJECTIVE

Transforming growth factor-β (TGF-β) function in VSMC differentiation from NCCs is controversial. Therefore, we determined the role and mechanism of a TGF-β downstream signaling intermediate Smad2 in NCC differentiation to VSMCs.

METHODS AND RESULTS

By using Cre/loxP system, we generated a NCC tissue-specific Smad2 knockout mouse model and found that Smad2 deletion resulted in defective NCC differentiation to VSMCs in aortic arch arteries during embryonic development and caused vessel wall abnormality in adult carotid arteries where the VSMCs are derived from NCCs. The abnormalities included 1 layer of VSMCs missing in the media of the arteries with distorted and thinner elastic lamina, leading to a thinner vessel wall compared with wild-type vessel. Mechanistically, Smad2 interacted with myocardin-related transcription factor B (MRTFB) to regulate VSMC marker gene expression. Smad2 was required for TGF-β-induced MRTFB nuclear translocation, whereas MRTFB enhanced Smad2 binding to VSMC marker promoter. Furthermore, we found that Smad2, but not Smad3, was a progenitor-specific transcription factor mediating TGF-β-induced VSMC differentiation from NCCs. Smad2 also seemed to be involved in determining the physiological differences between NCC-derived and mesoderm-derived VSMCs.

CONCLUSIONS

Smad2 is an important factor in regulating progenitor-specific VSMC development and physiological differences between NCC-derived and mesoderm-derived VSMCs.

Regulation of the epithelial adhesion molecule CEACAM1 is important for palate formation

Cleft palate results from a mixture of genetic and environmental factors and occurs when the bilateral palatal shelves fail to fuse. The objective of this study was to search for new genes involved in mouse palate formation. Gene expression of murine embryonic palatal tissue was analyzed at various developmental stages before, during, and after palate fusion using GeneChip® microarrays. Ceacam1 was one of the highly up-regulated genes during palate formation, and this was confirmed by quantitative real-time PCR. Immunohistochemical staining showed that CEACAM1 was present in prefusion palatal epithelium and was degraded during fusion. To investigate the developmental role of CEACAM1, function-blocking antibody was added to embryonic mouse palate in organ culture. Palatal fusion was inhibited by this function-blocking antibody. To investigate the subsequent developmental role of CEACAM1, we characterized Ceacam1-deficient (Ceacam1^−/−) mice. Epithelial cells persisted abnormally at the midline of the embryonic palate even on day E16.0, and palatal fusion was delayed in Ceacam1^−/− mice. TGFβ3 expression, apoptosis, and cell proliferation in palatal epithelium were not affected in the palate of Ceacam1^−/−mice. However, CEACAM1 expression was retained in the remaining MEE of TGFβ-deficient mice. These results suggest that CEACAM1 has roles in the initiation of palatal fusion via epithelial cell adhesion.

Giant fibrous tumours of the pleura with mucus secretion

Solitary fibrous tumors of the pleura (SFTP) are rare. We report a case of giant SFTP treated by surgical resection. We found that many soft tumors were separated by fibrous cords and creamy white mucus in our case. Among them, one great mass measured 23 cm × 18 cm × 10 cm. These tumors weighed 3750 g. The patient had no postoperative complications and received a good prognosis.

Mice with Tak1 deficiency in neural crest lineage exhibit cleft palate associated with abnormal tongue development

Cleft palate represents one of the most common congenital birth defects in humans. TGFβ signaling, which is mediated by Smad-dependent and Smad-independent pathways, plays a crucial role in regulating craniofacial development and patterning, particularly in palate development. However, it remains largely unknown whether the Smad-independent pathway contributes to TGFβ signaling function during palatogenesis. In this study, we investigated the function of TGFβ activated kinase 1 (Tak1), a key regulator of Smad-independent TGFβ signaling in palate development. We show that Tak1 protein is expressed in both the epithelium and mesenchyme of the developing palatal shelves. Whereas deletion of Tak1 in the palatal epithelium or mesenchyme did not give rise to a cleft palate defect, inactivation of Tak1 in the neural crest lineage using the Wnt1-Cre transgenic allele resulted in failed palate elevation and subsequently the cleft palate formation. The failure in palate elevation in Wnt1-Cre;Tak1(F/F) mice results from a malformed tongue and micrognathia, resembling human Pierre Robin sequence cleft of the secondary palate. We found that the abnormal tongue development is associated with Fgf10 overexpression in the neural crest-derived tongue tissue. The failed palate elevation and cleft palate were recapitulated in an Fgf10-overexpressing mouse model. The repressive effect of the Tak1-mediated noncanonical TGFβ signaling on Fgf10 expression was further confirmed by inhibition of p38, a downstream kinase of Tak1, in the primary cell culture of developing tongue. Tak1 thus functions to regulate tongue development by controlling Fgf10 expression and could represent a candidate gene for mutation in human PRS clefting.

Radiation-induced non-targeted response in vivo: role of the TGFβ-TGFBR1-COX-2 signalling pathway

Background:

Previous studies from our group and others have shown that cyclooxygenase-2 (COX-2) has an essential role in radiation-induced non-targeted responses and genomic instability in vivo. However, the signalling pathways involved in such effects remain unclear.

Methods:

A 1 cm² area (1 cm × 1 cm) in the lower abdominal region of gpt delta transgenic mice was irradiated with 5 Gy of 300 keV X-rays. Nimesulide, a selective COX-2 inhibitor, was given to mice for five consecutive days before irradiation. Changes in transforming growth factor-beta (TGF-β) and TGF-β receptor type-1 (TGFBR1) mediated signalling pathways, in the out of radiation field lung and liver tissues were examined.

Results:

While the plasma level of cytokines remained unchanged, the expression of TGF-β and its receptors was elevated in non-targeted lung tissues after partial body irradiation. In contrast to the predominant expression of TGF-β in stromal and alveolar cells, but not in bronchial epithelial cells, TGF-β receptors, especially TGFBR1 were significantly elevated in non-targeted bronchial epithelial cells, which is consistent with the induction of COX-2. The different expression levels of TGFBR1 between liver and lung resulted in a tissue specific induction of COX-2 in these two non-targeted tissues. Multiple TGF-β induced signalling pathways were activated in the non-targeted lung tissues.

Conclusion:

The TGFβ-TGFBR1-COX-2 Signalling Pathway has a critical role in radiation-induced non-targeted response in vivo.

Smad4-Irf6 genetic interaction and TGFβ-mediated IRF6 signaling cascade are crucial for palatal fusion in mice

Cleft palate is one of the most common human birth defects and is associated with multiple genetic and environmental risk factors. Although mutations in the genes encoding transforming growth factor beta (TGFβ) signaling molecules and interferon regulatory factor 6 (Irf6) have been identified as genetic risk factors for cleft palate, little is known about the relationship between TGFβ signaling and IRF6 activity during palate formation. Here, we show that TGFβ signaling regulates expression of Irf6 and the fate of the medial edge epithelium (MEE) during palatal fusion in mice. Haploinsufficiency of Irf6 in mice with basal epithelial-specific deletion of the TGFβ signaling mediator Smad4 (Smad4(fl/fl);K14-Cre;Irf6(+/R84C)) results in compromised p21 expression and MEE persistence, similar to observations in Tgfbr2(fl/fl);K14-Cre mice, although the secondary palate of Irf6(+/R84C) and Smad4(fl/fl);K14-Cre mice form normally. Furthermore, Smad4(fl/fl);K14-Cre;Irf6(+/R84C) mice show extra digits that are consistent with abnormal toe and nail phenotypes in individuals with Van der Woude and popliteal pterygium syndromes, suggesting that the TGFβ/SMAD4/IRF6 signaling cascade might be a well-conserved mechanism in regulating multiple organogenesis. Strikingly, overexpression of Irf6 rescued p21 expression and MEE degeneration in Tgfbr2(fl/fl);K14-Cre mice. Thus, IRF6 and SMAD4 synergistically regulate the fate of the MEE, and TGFβ-mediated Irf6 activity is responsible for MEE degeneration during palatal fusion in mice.

Molecular regulatory mechanism of tooth root development

The root is crucial for the physiological function of the tooth, and a healthy root allows an artificial crown to function as required clinically. Tooth crown development has been studied intensively during the last few decades, but root development remains not well understood. Here we review the root development processes, including cell fate determination, induction of odontoblast and cementoblast differentiation, interaction of root epithelium and mesenchyme, and other molecular mechanisms. This review summarizes our current understanding of the signaling cascades and mechanisms involved in root development. It also sets the stage for de novo tooth regeneration.

Roles of BMP signaling pathway in lip and palate development

Cleft lip with or without cleft palate (CLP) and cleft palate only (CP) are severe disruptions affecting orofacial structures. Patients with orofacial clefts require complex interdisciplinary care, which includes nursing, plastic surgery, maxillofacial surgery, otolaryngology, speech therapy, audiology, psychological and genetic counseling, orthodontics and dental treatment, among others. Overall, treatment of clefts of the lip and palate entails a significant economic burden for families and society. Therefore, prevention is the ultimate objective and this will be facilitated by a complete understanding of the etiology of this condition. Here we review the current concepts regarding the genetic and environmental factors contributing to orofacial clefts and emphasize on the roles of BMP signaling pathway components in the normal and aberrant development of the lip and palate.

A collaborative approach to advance student research at the University of Southern California

The continued advancement of oral health and science relies upon the cultivation of a student's interest in research. The Student Research Group at the Ostrow School of Dentistry of the University of Southern California is working to increase student involvement in research and develop future academic leaders. This study aims to, through student surveys, quantitatively evaluate students' involvement in research, students' interest in participating in research and to identify specific barriers students feel challenge their ability to participate in research.

A TGFβ-Smad4-Fgf6 signaling cascade controls myogenic differentiation and myoblast fusion during tongue development

The tongue is a muscular organ and plays a crucial role in speech, deglutition and taste. Despite the important physiological functions of the tongue, little is known about the regulatory mechanisms of tongue muscle development. TGFβ family members play important roles in regulating myogenesis, but the functional significance of Smad-dependent TGFβ signaling in regulating tongue skeletal muscle development remains unclear. In this study, we have investigated Smad4-mediated TGFβ signaling in the development of occipital somite-derived myogenic progenitors during tongue morphogenesis through tissue-specific inactivation of Smad4 (using Myf5-Cre;Smad4(flox/flox) mice). During the initiation of tongue development, cranial neural crest (CNC) cells occupy the tongue buds before myogenic progenitors migrate into the tongue primordium, suggesting that CNC cells play an instructive role in guiding tongue muscle development. Moreover, ablation of Smad4 results in defects in myogenic terminal differentiation and myoblast fusion. Despite compromised muscle differentiation, tendon formation appears unaffected in the tongue of Myf5-Cre;Smad4(flox/flox) mice, suggesting that the differentiation and maintenance of CNC-derived tendon cells are independent of Smad4-mediated signaling in myogenic cells in the tongue. Furthermore, loss of Smad4 results in a significant reduction in expression of several members of the FGF family, including Fgf6 and Fgfr4. Exogenous Fgf6 partially rescues the tongue myoblast fusion defect of Myf5-Cre;Smad4(flox/flox) mice. Taken together, our study demonstrates that a TGFβ-Smad4-Fgf6 signaling cascade plays a crucial role in myogenic cell fate determination and lineage progression during tongue myogenesis.

Modulation of noncanonical TGF-β signaling prevents cleft palate in Tgfbr2 mutant mice

Patients with mutations in either TGF-β receptor type I (TGFBR1) or TGF-β receptor type II (TGFBR2), such as those with Loeys-Dietz syndrome, have craniofacial defects and signs of elevated TGF-β signaling. Similarly, mutations in TGF-β receptor gene family members cause craniofacial deformities, such as cleft palate, in mice. However, it is unknown whether TGF-β ligands are able to elicit signals in Tgfbr2 mutant mice. Here, we show that loss of Tgfbr2 in mouse cranial neural crest cells results in elevated expression of TGF-β2 and TGF-β receptor type III (TβRIII); activation of a TβRI/TβRIII-mediated, SMAD-independent, TRAF6/TAK1/p38 signaling pathway; and defective cell proliferation in the palatal mesenchyme. Strikingly, Tgfb2, Tgfbr1 (also known as Alk5), or Tak1 haploinsufficiency disrupted TβRI/TβRIII-mediated signaling and rescued craniofacial deformities in Tgfbr2 mutant mice, indicating that activation of this noncanonical TGF-β signaling pathway was responsible for craniofacial malformations in Tgfbr2 mutant mice. Thus, modulation of TGF-β signaling may be beneficial for the prevention of congenital craniofacial birth defects.

Fibroblast growth factor 9 (FGF9)-pituitary homeobox 2 (PITX2) pathway mediates transforming growth factor β (TGFβ) signaling to regulate cell proliferation in palatal mesenchyme during mouse palatogenesis

Cleft palate represents one of the most common congenital birth defects. Transforming growth factor β (TGFβ) signaling plays crucial functions in regulating craniofacial development, and loss of TGFβ receptor type II in cranial neural crest cells leads to craniofacial malformations, including cleft palate in mice (Tgfbr2(fl/fl);Wnt1-Cre mice). Here we have identified candidate target genes of TGFβ signaling during palatal formation. These target genes were selected based on combining results from gene expression profiles of embryonic day 14.5 palates from Tgfbr2(fl/fl);Wnt1-Cre mice and previously identified cleft palate phenotypes in genetically engineered mouse models. We found that fibroblast growth factor 9 (Fgf9) and transcription factor pituitary homeobox 2 (Pitx2) expressions are significantly down-regulated in the palate of Tgfbr2(fl/fl);Wnt1-Cre mice, and Fgf9 and Pitx2 loss of function mutations result in cleft palate in mice. Pitx2 expression is down-regulated by siRNA knockdown of Fgf9, suggesting that Fgf9 is upstream of Pitx2. We detected decreased expression of both cyclins D1 and D3 in the palates of Tgfbr2(fl/fl);Wnt1-Cre mice, consistent with the defect in cell proliferation. Significantly, exogenous FGF9 restores expression of cyclins D1 and D3 in a Pitx2-dependent manner and rescues the cell proliferation defect in the palatal mesenchyme of Tgfbr2(fl/fl);Wnt1-Cre mice. Our study indicates that a TGFβ-FGF9-PITX2 signaling cascade regulates cranial neural crest cell proliferation during palate formation.

Molecular and cellular regulatory mechanisms of tongue myogenesis

The tongue exerts crucial functions in our daily life. However, we know very little about the regulatory mechanisms of mammalian tongue development. In this review, we summarize recent findings of the molecular and cellular mechanisms that control tissue-tissue interactions during tongue morphogenesis. Specifically, cranial neural crest cells (CNCC) lead the initiation of tongue bud formation and contribute to the interstitial connective tissue, which ultimately compartmentalizes tongue muscles and serves as their attachments. Occipital somite-derived cells migrate into the tongue primordium and give rise to muscle cells in the tongue. The intimate relationship between CNCC- and mesoderm-derived cells, as well as growth and transcription factors that have been shown to be crucial for tongue myogenesis, clearly indicate that tissue-tissue interactions play an important role in regulating tongue morphogenesis.

Tgf-beta-mediated FasL-Fas-Caspase pathway is crucial during palatogenesis

Programmed cell death, or apoptosis, is one of the fates of the medial edge epithelium (MEE) during palatal fusion. Transforming growth factor β (Tgf-β) signaling (such as Tgf-β3) is required for the disappearance of the MEE, but the relationship between Tgf-β3 and apoptosis remains unclear. Here we show that the Fas ligand (FasL)-Fas-Caspase extrinsic apoptosis pathway functions during palatal fusion in wild-type mice, but is not detectable in mice lacking Tgf-β3 (Tgf-β3 (-/-) ) or Tgfβr2 in the MEE (K14-Cre;Tgfbr2 (fl/fl)). Inhibition of the FasL-Fas system results in persistence of the midline epithelial seam (MES) and inhibition of caspase activity during palatal organ culture. Moreover, ectopic FasL protein induces apoptosis in MES of K14-Cre;Tgfbr2 (fl/fl) mice. Thus, we conclude that the FasL-Fas-caspase extrinsic apoptosis pathway is regulated by the Tgf-β3 signaling cascade and is essential for palatal fusion during craniofacial development.

Molecular regulatory mechanism of root development

TGF-beta signaling is known to function during tooth formation. The authors' study investigated the role of TGF-beta signaling during tooth root development and determined how the common mediator for TGF-beta signaling, Smad4, affected root formation in mice. Smod4 was specifically inactivated in all epidermal-derived tissues by using a two-component genetic system. The authors' findings show that when Smad4 expression is eliminated in the dental epithelium, there is lack of root formation and severe crown defects.