Increased miR-200c levels disrupt palatal fusion by affecting apoptosis, cell proliferation, and cell migration.

The mammalian palate separates the oral and nasal cavities, facilitating proper feeding, respiration, and speech. Palatal shelves, composed of neural crest-derived mesenchyme and surrounding epithelium, are a pair of maxillary prominences contributing to this structure. Palatogenesis reaches completion upon the fusion of the midline epithelial seam (MES) following contact between medial edge epithelium (MEE) cells in the palatal shelves. This process entails numerous cellular and molecular occurrences, including apoptosis, cell proliferation, cell migration, and epithelial-mesenchymal transition (EMT). MicroRNAs (miRs) are small, endogenous, non-coding RNAs derived from double-stranded hairpin precursors that regulate gene expression by binding to target mRNA sequences. Although miR-200c is a positive regulator of E-cadherin, its role in palatogenesis remains unclear. This study aims to explore the role of miR-200c in palate development. Before contact with palatal shelves, mir-200c was expressed in the MEE along with E-cadherin. After palatal shelf contact, miR-200c was present in the palatal epithelial lining and epithelial islands surrounding the fusion region but absent in the mesenchyme. The function of miR-200c was investigated by utilizing a lentiviral vector to facilitate overexpression. Ectopic expression of miR-200c resulted in E-cadherin upregulation, impaired dissolution of the MES, and reduced cell migration for palatal fusion. The findings imply that miR-200c is essential in palatal fusion as it governs E-cadherin expression, cell death, and cell migration, acting as a non-coding RNA. This study may contribute to clarifying the underlying molecular mechanisms in palate formation and provides insights into potential gene therapies for cleft palate.

Distinct roles of stereociliary links in the nonlinear sound processing and noise resistance of cochlear outer hair cells.

Outer hair cells (OHCs) play an essential role in hearing by acting as a nonlinear amplifier which helps the cochlea detect sounds with high sensitivity and accuracy. This nonlinear sound processing generates distortion products, which can be measured as distortion-product otoacoustic emissions (DPOAEs). The OHC stereocilia that respond to sound vibrations are connected by three kinds of extracellular links: tip links that connect the taller stereocilia to shorter ones and convey force to the mechanoelectrical transduction channels, tectorial membrane-attachment crowns (TM-ACs) that connect the tallest stereocilia to one another and to the overlying TM, and horizontal top connectors (HTCs) that link adjacent stereocilia. While the tip links have been extensively studied, the roles that the other two types of links play in hearing are much less clear, largely because of a lack of suitable animal models. Here, while analyzing genetic combinations of tubby mice, we encountered models missing both HTCs and TM-ACs or HTCs alone. We found that the tubby mutation causes loss of both HTCs and TM-ACs due to a mislocalization of stereocilin, which results in OHC dysfunction leading to severe hearing loss. Intriguingly, the addition of the modifier allele modifier of tubby hearing 1 in tubby mice selectively rescues the TM-ACs but not the HTCs. Hearing is significantly rescued in these mice with robust DPOAE production, indicating an essential role of the TM-ACs but not the HTCs in normal OHC function. In contrast, the HTCs are required for the resistance of hearing to damage caused by noise stress.

Supraclavicular cephalic vein draining into the internal jugular vein via the external jugular vein.

PURPOSE: The aim of this study is to report rare anatomical variations of the cephalic vein (CV) in a 77-year-old Korean male cadaver. CASE REPORT: On the right upper arm, the CV located lateral to the deltopectoral groove passed anterior to the clavicle at the lateral one-fourth of the clavicle without anastomosis to the axillary vein. It was connected to the transverse cervical and suprascapular veins by two communicating branches in the middle of its course at the neck, and opened into the external jugular vein at its junction with the internal jugular veins. The suprascapular and anterior jugular veins were flowed into the subclavian vein at the jugulo-subclavian venous confluence, and were connected by a short communicating branch. CONCLUSION: Detailed knowledge of the variations in the CV is expected to be helpful in decreasing unpredicted injuries and possible postoperative complications when invasive venous access is performed through the CV.

Impact of miR-192 and miR-194 on cyst enlargement through EMT in autosomal dominant polycystic kidney disease.

Altered miRNA (miR) expression occurs in various diseases. However, the therapeutic effect of miRNAs in autosomal dominant polycystic kidney disease (ADPKD) is unclear. Genome-wide analyses of miRNA expression and DNA methylation status were conducted to identify crucial miRNAs in end-stage ADPKD. miR-192 and -194 levels were down-regulated with hypermethylation at these loci, mainly in the intermediate and late stages, not in the early stage, of cystogenesis, suggesting their potential impact on cyst expansion. Cyst expansion has been strongly associated with endothelial-mesenchymal transition (EMT). Zinc finger E-box-binding homeobox-2 and cadherin-2, which are involved in EMT, were directly regulated by miR-192 and -194. The therapeutic effect of miR-192 and -194 in vivo and in vitro were assessed. Restoring these miRs by injection of precursors influenced the reduced size of cysts in Pkd1 conditional knockout mice. miR-192 and -194 may act as potential therapeutic targets to control the expansion and progression of cysts in patients with ADPKD.-Kim, D. Y., Woo, Y. M., Lee, S., Oh, S., Shin, Y., Shin, J.-O., Park, E. Y., Ko, J. Y., Lee, E. J., Bok, J., Yoo, K. H., Park, J. H. Impact of miR-192 and miR-194 on cyst enlargement through EMT in autosomal dominant polycystic kidney disease.

CTCF deficiency causes expansion of the sensory domain in the mouse cochlea.

The cochlea in the mammalian inner ear is a sensitive and sharply organized sound-detecting structure. The proper specification of neurosensory-competent domain in the otic epithelium is required for the formation of mature neuronal and sensory domains. Genetic studies have provided many insights into inner ear development, but there have been few epigenetic studies of inner ear development. CTCF is an epigenetic factor that plays a pivotal role in the organization of global chromatin conformation. To determine the role of CTCF in the otic sensory formation, we made a conditional knockout of Ctcf in the developing otic epithelium by crossing Ctcffl/fl mice with Pax2-Cre mice. Ctcf deficiency resulted in extra rows of auditory hair cells in the shortened cochlea on mouse embryonic day 14.5 (E14.5) and E17.5. The massive and ectopic expression of sensory specifiers such as Jag1 and Sox2 indicated that the sensory domain was expanded in the Ctcf-deficient cochlea. Other regulators of the sensory domain such as Bmp4, Gata3, and Fgf10 were not affected. These results suggest that CTCF plays a role in the regulation of the sensory domain in mammalian cochlear development.

Inhibition of the Zeb family prevents murine palatogenesis through regulation of apoptosis and the cell cycle.

Mammalian palate separates the oral and nasal cavities for normal feeding, breathing and speech. The palatal shelves are a pair of maxillary prominences that consist of the neural crest-derived mesenchyme and surrounding epithelium. Palatogenesis is completed by the fusion of the midline epithelial seam (MES) after the medial edge epithelium (MEE) cells make contact between the palatal shelves. Various cellular and molecular events, such as apoptosis, cell proliferation, cell migration, and epithelial-mesenchymal transition (EMT), are involved in palatogenesis. The Zeb family of transcription factors is an essential player during normal embryonic development. The distinct role of the Zeb family has not been thoroughly elucidated to date. In mouse palate, the Zeb family factors are expressed in the palatal mesenchyme until MEE contact. Interestingly, the expression of the Zeb family has also been observed in MES, which is already fused with the mesenchymal region. The regulatory roles of the Zeb family in palatogenesis have not been elucidated to date. The purpose of this study is to determine the Zeb family effects on the cellular events. To investigate the functions of the Zeb family, siRNA targeting Zeb family was used to treat in vitro organ culture for temporary inhibition of the Zeb family during palatogenesis. In the cultured palate containing siRNA, MES was clearly observed, and E-cadherin, an epithelial marker, was still expressed. Inhibition of the Zeb family results in the suppression of apoptosis, increased cell proliferation, and defective cell migration in the developing palate. Our data suggest that the Zeb family plays multiple roles in the stimulation and inhibition of apoptosis and cell proliferation and efficient mesenchymal cell migration during palatogenesis.

CTCF is required for maintenance of auditory hair cells and hearing function in the mouse cochlea.

Auditory hair cells play an essential role in hearing. These cells convert sound waves, mechanical stimuli, into electrical signals that are conveyed to the brain via spiral ganglion neurons. The hair cells are located in the organ of Corti within the cochlea. They assemble in a special arrangement with three rows of outer hair cells and one row of inner hair cells. The proper differentiation and preservation of auditory hair cells are essential for acquiring and maintaining hearing function, respectively. Many genetic regulatory mechanisms underlying hair-cell differentiation and maintenance have been elucidated to date. However, the role of epigenetic regulation in hair-cell differentiation and maintenance has not been definitively demonstrated. CTCF is an essential epigenetic component that plays a primary role in the organization of global chromatin architecture. To determine the role of CTCF in mammalian hair cells, we specifically deleted Ctcf in developing hair cells by crossing Ctcffl/fl mice with Gfi1Cre/+ mice. Gfi1Cre; Ctcffl/fl mice did not exhibit obvious developmental defects in hair cells until postnatal day 8. However, at 3 weeks, the Ctcf deficiency caused intermittent degeneration of the stereociliary bundles of outer hair cells, resulting in profound hearing impairment. At 5 weeks, most hair cells were degenerated in Gfi1Cre; Ctcffl/fl mice, and defects in other structures of the organ of Corti, such as the tunnel of Corti and Nuel's space, became apparent. These results suggest that CTCF plays an essential role in maintaining hair cells and hearing function in mammalian cochlea.

Conserved role of Sonic Hedgehog in tonotopic organization of the avian basilar papilla and mammalian cochlea.

Sound frequency discrimination begins at the organ of Corti in mammals and the basilar papilla in birds. Both of these hearing organs are tonotopically organized such that sensory hair cells at the basal (proximal) end respond to high frequency sound, whereas their counterparts at the apex (distal) respond to low frequencies. Sonic hedgehog (Shh) secreted by the developing notochord and floor plate is required for cochlear formation in both species. In mice, the apical region of the developing cochlea, closer to the ventral midline source of Shh, requires higher levels of Shh signaling than the basal cochlea farther away from the midline. Here, gain-of-function experiments using Shh-soaked beads in ovo or a mouse model expressing constitutively activated Smoothened (transducer of Shh signaling) show up-regulation of apical genes in the basal cochlea, even though these regionally expressed genes are not necessarily conserved between the two species. In chicken, these altered gene expression patterns precede morphological and physiological changes in sensory hair cells that are typically associated with tonotopy such as the total number of stereocilia per hair cell and gene expression of an inward rectifier potassium channel, IRK1, which is a bona fide feature of apical hair cells in the basilar papilla. Furthermore, our results suggest that this conserved role of Shh in establishing cochlear tonotopy is initiated early in development by Shh emanating from the notochord and floor plate.

Spatiotemporal expression patterns of clusterin in the mouse inner ear.

Clusterin (CLU) is an extracellular chaperone protein that is implicated in diverse physiological and pathophysiological cellular processes. CLU expression is upregulated in response to cellular stress and under certain conditions, such as neurodegenerative disease and cancer. CLU primarily functions as a chaperone that exerts cytoprotective effects by removing cellular debris and misfolded proteins and also acts as a signaling molecule that regulates pro-survival pathways. Deafness is caused by genetic factors and various extrinsic insults, including ototoxic drugs, exposure to loud sounds and aging. Considering its cytoprotectivity, CLU may also mediate cellular defense mechanisms against hearing loss due to cellular stresses. To understand the function of CLU in the inner ear, we analyze CLU expression patterns in the mouse inner ear during development and in the adult stage. Results of quantitative real-time polymerase chain reaction analysis showed that Clu mRNA levels in the inner ear were increased during embryogenesis and were constantly expressed in the adult. Detailed spatial expression patterns of Clu both in the mRNA and protein levels were analyzed throughout various developmental stages via in situ hybridization and immunofluorescence staining. Clu expression was found in specific domains of developing inner ear starting from the otocyst stage, mainly adjacent to the prosensory domain of the cochlear epithelium. In the mature inner ear, Clu expression was observed in Deiter's cells and pillar cells of the organ of Corti, outer sulcus and in basal cells of the stria vascularis in the cochlea. These specific spatiotemporal expression patterns suggest the possible roles of CLU in inner ear development and in maintaining proper hearing function.

Intestinal cell kinase, a protein associated with endocrine-cerebro-osteodysplasia syndrome, is a key regulator of cilia length and Hedgehog signaling.

Endocrine-cerebro-osteodysplasia (ECO) syndrome is a recessive genetic disorder associated with multiple congenital defects in endocrine, cerebral, and skeletal systems that is caused by a missense mutation in the mitogen-activated protein kinase-like intestinal cell kinase (ICK) gene. In algae and invertebrates, ICK homologs are involved in flagellar formation and ciliogenesis, respectively. However, it is not clear whether this role of ICK is conserved in mammals and how a lack of functional ICK results in the characteristic phenotypes of human ECO syndrome. Here, we generated Ick knockout mice to elucidate the precise role of ICK in mammalian development and to examine the pathological mechanisms of ECO syndrome. Ick null mouse embryos displayed cleft palate, hydrocephalus, polydactyly, and delayed skeletal development, closely resembling ECO syndrome phenotypes. In cultured cells, down-regulation of Ick or overexpression of kinase-dead or ECO syndrome mutant ICK resulted in an elongation of primary cilia and abnormal Sonic hedgehog (Shh) signaling. Wild-type ICK proteins were generally localized in the proximal region of cilia near the basal bodies, whereas kinase-dead ICK mutant proteins accumulated in the distal part of bulged ciliary tips. Consistent with these observations in cultured cells, Ick knockout mouse embryos displayed elongated cilia and reduced Shh signaling during limb digit patterning. Taken together, these results indicate that ICK plays a crucial role in controlling ciliary length and that ciliary defects caused by a lack of functional ICK leads to abnormal Shh signaling, resulting in congenital disorders such as ECO syndrome.

Pannexin 3 is required for normal progression of skeletal development in vertebrates.

The vertebrate skeletal system has various functions, including support, movement, protection, and the production of blood cells. The development of cartilage and bones, the core components of the skeletal system, is mediated by systematic inter- and intracellular communication among multiple signaling pathways in differentiating progenitors and the surrounding tissues. Recently, Pannexin (Panx) 3 has been shown to play important roles in bone development in vitro by mediating multiple signaling pathways, although its roles in vivo have not been explored. In this study, we generated and analyzed Panx3 knockout mice and examined the skeletal phenotypes of panx3 morphant zebrafish. Panx3(-/-) embryos exhibited delays in hypertrophic chondrocyte differentiation and osteoblast differentiation as well as the initiation of mineralization, resulting in shortened long bones in adulthood. The abnormal progression of hypertrophic chondrogenesis appeared to be associated with the sustained proliferation of chondrocytes, which resulted from increased intracellular cAMP levels. Similarly, osteoblast differentiation and mineralization were delayed in panx3 morphant zebrafish. Taken together, our results provide evidence of the crucial roles of Panx3 in vertebrate skeletal development in vivo.

Retinoic acid signaling and the initiation of mammary gland development.

Retinoic acid receptors (RARs), which are involved in retinoic acid signal transduction, are essential for maintaining the differentiated state of epithelial tissues. Mammary glands are skin appendages whose development is initiated through continuous cell-cell interactions between the ectoderm and the adjacent mesenchyme. Considerable progress has been made in elucidating the molecular basis of these interactions in mammary gland formation in mouse embryos, including the network of initiating signals comprising Fgfs, Wnts and Bmps involved in gland positioning and the transcription factors, Tbx3 and Lef1, essential for mammary gland development. Here, we provide evidence that retinoic acid signaling may also be involved in mammary gland development. We documented the expression of gene-encoding enzymes that produce retinoic acid (Raldh2) and enzymes that degrade it (Cyp26a1, Cyp26b1). We also analyzed the expression of RAR-ß, a direct transcriptional target of retinoic acid signaling. Raldh2 and RAR-ß were expressed in E10-E10.5 mouse embryos in somites adjacent to the flank region where mammary buds 2, 3 and 4 develop. These expression patterns overlapped with that of Fgf10, which is known to be required for mammary gland formation. RAR-ß was also expressed in the mammary mesenchyme in E12 mouse embryos; RAR-ß protein was expressed in the mammary epithelium and developing fat pad. Retinoic acid levels in organ cultures of E10.5 mouse embryo flanks were manipulated by adding either retinoic acid or citral, a retinoic acid synthesis inhibitor. Reduced retinoic acid synthesis altered the expression of genes involved in retinoic acid homeostasis and also demonstrated that retinoic acid signaling is required for Tbx3 expression, whereas high levels of retinoic acid signaling inhibited Bmp4 expression and repressed Wnt signaling. The results of the experiments using RNAi against Tbx3 and Wnt10b suggested feedback interactions that regulate retinoic acid homeostasis in mammary gland-forming regions. We produced a molecular model for mammary gland initiation that incorporated retinoic acid signaling.

Gene Regulatory Networks and Signaling Pathways in Palatogenesis and Cleft Palate: A Comprehensive Review.

Palatogenesis is a complex and intricate process involving the formation of the palate through various morphogenetic events highly dependent on the surrounding context. These events comprise outgrowth of palatal shelves from embryonic maxillary prominences, their elevation from a vertical to a horizontal position above the tongue, and their subsequent adhesion and fusion at the midline to separate oral and nasal cavities. Disruptions in any of these processes can result in cleft palate, a common congenital abnormality that significantly affects patient's quality of life, despite surgical intervention. Although many genes involved in palatogenesis have been identified through studies on genetically modified mice and human genetics, the precise roles of these genes and their products in signaling networks that regulate palatogenesis remain elusive. Recent investigations have revealed that palatal shelf growth, patterning, adhesion, and fusion are intricately regulated by numerous transcription factors and signaling pathways, including Sonic hedgehog (Shh), bone morphogenetic protein (Bmp), fibroblast growth factor (Fgf), transforming growth factor beta (Tgf-ß), Wnt signaling, and others. These studies have also identified a significant number of genes that are essential for palate development. Integrated information from these studies offers novel insights into gene regulatory networks and dynamic cellular processes underlying palatal shelf elevation, contact, and fusion, deepening our understanding of palatogenesis, and facilitating the development of more efficacious treatments for cleft palate.

BMP4 signaling mediates Zeb family in developing mouse tooth.

Tooth morphogenesis is regulated by sequential and reciprocal interaction between oral epithelium and neural-crest-derived ectomesenchyme. The interaction is controlled by various signal molecules such as bone morphogenetic protein (BMP), Hedgehog, fibroblast growth factor (FGF), and Wnt. Zeb family is known as a transcription factor, which is essential for neural development and neural-crest-derived tissues, whereas the role of the Zeb family in tooth development remains unclear. Therefore, this study aimed to investigate the expression profiles of Zeb1 and Zeb2 during craniofacial development focusing on mesenchyme of palate, hair follicle, and tooth germ from E12.5 to E16.5. In addition, we examined the interaction between Zeb family and BMP4 during tooth development. Both Zeb1 and Zeb2 were expressed at mesenchyme of the palate, hair follicle, and tooth germ throughout the stages. In the case of tooth germ at the cap stage, the expression of Zeb1 and Zeb2 was lost in epithelium-separated dental mesenchyme. However, the expression of Zeb1 and Zeb2 in the dental mesenchyme was recovered by Bmp4 signaling via BMP4-soaked bead and tissue recombination. Our results suggest that Zeb1 and Zeb2, which were mediated by BMP4, play an important role in neural-crest-derived craniofacial organ morphogenesis, such as tooth development.

miR-200b regulates cell migration via Zeb family during mouse palate development.

Palate development requires coordinating proper cellular and molecular events in palatogenesis, including the epithelial-mesenchymal transition (EMT), apoptosis, cell proliferation, and cell migration. Zeb1 and Zeb2 regulate epithelial cadherin (E-cadherin) and EMT during organogenesis. While microRNA 200b (miR-200b) is known to be a negative regulator of Zeb1 and Zeb2 in cancer progression, its regulatory effects on Zeb1 and Zeb2 in palatogenesis have not yet been clarified. The aim of this study is to investigate the relationship between the regulators of palatal development, specifically, miR-200b and the Zeb family. Expression of both Zeb1 and Zeb2 was detected in the mesenchyme of the mouse palate, while miR-200b was expressed in the medial edge epithelium. After contact with the palatal shelves, miR-200b was expressed in the palatal epithelial lining and epithelial island around the fusion region but not in the palatal mesenchyme. The function of miR-200b was examined by overexpression via a lentiviral vector in the palatal shelves. Ectopic expression of miR-200b resulted in suppression of the Zeb family, upregulation of E-cadherin, and changes in cell migration and palatal fusion. These results suggest that miR-200b plays crucial roles in cell migration and palatal fusion by regulating Zeb1 and Zeb2 as a noncoding RNA during palate development.

The novel function of Oct3/4 in mouse tooth development.

Octamer-binding factor 3/4 (Oct3/4) is one of the key regulators maintaining the pluripotency and self-renewal in embryonic stem cells and is involved in the developmental events. However, the functional significance of Oct3/4 remains to be clarified during tooth morphogenesis. This study aimed to examine the functional role of Oct3/4 in mouse. During tooth morphogenesis (E11-E16.5), Oct3/4-positive cells, detected by nuclear immunoreaction, increased in number, and subsequently, their immunoreaction shifted from the nucleus to the cytoplasm at the stage of cell differentiation (E18.5). Quantitative real-time PCR clearly demonstrated the relationship between isoforms of Oct3/4 and the in vivo cellular localization of Oct3/4, suggesting that the Oct3/4 expressed in nucleus was Oct3/4A, whereas that expressed in the cytoplasm was Oct3/4B. RNAi knockdown of Oct3/4 induced apoptosis and arrested tooth morphogenesis. Our results suggest that (1) the increased number of Oct3/4-positive cells with nuclear immunoreaction correlate with active cell proliferation during tooth morphogenesis and (2) the shift of Oct3/4 from the nucleus to the cytoplasm plays a crucial role in cell differentiation.

MiR-200b is involved in Tgf-ß signaling to regulate mammalian palate development.

Various cellular and molecular events are involved in palatogenesis, including apoptosis, epithelial-mesenchymal transition (EMT), cell proliferation, and cell migration. Smad2 and Snail, which are well-known key mediators of the transforming growth factor beta (Tgf-ß) pathway, play a crucial role in the regulation of palate development. Regulatory effects of microRNA 200b (miR-200b) on Smad2 and Snail in palatogenesis have not yet been elucidated. The aim of this study is to determine the relationship between palate development regulators miR-200b and Tgf-ß-mediated genes. Expression of miR-200b, E-cadherin, Smad2, and Snail was detected in the mesenchyme of the mouse palate, while miR-200b was expressed in the medial edge epithelium (MEE) and palatal mesenchyme. After the contact of palatal shelves, miR-200b was no longer expressed in the mesenchyme around the fusion region. The binding activity of miR-200b to both Smad2 and Snail was examined using a luciferase assay. MiR-200b directly targeted Smad2 and Snail at both cellular and molecular levels. The function of miR-200b was determined by overexpression via a lentiviral vector in the palatal shelves. Ectopic expression of miR-200b resulted in suppression of these Tgf-ß-mediated regulators and changes of apoptosis and cell proliferation in the palatal fusion region. These results suggest that miR-200b plays a crucial role in regulating the Smad2, Snail, and in apoptosis during palatogenesis by acting as a direct non-coding, influencing factor. Furthermore, the molecular interactions between miR-200b and Tgf-ß signaling are important for proper palatogenesis and especially for palate fusion. Elucidating the mechanism of palatogenesis may aid the design of effective gene-based therapies for the treatment of congenital cleft palate.

The novel expression of Oct3/4 and Bmi1 in the root development of mouse molars.

The root apex of the tooth elongates until the completion of root development. Although the signaling molecules inducing root elongation have been studied, the characteristic of the cells having the ability to maintain the root elongation remains unclear. This study aimed to investigate the characteristics of the cells involved in the root elongation. Octamer-binding factor 3/4 (Oct3/4) is known as one of the key regulators in maintaining the pluripotency and self-renewal properties of embryonic stem cells. Bmi1, the polycomb-group transcriptional repressor, has emerged as a key regulator in several cellular processes including stem cell self-renewal and cancer cell proliferation. At the beginning of root formation, ameloblasts expressed Oct3/4 in the nucleus, except in the apex of the cervical loop, in which Bmi1and cyclinD were expressed. At PN6, the expression of Oct3/4 in the ameloblasts shifted from the nucleus to the cytoplasm, whereas ameloblastin-negative Hertwig's epithelial root sheath (HERS) cells expressed Bmi1 and cyclinD. By PN10, the cells in the apex of HERS began to express Oct3/4 in their nucleus, whereas Bmi1 and cyclinD began to decrease in their expressions. The odontoblasts consistently expressed Oct3/4 in their cytoplasm. Our results suggest that (1) Oct3/4 creates the border between the ameloblasts from the proliferative region of HERS, (2) Bmi1-positive cells would be one of the candidates resulting in root elongation and (3) the Oct3/4 expression in the cytoplasm of odontoblasts may be related to maintain the odontoblastic characteristics.

Runx3 is a crucial regulator of alveolar differentiation and lung tumorigenesis in mice.

The runt-domain transcription factor Runx3 plays crucial roles during development such as regulating gene expression. It has been shown that Runx3 is involved in neurogenesis, thymopoiesis and functions like a tumor suppressor. Runx3 null mouse die soon after birth as a result of multiple organ defects. Runx3 null mouse lung shows an abnormal phenotype and loss of Runx3 induced remodeling in the lung. Interestingly, lung adenocarcinoma is observed in Runx3 heterozygous mice at 18 months of age. During lung development various cellular and molecular events occur such as cell proliferation, cell death, differentiation and epithelial-mesenchymal transition (EMT). To understand the specific lethal events in Runx3 null mice, we examined cellular and molecular networks involved in EMT, and EMT inducers were quantified by RT-qPCR during lung development. Excessive EMT was observed in lungs at PN1 day in Runx3 null mice and PN18 months in Runx3 heterozygous mice. Pharmacologic inhibition of EMT was used to curb tumor progression. In this study, U0126 was injected to pregnant mouse for inhibition of pERK signaling. After U0126 treatment, life spans of newborn mice were increased and lung hyperplasia was partially rescued by down-regulated cell proliferation and EMT. Our data suggest that Runx3 is involved in crucial regulation of alveolar differentiation and tumor suppression in developing mouse lung.

Shh signaling is essential for rugae morphogenesis in mice.

Palatal ridges, or rugae palatinae, are corrugated structures observed in the hard palate region. They are found in most mammalian species, but their number and arrangement are species-specific. Nine palatal rugae are found in the mouse secondary palate. Previous studies have shown that epithelial Shh signaling in the palatal ridge plays an important role during rugae development. Moreover, Wnt family members, including LEF1, play a functional role in orofacial morphogenesis. To explore the function of Shh during rugae development, we utilized the maternal transfer of 5E1 (anti-Shh antibody) to mouse embryos. 5E1 induced abnormal rugae patterning characterized by a spotted shape of palatal ridge rather than a stripe. The expression patterns of Shh and Shh-related genes, Sostdc1, Lef1 and Ptch1, were disrupted following 5E1 injection. Moreover, rugae-specific cell proliferation and inter-rugae-specific apoptosis were affected by inhibition of Shh signaling. We hypothesize that the altered gene expression patterns and the change in molecular events caused by the inhibition of Shh signaling may have induced abnormal rugae patterning. Furthermore, we propose a reaction-diffusion model generated by Wnt, Shh and Sostdc1 signaling. In this study, we show that Sostdc1, a secreted inhibitor of the Wnt pathway, is a downstream target of Shh and hypothesize that the interaction of Wnt, Shh and Sostdc1 is a pivotal mechanism controlling the spatial patterning of palatal rugae.