Publications by authors named "Juhee Jeong"

26 Publications

  • Page 1 of 1

Tumor-Infiltrating Neutrophils and Non-Classical Monocytes May Be Potential Therapeutic Targets for HER2 Gastric Cancer.

Immune Netw 2021 Aug 20;21(4):e31. Epub 2021 Aug 20.

Department of Anatomy and Cell Biology, Seoul National University College of Medicine, Seoul 03080, Korea.

Gastric cancer (GC) is the fourth most common cause of cancer-related death globally. The classification of advanced GC (AGC) according to molecular features has recently led to effective personalized cancer therapy for some patients. Specifically, AGC patients whose tumor cells express high levels of human epidermal growth factor receptor 2 (HER2) can now benefit from trastuzumab, a humanized monoclonal Ab that targets HER2. However, patients with HER2 AGC receive limited clinical benefit from this treatment. To identify potential immune therapeutic targets in HER2 AGC, we obtained 40 fresh AGC specimens immediately after surgical resections and subjected the CD45 immune cells in the tumor microenvironment to multi-channel/multi-panel flow cytometry analysis. Here, we report that HER2 negativity associated with reduced overall survival (OS) and greater tumor infiltration with neutrophils and non-classical monocytes. The potential pro-tumoral activities of these cell types were confirmed by the fact that high expression of neutrophil or non-classical monocyte signature genes in the gastrointestinal tumors in The Cancer Genome Atlas, Genotype-Tissue Expression and Gene Expression Omnibus databases associated with worse OS on Kaplan-Meir plots relative to tumors with low expression of these signature genes. Moreover, advanced stage disease in the AGCs of our patients associated with greater tumor frequencies of neutrophils and non-classical monocytes than early stage disease. Thus, our study suggests that these 2 myeloid populations may serve as novel therapeutic targets for HER2 AGC.
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http://dx.doi.org/10.4110/in.2021.21.e31DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8410991PMC
August 2021

R-Spondin 3 Regulates Mammalian Dental and Craniofacial Development.

J Dev Biol 2021 Aug 12;9(3). Epub 2021 Aug 12.

Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY 10010, USA.

Development of the teeth requires complex signaling interactions between the mesenchyme and the epithelium mediated by multiple pathways. For example, canonical WNT signaling is essential to many aspects of odontogenesis, and inhibiting this pathway blocks tooth development at an early stage. R-spondins (RSPOs) are secreted proteins, and they mostly augment WNT signaling. Although RSPOs have been shown to play important roles in the development of many organs, their role in tooth development is unclear. A previous study reported that mutating in mice led to supernumerary lower molars, while teeth forming at the normal positions showed no significant anomalies. Because multiple genes are expressed in the orofacial region, it is possible that the relatively mild phenotype of mutants is due to functional compensation by other RSPO proteins. We found that inactivating in the craniofacial mesenchyme caused the loss of lower incisors, which did not progress beyond the bud stage. A simultaneous deletion of and caused severe disruption of craniofacial development from early stages, which was accompanied with impaired development of all teeth. Together, these results indicate that is an important regulator of mammalian dental and craniofacial development.
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http://dx.doi.org/10.3390/jdb9030031DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8395884PMC
August 2021

Recent advances in intravital microscopy for investigation of dynamic cellular behavior in vivo.

BMB Rep 2020 Jul;53(7):357-366

Department of Biomedical Sciences, BK21 Plus Biomedical Science Project, Seoul National University College of Medicine, Seoul 03080; Department of Anatomy and Cell Biology, Seoul National University College of Medicine, Seoul 03080; Institute of Allergy and Clinical Immunology, Seoul National University Medical Research Center, Seoul 03080, Korea.

Currently, most biological research relies on conventional experimental techniques that allow only static analyses at certain time points in vitro or ex vivo. However, if one could visualize cellular dynamics in living organisms, that would provide a unique opportunity to study key biological phenomena in vivo. Intravital microscopy (IVM) encompasses diverse optical systems for direct viewing of objects, including biological structures and individual cells in live animals. With the current development of devices and techniques, IVM addresses important questions in various fields of biological and biomedical sciences. In this mini-review, we provide a general introduction to IVM and examples of recent applications in the field of immunology, oncology, and vascular biology. We also introduce an advanced type of IVM, dubbed real-time IVM, equipped with video-rate resonant scanning. Since the realtime IVM can render cellular dynamics with high temporal resolution in vivo, it allows visualization and analysis of rapid biological processes. [BMB Reports 2020; 53(7): 357-366].
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7396917PMC
July 2020

Switching of Sox9 expression during musculoskeletal system development.

Sci Rep 2020 05 21;10(1):8425. Epub 2020 May 21.

Department of Anatomy, Tokyo Dental College, 2-9-18 Misaki-cho, Chiyoda-ku, Tokyo, 101-0061, Japan.

The musculoskeletal system, which comprises muscles, tendons, and bones, is an efficient tissue complex that coordinates body movement and maintains structural stability. The process of its construction into a single functional and complex organization is unclear. SRY-box containing gene 9 (Sox9) is expressed initially in pluripotent cells and subsequently in ectodermal, endodermal, and mesodermal derivatives. This study investigated how Sox9 controls the development of each component of the musculoskeletal system. Sox9 was expressed in MTJ, tendon, and bone progenitor cells at E13 and in bone at E16. We detected Sox9 expression in muscle progenitor cells using double-transgenic mice and myoblastic cell lines. However, we found no Sox9 expression in developed muscle. A decrease in Sox9 expression in muscle-associated connective tissues, tendons, and bones led to hypoplasia of the cartilage and its attachment to tendons and muscle. These results showed that switching on Sox9 expression in each component (muscle, tendon, and bone) is essential for the development of the musculoskeletal system. Sox9 is expressed in not only tendon and bone progenitor cells but also muscle progenitor cells, and it controls musculoskeletal system development.
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http://dx.doi.org/10.1038/s41598-020-65339-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7242482PMC
May 2020

Morphological association between the muscles and bones in the craniofacial region.

PLoS One 2020 10;15(1):e0227301. Epub 2020 Jan 10.

Department of Anatomy, Tokyo Dental College, Tokyo, Japan.

The strains of inbred laboratory mice are isogenic and homogeneous for over 98.6% of their genomes. However, geometric morphometric studies have demonstrated clear differences among the skull shapes of various mice strains. The question now arises: why are skull shapes different among the mice strains? Epigenetic processes, such as morphological interaction between the muscles and bones, may cause differences in the skull shapes among various mice strains. To test these predictions, the objective of this study is to examine the morphological association between a specific part of the skull and its adjacent muscle. We examined C57BL6J, BALB/cA, and ICR mice on embryonic days (E) 12.5 and 16.5 as well as on postnatal days (P) 0, 10, and 90. As a result, we found morphological differences between C57BL6J and BALB/cA mice with respect to the inferior spine of the hypophyseal cartilage or basisphenoid (SP) and the tensor veli palatini muscle (TVP) during the prenatal and postnatal periods. There was a morphological correlation between the SP and the TVP in the C57BL6J, BALB/cA, and ICR mice during E15 and P0. However, there were not correlation between the TVP and the SP during P10. After discectomy, bone deformation was associated with a change in the shape of the adjacent muscle. Therefore, epigenetic modifications linked to the interaction between the muscles and bones might occur easily during the prenatal period, and inflammation seems to allow epigenetic modifications between the two to occur.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0227301PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6953862PMC
May 2020

Context Drives Diversification of Monocytes and Neutrophils in Orchestrating the Tumor Microenvironment.

Front Immunol 2019 16;10:1817. Epub 2019 Aug 16.

Lab of Cancer Immunology and In Vivo Imaging, Department of Biomedical Sciences, BK21 Plus Biomedical Science Project, Seoul National University College of Medicine, Seoul, South Korea.

Recent preclinical/clinical studies have underscored the significant impact of tumor microenvironment (TME) on tumor progression in diverse scenarios. Highly heterogeneous and complex, the tumor microenvironment is composed of malignant cancer cells and non-malignant cells including endothelial cells, fibroblasts, and diverse immune cells. Since immune compartments play pivotal roles in regulating tumor progression via various mechanisms, understanding of their multifaceted functions is crucial to developing effective cancer therapies. While roles of lymphoid cells in tumors have been systematically studied for a long time, the complex functions of myeloid cells have been relatively underexplored. However, constant findings on tumor-associated myeloid cells are drawing attention, highlighting the primary effects of innate immune cells such as monocytes and neutrophils in disease progression. This review focuses on hitherto identified contextual developments and functions of monocytes and neutrophils with a special interest in solid tumors. Moreover, ongoing clinical applications are discussed at the end of the review.
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http://dx.doi.org/10.3389/fimmu.2019.01817DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6706790PMC
October 2020

Molecular patterning of the embryonic cranial mesenchyme revealed by genome-wide transcriptional profiling.

Dev Biol 2019 11 24;455(2):434-448. Epub 2019 Jul 24.

Department of Basic Science and Craniofacial Biology, New York University College of Dentistry, New York, NY, 10010, USA. Electronic address:

In the head of an embryo, a layer of mesenchyme surrounds the brain underneath the surface ectoderm. This cranial mesenchyme gives rise to the meninges, the calvaria (top part of the skull), and the dermis of the scalp. Abnormal development of these structures, especially the meninges and the calvaria, is linked to significant congenital defects in humans. It has been known that different areas of the cranial mesenchyme have different fates. For example, the calvarial bone develops from the cranial mesenchyme on the baso-lateral side of the head just above the eye (supraorbital mesenchyme, SOM), but not from the mesenchyme apical to SOM (early migrating mesenchyme, EMM). However, the molecular basis of this difference is not fully understood. To answer this question, we compared the transcriptomes of EMM and SOM using high-throughput sequencing (RNA-seq). This experiment identified a large number of genes that were differentially expressed in EMM and SOM, and gene ontology analyses found very different terms enriched in each region. We verified the expression of about 40 genes in the head by RNA in situ hybridization, and the expression patterns were annotated to make a map of molecular markers for 6 subdivisions of the cranial mesenchyme. Our data also provided insights into potential novel regulators of cranial mesenchyme development, including several axon guidance pathways, lectin complement pathway, cyclic-adenosine monophosphate (cAMP) signaling pathway, and ZIC family transcription factors. Together, information in this paper will serve as a unique resource to guide future research on cranial mesenchyme development.
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http://dx.doi.org/10.1016/j.ydbio.2019.07.015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6842427PMC
November 2019

Developmental biology of the meninges.

Genesis 2019 05 13;57(5):e23288. Epub 2019 Mar 13.

New York University College of Dentistry, Department of Basic Science and Craniofacial Biology, New York, New York.

The meninges are membranous layers surrounding the central nervous system. In the head, the meninges lie between the brain and the skull, and interact closely with both during development. The cranial meninges originate from a mesenchymal sheath on the surface of the developing brain, called primary meninx, and undergo differentiation into three layers with distinct histological characteristics: the dura mater, the arachnoid mater, and the pia mater. While genetic regulation of meningeal development is still poorly understood, mouse mutants and other models with meningeal defects have demonstrated the importance of the meninges to normal development of the calvaria and the brain. For the calvaria, the interactions with the meninges are necessary for the progression of calvarial osteogenesis during early development. In later stages, the meninges control the patterning of the skull and the fate of the sutures. For the brain, the meninges regulate diverse processes including cell survival, cell migration, generation of neurons from progenitors, and vascularization. Also, the meninges serve as a stem cell niche for the brain in the postnatal life. Given these important roles of the meninges, further investigation into the molecular mechanisms underlying meningeal development can provide novel insights into the coordinated development of the head.
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http://dx.doi.org/10.1002/dvg.23288DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6520190PMC
May 2019

Development of a Rapid Automated Fluorescent Lateral Flow Immunoassay to Detect Hepatitis B Surface Antigen (HBsAg), Antibody to HBsAg, and Antibody to Hepatitis C.

Ann Lab Med 2018 Nov;38(6):578-584

Department of Laboratory Medicine, College of Medicine, Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Korea.

Background: Accurate, rapid, and cost-effective screening tests for hepatitis B virus (HBV) and hepatitis C virus (HCV) infection may be useful in laboratories that cannot afford automated chemiluminescent immunoassays (CLIAs). We evaluated the diagnostic performance of a novel rapid automated fluorescent lateral flow immunoassay (LFIA).

Methods: A fluorescent LFIA using a small bench-top fluorescence reader, Automated Fluorescent Immunoassay System (AFIAS; Boditech Med Inc., Chuncheon, Korea), was developed for qualitative detection of hepatitis B surface antigen (HBsAg), antibody to HBsAg (anti-HBs), and antibody to HCV (anti-HCV) within 20 minutes. We compared the diagnostic performance of AFIAS with that of automated CLIAs-Elecsys (Roche Diagnostics GmbH, Penzberg, Germany) and ARCHITECT (Abbott Laboratories, Abbott Park, IL, USA)-using 20 seroconversion panels and 3,500 clinical serum samples.

Results: Evaluation with the seroconversion panels demonstrated that AFIAS had adequate sensitivity for HBsAg and anti-HCV detection. From the clinical samples, AFIAS sensitivity and specificity were 99.8% and 99.3% for the HBsAg test, 100.0% and 100.0% for the anti-HBs test, and 98.8% and 99.1% for the anti-HCV test, respectively. Its agreement rates with the Elecsys HBsAg, anti-HBs, and anti-HCV detection assays were 99.4%, 100.0%, and 99.0%, respectively. AFIAS detected all samples with HBsAg genotypes A-F and H and anti-HCV genotypes 1, 1a, 1b, 2a, 2b, 4, and 6. Cross-reactivity with other infections was not observed.

Conclusions: The AFIAS HBsAg, anti-HBs, and anti-HCV tests demonstrated diagnostic performance equivalent to current automated CLIAs. AFIAS could be used for a large-scale HBV or HCV screening in low-resource laboratories or low-to middle-income areas.
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http://dx.doi.org/10.3343/alm.2018.38.6.578DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6056386PMC
November 2018

Anti-osteogenic function of a LIM-homeodomain transcription factor LMX1B is essential to early patterning of the calvaria.

Dev Biol 2018 11 28;443(2):103-116. Epub 2018 May 28.

Department of Basic Science and Craniofacial Biology, New York University College of Dentistry, New York, NY, United States. Electronic address:

The calvaria (upper part of the skull) is made of plates of bone and fibrous joints (sutures and fontanelles), and the proper balance and organization of these components are crucial to normal development of the calvaria. In a mouse embryo, the calvaria develops from a layer of head mesenchyme that surrounds the brain from shortly after mid-gestation. The mesenchyme just above the eye (supra-orbital mesenchyme, SOM) generates ossification centers for the bones, which then grow toward the apex gradually. In contrast, the mesenchyme apical to SOM (early migrating mesenchyme, EMM), including the area at the vertex, does not generate an ossification center. As a result, the dorsal midline of the head is occupied by sutures and fontanelles at birth. To date, the molecular basis for this regional difference in developmental programs is unknown. The current study provides vital insights into the genetic regulation of calvarial patterning. First, we showed that osteogenic signals were active in both EMM and SOM during normal development, which suggested the presence of an anti-osteogenic factor in EMM to counter the effect of these signals. Subsequently, we identified Lmx1b as an anti-osteogenic gene that was expressed in EMM but not in SOM. Furthermore, head mesenchyme-specific deletion of Lmx1b resulted in heterotopic ossification from EMM at the vertex, and craniosynostosis affecting multiple sutures. Conversely, forced expression of Lmx1b in SOM was sufficient to inhibit osteogenic specification. Therefore, we conclude that Lmx1b plays a key role as an anti-osteogenic factor in patterning the head mesenchyme into areas with different osteogenic competence. In turn, this patterning event is crucial to generating the proper organization of the bones and soft tissue joints of the calvaria.
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http://dx.doi.org/10.1016/j.ydbio.2018.05.022DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6197925PMC
November 2018

Efficacy evaluation of syringe pump developed for continuous drug infusion.

J Dent Anesth Pain Med 2016 Dec 31;16(4):303-307. Epub 2016 Dec 31.

Medical Device Development Center, Daegu-Gyeongbuk Medical Innovation Foundation, Daegu, Korea.

Background: In dental intravenous sedation, continuous intravenous infusion of a low-dose drug requires an infusion pump such as a syringe pump. To develop a new syringe pump for clinical use, the functions of the pump must meet certain international standards. Various safety and efficacy tests must be performed on the syringe pump, as stipulated by these standards, and an approval must be received from the approving agency based on such test results.

Methods: The authors of the present study developed a novel syringe pump and performed efficacy evaluation by testing its infusion speed at 1 and 25 ml/h, and infusion performance testing at 2 and 24 h. Moreover, performance evaluation was conducted by comparing the novel pump to an existing pump with the infusion speed varied from 1 to 5 ml/h.

Results: In the efficacy testing on the newly developed syringe pump, infusion with the infusion speed initially set to 1 ml/h resulted in infusion speeds of 1.00 and 0.99 ml/h in the 2- and 24-h assessment, respectively. Changing the infusion speed setting to 25 ml/h resulted in an infusion speed of 25.09 and 23.92 ml/h in the 2- and 24-h assessment, respectively. These results show no significant differences when compared with other commercially available pumps.

Conclusions: The efficacy testing of the newly developed syringe pump showed the accuracy to be within tolerance. Based on these findings, we believe that the newly developed syringe pump is suitable for clinical use.
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http://dx.doi.org/10.17245/jdapm.2016.16.4.303DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5564196PMC
December 2016

Expression of forkhead box transcription factor genes Foxp1 and Foxp2 during jaw development.

Gene Expr Patterns 2016 03 9;20(2):111-9. Epub 2016 Mar 9.

Department of Basic Science and Craniofacial Biology, New York University College of Dentistry, 345 East 24th Street, New York, NY 10010 United States. Electronic address:

Development of the face is regulated by a large number of genes that are expressed in temporally and spatially specific patterns. While significant progress has been made on characterizing the genes that operate in the oral region of the face, those regulating development of the aboral (lateral) region remain largely unknown. Recently, we discovered that transcription factors LIM homeobox (LHX) 6 and LHX8, which are key regulators of oral development, repressed the expression of the genes encoding forkhead box transcription factors, Foxp1 and Foxp2, in the oral region. To gain insights into the potential role of the Foxp genes in region-specific development of the face, we examined their expression patterns in the first pharyngeal arch (primordium for the jaw) of mouse embryos at a high spatial and temporal resolution. Foxp1 and Foxp2 were preferentially expressed in the aboral and posterior parts of the first pharyngeal arch, including the developing temporomandibular joint. Through double immunofluorescence and double fluorescent RNA in situ hybridization, we found that Foxp1 was expressed in the progenitor cells for the muscle, bone, and connective tissue. Foxp2 was expressed in subsets of bone and connective tissue progenitors but not in the myoblasts. Neither gene was expressed in the dental mesenchyme nor in the oral half of the palatal shelf undergoing extensive growth and morphogenesis. Together, we demonstrated for the first time that Foxp1 and Foxp2 are expressed during craniofacial development. Our data suggest that the Foxp genes may regulate development of the aboral and posterior regions of the jaw.
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http://dx.doi.org/10.1016/j.gep.2016.03.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4842334PMC
March 2016

Lhx6 and Lhx8 promote palate development through negative regulation of a cell cycle inhibitor gene, p57Kip2.

Hum Mol Genet 2015 Sep 12;24(17):5024-39. Epub 2015 Jun 12.

Department of Basic Science and Craniofacial Biology, New York University College of Dentistry, New York, NY 10010, USA,

Cleft palate is a common birth defect in humans. Therefore, understanding the molecular genetics of palate development is important from both scientific and medical perspectives. Lhx6 and Lhx8 encode LIM homeodomain transcription factors, and inactivation of both genes in mice resulted in profound craniofacial defects including cleft secondary palate. The initial outgrowth of the palate was severely impaired in the mutant embryos, due to decreased cell proliferation. Through genome-wide transcriptional profiling, we discovered that p57(Kip2) (Cdkn1c), encoding a cell cycle inhibitor, was up-regulated in the prospective palate of Lhx6(-/-);Lhx8(-/-) mutants. p57(Kip2) has been linked to Beckwith-Wiedemann syndrome and IMAGe syndrome in humans, which are developmental disorders with increased incidents of palate defects among the patients. To determine the molecular mechanism underlying the regulation of p57(Kip2) by the Lhx genes, we combined chromatin immunoprecipitation, in silico search for transcription factor-binding motifs, and in vitro reporter assays with putative cis-regulatory elements. The results of these experiments indicated that LHX6 and LHX8 regulated p57(Kip2) via both direct and indirect mechanisms, with the latter mediated by Forkhead box (FOX) family transcription factors. Together, our findings uncovered a novel connection between the initiation of palate development and a cell cycle inhibitor via LHX. We propose a model in which Lhx6 and Lhx8 negatively regulate p57(Kip2) expression in the prospective palate area to allow adequate levels of cell proliferation and thereby promote normal palate development. This is the first report elucidating a molecular genetic pathway downstream of Lhx in palate development.
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http://dx.doi.org/10.1093/hmg/ddv223DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4527495PMC
September 2015

A novel function for Egr4 in posterior hindbrain development.

Sci Rep 2015 Jan 13;5:7750. Epub 2015 Jan 13.

Department of Basic Science &Craniofacial Biology, College of Dentistry, New York University, New York, USA.

Segmentation of the vertebrate hindbrain is an evolutionarily conserved process. Here, we identify the transcription factor early growth response 4 (egr4) as a novel regulator of posterior hindbrain development in Xenopus. egr4 is specifically and transiently expressed in rhombomeres 5 and 6 (r5/r6), and Egr4 knockdown causes a loss of mafb/kreisler and krox20/egr2 expression in r5/r6 and r5, respectively. This phenotype can be fully rescued by injection of frog or mouse Egr4 mRNA. Moreover Egr4-depleted embryos exhibit a specific loss of the neural crest stream adjacent to r5, and have inner ear defects. While the homeodomain protein vHnf1/Hnf1b directly activates Mafb and Krox20 expression in the mouse hindbrain to specify r5, we show that in Xenopus this process is indirect through the activation of Egr4. We provide evidence that rearrangements in the regulatory sequences around egr4 and mafb genes may account for this difference.
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http://dx.doi.org/10.1038/srep07750DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4291570PMC
January 2015

Identification of a face enhancer reveals direct regulation of LIM homeobox 8 (Lhx8) by wingless-int (WNT)/β-catenin signaling.

J Biol Chem 2014 Oct 4;289(44):30289-30301. Epub 2014 Sep 4.

Department of Basic Science and Craniofacial Biology, New York University College of Dentistry, New York, New York 10010 and. Electronic address:

Development of the mammalian face requires a large number of genes that are expressed with spatio-temporal specificity, and transcriptional regulation mediated by enhancers plays a key role in the precise control of gene expression. Using chromatin immunoprecipitation for a histone marker of active enhancers, we generated a genome-wide map of candidate enhancers from the maxillary arch (primordium for the upper jaw) of mouse embryos. Furthermore, we confirmed multiple novel craniofacial enhancers near the genes implicated in human palate defects through functional assays. We characterized in detail one of the enhancers (Lhx8_enh1) located upstream of Lhx8, a key regulatory gene for craniofacial development. Lhx8_enh1 contained an evolutionarily conserved binding site for lymphoid enhancer factor/T-cell factor family proteins, which mediate the transcriptional regulation by the WNT/β-catenin signaling pathway. We demonstrated in vitro that WNT/β-catenin signaling was indeed essential for the expression of Lhx8 in the maxillary arch cells and that Lhx8_enh1 was a direct target of the WNT/β-catenin pathway. Together, we uncovered a molecular mechanism for the regulation of Lhx8, and we provided valuable resources for further investigation into the gene regulatory network of craniofacial development.
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http://dx.doi.org/10.1074/jbc.M114.592014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4215213PMC
October 2014

Neural crest-specific deletion of Ldb1 leads to cleft secondary palate with impaired palatal shelf elevation.

BMC Dev Biol 2014 Jan 17;14. Epub 2014 Jan 17.

Department of Basic Science and Craniofacial Biology, New York University College of Dentistry, 10010 New York, NY, USA.

Background: LIM domain binding protein 1 (LDB1) is a transcriptional co-factor, which interacts with multiple transcription factors and other proteins containing LIM domains. Complete inactivation of Ldb1 in mice resulted in early embryonic lethality with severe patterning defects during gastrulation. Tissue-specific deletions using a conditional knockout allele revealed additional roles of Ldb1 in the development of the central nervous system, hematopoietic system, and limbs. The goal of the current study was to determine the importance of Ldb1 function during craniofacial development in mouse embryos.

Results: We generated tissue-specific Ldb1 mutants using Wnt1-Cre, which causes deletion of a floxed allele in the neural crest; neural crest-derived cells contribute to most of the mesenchyme of the developing face. All examined Wnt1-Cre;Ldb1(fl/-) mutants suffered from cleft secondary palate. Therefore, we performed a series of experiments to investigate how Ldb1 regulated palate development. First, we examined the expression of Ldb1 during normal development, and found that Ldb1 was expressed broadly in the palatal mesenchyme during early stages of palate development. Second, we compared the morphology of the developing palate in control and Ldb1 mutant embryos using sections. We found that the mutant palatal shelves had abnormally blunt appearance, and failed to elevate above the tongue at the posterior domain. An in vitro head culture experiment indicated that the elevation defect was not due to interference by the tongue. Finally, in the Ldb1 mutant palatal shelves, cell proliferation was abnormal in the anterior, and the expression of Wnt5a, Pax9 and Osr2, which regulate palatal shelf elevation, was also altered.

Conclusions: The function of Ldb1 in the neural crest-derived palatal mesenchyme is essential for normal morphogenesis of the secondary palate.
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http://dx.doi.org/10.1186/1471-213X-14-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3899388PMC
January 2014

Cleft palate defect of Dlx1/2-/- mutant mice is caused by lack of vertical outgrowth in the posterior palate.

Dev Dyn 2012 Nov 28;241(11):1757-69. Epub 2012 Sep 28.

Department of Basic Science and Craniofacial Biology, New York University College of Dentistry, New York, NY 10010, USA.

Background: Mice lacking the activities of Dlx1 and Dlx2 (Dlx1/2-/-) exhibit cleft palate, one of the most common human congenital defects, but the etiology behind this phenotype has been unknown. Therefore, we analyzed the morphological, cellular, and molecular changes caused by inactivation of Dlx1 and Dlx2 as related to palate development.

Results: Dlx1/2-/- mutants exhibited lack of vertical growth in the posterior palate during the earliest stage of palatogenesis. We attributed this growth deficiency to reduced cell proliferation. Expression of a cell cycle regulator Ccnd1 was specifically down-regulated in the same region. Previous studies established that the epithelial-mesenchymal signaling loop involving Shh, Bmp4, and Fgf10 is important for cell proliferation and tissue growth during palate development. This signaling loop was disrupted in Dlx1/2-/- palate. Interestingly, however, the decreases in Ccnd1 expression and mitosis in Dlx1/2-/- mutants were independent of this signaling loop. Finally, Dlx1/2 activity was required for normal expression of several transcription factor genes whose mutation results in palate defects.

Conclusions: The functions of Dlx1 and Dlx2 are crucial for the initial formation of the posterior palatal shelves, and that the Dlx genes lie upstream of multiple signaling molecules and transcription factors important for later stages of palatogenesis.
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http://dx.doi.org/10.1002/dvdy.23867DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3988582PMC
November 2012

Signaling by SHH rescues facial defects following blockade in the brain.

Dev Dyn 2012 Feb;241(2):247-56

Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, California, USA.

Background: The Frontonasal Ectodermal Zone (FEZ) is a signaling center in the face that expresses Sonic hedgehog (Shh) and regulates patterned growth of the upper jaw. Blocking SHH in the forebrain blocks Shh expression in the FEZ and creates malformations resembling holoprosencephaly (HPE), while inhibition of BMP signaling in the mesenchyme blocks FEZ formation and causes similar dysmorphology. Thus, the brain could regulate FEZ formation by SHH or BMP signaling, and if so, activating one of these pathways in the face might alleviate the effects of repression of SHH in the brain.

Results: We blocked SHH signaling in the brain while adding SHH or BMP between the neural and facial ectoderm of the frontonasal process. When applied early, SHH restored Shh expression in the FEZ and significantly improved shape outcomes, which contrasts with our previous experiments that showed later SHH treatments have no effect. BMP-soaked beads introduced early and late caused apoptosis that exacerbated malformations. Finally, removal of Smoothened from neural crest cells did not inhibit Shh expression in the FEZ.

Conclusions: Collectively, this work suggests that a direct, time-sensitive SHH signal from the brain is required for the later induction of Shh in the FEZ. We propose a testable model of FEZ activation and discuss signaling mediators that may regulate these interactions.
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http://dx.doi.org/10.1002/dvdy.23726DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3547623PMC
February 2012

Lhx6 and Lhx8 coordinately induce neuronal expression of Shh that controls the generation of interneuron progenitors.

Neuron 2011 Jun;70(5):939-50

Department of Psychiatry and the Nina Ireland Laboratory of Developmental Neurobiology, University of California, San Francisco, San Francisco, CA 94158-2324, USA.

Lhx6 and Lhx8 transcription factor coexpression in early-born MGE neurons is required to induce neuronal Shh expression. We provide evidence that these transcription factors regulate expression of a Shh enhancer in MGE neurons. Lhx6 and Lhx8 are also required to prevent Nkx2-1 expression in a subset of pallial interneurons. Shh function in early-born MGE neurons was determined by genetically eliminating Shh expression in the MGE mantle zone (MZ). This mutant had reduced SHH signaling in the overlying progenitor zone, which led to reduced Lhx6, Lhx8, and Nkx2-1 expression in the rostrodorsal MGE and a preferential reduction of late-born somatostatin(+) and parvalbumin(+) cortical interneurons. Thus, Lhx6 and Lhx8 regulate MGE development through autonomous and nonautonomous mechanisms, the latter by promoting Shh expression in MGE neurons, which in turn feeds forward to promote the developmental program of the rostrodorsal MGE.
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http://dx.doi.org/10.1016/j.neuron.2011.04.020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3153409PMC
June 2011

Dlx genes pattern mammalian jaw primordium by regulating both lower jaw-specific and upper jaw-specific genetic programs.

Development 2008 Sep;135(17):2905-16

Department of Psychiatry, Nina Ireland Laboratory of Developmental Neurobiology, University of California San Francisco, 1550 4th street, San Francisco, CA 94158, USA.

Dlx transcription factors are implicated in patterning the mammalian jaw, based on their nested expression patterns in the first branchial arch (primordium for jaw) and mutant phenotypes; inactivation of Dlx1 and Dlx2 (Dlx1/2-/-) causes defects in the upper jaw, whereas Dlx5/6(-/-) results in homeotic transformation of the lower jaw into upper jaw. Therefore, the 'Dlx codes' appear to regionalize the jaw primordium such that Dlx1/2 regulate upper jaw development, while Dlx5/6 confer the lower jaw fate. Towards identifying the genetic pathways downstream of Dlx5/6, we compared the gene expression profiles of the wild-type and Dlx5/6(-/-) mouse mandibular arch (prospective lower jaw). We identified 20 previously unrecognized Dlx5/6-downstream genes, of which 12 were downregulated and 8 upregulated in the mutant. We found a Dlx-regulated transcriptional enhancer in close proximity to Gbx2, one of the Dlx5/6-downstream genes, strongly suggesting that Gbx2 is a direct target of Dlx5/6. We also showed that Pou3f3 is normally expressed in the maxillary (prospective upper jaw) but not mandibular arch, is upregulated in the mandibular arch of Dlx5/6(-/-), and is essential for formation of some of the maxillary arch-derived skeleton. A comparative analysis of the morphological and molecular phenotypes of various Dlx single and double mutants revealed that Dlx1, 2, 5 and 6 act both partially redundantly and antagonistically to direct differential expression of downstream genes in each domain of the first branchial arch. We propose a new model for Dlx-mediated mammalian jaw patterning.
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http://dx.doi.org/10.1242/dev.019778DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4913551PMC
September 2008

Notochord-derived Shh concentrates in close association with the apically positioned basal body in neural target cells and forms a dynamic gradient during neural patterning.

Development 2008 Mar 13;135(6):1097-106. Epub 2008 Feb 13.

Department of Molecular and Cellular Biology, The Biolabs, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA.

Sonic hedgehog (Shh) ligand secreted by the notochord induces distinct ventral cell identities in the adjacent neural tube by a concentration-dependent mechanism. To study this process, we genetically engineered mice that produce bioactive, fluorescently labeled Shh from the endogenous locus. We show that Shh ligand concentrates in close association with the apically positioned basal body of neural target cells, forming a dynamic, punctate gradient in the ventral neural tube. Both ligand lipidation and target field response influence the gradient profile, but not the ability of Shh to concentrate around the basal body. Further, subcellular analysis suggests that Shh from the notochord might traffic into the neural target field by means of an apical-to-basal-oriented microtubule scaffold. This study, in which we directly observe, measure, localize and modify notochord-derived Shh ligand in the context of neural patterning, provides several new insights into mechanisms of Shh morphogen action.
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http://dx.doi.org/10.1242/dev.013086DOI Listing
March 2008

Mouse Disp1 is required in sonic hedgehog-expressing cells for paracrine activity of the cholesterol-modified ligand.

Development 2005 Jan 2;132(1):133-42. Epub 2004 Dec 2.

One DNA Way, Genentech Incorporated, South San Francisco, CA 94080, USA.

Previous studies have demonstrated that Disp1 function is essential for Shh and Ihh signaling in the mouse, and Disp1 gene dose regulates the level of Shh signaling activity in vivo. To determine whether Disp1 activity is required in Shh-producing cells for paracrine signaling in Shh target fields, we used a ShhGFP-Cre (here shortened to ShhCre) knock-in allele and a Disp1 conditional allele to knock down Disp1 activity specifically within Shh-producing cells. The resulting facial and neural tube phenotypes support the conclusion that the primary and probably exclusive role for Disp1 is within hedgehog protein-producing cells. Furthermore, using an allele that produces N-Shh (a noncholesterol modified form of the Shh protein), we demonstrate that N-Shh is sufficient to rescue most of the early embryonic lethal defects in a Disp1-null mutant background. Thus, Disp1 activity is only required for paracrine hedgehog protein signaling by the cholesterol modified form of Shh (N-Shhp), the normal product generated by auto-processing of a Shh precursor protein. In both respects, Disp function is conserved from Drosophila to mice.
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http://dx.doi.org/10.1242/dev.01563DOI Listing
January 2005

Growth and pattern of the mammalian neural tube are governed by partially overlapping feedback activities of the hedgehog antagonists patched 1 and Hhip1.

Development 2005 Jan 2;132(1):143-54. Epub 2004 Dec 2.

Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.

Upregulation of Patched (Ptc), the Drosophila Hedgehog (Hh) receptor in response to Hh signaling limits the range of signaling within a target field by sequestering Hh. In vertebrates, Ptch1 also exhibits ligand-dependent transcriptional activation, but mutants lacking this response show surprisingly normal early development. The identification of Hh-interacting protein 1 (Hhip1), a vertebrate-specific feedback antagonist of Hh signaling, raises the possibility of overlapping feedback controls. We addressed the significance of feedback systems in sonic hedgehog (Shh)-dependent spinal cord patterning. Mouse embryos lacking both Ptch1 and Hhip1 feedback activities exhibit severe patterning defects consistent with an increased magnitude and range of Hh signaling, and disrupted growth control. Thus, Ptc/Ptch1-dependent feedback control of Hh morphogens is conserved between flies and mice, but this role is shared in vertebrates with Hhip1. Furthermore, this feedback mechanism is crucial in generating a neural tube that contains appropriate numbers of all ventral and intermediate neuronal cell types.
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http://dx.doi.org/10.1242/dev.01566DOI Listing
January 2005

Hedgehog signaling in the neural crest cells regulates the patterning and growth of facial primordia.

Genes Dev 2004 Apr;18(8):937-51

Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.

Facial abnormalities in human SHH mutants have implicated the Hedgehog (Hh) pathway in craniofacial development, but early defects in mouse Shh mutants have precluded the experimental analysis of this phenotype. Here, we removed Hh-responsiveness specifically in neural crest cells (NCCs), the multipotent cell type that gives rise to much of the skeleton and connective tissue of the head. In these mutants, many of the NCC-derived skeletal and nonskeletal components are missing, but the NCC-derived neuronal cell types are unaffected. Although the initial formation of branchial arches (BAs) is normal, expression of several Fox genes, specific targets of Hh signaling in cranial NCCs, is lost in the mutant. The spatially restricted expression of Fox genes suggests that they may play an important role in BA patterning. Removing Hh signaling in NCCs also leads to increased apoptosis and decreased cell proliferation in the BAs, which results in facial truncation that is evident by embryonic day 11.5 (E11.5). Together, our results demonstrate that Hh signaling in NCCs is essential for normal patterning and growth of the face. Further, our analysis of Shh-Fox gene regulatory interactions leads us to propose that Fox genes mediate the action of Shh in facial development.
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http://dx.doi.org/10.1101/gad.1190304DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC395852PMC
April 2004

The morphogen sonic hedgehog is an axonal chemoattractant that collaborates with netrin-1 in midline axon guidance.

Cell 2003 Apr;113(1):11-23

Department of Biological Sciences, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA.

Developing axons are guided to their targets by attractive and repulsive guidance cues. In the embryonic spinal cord, the floor plate chemoattractant Netrin-1 is required to guide commissural neuron axons to the midline. However, genetic evidence suggests that other chemoattractant(s) are also involved. We show that the morphogen Sonic hedgehog (Shh) can mimic the additional chemoattractant activity of the floor plate in vitro and can act directly as a chemoattractant on isolated axons. Cyclopamine-mediated inhibition of the Shh signaling mediator Smoothened (Smo) or conditional inactivation of Smo in commissural neurons indicate that Smo activity is important for the additional chemoattractant activity of the floor plate in vitro and for the normal projection of commissural axons to the floor plate in vivo. These results provide evidence that Shh, acting via Smo, is a midline-derived chemoattractant for commissural axons and show that a morphogen can also act as an axonal chemoattractant.
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http://dx.doi.org/10.1016/s0092-8674(03)00199-5DOI Listing
April 2003

Cholesterol modification of Hedgehog family proteins.

J Clin Invest 2002 Sep;110(5):591-6

Department of Molecular and Cellular Biology, The Biolabs, Harvard University, Cambridge, Massachusetts 02138, USA.

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http://dx.doi.org/10.1172/JCI16506DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC151115PMC
September 2002
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