Kyoung-Won Cho

Data mining approach to policy analysis in a health insurance domain

This study examined the characteristics of the knowledge discovery and data mining algorithms to demonstrate how they can be used to predict health outcomes and provide policy information for hypertension management using the Korea Medical Insurance Corporation database. Specifically, this study validated the predictive power of data mining algorithms by comparing the performance of logistic regression and two decision tree algorithms, CHIAD (Chi-squared Automatic Interaction Detection) and C5.0 (a variant of C4.5) using the test set of 4588 beneficiaries and the training set of 13,689 beneficiaries. Contrary to the previous study, the CHIAD algorithm performed better than the logistic regression in predicting hypertension, and C5.0 had the lowest predictive power. In addition, the CHIAD algorithm and the association rule also provided the segment-specific information for the risk factors and target group that may be used in a policy analysis for hypertension management.

Molecular interactions between Tbx3 and Bmp4 and a model for dorsoventral positioning of mammary gland development

The formation of the dorsoventral (DV) boundary is central to establishing the body plan in embryonic development. Although there is some information about how limbs are positioned along the DV axis and how DV skin color pattern is determined, the way in which mammary glands are positioned is unknown. Here we focus on Bmp4 and Tbx3, a gene associated with ulnar-mammary syndrome, and compare their expression along the DV axis in relation to mammary gland initiation in mouse embryos. Tbx3 is expressed in the mammary gland-forming region with Tbx15, a gene involved in a DV coat color being expressed more dorsally and Bmp4 being expressed more ventrally. When Tbx3 was overexpressed, formation of mammary gland epithelium was extended along the DV axis. In contrast, overexpression of Bmp4 inhibited both Tbx3 and Tbx15 expression. In addition, when BMP signaling was inhibited by NOGGIN, Lef1 expression was lost. Thus, we propose that mutual interactions between Bmp4 and Tbx3 determine the presumptive DV boundary and formation of mammary glands in early mouse embryogenesis. 1,19-Dioctadecyl-3,3,39,39-tetramethyl indocarbocyanine perchloride labeling experiments showed that cells associated with mammary glands originate more dorsally and then move ventrally. This finding, together with previous findings, suggests that the same DV boundary may not only position limbs and determine coat color but also position mammary glands. Furthermore, Bmp signaling appears to be a fundamental feature of DV patterning.

Wnt11/Fgfr1b cross-talk modulates the fate of cells in palate development.

Various cellular and molecular events underlie the elevation and fusion of the developing palate that occurs during embryonic development. This includes convergent extension, where the medial edge epithelium is intercalated into the midline epithelial seam. We examined the expression patterns of Wnt11 and Fgfr1b - which are believed to be key factors in convergent extension - in mouse palate development. Wnt-11 overexpression and beads soaked in SU5402 (an Fgfr1 inhibitor) were employed in in vitro organ cultures. The results suggested that interactions between Wnt11 and Fgfr1b are important in modulating cellular events such as cell proliferation for growth and apoptosis for fusion. Moreover, the Wnt11 siRNA results showed that Wnt11-induced apoptosis was necessary for palatal fusion. In summary, Fgfr1b induces cell proliferation in the developing palate mesenchyme so that the palate grows and contacts each palatal shelf, with negative feedback of Fgfs triggered by excessive cell proliferation then inhibiting the expression of Fgfr1b and activating the expression of Wnt11 to fuse each palate by activating apoptosis.

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-β, a direct transcriptional target of retinoic acid signaling. Raldh2 and RAR-β 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-β was also expressed in the mammary mesenchyme in E12 mouse embryos; RAR-β 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.

Shh and ROCK1 modulate the dynamic epithelial morphogenesis in circumvallate papilla development.

In rodents, a circumvallate papilla (CVP) develops with dynamic changes in epithelial morphogenesis during early tongue development. Molecular and cellular studies of CVP development revealed that there would be two different mechanisms in the apex and the trench wall forming regions with specific expression patterns of Wnt11 and Shh. Molecular interactions were examined using in vitro organ culture with over-expression of Shh, important signalling molecules and various inhibitors revealed that there are two significant different mechanisms in CVP formation by Wnt11 and Shh expressions. Wnt, a well known key molecule to initiate taste papillae, would govern Rho activation and cytoskeleton formation in the apex epithelium of CVP. In contrast, Shh regulates the cell proliferation to differentiate taste buds and to invaginate the epithelium for development of von Ebners gland (VEG). Based on these results, we suggest that these different molecular signalling cascades of Wnt11 and Shh would play crucial roles in specific morphogenesis and pattern formation of CVP during early mouse embryo development.

The forkhead transcription factor Foxc2 stimulates osteoblast differentiation

The forkhead box C2 (Foxc2) protein is a member of the family of winged helix/forkhead transcription factors. Foxc2-deficient mice display defective formation of the aortic arches, multiple craniofacial bones, and vertebral columns. To investigate the role of Foxc2 in osteoblast differentiation, DNA containing Foxc2 was transfected into the developing cranial suture mesenchymal cells by electroporation. Compared to the controls, alkaline phosphatase (ALP) and bone sialoprotein were expressed strongly in suture mesenchymal cells in the Foxc2 overexpressed calvaria. After Foxc2-siRNA transfection, ALP staining was rarely observed in the suture mesenchyme and adjacent parietal bone of the calvaria. Meanwhile, overexpression of Foxc2 increased protein levels of beta-catenin and stimulated TCF/LEF transcriptional activity. The protein kinase A inhibitor H-89 suppressed Foxc2-mediated increases in TCF/LEF transcriptional activity (-40%, P<0.01). In conclusion, our results demonstrated that Foxc2 stimulated osteoblast differentiation of mesenchymal cells and preosteoblasts. Activation of canonical Wnt-beta-catenin signals might be involved in the Foxc2-mediated stimulation of osteoblast differentiation.

The forkhead transcription factor Foxc2 promotes osteoblastogenesis via up-regulation of integrin β1 expression

The forkhead box C2 (Foxc2) protein, a member of the forkhead/winged helix transcription factor family, plays an important role in regulation of metabolism, arterial specification, and vascular sprouting. Foxc2-null mutants die prenatally or perinatally, and they exhibit hypoplasia of the vertebrae and insufficient chondrification or ossification of medial structures. However, the role of Foxc2 in osteoblastogenesis is not yet fully understood. According to the degree of differentiation of osteoblasts, we found that Foxc2 expression was gradually increased and dose-dependently up-regulated by well-known bone anabolic agents, such as hPTH(1-34) and BMP2. In ex vivo mouse calvarial organ culture, a significant reduction of the basal expression of Foxc2 induced by siFoxc2 remarkably suppressed cell proliferation and differentiation and induced cell death. Knockdown of Foxc2 expression using siFoxc2 in both MC3T3-E1 and primary mouse calvarial cells also resulted in a significant suppression of proliferation and differentiation, and induced cell death, supporting the ex vivo observations. In addition, the resistance to apoptosis induced by serum deprivation and phosphorylation of both Akt and ERK was significantly reduced after siFoxc2 treatment. Conversely, overexpression of Foxc2 increased the proliferation of MC3T3-E1 and primary mouse calvarial cells. Furthermore, we found that Foxc2 enhanced the expression of integrin β1, an important modulator of osteoblastogenesis, by direct binding to a Forkhead-binding element in its promoter. Taken together, these results indicate that Foxc2 plays an important role in osteoblastogenesis by promoting osteoblast proliferation, survival and differentiation through up-regulation of integrin β1 in response to stimuli which induce bone formation.

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.

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.

MiR-200b is involved in Tgf-β 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-β) 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-β-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-β-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-β 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.