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1.
Eur J Orthod ; 46(1)2024 Jan 01.
Article in English | MEDLINE | ID: mdl-37847809

ABSTRACT

BACKGROUND: Masticatory activity affects the morphology of the maxillo-mandibular complex, however, its influence on the cranial base remains to be elucidated. The recent integration of quantitative morphometric analysis with 3D imaging enabled a comprehensive and high-resolution morphological characterization of the craniofacial complex. We aimed to investigate the influence of masticatory activity on the morphology of the growing cranial base by three-dimensional (3D) geometric morphometric approach using micro-CT. METHODS: The micro-CT data was reanalyzed to illustrate the 3D shape of the cranial base, and wireframe models were generated by connecting landmarks on the images. In the original study, mice were fed a soft diet (SD) of powdered pellets or a conventional hard diet (HD) for 6 weeks from 3 to 9 weeks of age, immediately after weaning. A principal component (PC) analysis analyzed shape variations and assessed their significance, while canonical variate (CV) analysis facilitated the comparison and differentiation of groups based on shape, unveiling meaningful shape distinctions. RESULTS: Three PCs were extracted that significantly separated the SD and HD groups among those explaining variations in shape. These PCs were related to the length of the sphenoid bone, the width of the anterior part of the sphenoid bone, and the length of the cranial base. Furthermore, one CV effectively distinguished SD from HD, and CV analysis showed that the sphenoid was shortened in the length and narrowed at the border of the temporal bone in SD mice. CONCLUSIONS: Masticatory loading affects the skeletal development of the cranial base. The morphology of the sphenoid bone was affected in both the sagittal and transverse axes.


Subject(s)
Mandible , Skull Base , Mice , Animals , Skull Base/diagnostic imaging , Mandible/diagnostic imaging , X-Ray Microtomography , Diet , Imaging, Three-Dimensional
2.
Front Neurosci ; 17: 1178555, 2023.
Article in English | MEDLINE | ID: mdl-37575306

ABSTRACT

The dentate gyrus (DG) of the hippocampus regulates stress-related emotional behaviors and ensures neurogenesis throughout life. Neurotrophin-3 (NT-3) is a neurotrophic factor that regulates neuronal differentiation, survival, and synaptic formation in both the peripheral and central nervous systems. NT-3 is expressed in the adult DG of the hippocampus; several chronic stress conditions enhance NT-3 expression in rodents. However, functional modulation of the adult DG by NT-3 signaling remains unclear. To directly investigate the impact of NT-3 on DG function, NT-3 was overexpressed in the hippocampal ventral DG by an adeno-associated virus carrying NT-3 (AAV-NT-3). Four weeks following the AAV-NT-3 injection, high NT-3 expression was observed in the ventral DG. We examined the influence of NT-3 overexpression on the neuronal responses and neurogenic processes in the ventral DG. NT-3 overexpression significantly increased the expression of the mature DG neuronal marker calbindin and immediate early genes, such as Fos and Fosb, thereby suggesting DG neuronal activation. During neurogenesis, the number of proliferating cells and immature neurons in the subgranular zone of the DG significantly decreased in the AAV-NT-3 group. Among the neurogenesis-related factors, Vegfd, Lgr6, Bmp7, and Drd1 expression significantly decreased. These results demonstrated that high NT-3 levels in the hippocampus regulate the activation of mature DG neurons and suppress the early phase of neurogenic processes, suggesting a possible role of NT-3 in the regulation of adult hippocampal function under stress conditions.

3.
J Oral Biosci ; 64(2): 159-164, 2022 06.
Article in English | MEDLINE | ID: mdl-35231627

ABSTRACT

BACKGROUND: The development of dentition begins in the embryonic oral cavity and progresses in the branchial arches and alveolar bone. Continuous cellular and molecular crosstalk occurs during crown formation, after which the tooth germ begins to migrate apically through the alveolar process into the oral cavity. It eventually comes in contact with its antagonist in the contralateral jaw to establish functional occlusion. Any defect in either step can result in delayed tooth development, the spectrum of which varies from a congenitally missing tooth to an impacted tooth (infraocclusion) with an eruption problem, both of which can impair oral function. HIGHLIGHT: Congenitally missing teeth or eruption problems may result from genetic mutations. Several different mutations have been identified, each causing a distinct phenotype. Thus, it is imperative that medical providers understand the fundamentals of these genetic principles that govern such dental diseases. CONCLUSION: In this review, we focus on several diseases, including congenitally missing teeth and tooth eruption problems. We review these diseases with aspect to their association with a particular syndrome, as well as independently in a non-syndromic capacity. We also review previously identified genetic mutations and discuss the possible mechanisms that cause individual phenotypes by analyzing previous investigations. We also discuss future prospects of how genetic diagnosis and precision medicine could impact the clinical environment in the field of dentistry. ETHICAL APPROVAL: Present study has been carried out in accordance with The Code of Ethics of the World Medical Association and approved by Institutional Review Board of Osaka University Graduate School of Dentistry.


Subject(s)
Dentition , Tooth , Crowns , Dental Occlusion , Humans , Tooth Eruption/genetics
4.
J Ovarian Res ; 14(1): 87, 2021 Jun 29.
Article in English | MEDLINE | ID: mdl-34187525

ABSTRACT

BACKGROUND: Serous endometrial intraepithelial carcinoma (SEIC) is now considered to represent an early stage of uterine serous carcinoma (USC). It is an intraepithelial lesion but has been reported to cause extrauterine metastases. We report a case of SEIC with serous ovarian carcinoma and lymph node metastasis. CASE PRESENTATION: A 57-year-old post-menopausal woman (gravida 3, para 2, SA1) was referred to our hospital with lower abdominal pain. An ultrasound and MRI showed that the ovary had swollen to 8 cm in size and had a solid lesion. The uterus was normal. The patient underwent exploratory laparoscopy on the suspicion of torsion of the ovarian tumor. Intraoperative findings showed a right ovarian tumor, but no ovarian tumor torsion was observed. A small amount of bloody ascites was found in the Douglas fossa, and bleeding was observed from the tumor itself. A right salpingo-oophorectomy was then performed. Histopathological results revealed a high-grade serous carcinoma. Forty days after the first surgery, we performed a staging laparotomy: a total abdominal hysterectomy, left salpingo-oophorectomy, systematic pelvic and paraaortic lymphadenectomy, and a partial omentectomy. A complete cytoreduction was achieved. In the pathological examination, the invasion of the serous carcinoma was observed in the left ovarian ligament, and lymph node metastasis was found in the paraaortic lymph nodes. Atypical columnar cells formed irregular papillary lesions which had proliferated in the endometrium, and this was diagnosed as SEIC. The final diagnosis was serous ovarian cancer, FIGO stage IIIA1(ii), pT2bN1M0, with SEIC. CONCLUSION: We report a case of SEIC with synchronous serous carcinoma of the adnexa uteri. Both were serous carcinomas and, thus, it was difficult to identify the primary lesion. The distinction between metastatic cancer and two independent primary tumors is important for an accurate diagnosis and tumor staging. Histological diagnostic criteria remain controversial, and further development of a method for differentiating between both diseases is required.


Subject(s)
Carcinoma in Situ , Endometrial Neoplasms , Lymphatic Metastasis , Neoplasms, Multiple Primary , Ovarian Neoplasms , Carcinoma in Situ/diagnostic imaging , Carcinoma in Situ/pathology , Carcinoma in Situ/surgery , Endometrial Neoplasms/diagnostic imaging , Endometrial Neoplasms/pathology , Endometrial Neoplasms/surgery , Female , Humans , Lymphatic Metastasis/diagnostic imaging , Lymphatic Metastasis/pathology , Magnetic Resonance Imaging , Middle Aged , Neoplasms, Multiple Primary/diagnostic imaging , Neoplasms, Multiple Primary/pathology , Neoplasms, Multiple Primary/surgery , Ovarian Neoplasms/diagnostic imaging , Ovarian Neoplasms/pathology , Ovarian Neoplasms/surgery , Postmenopause , Ultrasonography
5.
Case Rep Obstet Gynecol ; 2020: 9106390, 2020.
Article in English | MEDLINE | ID: mdl-32850164

ABSTRACT

Primary peritoneal carcinosarcomas which arise from extragenital locations are extremely rare. Carinosarcomas contain both carcinomatous and sarcomatous elements and can be mainly detected in the female genital tract. We herein report a case of primary peritoneal carcinosarcoma diagnosed by laparoscopic surgery and treated with olaparib. A 62-year-old woman referred to our hospital due to abdominal distension. From imaging findings, we suspected advanced primary peritoneal carcinoma, and laparoscopic surgery was thereafter performed. The pathological diagnosis was carcinosarcoma, and the patient received chemotherapy with docetaxel and carboplatin. After three cycles of chemotherapy, the interval debulking surgery was attempted but resulted in suboptimal results. Because the bilateral ovaries were observed with a normal size and normal findings, we considered that the most likely diagnosis was primary peritoneal carcinosarcoma. After the additional chemotherapy and a 6-month observation period, the tumor relapsed. The patient received chemotherapy again, and the peritoneal carcinosarcoma was judged to be a platinum-sensitive tumor. Oral administration of olaparib was thus initiated. Although a dose reduction was needed due to anemia, olaparib was effective, and the patient could continue the drug for another 7 months. This is the first report of primary peritoneal carcinosarcoma treated with olaparib and shows that it could be a treatment option for platinum-sensitive tumors.

6.
iScience ; 23(4): 101025, 2020 Apr 24.
Article in English | MEDLINE | ID: mdl-32283526

ABSTRACT

The hippocampal mossy fiber (MF) synapse has been implicated in the pathophysiology and treatment of psychiatric disorders. Alterations of dopaminergic and serotonergic modulations at this synapse are candidate mechanisms underlying antidepressant and other related treatments. However, these monoaminergic modulations share the intracellular signaling pathway at the MF synapse, which implies redundancy in their functions. We here show that endogenous monoamines can potentiate MF synaptic transmission in mouse hippocampal slices by activating the serotonin 5-HT4 receptor. Dopamine receptors were not effectively activated by endogenous agonists, suggesting that the dopaminergic modulation is latent. Electroconvulsive treatment enhanced the 5-HT4 receptor-mediated serotonergic synaptic potentiation specifically at the MF synapse, increased the hippocampal serotonin content, and produced an anxiolytic-like behavioral effect in a 5-HT4 receptor-dependent manner. These results suggest that serotonin plays a predominant role in monoaminergic modulations at the MF synapse. Augmentation of this serotonergic modulation may mediate anxiolytic effects of electroconvulsive treatment.

7.
Eur J Orthod ; 42(5): 509-516, 2020 11 03.
Article in English | MEDLINE | ID: mdl-32346737

ABSTRACT

BACKGROUND AND OBJECTIVES: The masticatory force affects craniofacial development. We aimed to quantify the topological deviation of the growing craniofacial structure due to soft-food diet feeding and to map the region where the phenotypes appeared on three-dimensional (3D) images. MATERIAL AND METHODS: Mice were fed a powdered soft diet (SD) or conventional hard diet (HD) of regular rodent pellets at 3 weeks of age until 9 weeks of age. The heads, excluding the mandibles, were scanned by micro-computed tomography. The topographic deviation of the bony surface was quantitatively assessed by a wire mesh fitting analysis. The actual displacement and significant differences were mapped and visualized in each x-, y-, and z-axis on the 3D craniofacial image. On these reconstructed images, two-dimensional linear measurements between the landmark points confirmed the 3D skeletal displacement. RESULTS: In the transverse direction, the zygomatic arches and the region in which the temporal muscle attaches to the parietal and temporal bones were narrow in the SD group. The temporal muscle attachment regions significantly shifted anteriorly, and consequently, the sagittal zygomatic arch shortened. Although the cranial sagittal length was not affected, the vertical height was also reduced in the SD group compared to the HD group. CONCLUSIONS: Our 3D surface-based analysis demonstrated that SD feeding resulted in reduced 3D bony development at the region where the chewing muscles attach to the zygomatic arches and the temporal and parietal bones. Interestingly, SD feeding induced an anterior shift in the temporal and parietal bone regions, which can affect the skeletal inter-jaw relationship.


Subject(s)
Mastication , Zygoma , Animals , Diet , Imaging, Three-Dimensional , Mandible , Mice , X-Ray Microtomography , Zygoma/diagnostic imaging
8.
Dis Model Mech ; 12(6)2019 06 27.
Article in English | MEDLINE | ID: mdl-31171577

ABSTRACT

Core binding factor ß (Cbfb) is a cofactor of the Runx family of transcription factors. Among these transcription factors, Runx1 is a prerequisite for anterior-specific palatal fusion. It was previously unclear, however, whether Cbfb served as a modulator or as an obligatory factor in the Runx signaling process that regulates palatogenesis. Here, we report that Cbfb is essential and indispensable in mouse anterior palatogenesis. Palatal fusion in Cbfb mutants is disrupted owing to failed disintegration of the fusing epithelium specifically at the anterior portion, as observed in Runx1 mutants. In these mutants, expression of TGFB3 is disrupted in the area of failed palatal fusion, in which phosphorylation of Stat3 is also affected. TGFB3 protein has been shown to rescue palatal fusion in vitro TGFB3 also activated Stat3 phosphorylation. Strikingly, the anterior cleft palate in Cbfb mutants is further rescued by pharmaceutical application of folic acid, which activates suppressed Stat3 phosphorylation and Tgfb3 expression in vitro With these findings, we provide the first evidence that Cbfb is a prerequisite for anterior palatogenesis and acts as an obligatory cofactor in the Runx1/Cbfb-Stat3-Tgfb3 signaling axis. Furthermore, the rescue of the mutant cleft palate using folic acid might highlight potential therapeutic targets aimed at Stat3 modification for the prevention and pharmaceutical intervention of cleft palate.


Subject(s)
Cleft Palate/drug therapy , Cleft Palate/pathology , Core Binding Factor beta Subunit/deficiency , Folic Acid/therapeutic use , Animals , Cleft Palate/genetics , Core Binding Factor beta Subunit/metabolism , Epithelium/drug effects , Epithelium/pathology , Folic Acid/pharmacology , Gene Expression Regulation, Developmental/drug effects , Mice , Mice, Mutant Strains , Models, Biological , Mutation/genetics , Organogenesis/drug effects , Palate/abnormalities , Palate/embryology , Palate/pathology , Phenotype , RNA, Messenger/genetics , RNA, Messenger/metabolism , STAT3 Transcription Factor/metabolism , Transforming Growth Factor beta3/metabolism
9.
Hum Genome Var ; 6: 16, 2019.
Article in English | MEDLINE | ID: mdl-30962945

ABSTRACT

Basal cell nevus syndrome (BCNS) is a rare, multisystem, autosomal dominant disorder that is characterized by various phenotypes, including multiple basal cell carcinomas of the skin, odontogenic keratocysts of the jaws, and occasionally cleft lip and/or palate. In this report, we describe a 6-year-old Japanese girl with a novel heterozygous nonsense mutation in PTCH1 who exhibited rare craniofacial phenotypes, such as oligodontia and a short-tooth root.

10.
Biomed Res Int ; 2019: 2916243, 2019.
Article in English | MEDLINE | ID: mdl-31930115

ABSTRACT

Nonalcoholic fatty liver disease (NAFLD) is characterized by a spectrum of liver pathologies, from simple steatosis to steatohepatitis. Recent studies have increasingly noted the aberrant expression of microRNAs closely related to NAFLD pathologies. We have previously shown the presence of increased levels of microRNA-27b (miR-27b) in patients with NAFLD. In this study, we investigated the role of miR-27b in NAFLD by examining the impact of up-regulated miR-27b on the differentiation of preadipocytes into mature adipocytes. We found that miR-27b-3p remarkably enhances the adipocyte differentiation of 3T3-L1 cells associated with lipid accumulation and intracellular triglyceride contents. Furthermore, we have demonstrated not only that miR-27b-3p induces acyl-CoA thioesterase 2 (ACOT2) expression in 3T3-L1 cells, but also that the knockdown of ACOT2 suppresses lipid accumulation and adipocyte differentiation in both the presence and absence of miR-27b-3p treatment. Our data strongly suggest that the miR-27b-ACOT2 axis is an important pathway in adipocyte differentiation and may play a role in the pathogenesis of NAFLD.


Subject(s)
Adipocytes/pathology , Cell Differentiation/genetics , MicroRNAs/genetics , Palmitoyl-CoA Hydrolase/genetics , Up-Regulation/genetics , 3T3-L1 Cells , Adipogenesis/genetics , Animals , Cell Line , Mice , Non-alcoholic Fatty Liver Disease/genetics , Non-alcoholic Fatty Liver Disease/pathology , RNA Interference/physiology , Transcriptional Activation/genetics
11.
Am J Hypertens ; 32(2): 216-222, 2019 01 15.
Article in English | MEDLINE | ID: mdl-30265283

ABSTRACT

BACKGROUND: Recently, attention has been focused on the cardiovascular protective effects of beet juice (BJ) with high amounts of nitrate. In this study, we examined the effect of BJ supplementation in a rat model of monocrotaline (MCT)-induced pulmonary hypertension (PH). METHODS: MCT (60 mg/kg) was subcutaneously administered to rats, and BJ (prepared by dissolving BJ powder at a concentration of 1 g/l or 10 g/l in drinking water) supplementation was started from the day of, 1 week before, and 2 weeks after MCT injection. Saline-injected rats given drinking water were used as controls. RESULTS: Low-dose BJ supplementation starting from the day of MCT injection exerted protective effects on the MCT-induced elevation of right ventricular systolic pressure, right ventricular hypertrophy, and pulmonary arterial remodeling, without causing a significant increase in plasma nitrite plus nitrate (NOx) levels. On the other hand, such beneficial effects were not observed with high-dose BJ supplementation, although the NOx levels were slightly higher than those in the low-dose group. In addition, low-dose BJ supplementation starting from 1 week before MCT injection did not improve PH symptoms, as described above. Furthermore, low-dose BJ supplementation starting from 2 weeks after MCT injection was ineffective against functional and morphological alterations in pulmonary circulation associated with MCT-induced PH. CONCLUSIONS: Habitual ingestion of a suitable amount of BJ could be a potential option for preventing PH. However, beneficial effects cannot be expected when PH has developed to some degree.


Subject(s)
Arterial Pressure , Beta vulgaris , Dietary Supplements , Fruit and Vegetable Juices , Pulmonary Arterial Hypertension/prevention & control , Pulmonary Artery/physiopathology , Animals , Disease Models, Animal , Hypertrophy, Right Ventricular/chemically induced , Hypertrophy, Right Ventricular/physiopathology , Hypertrophy, Right Ventricular/prevention & control , Male , Monocrotaline , Nitric Oxide/metabolism , Plant Roots , Pulmonary Arterial Hypertension/chemically induced , Pulmonary Arterial Hypertension/metabolism , Pulmonary Arterial Hypertension/physiopathology , Pulmonary Artery/metabolism , Rats, Sprague-Dawley , Vascular Remodeling , Ventricular Dysfunction, Right/chemically induced , Ventricular Dysfunction, Right/physiopathology , Ventricular Dysfunction, Right/prevention & control , Ventricular Function, Right
12.
Lipids Health Dis ; 12: 122, 2013 Aug 09.
Article in English | MEDLINE | ID: mdl-23937951

ABSTRACT

BACKGROUND: Various inflammatory mediators related to obesity might be closely related to insulin resistance. Leukotrienes (LTs) are involved in inflammatory reactions. However, there are few reports regarding the role of LTs in adipocyte differentiation. Therefore, we investigated the role of leukotriene B4 (LTB4)-leukotriene receptor (BLT) signaling in mouse 3T3-L1 fibroblastic preadipocyte differentiation to mature adipocytes. METHODS: Mouse 3T3-L1 preadipocytes were treated with lipoxygenase (LOX) inhibitors, BLT antagonist, and small interfering RNA (siRNA) for BLT1 and BLT2 to block the LTB4-BLT signaling pathway, then the adipocyte differentiation such as lipid accumulation and the increase in triglyceride was evaluated. RESULTS: Blockade of BLT signaling by treatment with a LOX inhibitor or a BLT antagonist suppressed preadipocyte differentiation into mature adipocytes. In addition, knockdown of BLT1 and BLT2 by siRNAs dramatically inhibited differentiation. These results indicate the LTB4-BLT signaling pathway may positively regulate preadipocyte differentiation and be a rate-limiting system to control adipocyte differentiation. CONCLUSIONS: The LTB4-BLT signaling pathway provides a potent regulatory signal that accelerates the differentiation of mouse 3T3-L1 preadipocytes. Further investigations are necessary to confirm the exact role of LTB4 and BLTs signaling pathways in preadipocyte differentiation.


Subject(s)
Adipocytes/metabolism , Leukotriene B4/metabolism , Obesity/genetics , Receptors, Leukotriene B4/metabolism , 3T3-L1 Cells , Adipocytes/drug effects , Animals , Cell Differentiation/drug effects , Cell Differentiation/genetics , Insulin Resistance/genetics , Leukotriene B4/genetics , Lipoxygenase/genetics , Lipoxygenase/metabolism , Lipoxygenase Inhibitors/administration & dosage , Mice , Obesity/metabolism , Obesity/pathology , RNA, Small Interfering , Receptors, Leukotriene B4/genetics , Signal Transduction/drug effects , Signal Transduction/genetics
13.
Radiat Med ; 25(3): 113-8, 2007 Apr.
Article in English | MEDLINE | ID: mdl-17450335

ABSTRACT

PURPOSE: The aim of this study was to investigate how accurately we could diagnose the level of gastrointestinal (GI) tract perforation using multidetector computed tomography (MDCT). MATERIALS AND METHODS: We reviewed 155 patients with surgically confirmed GI tract perforation. MDCT scans were obtained with eight-detector CT; 5 mm thick axial images and 2.5 mm thick coronal multiplanar reconstruction (MPR) images were generated for all patients. Contrast enhancement was performed in 44 of the 155 patients. Two board-certified radiologists reviewed the images for direct findings (free air, ruptured GI tract wall) and indirect findings (inflammatory changes, fluid collection, focal thickening of the GI tract wall) and attempted to identify the perforation site in each patient. RESULTS: Free air was seen in more than 95% of the patients with perforation at sites other than the appendix; free air was seen in 44% of patients with appendicitis. On contrast-enhanced CT performed in 44 patients, rupture of the wall of the GI tract was directly visualized in 14 (32%) on axial images only and in 23 (52%) on axial or MPR images, respectively. The perforation site was correctly diagnosed in 90% of the patients when the radiologists referred to both direct and indirect findings. CONCLUSION: MDCT was valuable for identifying the presence and level of GI tract perforation.


Subject(s)
Intestinal Perforation/diagnostic imaging , Tomography, X-Ray Computed/methods , Adolescent , Adult , Aged , Aged, 80 and over , Contrast Media/administration & dosage , Female , Humans , Intestinal Perforation/surgery , Iohexol/administration & dosage , Male , Middle Aged , Radiography, Abdominal
14.
Radiat Med ; 21(2): 86-93, 2003.
Article in English | MEDLINE | ID: mdl-12816356

ABSTRACT

BACKGROUND AND PURPOSE: To assess chronological change in intracranial artery dissections with magnetic resonance imaging (MRI), MR angiography (MRA), and source images of MRA, and to determine whether the source images of MRA provide additional useful information to the combined evaluation of MRI and MRA. MATERIALS AND METHODS: Seven consecutive patients with intracranial artery dissections who were diagnosed by clinical history and conventional angiography were followed sequentially with MRI and MRA (mean follow-up duration, 8.8 months). Two observers independently reviewed the signal intensity of the arterial wall on T1-weighted images, luminal structures on MRA, and source images of MRA. RESULTS: In three (43%) of seven patients, the affected arterial wall had high signal intensity area from 4 to 62 days after onset on T-weighted images. Double lumen on MRA wasobserved only in one patient during the course of the study, whereas a definite low-intensity linear area in the lumen on source images of MRA was seen from 0 to 773 days after onset in all patients. When information from the source images of MRA was added to evaluation with both MRI and MRA, detectability increased to 100% from day 0 to day 3 and 67% from day 4 to day 30. CONCLUSION: The signal intensity of the dissected wall and the luminal structures on MRA and its source images vary according to chronological age. The use of source images from MRA in addition to the combined evaluation of MRI and MRA may provide more accurate diagnosis and follow-up study of intracranial artery dissections.


Subject(s)
Aortic Dissection/diagnosis , Arteries/pathology , Magnetic Resonance Angiography , Magnetic Resonance Imaging , Skull/blood supply , Adult , Aged , Female , Humans , Male , Middle Aged , Retrospective Studies
15.
Kidney Int ; 61(6): 1968-79, 2002 Jun.
Article in English | MEDLINE | ID: mdl-12028437

ABSTRACT

UNLABELLED: Role of membrane-bound heparin-binding epidermal growth factor-like growth factor (HB-EGF) in renal epithelial cell branching. BACKGROUND: The developing metanephros is characterized by growth and differentiation of the ureteric bud and the surrounding mesenchymal tissue. These processes can be influenced by several growth factors, including epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha). We examined whether another member of the EGF family of growth factors, heparin-binding epidermal growth factor (HB-EGF), might act as a morphogen in renal epithelial tubulogenesis. METHODS: Expression of HB-EGF mRNA and immunoreactive protein were examined in fetal, neonatal and adult rat kidneys. For in vitro studies of tubulogenesis, a rat renal epithelial cell line (NRK52E) stably transfected with proHB-EGF (NRKproHB-EGF) was treated with TPA for 30 minutes, washed with 2 mol/L NaCl to remove soluble HB-EGF trapped by cell surface heparan sulfate proteoglycan and replated onto plastic dishes in the absence of fetal calf serum. In further experiments, NRKproHB-EGF were suspended in a type I collagen gel in serum-free media. RESULTS: Northern blot analysis indicated that HB-EGF was strongly expressed in embryonic rat kidney (embryonic days 18-20) and was still increased in the neonatal kidney (day 10), compared to the low basal levels in adult kidney. Immunohistochemical analysis confirmed that immunoreactive HB-EGF expression in the fetal rat kidney was localized predominantly to the ureteric bud. When NRKproHB-EGF were plated onto plastic substrata, they became progressively flattened and enlarged and exhibited filopoidia. By 10 hours after plating, NRKproHB-EGF began to migrate and subsequently developed cell-cell contact and fully established tubular-like structures. Immunoelectron microscopy revealed that the initial recovery of cellular proHB-EGF was localized predominantly to areas of cell-cell attachment. No tubule-like structures were observed in similarly treated NRK52E cells transfected with the vector alone. In collagen gels, NRKproHB-EGF developed short tubule-like structures in the absence of TPA treatment, but with simultaneous TPA treatment, longer and more arborized structures developed. MMP-1 mRNA and immunoreactive protein increased in the TPA-treated cells, suggesting that protein kinase C-mediated collagenase activity was important for the observed tubulogenesis. However, inhibition of EGF receptor tyrosine kinase with AG 1478 significantly blunted the TPA-induced tubulogenesis by NRKproHB-EGF grown in collagen gels. CONCLUSIONS: These results indicate that membrane-bound HB-EGF can mediate both epithelial cell branching and cell motility. Localization of proHB-EGF to the site of cell-cell contact and development of tubule-like structures in collagen gels suggests that proHB-EGF may be an important morphogen for renal epithelial cells.


Subject(s)
Epidermal Growth Factor/physiology , Kidney/cytology , Animals , Animals, Newborn/metabolism , Cell Division/physiology , Cell Line , Cell Membrane/metabolism , Cell Movement/physiology , Collagen , Culture Media , Embryo, Mammalian/metabolism , Embryo, Mammalian/physiology , Embryonic and Fetal Development , Epithelial Cells/cytology , Gels , Heparin-binding EGF-like Growth Factor , Intercellular Signaling Peptides and Proteins , Kidney/embryology , Kidney/metabolism , Kidney Tubules/embryology , Male , Protein Precursors/physiology , Rats , Rats, Sprague-Dawley , Tissue Distribution , Ureter/embryology
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