Objective: To explore the molecular mechanism of cleft palate in mice induced by 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD). Methods: The pregnant mice were randomly divided into TCDD-treated group (n=42) and control group (n=42). TCDD-treated group was given by gavage a single dose of TCDD (64 μg/kg) at 8: 00 AM on gestation day 10 (GD10) and the control group was given by gavage the isopyknic corn oil. At GD13-GD15, the fetal mice palate development was observed by HE staining. The mouse embryonic palatal mesenchymal cell proliferation was detected by 5-bromo-2-deoxyuridine (BrdU) immunofluorescence. The localization and expression of maternally expressed gene3 (MEG3) in mouse embryonic palatal mesenchymal cells was detected by situ hybridization and real-time PCR (RT-PCR). The key protein expressions of transforming growth factor-β (TGF-β)/Smad signaling pathway in mouse embryonic palatal mesenchyme were analyzed by Western blotting. The interaction of MEG3 and TGF-β receptor Ⅰ (TGF-βRⅠ) was examined by RNA binding protein immunoprecipitation (RIP). Results: At GD13 and GD14, compared with the control group, the ratio of BrdU-positive cells in the palatal mesenchyme of TCDD-treated fetuses decreased significantly (GD13, t=6.66, P=0.003; GD14, t=6.56, P=0.003). However, at GD15, the ratio of BrdU-positive cells was significantly increased (t=-5.98, P=0.004). MEG3 was mainly expressed in the nuclei of fetal mouse palatal mesenchymal cells, and the expression of MEG3 in TCDD group was significantly increased at GD13, GD14 and GD15(GD13, t=39.28, P=0.012; GD14, t=18.75, P=0.042; GD15, t=28.36, P=0.045). At GD14, TCDD decreased the levels of p-Smad2 and Smad4 in embryonic palate mesenchymal cells (p-Smad2, t=9.48, P=0.001;Smad4, t=63.10, P=0.001), whereas the expression of Smad7 was significantly increased at GD14 (t=30.77, P<0.001). The results of the RIP experiment showed that the amount of TGF-βRⅠ-bound MEG3 in mouse embryonic palatal mesenchymal cells in the TCDD group (23.940±1.301) was higher than that in the control group (8.537±1.523)(t=24.55, P<0.001). Conclusions: MEG3 is involved in the suppression of mouse embryonic palatal mesenchymal cell proliferation, functioning at least in part via interacting with the TGF-βRⅠ protein and thereby suppressing Smad signaling in the context of TCDD induced cleft palate.
Animals ; Bromodeoxyuridine ; Cleft Palate/genetics* ; Female ; Mice ; Mice, Inbred C57BL ; Palate/metabolism* ; Polychlorinated Dibenzodioxins/toxicity* ; Pregnancy

OBJECTIVETo study the mechanism of new bone formation and remodeling of distraction osteogenesis (DO) by analysis of the expression of osteopontin (OPN) and osteocalcin (OC).

METHODSRhesus were operated to reconstruct the animal model of cleft palate (CP). The CP was closed by DO in experimental group(n = 21). After consolidation of 1, 2, 4, 6, 8, 12, 24 weeks, every 3 animals were killed to collect the specimens, respectively. The OPN and OC and their mRNA were detected quantitatively by Real-time RT-PCR and ELISA, respectively. The animals in control group (n = 2) and sham group (n = 2) were used as control.

RESULTSThe mRNA expression of OPN increased since 2nd week of consolidation and reached the peak at 4th week (7.59 +/- 0.37). The mRNA expression of OC was up-regulated since 4th week, and reach the peak at 6th week (7.94 +/- 0.31). Then they decreased to about the level in sham group at 24th week (P > 0.05). The OPN and OC were highly expressed during 4 to 6 weeks of consolidation. During 8 to 12 weeks, they decreased like their mRNA expression.

CONCLUSIONThe intramembraneous new bone formation after DO can reconstruct the bone defect of CP. The new formed bone can be remodeled to be quite normal bone tissue.

Animals ; Cleft Palate ; metabolism ; surgery ; Macaca mulatta ; Osteocalcin ; metabolism ; Osteogenesis, Distraction ; Osteopontin ; metabolism

OBJECTIVEThe purpose of this study was to observe the roentgenographic characters of distraction osteogenesis (DO) correction of cleft palate (CP), to study the expression of BMP proportional to fixation period time intervals, and to explore the new bone formation mechanism in Cleft Palate bone shelf.

METHODS12 cats were used to establish the CP animal model surgically, and then were assigned randomly to (1) Experimental group (12 cats): CP defects were DO repaired at the rate and rhythm of 0.4 mm x 2/day. Specimen retrieval at 2, 4, 6, 8, 12 weeks after completion of distraction, roentgenography and Anti-BMP immunohistochemistry studies were performed; (2) Experimental control group (2 cats): CP defects without any treatment procedures, and (3) Empty control group of 2 cats.

RESULTSAnti-BMP immunohistochemistry study showed positive DAB dye in early 2 weeks and most extensively positive expression of BMP in 4 to 6 weeks. The expression of BMP wore off gradually through 8 to 12 weeks. The roentgenography showed that the newly mineralized bone was developed from the cut bone edges bilaterally to the central transparent zone, and the newly formed bone bridged the defect area completely at the end of the study. The CP bone defect was reconstructed and the distraction gap was filled with de nove osteogenesis. No new bone formation was observed in experimental control group.

CONCLUSIONThe process of new bone formation in the distraction area is dynamic. Being stimulated primarily, the process was kept highly active till quiescence phase finally. The X-ray examination shows that there is distinctively low roentgenopeque. Nevertheless, roentgenography is so far a very effective and convenient method to evaluate and monitor the DO correction efficiency.

Animals ; Bone Morphogenetic Proteins ; biosynthesis ; metabolism ; Bone Regeneration ; Cats ; Cleft Palate ; diagnostic imaging ; metabolism ; surgery ; Osteogenesis ; Osteogenesis, Distraction ; Palate, Hard ; diagnostic imaging ; metabolism ; surgery ; Radiography ; X-Ray Film

OBJECTIVETo study the expression and distribution of bone morphogenetic protein (BMP) in newly formed bone by distraction osteogenesis (DO), and to explore the mechanism of the DO bone formation and remodeling.

METHODSThe cleft palate (CP) experimental animal models (23 Rhesus monkeys) were established surgically. In experimental group (21 Rhesus monkeys), the palatal defects were corrected by means of DO at the rhythm of 0.4 mm twice per day. The specimens were retrieved under euthanasia at 1, 2, 4, 6, 8, 12, 24 weeks intervals respectively in retention period. BMP immunohistochemical study was then performed. The blank control and experimental group (each of 2 animals) were set for comparison study.

RESULTSThe immunohistochemical study showed that BMP existed mainly in cytoplasma of osteoblasts, during the process of new bone formation. In early stage of 1 or 2 weeks, abundant osteoblasts aggregating on surfaces of the new bone trabeculae with positive DAB dye were observed. Through 4 to 6 weeks, the proliferative osteoblasts with very strong positive DAB dye indicating BMP expression were recorded. From 8 to 12 weeks, the expression of BMP and quantity of osteoblasts decreased gradually while more matured new bone structures were observed.

CONCLUSIONDuring the whole retention period, the expression of BMP showed a tendency from weak to strong and then to final cessation, this indicated a process of formation, remodeling and maturation of osteogenesis.

Animals ; Bone Morphogenetic Proteins ; metabolism ; Cleft Palate ; metabolism ; surgery ; Macaca mulatta ; Osteogenesis, Distraction

OBJECTIVETo study the ultrastructure and Ca/P element spectrometry of distraction osteogenesis (DO) for reconstruction of cleft palate (CP), so as to explore the osteogenesis and remodeling of new bone in situ.

METHODS23 rhesus macaques were operated to establish animal models of CP. 2 monkeys didn't received DO as controls. The other 21 monkeys in experimental group underwent DO to correct both bony and soft tissue defects in palate. The distraction was performed at a rate of 0.8 mm/d, twice a day until the cleft was closed. After fixation for 1, 2, 4, 6, 8, 12, 24 weeks, every 3 animals were sacrificed to get the specimens at the distraction gap. The scanning electron microscopic study and Ca, P elements spectrometric analysis were adopted. There were also two unoperated animals as sham group.

RESULTSAfter fixation for 1-2 weeks, the distraction gap was full of collagen fibers oriented along vector of distraction. Few trabeculae was seen at the margin area. After fixation for 4-6 weeks, active osteogenesis was presented with new formed bone trabeculae and abundant cellular component. After fixation for 8-12 weeks, the new formed bone became mature and couldn't distinguish from the normal bone. 24 weeks later, the bone between the distraction gap had a similar structure to the normal bone. Elements spectrometric analysis results indicated that in early stage of osteogenesis, the P and S peaks were relatively high while the Ca peak was much lower. During the late stage, the S peak was obviously decreased, and Ca/P ratio increased to normal level as in the empty control group.

CONCLUSIONSThe CP can be corrected by DO. The new bone between the distraction gap is formed and remodeled through intramembraneous osteogenesis.

Animals ; Cleft Palate ; metabolism ; pathology ; surgery ; Disease Models, Animal ; Female ; Macaca mulatta ; Male ; Microscopy, Electron, Scanning ; Osteogenesis ; Osteogenesis, Distraction ; methods ; Palate ; surgery ; ultrastructure

OBJECTIVETo investigate the osteogenesis mechanism by analysis of the expression of insulin-like growth factor-I (IGF-1) and alkaline phosphatase (ALP) in the reconstruction of cleft palate (CP) with distraction osteogenesis (DO) in rhesus.

METHODSThe CP animal models were established surgically. 21 rhesus in experimental group underwent DO to close the soft and bony defect, followed by consolidations. Every 3 animals were killed and the specimen were taken out after consolidation of 1, 2, 4, 6, 8, 12, 24 weeks. The mRNA of IGF-1 and ALP were detected with Real-time RT-PCR technique. The expression of IGF-1 and ALP was quantitatively analyzed by ELISA. The results were compared with those in control and sham groups (each of 2 animals), respectively.

RESULTSSince consolidation, the mRNA of IGF-1 and ALP increased significantly at one week and reached the peak at two weeks, but decrease to control level after 12 weeks of consolidation. The expression of IGF-1 also increased to peak level after two weeks of consolidation. The expression of ALT increased significantly since consolidation and reach the peak value after six weeks. They all decreased to nearly control level after 8-12 weeks.

CONCLUSIONSThe palate cleft can be successfully closed with new formed bone after DO. The mechanism of bone consolidation is intramembranous bone formation.

Alkaline Phosphatase ; metabolism ; Animals ; Bone Regeneration ; Cleft Palate ; metabolism ; surgery ; Insulin-Like Growth Factor I ; metabolism ; Macaca ; Osteogenesis, Distraction ; Postoperative Period

OBJECTIVETo explore the role of histone H3 acetylation in cleft palate induced by 2, 3, 7, 8-Tetrachlorodibenzo-p-dioxin (TCDD) in C57BL/6J mice, and its mechanism.

METHODSOn gestation day 10 (GD10), 36 pregnant mice were randomly divided into two groups as the treated group(n = 18) and the control group( n = 18). The mice in the treated group received intragastric administration with TCDD 28 μg/kg, while the mice in the control group received equivalent corn oil. The pregnant mice were sacrificed on GD13. 5, GD14. 5 and GD15. 5, collecting fetal palates to determine the activities of histone acetyltransferases (HATs) by Colorimetric and the expression level of acetylated histone H3 (Acetylated histone H3, Ac-H3) by Western-blot.

RESULTSThe activity of HATs was 0.409 7 ± 0.0147, 0.522 3 ± 0.017 1 and 0.643 5 ± 0.013 9 in control group on GD13.5, GD14.5 and GD15.5; 0.865 0 ± 0.0129, 0.719 1 ± 0.017 8 and 0.551 2 ± 0.016 8 in TCDD group. The activity of HATs in TCDD group was higher than that in control group on GD13. 5, GD14. 5, showing significantly difference between the two groups (t = - 56. 932, t = - 19. 516, P < 0.01); however, the activity of HATs in TCDD group was significantly lower than that in control group on GD15. 5 (t = 10. 382, P < 0.01). The expression level of Ac-H3 was 0.745 0 ± 0.113 5, 1.055 9 ± 0.249 4 and 1.795 5 ± 0.081 9 in control group on GD13. 5, GD14. 5 and GD15. 5; while 1.4490 ± 0. 1460, 1. 641 8 ± 0.099 7 and 1. 512 1 ± 0. 150 2 in TCDD group. The expression of Ac-H3 in TCDD group was higher than that in control group on GD13. 5, GD14. 5, showing significantly difference( t = -6. 593, -3. 779, P <0. 01, P <0.05) ; However, the expression of Ac-H3 in TCDD group was statistically lower than that in control group (t = 2. 870, P <0. 05).

CONCLUSIONThe acetylation of histone H3 was involved in the cleft palate of C57BL/6J mice induced by TCDD, which may be one of the mechanisms in TCDD-induced cleft palate.

Acetylation ; drug effects ; Acetyltransferases ; metabolism ; Animals ; Cleft Palate ; chemically induced ; metabolism ; Dioxins ; Female ; Fetus ; Histones ; metabolism ; Humans ; Mice ; Mice, Inbred C57BL ; Polychlorinated Dibenzodioxins ; Pregnancy ; Random Allocation ; Teratogens

The cranial neural crest plays a fundamental role in orofacial development and morphogenesis. Accordingly, mutations with impact on the cranial neural crest and its development lead to orofacial malformations such as cleft lip and palate. As a pluripotent and dynamic cell population, the cranial neural crest undergoes vast transcriptional and epigenomic alterations throughout the formation of facial structures pointing to an essential role of factors regulating chromatin state or transcription levels. Using CRISPR/Cas9-guided genome editing and conditional mutagenesis in the mouse, we here show that inactivation of Kat5 or Ep400 as the two essential enzymatic subunits of the Tip60/Ep400 chromatin remodeling complex severely affects carbohydrate and amino acid metabolism in cranial neural crest cells. The resulting decrease in protein synthesis, proliferation and survival leads to a drastic reduction of cranial neural crest cells early in fetal development and a loss of most facial structures in the absence of either protein. Following heterozygous loss of Kat5 in neural crest cells palatogenesis was impaired. These findings point to a decisive role of the Tip60/Ep400 chromatin remodeling complex in facial morphogenesis and lead us to conclude that the orofacial clefting observed in patients with heterozygous KAT5 missense mutations is at least in part due to disturbances in the cranial neural crest.
Animals ; Mice ; Chromatin Assembly and Disassembly ; Cleft Lip/genetics* ; Cleft Palate/genetics* ; DNA Helicases/metabolism* ; DNA-Binding Proteins ; Neural Crest/metabolism* ; Skull ; Transcription Factors/metabolism*

OBJECTIVETo test the changing expression level of Annexin I, cPLA(2) and PCNA in the palatine process of cleft-palate mice A/J and C57B/6j induced by dexamethasone. To discuss the developing mechanism of cleft-palate and the corresponding preventive methods.

METHODs Pregnant mice A/J and C57BL/6j were randomly divided into normal group as blank control, group with deformity induced by dexamethasone, group given VitB(12) as antagonist to deforming factor, group given only VitB(12). The relative quantity of Annexin I, Cpla2 and PCNA were detected by immunoblotting.

RESULTSAmong mice A/J, with the development of palatine process, Annexin I's expression level was increased in the normal group, and other groups showed the similar changes. Annexin I's expression level was significantly higher in group DEX and group DEX + VitB(12) than in normal group and VitB(12) group of, while there was no significant difference between normal group and VitB(12) group. But the changes of cPLA(2) and PCNA expression level was in an opposite direction, with development it decreased in the normal mice's palatine process. In mice C57B/6j there was no significant difference between normal group and group DEX on the measured quantity of Annexin I, cPLA(2) and

CONCLUSIONSAnnexin I and cPLA(2) introduce glucocorticoid to induce cleft-palate. VitB(12) can not inhibit DEX's enhancing effect on the expression level of Annexin I, but it can antagonize DEX's inhibiting effect on expression level of cPLA(2), which is probably one of the mechanisms why VitB(12) antagonize glucocorticoid's deforming effect.

Abnormalities, Drug-Induced ; etiology ; Animals ; Annexin A1 ; biosynthesis ; Cleft Palate ; chemically induced ; Dexamethasone ; toxicity ; Female ; Male ; Mice ; Mice, Inbred C57BL ; Palate ; embryology ; metabolism ; Phospholipases A ; biosynthesis ; Pregnancy ; Proliferating Cell Nuclear Antigen ; biosynthesis ; Random Allocation

OBJECTIVETo investigate the morphologic changes of embryonic palatal development exposed to retinoic acid (RA) in mouse, and to detect the significance of the expression of TGFbeta1, TGFbeta3, EGF and BCL2.

METHODSThe stage of palatal development was examined by light microscopy. S-P immunohistochemistry and in-situ hybridization was used to detect spatio-temporal patterns of expression of TGFbeta1, TGFbeta3, EGF and BCL2 in embryonic palate.

RESULTSThe fetus exposed to RA resulted in formation of small palatal shelves without contact and fusion of each other to form and intact palate. RA can regulate the embryonic palatal expression of genes involved in RA-induced cleft palate.

CONCLUSIONSRA can inhibit the proliferation of MEPM cell to form small palatal shelves and induce abnormal differentiation of MEE cell causing the bi-palatal shelves no contact and fuse with each other, then induce the formation of cleft palate. RA can regulate the spatio-temporal patterns of expression of TGFbeta1, TGFbeta3 and EGF in embryonic palatal processes and the change of special expression of these genes in embryonic palatal processes are involved in RA-induced cleft palate.

Abnormalities, Drug-Induced ; etiology ; Animals ; Cleft Palate ; chemically induced ; embryology ; Embryo, Mammalian ; Epidermal Growth Factor ; biosynthesis ; Female ; Mice ; Mice, Inbred C57BL ; Palate ; embryology ; metabolism ; Transforming Growth Factor beta ; biosynthesis ; Tretinoin ; toxicity