FGF signalling and SUMO modification: new players in the aetiology of cleft lip and/or palate

Single-cell transcriptome and chromatin accessibility mapping of upper lip and primary palate fusion

Cleft lip and/or primary palate (CL/P) represent a prevalent congenital malformation, the aetiology of which is highly intricate. Although it is generally accepted that the condition arises from failed fusion between the upper lip and primary palate, the precise mechanism underlying this fusion process remains enigmatic. In this study, we utilized transposase-accessible chromatin sequencing (scATAC-seq) and single-cell RNA sequencing (scRNA-seq) to interrogate lambdoidal junction tissue derived from C57BL/6J mouse embryos at critical stages of embryogenesis (10.5, 11.5 and 12.5 embryonic days). We successfully identified distinct subgroups of mesenchymal and ectodermal cells involved in the fusion process and characterized their unique transcriptional profiles. Furthermore, we conducted cell differentiation trajectory analysis, revealing a dynamic repertoire of genes that are sequentially activated or repressed during pseudotime, facilitating the transition of relevant cell types. Additionally, we employed scATAC data to identify key genes associated with the fusion process and demonstrated differential chromatin accessibility across major cell types. Finally, we constructed a dynamic intercellular communication network and predicted upstream transcriptional regulators of critical genes involved in important signalling pathways. Our findings provide a valuable resource for future studies on upper lip and primary palate development, as well as congenital defects.

DNA methylation profile of lip tissue from congenital nonsyndromic cleft lip and palate patients by whole-genome bisulfite sequencing

Congenital nonsyndromic cleft lip and palate (NSCLP) is one of the most common malformations worldwide. DNA methylation has been implicated in many diseases. However, its involvement in lip tissue from NSCLP is not well understood. This study aimed to investigate the role of dysregulated DNA methylation in NSCLP. DNA methylation profile was determined in eight injured and five self-normal lip tissue samples from children with NSCLP by whole-genome bisulfite sequencing. A total of 2,711 differentially methylated regions (DMRs), corresponding to 1,231 genes were identified. Given the important role of promoter methylation in regulating gene expression, the promoter DMR-related genes were considered. Bioinformatics analysis demonstrated that some of them showed potential associations with NSCLP. Therefore, the well-known NSCLP susceptibility gene, GLI family zinc finger 2 (GLI2) with an unknown role in its DNA methylation in NSCLP, was selected for further analysis. The promoter hypomethylation and higher mRNA expression level of GLI2 were observed in injured lip tissues by verification in additional samples. Moreover, dual luciferase reporter assay indicated that promoter hypermethylation of GLI2 inhibited its transcription. Overall, this study suggested that abnormal DNA methylation in lip tissue may be correlated with the pathogenesis of congenital NSCLP.

SUMOylation in Skeletal Development, Homeostasis, and Disease

The modification of proteins by small ubiquitin-related modifier (SUMO) molecules, SUMOylation, is a key post-translational modification involved in a variety of biological processes, such as chromosome organization, DNA replication and repair, transcription, nuclear transport, and cell signaling transduction. In recent years, emerging evidence has shown that SUMOylation regulates the development and homeostasis of the skeletal system, with its dysregulation causing skeletal diseases, suggesting that SUMOylation pathways may serve as a promising therapeutic target. In this review, we summarize the current understanding of the molecular mechanisms by which SUMOylation pathways regulate skeletal cells in physiological and disease contexts.

Identification of microRNAs and gene regulatory networks in cleft lip common in humans and mice

The etiology of cleft lip with/without cleft palate (CL/P), one of the most frequent craniofacial birth defects worldwide, is complicated by contributions of both genetic and environmental factors. Understanding the etiology of these conditions is essential for developing preventive strategies. This study thus aims to identify regulatory networks of microRNAs (miRNAs), transcriptional factors (TFs) and non-TF genes associated with cleft lip (CL) that are conserved in humans and mice. Notably, we found that miR-27b, miR-133b, miR-205, miR-376b and miR-376c were involved in the regulation of CL-associated gene expression in both humans and mice. Among the candidate miRNAs, the overexpression of miR-27b, miR-133b and miR-205, but not miR-376b and miR-376c, significantly inhibited cell proliferation through suppression of CL-associated genes (miR-27b suppressed PAX9 and RARA; miR-133b suppressed FGFR1, PAX7, and SUMO1; and miR-205 suppressed PAX9 and RARA) in cultured human and mouse lip mesenchymal cells. Taken together, our results suggest that elevated expression of miR-27b, miR-133b and miR-205 may play a crucial role in CL through the suppression of genes associated with CL.

Extracellular Matrix Composition and Remodeling: Current Perspectives on Secondary Palate Formation, Cleft Lip/Palate, and Palatal Reconstruction

Craniofacial development comprises a complex process in humans in which failures or disturbances frequently lead to congenital anomalies. Cleft lip with/without palate (CL/P) is a common congenital anomaly that occurs due to variations in craniofacial development genes, and may occur as part of a syndrome, or more commonly in isolated forms (non-syndromic). The etiology of CL/P is multifactorial with genes, environmental factors, and their potential interactions contributing to the condition. Rehabilitation of CL/P patients requires a multidisciplinary team to perform the multiple surgical, dental, and psychological interventions required throughout the patient's life. Despite progress, lip/palatal reconstruction is still a major treatment challenge. Genetic mutations and polymorphisms in several genes, including extracellular matrix (ECM) genes, soluble factors, and enzymes responsible for ECM remodeling (e.g., metalloproteinases), have been suggested to play a role in the etiology of CL/P; hence, these may be considered likely targets for the development of new preventive and/or therapeutic strategies. In this context, investigations are being conducted on new therapeutic approaches based on tissue bioengineering, associating stem cells with biomaterials, signaling molecules, and innovative technologies. In this review, we discuss the role of genes involved in ECM composition and remodeling during secondary palate formation and pathogenesis and genetic etiology of CL/P. We also discuss potential therapeutic approaches using bioactive molecules and principles of tissue bioengineering for state-of-the-art CL/P repair and palatal reconstruction.

Two novel genes TOX3 and COL21A1 in large extended Malay families with nonsyndromic cleft lip and/or palate

BACKGROUND

Nonsyndromic cleft lip and/or palate is one of the most common human birth defects worldwide that affects the lip and/or palate. The incidence of clefts varies among populations through ethnic, race, or geographical differences. The focus on Malay nonsyndromic cleft lip and/or palate (NSCL/P) is because of a scarce report on genetic study in relation to this deformity in Malaysia. We are interested to discuss about the genes that are susceptible to cause orofacial cleft formation in the family.

METHODS

Genome-wide linkage analysis was carried out on eight large extended families of NSCL/P with the total of 91 individuals among Malay population using microarray platform. Based on linkage analyses findings, copy number variation (CNV) of LPHN2, SATB2, PVRL3, COL21A1, and TOX3 were identified in four large extended families that showed linkage evidence using quantitative polymerase chain reaction (qPCR) as for a validation purpose. Copy number calculated (CNC) for each genes were determined with Applied Biosystems CopyCallerTM Software v2.0. Normal CNC of the target sequence expected was set at two.

RESULTS

Genome-wide linkage analysis had discovered several genes including TOX3 and COL21A1 in four different loci 4p15.2-p16.1, 6p11.2-p12.3, 14q13-q21, and 16q12.1. There was significant decreased, p < 0.05 of SATB2, COL21A1, and TOX3 copy number in extended families compared to the normal controls.

CONCLUSION

Novel linkage evidence and significant low copy number of COL21A1 and TOX3 in NSCLP family was confirmed. These genes increased the risks toward NSCLP formation in that family traits.

Developing Practical Therapeutic Strategies that Target Protein SUMOylation

Post-translational modification by small ubiquitin-like modifier (SUMO) has emerged as a global mechanism for the control and integration of a wide variety of biological processes through the regulation of protein activity, stability and intracellular localization. As SUMOylation is examined in greater detail, it has become clear that the process is at the root of several pathologies including heart, endocrine, and inflammatory disease, and various types of cancer. Moreover, it is certain that perturbation of this process, either globally or of a specific protein, accounts for many instances of congenital birth defects. In order to be successful, practical strategies to ameliorate conditions due to disruptions in this post-translational modification will need to consider the multiple components of the SUMOylation machinery and the extraordinary number of proteins that undergo this modification.

Gene-gene interaction between MSX1 and TP63 in Asian case-parent trios with nonsyndromic cleft lip with or without cleft palate

BACKGROUND

Small ubiquitin-like modification, also known as sumoylation, is a crucial post-translational regulatory mechanisms involved in development of the lip and palate. Recent studies reported two sumoylation target genes, MSX1 and TP63, to have achieved genome-wide level significance in tests of association with nonsyndromic clefts. Here, we performed a candidate gene analysis considering gene-gene and gene-environment interaction for SUMO1, MSX1, and TP63 to further explore the etiology of nonsyndromic cleft lip with or without cleft palate (NSCL/P).

METHODS

A total of 130 single-nucleotide polymorphisms (SNPs) in or near SUMO1, MSX1, and TP63 was analyzed among 1,038 Asian NSCL/P trios ascertained through an international consortium. Conditional logistic regression models were used to explore gene-gene (G × G) and gene-environment (G × E) interaction involving maternal environmental tobacco smoke and multivitamin supplementation. Bonferroni correction was used for G × E analysis and permutation tests were used for G × G analysis.

RESULTS

While transmission disequilibrium tests and gene-environment interaction analysis showed no significant results, we did find signals of gene-gene interaction between SNPs near MSX1 and TP63. Three pairwise interactions yielded significant p values in permutation tests (rs884690 and rs9290890 with p = 9.34 × 10^-5 and empirical p = 1.00 × 10^-4 , rs1022136 and rs4687098 with p = 2.41 × 10^-4 and empirical p = 2.95 × 10^-4 , rs6819546 and rs9681004 with p = 5.15 × 10^-4 and empirical p = 3.02 × 10^-4 ).

CONCLUSION

Gene-gene interaction between MSX1 and TP63 may influence the risk of NSCL/P in Asian populations. Our study provided additional understanding of the genetic etiology of NSCL/P and underlined the importance of considering gene-gene interaction in the etiology of this common craniofacial malformation.

Polymorphic variants in VAX1 and the risk of nonsyndromic cleft lip with or without cleft palate in a population from northern China

BACKGROUND

Nonsyndromic cleft lip with or without cleft palate (NSCL/P) is one of the most common craniofacial birth defects, and the etiology of NSCL/P involves both genetic and environmental factors. Genome-wide association study (GWAS) identified a novel susceptibility locus of ventral anterior homeobox 1 (VAX1) in patients with NSCL/P. However, the association of single nucleotide polymorphisms (SNPs) of VAX1 with NSCL/P is inconclusive due to the differences in the racial and ethnic populations. The aim of this study was to replicate the association between VAX1 and NSCL/P in a northern Chinese Han population.

METHODS

Our study included 186 patients with NSCL/P and 223 healthy individuals from northern China. Five SNPs (rs4752028, rs10787760, rs7078160, rs6585429, and rs1871345) on VAX1 were genotyped using the SNaPshot method.

RESULTS

Recessive genetic model analysis revealed that homozygous genotype CC of VAX1 rs4752028 was associated with an increased risk of NSCL/P (odds ratio = 1.89, 95% confidence interval = 1.12-3.19, P = 0.017), but the results were not significant after the Bonferroni correction for multiple comparisons. The allele and genotype frequencies of rs10787760, rs7078160, rs6585429, and rs1871345 and the allele frequencies of rs4752028 showed no significant differences between cases and controls. Haplotype and SNP-SNP interaction analyses did not detect any significant association of VAX1 with the occurrence of NSCL/P.

CONCLUSION

VAX1 rs4752028 was weakly associated with NSCL/P development in the studied northern Chinese Han population.

Genome-wide analyses of non-syndromic cleft lip with palate identify 14 novel loci and genetic heterogeneity

Non-syndromic cleft lip with palate (NSCLP) is the most serious sub-phenotype of non-syndromic orofacial clefts (NSOFC), which are the most common craniofacial birth defects in humans. Here we conduct a GWAS of NSCLP with multiple independent replications, totalling 7,404 NSOFC cases and 16,059 controls from several ethnicities, to identify new NSCLP risk loci, and explore the genetic heterogeneity between sub-phenotypes of NSOFC. We identify 41 SNPs within 26 loci that achieve genome-wide significance, 14 of which are novel (RAD54B, TMEM19, KRT18, WNT9B, GSC/DICER1, PTCH1, RPS26, OFCC1/TFAP2A, TAF1B, FGF10, MSX1, LINC00640, FGFR1 and SPRY1). These 26 loci collectively account for 10.94% of the heritability for NSCLP in Chinese population. We find evidence of genetic heterogeneity between the sub-phenotypes of NSOFC and among different populations. This study substantially increases the number of genetic susceptibility loci for NSCLP and provides important insights into the genetic aetiology of this common craniofacial malformation.

Non-syndromic cleft lip with palate is a common birth defect of unknown aetiology. Here, the authors discover 14 new genes associated with this condition, and show genetic heterogeneity in this and other non-syndromic orofacial clefting disorders.

Sumoylation in Craniofacial Disorders

Craniofacial development requires a complex series of coordinated and finely tuned events to take place, during a relatively short time frame. These events are set in motion by switching on and off transcriptional cascades that involve the use of numerous signalling pathways and a multitude of factors that act at the site of gene transcription. It is now well known that amidst the subtlety of this process lies the intricate world of protein modification, and the posttranslational addition of the small ubiquitin -like modifier, SUMO, is an example that has been implicated in this process. Many proteins that are required for formation of various structures in the embryonic head and face adapt specific functions with SUMO modification. Interestingly, the main clinical phenotype reported for a disruption of the SUMO1 locus is the common birth defect cleft lip and palate. In this chapter therefore, we discuss the role of SUMO1 in craniofacial development, with emphasis on orofacial clefts. We suggest that these defects can be a sensitive indication of down regulated SUMO modification at a critical stage during embryogenesis. As well as specific mutations affecting the ability of particular proteins to be sumoylated, non-genetic events may have the effect of down-regulating the SUMO pathway to give the same result. Enzymes regulating the SUMO pathway may become important therapeutic targets in the preventative and treatment therapies for craniofacial defects in the future.

Associations between microRNA binding site SNPs in FGFs and FGFRs and the risk of non-syndromic orofacial cleft

We hypothesized that microRNA binding site single nucleotide polymorphisms (SNPs) in fibroblast growth factors (FGFs) and their receptor genes (FGFRs) may affect microRNA and mRNA interactions and are thereby associated with susceptibility of non-syndromic orofacial cleft (NSOC). Ten SNPs among the FGF and FGFR genes were selected and their associations with NSOC susceptibility were investigated in a case-control study of 602 patients with NSOC and 605 healthy controls. FGF2/rs1048201, FGF5/rs3733336 and FGF9/rs546782 showed suggestive association with NSOC susceptibility. In the combination analysis, the observed odds ratios (ORs) decreased with the number of protective alleles (rs1048201-T, rs3733336-G and rs546782-T) but were not statistically significant beyond the first comparison. Hsa-miRNA-496, hsa-miRNA-145 and hsa-miRNA-187 were predicted to be miRNAs with binding sites within/near these SNPs and were expressed in lip tissues. Decreased FGF2, FGF5 and FGF9 expression was observed in three cell lines transfected with the corresponding miRNAs. Moreover, the three SNPs could contribute to differential binding efficacy between hsa-miRNA-496 and FGF2, hsa-miRNA-145 and FGF5, hsa-miRNA-187 and FGF9 in luciferase assay. The results suggest that FGF2/rs1048201, FGF5/rs3733336 and FGF9/rs546782 are associated with the risk of NSOC and that these miRNA-FGF interactions may affect NSOC development.

Post-translational Modifications in Heart Failure: Small Changes, Big Impact

Heart failure is a complex disease process with various aetiologies and is a significant cause of morbidity and death world-wide. Post-translational modifications (PTMs) alter protein structure and provide functional diversity in terms of physiological functions of the heart. In addition, alterations in protein PTMs have been implicated in human disease pathogenesis. Small ubiquitin-like modifier mediated modification (SUMOylation) pathway was found to play essential roles in cardiac development and function. Abnormal SUMOylation has emerged as a new feature of heart failure pathology. In this review, we will highlight the importance of SUMOylation as a regulatory mechanism of SERCA2a function, and its therapeutic potential for the treatment of heart failure.

Pathogenesis of POLR1C-dependent Type 3 Treacher Collins Syndrome revealed by a zebrafish model

Treacher Collins Syndrome (TCS) is a rare congenital birth disorder (1 in 50,000 live births) characterized by severe craniofacial defects, including the downward slanting palpebral fissures, hypoplasia of the facial bones, and cleft palate (CP). Over 90% of patients with TCS have a mutation in the TCOF1 gene. However, some patients exhibit mutations in two new causative genes, POLR1C and POLR1D, which encode subunits of RNA polymerases I and III, that affect ribosome biogenesis. In this study, we examine the role of POLR1C in TCS using zebrafish as a model system. Our data confirmed that polr1c is highly expressed in the facial region, and dysfunction of this gene by knockdown or knock-out resulted in mis-expression of neural crest cells during early development that leads to TCS phenotype. Next generation sequencing and bioinformatics analysis of the polr1c mutants further demonstrated the up-regulated p53 pathway and predicted skeletal disorders. Lastly, we partially rescued the TCS facial phenotype in the background of p53 mutants, which supported the hypothesis that POLR1C-dependent type 3 TCS is associated with the p53 pathway.

Association between NOGGIN and SPRY2 polymorphisms and nonsyndromic cleft lip with or without cleft palate

Nonsyndromic cleft lip with or without cleft palate (NSCLP) is a common congenital malformation with a worldwide prevalence rate of 0.4-2.0% among live births, depending on race and ethnic background. Single-nucleotide polymorphisms (SNPs) of genes may contribute to NSCLP risk, although the risk factors and pathogenesis of NSCLP remain unknown. The objective of this study was to investigate association of SNPs of noggin (NOG) and sprouty homolog 2 (SPRY2) with NSCLP risk. A total of 188 NSCLP patients and 228 healthy controls from northern China were recruited for genotyping of these SNPs using the SNaP shot method. The frequency of the NOG rs227731 genotype was significantly lower among NSCLP cases than among controls. Logistic regression analysis showed rs227731 CC genotype was associated with decreased NSCLP susceptibility (OR = 0.31, 95% CI = 0.12-0.80) compared to the AA homozygote. However, no association between SPRY2, SNPs, and NSCLP risk were observed in this cohort of patients. In conclusion, NOG rs227731 genotype was associated with decreased NSCLP risk in a Northern Chinese population.

Role of angiogenesis-related genes in cleft lip/palate: review of the literature

OBJECTIVES

Cleft lip and cleft palate (CLP) are the most common congenital craniofacial anomalies. They have a multifactorial etiology and result from an incomplete fusion of the facial buds. Two main mechanisms, acting alone or interacting with each other, were evidenced in this fusion defect responsible for CLP: defective tissue development and/or defective apoptosis in normal or defective tissues. The objective of this work was to study the implication and role of angiogenesis-related genes in the etiology of CL/P.

METHODS

Our methodological approach included a systematic and thorough analysis of the genes involved in CL/P (syndromic and non-syndromic forms) including previously identified genes but also genes that could potentially be angiogenesis-related (OMIM, Pub Med).We studied the interactions of these different genes and their relationships with potential environmental factors.

RESULTS

TGFβ, FGA, PDGFc, PDGFRa, FGF, FGFR1, FGFR2 growth factors as well as MMP and TIMP2 proteolytic enzymes are involved in the genesis of CLP (P>L). Furthermore, 18 genes involved in CLP also interact with angiogenesis-related genes.

DISCUSSION

Even if the main angiogenesis-related genes involved in CLP formation are genes participating in several biological activities and their implication might not be always related to angiogenesis defects, they nevertheless remain an undeniably important research pathway. Furthermore, their interactions with environmental factors make them good candidates in the field of CLP prevention.

Association of JARID2 polymorphisms with non-syndromic orofacial clefts in northern Chinese Han population

OBJECTIVES

Non-syndromic orofacial clefts (NSOC) are the most common human craniofacial malformation in all worldwide populations. Recently, the jumoji AT-rich interaction domain 2 (JARID2) had been reported to be a novel candidate gene for non-syndromic cleft lip with or without cleft palate (CL/P). The SNPs rs2076056, rs2237138 and rs2299043 in JARID2 were highly significant in Italian families.

MATERIAL AND METHODS

In the current research, a case-control study was conducted to examine the association between these three SNPs and NSOC in a northern Chinese Han population. Genotyping of the three SNPs were performed using SNaPshot minisequencing technique.

RESULTS

Distribution of rs2237138 genotypes in CL/P group was different from those in the control group (P = 0.04), but significant results did not persist after Benjamini and Hochberg false discovery rate (FDR) correction for multiple tests. Further logistic regression analysis showed that rs2237138 GG genotypes were associated with decreased CL/P susceptibility (OR = 0.34, 95% CI = 0.13-0.84), compared with the AA wild-type homozygote. For the haplotype CGT, a statistically difference was identified between the CL/P group and controls (P = 0.04). And carriers of GAT haplotype were considered to be less frequent among cleft palate only group as compared to controls (P = 0.02). However, both of the haplotypes association did not remain statistically significant after Benjamini and Hochberg FDR correction.

CONCLUSION

We got a weak association between these polymorphisms and NSOC in both single-marker and haplotype analyses. Our data further strengthen the conclusion that JARID2 polymorphisms are associated with NSOC susceptibility.

Investigation of FGF1 and FGFR gene polymorphisms in a group of Iranian patients with nonsyndromic cleft lip with or without cleft palate

OBJECTIVE

Nonsyndromic cleft lip with or without cleft palate (NS-CL/P) is one of the most common craniofacial malformations determined by the interaction between multiple genes and environmental risk factors. Genes coding for fibroblast growth factors and their receptors (FGF/FGFR genes) are considered as excellent candidate genes, which their proteins play important roles in craniofacial and palatal development. The aim of the current study was to assess the possible association between FGF1 rs34010 C>A and FGFR1 rs13317 A>G gene polymorphisms and susceptibility to NS-CL/P in an Iranian population.

DESIGN

This case-control retrospective study was performed on a total of 200 subjects including 100 NS-CL/P patients and 100 healthy unrelated controls. Tetra amplification refractory mutation system-polymerase chain reaction (T-ARMS-PCR) was used to detect FGF1 rs34010 C>A and FGFR1 rs13317 A>G SNPs.

RESULTS

Our data demonstrated that the FGF1 rs34010, CA and CA+AA genotypes were associated with a reduced risk of NS-CL/P the in codominant (CA vs. CC: OR=0.29, 95%CI=0.16-0.55, P=0.001) and dominant (CA+AA vs. CC: OR=0.36, 95%CI=0.19-0.69, P=0.001) tested inheritance models, respectively. Additionally, the analysis of FGF1/FGFR1 genotype combinations revealed that rs34010CA/rs13317AA and rs34010CA/rs13317AG combinations were associated with a lower risk of NS-CL/P (OR=0.357, P=0.008 for the rs34010CA/rs13317AA; OR=0.226, P=0.004 for the rs34010CA/rs13317AG).

CONCLUSIONS

Our findings suggest that the FGF1 rs34010 C/A polymorphism was associated with a decreased risk of NS-CL/P, and might act as a protective factor against NS-CL/P predisposition.

Skin Tissue Surface Morphology and Quality of RNA and Protein Extracted from Fresh and Stabilized Human Cleft Lip and Palate Tissue

Cleft lip palate is a human congenital disorder worldwide and the study of this genetic disease requires molecular genetic analysis. This analysis required the use of nucleic acid and protein, thus good quality and quantity of its extraction is important. We are comparing RNA and protein extractions from tissue biopsy of cleft lip palate in both fresh and stabilized condition. Tissue morphology was also captured using Scanning Electron Microscopy (SEM) for any morphology differences. Tissue homogenization may destroy nucleic acid stability but not its morphology. Low RNA concentration from stabilized tissue was found. However, there was no crucial issue of protein extraction, degradation or concentration. Tissue morphology was slight different between normal and CL/P tissue.

TGFA and IRF6 contribute to the risk of nonsyndromic cleft lip with or without cleft palate in northeast China

Nonsyndromic cleft lip with or without cleft palate (NSCL/P) are common birth defects with a complex etiology. Multiple interacting loci and possible environmental factors influence the risk of NSCL/P. 12 single nucleotide polymorphisms (SNPs) in 7 candidate genes were tested using an allele-specific primer extension for case-control and case-parent analyses in northeast China in 236 unrelated patients, 185 mothers and 154 fathers, including 128 complete trios, and 400 control individuals. TGFA and IRF6 genes showed a significant association with NSCL/P. In IRF6, statistical evidence of an association between rs2235371 (p = 0.003), rs2013162 (p<0.0001) and NSCL/P was observed in case-control analyses. Family based association tests (FBATs) showed over-transmission of the C allele at the rs2235371 polymorphism (p = 0.007). In TGFA, associations between rs3771494, rs3771523 (G3822A), rs11466285 (T3851C) and NSCL/P were observed in case-control and FBAT analyses. Associations between other genes (BCL3, TGFB3, MTHFR, PVRL1 and SUMO1) and NSCL/P were not detected.

Sumoylation regulates nuclear localization and function of zinc finger transcription factor ZIC3

ZIC3, an X-linked zinc finger transcription factor, was the first identified gene involved in establishing normal left-right patterning in humans. Mutations in the Zic3 gene in patients cause heterotaxy, which includes congenital heart defects. However, very little is known about how the function of the ZIC3 protein is regulated. Sumoylation is a posttranslational modification process in which a group of small ubiquitin-like modifier (SUMO) proteins is covalently attached to targets via a series of enzymatic reactions. Here, we report for the first time that sumoylation targets human ZIC3 primarily on the consensus lysine residue K248, which is critical for the nuclear retention of ZIC3. Consequently, SUMO modification potentiates the repressive activity of ZIC3 on the promoter of its target gene cardiac α-actin, and the mutation of lysine 248 to arginine (K248R) abolishes its repressive function. We further revealed that ZIC3 variants with mutations found in human patients with congenital anomalies exhibit aberrant sumoylation activity, which at least partially accounts for their cytoplasmic diffusion. Improved sumoylation of human disease-associated ZIC3 variants reestablishes their nuclear occupancy in the presence of SUMO E3 ligase and SUMO-1. Thus, the altered sumoylation status of ZIC3 underpins the developmental abnormalities associated with these ZIC3 mutants. The SUMO targeting consensus sequence in ZIC3 is highly conserved in its paralogs and orthologs, pointing to sumoylation as a general mechanism underlying the functional control of ZIC proteins. This study provides a potential therapeutic strategy to regain the normal subcellular distribution and function of ZIC3 mutants by restoring SUMO conjugation.

Overexpression of mouse TTF-2 gene causes cleft palate

In humans, mutations of the gene encoding for thyroid transcription factor-2 (TTF-2 or FOXE1) result in Bamforth syndrome. Bamforth syndrome is characterized by agenesis, cleft palate, spiky hair and choanal atresia. TTF-2 null mice (TTF-2^−/−) also exhibit cleft palate, suggesting its involvement in the palatogenesis. However, the molecular pathology and genetic regulation by TTF2 remain largely unknown. In the present study, the recombinant expression vector pBROAD3-TTF-2 containing the promoter of the mouse ROSA26 gene was created to form the structural gene of mouse TTF-2 and was microinjected into the male pronuclei of fertilized ova. Sequence analysis confirmed that the TTF-2 transgenic mouse model was established successfully. The transgenic mice displayed a phenotype of cleft palate. In addition, we found that TTF-2 was highly expressed in the medial edge epithelium (MEE) from the embryonic day 12.5 (E12.5) to E14.5 in TTF-2 transgenic mice. These observations suggest that overexpression of TTF-2 during palatogenesis may contribute to formation of cleft palate.

Fgf8 dosage determines midfacial integration and polarity within the nasal and optic capsules

Craniofacial development requires an exquisitely timed and positioned cross-talk between the embryonic cephalic epithelia and mesenchyme. This cross-talk underlies the precise translation of patterning processes and information into distinct, appropriate skeletal morphologies. The molecular and cellular dialogue includes communication via secreted signaling molecules, including Fgf8, and effectors of their interpretation. Herein, we use genetic attenuation of Fgf8 in mice and perform gain-of-function mouse-chick chimeric experiments to demonstrate that significant character states of the frontonasal and optic skeletons are dependent on Fgf8. Notably, we show that the normal orientation and polarity of the nasal capsules and their developing primordia are dependent on Fgf8. We further demonstrate that Fgf8 is required for midfacial integration, and provide evidence for a role for Fgf8 in optic capsular development. Taken together, our data highlight Fgf8 signaling in craniofacial development as a plausible target for evolutionary selective pressures.

Coordinated events: FGF signaling and other related pathways in palatogenesis

Cleft palate is a common craniofacial anomaly that is costly to both patients and the health care system. Investigation of each stage of palate development enhances understanding of this anomaly. Although the exact molecular signaling mechanisms that contribute to palatogenesis remain elusive, multiple pathways, such as fibroblast growth factor (FGF) signaling, have been recognized as important contributors. Alterations in FGF signaling have previously been implicated in palatal clefting. The current review discusses FGF signaling and the major signaling mediators affecting FGF signaling during each stage of palatogenesis.

Enhanced desumoylation in murine hearts by overexpressed SENP2 leads to congenital heart defects and cardiac dysfunction

Sumoylation is a posttranslational modification implicated in a variety of cellular activities, and its role in a number of human pathogeneses such as cleft lip/palate has been well documented. However, the importance of the SUMO conjugation pathway in cardiac development and functional disorders is newly emerging. We previously reported that knockout of SUMO-1 in mice led to congenital heart diseases (CHDs). To further investigate the effects of imbalanced SUMO conjugation on heart development and function and its underlying mechanisms, we generated transgenic (Tg) mice with cardiac-specific expression of SENP2, a SUMO-specific protease that deconjugates sumoylated proteins, to evaluate the impact of desumoylation on heart development and function. Overexpression of SENP2 resulted in premature death of mice with CHDs-atrial septal defects (ASDs) and/or ventricular septal defects (VSDs). Immunobiochemistry revealed diminished cardiomyocyte proliferation in SENP2-Tg mouse hearts compared with that in wild type (WT) hearts. Surviving SENP2-Tg mice showed growth retardation, and developed cardiomyopathy with impaired cardiac function with aging. Cardiac-specific overexpression of the SUMO-1 transgene reduced the incidence of cardiac structural phenotypes in the sumoylation defective mice. Moreover, cardiac overexpression of SENP2 in the mice with Nkx2.5 haploinsufficiency promoted embryonic lethality and severity of CHDs, indicating the functional interaction between SENP2 and Nkx2.5 in vivo. Our findings indicate the indispensability of a balanced SUMO pathway for proper cardiac development and function. This article is part of a Special Issue entitled 'Post-translational Modification SI'.

Cardiac function and disease: emerging role of small ubiquitin-related modifier

Small ubiquitin-related modifiers, or SUMOs, have emerged as versatile regulators of many biological functions that do so by covalent attachment to a variety of substrates via enzymatic reactions. SUMO conjugation has also been shown to be involved in a number of human pathogenic processes. More recent advances in the SUMO field have indicated a potential role for SUMO conjugation pathway in cardiogenesis. This advanced review will describe the basic features of the SUMO conjugation pathway and will summarize the most recent studies implicating the influence of the sumoylation pathway in cardiac function under both physiological and pathological conditions. WIREs Syst Biol Med 2011 3 446-457 DOI: 10.1002/wsbm.130

Genetics of nonsyndromic orofacial clefts

With an average worldwide prevalence of approximately 1.2/1000 live births, orofacial clefts are the most common craniofacial birth defects in humans. Like other complex disorders, these birth defects are thought to result from the complex interplay of multiple genes and environmental factors. Significant progress in the identification of underlying genes and pathways has benefited from large populations available for study, increased international collaboration, rapid advances in genotyping technology, and major improvements in analytic approaches. Here we review recent advances in genetic epidemiological approaches to complex traits and their applications to studies of nonsyndromic orofacial clefts. Our main aim is to bring together a discussion of new and previously identified candidate genes to create a more cohesive picture of interacting pathways that shape the human craniofacial region. In future directions, we highlight the need to search for copy number variants that affect gene dosage and rare variants that are possibly associated with a higher disease penetrance. In addition, sequencing of protein-coding regions in candidate genes and screening for genetic variation in noncoding regulatory elements will help advance this important area of research.

Variation in FGF1, FOXE1, and TIMP2 genes is associated with nonsyndromic cleft lip with or without cleft palate

BACKGROUND

Nonsyndromic cleft lip with or without cleft palate (CL/P) is a common complex birth defect caused by the interaction between multiple genes and environmental factors.

METHODS

Five hundred and eighty-seven single nucleotide polymorphisms in 40 candidate genes related to orofacial clefting were tested for association with CL/P in a clefting sample composed of 300 patients and 606 controls from Estonian, Latvian, and Lithuanian populations.

RESULTS

In case-control comparisons, the minor alleles of FGF1 rs34010 (p = 4.56 × 10(-4) ), WNT9B rs4968282 (p = 0.0013), and FOXE1 rs7860144 (p = 0.0021) were associated with a decreased risk of CL/P. Multiple haplotypes in FGF1, FOXE1, and TIMP2 and haplotypes in WNT9B, PVRL2, and LHX8 were associated with CL/P. The strongest association was found for protective haplotype rs250092/rs34010 GT in the FGF1 gene (p = 5.01 × 10(-4) ). The strongest epistatic interaction was observed between the COL2A1 and WNT3 genes.

CONCLUSIONS

Our results provide for the first time evidence implicating FGF1 in the occurrence of CL/P, and support TIMP2 and WNT9B as novel loci predisposing to CL/P. We have also replicated recently reported significant associations between variants in or near FOXE1 and CL/P. It is likely that variation in FOXE1, TIMP2, and the FGF and Wnt signaling pathway genes confers susceptibility to nonsyndromic CL/P in Northeastern European populations.

TBX22 mutation associated with cleft lip/palate, hypodontia, and limb anomaly

Mutations in TBX22 are known causes of cleft palate with/without ankyloglossia. We identified a hemizygous missense c.452G>T (p.Arg151Leu) mutation in a Thai boy who had unilateral complete cleft lip and palate, agenesis of a maxillary second premolar, ankyloglossia, hypoplastic carpal bones, and hypoplastic right thumb. Our study has demonstrated that TBX22 mutation is associated not only with cleft palate and ankyloglossia, but also cleft lip and palate and tooth agenesis. Phenotypic variability caused by a single nucleotide substitution is clearly demonstrated.

Fetal genetic risk of isolated cleft lip only versus isolated cleft lip and palate: a subphenotype analysis using two population-based studies of orofacial clefts in Scandinavia

Background

Cleft lip only (CLO) and cleft lip and palate (CLP) are commonly regarded as variants of the same defect and traditionally combined to form the single group of cleft lip with or without cleft palate (CL/P) prior to analysis. However, recent data have suggested that at least a subgroup of isolated CLO may be etiologically distinct from isolated CLP.

Methods

To explore fetal genetic risk of isolated CLO separately from isolated CLP, we performed a sub-phenotype analysis using two population-based studies of clefts in Scandinavia. One hundred and twenty-one isolated CLO, 190 isolated CLP, and 592 control triads were available from Norway(1996–2001), and a further 76 isolated CLO and 107 isolated CLP triads were available from Denmark (1991–2001). Genotypes for 1315 SNPs in 334 autosomal cleft candidate genes were analyzed using two complementary statistical methods, TRIMM and HAPLIN, to look for genetic associations across the two national samples.

Results

Both TRIMM and HAPLIN identified strong associations between FGF12 and isolated CLO in both populations. In addition, only TRIMM identified associations with IRF6 and VCL , and only HAPLIN found an association with CX43 . When analyses were repeated on the larger sample of isolated CLP, no significant associations were found with FGF12 , IRF6, VCL or CX43 .

Conclusions

Despite some inconsistency in the pattern of associations across the two populations, the associations themselves were phenotype-specific. While both IRF6 and FGF12 have previously shown strong associations with isolated CL/P, the associations with VCL and CX43 are novel and warrant further investigation in other isolated CLO samples.

Diazepam effects on non-syndromic cleft lip with or without palate: epidemiological studies, clinical findings, genes and extracellular matrix

IMPORTANCE OF THE FIELD

This review analyses international studies investigating the combined genetic and environmental causes of cleft lip with or without cleft palate (CL/P) and describes successes and limitations in identifying underlying genetic and environmental factors. CL/P, the most common congenital facial malformation, is a major public health burden in terms of medical costs and emotional stress to patients and families. Because genetic and environmental factors determine risk of occurrence, CL/P has a complex, multifactor aetiology.

AREAS COVERED IN THIS REVIEW

English language reports from 1980 to 2010 were searched for in Medline, PubMed, Science Citation Index, textbooks and review articles on drugs and pregnancy. Key words were diazepam or benzodiazepine(s) combined with cleft lip, cleft palate, oral malformations, prenatal exposure, GABA, gene expression and extracellular matrix.

WHAT THE READER WILL GAIN

This review presents an updated assessment of the mutagenic and genotoxic effects of diazepam (DZ), one of the most commonly used benzodiazepines, on CL/P occurrence.

TAKE HOME MESSAGE

Data are divergent; more studies are needed for an in-depth picture of the effects of DZ during gestation on the child's development, particularly on orofacial clefts.

Identification of four SUMO paralogs in the medaka fish, Oryzias latipes, and their classification into two subfamilies

At least four paralogs of the small ubiquitin-related modifier (SUMO) exist in humans, but there is limited information about SUMO paralogs from other vertebrate species. We isolated the four cDNA encoding proteins, similar to human SUMOs, from the medaka fish, Oryzias latipes: OlSUMO-1, OlSUMO-2, OlSUMO-3, and OlSUMO-4. The amino acid sequences of OlSUMO-2, -3, and -4 are 89-94% identical, but they share only 45% identity with OlSUMO-1. Phylogenetic analysis, transient expression of OlSUMOs in cultured cells, and in vitro binding of OlSUMOs with two SUMO-interacting proteins demonstrated that the medaka SUMO paralogs can be grouped into two subfamilies, OlSUMO-1 and OlSUMO-2/3/4. Furthermore, this is the first report of all four OlSUMO transcripts being expressed in medaka embryos, implying that they have a role in fish development. This study will improve understanding of the relationship between structural and functional diversity of SUMO paralogs during vertebrate evolution.

Palate morphogenesis: current understanding and future directions

In the past, most scientists conducted their inquiries of nature via inductivism, the patient accumulation of "pieces of information" in the pious hope that the sum of the parts would clarify the whole. Increasingly, modern biology employs the tools of bioinformatics and systems biology in attempts to reveal the "big picture." Most successful laboratories engaged in the pursuit of the secrets of embryonic development, particularly those whose research focus is craniofacial development, pursue a middle road where research efforts embrace, rather than abandon, what some have called the "pedestrian" qualities of inductivism, while increasingly employing modern data mining technologies. The secondary palate has provided an excellent paradigm that has enabled examination of a wide variety of developmental processes. Examination of cellular signal transduction, as it directs embryogenesis, has proven exceptionally revealing with regard to clarification of the "facts" of palatal ontogeny-at least the facts as we currently understand them. Herein, we review the most basic fundamentals of orofacial embryology and discuss how functioning of TGFbeta, BMP, Shh, and Wnt signal transduction pathways contributes to palatal morphogenesis. Our current understanding of palate medial edge epithelial differentiation is also examined. We conclude with a discussion of how the rapidly expanding field of epigenetics, particularly regulation of gene expression by miRNAs and DNA methylation, is critical to control of cell and tissue differentiation, and how examination of these epigenetic processes has already begun to provide a better understanding of, and greater appreciation for, the complexities of palatal morphogenesis.

Autosomal-dominant ankyloglossia and tooth number anomalies

Ankyloglossia is a congenital oral anomaly characterized by the presence of a hypertrophic lingual frenulum. It frequently accompanies X-linked cleft palate and is sometimes seen alone due to mutations in the gene encoding the transcription factor TBX22, while knockout of Lgr5 in the mouse results in ankyloglossia. The aim of the present study was to characterize the phenotype and to verify sequence variations in the LGR5 gene in a Brazilian family with ankyloglossia associated with tooth number anomalies. Twelve individuals of three generations were submitted to physical, oral, and radiographic examinations and molecular analysis. Eight had ankyloglossia with various degrees of severity. Six also had hypodontia in the lower incisor region; one had a supernumerary tooth in this region, and another had a supernumerary tooth in the lower premolar region. The characterization of this family determined an autosomal-dominant inheritance and excluded the LGR5 gene mutations as being involved in the pathogenesis of this condition.

Lrp6-mediated canonical Wnt signaling is required for lip formation and fusion

Neither the mechanisms that govern lip morphogenesis nor the cause of cleft lip are well understood. We report that genetic inactivation of Lrp6, a co-receptor of the Wnt/beta-catenin signaling pathway, leads to cleft lip with cleft palate. The activity of a Wnt signaling reporter is blocked in the orofacial primordia by Lrp6 deletion in mice. The morphological dynamic that is required for normal lip formation and fusion is disrupted in these mutants. The expression of the homeobox genes Msx1 and Msx2 is dramatically reduced in the mutants, which prevents the outgrowth of orofacial primordia, especially in the fusion site. We further demonstrate that Msx1 and Msx2 (but not their potential regulator Bmp4) are the downstream targets of the Wnt/beta-catenin signaling pathway during lip formation and fusion. By contrast, a ;fusion-resistant' gene, Raldh3 (also known as Aldh1a3), that encodes a retinoic acid-synthesizing enzyme is ectopically expressed in the upper lip primordia of Lrp6-deficient embryos, indicating a region-specific role of the Wnt/beta-catenin signaling pathway in repressing retinoic acid signaling. Thus, the Lrp6-mediated Wnt signaling pathway is required for lip development by orchestrating two distinctively different morphogenetic movements.

Cleft lip and palate genetics and application in early embryological development

The development of the head involves the interaction of several cell populations and coordination of cell signalling pathways, which when disrupted can cause defects such as facial clefts. This review concentrates on genetic contributions to facial clefts with and without cleft palate (CP). An overview of early palatal development with emphasis on muscle and bone development is blended with the effects of environmental insults and known genetic mutations that impact human palatal development. An extensive table of known genes in syndromic and non-syndromic CP, with or without cleft lip (CL), is provided. We have also included some genes that have been identified in environmental risk factors for CP/L. We include primary and review references on this topic.

Tbx22null mice have a submucous cleft palate due to reduced palatal bone formation and also display ankyloglossia and choanal atresia phenotypes

Craniofacial defects involving the lip and/or palate are among the most common human birth defects. X-linked cleft palate and ankyloglossia results from loss-of-function mutations in the gene encoding the T-box transcription factor TBX22. Further studies show that TBX22 mutations are also found in around 5% of non-syndromic cleft palate patients. Although palate defects are obvious at birth, the underlying developmental pathogenesis remains unclear. Here, we report a Tbx22(null) mouse, which has a submucous cleft palate (SMCP) and ankyloglossia, similar to the human phenotype, with a small minority showing overt clefts. We also find persistent oro-nasal membranes or, in some mice a partial rupture, resulting in choanal atresia. Each of these defects can cause severe breathing and/or feeding difficulties in the newborn pups, which results in approximately 50% post-natal lethality. Analysis of the craniofacial skeleton demonstrates a marked reduction in bone formation in the posterior hard palate, resulting in the classic notch associated with SMCP. Our results suggest that Tbx22 plays an important role in the osteogenic patterning of the posterior hard palate. Ossification is severely reduced after condensation of the palatal mesenchyme, resulting from a delay in the maturation of osteoblasts. Rather than having a major role in palatal shelf closure, we show that Tbx22 is an important determinant for intramembranous bone formation in the posterior hard palate, which underpins normal palate development and function. These findings could have important implications for the molecular diagnosis in patients with isolated SMCP and/or unexplained choanal atresia.

SUMO proteases: redox regulation and biological consequences

Small-ubiquitin modifier (SUMO) has emerged as a novel modification system that governs the activities of a wide spectrum of protein substrates. SUMO-specific proteases (SENP) are of particular interest, as they are responsible for both the maturation of SUMO precursors and for their deconjugation. The interruption of SENPs has been implicated in embryonic defects and carcinoma cells, indicating that a proper balance of SUMO conjugation and deconjugation is crucial. Recent advances in molecular and cellular biology have highlighted the distinct subcellular localization, and endopeptidase and isopeptidase activities of SENPs, suggesting that they are nonredundant. A better understanding of the molecular basis of SUMO recognition and hydrolytic cleavage has been obtained from the crystal structures of SENP-substrate complexes. While a number of proteomic studies have shown an upregulation of sumoylation, attention is now increasingly being directed towards the regulatory mechanism of sumoylation, in particular the oxidative effect. Findings on the oxidation-induced intermolecular disulfide of E1-E2 ligases and SENP1/2 have improved our understanding of the mechanism by which modification is switched up or down. More intriguingly, a growing body of evidence suggests that sumoylation cross-talks with other modifications, and that the upstream and downstream signaling pathway is co-regulated by more than one modifier.

The PDGF-C regulatory region SNP rs28999109 decreases promoter transcriptional activity and is associated with CL/P

Human linkage and association studies suggest a gene(s) for nonsyndromic cleft lip with or without cleft palate (CL/P) on chromosome 4q31-q32 at or near the platelet-derived growth factor-C (PDGF-C) locus. The mouse Pdgfc(-/-) knockout shows that PDGF-C is essential for palatogenesis. To evaluate the role of PDGF-C in human clefting, we performed sequence analysis and SNP genotyping using 1048 multiplex CL/P families and 1000 case-control samples from multiple geographic origins. No coding region mutations were identified, but a novel -986 C>T SNP (rs28999109) was significantly associated with CL/P (P=0.01) in cases from Chinese families yielding evidence of linkage to 4q31-q32. Significant or near-significant association was also seen for this and several other PDGF-C SNPs in families from the United States, Spain, India, Turkey, China, and Colombia, whereas no association was seen in families from the Philippines, and Guatemala, and case-controls from Brazil. The -986T allele abolished six overlapping potential transcription regulatory motifs. Transfection assays of PDGF-C promoter reporter constructs show that the -986T allele is associated with a significant decrease (up to 80%) of PDGF-C gene promoter activity. This functional polymorphism acting on a susceptible genetic background may represent a component of human CL/P etiology.

Genetic determinants of facial clefting: analysis of 357 candidate genes using two national cleft studies from Scandinavia

BACKGROUND

Facial clefts are common birth defects with a strong genetic component. To identify fetal genetic risk factors for clefting, 1536 SNPs in 357 candidate genes were genotyped in two population-based samples from Scandinavia (Norway: 562 case-parent and 592 control-parent triads; Denmark: 235 case-parent triads).

METHODOLOGY/PRINCIPAL FINDINGS

We used two complementary statistical methods, TRIMM and HAPLIN, to look for associations across these two national samples. TRIMM tests for association in each gene by using multi-SNP genotypes from case-parent triads directly without the need to infer haplotypes. HAPLIN on the other hand estimates the full haplotype distribution over a set of SNPs and estimates relative risks associated with each haplotype. For isolated cleft lip with or without cleft palate (I-CL/P), TRIMM and HAPLIN both identified significant associations with IRF6 and ADH1C in both populations, but only HAPLIN found an association with FGF12. For isolated cleft palate (I-CP), TRIMM found associations with ALX3, MKX, and PDGFC in both populations, but only the association with PDGFC was identified by HAPLIN. In addition, HAPLIN identified an association with ETV5 that was not detected by TRIMM.

CONCLUSION/SIGNIFICANCE

Strong associations with seven genes were replicated in the Scandinavian samples and our approach effectively replicated the strongest previously known association in clefting--with IRF6. Based on two national cleft cohorts of similar ancestry, two robust statistical methods and a large panel of SNPs in the most promising cleft candidate genes to date, this study identified a previously unknown association with clefting for ADH1C and provides additional candidates and analytic approaches to advance the field.

Identification of microdeletions in candidate genes for cleft lip and/or palate

BACKGROUND

Genome-wide association studies are now used routinely to identify genes implicated in complex traits. The panels used for such analyses can detect single nucleotide polymorphisms and copy number variants, both of which may help to identify small deleted regions of the genome that may contribute to a particular disease.

METHODS

We performed a candidate gene analysis involving 1,221 SNPs in 333 candidate genes for orofacial clefting, using 2,823 samples from 725 two- and three-generation families with a proband having cleft lip with or without cleft palate. We used SNP genotyping, DNA sequencing, high-resolution DNA microarray analysis, and long-range PCR to confirm and characterize the deletion events.

RESULTS

This dataset had a high duplicate reproducibility rate (99.98%), high Mendelian consistency rate (99.93%), and low missing data rate (0.55%), which provided a powerful opportunity for deletion detection. Apparent Mendelian inconsistencies between parents and children suggested deletion events in 15 individuals in 11 genomic regions. We confirmed deletions involving CYP1B1, FGF10, SP8, SUMO1, TBX1, TFAP2A, and UGT7A1, including both de novo and familial cases. Deletions of SUMO1, TBX1, and TFAP2A are likely to be etiologic.

CONCLUSIONS

These deletions suggest the potential roles of genes or regulatory elements contained within deleted regions in the etiology of clefting. Our analysis took advantage of genotypes from a candidate-gene-based SNP survey and proved to be an efficient analytical approach to interrogate genes potentially involved in clefting. This can serve as a model to find genes playing a role in complex traits in general.

Patterns of some extracellular matrix gene expression are similar in cells from cleft lip-palate patients and in human palatal fibroblasts exposed to diazepam in culture

Prenatal exposure to diazepam, a prototype sedative drug that belongs to Benzodiazepines, can lead to orofacial clefting in human newborns. By using real-time PCR, in the present study we investigated whether diazepam elicits gene expression alterations in extracellular matrix (ECM) components, growth factors and gamma-aminobutyric acid receptor (GABRB3), implicated in the coordinate regulation of palate development. Palate fibroblasts were treated with diazepam (Dz-N fibroblasts) and compared to cleft lip-palate (CLP) fibroblasts obtained from patients with no known exposure to diazepam or other teratogens. Untreated fibroblasts from non-CLP patients were used as control. The results showed significant convergences in gene expression pattern of collagens, fibromodulin, vitronectin, tenascin C, integrins and metalloprotease MMP13 between Dz-N and CLP fibroblasts. Among the growth factors, constitutive Fibroblast Growth Factor 2 (FGF2) was greatly enhanced in Dz-N and CLP fibroblasts and associated with a higher reduction of FGF receptor. Transforming Growth Factor beta 3 (TGFbeta(3)) resulted up-regulated in CLP fibroblasts and decreased in Dz-N fibroblasts. We found phenotypic differences exhibited by Dz-N and CLP fibroblasts in GABRB3 gene regulation, so further studies are necessary to determine whether GABAergic system could be involved in the development of diazepam mediated CLP phenotype. Taken together the results elucidate the molecular mechanisms underlying possible toxicology effects induced by diazepam. Counselling of women on the safety of diazepam exposure is clinically important, also for the forensic consequences.