Distal-less Research Articles

Structural Variants in COL1A1 and COL1A2 in Osteogenesis Imperfecta.

Osteogenesis Imperfecta (OI) is a heterogeneous skeletal dysplasia characterized by bone fragility, skeletal deformities, and short stature. Most commonly, it is caused by autosomal dominant variants in the type I collagen genes, COL1A1 or COL1A2. Type I collagen is the main protein of the extracellular matrix in the skeleton and changes in its structure or quantity may lead to OI. 85%-90% of OI cases occur due to sequence variants in type I collagen genes, while OI caused by structural abnormalities in type I collagen genes is less common. In most cases, haploinsufficiency of type I collagen is associated with a milder OI phenotype. Large genomic deletions often involve several genes within the same chromosomal region, leading to microdeletion syndromes with OI features. Here, we report eight Swedish patients from five unrelated families with OI due to structural variants in the COL1A1 and COL1A2 genes. One patient with OI type III had a complex rearrangement with a deletion and duplication event in COL1A2, leading to reduced COL1A2 expression. Three other patients from two different families with OI type I had whole gene deletions involving COL1A1. In one family, three affected individuals with OI type I had a small intragenic deletion of exons 11-12 in COL1A2. One patient had a 2.1 Mb de novo deletion encompassing COL1A1 and DLX3 genes and features of OI and tricho-dento-osseous syndrome. Overall, this study highlights the importance of investigating gene dosage abnormalities in patients with OI and further delineates clinical and genetic variability of OI caused by structural variants in type I collagen genes.

DLX genes and proteins in mammalian forebrain development.

The vertebrate Dlx gene family encode homeobox transcription factors that are related to the Drosophila Distal-less (Dll) gene and are crucial for development. Over the last ∼35 years detailed information has accrued about the redundant and unique expression and function of the six mammalian Dlx family genes. DLX proteins interact with general transcriptional regulators, and co-bind with other transcription factors to enhancer elements with highly specific activity in the developing forebrain. Integration of the genetic and biochemical data has yielded a foundation for a gene regulatory network governing the differentiation of forebrain GABAergic neurons. In this Primer, we describe the discovery of vertebrate Dlx genes and their crucial roles in embryonic development. We largely focus on the role of Dlx family genes in mammalian forebrain development revealed through studies in mice. Finally, we highlight questions that remain unanswered regarding vertebrate Dlx genes despite over 30 years of research.

Preferential transduction of parvalbumin-expressing cortical neurons by AAV-mDLX5/6 vectors.

A major goal of modern neuroscience is to understand the functions of the varied neuronal types that comprise the mammalian brain. Toward this end, some types of neurons can be targeted and manipulated with enhancer-bearing AAV vectors. These vectors hold great promise to advance basic and translational neuroscience, but to realize this potential, their selectivity must be characterized. In this study, we investigated the selectivity of AAV vectors carrying an enhancer of the murine Dlx5 and Dlx6 genes. Vectors were injected into the visual cortex of two macaque monkeys, the frontal cortex of two others, and the somatosensory/motor cortex of three rats. Post-mortem immunostaining revealed that parvalbumin-expressing neurons were transduced efficiently in all cases but calretinin-expressing neurons were not. We speculate that this specificity is a consequence of differential activity of this DLX5/6 enhancer in adult neurons of different developmental lineages.

A novel DLX3 mutation causes tricho-dento-osseous syndrome with abnormal enamel structure and formation

ObjectiveThis study aimed to identify a DLX3 gene mutation in a family with atypical clinical manifestations of tricho-dento-osseous syndrome (TDO) and its impact on tooth enamel thickness, microhardness, structure and formation. DesignWhole-exome sequencing detected DLX3 mutations in the family. Micro-CT, Vickers hardness tester, energy dispersive spectrometer and scanning electron microscopy were performed on the deciduous teeth of the proband and controls. In vitro experiments preliminarily verified the effect of this mutation on ameloblast differentiation and suggested possible molecular mechanisms. ResultsWe found a new DLX3 frame-shift mutation (NM_005220.3: c.604_605del: p. S202 *) in this family. Compared with control teeth, the mutant enamel showed a significant decrease in thickness, hardness and calcium content and an increase in magnesium content. The enamel structure appeared disordered. In an immortalized ameloblast-lineage cell (ALC) line, this mutation affected ameloblast differentiation and downregulated the expression levels of enamel matrix protein (EMP) genes (Amelx, Tuft1, Klk4, Ambn, Odam). A luciferase reporter assay demonstrated that this mutation significantly reduced the transactivation activity of DLX3 on Amelx/Odam/Klk4. ConclusionWe found a new DLX3 mutation in a Chinese family with enamel dysplasia and that this mutation may affect ameloblast differentiation by inhibiting the transcriptional activity of Amelx/Odam/Klk4, thereby interfering with enamel formation. Our findings further expand the variation spectrum and enrich the evidence of molecular genetics of DLX3 mutations.

DLX gene expression in the developing chick pharyngeal arches and relationship to endothelin signaling and avian jaw patterning.

A hinged jaw that articulates with the skull base is a striking feature of the vertebrate head and has been greatly modified between, and within, vertebrate classes. Genes belonging to the DLX homeobox family are conserved mediators of local signaling pathways that distinguish the dorsal and ventral aspects of the first pharyngeal arch. Specifically, a subset of DLX genes are expressed in the cranial neural crest-derived mandibular ectomesenchyme in response to ventral endothelin signaling, an important step that confers the first arch with maxillary and mandibular identities. Downstream targets of DLX genes then execute the morphogenetic processes that lead to functional jaws. Identifying lineage-specific variations in DLX gene expression and the regulatory networks downstream of DLX action is necessary to understand how different kinds of jaws evolved. Here, we describe and compare the expression of all six DLX genes in the chick pharyngeal arches, focusing on the period of active patterning in the first arch. Disruption of endothelin signaling results in the down-regulation of ventral-specific DLX genes and confirms their functional role in avian jaw patterning. This expression resource will be important for comparative embryology and for identifying synexpression groups of DLX-regulated genes in the chick.

Loss of dlx5a/dlx6a Locus Alters Non-Canonical Wnt Signaling and Meckel's Cartilage Morphology.

The dlx genes encode transcription factors that establish a proximal-distal polarity within neural crest cells to bestow a regional identity during craniofacial development. The expression regions of dlx paralogs are overlapping yet distinct within the zebrafish pharyngeal arches and may also be involved in progressive morphologic changes and organization of chondrocytes of the face. However, how each dlx paralog of dlx1a, dlx2a, dlx5a and dlx6a affects craniofacial development is still largely unknown. We report here that the average lengths of the Meckel's, palatoquadrate and ceratohyal cartilages in different dlx mutants were altered. Mutants for dlx5a-/- and dlx5i6-/-, where the entire dlx5a/dlx6a locus was deleted, have the shortest lengths for all three structures at 5 days post fertilization (dpf). This phenotype was also observed in 14 dpf larvae. Loss of dlx5i6 also resulted in increased proliferation of neural crest cells and expression of chondrogenic markers. Additionally, altered expression and function of non-canonical Wnt signaling were observed in these mutants suggesting a novel interaction between dlx5i6 locus and non-canonical Wnt pathway regulating ventral cartilage morphogenesis.

A heterozygous missense variant in DLX3 leads to uterine leiomyomas and pregnancy losses in a consanguineous Iranian family

Uterine leiomyomas (ULs) are benign solid tumors arising from the uterine myometrium. They are the most common pelvic tumors among females of reproductive age. Despite the universal prevalence of ULs and its huge impact on women’s lives, the exact etiology and pathophysiologic mechanisms have not been fully understood. Numerous studies indicate that genetic factors play a crucial role in ULs development. This study aims to identify the probable genetic causes of ULs in a consanguineous Iranian family. Whole-exome sequencing (WES) on five family members with ULs revealed a likely pathogenic missense variant encoding for Y88C in the transactivation (TA) domain of DLX3 gene (c.263A > G; p.Y88C). Sanger sequencing of a total of 9 affected and non-affected family members indicated a segregation with disease with autosomal dominant inheritance. Moreover, targeted Sanger sequencing on 32 additional non-related patients with ULs showed none was heterozygous for this variant. MutPred2 predicted the pathogenicity of candidate variant by both phosphorylation and sulfation loss as actionable hypotheses. Project HOPE revealed that the identified variant residue is smaller and more hydrophobic comparing to the wild-type residue. I-TASSER and UCSF Chimera were also used for modeling and visualizing the predicted variant, respectively. This WES analysis is the first to report a variant in DLX3 variation associated with ULs pathogenicity in Iranian population highlighting the effectiveness of WES as a strong diagnostic method. However, further functional studies on this variant are needed to confirm the potential pathogenicity of this mutation.

DLX5 regulates the osteogenic differentiation of spinal ligaments cells derived from ossification of the posterior longitudinal ligament patients via NOTCH signaling.

Ossification of the posterior longitudinal ligaments (OPLL) is common disorder characterized by heterotopic ossification of the spinal ligaments. Mechanical stimulation (MS) plays an important role in OPLL. DLX5 is an essential transcription factor required for osteoblast differentiation. However, the role of DLX5 during in OPLL is unclear. This study aims to investigate whether DLX5 is associated with OPLL progression under MS. Stretch stimulation was applied to spinal ligaments cells derived from OPLL (OPLL cells) and non-OPLL (non-OPLL cells) patients. Expression of DLX5 and osteogenesis-related genes were determined by quantitative real-time polymerase chain reaction and Western blot. The osteogenic differentiation ability of the cells was measured using alkaline phosphatase (ALP) staining and alizarin red staining. The protein expression of DLX5 in the tissues and the nuclear translocation of NOTCH intracellular domain (NICD) was examined by immunofluorescence. Compared with non-OPLL cells, OPLL cells expressed higher levels of DLX5 in vitro and vivo (p < 0.01). Upregulated expression of DLX5 and osteogenesis-related genes (OSX, RUNX2, and OCN) were observed in OPLL cells induced with stretch stimulation and osteogenic medium, whereas there was no change in the non-OPLL cells (p < 0.01). Cytoplasmic NICD protein translocated from the cytoplasm to the nucleus inducing DLX5 under stretch stimulation, which was reduced by the NOTCH signaling inhibitors (DAPT) (p < 0.01). These data suggest that DLX5 play a critical role in MS-induced progression of OPLL through NOTCH signaling, which provides a new insight into the pathogenesis of OPLL.

LncRNA HOTAIR impairs the prognosis of papillary thyroid cancer via regulating cellular malignancy and epigenetically suppressing DLX1.

Papillary thyroid cancer (PTC) is the most common endocrine malignancy with a fast-growing incidence in recent decades. HOTAIR as a long non-coding RNA has been shown to be highly expressed in papillary thyroid cancer tissues with only a limited understanding of its functional roles and downstream regulatory mechanisms in papillary thyroid cancer cells. We applied three thyroid cancer cell lines (MDA-T32, MDA-T41 and K1) to investigate the phenotypic influence after gain or loss of HOTAIR. The Cancer Genome Atlas (TCGA) database were utilised to select candidate genes possibly regulated by HOTAIR with validation in the cellular system and immunohistochemical (IHC) staining of PTC tissues. We observed HOTAIR was highly expressed in MDA-T32 cells but presents significantly decreased levels in MDA-T41 and K1 cells. HOTAIR knockdown in MDA-T32 cells significantly suppressed proliferation, colony formation, migration with cell cycle retardation at G1 phase. On the contrary, HOTAIR overexpression in MDA-T41 cells dramatically enhanced proliferation, colony formation, migration with cell cycle driven toward S and G2/M phases. Similar phenotypic effects were also observed as overexpressing HOTAIR in K1 cells. To explore novel HOTAIR downstream mechanisms, we analyzed TCGA transcriptome in PTC tissues and found DLX1 negatively correlated to HOTAIR, and its lower expression associated with reduced progression free survival. We further validated DLX1 gene was epigenetically suppressed by HOTAIR via performing chromatin immunoprecipitation. Moreover, IHC staining shows a significantly stepwise decrease of DLX1 protein from normal thyroid tissues to stage III PTC tissues. Our study pointed out that HOTAIR is a key regulator of cellular malignancy and its epigenetic suppression on DLX1 serves as a novel biomarker to evaluate the PTC disease progression.

DLX Genes in the Development and Maintenance of the Vertebrate Skeleton: Implications for Human Pathologies.

Skeletal shape and mechanical properties define, to a large extent, vertebrate morphology and physical capacities. During development, skeletal morphogenesis results from dynamic communications between chondrocytes, osteoblasts, osteoclasts, and other cellular components of the skeleton. Later in life, skeletal integrity depends on the regulatory cascades that assure the equilibrium between bone formation and resorption. Finally, during aging, skeletal catabolism prevails over anabolism resulting in progressive skeletal degradation. These cellular processes depend on the transcriptional cascades that control cell division and differentiation in each cell type. Most Distal-less (Dlx) homeobox transcription factors are directly involved in determining the proliferation and differentiation of chondrocytes and osteoblasts and, indirectly, of osteoclasts. While the involvement of Dlx genes in the regulation of skeletal formation has been well-analyzed thanks to several mutant mouse models, the role of these genes in the maintenance of bone integrity has been only partially studied. The importance of Dlx genes for adult bone tissues is evidenced by their central role in the regulatory pathways involving Osx/Sp7 and Runx2, the two major master genes of osteogenesis. Dlx genes appear to be involved in several bone pathologies including, for example, osteoporosis. Indeed, at least five large-scale GWAS studies which aimed to detect loci associated with human bone mineral density (BMD) have identified a known DLX5/6 regulatory region within chromosome 7q21.3 in proximity of SEM1/FLJ42280/DSS1 coding sequences, suggesting that DLX5/6 expression is critical in determining healthy BMD. This review aims to summarize the major findings concerning the involvement of Dlx genes in skeletal development and homeostasis and their involvement in skeletal aging and pathology.

Structure, function and genoarchitectonics of the Central nucleus of the Brain’s Amygdala

The review presents the latest literature describing the Central nucleus of the Amygdala complex of the brain (CE), which is an important link in the Central autonomic nervous network. It appears in the early stages of the evolution of the telencephalon. This determines its solid phylogenetic age and explains the heteromorphy, which is manifested by the presence of a number of subnucleus: medial, intermediate, lateral and latero-capsular. The article provides information about the features of cytoarchitectonics, neural organization of subnucleus and neuropeptides. Among the latter, special attention is paid to vasopressin and oxytocin in connection with the identified new way of innervation of the amygdala complex, which has at least two origins: 1. arising from a small population of neurons localized in the intra-amygdalar portion of the bed nucleus of the stria terminalis, and 2.originating from hypothalamic neurosecretory nuclei. Afferent and efferent connections of CE are characterized. A large number of studies define the medial subnucleus as the center of integration of incoming information to the CE and the main channel for its exit from CE. At the same time, the main point where efferent connections of CE follow is the centers of the brain stem that control cardiovascular, respiratory, metabolic and motor functions. Information is provided about the main functions, including the regulation of various forms of social behavior, eating behavior, and involvement in functional reinforcement systems. The results of genetic studies indicate that CE is a derivative of the striatal division of the lateral ganglionic eminence, in the formation of which the expression of the Dlx5 and Lmo4 genes.

The insufficiency of Dlx5 for ventral patterning in post-migratory neural crest cells reveals a loss of plasticity in early jaw-forming tissue

The articulated jaws of vertebrates arise from the first pharyngeal arch, the most rostral of several transient ventral structures in pharyngeal stage embryos. Migratory cranial neural crest cells from the caudal midbrain and rostral hindbrain populate the first arch as ectomesenchyme and supply the progenitors of skeletal and soft tissues that form the upper (maxillary) and lower (mandibular) jaws. Dlx genes encode key transcriptional regulators that profoundly influence jaw development through their actions in first pharyngeal arch patterning. The broadly conserved nested expression of Dlx paralogues in vertebrate embryos points to a retained ancestral role in patterning first arch tissue. Loss-of-function experiments consistently highlight the necessity of Dlx gene function for jaw morphogenesis. Specifically, the combined effects of Dlx5 and Dlx6 are required to specify ventral/mandibular fate and forced expression of Dlx5 in migrating neural crest cells results in the ectopic upregulation of ventral markers in the maxillary arch. Here, we ask whether Dlx5 is also sufficient to respecify post-migratory ectomesenchyme in the maxillary branch as mandibular. Unexpectedly, we show that Dlx5 is not sufficient to activate mandibular marker genes in the maxillary branch of PA1, highlighting a loss of plasticity in post-migratory first arch ectomesenchyme.

Novel DLX3 variant identified in a family with tricho-dento-osseous syndrome

ObjectivesTo identify DLX3 variants in a Chinese family with typical clinical manifestations of tricho-dento-osseous syndrome (TDO). DesignSanger sequencing was performed to detect DLX3 variants in the TDO family. Three-dimensional laser scanning microscopy, bioinformatic and conformational analyses were employed to explore the phenotypic characterization and the functional impact. ResultsWe identified a novel heterozygous variant in the DLX3 gene (c.534G>C; p.Gln178His). Familial co-segregation verified an autosomal dominant inheritance pattern. Bioinformatic prediction demonstrated the deleterious effects of the variant, and DLX3 structure changes suggested the corresponding functional impairments. ConclusionsWe identified a variant in the DLX3 gene in an integrated family of Han nationality for the first time. This study expands the variant spectrum of DLX3 and phenotype spectrum of TDO syndrome.

Dlx5/6 Expression Levels in Mouse GABAergic Neurons Regulate Adult Parvalbumin Neuronal Density and Anxiety/Compulsive Behaviours.

Neuronal circuits integrating Parvalbumin-positive GABAergic inhibitory interneurons (PV) are essential for normal brain function and are often altered in psychiatric conditions. During development, Dlx5 and Dlx6 (Dlx5/6) genes are involved in the differentiation of PV-interneurons. In the adult, Dlx5/6 continue to be expressed at low levels in most telencephalic GABAergic neurons, but their importance in determining the number and distribution of adult PV-interneurons is unknown. Previously, we have shown that targeted deletion of Dlx5/6 in mouse GABAergic neurons (Dlx5/6VgatCre mice) results in altered behavioural and metabolic profiles. Here we evaluate the consequences of targeted Dlx5/6 gene dosage alterations in adult GABAergic neurons. We compare the effects on normal brain of homozygous and heterozygous (Dlx5/6VgatCre and Dlx5/6VgatCre/+ mice) Dlx5/6 deletions to those of Dlx5 targeted overexpression (GABAergicDlx5/+ mice). We find a linear correlation between Dlx5/6 allelic dosage and the density of PV-positive neurons in the adult prelimbic cortex and in the hippocampus. In parallel, we observe that Dlx5/6 expression levels in GABAergic neurons are also linearly associated with the intensity of anxiety and compulsivity-like behaviours. Our findings reinforce the notion that regulation of Dlx5/6 expression is involved in individual cognitive variability and, possibly, in the genesis of certain neuropsychiatric conditions.

Improved genome assembly of Chinese sucker (Myxocyprinus asiaticus) provides insights into the identification and characterization of pharyngeal teeth related maker genes in Cyprinoidei

The Chinese sucker, Myxocyprinus asiaticus (M. asiaticus, Catostomidae, Cypriniformes), is the only living species of Catostomidae in Asia. There are more than 75 species of this family in North America. The fossil record of this group dates back to the early Eocene. As the Chinese sucker is located at the base of the Cyprinoidei phylogeny, this species is also important in clarifying the evolutionary relationships within Cyprinoidei. Here, we assembled a high-quality genome of the Chinese sucker, contig N50 (40.26 ​Mb), which is nearly ten times longer than the previous version (4.19 ​Mb). Phylogenetic analysis identified that Chinese sucker together with Cyprinidae groups are paraphyletic with respect to Cobitoidea. The specific whole genome duplication event of the Chinese sucker was estimated to have occurred ∼25.9 million years ago. Analysis of population historical changes indicated a trend of reduction for the Chinese sucker and T. tibetana. Since Dlx genes play a key role in Cypriniformes pharyngeal teeth development, we conducted a genome-wide identification of Dlx genes, and found that these genes were doubled in whole genome duplication events, followed by the loss of specific copies. Transcriptome results showed that the expression levels of these paralogous genes were similar. This genomic resource provides useful information for the protection of Chinese sucker and functional study of Dlx genes.

Tissue Interaction in Pharyngeal Arches

The occurrence of paired pharyngeal arches (PAs) during the embryonic development of vertebrates is an essential step for the formation of head and heart structures. In fish these arches are often called branchial arches. Each PA is very simple built. On the outside is a layer of ectodermal epithelium, on the inside a layer of endodermal epithelium, and in between is a core of mesenchyme formed by mesodermal and neural crest cells. Ectoderm will give rise to outer structures and contributes to few structures connected to the inside of the head (e.g., part of tympanic membrane in tetrapods), endodermal layer will form the lining of the foregut and contributes to formations of glands, the mesodermal cells will give rise to muscles, craniofacial skeleton, and vascularization, and the neural crest cells to craniofacial skeleton and connective tissue, among others. Each arch is associated with an arch‐specific cranial nerve (CN; e.g., PA1 – trigeminal nerve, CN V; PA2 – facial nerve, CN VII, etc.) which innervates the muscles derived from the mesoderm of the same arch. Considering that the PAs are repetitive swellings lateroventrally in the developing embryonic head region in vertebrates, it is fascinating how diverse heads (and hearts) are in these animals.Gene regulatory networks (GRNs) and communication between all tissues play a crucial role in giving each arch its own identity and during differentiation of arch specific cartilages, bones, muscles, and arteries. Well‐known examples are the distribution of homeobox genes along the antero‐posterior and dorso‐ventral axis determining the identity of PAs 1‐6 (7+ in several fishes) and their proximo‐distal orientation. PA1 is determined by Otx2, while the more posterior PAs are determined by overlap of Hox2 (PA2; Hunger &amp; Prince 2002), Hox2 and Hox 3 (PA3), Hox2, Hox3, and Hox4 (PA4+) (Takio et al. 2007). Intrinsic to each arch is the dorso‐ventral axis which is patterned by Dlx genes with Dlx1 and Dlx2 being more dorsally expressed while Dlx5 and Dlx6 are more ventrally expressed (Qui et al. 1997). While these patterning mechanisms are important, the GRNs in the PAs and between tissues are still not well understood.Ectoderm and endoderm signal to the neural crest cells and mesodermal cells to differentiate, and the letter two tissues interact with each other to ensure differentiation in a highly coordinated manner. For example, the interaction of pharyngeal arch core expressed Pax9 and pharyngeal endoderm expressed Tbx1 controls the morphogenesis of the 4th pharyngeal arch artery (Phillips et al. 2019). Sonic hedgehog (Shh) is expressed in the pharyngeal ectoderm and endoderm and essential for the development of mandibular arch (1st PA)‐derived cartilages (jaw) (Billmyre &amp; Klingensmith 2015). In recent years several other examples of tissue interactions were provided. Here, I aim to provide an overview of the most recent described GRNs and tissue interactions relevant for the differentiation of PA‐derived musculature and its dependence or independence on the development of cranial nerves innervating them.ReferencesBillmyre KK &amp; Klingensmith J (2015). DevDyn 244, 564‐576.Phillips HM, et al. (2019). Development 146, dev177618.Qiu M, et al. (1997). DevBiol 185, 165‐184.Takio Y, et al. (2007). DevBiol 308, 606‐620.Trainor PA &amp; Krumlauf R (2001). CurOpCellBiol 13, 698‐705.

A Neural Crest-specific Overexpression Mouse Model Reveals the Transcriptional Regulatory Effects of Dlx2 During Maxillary Process Development.

Craniofacial morphogenesis is a complex process that requires precise regulation of cell proliferation, migration, and differentiation. Perturbations of this process cause a series of craniofacial deformities. Dlx2 is a critical transcription factor that regulates the development of the first branchial arch. However, the transcriptional regulatory functions of Dlx2 during craniofacial development have been poorly understood due to the lack of animal models in which the Dlx2 level can be precisely modulated. In this study, we constructed a Rosa26 site-directed Dlx2 gene knock-in mouse model Rosa26 CAG-LSL-Dlx2−3xFlag for conditionally overexpressing Dlx2. By breeding with wnt1 cre mice, we obtained wnt1 cre ; Rosa26 Dlx2/- mice, in which Dlx2 is overexpressed in neural crest lineage at approximately three times the endogenous level. The wnt1 cre ; Rosa26 Dlx2/- mice exhibited consistent phenotypes that include cleft palate across generations and individual animals. Using this model, we demonstrated that Dlx2 caused cleft palate by affecting maxillary growth and uplift in the early-stage development of maxillary prominences. By performing bulk RNA-sequencing, we demonstrated that Dlx2 overexpression induced significant changes in many genes associated with critical developmental pathways. In summary, our novel mouse model provides a reliable and consistent system for investigating Dlx2 functions during development and for elucidating the gene regulatory networks underlying craniofacial development.

Rs868058 in the Homeobox Gene HLX Contributes to Early-Onset Fetal Growth Restriction.

Simple SummaryFetuses with hypotrophy (FGR, fetal growth restriction) are too small for their gestational age and may be prone to various diseases and loss of life. This study aimed to determine the role of single nucleotide polymorphisms (SNPs), located in two homeotic and two angiogenesis-related genes, in the occurrence of FGR, by analyzing blood samples from 380 women in singleton pregnancies. We found that the AT heterozygotes in HLX rs868058 were significantly associated with an approximately two-fold increased risk of FGR, diagnosed before 32 weeks of gestation (early-onset FGR). AT heterozygotes were significantly more frequent in women with early-onset FGR than in those with late-onset FGR (diagnosed from 32 weeks of gestation) and compared with healthy subjects. In conclusion, the AT genotype in HLX rs868058 may be a significant risk factor for the development of early-onset FGR. So far, the only therapeutic strategy for the management of early-onset FGR is to monitor and terminate pregnancy when the risk of fetal immaturity is lower than the risk of intrauterine death. Therefore, the disclosure of the mechanisms of action of the heterozygous AT state in HLX rs868058 would be important to identify plausible targets for new therapeutic approaches to treat the condition.Fetal growth restriction (FGR) is a condition that characterizes fetuses as too small for their gestational age, with an estimated fetal weight (EFW) below the 10th percentile and abnormal Doppler parameters and/or with EFW below the 3rd percentile. We designed our study to demonstrate the contribution of single nucleotide polymorphisms (SNPs) from DLX3 (rs11656951, rs2278163, and rs10459948), HLX (rs2184658, and 868058), ANGPT2 (−35 G > C), and ITGAV (rs3911238, and rs3768777) genes in maternal blood in FGR. A cohort of 380 women with singleton pregnancies consisted of 190 pregnancies with FGR and 190 healthy full-term controls. A comparison of the pregnancies with an early-onset FGR and healthy subjects showed that the AT heterozygotes in HLX rs868058 were significantly associated with an approximately two-fold increase in disease risk (p ≤ 0.050). The AT heterozygotes in rs868058 were significantly more frequent in the cases with early-onset FGR than in late-onset FGR in the overdominant model (OR 2.08 95% CI 1.11–3.89, p = 0.022), and after being adjusted by anemia, in the codominant model (OR 2.45 95% CI 1.23–4.90, p = 0.034). In conclusion, the heterozygous AT genotype in HLX rs868058 can be considered a significant risk factor for the development of early-onset FGR, regardless of adverse pregnancy outcomes in women.

Expression variations in ectodysplasin-A gene (eda) may contribute to morphological divergence of scales in haplochromine cichlids

BackgroundElasmoid scales are one of the most common dermal appendages and can be found in almost all species of bony fish differing greatly in their shape. Whilst the genetic underpinnings behind elasmoid scale development have been investigated, not much is known about the mechanisms involved in moulding of scales. To investigate the links between gene expression differences and morphological divergence, we inferred shape variation of scales from two different areas of the body (anterior and posterior) stemming from ten haplochromine cichlid species from different origins (Lake Tanganyika, Lake Malawi, Lake Victoria and riverine). Additionally, we investigated transcriptional differences of a set of genes known to be involved in scale development and morphogenesis in fish.ResultsWe found that scales from the anterior and posterior part of the body strongly differ in their overall shape, and a separate look on scales from each body part revealed similar trajectories of shape differences considering the lake origin of single investigated species. Above all, nine as well as 11 out of 16 target genes showed expression differences between the lakes for the anterior and posterior dataset, respectively. Whereas in posterior scales four genes (dlx5, eda, rankl and shh) revealed significant correlations between expression and morphological differentiation, in anterior scales only one gene (eda) showed such a correlation. Furthermore, eda displayed the most significant expression difference between species of Lake Tanganyika and species of the other two younger lakes. Finally, we found genetic differences in downstream regions of eda gene (e.g., in the eda-tnfsf13b inter-genic region) that are associated with observed expression differences. This is reminiscent of a genetic difference in the eda-tnfsf13b inter-genic region which leads to gain or loss of armour plates in stickleback.ConclusionThese findings provide evidence for cross-species transcriptional differences of an important morphogenetic factor, eda, which is involved in formation of ectodermal appendages. These expression differences appeared to be associated with morphological differences observed in the scales of haplochromine cichlids indicating potential role of eda mediated signal in divergent scale morphogenesis in fish.

Retraction.

Retraction: "DLX5 gene regulates the Notch signaling pathway to promote glomerulosclerosis and interstitial fibrosis in uremic rats," by Xin-Fang Wang, Bei-Hao Zhang, Xiao-Qing Lu, and Rui-Qiang Wang, J Cell Physiol. 2019; 21825-21837: The above article, published online on 11 July 2019 in Wiley Online Library (https://onlinelibrary.wiley.com/doi/10.1002/jcp.28032) has been retracted by agreement between the authors, the journal's Editor in Chief, Prof. Dr. Gregg Fields, and Wiley Periodicals LLC. The retraction has been agreed after the authors stated that unintentional errors occurred during the research process, and the experimental results cannot be verified. Thus, the conclusions are considered to be invalid.