The evolutionarily conserved BMP-binding protein Twisted gastrulation promotes BMP signalling

Molecular mechanism of BMP signal control by Twisted gastrulation

Twisted gastrulation (TWSG1) is an evolutionarily conserved secreted glycoprotein which controls signaling by Bone Morphogenetic Proteins (BMPs). TWSG1 binds BMPs and their antagonist Chordin to control BMP signaling during embryonic development, kidney regeneration and cancer. We report crystal structures of TWSG1 alone and in complex with a BMP ligand, Growth Differentiation Factor 5. TWSG1 is composed of two distinct, disulfide-rich domains. The TWSG1 N-terminal domain occupies the BMP type 1 receptor binding site on BMPs, whereas the C-terminal domain binds to a Chordin family member. We show that TWSG1 inhibits BMP function in cellular signaling assays and mouse colon organoids. This inhibitory function is abolished in a TWSG1 mutant that cannot bind BMPs. The same mutation in the Drosophila TWSG1 ortholog Tsg fails to mediate BMP gradient formation required for dorsal-ventral axis patterning of the early embryo. Our studies reveal the evolutionarily conserved mechanism of BMP signaling inhibition by TWSG1.

Highly conserved and extremely evolvable: BMP signalling in secondary axis patterning of Cnidaria and Bilateria

Bilateria encompass the vast majority of the animal phyla. As the name states, they are bilaterally symmetric, that is with a morphologically clear main body axis connecting their anterior and posterior ends, a second axis running between their dorsal and ventral surfaces, and with a left side being roughly a mirror image of their right side. Bone morphogenetic protein (BMP) signalling has widely conserved functions in the formation and patterning of the second, dorso-ventral (DV) body axis, albeit to different extents in different bilaterian species. Whilst initial findings in the fruit fly Drosophila and the frog Xenopus highlighted similarities amongst these evolutionarily very distant species, more recent analyses featuring other models revealed considerable diversity in the mechanisms underlying dorsoventral patterning. In fact, as phylogenetic sampling becomes broader, we find that this axis patterning system is so evolvable that even its core components can be deployed differently or lost in different model organisms. In this review, we will try to highlight the diversity of ways by which BMP signalling controls bilaterality in different animals, some of which do not belong to Bilateria. Future research combining functional analyses and modelling is bound to give us some understanding as to where the limits to the extent of the evolvability of BMP-dependent axial patterning may lie.

Roles of bone morphogenetic proteins in endometrial remodeling during the human menstrual cycle and pregnancy

BACKGROUND

During the human menstrual cycle and pregnancy, the endometrium undergoes a series of dynamic remodeling processes to adapt to physiological changes. Insufficient endometrial remodeling, characterized by inadequate endometrial proliferation, decidualization and spiral artery remodeling, is associated with infertility, endometriosis, dysfunctional uterine bleeding, and pregnancy-related complications such as preeclampsia and miscarriage. Bone morphogenetic proteins (BMPs), a subset of the transforming growth factor-β (TGF-β) superfamily, are multifunctional cytokines that regulate diverse cellular activities, such as differentiation, proliferation, apoptosis, and extracellular matrix synthesis, are now understood as integral to multiple reproductive processes in women. Investigations using human biological samples have shown that BMPs are essential for regulating human endometrial remodeling processes, including endometrial proliferation and decidualization.

OBJECTIVE AND RATIONALE

This review summarizes our current knowledge on the known pathophysiological roles of BMPs and their underlying molecular mechanisms in regulating human endometrial proliferation and decidualization, with the goal of promoting the development of innovative strategies for diagnosing, treating and preventing infertility and adverse pregnancy complications associated with dysregulated human endometrial remodeling.

SEARCH METHODS

A literature search for original articles published up to June 2023 was conducted in the PubMed, MEDLINE, and Google Scholar databases, identifying studies on the roles of BMPs in endometrial remodeling during the human menstrual cycle and pregnancy. Articles identified were restricted to English language full-text papers.

OUTCOMES

BMP ligands and receptors and their transduction molecules are expressed in the endometrium and at the maternal-fetal interface. Along with emerging technologies such as tissue microarrays, 3D organoid cultures and advanced single-cell transcriptomics, and given the clinical availability of recombinant human proteins and ongoing pharmaceutical development, it is now clear that BMPs exert multiple roles in regulating human endometrial remodeling and that these biomolecules (and their receptors) can be targeted for diagnostic and therapeutic purposes. Moreover, dysregulation of these ligands, their receptors, or signaling determinants can impact endometrial remodeling, contributing to infertility or pregnancy-related complications (e.g. preeclampsia and miscarriage).

WIDER IMPLICATIONS

Although further clinical trials are needed, recent advancements in the development of recombinant BMP ligands, synthetic BMP inhibitors, receptor antagonists, BMP ligand sequestration tools, and gene therapies have underscored the BMPs as candidate diagnostic biomarkers and positioned the BMP signaling pathway as a promising therapeutic target for addressing infertility and pregnancy complications related to dysregulated human endometrial remodeling.

Opsin-Free Activation of Bmp Receptors by a Femtosecond Laser

Bone morphogenetic protein (BMP) signaling plays a vital role in differentiation, organogenesis, and various cell processes. As a member of TGF-β superfamily, the BMP initiation usually accompanies crosstalk with other signaling pathways and simultaneously activates some of them. It is quite challenging to solely initiate an individual pathway. In this study, an opsin-free optical method to specifically activate BMP receptors (BMPR) and subsequent pSmad1/5/8 cascades by a single-time scan of a tightly-focused femtosecond laser in the near infrared range is reported. Via transient two-photon excitation to intrinsic local flavins near the cell membrane, the photoactivation drives conformational changes of preformed BMPR complexes to enable their bonding and phosphorylation of the GS domain in BMPR-I by BMPR-II. The pSmad1/5/8 signaling is initiated by this method, while p38 and pSmad2 are rarely perturbed. Based on a microscopic system, primary adipose-derived stem cells in an area of 420  × 420 µm2 are photoactivated by a single-time laser scanning for 1.5 s and exhibit pSmad1/5/8 upregulation and osteoblastic differentiation after 21 days. Hence, an opsin-free, specific, and noninvasive optical method to initiate BMP signaling, easily accomplished by a two-photon microscope system is reported.

Reconstitution of morphogen shuttling circuits

Developing tissues form spatial patterns by establishing concentration gradients of diffusible signaling proteins called morphogens. The bone morphogenetic protein (BMP) morphogen pathway uses a family of extracellular modulators to reshape signaling gradients by actively "shuttling" ligands to different locations. It has remained unclear what circuits are sufficient to enable shuttling, what other patterns they can generate, and whether shuttling is evolutionarily conserved. Here, using a synthetic, bottom-up approach, we compared the spatiotemporal dynamics of different extracellular circuits. Three proteins-Chordin, Twsg, and the BMP-1 protease-successfully displaced gradients by shuttling ligands away from the site of production. A mathematical model explained the different spatial dynamics of this and other circuits. Last, combining mammalian and Drosophila components in the same system suggests that shuttling is a conserved capability. Together, these results reveal principles through which extracellular circuits control the spatiotemporal dynamics of morphogen signaling.

BMPER Improves Vascular Remodeling and the Contractile Vascular SMC Phenotype

Dedifferentiated vascular smooth muscle cells (vSMCs) play an essential role in neointima formation, and we now aim to investigate the role of the bone morphogenetic protein (BMP) modulator BMPER (BMP endothelial cell precursor-derived regulator) in neointima formation. To assess BMPER expression in arterial restenosis, we used a mouse carotid ligation model with perivascular cuff placement. Overall BMPER expression after vessel injury was increased; however, expression in the tunica media was decreased compared to untreated control. Consistently, BMPER expression was decreased in proliferative, dedifferentiated vSMC in vitro. C57BL/6_Bmper+/- mice displayed increased neointima formation 21 days after carotid ligation and enhanced expression of Col3A1, MMP2, and MMP9. Silencing of BMPER increased the proliferation and migration capacity of primary vSMCs, as well as reduced contractibility and expression of contractile markers, whereas stimulation with recombinant BMPER protein had the opposite effect. Mechanistically, we showed that BMPER binds insulin-like growth factor-binding protein 4 (IGFBP4), resulting in the modulation of IGF signaling. Furthermore, perivascular application of recombinant BMPER protein prevented neointima formation and ECM deposition in C57BL/6N mice after carotid ligation. Our data demonstrate that BMPER stimulation causes a contractile vSMC phenotype and suggest that BMPER has the potential for a future therapeutic agent in occlusive cardiovascular diseases.

Multifaceted Functions of TWSG1: From Embryogenesis to Cancer Development

Bone morphogenetic proteins (BMPs) play an important role in development. Twisted gastrulation BMP signaling modulator 1 (TWSG1) was initially identified as a regulator of the dorsoventral axis formation in Drosophila. The mechanism of BMP signaling modulation by TWSG1 is complex. TWSG1 inhibits BMP signaling by binding to BMP ligands including BMP4, whereas it enhances signaling by interacting with Chordin, a BMP antagonist. Therefore, TWSG1 can act as both a BMP agonist and antagonist. TWSG1 has various functions ranging from embryogenesis to cancer progression. TWSG1 knockout mice showed neural, craniofacial, and mammary defects. TWSG1 also regulated erythropoiesis and thymocyte development. Furthermore, the relationship between TWSG1 and cancer has been elucidated. Allelic loss of TWSG1 was detected in colorectal cancer. TWSG1 expression was upregulated in papillary thyroid carcinoma and glioblastoma but downregulated in gastric and endometrial cancers. TWSG1 suppressed BMP7-enhanced sphere formation and migration in endometrial cancer cells, indicating its tumor-suppressive role. Further studies are required to clarify the TWSG1 function and its association with BMP signaling in cancer development. Finally, TWSG1 is abundantly expressed in human and mouse ovaries and sustains follicular growth in rodent ovaries. Thus, TWSG1 has various functions ranging from fertility to cancer. Therefore, TWSG1 signaling modulation may be beneficial in treating specific diseases such as cancer.

Effect of quercetin on muscle growth and antioxidant status of the dark sleeper Odontobutis potamophila

Quercetin is a flavanol beneficial in reducing fat, promoting muscle growth, and Anti-oxidation. To study its effects in freshwater fish, the full-length cDNA of the follistatin (FST) and myostatin (MSTN) genes of the dark sleeper Odontobutis potamophila were cloned for the first time. Juvenile individual O. potamophila was exposed to quercetin at one of four concentrations (0, 2.5, 5, and 10 mg/L) for 21 days. The expression level of MSTN which inhibits muscle growth in the quercetin solution was lower than in the unexposed control group. The genes that promote muscle growth are in TGF-β superfamily like FST, TGF-β1 (transforming growth factor-beta 1), and Myogenic regulatory factors (MRFs) like Myf5 (myogenic factor 5), MyoD (myogenic differentiation), MyoG (myogenin), were higher than in the control group. Apolipoprotein and growth hormone receptor transcription levels in the quercetin-treated fish were significantly lower than in the control group. The concentrations of triglyceride, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol in the muscle tissue decreased, and the lipid-lowering function of quercetin was also demonstrated at the biochemical level. In this study, we analyzed the mRNA levels of AKT, Keap1 (kelch-like ECH-associated protein 1), Nrf2 (NF-E2-related factor 2) oxidation-related genes in the Nrf2/ARE antioxidant pathway, and Malondialdehyde (MDA), catalase (CAT) activity and glutathione (GSH) content in the hepatopancreas of O. potamophila after quercetin treatment, the mRNA expression of AKT, Nrf2 and CAT activity and GSH content are higher than in the control group. Quercetin enhances antioxidant properties and positively affects muscle growth. The results showed that quercetin has no significant effects on the growth performance of O. potamophila, but is effective in increasing muscle growth rate and lowering muscle fat content.

BMP Signaling: Lighting up the Way for Embryonic Dorsoventral Patterning

One of the most significant events during early embryonic development is the establishment of a basic embryonic body plan, which is defined by anteroposterior, dorsoventral (DV), and left-right axes. It is well-known that the morphogen gradient created by BMP signaling activity is crucial for DV axis patterning across a diverse set of vertebrates. The regulation of BMP signaling during DV patterning has been strongly conserved across evolution. This is a remarkable regulatory and evolutionary feat, as the BMP gradient has been maintained despite the tremendous variation in embryonic size and shape across species. Interestingly, the embryonic DV axis exhibits robust stability, even in face of variations in BMP signaling. Multiple lines of genetic, molecular, and embryological evidence have suggested that numerous BMP signaling components and their attendant regulators act in concert to shape the developing DV axis. In this review, we summarize the current knowledge of the function and regulation of BMP signaling in DV patterning. Throughout, we focus specifically on popular model animals, such as Xenopus and zebrafish, highlighting the similarities and differences of the regulatory networks between species. We also review recent advances regarding the molecular nature of DV patterning, including the initiation of the DV axis, the formation of the BMP gradient, and the regulatory molecular mechanisms behind BMP signaling during the establishment of the DV axis. Collectively, this review will help clarify our current understanding of the molecular nature of DV axis formation.

Expression profiling of ovarian BMP antagonists reveals the potential interaction between TWSG1 and the chordin subfamily in the ovary

The TGF-β superfamily members and their antagonists comprise an indispensable system that controls mammalian ovarian development in a sophisticated manner. In contrast to a plethora of studies on the ovary-expressed TGF-β superfamily members, knowledge regarding their antagonists, including their expression profiles and antagonism preferences, is still lacking. Using quantitative PCR in rats and transcriptomic dataset comparisons in mice and humans, we set out to characterize the relative expression levels of most antagonists in the mammalian ovary. We found that Twsg1 and Nbl1 are the most abundant BMP antagonists expressed in the rodent and human ovaries, respectively. TWSG1 has been reported to have synergistic action with the chordin subfamily, including CHRD and CHRDL1, the genes of which also showed moderate expression in the mammalian ovary. Therefore, their ovarian expression profiles and antagonisms against the ovary-expressed TGF-β superfamily members were further characterized. Bioactivity tests indicated that TWSG1 alone can directly inhibit the signaling of BMP6 or BMP7. In addition, it can further enhance the antagonizing ability of CHRD towards BMP2, BMP4, BMP7 and GDF5, or CHRDL1's antagonism towards BMP2, BMP4, GDF5 and activin A. In combination with their distinct transcript profiles in ovarian compartments, our findings suggest that TWSG1 may work coordinately with CHRD within theca/interstitial shells and also with CHRDL1 in developing granulosa cells; these interactions would modulate the intraovarian functions of the TGF-β superfamily members, such as the control of progesterone production.

Application of the RNA interference technique to Xenopus embryos: Specific reduction of the β-catenin gene products by short double-stranded RNA produced by recombinant human Dicer

RNA interference (RNAi) is a technique for suppressing the function of specific genes and is widely used in many organisms, including yeast, nematodes, flies, plants, mice, and cultured mammalian cells. As of date, this technique has not been successfully applied to Xenopus laevis embryos. In this study, we applied RNAi to Xenopus embryos using β-catenin as a model gene. Injection of long double-stranded RNA (dsRNA) corresponding to the 3'-untranslated region of β-catenin mRNA into embryos induced embryonic lethality without any specific phenotype. However, injection of short dsRNA, generated from long dsRNA by treatment with recombinant human Dicer, into embryos resulted in decreased expression of endogenous β-catenin mRNA and protein, as well as decreased Wnt signaling activity in the embryos. The decrease in β-catenin mRNA and protein levels was observed only after mid-blastula transition. Embryos injected with short dsRNA showed a characteristic phenotype of enlarged anterior structures and loss of posterior structures. These phenotypes, as well as the increased expression of the anterior gene and decreased expression of the posterior gene, suggest that RNAi against the β-catenin gene suppresses the "late Wnt signaling" involved in proper anterior-posterior patterning of Xenopus embryos. The effect of RNAi on Xenopus embryos was also found to be sensitive to temperature. These results strongly suggest that the RNAi technique can be applied to Xenopus embryos using short dsRNAs, appropriate temperature control, and proper selection of target genes.

BMP antagonists in tissue development and disease

Bone morphogenic proteins (BMPs) are important growth regulators in embryogenesis and postnatal homeostasis. Their tight regulation is crucial for successful embryonic development as well as tissue homeostasis in the adult organism. BMP inhibition by natural extracellular biologic antagonists represents the most intensively studied mechanistic concept of BMP growth factor regulation. It was shown to be critical for numerous developmental programs, including germ layer specification and spatiotemporal gradients required for the establishment of the dorsal-ventral axis and organ formation. The importance of BMP antagonists for extracellular matrix homeostasis is illustrated by the numerous human connective tissue disorders caused by their mutational inactivation. Here, we will focus on the known functional interactions targeting BMP antagonists to the ECM and discuss how these interactions influence BMP antagonist activity. Moreover, we will provide an overview about the current concepts and investigated molecular mechanisms modulating BMP inhibitor function in the context of development and disease.

Tumor Promoting Effect of BMP Signaling in Endometrial Cancer

The effects of bone morphogenetic proteins (BMPs), members of the transforming growth factor-β (TGF-β) family, in endometrial cancer (EC) have yet to be determined. In this study, we analyzed the TCGA and MSK-IMPACT datasets and investigated the effects of BMP2 and of TWSG1, a BMP antagonist, on Ishikawa EC cells. Frequent ACVR1 mutations and high mRNA expressions of BMP ligands and receptors were observed in EC patients of the TCGA and MSK-IMPACT datasets. Ishikawa cells secreted higher amounts of BMP2 compared with ovarian cancer cell lines. Exogenous BMP2 stimulation enhanced EC cell sphere formation via c-KIT induction. BMP2 also induced EMT of EC cells, and promoted migration by induction of SLUG. The BMP receptor kinase inhibitor LDN193189 augmented the growth inhibitory effects of carboplatin. Analyses of mRNAs of several BMP antagonists revealed that TWSG1 mRNA was abundantly expressed in Ishikawa cells. TWSG1 suppressed BMP7-induced, but not BMP2-induced, EC cell sphere formation and migration. Our results suggest that BMP signaling promotes EC tumorigenesis, and that TWSG1 antagonizes BMP7 in EC. BMP signaling inhibitors, in combination with chemotherapy, might be useful in the treatment of EC patients.

Structural perspective of BMP ligands and signaling

The Bone Morphogenetic Proteins (BMPs) are the largest class signaling molecules within the greater Transforming Growth Factor Beta (TGFβ) family, and are responsible for a wide array of biological functions, including dorsal-ventral patterning, skeletal development and maintenance, as well as cell homeostasis. As such, dysregulation of BMPs results in a number of diseases, including fibrodysplasia ossificans progressiva (FOP) and pulmonary arterial hypertension (PAH). Therefore, understanding BMP signaling and regulation at the molecular level is essential for targeted therapeutic intervention. This review discusses the recent advances in the structural and biochemical characterization of BMPs, from canonical ligand-receptor interactions to co-receptors and antagonists. This work aims to highlight how BMPs differ from other members of the TGFβ family, and how that information can be used to further advance the field. Lastly, this review discusses several gaps in the current understanding of BMP structures, with the aim that discussion of these gaps will lead to advancements in the field.

Functional evidence that Activin/Nodal signaling is required for establishing the dorsal-ventral axis in the annelid Capitella teleta

The TGF-β superfamily comprises two distinct branches: the Activin/Nodal and BMP pathways. During development, signaling by this superfamily regulates a variety of embryological processes, and it has a conserved role in patterning the dorsal-ventral body axis. Recent studies show that BMP signaling establishes the dorsal-ventral axis in some mollusks. However, previous pharmacological inhibition studies in the annelid Capitella teleta, a sister clade to the mollusks, suggests that the dorsal-ventral axis is patterned via Activin/Nodal signaling. Here, we determine the role of both the Activin/Nodal and BMP pathways as they function in Capitella axis patterning. Antisense morpholino oligonucleotides were targeted to Ct-Smad2/3 and Ct-Smad1/5/8, transcription factors specific to the Activin/Nodal and BMP pathways, respectively. Following microinjection of zygotes, resulting morphant larvae were scored for axial anomalies. We demonstrate that the Activin/Nodal pathway of the TGF-β superfamily, but not the BMP pathway, is the primary dorsal-ventral patterning signal in Capitella. These results demonstrate variation in the molecular control of axis patterning across spiralians, despite sharing a conserved cleavage program. We suggest that these findings represent an example of developmental system drift.

Summary: Morpholino knockdown experiments in the annelid Capitella teleta demonstrate that the dorsal-ventral axis is primarily patterned by the Activin/Nodal pathway of the TGF-β superfamily, rather than by the BMP pathway.

Bone Morphogenetic Protein-2 in Development and Bone Homeostasis

Bone morphogenetic proteins (BMPs) are multi-functional growth factors belonging to the Transforming Growth Factor-Beta (TGF-β) superfamily. These proteins are essential to many developmental processes, including cardiogenesis, neurogenesis, and osteogenesis. Specifically, within the BMP family, Bone Morphogenetic Protein-2 (BMP-2) was the first BMP to be characterized and has been well-studied. BMP-2 has important roles during embryonic development, as well as bone remodeling and homeostasis in adulthood. Some of its specific functions include digit formation and activating osteogenic genes, such as Runt-Related Transcription Factor 2 (RUNX2). Because of its diverse functions and osteogenic potential, the Food and Drug Administration (FDA) approved usage of recombinant human BMP-2 (rhBMP-2) during spinal fusion surgery, tibial shaft repair, and maxillary sinus reconstructive surgery. However, shortly after initial injections of rhBMP-2, several adverse complications were reported, and alternative therapeutics have been developed to limit these side-effects. As the clinical application of BMP-2 is largely implicated in bone, we focus primarily on its role in bone. However, we also describe briefly the role of BMP-2 in development. We then focus on the structure of BMP-2, its activation and regulation signaling pathways, BMP-2 clinical applications, and limitations of using BMP-2 as a therapeutic. Further, this review explores other potential treatments that may be useful in treating bone disorders.

Differential Proteomic Analysis Predicts Appropriate Applications for the Secretome of Adipose-Derived Mesenchymal Stem/Stromal Cells and Dermal Fibroblasts

The adult stem cell secretome is currently under investigation as an alternative to cell-based therapy in regenerative medicine, thanks to the remarkable translational opportunity and the advantages in terms of handling and safety. In this perspective, we recently demonstrated the efficient performance of the adipose-derived mesenchymal stem/stromal cell (ASC) secretome in contrasting neuroinflammation in a murine model of diabetic neuropathy, where the administration of factors released by dermal fibroblasts (DFs) did not exert any effect. Up to now, the complex mixture of the constituents of the conditioned medium from ASCs has not been fully deepened, although its appropriate characterization is required in the perspective of a clinical use. Herein, we propose the differential proteomic approach for the identification of the players accounting for the functional effects of the cell secretome with the aim to unravel its appropriate applications. Out of 967 quantified proteins, 34 and 62 factors were found preponderantly or exclusively secreted by ASCs and DFs, respectively. This approach led to the recognition of distinct functions related to the conditioned medium of ASCs and DFs, with the former being involved in the regulation of neuronal death and apoptosis and the latter in bone metabolism and ossification. The proosteogenic effect of DF secretome was validated in vitro on human primary osteoblasts, providing a proof of concept of its osteoinductive potential. Besides discovering new applications of the cell type-specific secretome, the proposed strategy could allow the recognition of the cocktail of bioactive factors which might be responsible for the effects of conditioned media, thus providing a solid rationale to the implementation of a cell-free approach in several clinical scenarios involving tissue regeneration.

TGF-β Family Signaling in Early Vertebrate Development

TGF-β family ligands function in inducing and patterning many tissues of the early vertebrate embryonic body plan. Nodal signaling is essential for the specification of mesendodermal tissues and the concurrent cellular movements of gastrulation. Bone morphogenetic protein (BMP) signaling patterns tissues along the dorsal-ventral axis and simultaneously directs the cell movements of convergence and extension. After gastrulation, a second wave of Nodal signaling breaks the symmetry between the left and right sides of the embryo. During these processes, elaborate regulatory feedback between TGF-β ligands and their antagonists direct the proper specification and patterning of embryonic tissues. In this review, we summarize the current knowledge of the function and regulation of TGF-β family signaling in these processes. Although we cover principles that are involved in the development of all vertebrate embryos, we focus specifically on three popular model organisms: the mouse Mus musculus, the African clawed frog of the genus Xenopus, and the zebrafish Danio rerio, highlighting the similarities and differences between these species.

Global differential gene expression in the pituitary gland and the ovaries of pre- and postpubertal Brahman heifers

To understand genes, pathways, and networks related to puberty, we characterized the transcriptome of two tissues: the pituitary gland and ovaries. Samples were harvested from pre- and postpubertal Brahman heifers (same age group). Brahman heifers () are older at puberty compared with , a productivity issue. With RNA sequencing, we identified differentially expressed (DEx) genes and important transcription factors (TF) and predicted coexpression networks. The number of DEx genes detected in the pituitary gland was 284 ( < 0.05), and was the most DEx gene (fold change = 4.12, = 0.01). The gene promotes bone mineralization through transforming growth factor-β (TGFβ) signaling. Further studies of the link between bone mineralization and puberty could target . In ovaries, 3,871 genes were DEx ( < 0.05). Four highly DEx genes were noteworthy for their function: (a γ-aminobutyric acid [GABA] transporter), (), and () and its receptor . These genes had higher ovarian expression in postpubertal heifers. The GABA and its receptors and transporters were expressed in the ovaries of many mammals, suggesting a role for this pathway beyond the brain. The pathway has been known to influence the timing of puberty in rats, via modulation of GnRH. The effects of at the hypothalamus, pituitary gland, and ovaries have been documented. and its receptors are known factors in the release of GnRH, similar to and GABA, although their roles in ovarian tissue are less clear. Pathways previously related to puberty such as TGFβ signaling ( = 6.71 × 10), Wnt signaling ( = 4.1 × 10), and peroxisome proliferator-activated receptor (PPAR) signaling ( = 4.84 × 10) were enriched in our data set. Seven genes were identified as key TF in both tissues: , , , , , , and a novel gene. An ovarian subnetwork created with TF and significant ovarian DEx genes revealed five zinc fingers as regulators: , , , , and . Recent work of hypothalamic gene expression also pointed to zinc fingers as TF for bovine puberty. Although some zinc fingers may be ubiquitously expressed, the identification of DEx genes in common across tissues points to key regulators of puberty. The hypothalamus and pituitary gland had eight DEx genes in common. The hypothalamus and ovaries had 89 DEx genes in common. The pituitary gland and ovaries had 48 DEx genes in common. Our study confirmed the complexity of puberty and suggested further investigation on genes that code zinc fingers.

TGF-β Family Signaling in Neural and Neuronal Differentiation, Development, and Function

Signaling by the transforming growth factor β (TGF-β) family is necessary for proper neural development and function throughout life. Sequential waves of activation, inhibition, and reactivation of TGF-β family members regulate numerous elements of the nervous system from the earliest stages of embryogenesis through adulthood. This review discusses the expression, regulation, and function of TGF-β family members in the central nervous system at various developmental stages, beginning with induction and patterning of the nervous system to their importance in the adult as modulators of inflammatory response and involvement in degenerative diseases.

The maternal control in the embryonic development of zebrafish

The maternal control directing the very first hours of life is of pivotal importance for ensuring proper development to the growing embryo. Thanks to the finely regulated inheritance of maternal factors including mRNAs and proteins produced during oogenesis and stored into the mature oocyte, the embryo is sustained throughout the so-called maternal-to-zygotic transition, a period in development characterized by a species-specific length in time, during which critical biological changes regarding cell cycle and zygotic transcriptional activation occur. In order not to provoke any kind of persistent damage, the process must be delicately balanced. Surprisingly, our knowledge as to the possible effects of beneficial bacteria regarding the modulation of the quality and/or quantity of both maternally-supplied and zygotically-transcribed mRNAs, is very limited. To date, only one group has investigated the consequences of the parentally-supplied Lactobacillus rhamnosus on the storage of mRNAs into mature oocytes, leading to an altered maternal control process in the F1 generation. Particular attention was called on the monitoring of several biomarkers involved in autophagy, apoptosis and axis patterning, while data on miRNA generation and pluripotency maintenance are herein presented for the first time, and can assist in laying the ground for further investigations in this field. In this review, the reader is supplied with the current knowledge on the above-mentioned biological process, first by drawing the general background and then by emphasizing the most important findings that have highlighted their focal role in normal animal development.

Extracellular regulation of BMP signaling: welcome to the matrix

Given its importance in development and homeostasis, bone morphogenetic protein (BMP) signaling is tightly regulated at the extra- and intracellular level. The extracellular matrix (ECM) was initially thought to act as a passive mechanical barrier that sequesters BMPs. However, a new understanding about how the ECM plays an instructive role in regulating BMP signaling is emerging. In this mini-review, we discuss various ways in which the biochemical and physical properties of the ECM regulate BMP signaling.

Scaling of pattern formations and morphogen gradients

The concentration gradient of morphogens provides positional information for an embryo and plays a pivotal role in pattern formation of tissues during the developmental processes. Morphogen-dependent pattern formations show robustness despite various perturbations. Although tissues usually grow and dynamically change their size during histogenesis, proper patterns are formed without the influence of size variations. Furthermore, even when the blastula embryo of Xenopus laevis is bisected into dorsal and ventral halves, the dorsal half of the embryo leads to proportionally patterned half-sized embryos. This robustness of pattern formation despite size variations is termed as scaling. In this review, I focused on the morphogen-dependent dorsal-ventral axis formation in Xenopus and described how morphogens form a proper gradient shape according to the embryo size.

Structural Biology and Evolution of the TGF-β Family

We review the evolution and structure of members of the transforming growth factor β (TGF-β) family, antagonistic or agonistic modulators, and receptors that regulate TGF-β signaling in extracellular environments. The growth factor (GF) domain common to all family members and many of their antagonists evolved from a common cystine knot growth factor (CKGF) domain. The CKGF superfamily comprises six distinct families in primitive metazoans, including the TGF-β and Dan families. Compared with Wnt/Frizzled and Notch/Delta families that also specify body axes, cell fate, tissues, and other families that contain CKGF domains that evolved in parallel, the TGF-β family was the most fruitful in evolution. Complexes between the prodomains and GFs of the TGF-β family suggest a new paradigm for regulating GF release by conversion from closed- to open-arm procomplex conformations. Ternary complexes of the final step in extracellular signaling show how TGF-β GF dimers bind type I and type II receptors on the cell surface, and enable understanding of much of the specificity and promiscuity in extracellular signaling. However, structures suggest that when GFs bind repulsive guidance molecule (RGM) family coreceptors, type I receptors do not bind until reaching an intracellular, membrane-enveloped compartment, blurring the line between extra- and intracellular signaling. Modulator protein structures show how structurally diverse antagonists including follistatins, noggin, and members of the chordin family bind GFs to regulate signaling; complexes with the Dan family remain elusive. Much work is needed to understand how these molecular components assemble to form signaling hubs in extracellular environments in vivo.

Structural characterization of twisted gastrulation provides insights into opposing functions on the BMP signalling pathway

Twisted gastrulation (Tsg) and chordin are secreted glycoproteins that function together as BMP (bone morphogenetic protein) antagonists to regulate BMP growth factor signalling. Chordin binds to BMPs, preventing them from interacting with their receptors and Tsg is known to strengthen this inhibitory complex. Tsg also acts as a BMP agonist by promoting cleavage of chordin by tolloid-family proteinases. Here we explore the structural mechanism through which Tsg exerts this dual activity. We have characterized the nanoscale structure of human Tsg using in-solution biomolecular analysis and show that Tsg is a globular monomer with a flattened cross shape. Tsg has a high proportion of N-linked glycans, in relation to its molecular weight, which supports a role in solubilising BMPs. Tsg binds with high affinity to the C-terminal region of chordin and was also able to inhibit BMP-7 signalling directly but did not have an effect on BMP-4 signalling. Although both Tsg and mammalian tolloid are involved in chordin cleavage, no interaction could be detected between them using surface plasmon resonance. Together these data suggest that Tsg functions as a BMP-agonist by inducing conformational change in chordin making it more susceptible to tolloid cleavage and as a BMP-antagonist either independently or via a chordin-mediated mechanism. Following single cleavage of chordin by tolloids, Tsg continues to strengthen the inhibitory complex, supporting a role for partially cleaved chordin in BMP regulation.

Agonists and Antagonists of TGF-β Family Ligands

The discovery of the transforming growth factor β (TGF-β) family ligands and the realization that their bioactivities need to be tightly controlled temporally and spatially led to intensive research that has identified a multitude of extracellular modulators of TGF-β family ligands, uncovered their functions in developmental and pathophysiological processes, defined the mechanisms of their activities, and explored potential modulator-based therapeutic applications in treating human diseases. These studies revealed a diverse repertoire of extracellular and membrane-associated molecules that are capable of modulating TGF-β family signals via control of ligand availability, processing, ligand-receptor interaction, and receptor activation. These molecules include not only soluble ligand-binding proteins that were conventionally considered as agonists and antagonists of TGF-β family of growth factors, but also extracellular matrix (ECM) proteins and proteoglycans that can serve as "sink" and control storage and release of both the TGF-β family ligands and their regulators. This extensive network of soluble and ECM modulators helps to ensure dynamic and cell-specific control of TGF-β family signals. This article reviews our knowledge of extracellular modulation of TGF-β growth factors by diverse proteins and their molecular mechanisms to regulate TGF-β family signaling.

Mammalian tolloid proteinases: role in growth factor signalling

Tolloid proteinases are essential for tissue patterning and extracellular matrix assembly. The members of the family differ in their substrate specificity and activity, despite sharing similar domain organization. The mechanisms underlying substrate specificity and activity are complex, with variation between family members, and depend on both multimerization and substrate interaction. In addition, enhancers, such as Twisted gastrulation (Tsg), promote cleavage of tolloid substrate, chordin, to regulate growth factor signalling. Although Tsg and mammalian tolloid (mTLD) are involved in chordin cleavage, no interaction has been detected between them, suggesting Tsg induces a change in chordin to increase susceptibility to cleavage. All members of the tolloid family bind the N terminus of latent TGFβ‐binding protein‐1, providing support for their role in TGFβ signalling.

Identification and functional analysis of secreted effectors from phytoparasitic nematodes

BACKGROUND

Plant parasitic nematodes develop an intimate and long-term feeding relationship with their host plants. They induce a multi-nucleate feeding site close to the vascular bundle in the roots of their host plant and remain sessile for the rest of their life. Nematode secretions, produced in the oesophageal glands and secreted through a hollow stylet into the host plant cytoplasm, are believed to play key role in pathogenesis. To combat these persistent pathogens, the identity and functional analysis of secreted effectors can serve as a key to devise durable control measures. In this review, we will recapitulate the knowledge over the identification and functional characterization of secreted nematode effector repertoire from phytoparasitic nematodes.

RESEARCH

Despite considerable efforts, the identity of genes encoding nematode secreted proteins has long been severely hampered because of their microscopic size, long generation time and obligate biotrophic nature. The methodologies such as bioinformatics, protein structure modeling, in situ hybridization microscopy, and protein-protein interaction have been used to identify and to attribute functions to the effectors. In addition, RNA interference (RNAi) has been instrumental to decipher the role of the genes encoding secreted effectors necessary for parasitism and genes attributed to normal development. Recent comparative and functional genomic approaches have accelerated the identification of effectors from phytoparasitic nematodes and offers opportunities to control these pathogens.

CONCLUSION

Plant parasitic nematodes pose a serious threat to global food security of various economically important crops. There is a wealth of genomic and transcriptomic information available on plant parasitic nematodes and comparative genomics has identified many effectors. Bioengineering crops with dsRNA of phytonematode genes can disrupt the life cycle of parasitic nematodes and therefore holds great promise to develop resistant crops against plant-parasitic nematodes.

Specification of anteroposterior axis by combinatorial signaling during Xenopus development

The specification of anteroposterior (AP) axis is a fundamental and complex patterning process that sets up the embryonic polarity and shapes a multicellular organism. This process involves the integration of distinct signaling pathways to coordinate temporal-spatial gene expression and morphogenetic movements. In the frog Xenopus, extensive embryological and molecular studies have provided major advance in understanding the mechanism implicated in AP patterning. Following fertilization, cortical rotation leads to the transport of maternal determinants to the dorsal region and creates the primary dorsoventral (DV) asymmetry. The activation of maternal Wnt/ß-catenin signaling and a high Nodal signal induces the formation of the Nieuwkoop center in the dorsal-vegetal cells, which then triggers the formation of the Spemann organizer in the overlying dorsal marginal zone. It is now well established that the Spemann organizer plays a central role in building the vertebrate body axes because it provides patterning information for both DV and AP polarities. The antagonistic interactions between signals secreted in the Spemann organizer and the opposite ventral region pattern the mesoderm along the DV axis, and this DV information is translated into AP positional values during gastrulation. The formation of anterior neural tissue requires simultaneous inhibition of zygotic Wnt and bone morphogenetic protein (BMP) signals, while an endogenous gradient of Wnt, fibroblast growth factors (FGFs), retinoic acid (RA) signaling, and collinearly expressed Hox genes patterns the trunk and posterior regions. Collectively, DV asymmetry is mostly coupled to AP polarity, and cell-cell interactions mediated essentially by the same regulatory networks operate in DV and AP patterning. For further resources related to this article, please visit the WIREs website.

Tumor Suppressor Lzap Suppresses Wnt/β-Catenin Signaling to Promote Zebrafish Embryonic Ventral Cell Fates via the Suppression of Inhibitory Phosphorylation of Glycogen Synthase Kinase 3

Wnt/β-catenin signaling controls various cell fates in metazoan development, and its dysregulation is often associated with cancer formation. However, regulations of this signaling pathway are not completely understood. Here, we report that Lzap, a tumor suppressor, controls nuclear translocation of β-catenin. In zebrafish embryos disruption of lzap increases the expression of chordin (chd), which encodes a bone morphogenetic protein (BMP) antagonist that is localized in prospective dorsal cells and promotes dorsal fates. Consistently, lzap-deficient embryos with attenuated BMP signaling are dorsalized, which can be rescued by overexpression of zebrafish lzap or bmp2b or human LZAP. The expansion of chd expression in embryos lacking lzap is due to the accumulation of nuclear β-catenin in ventral cells, in which β-catenin is usually degraded. Furthermore, the activity of GSK3, a master regulator of β-catenin degradation, is suppressed in lzap-deficient embryos via inhibitory phosphorylation. Finally, we also report that a similar regulatory axis is also likely to be present in a human tongue carcinoma cell line, SAS. Our results reveal that Lzap is a novel regulator of GSK3 for the maintenance of ventral cell properties and may prevent carcinogenesis via the regulation of β-catenin degradation.

Proteomics of Xenopus development

Modern mass spectrometry-based methods provide an exciting opportunity to characterize protein expression in the developing embryo. We have employed an isotopic labeling technology to quantify the expression dynamics of nearly 6000 proteins across six stages of development in Xenopus laevis from the single stage zygote through the mid-blastula transition and the onset of organogenesis. Approximately 40% of the proteins show significant changes in expression across the development stages. The expression changes for these proteins naturally falls into six clusters corresponding to major events that mark early Xenopus development. A subset of experiments in this study have quantified protein expression differences between single embryos at the same stage of development, showing that, within experimental error, embryos at the same developmental stage have identical protein expression levels.

A review of 18p deletions

Since 18p- was first described in 1963, much progress has been made in our understanding of this classic deletion condition. We have been able to establish a fairly complete picture of the phenotype when the deletion breakpoint occurs at the centromere, and we are working to establish the phenotypic effects when each gene on 18p is hemizygous. Our aim is to provide genotype-specific anticipatory guidance and recommendations to families with an 18p- diagnosis. In addition, establishing the molecular underpinnings of the condition will potentially suggest targets for molecular treatments. Thus, the next step is to establish the precise effects of specific gene deletions. As we look forward to deepening our understanding of 18p-, our focus will continue to be on the establishment of robust genotype-phenotype correlations and the penetrance of these phenotypes. We will continue to follow our 18p- cohort closely as they age to determine the presence or absence of some of these diagnoses, including spinocerebellar ataxia (SCA), facioscapulohumeral muscular dystrophy (FSHD), and dystonia. We will also continue to refine the critical regions for other phenotypes as we enroll additional (hopefully informative) participants into the research study and as the mechanisms of the genes in these regions are elucidated. Mouse models will also be developed to further our understanding of the effects of hemizygosity as well as to serve as models for treatment development.

Bone morphogenetic protein-4: a novel therapeutic target for pathological cardiac hypertrophy/heart failure

Bone morphogenetic protein-4 (BMP4) is a member of the bone morphogenetic protein family which plays a key role in the bone formation and embryonic development. In addition to these predominate and well-studied effects, the growing evidences highlight BMP4 as an important factor in cardiovascular diseases, such as hypertension, pulmonary hypertension and valve disease. Our recent works demonstrated that BMP4 mediated cardiac hypertrophy, apoptosis, fibrosis and ion channel remodeling in pathological cardiac hypertrophy. In this review, we discussed the role of BMP4 in pathological cardiac hypertrophy, as well as the recent advances about BMP4 in cardiovascular diseases closely related to pathological cardiac hypertrophy/heart failure. We put forward that BMP4 is a novel therapeutic target for pathological cardiac hypertrophy/heart failure.

Temporally coordinated signals progressively pattern the anteroposterior and dorsoventral body axes

The vertebrate body plan is established through the precise spatiotemporal coordination of morphogen signaling pathways that pattern the anteroposterior (AP) and dorsoventral (DV) axes. Patterning along the AP axis is directed by posteriorizing signals Wnt, fibroblast growth factor (FGF), Nodal, and retinoic acid (RA), while patterning along the DV axis is directed by bone morphogenetic proteins (BMP) ventralizing signals. This review addresses the current understanding of how Wnt, FGF, RA and BMP pattern distinct AP and DV cell fates during early development and how their signaling mechanisms are coordinated to concomitantly pattern AP and DV tissues.

Synthetic enzyme-substrate tethering obviates the Tolloid-ECM interaction during Drosophila BMP gradient formation

Members of the Tolloid family of metalloproteinases liberate BMPs from inhibitory complexes to regulate BMP gradient formation during embryonic dorsal-ventral axis patterning. Here, we determine mechanistically how Tolloid activity is regulated by its non-catalytic CUB domains in the Drosophila embryo. We show that Tolloid, via its N-terminal CUB domains, interacts with Collagen IV, which enhances Tolloid activity towards its substrate Sog, and facilitates Tsg-dependent stimulation of cleavage. In contrast, the two most C-terminal Tld CUB domains mediate Sog interaction to facilitate its processing as, based on our structural data, Tolloid curvature positions bound Sog in proximity to the protease domain. Having ascribed functions to the Tolloid non-catalytic domains, we recapitulate embryonic BMP gradient formation in their absence, by artificially tethering the Tld protease domain to Sog. Our studies highlight how the bipartite function of Tolloid CUB domains, in substrate and ECM interactions, fine-tune protease activity to a particular developmental context.

DOI:http://dx.doi.org/10.7554/eLife.05508.001

The body of an animal is a highly organised structure of tissues and organs that contain cells with specialised roles. To achieve this level of organisation, it is important that the cells in the embryo know their location and receive the correct instructions on how to develop, when to divide or move. Many animals are roughly symmetrical about an imaginary line that runs from their head to their tail; a developing embryo can provide its cells with information about their position along this head-to-tail axis and the axis that runs from its front to its back.

Setting up the front-to-back axis in the embryo involves a family of proteins called the bone morphogenetic proteins (or BMPs). These proteins can bind to other proteins that act as signals to provide instructions to cells. However, many of the BMPs are unable to perform this job because they are trapped by inhibitory molecules that bind to them instead.

Enzymes belonging to the Tolloid family can break down these inhibitors to release the BMPs. Together, the inhibitors and Tolloid enzymes create a gradient of BMP activity across the embryo. The side of the embryo with the highest levels of active BMPs sets the position of the back of the body, while the opposite side—which has the lowest levels of active BMPs—becomes the front. However, it is not clear how Tolloid is controlled to create the BMP gradient.

Different parts of the Tolloid enzyme have different roles; one portion of the enzyme breaks down the inhibitory molecules, and there are also several so-called ‘non-catalytic domains’. Winstanley et al. used a combination of approaches to study how Tolloid is controlled in fruit fly embryos. The experiments show that two non-catalytic domains at one end of Tolloid help the enzyme to bind to the inhibitory molecules. At the other end of the Tolloid enzyme, another non-catalytic domain can bind to a structural protein called Collagen IV. This enhances the ability of the enzyme to break down the inhibitory molecules and release the BMPs.

These findings reveal how Tolloid's non-catalytic domains can fine-tune the activity of this enzyme to create the gradient of BMP activity that is needed to set the front-to-back direction in animal embryos. Future studies will focus on identifying other proteins that bind to the non-catalytic domains of Tolloid in order to further control its activity during development.

DOI:http://dx.doi.org/10.7554/eLife.05508.002

Holoprosencephaly: signaling interactions between the brain and the face, the environment and the genes, and the phenotypic variability in animal models and humans

Holoprosencephaly (HPE) is the most common developmental defect of the forebrain characterized by inadequate or absent midline division of the forebrain into cerebral hemispheres, with concomitant midline facial defects in the majority of cases. Understanding the pathogenesis of HPE requires knowledge of the relationship between the developing brain and the facial structures during embryogenesis. A number of signaling pathways control and coordinate the development of the brain and face, including Sonic hedgehog, Bone morphogenetic protein, Fibroblast growth factor, and Nodal signaling. Mutations in these pathways have been identified in animal models of HPE and human patients. Because of incomplete penetrance and variable expressivity of HPE, patients carrying defined mutations may not manifest the disease at all, or have a spectrum of defects. It is currently unknown what drives manifestation of HPE in genetically at-risk individuals, but it has been speculated that other gene mutations and environmental factors may combine as cumulative insults. HPE can be diagnosed in utero by a high-resolution prenatal ultrasound or a fetal magnetic resonance imaging, sometimes in combination with molecular testing from chorionic villi or amniotic fluid sampling. Currently, there are no effective preventive methods for HPE. Better understanding of the mechanisms of gene-environment interactions in HPE would provide avenues for such interventions.

Nanoscale structure of the BMP antagonist chordin supports cooperative BMP binding

Bone morphogenetic proteins (BMPs) orchestrate key cellular events, such as proliferation and differentiation, in development and homeostasis. Extracellular antagonists, such as chordin, are essential regulators of BMP signaling. Chordin binds to BMPs blocking interaction with receptors, and cleavage by tolloid proteinases is thought to relieve this inhibition. A model has been previously proposed where chordin adopts a horseshoe-like arrangement enabling BMP binding cooperatively by terminal domains (1). Here, we present the nanoscale structure of human chordin using electron microscopy, small angle X-ray scattering, and solution-based biophysical techniques, which together show that chordin indeed has a compact horseshoe-shaped structure. Chordin variants were used to map domain locations within the chordin molecule. The terminal BMP-binding domains protrude as prongs from the main body of the chordin structure, where they are well positioned to interact with the growth factor. The spacing provided by the chordin domains supports the principle of a cooperative BMP-binding arrangement that the original model implied in which growth factors bind to both an N- and C-terminal von Willebrand factor C domain of chordin. Using binding and bioactivity assays, we compared full-length chordin with two truncated chordin variants, such as those produced by partial tolloid cleavage. Cleavage of either terminal domain has little effect on the affinity of chordin for BMP-4 and BMP-7 but C-terminal cleavage increases the efficacy of chordin as a BMP-4 inhibitor. Together these data suggest that partial tolloid cleavage is insufficient to ablate BMP inhibition and the C-terminal chordin domains play an important role in BMP regulation.

Diversity is in my veins: role of bone morphogenetic protein signaling during venous morphogenesis in zebrafish illustrates the heterogeneity within endothelial cells

Endothelial cells are a highly diverse group of cells which display distinct cellular responses to exogenous stimuli. Although the aptly named vascular endothelial growth factor-A signaling pathway is hailed as the most important signaling input for endothelial cells, additional factors also participate in regulating diverse aspects of endothelial behaviors and functions. Given this heterogeneity, these additional factors seem to play a critical role in creating a custom-tailored environment to regulate behaviors and functions of distinct subgroups of endothelial cells. For instance, molecular cues that modulate morphogenesis of arterial vascular beds can be distinct from those that govern morphogenesis of venous vascular beds. Recently, we have found that bone morphogenetic protein signaling selectively promotes angiogenesis from venous vascular beds without eliciting similar responses from arterial vascular beds in zebrafish, indicating that bone morphogenetic protein signaling functions as a context-dependent regulator during vascular morphogenesis. In this review, we will provide an overview of the molecular mechanisms that underlie proangiogenic effects of bone morphogenetic protein signaling on venous vascular beds in the context of endothelial heterogeneity and suggest a more comprehensive picture of the molecular mechanisms of vascular morphogenesis during development.

Quantitative proteomics of Xenopus laevis embryos: expression kinetics of nearly 4000 proteins during early development

While there is a rich literature on transcription dynamics during the development of many organisms, protein data is limited. We used iTRAQ isotopic labeling and mass spectrometry to generate the largest developmental proteomic dataset for any animal. Expression dynamics of nearly 4,000 proteins of Xenopuslaevis was generated from fertilized egg to neurula embryo. Expression clusters into groups. The cluster profiles accurately reflect the major events that mark changes in gene expression patterns during early Xenopus development. We observed decline in the expression of ten DNA replication factors after the midblastula transition (MBT), including a marked decline of the licensing factor XCdc6. Ectopic expression of XCdc6 leads to apoptosis; temporal changes in this protein are critical for proper development. Measurement of expression in single embryos provided no evidence for significant protein heterogeneity between embryos at the same stage of development.

Twisted gastrulation, a BMP antagonist, exacerbates podocyte injury

Podocyte injury is the first step in the progression of glomerulosclerosis. Previous studies have demonstrated the beneficial effect of bone morphogenetic protein 7 (Bmp7) in podocyte injury and the existence of native Bmp signaling in podocytes. Local activity of Bmp7 is controlled by cell-type specific Bmp antagonists, which inhibit the binding of Bmp7 to its receptors. Here we show that the product of Twisted gastrulation (Twsg1), a Bmp antagonist, is the central negative regulator of Bmp function in podocytes and that Twsg1 null mice are resistant to podocyte injury. Twsg1 was the most abundant Bmp antagonist in murine cultured podocytes. The administration of Bmp induced podocyte differentiation through Smad signaling, whereas the simultaneous administration of Twsg1 antagonized the effect. The administration of Bmp also inhibited podocyte proliferation, whereas simultaneous administration of Twsg1 antagonized the effect. Twsg1 was expressed in the glomerular parietal cells (PECs) and distal nephron of the healthy kidney, and additionally in damaged glomerular cells in a murine model of podocyte injury. Twsg1 null mice exhibited milder hypoalbuminemia and hyperlipidemia, and milder histological changes while maintaining the expression of podocyte markers during podocyte injury model. Taken together, our results show that Twsg1 plays a critical role in the modulation of protective action of Bmp7 on podocytes, and that inhibition of Twsg1 is a promising means of development of novel treatment for podocyte injury.

Mechanisms of scaling in pattern formation

Many organisms and their constituent tissues and organs vary substantially in size but differ little in morphology; they appear to be scaled versions of a common template or pattern. Such scaling involves adjusting the intrinsic scale of spatial patterns of gene expression that are set up during development to the size of the system. Identifying the mechanisms that regulate scaling of patterns at the tissue, organ and organism level during development is a longstanding challenge in biology, but recent molecular-level data and mathematical modeling have shed light on scaling mechanisms in several systems, including Drosophila and Xenopus. Here, we investigate the underlying principles needed for understanding the mechanisms that can produce scale invariance in spatial pattern formation and discuss examples of systems that scale during development.

Chromosome 18p deletion syndrome presenting holoprosencephaly and premaxillary agenesis: prenatal diagnosis and aCGH characterization using uncultured amniocytes

We present prenatal diagnosis of a de novo distal 18p deletion involving 14.06Mb at 18p11.32-p11.21 by aCGH using uncultured amniocytes in a pregnancy with fetal holoprosencephaly and premaxillary agenesis. QF-PCR analysis showed that distal 18p deletion was from maternal origin. Metaphase FISH analysis confirmed haploinsufficiency of TGIF. We discuss the functions of the genes that are deleted within this region. The present case shows the usefulness of applying aCGH on uncultured amniocytes for rapid aneuploidy diagnosis in cases with prenatally detected fetal structural abnormalities.

SILAC-based quantitative proteomic analysis of gastric cancer secretome

PURPOSE

Gastric cancer is a commonly occurring cancer in Asia and one of the leading causes of cancer deaths. However, there is no reliable blood-based screening test for this cancer. Identifying proteins secreted from tumor cells could lead to the discovery of clinically useful biomarkers for early detection of gastric cancer.

EXPERIMENTAL DESIGN

A SILAC-based quantitative proteomic approach was employed to identify secreted proteins that were differentially expressed between neoplastic and non-neoplastic gastric epithelial cells. Proteins from the secretome were subjected to SDS-PAGE and SCX-based fractionation, followed by mass spectrometric analysis on an LTQ-Orbitrap Velos mass spectrometer. Immunohistochemical labeling was employed to validate a subset of candidates using tissue microarrays.

RESULTS

We identified 2205 proteins in the gastric cancer secretome of which 263 proteins were overexpressed greater than fourfold in gastric cancer-derived cell lines as compared to non-neoplastic gastric epithelial cells. Three candidate proteins, proprotein convertase subtilisin/kexin type 9 (PCSK9), lectin mannose binding 2 (LMAN2), and PDGFA-associated protein 1 (PDAP1) were validated by immunohistochemical labeling.

CONCLUSIONS AND CLINICAL RELEVANCE

We report here the largest cancer secretome described to date. The novel biomarkers identified in the current study are excellent candidates for further testing as early detection biomarkers for gastric adenocarcinoma.

Antagonism and synergy between extracellular BMP modulators Tsg and BMPER balance blood vessel formation

Growth and regeneration of blood vessels are crucial processes during embryonic development and in adult disease. Members of the bone morphogenetic protein (BMP) family are growth factors known to play a key role in vascular development. The BMP pathway is controlled by extracellular BMP modulators such as BMP endothelial cell precursor derived regulator (BMPER), which we reported previously acts proangiogenically on endothelial cells in a concentration-dependent manner. Here, we explore the function of other BMP modulators, especially Tsg, on endothelial cell behaviour and compare them to BMPER. In Matrigel assays, BMP modulators chordin and noggin had no stimulatory effect; however, gremlin and Tsg enhanced human umbilical vein endothelial cell (HUVEC) sprouting. As the activation dynamics of Tsg were similar to those of BMPER, we further investigated the proangiogenic effect of Tsg on endothelial cells. Tsg enhanced endothelial cell ingrowth in the mouse Matrigel plug assay as well as HUVEC sprouting, migration and proliferation in vitro, dependent on Akt, Erk and Smad signalling pathway activation in a concentration-dependent manner. Surprisingly, silencing of Tsg also increased HUVEC sprouting, migration and proliferation, which is again associated with Akt, Erk and Smad signalling pathway activation. Furthermore, we reveal that Tsg and BMPER interfere with each other to enhance proangiogenic events. However, in vivo the presence of Tsg as well as of BMPER is mandatory for regular development of the zebrafish vasculature. Taken together, our results suggest that BMPER and Tsg maintain a fine-tuned equilibrium that controls BMP pathway activity and is necessary for vascular cell homeostasis.