Genome-wide investigation of the TGF-β superfamily in scallops

BACKGROUND

Transforming growth factor β (TGF-β) superfamily genes can regulate various processes, especially in embryogenesis, adult development, and homeostasis. To understand the evolution and divergence patterns of the TGF-β superfamily in scallops, genome-wide data from the Bay scallop (Argopecten irradians), the Zhikong scallop (Chlamys farreri) and the Yesso scallop (Mizuhopecten yessoensis) were systematically analysed using bioinformatics methods.

RESULTS

Twelve members of the TGF-β superfamily were identified for each scallop. The phylogenetic tree showed that these genes were grouped into 11 clusters, including BMPs, ADMP, NODAL, GDF, activin/inhibin and AMH. The number of exons and the conserved motif showed some differences between different clusters, while genes in the same cluster exhibited high similarity. Selective pressure analysis revealed that the TGF-β superfamily in scallops was evolutionarily conserved. The spatiotemporal expression profiles suggested that different TGF-β members have distinct functions. Several BMP-like and NODAL-like genes were highly expressed in early developmental stages, patterning the embryonic body plan. GDF8/11-like genes showed high expression in striated muscle and smooth muscle, suggesting that these genes may play a critical role in regulating muscle growth. Further analysis revealed a possible duplication of AMH, which played a key role in gonadal growth/maturation in scallops. In addition, this study found that several genes were involved in heat and hypoxia stress in scallops, providing new insights into the function of the TGF-β superfamily.

CONCLUSION

Characteristics of the TGF-β superfamily in scallops were identified, including sequence structure, phylogenetic relationships, and selection pressure. The expression profiles of these genes in different tissues, at different developmental stages and under different stresses were investigated. Generally, the current study lays a foundation for further study of their pleiotropic biological functions in scallops.

Characterization of the molecular mechanisms that govern anti-Müllerian hormone synthesis and activity

The roles of anti-Müllerian hormone (AMH) continue to expand, from its discovery as a critical factor in sex determination, through its identification as a regulator of ovarian folliculogenesis, its use in fertility clinics as a measure of ovarian reserve, and its emerging role in hypothalamic-pituitary function. In light of these actions, AMH is considered an attractive therapeutic target to address diverse reproductive needs, including fertility preservation. Here, we set out to characterize the molecular mechanisms that govern AMH synthesis and activity. First, we enhanced the processing of the AMH precursor to >90% by introducing more efficient proprotein convertase cleavage sites (RKKR or ISSRKKRSVSS [SCUT]). Importantly, enhanced processing corresponded with a dramatic increase in secreted AMH activity. Next, based on species differences across the AMH type II receptor-binding interface, we generated a series of human AMH variants and assessed bioactivity. AMHSCUT potency (EC50 4 ng/mL) was increased 5- or 10-fold by incorporating Gln484 Met/Leu535 Thr (EC50 0.8 ng/mL) or Gln484 Met/Gly533 Ser (EC50 0.4 ng/mL) mutations, respectively. Furthermore, the Gln484 Met/Leu535 Thr double mutant displayed enhanced efficacy, relative to AMHSCUT . Finally, we identified residues within the wrist pre-helix of AMH (Trp494 , Gln496 , Ser497 , and Asp498 ) that likely mediate type I receptor binding. Mutagenesis of these residues generated gain- (Trp494 Phe or Gln496 Leu) or loss- (Ser497 Ala) of function AMH variants. Surprisingly, combining activating type I and type II receptor mutations only led to modest additive increases in AMH potency/efficacy. Our study is the first to characterize AMH residues involved in type I receptor binding and suggests a step-wise receptor-complex assembly mechanism, in which enhancement in the affinity of the ligand for either receptor can increase AMH activity beyond the natural level.

Transcriptional profiles of TGF-β superfamily members in the lumbar DRGs and the effects of activins A and C on inflammatory pain in rats

Signaling by the transforming growth factor (TGF)-β superfamily is necessary for proper neural development and is involved in pain processing under both physiological and pathological conditions. Sensory neurons that reside in the dorsal root ganglia (DRGs) initially begin to perceive noxious signaling from their innervating peripheral target tissues and further convey pain signaling to the central nervous system. However, the transcriptional profile of the TGF-β superfamily members in DRGs during chronic inflammatory pain remains elusive. We developed a custom microarray to screen for transcriptional changes in members of the TGF-β superfamily in lumbar DRGs of rats with chronic inflammatory pain and found that the transcription of the TGF-β superfamily members tends to be downregulated. Among them, signaling of the activin/inhibin and bone morphogenetic protein/growth and differentiation factor (BMP/GDF) families dramatically decreased. In addition, peripherally pre-local administration of activins A and C worsened formalin-induced acute inflammatory pain, whereas activin C, but not activin A, improved formalin-induced persistent inflammatory pain by inhibiting the activation of astrocytes. This is the first report of the TGF-β superfamily transcriptional profiles in lumbar DRGs under chronic inflammatory pain conditions, in which transcriptional changes in cytokines or pathway components were found to contribute to, or be involved in, inflammatory pain processing. Our data will provide more targets for pain research.

Unveiling the transcriptomic landscape and the potential antagonist feedback mechanisms of TGF-β superfamily signaling module in bone and osteoporosis

BACKGROUND

TGF-β superfamily signaling is indispensable for bone homeostasis. However, the global expression profiles of all the genes that make up this signaling module in bone and bone-related diseases have not yet been well characterized.

METHODS

Transcriptomic datasets from human bone marrows, bone marrow-derived mesenchymal stem cells (MSCs) and MSCs of primary osteoporotic patients were used for expression profile analyses. Protein treatments, gene quantification, reporter assay and signaling dissection in MSC lines were used to clarify the interactive regulations and feedback mechanisms between TGF-β superfamily ligands and antagonists. Ingenuity Pathway Analysis was used for network construction.

RESULTS

We identified TGFB1 in the ligand group that carries out SMAD2/3 signaling and BMP8A, BMP8B and BMP2 in the ligand group that conducts SMAD1/5/8 signaling have relatively high expression levels in normal bone marrows and MSCs. Among 16 antagonist genes, the dominantly expressed TGF-β superfamily ligands induced only NOG, GREM1 and GREM2 via different SMAD pathways in MSCs. These induced antagonist proteins further showed distinct antagonisms to the treated ligands and thus would make up complicated negative feedback networks in bone. We further identified TGF-β superfamily signaling is enriched in MSCs of primary osteoporosis. Enhanced expression of the genes mediating TGF-β-mediated SMAD3 signaling and the genes encoding TGF-β superfamily antagonists served as significant features to osteoporosis.

CONCLUSION

Our data for the first time unveiled the transcription landscape of all the genes that make up TGF-β superfamily signaling module in bone. The feedback mechanisms and regulatory network prediction of antagonists provided novel hints to treat osteoporosis. Video Abstract.

Prognostic impact of activin subunit inhibin beta A in gastric and esophageal adenocarcinomas

PURPOSE

Adenocarcinomas of the esophagus (AEG) and stomach (AS) are among the most common cancers worldwide. Novel markers for risk stratification and guiding treatment are strongly needed. Activin is a multi-functional cytokine with context specific pro- and anti-tumorigenic effects. We aimed to investigate the prognostic role of activin tumor protein expression in AEG/ASs.

METHODS

Tissue from a retrospective cohort of 277 patients with AEG/AS treated primarily by surgery at the Charité - Universitätsmedizin Berlin was collected and analyzed by immunohistochemistry using a specific antibody to the activin homodimer inhibin beta A. Additionally, we evaluated T-cell infiltration and PD1 expression as well as expression of PD-L1 by immunohistochemistry as possible confounding factors. Clinico-pathologic data were collected and correlated with activin protein expression.

RESULTS

Out of 277 tumor samples, 72 (26.0%) exhibited high activin subunit inhibin beta A protein expression. Higher expression was correlated with lower Union for International Cancer Control (UICC) stage and longer overall survival. Interestingly, activin subunit expression correlated with CD4+ T-cell infiltration, and the correlation with higher overall survival was exclusively seen in tumors with high CD4+ T-cell infiltration, pointing towards a role of activin in the tumor immune response in AEG/ASs.

CONCLUSION

In our cohort of AEG/AS, higher activin subunit levels were correlated with longer overall survival, an effect exclusively seen in tumors with high CD4+ cell infiltration. Further mechanistic research is warranted discerning the exact effect of this context specific cytokine.

Dysregulated BMP2 in the Placenta May Contribute to Early-Onset Preeclampsia by Regulating Human Trophoblast Expression of Extracellular Matrix and Adhesion Molecules

Many pregnancy disorders, including early-onset preeclampsia (EOPE), are associated with defects in placental trophoblast cell invasion and differentiation during early placental development. Bone morphogenetic protein 2 (BMP2) belongs to the TGF-β superfamily and controls various physiological and developmental processes. However, the expression of BMP2 in the placenta and underlying molecular mechanisms of how BMP2 regulates trophoblast function remain unclear. In this study, we analyzed several publicly available microarray and RNA-seq datasets and revealed differences in expression of TGF-β superfamily members between gestational age-matched non-preeclamptic control and EOPE placentas. Importantly, BMP2 levels were significantly reduced in EOPE placentas compared with controls, and RNAscope in situ hybridization further demonstrated BMP2 expression was disrupted in EOPE placental villi. To explore the molecular mechanisms of BMP2-regulated early trophoblast differentiation, we examined BMP2 expression in first-trimester human placenta and found it to be localized to all subtypes of trophoblasts and the decidua. RNA-seq analysis on control and BMP2-treated primary human trophoblast cells identified 431 differentially expressed genes, including several canonical TGF-β/BMP signaling targets (BAMBI, ID1, INHBA, IGFBP3). Gene ontology annotations revealed that differentially expressed genes were involved in cell adhesion and extracellular matrix organization. Furthermore, we identified adhesion molecule with IgG-like domain 2 (AMIGO2) as a novel target for BMP2 that contributed to BMP2-induced trophoblast invasion and endothelial-like tube formation. Overall, our findings provide insight into the molecular processes controlled by BMP2 during early placental development that may contribute to the pathogenesis of EOPE.

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.

Roles of TGF-β Superfamily Proteins in Extravillous Trophoblast Invasion

Following embryo implantation, extravillous trophoblasts (EVTs) invade the maternal decidua to a certain extent during early pregnancy, which is critical for normal placentation and successful pregnancy in humans. Although sharing a similar protein structure, the transforming growth factor-β (TGF-β) superfamily members exert divergent functions in regulating EVT invasion, which contributes to a relative balance of TGF-β superfamily proteins in precisely modulating this process at the maternal-fetal interface during the first trimester of pregnancy. This review details recent advances in our understanding of the functions of TGF-β superfamily members and their corresponding receptors, signaling pathways, and downstream molecular targets in regulating human EVT invasion from studies using various in vitro or ex vivo experimental models. Also, the relevance of these discoveries about TGF-β superfamily members to adverse pregnancy outcomes is summarized. The application of 3D culture trophoblast organoids, single-cell sequencing, and microfluidic assays in EVT invasion studies will help better reveal the molecular mechanisms through which TGF-β superfamily members regulate human EVT invasion, shedding light on the development of innovative strategies for predicting, diagnosing, treating, and preventing adverse human pregnancy outcomes related to EVT invasion dysfunction.

The GDF15-GFRAL Pathway in Health and Metabolic Disease: Friend or Foe?

GDF15 is a cell activation and stress response cytokine of the glial cell line-derived neurotrophic factor family within the TGF-β superfamily. It acts through a recently identified orphan member of the GFRα family called GFRAL and signals through the Ret coreceptor. Cell stress and disease lead to elevated GDF15 serum levels, causing anorexia, weight loss, and alterations to metabolism, largely by actions on regions of the hindbrain. These changes restore homeostasis and, in the case of obesity, cause a reduction in adiposity. In some diseases, such as advanced cancer, serum GDF15 levels can rise by as much as 10-100-fold, leading to an anorexia-cachexia syndrome, which is often fatal. This review discusses how GDF15 regulates appetite and metabolism, the role it plays in resistance to obesity, and how this impacts diseases such as diabetes, nonalcoholic fatty liver disease, and anorexia-cachexia syndrome. It also discusses potential therapeutic applications of targeting the GDF15-GFRAL pathway and lastly suggests some potential unifying hypotheses for its biological role.

Characterization and immune function of decapentaplegic (Dpp) gene from the oriental river prawn, Macrobrachium nipponense

The Decapentaplegic (Dpp) gene, which belongs to the TGF-β superfamily, is involved in multiple developmental processes in eukaryotic species. In this study, we firstly identified and characterized Dpp from Macrobrachium nipponense. Its full-length open reading frame (ORF) cDNA was 1332 bp, encoding 443 amino acids. The putative MnDpp protein contained a signal peptide, a TGF-β propeptide region and a TGF-β domain. Its TGF-β domain was highly conserved from vertebrates to invertebrates, and exhibited highly similarity to Dpp derived from Bombyx mori. qRT-PCR analysis suggested that MnDpp expressed in all tested tissues and responded to both bacterial and virus pathogens, indicating MnDpp was involved in the innate immune response of M. nipponense. Knockdown of MnDppin vivo significantly increased bacteria growth and markedly decreased the expressions of NF-κB signaling genes including dorsal, relish, TAK1, TAB1, Ikkβ and Ikkε as well as antimicrobial peptides (AMPs) including ALF2, ALF3, ALF4, ALF5, Cru1 and Cru2. Moreover, in vitro overexpression of MnDpp protein in HEK293T cells further demonstrated that it exerted antibacterial immune response by activation of NF-κB signaling cascade. In summary, these results indicated that MnDpp played an important role in the innate immunity in M. nipponense by modulating NF-κB signaling pathway, which might provide new insights about Dpp in crustaceans and paved the way for a better understanding of the crustacean innate immune system.

Chondrodysplasias and Aneurysmal Thoracic Aortopathy: An Emerging Tale of Molecular Intersection

Although at first glance chondrodysplasia and aneurysmal thoracic aortopathy seem oddly dissimilar, recent lines of evidences indicate that they share molecular similarities. Chondrodysplasias are a group of skeletal disorders characterized by genetic defects in hyaline cartilage. Aneurysmal thoracic aortopathy is the pathological enlargement of the thoracic aorta due to wall weakness, along with its ensuing life-threatening complications (i.e., aortic dissection and/or rupture). Extracellular matrix dysregulation, abnormal TGF-β signaling, and, to a more limited extent, endoplasmic reticulum stress emerge as common disease processes. In this review we provide a comprehensive overview of the genetic and pathomechanistic overlap as well as of how these commonalities can guide treatment strategies for both disease entities.

BMP Signaling in Development, Stem Cells, and Diseases of the Gastrointestinal Tract

The bone morphogenetic protein (BMP) pathway is essential for the morphogenesis of multiple organs in the digestive system. Abnormal BMP signaling has also been associated with disease initiation and progression in the gastrointestinal (GI) tract and associated organs. Recent studies using animal models, tissue organoids, and human pluripotent stem cells have significantly expanded our understanding of the roles played by BMPs in the development and homeostasis of GI organs. It is clear that BMP signaling regulates GI function and disease progression that involve stem/progenitor cells and inflammation in a tissue-specific manner. In this review we discuss these new findings with a focus on the esophagus, stomach, and intestine.

The Activin-like ligand Dawdle regulates innate immune responses through modulating NF-κB signaling in mud crab Scylla paramamosain

Activins, members of transforming growth factor β (TGF-β) superfamily, are pleiotropic cytokines with critical roles in mediating cell proliferation, differentiation, homeostasis, apoptosis and immune response. However, the structural characteristics and specific functions of Activins remain largely unknown in invertebrates. In the present study, an Activin-like ligand Dawdle (Daw) was firstly identified and characterized from mud crab Scylla paramamosain. The obtained cDNA sequence of SpDaw was 2, 196 bp long with a 1, 149 bp open reading fame, which encoded a putative protein of 382 amino acids. The putative SpDaw protein contained a signal peptide, a TGF-β propeptide region and a TGF-β domain. Real-time PCR analysis demonstrated that SpDaw was predominantly expressed at early embryonic development stage and premolt stages, implying its participation in development and growth. Furthermore, SpDaw responded to both Vibro alginolyticus and Poly (I:C) challenges, suggesting the involvement of SpDaw in innate immune responses. Knockdown of SpDaw in vivo dramatically increased the expressions of NF-κB signaling genes and anti-lipopolysaccharide factor (ALF) genes, and the bacteria clearance efficiency was also markedly enhanced in SpDaw-silenced crabs. Moreover, the in vitro experiment further demonstrated that recombinant SpDaw protein could block the increased transcription of IKKs, NF-κBs and ALFs induced by pathogen challenges. Taken together, these results indicated that SpDaw not only participated in development and growth processes but also played an immune-regulatory role in crabs' innate immunity, which may pave the way for a better understanding of TGF-β superfamily members in crustacean species.

Allergen-induced asthma, chronic rhinosinusitis and transforming growth factor-β superfamily signaling: mechanisms and functional consequences

Introduction: Often co-associated, asthma and chronic rhinosinusitis (CRS) are complex heterogeneous disease syndromes. Severity in both is related to tissue inflammation and abnormal repair (termed remodeling). Understanding signaling factors that can modulate, integrate the activation, and regulation of such key processes together is increasingly important. The transforming growth factor (TGF)-β superfamily of ligands comprise a versatile system of immunomodulatory molecules that are gaining recognition as having an essential function in the immunopathogenesis of asthma. Early data suggest an important role in CRS as well. Abnormal or dysregulated signaling may contribute to disease pathogenesis and severity.Areas covered: The essential biology of this complex family of growth factors in relation to the excess inflammation and remodeling that occurs in allergic asthma and CRS is reviewed. The need to understand the integration of signaling pathways together is highlighted. Studies in human airway tissue are evaluated and only selected key animal models relevant to human disease discussed given the highly context-dependent signaling and function of these ligands.Expert opinion: Abnormal or dysregulated TGF-β superfamily signaling may be central to the excess inflammation and tissue remodeling in asthma, and possibly CRS. Therefore, the TGF-β superfamily signaling pathways represent an emerging and attractive therapeutic target.

Structural characterization of an activin class ternary receptor complex reveals a third paradigm for receptor specificity

TGFβ family ligands, which include the TGFβs, BMPs, and activins, signal by forming a ternary complex with type I and type II receptors. For TGFβs and BMPs, structures of ternary complexes have revealed differences in receptor assembly. However, structural information for how activins assemble a ternary receptor complex is lacking. We report the structure of an activin class member, GDF11, in complex with the type II receptor ActRIIB and the type I receptor Alk5. The structure reveals that receptor positioning is similar to the BMP class, with no interreceptor contacts; however, the type I receptor interactions are shifted toward the ligand fingertips and away from the dimer interface. Mutational analysis shows that ligand type I specificity is derived from differences in the fingertips of the ligands that interact with an extended loop specific to Alk4 and Alk5. The study also reveals differences for how TGFβ and GDF11 bind to the same type I receptor, Alk5. For GDF11, additional contacts at the fingertip region substitute for the interreceptor interactions that are seen for TGFβ, indicating that Alk5 binding to GDF11 is more dependent on direct contacts. In support, we show that a single residue of Alk5 (Phe⁸⁴), when mutated, abolishes GDF11 signaling, but has little impact on TGFβ signaling. The structure of GDF11/ActRIIB/Alk5 shows that, across the TGFβ family, different mechanisms regulate type I receptor binding and specificity, providing a molecular explanation for how the activin class accommodates low-affinity type I interactions without the requirement of cooperative receptor interactions.

Bioreactor-Controlled Physoxia Regulates TGF-β Signaling to Alter Extracellular Matrix Synthesis by Human Chondrocytes

Culturing articular chondrocytes under physiological oxygen tension exerts positive effects on their extracellular matrix synthesis. The underlying molecular mechanisms which enhance the chondrocytic phenotype are, however, still insufficiently elucidated. The TGF-β superfamily of growth factors, and the prototypic TGF-β isoforms in particular, are crucial in maintaining matrix homeostasis of these cells. We employed a feedback-controlled table-top bioreactor to investigate the role of TGF-β in microtissues of human chondrocytes over a wider range of physiological oxygen tensions (i.e., physoxia). We compared 1%, 2.5%, and 5% of partial oxygen pressure (pO₂) to the ‘normoxic’ 20%. We confirmed physoxic conditions through the induction of marker genes (PHD3, VEGF) and oxygen tension-dependent chondrocytic markers (SOX9, COL2A1). We identified 2.5% pO₂ as an oxygen tension optimally improving chondrocytic marker expression (ACAN, COL2A1), while suppressing de-differentiation markers (COL1A1,COL3A1). Expression of TGF-β isoform 2 (TGFB2) was, relatively, most responsive to 2.5% pO₂, while all three isoforms were induced by physoxia. We found TGF-β receptors ALK1 and ALK5 to be regulated by oxygen tension on the mRNA and protein level. In addition, expression of type III co-receptors betaglycan and endoglin appeared to be regulated by oxygen tension as well. R-Smad signaling confirmed that physoxia divergently regulated phosphorylation of Smad1/5/8 and Smad2/3. Pharmacological inhibition of canonical ALK5-mediated signaling abrogated physoxia-induced COL2A1 and PAI-1 expression. Physoxia altered expression of hypertrophy markers and that of matrix metalloproteases and their activity, as well as expression ratios of specific proteins (Sp)/Krüppel-like transcription factor family members SP1 and SP3, proving a molecular concept of ECM marker regulation. Keeping oxygen levels tightly balanced within a physiological range is important for optimal chondrocytic marker expression. Our study provides novel insights into transcriptional regulations in chondrocytes under physoxic in vitro conditions and may contribute to improving future cell-based articular cartilage repair strategies.

Increased TGF-β and BMP Levels and Improved Chondrocyte-Specific Marker Expression In Vitro under Cartilage-Specific Physiological Osmolarity

During standard expansion culture (i.e., plasma osmolarity, 280 mOsm) human articular chondrocytes dedifferentiate, making them inappropriate for autologous chondrocyte implantation to treat cartilage defects. Increasing the osmolarity of culture media to physiological osmolarity levels of cartilage (i.e., 380 mOsm), increases collagen type II (COL2A1) expression of human articular chondrocytes in vitro, but the underlying molecular mechanism is not fully understood. We hypothesized that TGF-β superfamily signaling may drive expression of COL2A1 under physiological osmolarity culture conditions. Human articular chondrocytes were cultured in cytokine-free medium of 280 or 380 mOsm with or without siRNA mediated TGF-β2 knockdown (RNAi). Expression of TGF-β isoforms, and collagen type II was evaluated by RT-qPCR and immunoblotting. TGF-β2 protein secretion was evaluated using ELISA and TGF-β bioactivity was determined using an established reporter assay. Involvement of BMP signaling was investigated by culturing human articular chondrocytes in the presence or absence of BMP inhibitor dorsomorphin and BMP bioactivity was determined using an established reporter assay. Physiological cartilage osmolarity (i.e., physosmolarity) most prominently increased TGF-β2 mRNA expression and protein secretion as well as TGF-β bioactivity. Upon TGF-β2 isoform-specific knockdown, gene expression of chondrocyte marker COL2A1 was induced. TGF-β2 RNAi under physosmolarity enhanced TGF-β bioactivity. BMP bioactivity increased upon physosmotic treatment, but was not related to TGF-β2 RNAi. In contrast, dorsomorphin inhibited COL2A1 mRNA expression in human articular chondrocytes independent of the osmotic condition. Our data suggest a role for TGF-β superfamily member signaling in physosmolarity-induced mRNA expression of collagen type II. As physosmotic conditions favor the expression of COL2A1 independent of our manipulations, contribution of other metabolic, post-transcriptional or epigenetic factors cannot be excluded in the underlying complex and interdependent regulation of marker gene expression. Dissecting these molecular mechanisms holds potential to further improve future cell-based chondral repair strategies.

Spatial regulation of gene expression in nonsyndromic sagittal craniosynostosis

OBJECTIVECranial suture patterning and development are highly regulated processes that are not entirely understood. While studies have investigated the differential gene expression for different sutures, little is known about gene expression changes during suture fusion. The aim of this study was to examine gene expression in patent, fusing, and fused regions along sagittal suture specimens in nonsyndromic craniosynostosis patients.METHODSSagittal sutures were collected from 7 patients (average age 4.5 months) who underwent minimally invasive craniotomies at the Children's Hospital of Richmond at VCU under IRB approval. The sutures were analyzed using micro-CT to evaluate patency. The areas were classified as open, fusing, or fused and were harvested, and mRNA was isolated. Gene expression for bone-related proteins, osteogenic and angiogenic factors, transforming growth factor-β (TGF-β) superfamily, and Wnt signaling was analyzed using quantitative polymerase chain reaction and compared with normal sutures collected from fetal demise tissue (control).RESULTSMicro-CT demonstrated that there are variable areas of closure along the length of the sagittal suture. When comparing control samples to surgical samples, there was a significant difference in genes for Wnt signaling, TGF-β, angiogenic and osteogenic factors, bone remodeling, and nuclear rigidity in mRNA isolated from the fusing and fused areas of the sagittal suture compared with patent areas (p < 0.05).CONCLUSIONSIn nonsyndromic sagittal craniosynostosis, the affected suture has variable areas of being open, fusing, and fused. These specific areas have different mRNA expression. The results suggest that BMP-2, FGFR3, and several other signaling pathways play a significant role in the regulation of suture fusion as well as in the maintenance of patency in the normal suture.

Design, 3D QSAR modeling and docking of TGF-β type I inhibitors to target cancer

Transforming growth factor-β (TGF-β) family members plays a vital role in regulating hormonal function, bone formation, tissue remodeling, and erythropoiesis, cell growth and apoptosis. TGF-β super-family members mediate signal transduction via serine/threonine kinase receptors located on the cell membrane. Variation in expression of the TGF-β type I and II receptors in the cancer cells compromise its tumor suppressor activities which direct to oncogenic functions. The present study was aimed to screen the potent TGF-β type I inhibitors through atom based 3D-QSAR and pharmacophore modelling. For this purpose, we have chosen known TGF-β type I inhibitors from the binding database. The PHASE module of Schrodinger identified the best Pharmacophore model which includes three hydrogen bond acceptors (A), one hydrophobic region (H), and one ring (R) as the structural features. The top pharmacophore model AAAHR.27 was chosen with the R² value of 0.94 and validated externally using molecules of the test set. Moreover the AAAHR.27 model underwent virtual screening using the molecules from the NCI, ZINC and Maybridge database. The screened molecules were further filtered using molecular docking and ADME properties prediction. Additionally, the 7 lead molecules were compared with a newly identified compound "SB431542" (well known TGF-β type I receptor inhibitor) and Galunisertib, a small molecule inhibitor of TGF-β type I, under clinical development (phase II trials) using the docking score and other binding properties. Also a top scored screened molecule from our study has been compared and confirmed using molecular dynamic simulation studies. By this way, we have obtained 7 distinct drug-like TGF-β type I inhibitors which can be beneficial in suppressing cancers reported with up-regulation of TGF-β type I. This result highlights the guidelines for designing molecules with TGF-β Type I inhibitory properties.

Molecular Aspects and Clinical Relevance of GDF9 and BMP15 in Ovarian Function

Growth and differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) are oocyte-secreted factors with a leading role in the control of ovarian function in female reproduction, modulating both the cell fate of the somatic granulosa cells and the quality and developmental competence of the egg. This short review aims to consolidate the molecular aspects of GDF9 and BMP15 and their integral actions in female fertility to understand particularly their effects on oocyte quality and fetal growth. The significant consequences of mutations in the GDF9 and BMP15 genes in women with dizygotic twins as well as the clinical relevance of these oocyte factors in the pathogenesis of primary ovarian insufficiency and polycystic ovary syndrome are also addressed.

The emerging role of follistatin under stresses and its implications in diseases

Follistatin (FST), a single-chain glycosylated protein, is expressed in various tissues. The essential biological function of FST is binding and neutralizing transforming growth factor β (TGF-β) superfamily, including activin, myostatin, and bone morphogenetic protein (BMP). Emerging evidence indicates that FST also serves as a stress responsive protein, which plays a protective role under a variety of stresses. In most cases, FST performs the protective function through its neutralization of TGF-β superfamily. However, under certain circumstances, FST translocates into the nucleus to maintain cellular homeostasis independent of its extracellular antagonism activity. This review provides integrated insight into the most recent advances in understanding the role of FST under various stresses, and the clinical implications corresponding to these findings and discusses the mechanisms to be further studied.

Myostatin inhibitor ACE-031 treatment of ambulatory boys with Duchenne muscular dystrophy: Results of a randomized, placebo-controlled clinical trial

INTRODUCTION

ACE-031 is a fusion protein of activin receptor type IIB and IgG1-Fc, which binds myostatin and related ligands. It aims to disrupt the inhibitory effect on muscle development and provide potential therapy for myopathies like Duchenne muscular dystrophy (DMD).

METHODS

ACE-031 was administered subcutaneously every 2-4 weeks to DMD boys in a randomized, double-blind, placebo-controlled, ascending-dose trial. The primary objective was safety evaluation. Secondary objectives included characterization of pharmacokinetics and pharmacodynamics.

RESULTS

ACE-031 was not associated with serious or severe adverse events. The study was stopped after the second dosing regimen due to potential safety concerns of epistaxis and telangiectasias. A trend for maintenance of the 6-minute walk test (6MWT) distance in the ACE-031 groups compared with a decline in the placebo group (not statistically significant) was noted, as was a trend for increased lean body mass and bone mineral density (BMD) and reduced fat mass.

CONCLUSION

ACE-031 use demonstrated trends for pharmacodynamic effects on lean mass, fat mass, BMD, and 6MWT. Non-muscle-related adverse events contributed to the decision to discontinue the study. Myostatin inhibition is a promising therapeutic approach for DMD. Muscle Nerve 55: 458-464, 2017.

Conserved Anti-Müllerian Hormone: Anti-Müllerian Hormone Type-2 Receptor Specific Interaction and Intracellular Signaling in Teleosts

In higher vertebrates, anti-Müllerian hormone (AMH) is required for Müllerian duct regression in fetal males. AMH is also produced during postnatal life in both sexes regulating steroidogenesis and early stages of folliculogenesis. Teleosts lack Müllerian ducts, but Amh has been identified in several species including European sea bass. However, information on Amh type-2 receptor (Amhr2), the specific receptor for Amh binding, is restricted to a couple of fish species. Here, we report on cloning sea bass amhr2, the production of a recombinant sea bass Amh, and the functional analysis of this ligand-receptor couple. Phylogenetic analysis revealed that sea bass amhr2 segregates with Amhr2 from other vertebrates. This piscine receptor is capable of activating Smad proteins. Antibodies raised against sea bass Amh were used to study native and recombinant Amh, revealing proteins in the range of 66-70 kDa corresponding to the full length Amh. Once proteolytically treated, recombinant sea bass Amh generates a 12 kDa C-terminal mature protein, suggesting that contrary to what has been described for other fish Amh proteins, this protein is processed in a similar way as mammalian AMH. The mature sea bass Amh is a biologically active protein able to bind sea bass Amhr2 and, surprisingly, also human AMHR2. In prepubertal sea bass testes, Amh was detected by immunohistochemistry mostly in Sertoli cells surrounding early germ-cell generations. During spermatogenesis, a weaker staining signal could be observed in Sertoli cells surrounding spermatocytes.

Effect of N-Terminal Acylation on the Activity of Myostatin Inhibitory Peptides

Inhibition of myostatin, which negatively regulates skeletal muscle growth, is a promising strategy for the treatment of muscle atrophic disorders, such as muscular dystrophy, cachexia and sarcopenia. Recently, we identified peptide A (H-WRQNTRYSRIEAIKIQILSKLRL-NH2 ), the 23-amino-acid minimum myostatin inhibitory peptide derived from mouse myostatin prodomain, and highlighted the importance of its N-terminal tryptophan residue for the effective inhibition. In this study, we synthesized a series of acylated peptide derivatives focused on the tryptophan residue to develop potent myostatin inhibitors. As a result of the investigation, a more potent derivative of peptide A was successfully identified in which the N-terminal tryptophan residue is replaced with a 2-naphthyloxyacetyl moiety to give an inhibitory peptide three times (1.19±0.11 μm) more potent than parent peptide A (3.53±0.25 μm). This peptide could prove useful as a new starting point for the development of improved inhibitory peptides.

Inhibition of the myostatin/Smad signaling pathway by short decorin-derived peptides

Myostatin, also known as growth differentiation factor 8, is a member of the transforming growth factor-beta superfamily that has been shown to play a key role in the regulation of the skeletal muscle mass. Indeed, while myostatin deletion or loss of function induces muscle hypertrophy, its overexpression or systemic administration causes muscle atrophy. Since myostatin blockade is effective in increasing skeletal muscle mass, myostatin inhibitors have been actively sought after. Decorin, a member of the small leucine-rich proteoglycan family is a metalloprotein that was previously shown to bind and inactivate myostatin in a zinc-dependent manner. Furthermore, the myostatin-binding site has been shown to be located in the decorin N-terminal domain. In the present study, we investigated the anti-myostatin activity of short and soluble fragments of decorin. Our results indicate that the murine decorin peptides DCN48-71 and 42-65 are sufficient for inactivating myostatin in vitro. Moreover, we show that the interaction of mDCN48-71 to myostatin is strictly zinc-dependent. Binding of myostatin to activin type II receptor results in the phosphorylation of Smad2/3. Addition of the decorin peptide 48-71 decreased in a dose-dependent manner the myostatin-induced phosphorylation of Smad2 demonstrating thereby that the peptide inhibits the activation of the Smad signaling pathway. Finally, we found that mDCN48-71 displays a specificity towards myostatin, since it does not inhibit other members of the transforming growth factor-beta family.

TGF-β superfamily signaling in testis formation and early male germline development

The TGF-β ligand superfamily contains at least 40 members, many of which are produced and act within the mammalian testis to facilitate formation of sperm. Their progressive expression at key stages and in specific cell types determines the fertility of adult males, influencing testis development and controlling germline differentiation. BMPs are essential for the interactive instructions between multiple cell types in the early embryo that drive initial specification of gamete precursors. In the nascent foetal testis, several ligands including Nodal, TGF-βs, Activins and BMPs, serve as key masculinizing switches by regulating male germline pluripotency, somatic and germline proliferation, and testicular vascularization and architecture. In postnatal life, local production of these factors determine adult testis size by regulating Sertoli cell multiplication and differentiation, in addition to specifying germline differentiation and multiplication. Because TGF-β superfamily signaling is integral to testis formation, it affects processes that underlie testicular pathologies, including testicular cancer, and its potential to contribute to subfertility is beginning to be understood.

Constitutive negative regulation in the processing of the anti-Müllerian hormone receptor II

The levels and intracellular localization of wild-type transforming growth factor β superfamily (TGFβ-SF) receptors are tightly regulated by endocytic trafficking, shedding and degradation. In contrast, a main regulatory mechanism of mutation-bearing receptors involves their intracellular retention. Anti-Müllerian hormone receptor II (AMHRII, also known as AMHR2) is the type-II receptor for anti-Müllerian hormone (AMH), a TGFβ-SF ligand that mediates Müllerian duct regression in males. Here, we studied AMHRII processing and identified novel mechanisms of its constitutive negative regulation. Immunoblot analysis revealed that a significant portion of AMHRII was missing most of its extracellular domain (ECD) and, although glycosylated, was unfolded and retained in the endoplasmic reticulum. Exogenous expression of AMHRII, but not of type-II TGF-β receptor (TβRII, also known as TGFR2), resulted in its disulfide-bond-mediated homo-oligomerization and intracellular retention, and in a decrease in its AMH-binding capacity. At the plasma membrane, AMHRII differed from TβRII, forming high levels of non-covalent homomeric complexes, which exhibited a clustered distribution and restricted lateral mobility. This study identifies novel mechanisms of negative regulation of a type-II TGFβ-SF receptor through cleavage, intracellular retention and/or promiscuous disulfide-bond mediated homo-oligomerization.

TGF-β signaling to chromatin: how Smads regulate transcription during self-renewal and differentiation

Ligands of the TGF-β superfamily (including the TGF-βs, Nodal and BMPs) play instructive roles during embryonic development. This is achieved by regulation of genes important for both maintaining pluripotency and germ layer specification and differentiation. Here we review how the TGF-β superfamily ligands signal to the chromatin to regulate transcription during development. The effectors of the pathway, the Smad transcription factors, are regulated in a combinatorial and spatiotemporal manner. This occurs via post-translational modifications affecting stability, localization and activity, as well as through interactions with other transcription factors and chromatin modifying enzymes, which occur on DNA. Expression profiling and Chromatin Immunoprecipitation have defined Smad target genes and binding sites on a genome-wide scale, which vary between cell types and differentiation stages. This has led to the insight that Smad-mediated transcriptional responses are influenced by the presence of master transcription factors, such as OCT4, SOX2 and NANOG in embryonic stem cells, interaction with other signal-induced factors, as well as by the general chromatin remodeling machinery. Interplay with transcriptional repressors and the polycomb group proteins also regulates the balance between expression of self-renewal and mesendoderm-specific genes in embryonic stem cells and during early development.

microRNA and non-canonical TGF-β signalling: implications for prostate cancer therapy

The incidence of prostate cancer is increasing worldwide and marks a significant health issue. Paired with this, current therapeutic options for advanced prostate cancer, notably androgen deprivation therapy (ADT), fail to provide a consistent level of efficacy throughout the treatment period, highlighting the need for new robust therapies. Growth factors, such as Transforming Growth Factor-beta (TGF-β), possess the ability to impede cancer development in the early stages, via alterations in either apoptosis, cell proliferation, or the promotion of cellular senescence. However, later in the pathogenesis, advanced prostate cancer cells become insensitive to the previously beneficial effects of TGF-β. The molecular mechanisms behind this acquired insensitivity are not well understood. Thus, the aim of this review is to examine the effects of a class of small non-coding RNA, microRNA (miRNA), on TGF-β signalling. The impact of miRNA on the canonical TGF-β Smad signalling pathway has been well investigated, hence, in this review, we will examine whether miRNA targeting members of non-canonical TGF-β signalling members, such as, Erk, RhoA, PI3K/Akt and JNK/p38 could provide alternate therapeutic options for advanced prostate cancer.

Setdb2 controls convergence and extension movements during zebrafish gastrulation by transcriptional regulation of dvr1

As the primary driving forces of gastrulation, convergence and extension (C&E) movements lead to a medio-lateral narrowing and an anterior-posterior elongation of the embryonic body axis. Histone methylation as a post-translational modification plays a critical role in early embryonic development, but its functions in C&E movements remain largely unknown. Here, we show that the setdb2-dvr1 transcriptional cascade plays a critical role in C&E movements during zebrafish gastrulation. Knockdown of Setdb2, a SET domain-containing protein possessing a potential histone H3K9 methyltransferase activity, induced abnormal C&E movements, resulting in anterior-posterior shortening and medio-lateral expansion of the embryonic axis, as well as abnormal notochord cell polarity. Furthermore, we found that Setdb2 functions through fine-tuning the expression of dvr1, a ligand of the TGF-β superfamily, to an appropriate level to ensure proper C&E movements in a non-cell-autonomous manner. In addition, both overexpression and knockdown of Dvr1 at the one-cell stage resulted in defects at epiboly and C&E. These data demonstrate that Setdb2 is a novel regulator for C&E movements and acts by modulating the expression level of dvr1, suggesting that Dvr1 acts as a direct and essential mediator for C&E cell movements.