The secreted AdamTS-A metalloprotease is required for collective cell migration

The journey of a generation: advances and promises in the study of primordial germ cell migration

The germline provides the genetic and non-genetic information that passes from one generation to the next. Given this important role in species propagation, egg and sperm precursors, called primordial germ cells (PGCs), are one of the first cell types specified during embryogenesis. In fact, PGCs form well before the bipotential somatic gonad is specified. This common feature of germline development necessitates that PGCs migrate through many tissues to reach the somatic gonad. During their journey, PGCs must respond to select environmental cues while ignoring others in a dynamically developing embryo. The complex multi-tissue, combinatorial nature of PGC migration is an excellent model for understanding how cells navigate complex environments in vivo. Here, we discuss recent findings on the migratory path, the somatic cells that shepherd PGCs, the guidance cues somatic cells provide, and the PGC response to these cues to reach the gonad and establish the germline pool for future generations. We end by discussing the fate of wayward PGCs that fail to reach the gonad in diverse species. Collectively, this field is poised to yield important insights into emerging reproductive technologies.

Coordination of cell cycle and morphogenesis during organ formation

Organ formation requires precise regulation of cell cycle and morphogenetic events. Using the Drosophila embryonic salivary gland (SG) as a model, we uncover the role of the SP1/KLF transcription factor Huckebein (Hkb) in coordinating cell cycle regulation and morphogenesis. The hkb mutant SG exhibits defects in invagination positioning and organ size due to the abnormal death of SG cells. Normal SG development involves distal-to-proximal progression of endoreplication (endocycle), whereas hkb mutant SG cells undergo abnormal cell division, leading to cell death. Hkb represses the expression of key cell cycle and pro-apoptotic genes in the SG. Knockdown of cyclin E or cyclin-dependent kinase 1, or overexpression of fizzy-related rescues most of the morphogenetic defects observed in the hkb mutant SG. These results indicate that Hkb plays a critical role in controlling endoreplication by regulating the transcription of key cell cycle effectors to ensure proper organ formation.

The RNF220 domain nuclear factor Teyrha-Meyrha (Tey) regulates the migration and differentiation of specific visceral and somatic muscles in Drosophila

Development of the visceral musculature of the Drosophila midgut encompasses a closely coordinated sequence of migration events of cells from the trunk and caudal visceral mesoderm that underlies the formation of the stereotypic orthogonal pattern of circular and longitudinal midgut muscles. Our study focuses on the last step of migration and morphogenesis of longitudinal visceral muscle precursors and shows that these multinucleated precursors utilize dynamic filopodial extensions to migrate in dorsal and ventral directions over the forming midgut tube. The establishment of maximal dorsoventral distances from one another, and anteroposterior alignments, lead to the equidistant coverage of the midgut with longitudinal muscle fibers. We identify Teyrha-Meyhra (Tey), a tissue-specific nuclear factor related to the RNF220 domain protein family, as a crucial regulator of this process of muscle migration and morphogenesis that is further required for proper differentiation of longitudinal visceral muscles. In addition, Tey is expressed in a single somatic muscle founder cell in each hemisegment, regulates the migration of this founder cell, and is required for proper pathfinding of its developing myotube to specific myotendinous attachment sites.

Degradomic Identification of Membrane Type 1-Matrix Metalloproteinase as an ADAMTS9 and ADAMTS20 Substrate

The secreted metalloproteases ADAMTS9 and ADAMTS20 are implicated in extracellular matrix proteolysis and primary cilium biogenesis. Here, we show that clonal gene-edited RPE-1 cells in which ADAMTS9 was inactivated, and which constitutively lack ADAMTS20 expression, have morphologic characteristics distinct from parental RPE-1 cells. To investigate underlying proteolytic mechanisms, a quantitative terminomics method, terminal amine isotopic labeling of substrates was used to compare the parental and gene-edited RPE-1 cells and their medium to identify ADAMTS9 substrates. Among differentially abundant neo-amino (N) terminal peptides arising from secreted and transmembrane proteins, a peptide with lower abundance in the medium of gene-edited cells suggested cleavage at the Tyr314-Gly315 bond in the ectodomain of the transmembrane metalloprotease membrane type 1-matrix metalloproteinase (MT1-MMP), whose mRNA was also reduced in gene-edited cells. This cleavage, occurring in the MT1-MMP hinge, that is, between the catalytic and hemopexin domains, was orthogonally validated both by lack of an MT1-MMP catalytic domain fragment in the medium of gene-edited cells and restoration of its release from the cell surface by reexpression of ADAMTS9 and ADAMTS20 and was dependent on hinge O-glycosylation. A C-terminally semitryptic MT1-MMP peptide with greater abundance in WT RPE-1 medium identified a second ADAMTS9 cleavage site in the MT1-MMP hemopexin domain. Consistent with greater retention of MT1-MMP on the surface of gene-edited cells, pro-MMP2 activation, which requires cell surface MT1-MMP, was increased. MT1-MMP knockdown in gene-edited ADAMTS9/20-deficient cells restored focal adhesions but not ciliogenesis. The findings expand the web of interacting proteases at the cell surface, suggest a role for ADAMTS9 and ADAMTS20 in regulating cell surface activity of MT1-MMP, and indicate that MT1-MMP shedding does not underlie their observed requirement in ciliogenesis.

The Role of the miR-548au-3p/CA12 Axis in Tracheal Chondrogenesis in Congenital Pulmonary Airway Malformations

Background

Literature has identified differentially expressed miRNAs in congenital pulmonary airway malformation (CPAM). However, the functional role of these miRNAs in CPAM remains unclear.

Methods

We obtained diseased lung tissues as well as adjacent normal lung tissue from CPAM patients attending the centre. Hematoxylin and eosin (H&E) and Alcian blue staining were performed. Differentially expressed mRNA expression profile was CPAM tissue, and matched normal tissue specimens were examined by high-throughput RNA sequencing. CCK-8 assay, EdU staining, TUNEL staining, flow cytometry, and the Transwell assay were performed to investigate the effect of miR-548au-3p/CA12 axis on proliferation, apoptosis, and chondrogenic differentiation in rat tracheal chondrocytes. mRNA and protein expression levels were determined using reverse transcription-quantitative PCR and western blot analysis, respectively. The relationship between miR-548au-3p and CA12 was evaluated using the luciferase reporter assay.

Results

The expression level of miR-548au-3p was significantly increased in diseased tissues compared with normal adjacent tissues from patients with CPAM. Our results indicate that miR-548au-3p functions as a positive regulator in rat tracheal chondrocyte proliferation and chondrogenic differentiation. At molecular level, miR-548au-3p promoted N-cadherin, MMP13, and ADAMTS4 expressions and reduced E-cadherin, aggrecan, and Col2A1 expressions. CA12 has been previously reported as a predicted target of miR-548au-3p, and here, we show that overexpression of CA12 in rat tracheal chondrocyte mimics the effects of inhibition of miR-548au-3p. On the other hand, CA12 knockdown reversed the effects of miR-548au-3p on cell proliferation, apoptosis, and chondrogenic differentiation.

Conclusions

In conclusion, the miR-548au-3p/CA12 axis plays a role in the pathogenesis of CPAM and may lead to identification of new approaches for CPAM treatment.

Metzincin metalloproteases in PGC migration and gonadal sex conversion

Development of a functional gonad includes migration of primordial germ cells (PGCs), differentiations of somatic and germ cells, formation of primary follicles or spermatogenic cysts with somatic gonadal cells, development and maturation of gametes, and subsequent releasing of mature germ cells. These processes require extensive cellular and tissue remodeling, as well as broad alterations of the surrounding extracellular matrix (ECM). Metalloproteases, including MMPs (matrix metalloproteases), ADAMs (a disintegrin and metalloproteinases), and ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs), are suggested to have critical roles in the remodeling of the ECM during gonad development. However, few research articles and reviews are available on the functions and mechanisms of metalloproteases in remodeling gonadal ECM, gonadal development, or gonadal differentiation. Moreover, most studies focused on the roles of transcription and growth factors in early gonad development and primary sex determination, leaving a significant knowledge gap on how differentially expressed metalloproteases exert effects on the ECM, cell migration, development, and survival of germ cells during the development and differentiation of ovaries or testes. We will review gonad development with focus on the evidence of metalloprotease involvements, and with an emphasis on zebrafish as a model for studying gonadal sex differentiation and metalloprotease functions.

Identification of the extracellular metallo-endopeptidases ADAM and ADAMTS in the yellow fever mosquito Aedes aegypti

The mosquito Aedes aegypti is a major vector for dengue, Zika, yellow fever, and chikungunya (CHIKV) viruses, which cause significant morbidity and mortality among human populations in the tropical regions of the world. Following ingestion of a viremic bloodmeal from a vertebrate host, an arbovirus needs to productively infect the midgut epithelium of the mosquito. De novo synthesized virions then exit the midgut by traversing the surrounding basal lamina (BL) in order to disseminate to secondary tissues and infect those. Once the salivary glands are infected, the virus is transmitted to a vertebrate host along with saliva released during probing of the mosquito. Midgut tissue distention due to bloodmeal ingestion leads to remodeling of the midgut structure and facilitates virus dissemination from the organ. Previously, we described the matrix-metalloproteinases (MMP) of Ae. aegypti as zinc ion dependent endopeptidases (Metzincins) and showed MMP activity during midgut BL rearrangement as a consequence of bloodmeal ingestion and subsequent digestion thereby affecting arbovirus dissemination from the midgut. Here we investigate the ADAM/ADAMTS of Ae. aegypti, which form another major group of multi-domain proteinases within the Metzincin superfamily and are active during extra-cellular matrix (ECM) remodeling. Seven different ADAM and five ADAMTS were identified in Ae. aegypti. The functional protein domain structures of the identified mosquito ADAM resembled those of human ADAM10, ADAM12, and ADAM17, while two of the five mosquito ADAMTS had human orthologs. Expression profiling of Ae. aegypti ADAM/ADAMTS in immature forms, whole body-females, midguts, and ovarian tissues showed transcriptional activity of the proteinases during metamorphosis, bloodmeal ingestion/digestion, and female reproduction. Custom-made antibodies to ADAM10a and ADAM12c showed that both were strongly expressed in midgut and ovarian tissues. Furthermore, transient silencing of ADAM12c significantly reduced the carcass infection rate with CHIKV at 24 h post-infection, while silencing of ADAM12a significantly increased viral titers in secondary tissues at the same time point. Our results indicate a functional specificity for several ADAM/ADAMTS in those selected mosquito tissues.

The Mechanism and Role of ADAMTS Protein Family in Osteoarthritis

Osteoarthritis (OA) is a principal cause of aches and disability worldwide. It is characterized by the inflammation of the bone leading to degeneration and loss of cartilage function. Factors, including diet, age, and obesity, impact and/or lead to osteoarthritis. In the past few years, OA has received considerable scholarly attention owing to its increasing prevalence, resulting in a cumbersome burden. At present, most of the interventions only relieve short-term symptoms, and some treatments and drugs can aggravate the disease in the long run. There is a pressing need to address the safety problems due to osteoarthritis. A disintegrin-like and metalloprotease domain with thrombospondin type 1 repeats (ADAMTS) metalloproteinase is a kind of secretory zinc endopeptidase, comprising 19 kinds of zinc endopeptidases. ADAMTS has been implicated in several human diseases, including OA. For example, aggrecanases, ADAMTS-4 and ADAMTS-5, participate in the cleavage of aggrecan in the extracellular matrix (ECM); ADAMTS-7 and ADAMTS-12 participate in the fission of Cartilage Oligomeric Matrix Protein (COMP) into COMP lyase, and ADAMTS-2, ADAMTS-3, and ADAMTS-14 promote the formation of collagen fibers. In this article, we principally review the role of ADAMTS metalloproteinases in osteoarthritis. From three different dimensions, we explain how ADAMTS participates in all the following aspects of osteoarthritis: ECM, cartilage degeneration, and synovial inflammation. Thus, ADAMTS may be a potential therapeutic target in osteoarthritis, and this article may render a theoretical basis for the study of new therapeutic methods for osteoarthritis.

Nucleoporin107 mediates female sexual differentiation via Dsx

We recently identified a missense mutation in Nucleoporin107 (Nup107; D447N) underlying XX-ovarian-dysgenesis, a rare disorder characterized by underdeveloped and dysfunctional ovaries. Modeling of the human mutation in Drosophila or specific knockdown of Nup107 in the gonadal soma resulted in ovarian-dysgenesis-like phenotypes. Transcriptomic analysis identified the somatic sex-determination gene doublesex (dsx) as a target of Nup107. Establishing Dsx as a primary relevant target of Nup107, either loss or gain of Dsx in the gonadal soma is sufficient to mimic or rescue the phenotypes induced by Nup107 loss. Importantly, the aberrant phenotypes induced by compromising either Nup107 or dsx are reminiscent of BMP signaling hyperactivation. Remarkably, in this context, the metalloprotease AdamTS-A, a transcriptional target of both Dsx and Nup107, is necessary for the calibration of BMP signaling. As modulation of BMP signaling is a conserved critical determinant of soma-germline interaction, the sex and tissue specific deployment of Dsx-F by Nup107 seems crucial for the maintenance of the homeostatic balance between the germ cells and somatic gonadal cells.

Simulation and in vivo experimentation predict AdamTS-A location of function during caudal visceral mesoderm (CVM) migration in Drosophila

BACKGROUND

Caudal visceral mesoderm (CVM) cells migrate as a loose collective along the trunk visceral mesoderm (TVM) and are surrounded by extracellular matrix (ECM). In this study, we examined how one extracellular protease, AdamTS-A, facilitates CVM migration.

RESULTS

A comparison of mathematical simulation to experimental results suggests that location of AdamTS-A action in CVM cells is on the sides of the cell not in contact with the TVM, predominantly at the CVM-ECM interface. CVM migration from a top-down view showed CVM cells migrating along the outside of the TVM substrate in the absence of AdamTS-A. Moreover, over-expression of AdamTS-A resulted in similar, but milder, mis-migration of the CVM. These results contrast with the salivary gland where AdamTS-A is proposed to cleave connections at the trailing edge of migrating cells. Subcellular localization of GFP-tagged AdamTS-A suggests this protease is not limited to functioning at the trailing edge of CVM cells.

CONCLUSION

Using both in vivo experimentation and mathematical simulations, we demonstrated that AdamTS-A cleaves connections between CVM cells and the ECM on all sides not attached to the TVM. Clearly, AdamTS-A has a more expansive role around the entire cell in cleaving cell-ECM attachments in cells migrating as a loose collective. This article is protected by copyright. All rights reserved.

Metalloproteases in gonad formation and ovulation

Changes in expression or activation of various metalloproteases including matrix metalloproteases (Mmp), a disintegrin and metalloprotease (Adam) and a disintegrin and metalloprotease with thrombospondin motif (Adamts), and their endogenous inhibitors (tissue inhibitors of metalloproteases, Timp), have been shown to be critical for ovulation in various species from studies in past decades. Some of these metalloproteases such as Adamts1, Adamts9, Mmp2, and Mmp9 have also been shown to be regulated by luteinizing hormone (LH) and/or progestin, which are essential triggers for ovulation in all vertebrate species. Most of these metalloproteases also express broadly in various tissues and cells including germ cells and somatic gonad cells. Thus, metalloproteases likely play roles in gonad formation processes comprising primordial germ cell (PGC) migration, development of germ and somatic cells, and sex determination. However, our knowledge on the functions and mechanisms of metalloproteases in these processes in vertebrates is still lacking. This review will summarize our current knowledge on the metalloproteases in ovulation and gonad formation with emphasis on PGC migration and germ cell development.

Crosstalk between basal extracellular matrix adhesion and building of apical architecture during morphogenesis

Tissues build complex structures like lumens and microvilli to carry out their functions. Most of the mechanisms used to build these structures rely on cells remodelling their apical plasma membranes, which ultimately constitute the specialised compartments. In addition to apical remodelling, these shape changes also depend on the proper attachment of the basal plasma membrane to the extracellular matrix (ECM). The ECM provides cues to establish apicobasal polarity, and it also transduces forces that allow apical remodelling. However, physical crosstalk mechanisms between basal ECM attachment and the apical plasma membrane remain understudied, and the ones described so far are very diverse, which highlights the importance of identifying the general principles. Here, we review apicobasal crosstalk of two well-established models of membrane remodelling taking place during Drosophila melanogaster embryogenesis: amnioserosa cell shape oscillations during dorsal closure and subcellular tube formation in tracheal cells. We discuss how anchoring to the basal ECM affects apical architecture and the mechanisms that mediate these interactions. We analyse this knowledge under the scope of other morphogenetic processes and discuss what aspects of apicobasal crosstalk may represent widespread phenomena and which ones are used to build subsets of specialised compartments.

A kaleidoscopic view of ovarian genes associated with premature ovarian insufficiency and senescence

Ovarian infertility and subfertility presenting with premature ovarian insufficiency (POI) and diminished ovarian reserve are major issues facing the developed world due to the trend of delaying childbirth. Ovarian senescence and POI represent a continuum of physiological/pathophysiological changes in ovarian follicle functions. Based on advances in whole exome sequencing, evaluation of gene copy variants, together with family-based and genome-wide association studies, we discussed genes responsible for POI and ovarian senescence. We used a gene-centric approach to sort out literature deposited in the Ovarian Kaleidoscope database (http://okdb.appliedbioinfo.net) by sub-categorizing candidate genes as ligand-receptor signaling, meiosis and DNA repair, transcriptional factors, RNA metabolism, enzymes, and others. We discussed individual gene mutations found in POI patients and verification of gene functions in gene-deleted model organisms. Decreased expression of some of the POI genes could be responsible for ovarian senescence, especially those essential for DNA repair, meiosis and mitochondrial functions. We propose to set up a candidate gene panel for targeted sequencing in POI patients together with studies on mitochondria-associated genes in middle-aged subfertile patients.

Delay in primordial germ cell migration in adamts9 knockout zebrafish

Adamts9 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 9) is one of a few metalloproteinases structurally conserved from C. elegans to humans and is indispensable in germ cell migration in invertebrates. However, adamts9's roles in germ cell migration in vertebrates has not been examined. In the present study, we found zygotic expression of adamts9 started around the germ ring stage and reached peak levels at 3 days post fertilization (dpf) in zebrafish. The migration of primordial germ cells (PGC) was completed within 24 hours (h) in wildtype siblings, while a delay in PGC migration was found at 15 and 24-h post-fertilization (hpf) in the Adamts9 knockout (KO). However, the delayed PGC migration in Adamts9 KO disappeared at 48 hpf. Our study suggests a conserved function of Adamts9 in germ cell migration among invertebrates and vertebrates. In addition, our results also suggest that Adamts9 is not essential for germ cell migration as reported in C. elegans, possibly due to expansion of Adamts family members and compensatory roles from other metalloproteinases in vertebrates. Further studies are required in order to elucidate the functions and mechanisms of metalloproteinases in germ cell migration and gonad formation in vertebrates.

ADAMTS proteases in cardiovascular physiology and disease

The a disintegrin-like and metalloproteinase with thrombospondin motif (ADAMTS) family comprises 19 proteases that regulate the structure and function of extracellular proteins in the extracellular matrix and blood. The best characterized cardiovascular role is that of ADAMTS-13 in blood. Moderately low ADAMTS-13 levels increase the risk of ischeamic stroke and very low levels (less than 10%) can cause thrombotic thrombocytopenic purpura (TTP). Recombinant ADAMTS-13 is currently in clinical trials for treatment of TTP. Recently, new cardiovascular roles for ADAMTS proteases have been discovered. Several ADAMTS family members are important in the development of blood vessels and the heart, especially the valves. A number of studies have also investigated the potential role of ADAMTS-1, -4 and -5 in cardiovascular disease. They cleave proteoglycans such as versican, which represent major structural components of the arteries. ADAMTS-7 and -8 are attracting considerable interest owing to their implication in atherosclerosis and pulmonary arterial hypertension, respectively. Mutations in the ADAMTS19 gene cause progressive heart valve disease and missense variants in ADAMTS6 are associated with cardiac conduction. In this review, we discuss in detail the evidence for these and other cardiovascular roles of ADAMTS family members, their proteolytic substrates and the potential molecular mechanisms involved.

Association of Polymorphism rs67920064 in ADAMTS9 Gene with Mandibular Retrognathism in a Chinese Population

BACKGROUND Mandibular retrognathism is a common oral and maxillofacial deformity that may cause a series of physical and psychological diseases. Many studies indicated that genetic factors play an important role in the occurrence of mandibular retrognathism. In this study, we assess the association between polymorphism rs67920064 in ADAMTS9 gene and mandibular retrognathism in a Chinese population. MATERIAL AND METHODS Sixty participants (20 to 45 y, mean age 32.79 y) were classified into Class I or mandibular retrognathism skeletal-facial profile groups in accordance with cephalometric parameters. Thirty patients with mandibular retrognathism were assigned to the subject group; the others were assigned to the control group. Cephalometric parameters including sella-nasion A point, SN point B, condylion-gnathion (Gn), and gonion-Gn were recorded. Saliva samples from these participants were collected and polymerase chain reaction-restriction fragment length polymorphism was used to distinguish different genotypes of the rs67920064 single nucleotide polymorphisms (SNPs).We evaluated the correlation between mandibular retrognathism and polymorphism rs67920064 in the ADAMTS9 gene. RESULTS The distribution of rs67920064 gene polymorphism in ADAMST9 gene conforms to Hardy-Weinberg equilibrium. The A point-nasion-B point angle of the participants with the GA genotype of the rs67920064 SNP showed significantly decreased values (P<0.05), but there was no difference in length of mandibular body. Beyond that, the chi-square test showed that the GA genotype of rs67920064 SNP was highly associated with mandibular retrognathism (P<0.05). CONCLUSIONS Our research shows that there is an association between polymorphism rs67920064 in the ADAMTS9 gene and mandibular retrognathism in the Chinese population. Individuals with the GA phenotype are more likely to have mandibular retrognathism.

Collective Migrations of Drosophila Embryonic Trunk and Caudal Mesoderm-Derived Muscle Precursor Cells

Mesoderm migration in the Drosophila embryo is a highly conserved, complex process that is required for the formation of specialized tissues and organs, including the somatic and visceral musculature. In this FlyBook chapter, we will compare and contrast the specification and migration of cells originating from the trunk and caudal mesoderm. Both cell types engage in collective migrations that enable cells to achieve new positions within developing embryos and form distinct tissues. To start, we will discuss specification and early morphogenetic movements of the presumptive mesoderm, then focus on the coordinate movements of the two subtypes trunk mesoderm and caudal visceral mesoderm, ending with a comparison of these processes including general insights gained through study.

Zebrafish as a model for studying ovarian development: Recent advances from targeted gene knockout studies

Ovarian development is a complex process controlled by precise coordination of multiple factors. The targeted gene knockout technique is a powerful tool to study the functions of these factors. The successful application of this technique in mice in the past three decades has significantly enhanced our understanding on the molecular mechanism of ovarian development. Recently, with the advent of genome editing techniques, targeted gene knockout research can be carried out in many species. Zebrafish has emerged as an excellent model system to study the control of ovarian development. Dozens of genes related to ovarian development have been knocked out in zebrafish in recent years. Much new information and perspectives on the molecular mechanism of ovarian development have been obtained from these mutant zebrafish. Some findings have challenged conventional views. Several genes have been identified for the first time in vertebrates to control ovarian development. Focusing on ovarian development, the purpose of this review is to briefly summarize recent findings using these gene knockout zebrafish models, and compare these findings with mammalian models. These established mutants and rapid development of gene knockout techniques have prompted zebrafish as an ideal animal model for studying ovarian development.

Extracellular matrix dynamics in tubulogenesis

Biological tubes form in a variety of shapes and sizes. Tubular topology of cells and tissues is a widely recognizable histological feature of multicellular life. Fluid secretion, storage, transport, absorption, exchange, and elimination-processes central to metazoans-hinge on the exquisite tubular architectures of cells, tissues, and organs. In general, the apparent structural and functional complexity of tubular tissues and organs parallels the architectural and biophysical properties of their constitution, i.e., cells and the extracellular matrix (ECM). Together, cellular and ECM dynamics determine the developmental trajectory, topological characteristics, and functional efficacy of biological tubes. In this review of tubulogenesis, we highlight the multifarious roles of ECM dynamics-the less recognized and poorly understood morphogenetic counterpart of cellular dynamics. The ECM is a dynamic, tripartite composite spanning the luminal, abluminal, and interstitial space within the tubulogenic realm. The critical role of ECM dynamics in the determination of shape, size, and function of tubes is evinced by developmental studies across multiple levels-from morphological through molecular-in model tubular organs.

Upregulation of adamts9 by gonadotropin in preovulatory follicles of zebrafish

Previously we had identified adamts9 as a downstream target of Pgr, which is essential for ovulation in zebrafish. The primary goal of this study is to determine whether human chorionic gonadotropin (hCG, LH analog) also regulate adamts9 expression prior to ovulation. The expression of adamts9 was induced by hCG in a dose and time dependent manner in zebrafish preovulatory follicles in vitro. Interestingly, the stimulatory effect of hCG on adamts9 expression was not blocked in pgr^-/- follicles but blocked in lhcgr^-/-. This effect of hCG was via Lhcgr and its associated cAMP and PKC signaling pathways. Reduced fecundity and reduced expression of adamts9 were also found in lhcgr^-/- females in vivo. Therefore, we have provided the first evidence of gonadotropin (hCG) regulated adamts9 in zebrafish, which could be important for ovulation.

Versican is crucial for the initiation of cardiovascular lumen development in medaka (Oryzias latipes)

Versican is an evolutionary conserved extracellular matrix proteoglycan, and versican expression loss in mice results in embryonic lethality owing to cardiovascular defects. However, the in utero development of mammals limits our understanding of the precise role of versican during cardiovascular development. Therefore, the use of evolutionarily distant species that develop ex utero is more suitable for studying the mechanistic basis of versican activity. We performed ENU mutagenesis screening to identify medaka mutants with defects in embryonic cardiovascular development. In this study, we described a recessive point mutation in the versican 3'UTR resulting in reduced versican protein expression. The fully penetrant homozygous mutant showed termination of cardiac development at the linear heart tube stage and exhibited absence of cardiac looping, a constricted outflow tract, and no cardiac jelly. Additionally, progenitor cells did not migrate from the secondary source towards the arterial pole of the linear heart tube, resulting in a constricted outflow tract. Furthermore, mutants lacked blood flow and vascular lumen despite continuous peristaltic heartbeats. These results enhance our understanding of the mechanistic basis of versican in cardiac development, and this mutant represents a novel genetic model to investigate the mechanisms of vascular tubulogenesis.

Role of tbc1 in Drosophila embryonic salivary glands

BACKGROUND

CG4552/tbc1 was identified as a downstream target of Fork head (Fkh), the single Drosophila member of the FoxA family of transcription factors and a major player in salivary gland formation and homeostasis. Tbc1 and its orthologues have been implicated in phagocytosis, the innate immune response, border cell migration, cancer and an autosomal recessive form of non-degenerative Pontocerebellar hypoplasia. Recently, the mammalian Tbc1 orthologue, Tbc1d23, has been shown to bind both the conserved N-terminal domains of two Golgins (Golgin-97 and Golgin-245) and the WASH complex on endosome vesicles. Through this activity, Tbc1d23 has been proposed to link endosomally-derived vesicles to their appropriate target membrane in the trans Golgi (TGN).

RESULTS

In this paper, we provide an initial characterization of Drosophila orthologue, we call tbc1. We show that, like its mammalian orthologue, Tbc1 localizes to the trans Golgi. We show that it also colocalizes with a subset of Rabs associated with both early and recycling endosomes. Animals completely missing tbc1 survive, but females have fertility defects. Consistent with the human disease, loss of tbc1 reduces optic lobe size and increases response time to mechanical perturbation. Loss and overexpression of tbc1 in the embryonic salivary glands leads to secretion defects and apical membrane irregularities.

CONCLUSIONS

These findings support a role for tbc1 in endocytic/membrane trafficking, consistent with its activities in other systems.

A disintegrin-like and metalloproteinase domain with thrombospondin type 1 motif 9 (ADAMTS9) regulates fibronectin fibrillogenesis and turnover

The secreted metalloprotease ADAMTS9 has dual roles in extracellular matrix (ECM) turnover and biogenesis of the primary cilium during mouse embryogenesis. Its gene locus is associated with several human traits and disorders, but ADAMTS9 has few known interacting partners or confirmed substrates. Here, using a yeast two-hybrid screen for proteins interacting with its C-terminal Gon1 domain, we identified three putative ADAMTS9-binding regions in the ECM glycoprotein fibronectin. Using solid-phase binding assays and surface plasmon resonance experiments with purified proteins, we demonstrate that ADAMTS9 and fibronectin interact. ADAMTS9 constructs, including those lacking Gon1, co-localized with fibronectin fibrils formed by cultured fibroblasts lacking fibrillin-1, which co-localizes with fibronectin and binds several ADAMTSs. We observed no fibrillar ADAMTS9 staining after blockade of fibroblast fibronectin fibrillogenesis with a peptide based on the functional upstream domain of a Staphylococcus aureus adhesin. These findings indicate that ADAMTS9 binds fibronectin dimers and fibrils directly through multiple sites in both molecules. Proteolytically active ADAMTS9, but not a catalytically inactive variant, disrupted fibronectin fibril networks formed by fibroblasts in vitro, and ADAMTS9-deficient RPE1 cells assembled a robust fibronectin fibril network, unlike WT cells. Targeted LC-MS analysis of fibronectin digested by ADAMTS9-expressing cells identified a semitryptic peptide arising from cleavage at Gly2196-Leu2197 We noted that this scissile bond is in the linker between fibronectin modules III17 and I10, a region targeted also by other proteases. These findings, along with stronger fibronectin staining previously observed in Adamts9 mutant embryos, suggest that ADAMTS9 contributes to fibronectin turnover during ECM remodeling.

Adamts9 is necessary for ovarian development in zebrafish

Expression of adamts9 (A disintegrin and metalloprotease with thrombospondin type-1 motif, member 9) increases dramatically in the somatic cells surrounding oocytes during ovulation in vertebrates from zebrafish to human. However, the function of Adamts9 during ovulation has not been determined due to the embryonic lethality of knockouts in mice and Drosophila. To identify the role of Adamts9 during ovulation we generated knockout (adamts9^-/-) zebrafish using CRISPR/Cas9 and characterized the effects of the mutation. From 1047 fish generated by crossing adamts9^+/- pairs, we found significantly fewer adult adamts9^-/- fish (4%) than predicted by Mendelian ratios (25%). Of the mutants found, there was a significant male bias (82%). Only 3 female mutants were identified (7%), and they had small ovaries with few stage III and IV oocytes compared to wildtype (wt) counterparts of comparable size and age. Astoundingly, the remaining mutants (11%) did not appear to have normal testis or ovaries. Instead there was a pair of transparent, ovarian-like membranous shells that filled the abdominal cavity. Histological examination confirmed that shells were largely empty with no internal structure. Surprisingly, seminiferous tubules and various spermatocytes including mature spermatozoa were observed on the periphery of these transparent shells. No female or female like knockouts were observed to release eggs, and no ovulated oocytes were observed in histological sections. To our knowledge, this is the first report of an adamts9 global knockout model in any adult vertebrates and the first description of how gonadal sex and structure are affected- highlighting the importance of Adamts9 during gonadal development and the value of zebrafish as a model organism.

The Role of Tissue Inhibitors of Metalloproteinases in Organ Development and Regulation of ADAMTS Family Metalloproteinases in Caenorhabditis elegans

Remodeling of the extracellular matrix supports tissue and organ development, by regulating cellular morphology and tissue integrity. However, proper extracellular matrix remodeling requires spatiotemporal regulation of extracellular metalloproteinase activity. Members of the ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family, including MIG-17 and GON-1, are evolutionarily conserved, secreted, zinc-requiring metalloproteinases. Although these proteases are required for extracellular matrix remodeling during gonadogenesis in Caenorhabditis elegans, their in vivo regulatory mechanisms remain to be delineated. Therefore, we focused on the C. elegans tissue inhibitors of metalloproteinases (TIMPs), TIMP-1 and CRI-2 Analysis of the transcription and translation products for GFP/Venus fusions, with TIMP-1 or CRI-2, indicated that these inhibitors were secreted and localized to the basement membrane of gonads and the plasma membrane of germ cells. A timp-1 deletion mutant exhibited gonadal growth defects and sterility, and the phenotypes of this mutant were fully rescued by a TIMP-1::Venus construct, but not by a TIMP-1(C21S)::Venus mutant construct, in which the inhibitor coding sequence had been mutated. Moreover, genetic data suggested that TIMP-1 negatively regulates proteolysis of the α1 chain of type IV collagen. We also found that the loss-of-function observed for the mutants timp-1 and cri-2 involves a partial suppression of gonadal defects found for the mutants mig-17/ADAMTS and gon-1/ADAMTS, and that this suppression was canceled upon overexpression of gon-1 or mig-17, respectively. Based on these results, we propose that both TIMP-1 and CRI-2 act as inhibitors of MIG-17 and GON-1 ADAMTSs to regulate gonad development in a noncell-autonomous manner.

An ADAMTS Sol narae is required for cell survival in Drosophila

Cell survival is essential for all living organisms to cope against multiple environmental insults. Intercellular signaling between dying and surviving cells plays an important role to ensure compensatory proliferation, preventing tissue loss after environmental stresses. Here, we show that Sol narae (Sona), a Disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) in Drosophila is required for cell survival. sona exhibited a positive genetic interaction with Death-associated inhibitor of apoptosis 1 (Diap1), and a negative genetic interaction with reaper (rpr). Transcription patterns of sona, Diap1, and rpr genes in the pouch region of wing discs were coordinately changed after irradiation. Interestingly, there was a negative correlation in the expression levels of Sona and DIAP1, and both cell types, one with high Sona level and the other with high Diap1 level, were resistant to irradiation-induced cell death. The sona-expressing cells rarely entered into cell cycle themselves but promoted the nearby cells to proliferate in irradiation conditions. We found that these sona-expressing cells are able to upregulate Cyclin D (Cyc D) and increase tissue size. Furthermore, transient Sona overexpression increased survival rate and promoted development of flies in irradiation conditions. We propose that the two types of radiation-resistant cells, one with high Sona level and the other with high Diap1 level, communicate with dying cells and between each other for cell survival and proliferation in response to irradiation.

A Gene Expression Screen in Drosophila melanogaster Identifies Novel JAK/STAT and EGFR Targets During Oogenesis

The Janus Kinase/Signal Transducer and Activator of Transcription (JAK/STAT) and epidermal growth factor receptor (EGFR) signaling pathways are conserved regulators of tissue patterning, morphogenesis, and other cell biological processes. During Drosophila oogenesis, these pathways determine the fates of epithelial follicle cells (FCs). JAK/STAT and EGFR together specify a population of cells called the posterior follicle cells (PFCs), which signal to the oocyte to establish the embryonic axes. In this study, whole genome expression analysis was performed to identify genes activated by JAK/STAT and/or EGFR. We observed that 317 genes were transcriptionally upregulated in egg chambers with ectopic JAK/STAT and EGFR activity in the FCs. The list was enriched for genes encoding extracellular matrix (ECM) components and ECM-associated proteins. We tested 69 candidates for a role in axis establishment using RNAi knockdown in the FCs. We report that the signaling protein Semaphorin 1b becomes enriched in the PFCs in response to JAK/STAT and EGFR. We also identified ADAM metallopeptidase with thrombospondin type 1 motif A (AdamTS-A) as a novel target of JAK/STAT in the FCs that regulates egg chamber shape. AdamTS-A mRNA becomes enriched at the anterior and posterior poles of the egg chamber at stages 6 to 7 and is regulated by JAK/STAT. Altering AdamTS-A expression in the poles or middle of the egg chamber produces rounder egg chambers. We propose that AdamTS-A regulates egg shape by remodeling the basement membrane.

20-Hydroxyecdysone-upregulated proteases involved in Bombyx larval fat body destruction

During insect larval-pupal metamorphosis, the obsolete larval organs and tissues undergo histolysis and programmed cell death to recycle cellular materials. It has been demonstrated that some cathepsins are essential for histolysis in larval tissues, but the process of tissue destruction is not well documented. Fat body, the homologous organ to mammalian liver and adipose tissue, goes through a distinct destruction process during larval-pupal transition. Herein, we found that most of the Bombyx proteases - including Bombyx cathepsin B (BmCatB) (BmCatLL-2), Bombyx cathepsin D (BmCatD), Bombyx cathepsin L like-1 (BmCatLL-1) and -2(BmCatLL-2), Bombyx fibroinase (BmBcp), Bombyx matrix metalloprotease (BmMmp), Bombyx A disintegrin and metalloproteinase with thrombospondin motifs 1 (BmAdamTS-1), Bombyx A disintegrin and metalloproteinase with thrombospondin motifs like (BmAdamTS L) and Bombyx cysteine protease inhibitor (Bmbcpi)- were expressed highly in fat body during feeding and metamorphosis, with a peak occurring during the nonfeeding moulting or prepupal stage, as well as being responsive to 20-hydroxyecdysone (20E). The aforementioned protease genes expression was upregulated by injection of 20E into the feeding larvae, while blocking 20E signalling transduction led to downregulation. Western blotting and immunofluorescent staining of BmCatB and BmBcp confirmed the coincident variation of their messenger RNA (mRNA) and protein level during the development and after the treatments. Moreover, BmCatB, BmBcp, BmMmp and BmAdamTS-1 RNA interference all led to blockage of larval fat body destruction. Taken together, we conclude that 20E regulates larval fat body destruction by upregulating related protease gene expression and protein levels during larval-pupal transition.

The extracellular protease AdamTS-B inhibits vein formation in the Drosophila wing

Vein patterning in the Drosophila wing provides a powerful tool to study regulation of various signaling pathways. Here we show that the ADAMTS extracellular protease AdamTS-B (CG4096) is expressed in the embryonic wing imaginal disc precursor cells and the wing imaginal disc, and functions to inhibit wing vein formation. Knock-down of AdamTS-B displayed posterior crossveins (PCVs) with either extra branches or deltas, or wider PCVs, and a wandering distal tip of the L5 longitudinal vein. Conversely, over-expression of AdamTS-B resulted in a complete absence of the PCV, an incomplete anterior crossvein, and missing distal end of the L5 longitudinal vein. We conclude that AdamTS-B inhibits wing vein formation through negative regulation of signaling pathways, possibly BMP as well as Egfr, displaying the complexity of roles for this family of extracellular proteases.

Development and Function of the Drosophila Tracheal System

The tracheal system of insects is a network of epithelial tubules that functions as a respiratory organ to supply oxygen to various target organs. Target-derived signaling inputs regulate stereotyped modes of cell specification, branching morphogenesis, and collective cell migration in the embryonic stage. In the postembryonic stages, the same set of signaling pathways controls highly plastic regulation of size increase and pattern elaboration during larval stages, and cell proliferation and reprograming during metamorphosis. Tracheal tube morphogenesis is also regulated by physicochemical interaction of the cell and apical extracellular matrix to regulate optimal geometry suitable for air flow. The trachea system senses both the external oxygen level and the metabolic activity of internal organs, and helps organismal adaptation to changes in environmental oxygen level. Cellular and molecular mechanisms underlying the high plasticity of tracheal development and physiology uncovered through research on Drosophila are discussed.

Expression of matrix metalloproteinase genes during basement membrane degradation in the metamorphosis of Bombyx mori

The present study was conducted to clarify the involvement of the basement membrane (BM) in insect metamorphosis through analysis of the expression profile of two types of metalloproteinase (MMP and ADAMTS) genes in several organs, their ecdysone involvement, and the histological change of BM. BM was observed around wing sac and in the wing cavity and around fat bodies at the W0 stage but disappeared after the W3 stage, and wing discs evaginated and fat body cells scattered after the W3 stage. The disappearance of the BM of midgut and silk glands was not observed after the W3 stage, but degenerated epithelium cells in the midgut and shrunken cells in the silk gland were observed after the W3 stage. BmMMP1 showed a peak at P0 in the wing discs, fat bodies, midgut, and silk gland. BmMMP2 showed a broad peak around pupation in the wing discs, fat bodies, midgut, and silk gland. BmADAMTS-1 showed enhanced expression at W2 in the wing discs, fat bodies, midgut, and hemocyte, while BmADAMTS-L showed enhanced expression at W3 in the fat bodies, midgut, silk gland, and hemocyte. After pupation, they showed a different expression in different organs. All of four genes were induced by 20-hydroxyecdysone in wing discs in vitro. The present results suggested the involvement of MMPs and ADAMTS in the BM digestion and the morphogenesis of organs during Bombyx metamorphosis.

The extracellular metalloprotease AdamTS-A anchors neural lineages in place within and preserves the architecture of the central nervous system

The extracellular matrix (ECM) regulates cell migration and sculpts organ shape. AdamTS proteins are extracellular metalloproteases known to modify ECM proteins and promote cell migration, but demonstrated roles for AdamTS proteins in regulating CNS structure and ensuring cell lineages remain fixed in place have not been uncovered. Using forward genetic approaches in Drosophila, we find that reduction of AdamTS-A function induces both the mass exodus of neural lineages out of the CNS and drastic perturbations to CNS structure. Expressed and active in surface glia, AdamTS-A acts in parallel to perlecan and in opposition to viking/collagen IV and βPS-integrin to keep CNS lineages rooted in place and to preserve the structural integrity of the CNS. viking/collagen IV and βPS-integrin are known to promote tissue stiffness and oppose the function of perlecan, which reduces tissue stiffness. Our work supports a model in which AdamTS-A anchors cells in place and preserves CNS architecture by reducing tissue stiffness.

The ADAMTS hyalectanase family: biological insights from diverse species

The a disintegrin-like and metalloproteinase with thrombospondin type-1 motifs (ADAMTS) family of metzincins are complex secreted proteins that have diverse functions during development. The hyalectanases (ADAMTS1, 4, 5, 8, 9, 15 and 20) are a subset of this family that have enzymatic activity against hyalectan proteoglycans, the processing of which has important implications during development. This review explores the evolution, expression and developmental functions of the ADAMTS family, focusing on the ADAMTS hyalectanases and their substrates in diverse species. This review gives an overview of how the family and their substrates evolved from non-vertebrates to mammals, the expression of the hyalectanases and substrates in different species and their functions during development, and how these functions are conserved across species.

Comparative analysis of gene expression profiles for several migrating cell types identifies cell migration regulators

Cell migration is an instrumental process that ensures cells are properly positioned to support the specification of distinct tissue types during development. To provide insight, we used fluorescence activated cell sorting (FACS) to isolate two migrating cell types from the Drosophila embryo: caudal visceral mesoderm (CVM) cells, precursors of longitudinal muscles of the gut, and hemocytes (HCs), the Drosophila equivalent of blood cells. ~350 genes were identified from each of the sorted samples using RNA-seq, and in situ hybridization was used to confirm expression within each cell type or, alternatively, within other interacting, co-sorted cell types. To start, the two gene expression profiling datasets were compared to identify cell migration regulators that are potentially generally-acting. 73 genes were present in both CVM cell and HC gene expression profiles, including the transcription factor zinc finger homeodomain-1 (zfh1). Comparisons with gene expression profiles of Drosophila border cells that migrate during oogenesis had a more limited overlap, with only the genes neyo (neo) and singed (sn) found to be expressed in border cells as well as CVM cells and HCs, respectively. Neo encodes a protein with Zona pellucida domain linked to cell polarity, while sn encodes an actin binding protein. Tissue specific RNAi expression coupled with live in vivo imaging was used to confirm cell-autonomous roles for zfh1 and neo in supporting CVM cell migration, whereas previous studies had demonstrated a role for Sn in supporting HC migration. In addition, comparisons were made to migrating cells from vertebrates. Seven genes were found expressed by chick neural crest cells, CVM cells, and HCs including extracellular matrix (ECM) proteins and proteases. In summary, we show that genes shared in common between CVM cells, HCs, and other migrating cell types can help identify regulators of cell migration. Our analyses show that neo in addition to zfh1 and sn studied previously impact cell migration. This study also suggests that modification of the extracellular milieu may be a fundamental requirement for cells that undergo cell streaming migratory behaviors.

Sol narae (Sona) is a Drosophila ADAMTS involved in Wg signaling

ADAMTS (a disintegrin and metalloproteases with thrombospondin motif) family consists of secreted proteases, and is shown to cleave extracellular matrix proteins. Their malfunctions result in cancers and disorders in connective tissues. We report here that a Drosophila ADAMTS named Sol narae (Sona) promotes Wnt/Wingless (Wg) signaling. sona loss-of-function mutants are lethal and rare escapers had malformed appendages, indicating that sona is essential for fly development and survival. sona exhibited positive genetic interaction with wntless (wls) that encodes a cargo protein for Wg. Loss of sona decreased the level of extracellular Wg, and also reduced the expression level of Wg effector proteins such as Senseless (Sens), Distalless (Dll) and Vestigial (Vg). Sona and Wg colocalized in Golgi and endosomal vesicles, and were in the same protein complex. Furthermore, co-expression of Wg and Sona generated ectopic wing margin bristles. This study suggests that Sona is involved in Wg signaling by regulating the level of extracellular Wg.

Extracellular Mipp1 Activity Confers Migratory Advantage to Epithelial Cells during Collective Migration

Multiple inositol polyphosphate phosphatase (Mipp), a highly conserved but poorly understood histidine phosphatase, dephosphorylates higher-order IPs (IP4-IP6) to IP3. To gain insight into the biological roles of these enzymes, we have characterized Drosophila mipp1. mipp1 is dynamically expressed in the embryonic trachea, specifically in the leading cells of migrating branches at late stages, where Mipp1 localizes to the plasma membrane and filopodia. FGF signaling activates mipp1 expression in these cells, where extensive filopodia form to drive migration and elongation by cell intercalation. We show that Mipp1 facilitates formation and/or stabilization of filopodia in leading cells through its extracellular activity. mipp1 loss decreases filopodia number, whereas mipp1 overexpression increases filopodia number in a phosphatase-activity-dependent manner. Importantly, expression of Mipp1 gives cells a migratory advantage for the lead position in elongating tracheal branches. Altogether, these findings suggest that extracellular pools of inositol polyphosphates affect cell behavior during development.

Ribbon regulates morphogenesis of the Drosophila embryonic salivary gland through transcriptional activation and repression

Transcription factors affect spatiotemporal patterns of gene expression often regulating multiple aspects of tissue morphogenesis, including cell-type specification, cell proliferation, cell death, cell polarity, cell shape, cell arrangement and cell migration. In this work, we describe a distinct role for Ribbon (Rib) in controlling cell shape/volume increases during elongation of the Drosophila salivary gland (SG). Notably, the morphogenetic changes in rib mutants occurred without effects on general SG cell attributes such as specification, proliferation and apoptosis. Moreover, the changes in cell shape/volume in rib mutants occurred without compromising epithelial-specific morphological attributes such as apicobasal polarity and junctional integrity. To identify the genes regulated by Rib, we performed ChIP-seq analysis in embryos driving expression of GFP-tagged Rib specifically in the SGs. To learn if the Rib binding sites identified in the ChIP-seq analysis were linked to changes in gene expression, we performed microarray analysis comparing RNA samples from age-matched wild-type and rib null embryos. From the superposed ChIP-seq and microarray gene expression data, we identified 60 genomic sites bound by Rib likely to regulate SG-specific gene expression. We confirmed several of the identified Rib targets by qRT-pCR and/or in situ hybridization. Our results indicate that Rib regulates cell growth and tissue shape in the Drosophila salivary gland via a diverse array of targets through both transcriptional activation and repression. Furthermore, our results suggest that autoregulation of rib expression may be a key component of the SG morphogenetic gene network.

ADAMTS9-Mediated Extracellular Matrix Dynamics Regulates Umbilical Cord Vascular Smooth Muscle Differentiation and Rotation

Despite the significance for fetal nourishment in mammals, mechanisms of umbilical cord vascular growth remain poorly understood. Here, the secreted metalloprotease ADAMTS9 is shown to be necessary for murine umbilical cord vascular development. Restricting it to the cell surface using a gene trap allele, Adamts9(Gt), impaired umbilical vessel elongation and radial growth via reduced versican proteolysis and accumulation of extracellular matrix (ECM). Both Adamts9(Gt) and conditional Adamts9 deletion revealed that ADAMTS9 produced by mesenchymal cells acted non-autonomously to regulate smooth muscle cell (SMC) proliferation, differentiation, and orthogonal reorientation during growth of the umbilical vasculature. In Adamts9(Gt/Gt), we observed interference with PDGFRβ signaling via the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway, which regulates cytoskeletal dynamics during SMC rotation. In addition, we observed disrupted Shh signaling and perturbed orientation of the mesenchymal primary cilium. Thus, ECM dynamics is a major influence on umbilical vascular SMC fate, with ADAMTS9 acting as its principal mediator.

The extracellular protease stl functions to inhibit migration of v'ch1 sensory neuron during Drosophila embryogenesis

Proper migration of cells through the dense and complex extracellular matrix (ECM) requires constant restructuring of the ECM to allow cells to move forward in a smooth manner. This restructuring can occur through the action of extracellular enzymes. Among these extracellular enzymes is the ADAMTS (A Disintegrin And Metalloprotease with ThromboSpondin repeats) family of secreted extracellular proteases. Drosophila stl encodes an ADAMTS protease expressed in and around the peripheral nervous system (PNS) during embryogenesis. The absence of stl displayed one specific neuron, the v'ch1 sensory neuron, migrating to its target sooner than in wild type. During normal development, the v'ch1 sensory neuron migrates dorsally at the same time it is extending an axon ventrally toward the CNS. Surprisingly, in the absence of stl, the v'ch1 neuron migrated further dorsally as compared to the wild type at stage 15, but did not migrate past its correct target at stage 16, suggesting a novel role for this extracellular protease in inhibiting migration of this neuron past a certain point.

ADAMTS proteases in fertility

The reproductive organs are unique among adult organs in that they must undergo continual tissue remodelling as a key aspect of their normal function. The processes for persistent maturation and release of new gametes, as well as fertilisation, implantation, placentation, gestation and parturition involve cyclic development and regression of tissues that must continually regenerate to support fertility. The ADAMTS family of proteases has been shown to contribute to many aspects of the tissue morphogenesis required for development and function of each of the reproductive organs. Dysregulation or functional changes in ADAMTS family proteases have been associated with reproductive disorders such as polycystic ovarian syndrome (PCOS) and premature ovarian failure (POF). Likewise, proteolytic substrates of ADAMTS enzymes have also been linked to reproductive function. New insight into the roles of ADAMTS proteases has yielded a deeper understanding of the molecular mechanisms behind fertility with clinical potential to generate therapeutic targets to resolve infertility, develop biomarkers that predict dysfunction of the reproductive organs and potentially offer targets for development of non-hormonal male and female contraceptives.

Proteomic analysis reveals CACN-1 is a component of the spliceosome in Caenorhabditis elegans

Cell migration is essential for embryonic development and tissue formation in all animals. cacn-1 is a conserved gene of unknown molecular function identified in a genome-wide screen for genes that regulate distal tip cell migration in the nematode worm Caenorhabditis elegans. In this study we take a proteomics approach to understand CACN-1 function. To isolate CACN-1-interacting proteins, we used an in vivo tandem-affinity purification strategy. Tandem-affinity purification-tagged CACN-1 complexes were isolated from C. elegans lysate, analyzed by mass spectrometry, and characterized bioinformatically. Results suggest significant interaction of CACN-1 with the C. elegans spliceosome. All of the identified interactors were screened for distal tip cell migration phenotypes using RNAi. Depletion of many of these factors led to distal tip cell migration defects, particularly a failure to stop migrating, a phenotype commonly seen in cacn-1 deficient animals. The results of this screen identify eight novel regulators of cell migration and suggest CACN-1 may participate in a protein network dedicated to high-fidelity gonad development. The composition of proteins comprising the CACN-1 network suggests that this critical developmental module may exert its influence through alternative splicing or other post-transcriptional gene regulation.

Building and specializing epithelial tubular organs: the Drosophila salivary gland as a model system for revealing how epithelial organs are specified, form and specialize

The past two decades have witnessed incredible progress toward understanding the genetic and cellular mechanisms of organogenesis. Among the organs that have provided key insight into how patterning information is integrated to specify and build functional body parts is the Drosophila salivary gland, a relatively simple epithelial organ specialized for the synthesis and secretion of high levels of protein. Here, we discuss what the past couple of decades of research have revealed about organ specification, development, specialization, and death, and what general principles emerge from these studies.

A new Adamts9 conditional mouse allele identifies its non-redundant role in interdigital web regression

ADAMTS9 is the most conserved member of a large family of secreted metalloproteases having diverse functions. Adamts9 null mice die before gastrulation, precluding investigations of its roles later in embryogenesis, in adult mice or disease models. We therefore generated a floxed Adamts9 allele to bypass embryonic lethality. In this mutant, unidirectional loxP sites flank exons 5-8, which encode the catalytic domain, including the protease active site. Mice homozygous for the floxed allele were viable, lacked an overt phenotype, and were fertile. Conversely, mice homozygous for a germ-line deletion produced from the floxed allele by Cre-lox recombination did not survive past gastrulation. Hemizygosity of the deleted Adamts9 in combination with mutant Adamts20 led to cleft palate and severe white spotting as previously described. Previously, Adamts9 haploinsufficiency combined with either Adamts20 or Adamts5 nullizygosity suggested a cooperative role in interdigital web regression, but the outcome of deletion of Adamts9 alone remained unknown. Here, Adamts9 was conditionally deleted in limb mesoderm using Prx1-Cre mice. Unlike other ADAMTS single knockouts, limb-specific Adamts9 deletion resulted in soft-tissue syndactyly (STS) with 100% penetrance and concurrent deletion of Adamts5 increased the severity of STS. Thus, Adamts9 has both non-redundant and cooperative roles in ensuring interdigital web regression. This new allele will be useful for investigating other biological functions of ADAMTS9.

Cadherin 99C regulates apical expansion and cell rearrangement during epithelial tube elongation

Apical and basolateral determinants specify and maintain membrane domains in epithelia. Here, we identify new roles for two apical surface proteins - Cadherin 99C (Cad99C) and Stranded at Second (SAS) - in conferring apical character in Drosophila tubular epithelia. Cad99C, the Drosophila ortholog of human Usher protocadherin PCDH15, is expressed in several embryonic tubular epithelial structures. Through loss-of-function and overexpression studies, we show that Cad99C is required to regulate cell rearrangement during salivary tube elongation. We further show that overexpression of either Cad99C or SAS causes a dramatic increase in apical membrane at the expense of other membrane domains, and that both proteins can do this independently of each other and independently of mislocalization of the apical determinant Crumbs (Crb). Overexpression of Cad99C or SAS results in similar, but distinct effects, suggesting both shared and unique roles for these proteins in conferring apical identity.

Controlling cell shape changes during salivary gland tube formation in Drosophila

Any type of tubulogenesis is a process that is highly coordinated between large numbers of cells. Like other morphogenetic processes, it is driven to a great extent by complex cell shape changes and cell rearrangements. The formation of the salivary glands in the fly embryo provides an ideal model system to study these changes and rearrangements, because upon specification of the cells that are destined to form the tube, there is no further cell division or cell death. Thus, morphogenesis of the salivary gland tubes is entirely driven by cell shape changes and rearrangements. In this review, we will discuss and distill from the literature what is known about the control of cell shape during the early invagination process and whilst the tubes extend in the fly embryo at later stages.

The multiple, complex roles of versican and its proteolytic turnover by ADAMTS proteases during embryogenesis

Embryonic development is an exceptionally dynamic process, requiring a provisional extracellular matrix that is amenable to rapid remodeling, and proteolytic or non-proteolytic mechanisms that can remodel the major components of this matrix. Versican is a chondroitin-sulfate proteoglycan that forms highly hydrated complexes with hyaluronan and is widely distributed in the provisional matrix of mammalian embryos. It has been extensively studied in the context of cardiovascular morphogenesis, neural crest cell migration and skeletal development. Analysis of Vcan transgenic mice has established the requirement for versican in cardiac development and its role in skeletogenesis. The ADAMTS family includes several versican-degrading proteases that are active during remodeling of the embryonic provisional matrix, especially during sculpting of versican-rich tissues. Versican is cleaved at specific peptide bonds by ADAMTS proteases, and the cleavage products are detectable by neo-epitope antibodies. Myocardial compaction, closure of the secondary palate (in which neural crest derived cells participate), endocardial cushion remodeling, myogenesis and interdigital web regression are developmental contexts in which ADAMTS-mediated versican proteolysis has been identified as a crucial requirement. ADAMTS proteases are expressed coordinately and function cooperatively in many of these contexts. In addition to versican clearance, ADAMTS proteases generate a bioactive versican fragment containing the N-terminal G1 domain, which we have named versikine. This review promotes the view that the embryonic extracellular matrix has evolved not only to provide a permissive environment for embryo growth and morphogenesis, but through its dissolution to influence and regulate cellular processes.

Extracellular metalloproteinases in neural crest development and craniofacial morphogenesis

The neural crest (NC) is a population of migratory stem/progenitor cells that is found in early vertebrate embryos. NC cells are induced during gastrulation, and later migrate to multiple destinations and contribute to many types of cells and tissues, such as craniofacial structures, cardiac tissues, pigment cells and the peripheral nervous system. Recently, accumulating evidence suggests that many extracellular metalloproteinases, including matrix metalloproteinases (MMPs), a disintegrin and metalloproteinases (ADAMs), and ADAMs with thrombospondin motifs (ADAMTSs), play important roles in various stages of NC development. Interference with metalloproteinase functions often causes defects in craniofacial structures, as well as in other cells and tissues that are contributed by NC cells, in humans and other vertebrates. In this review, we summarize the current state of the field concerning the roles of these three families of metalloproteinases in NC development and related tissue morphogenesis, with a special emphasis on craniofacial morphogenesis.

Receptor guanylyl cyclase Gyc76C is required for invagination, collective migration and lumen shape in the Drosophila embryonic salivary gland

The Drosophila embryonic salivary gland is formed by the invagination and collective migration of cells. Here, we report on a novel developmental role for receptor-type guanylyl cyclase at 76C, Gyc76C, in morphogenesis of the salivary gland. We demonstrate that Gyc76C and downstream cGMP-dependent protein kinase 1 (DG1) function in the gland and surrounding mesoderm to control invagination, collective migration and lumen shape. Loss of gyc76C resulted in glands that failed to invaginate, complete posterior migration and had branched lumens. Salivary gland migration defects of gyc76C mutant embryos were rescued by expression of wild-type gyc76C specifically in the gland or surrounding mesoderm, whereas invagination defects were rescued primarily by expression in the gland. In migrating salivary glands of gyc76C mutant embryos, integrin subunits localized normally to gland-mesoderm contact sites but talin localization in the surrounding circular visceral mesoderm and fat body was altered. The extracellular matrix protein, laminin, also failed to accumulate around the migrating salivary gland of gyc76C mutant embryos, and gyc76C and laminin genetically interacted in gland migration. Our studies suggest that gyc76C controls salivary gland invagination, collective migration and lumen shape, in part by regulating the localization of talin and the laminin matrix.