pinecone/core-2020-05-10-deduplication huggingface dataset:
A Role for Rho-like GTPases in the Polarisation of Mouse Eight-Cell Blastomeres

AbstractPolarisation of cells during mouse preimplantation development first occurs within blastomeres at the eight-cell stage, as part of a process called compaction. Cell–cell contact mediated by the cell adhesion molecule uvomorulin (E-cadherin) and the activity of the microfilament cytoskeleton are important in the development of compaction, which is crucial for establishment of trophoblast and pluriblast (inner cell mass) lineages and for subsequent development. Members of the Rho family of p21 GTPases have been shown to regulate the organisation of the actin cytoskeleton and adhesion in other cell types. The potential role of these proteins in compaction was investigated. Inhibition of Rho withClostridium botulinumC3-transferase disturbed intercellular flattening at compaction and prevented cytocortical microfilament polarisation of eight-cell blastomeres, in contrast to cytochalasin D which inhibited only adhesion. Microinjection of a constitutively activated recombinant Rho protein into four-cell blastomeres induced cortical microfilament disruption and apical displacement of nuclei associated with polarised clustering of microtubules. Interblastomere adhesion was reduced and E-cadherin was aberrently clustered at remaining cell–cell contacts. Similarly, activated Cdc42 protein induced nuclear displacement with additional cytoplasmic actin bundle formation between nucleus and cell–cell contacts. The effects produced by both of the activated GTPase proteins are indicative of prematurely induced but aberrently organised polarity. These results suggest that Rho family GTPases are involved in the polarisation of early mouse blastomeres
Induction of Germinal Vesicle Breakdown in a Cell-Free Preparation from Starfish Oocytes

AbstractIncubation of isolated germinal vesicles in the homogenate from maturing starfish oocytes resulted in synchronous germinal vesicle breakdown (GVBD), and chromosome condensation and gathering within 30 min. GVBD in this cell-free system required aerobic conditions. The endogenous ATP-generation system was preserved in the homogenate and effective under aerobic conditions, and thus exogenous ATP was not added to the homogenate. Injection of the homogenate into immature starfish oocytes induced meiotic maturation without 1-methyladenine, indicating high activity of maturation-promoting factor (MPF) in the homogenate. MPF activity in the homogenate was stable for 2 h at room temperature, while it disappeared within 1 h in the supernatant prepared by centrifugation of the homogenate. This disappearance of MPF activity is regulated by cyclin B destruction, similar to that seenin vivo
The Role of Star in the Production of an Activated Ligand for the EGF Receptor Signaling Pathway

AbstractTheStargene is a member of the EGFR signaling pathway which has diverse functions throughoutDrosophiladevelopment. In order to investigate the protein distribution for Star, we have generated a polyclonal antibody. Here, we show that the Star protein is expressed perinuclearly in the early female germline and later is found in the oocyte cytoplasm. Star is expressed at low levels in other tissues. The subcellular localization of the protein has been determined when Star is overexpressed in the eye disc. Star is located in the nuclear and contiguous endoplasmic reticulum membranes. A functional assay in the wing disc demonstrates that Star expression can activate a nonprocessed membrane-bound form of the EGFR ligand Spitz and overexpression of Star in the eye disc promotes the formation of smaller Spitz proteins. Based on these results, we propose that the Star protein is likely to be involved in Spitz ligand processing
Intracellular Calcium Release Channel Expression during Embryogenesis

AbstractThe release of intracellular calcium (Ca2+) via either inositol 1,4,5-trisphosphate receptors (IP3R) or ryanodine receptors (RyR) activates a wide variety of signaling pathways in virtually every type of cell. In the present study we demonstrate that at early stages of development IP3R mRNA and functional IP3-gated Ca2+release channels are widely expressed in virtually all tissues in murine embryos. As organogenesis proceeds, more specialized RyR channels are expressed in many cell types and the triggering mechanisms for intracellular Ca2+release become more diverse to include IP3-dependent and voltage-dependent and Ca2+-induced Ca2+release. As development proceeds virtually all cell types continue to express IP3R channels but in excitable cells including skeletal and cardiac muscles the major Ca2+release channels are RyRs. This developmental switch from predominantly IP3-mediated to both IP3-mediated and IP3-independent pathways for intracellular Ca2+release is consistent with data showing that IP3R plays an important regulatory role in cellular proliferation and apoptosis, whereas RyR is required for other cellular functions including muscle contraction
Several Levels of EGF Receptor Signaling during Photoreceptor Specification in Wild-Type,Ellipse,and Null MutantDrosophila

AbstractDominantEllipsemutant alleles of theDrosophilaEGF receptor homologue (DER) dramatically suppress ommatidium development in the eye and induce ectopic vein development in the wing. Their phenotype suggests a possible role for DER in specifying the founder R8 photoreceptor cells for each ommatidium. Here we analyze the basis ofEllipsemutations and use them to probe the role of DER in eye development. We show thatElpmutations result from a single amino acid substitution in the kinase domain which activates tyrosine kinase activity and MAP kinase activation in tissue culture cells. Transformant studies confirmed that the mutation is hypermorphicin vivo,but the DER function was elevated less than by ectopic expression of the ligand spitz. Ectopic spi promoted photoreceptor differentiation, even in the absence of R8 cells. Pathways downstream of DER activation were assessed to explore the basis of these distinct outcomes.Elpmutations caused overexpression of theNotchtarget gene E(spl) mδ and required function ofNotchto suppress ommatidium formation. TheElpphenotype also depended on the secreted proteinargosand was reverted inElp aosdouble mutants. Complete loss of DER function in clones of null mutant cells led to delay in R8 specification and subsequently to loss of mutant cells. The DER null phenotype was distinct from that of eitherspitzorveinmutants, suggesting that a combination of these or other ligands was required for aspects of DER function. In normal development DER protein was expressed in most retinal cells, but at distinct levels. We used an antibody specific for diphospho-ERK as well as expression of the DER target geneargosto assess the pattern of DER activity, finding highest activity in the intermediate groups of cells in the morphogenetic furrow. However, studies of mutant genotypes suggested that this activity may not be required for normal ommatidium development. Since we saw distinct phenotypic effects of four different levels of DER activity associated with wild-type, null mutant,Elpmutant, or fully activated DER function, we propose that multiple thresholds separate several aspects of DER function. These include activation ofNsignaling to repress R8 specification, turning onargosexpression, and recruiting photoreceptors R1–R7. It is possible that during normal eye development these thresholds are attained by different cells, contributing to the pattern of retinal differentiation
IL-10 Is an Autocrine Inhibitor of Human Placental Cytotrophoblast MMP-9 Production and Invasion

AbstractDuring human placentation, fetal cytotrophoblast stem cells differentiate and then invade the uterine wall and its associated spiral arteries. This process anchors the placenta to the uterus and supplies maternal blood to the fetus. Cytotrophoblast invasionin vitrorequires the expression of matrix metalloproteinase-9 (MMP-9). Recently, we showed that cytotrophoblasts produce interleukin-10 (IL-10), a potent immunomodulatory cytokine that could have paracrine effects on the maternal immune system. IL-10 synthesis is dramatically downregulated after the first 12 h of culture, while MMP-9 secretion is rapidly upregulated and the cells acquire an invasive phenotype. These observations prompted us to investigate whether IL-10 is an autocrine regulator of cytotrophoblast MMP-9 production. We found that the cells expressed IL-10 receptor mRNA, suggesting that autocrine effects are possible. Adding recombinant IL-10 to cytotrophoblast cultures significantly decreased the cells' MMP-9 expression at both protein and mRNA levels, but did not affect mRNA levels of the tissue inhibitor of metalloproteinase-3. Thus, IL-10 may alter the proteinase/inhibitor balance. IL-10 treatment further caused a net decrease in MMP activity, thereby reducing cytotrophoblast invasiveness. An antibody that neutralized endogenous IL-10 function had the opposite effect in all experiments. Together, these data suggest that IL-10 is an autocrine inhibitor of cytotrophoblast MMP-9 activity and invasiveness
Patterning ofCaenorhabditis elegansPosterior Structures by theAbdominal-BHomolog,egl-5

AbstractTheCaenorhabditis elegansbody axis, like that of other animals, is patterned by the action ofHoxgenes. In order to examine the function of oneC. elegans Hoxgene in depth, we determined the postembryonic expression pattern ofegl-5, theC. elegansmember of theAbdominal-B Hoxgene paralog group, by means of whole-mount staining with a polyclonal antibody. A major site ofegl-5expression and function is in the epithelium joining the posterior digestive tract with the external epidermis. Patterning this region and its derived structures is a conserved function ofAbd-Bparalog group genes in other animals. Cells that initiateegl-5expression during embryogenesis are clustered around the presumptive anus. Expression is initiated postembryonically in four additional mesodermal and ectodermal cell lineages or tissues. Once initiated in a lineage,egl-5expression continues throughout development, suggesting that the action ofegl-5can be regarded as defining a positional cell identity. A variety of cross-regulatory interactions betweenegl-5and the next more anteriorHoxgene,mab-5, help define the expression domains of their respective gene products. In its expression in a localized body region, function as a marker of positional cell identity, and interactions with anotherHoxgene,egl-5resemblesHoxgenes of other animals. This suggests thatC. elegans, in spite of its small cell number and reproducible cell lineages, may not differ greatly from other animals in the way it employsHoxgenes for regional specification during development
The Neurotransmitter Noradrenaline Drivesnoggin-Expressing Ectoderm Cells to ActivateN-tubulinand Become Neurons

AbstractNeurotransmitters regulate neuronal function in the nervous system and modulation of their synthesis, release, and binding by immature neurons and their targets is a major part of nervous system development. We propose that the neurotransmitter noradrenaline regulates neuronal fate during neurulation, before neurons have differentiated. The ability of noradrenaline to induce a neural fate was tested in naive ectoderm caps cut from late blastula stageXenopusembryos. Noradrenaline (10−6M) did not switch onotx-2 or NCAM and did not induce the formation of cement glands. We conclude that noradrenaline cannot induce a neural fate. By contrast, 10−8M noradrenaline activatedN-tubulinin ectoderm caps expressing the neural inducing moleculenogginby the time intact siblings had become mid-neurulae. Methoxamine, a specific α-adrenergic receptor agonist, also activatedN-tubulininnoggin-expressing caps. The α-adrenergic receptor blocker prazosin inhibited both noradrenaline- and methoxamine-induced activation ofN-tubulin. The neurotransmitters dopamine and 5-HT did not activate expression ofN-tubulin. XA-1,Otx-2,X-Delta, andXotchtranscripts were not sensitive to noradrenaline.HoxB9, which indicates posteriorization, was not activated by noradrenaline. When intact siblings were at stage 27, many cells innoggin-expressing, noradrenaline-treated caps were stained by the neuron-specific mcAb3A10. We propose that noradrenaline is an important endogenous modulator of neuronal fate, drivingnoggin-expressing cells to become neurons by binding to α-adrenergic receptors and activating a cascade that culminates in the expression of the neuronal markersN-tubulinand 3A10
Myogenic Determination Occurs Independently in Somites and Limb Buds

AbstractGene targeting has indicated that the bHLH transcription factorsMyf-5andMyoDare required for myogenic determination because skeletal myoblasts and myofibers are entirely ablated in mouse embryos lacking bothMyf-5andMyoD. Entrance into the skeletal myogenic program during development occurs following the independent transcriptional induction of eitherMyf-5orMyoD. To identify sequences required for thede novoinduction ofMyoDtranscription during development, we investigated the expression patterns ofMyoD-lacZtransgenes in embryos deficient in bothMyf-5andMyoD. We observed that a 258-bp fragment containing the core of the −20-kbMyoDenhancer activated expression in newly formed somites and limb buds in compound mutant embryos lacking bothMyf-5andMyoD. Importantly,Myf-5-andMyoD-deficient presumptive muscle precursor cells expressing β-galactosidase were observed to assume nonmuscle fates primarily as precartilage primordia in the trunk and the limbs, suggesting that these cells were multipotential. Therefore, cells are recruited into theMyoD-dependent myogenic lineage through activation of the −20-kbMyoDenhancer and this occurs independently in somites and limb buds
Regulation of BMP Signaling by the BMP1/TLD-Related Metalloprotease, SpAN

AbstractWe have used theXenopusembryo as a test system for analyzing the activity of SpAN, a sea urchin metalloprotease in the astacin family containing BMP1 and tolloid. Embryos expressing SpAN initiated gastrulation on a time scale indistinguishable from controls, but invagination of the vegetal pole was subsequently delayed by several hours. At tailbud stages the most severely affected embryos were completely ventralized, lacking all dorsal structures. Molecular analysis of injected embryos, using probes for both dorsal (xgscandxnot) and ventral(xhox3andxwnt8) mesoderm, indicates that SpAN ventralizes dorsal mesoderm during gastrula stages. These results mirror those previously obtained with BMP4, suggesting that SpAN may enhance the activity of this ventralizing factor. Consistent with this suggestion, we have shown that SpAN blocks the dorsalizing activity of noggin and chordin, two inhibitory binding proteins for BMP4, but not that of a dominant-negative receptor for BMP4. In contrast, a dominant-negative SpAN, in which the metalloprotease domain has been deleted, dorsalizes ventral mesoderm, a phenotype that can be rescued by coexpressing either SpAN or XBMP1. This suggests that SpAN is mimicking aXenopusmetalloprotease responsible for regulating the activity ofXenopusBMPs during gastrulation. Moreover, our results raise the possibility that SpAN may function to facilitate BMP signaling in early sea urchin embryos
Distinctcis-Essential Modules Direct the Time–Space Pattern of thePax6Gene Activity

AbstractPax6is a regulatory gene with restricted expression and essential functions in the developing eye and pancreas and distinct domains of the CNS. In this study we report the identification of three conserved transcription start sites (P0, P1, α) in the murinePax6locus. Furthermore, using transgenic mouse technology we localized independentcis-regulatory elements controlling the tissue-specific expression ofPax6.Specifically, a 107-bp enhancer and a 1.1-kb sequence within the 4.6-kb untranslated region upstream of exon 0 are required to mediatePax6expression in the lens, cornea, lacrimal gland, conjunctiva, or pancreas, respectively. Another 530-bp enhancer fragment located downstream of thePax6translational start site is required for expression in the neural retina, the pigment layer of the retina, and the iris. Finally, a 5-kb fragment located between the promoters P0 and P1 can mediate expression into the dorsal telencephalon, the hindbrain, and the spinal cord. The identifiedPax6/cis-essential elements are highly conserved in pufferfish, mouse, and human DNA and contain binding sites for several transcription factors indicative of the cascade of control events. Corresponding regulatory elements from pufferfish are able to mimic the reporter expression in transgenic mice. Thus, the results indicate a structural and functional conservation of thePax6regulatory elements in the vertebrate genome
Expression ofvasa(vas)-Related Genes in Germline Cells and Totipotent Somatic Stem Cells of Planarians

AbstractPlanarians are known for their strong regenerative ability. This ability has been considered to reside in the totipotent somatic stem cell called the “neoblast.” Neoblasts contain a unique cytoplasmic structure called the “chromatoid body,” which has similar characteristics to the germline granules of germline cells of other animals. The chromatoid bodies decrease in number and size during cytodifferentiation and disappear in completely differentiated cells during regeneration. However, germ cells maintain the chromatoid body during their differentiation from neoblasts. These observations suggest that the chromatoid body is concerned with the totipotency of cells. To understand the molecular nature of the chromatoid body in the neoblast, we focused onvasa(vas)-related genes, since VAS and VAS-related proteins are known to be components of the germline granules inDrosophilaandCaenorhabditis elegans.By PCR, twovas-related genes (Dugesia japonica vasa-like gene, DjvlgAandDjvlgB) were isolated, and they were shown to be expressed in germ cells. Interestingly,DjvlgAwas also expressed in a number of somatic cells in the mesenchymal space. In regenerating planarians, accumulation ofDjvlgA-expressing cells was observed in both the blastema and the blastema–proximal region. In X-ray-irradiated planarians, which had lost regenerative capacity, the number ofDjvlgA-expressing cells decreased drastically. These results suggest that the product ofDjvlgAmay be a component of the chromatoid body and may be involved in the totipotency of the neoblast
Translational Recruitment ofXenopusMaternal mRNAs in Response to Poly(A) Elongation Requires Initiation Factor eIF4G-1

AbstractXenopusoocytes accumulate maternal mRNAs which are then recruited to ribosomes during meiotic cell cycle progression in response to progesterone and coincident with poly(A) elongation. Prior to stimulation, most protein synthesis (∼70%) does not require intact translation factor eIF4G (B. D. Keiper and R. E. Rhoads, 1997,Nucleic Acids Res.25, 395–402). In the present study we have addressed the requirement of eIF4G in the recruitment of mRNAs during meiosis. Cleavage of eIF4G by coxsackievirus protease 2A inhibited progesterone-induced meiotic progression in 88% of the oocytes; prevented the recruitment of maternal mRNAs encoding cyclin B1, c-Mos, D7, and B9; and disrupted the association of eIF4G with poly(A)-binding protein. Poly(A) elongation, however, was not inhibited by eIF4G cleavage. Injection of MPF restored meiotic cell cycle progression to >60% of the oocytes but not the recruitment of cyclin B1 or B9 mRNA. Previously recruited maternal mRNAs were removed from polyribosomes following subsequent cleavage of eIF4G, indicating that eIF4G is required both to recruit and also to maintain maternal mRNAs on polyribosomes. The expression of a cleavage-resistant variant of human eIF4G-1 (G486E) significantly restored the ability to synthesize c-Mos in response to progesterone and to translate exogenous β-globin mRNA, indicating that the inhibition by protease 2A is due to cleavage of eIF4G alone. These results indicate that intact eIF4G is required for the poly(A)-dependent recruitment of several maternal mRNAs (cyclin B1, c-Mos, D7, and B9) during meiotic cell cycle progression but not for the synthesis of most proteins
AP-2αTranscription Factor Is Required for Early Morphogenesis of the Lens Vesicle

AbstractAP-2transcription factors are a family of retinoic acid-responsive genes, which are involved in complex morphogenetic processes. In the current study, we determine the requirement forAP-2αin early morphogenesis of the eye by examining the nature of the ocular defects inAP-2αnull and chimeric mice.AP-2αnull embryos exhibited ocular phenotypes ranging from a complete lack of eyes (anophthalmia) to defects in the developing lens involving a persistent adhesion of the lens to the overlying surface ectoderm. Two genes involved in lens development and differentiation,Pax6and MIP26 were also misexpressed.AP-2αmutants also exhibited defects in the optic cup consisting of transdifferentiation of the dorsal retinal pigmented epithelium into neural retina and the absence of a defined ganglion cell layer. Newly generated chimeric embryos consisting of a population ofAP-2α−/−andAP-2α+/+cells exhibit ocular defects similar to those seen in the knockout embryos. Immunolocalization ofAP-2proteins (α, β, and γ) to the normal developing eye revealed both unique and overlapping expression patterns, withAP-2αexpressed in a number of the ocular tissues that exhibited defects in the mutants, including the developing lens whereAP-2αis uniquely expressed. Together these findings demonstrate a requirement forAP-2αin early morphogenesis of the eye
Human Mammary Luminal Epithelial Cells Contain Progenitors to Myoepithelial Cells

AbstractThe origin of the epithelial and myoepithelial cells in the human breast has not been delineated. In this study we have addressed whether luminal epithelial cells and myoepithelial cells are vertically connected, i.e., whether one is the precursor for the other. We used a primary culture assay allowing preservation of basic phenotypic traits of luminal epithelial and myoepithelial cells in culture. The two cell types were then separated immunomagnetically using antibodies directed against lineage-specific cell surface antigens into at best 100% purity. The cellular identity was ascertained by cytochemistry, immunoblotting, and 2-D gel electrophoresis. Luminal epithelial cells were identified by strong expression of cytokeratins 18 and 19 while myoepithelial cells were recognized by expression of vimentin and α-smooth muscle actin. We used a previously devised culture medium (CDM4) that allows vigorous expansion of proliferative myoepithelial cells and also devised a medium (CDM6) that allowed sufficient expansion of differentiated luminal epithelial cells based on addition of hepatocyte growth factor/scatter factor. The two different culture media supported each lineage for at least five passages without signs of interconversion. We used parallel cultures where we switched culture media, thus testing the ability of each lineage to convert to the other. Whereas the myoepithelial lineage showed no signs of interconversion, a subset of luminal epithelial cells, gradually, but distinctly, converted to myoepithelial cells. We propose that in the mature human breast, it is the luminal epithelial cell compartment that gives rise to myoepithelial cells rather than the other way around