pinecone/core-2020-05-10-deduplication huggingface dataset:
Expression of Heparan Sulfate Proteoglycan (Perlecan) in the Mouse Blastocyst Is Regulated during Normal and Delayed Implantation

AbstractPrevious studies have shown that expression of the heparan sulfate proteoglycan, perlecan, on the external trophectodermal cell surfaces of mouse blastocysts increases during acquisition of attachment competence. However, it is not clear if this change in perlecan protein expression also is reflected at the level of perlecan mRNA expression. In the present investigation, the spatial and temporal patterns of perlecan mRNA expression in the mouse embryo during the periimplantation period were examined byin situhybridization and reverse transcriptase–polymerase chain reaction. In addition, a delayed implantation model was used to determine the expression of perlecan mRNA and protein in dormant and estrogen-activated hatched blastocysts. The results demonstrate that perlecan mRNA expression is low in morulae, but increases in Day 4 blastocysts, attaining maximal expression in Day 4.5 attachment-competent blastocysts. In contrast, perlecan mRNA is detected in both the dormant and estrogen-activated delayed blastocysts; however, within 12 hr of blastocyst activation by estrogen, both perlecan protein and heparan sulfate chain expression markedly increase. Taken together, these results suggest that during normal development perlecan mRNA expression increases with the acquisition of attachment competence. Moreover, perlecan protein expression also is attenuated during delayed implantation and appears to increase in response to nidatory estrogen, perhaps via the increased translation of preexisting perlecan mRNA
Mouse Vaginal Opening Is an Apoptosis-Dependent Process Which Can Be Prevented by the Overexpression of Bcl2

AbstractIn the mouse, opening of the vaginal cavity to the skin is a late event, occurring around the fifth week of life; it can be induced in sexually immature mice by β-estradiol injections. We have generated two lines of transgenic mice expressing the human Bcl2 protein in a variety of tissues. The vaginal cavity of the transgenic females remained permanently closed, a condition completely resistant to β-estradiol injections; this was accompanied by a considerable distension of the genital tract. Histologic studies of vaginal sections at the time of opening to the skin in normal mice showed, by the TUNEL method which detects nuclei with fragmented DNA characteristic of apoptosis, that this event coincides with extensive apoptosis in the lower part of the vaginal mucosa, a process prevented in the bcl2 transgenic mice, which express Bcl2 in suprabasal epithelial cells and in subepithelial cells of the vaginal mucosa. In contrast, two lines of mice bearing a Bcl2 transgene placed under the control of a K10 keratin promoter, whose expression is restricted to the suprabasal layers of the epidermis, had a normal phenotype. Eyelids’ formation and opening of the external ear canals, which also occur after birth in the mouse, were not altered in any of these transgenic lines; histological study of eye and ear sections at the time of these events failed to detect apoptosis. In conclusion, the tissue remodeling required to complete maturation of the mouse female genital tract at the time of puberty is an hormonally triggered apoptosis-dependent process
Formation of the Male Pronuclear Lamina inDrosophila melanogaster

AbstractUpon fertilization, a sperm nucleus reorganizes to become a male pronucleus. This reorganization includes breakdown and reformation of the nuclear envelope of the male pronucleus. In this study, we used a maternally encoded nuclear lamina protein, YA, in parallel with another lamina protein, lamin Dm, as probes to study the formation of the male pronuclear lamina inDrosophila melanogaster.Ectopically expressed YA is present in the nuclear envelopes of spermatocytes, but not in mature sperm, similar to endogenous lamin Dm. This suggests that the nuclear envelope ofDrosophilasperm differs from that of somatic cells. Upon fertilization, YA and lamin Dm are recruited to the periphery of the male-derived nucleus before or during the early stages of migration by the male pronucleus. Using a paternal effect mutation,snky,we found that recruitment of lamina proteins to the male pronucleus requires, and probably accompanies, reorganization of the sperm nucleus. In order to identify factors that affect the recruitment of nuclear lamina proteins to the male pronucleus, we examined the subcellular localization of YA and lamin Dm in mutant embryos defective for the function of either the male pronucleus (mh, K81,andpal) or both pronuclei (gnu, png,andplu). None of these mutations affect the recruitment of YA or lamin Dm to the male pronuclear envelope, suggesting that the mutations affect processes independent of, or after, reorganization of the nuclear envelope. Double mutant analyses betweenYaandgnusuggest that YA plays a role in the nuclear envelope permissive for rounds of DNA replication
Developmental Expression ofBrca2Colocalizes withBrca1and Is Associated with Proliferation and Differentiation in Multiple Tissues

AbstractGermline mutations in the putative tumor suppressor gene,BRCA1,predispose women to dramatically elevated risks of breast cancer, while germline mutations in the structurally unrelated gene,BRCA2,predispose both men and women to breast cancer. Recent studies have suggested an important developmental role for the murine homologue ofBRCA1in the regulation of proliferation and differentiation. At the present time, however, little is known about the developmental role ofBRCA2or the regulation of its expressionin vivo.We have determined the spatial and temporal pattern of expression of the murine homologue ofBRCA2during fetal development, in adult tissues, and in the mammary gland during postnatal development. Our results indicate thatBrca2mRNA expression is highest in proliferating cellular compartments, particularly those undergoing differentiation. In the breast,Brca2expression is developmentally regulated and is induced during puberty and pregnancy and as a result of parity. Surprisingly, in multiple fetal and adult tissues the spatial and temporal pattern ofBrca2mRNA expression is virtually indistinguishable from that ofBrca1,despite the fact that these genes display no homology. These observations suggest thatBrca2is involved in the processes of proliferation and differentiation in the mammary gland and other tissues, and thatBrca1andBrca2mRNA expression may be regulated by similar pathways and stimuli in multiple cell types. Interestingly, however, our analysis reveals thatBrca1andBrca2expression are differentially regulated during the development of specific endocrine target tissues, such as the testis during spermatogenesis and the breast during pregnancy. In addition, the ratio of mRNA expression in the mammary glands of adult females relative to adult males is significantly greater forBrca1than forBrca2.These observations imply thatBrca1andBrca2mRNA expression are differentially regulated by sex hormones. In order to test this hypothesis, we have analyzed the expression of these two breast cancer susceptibility genes in ovariectomized mice treated with 17β-estradiol and progesterone. Our results demonstrate that the up-regulation of mRNA expression in the breast by ovarian hormones is significantly greater forBrca1than forBrca2.These observations suggest that the gender-specific differences in phenotype associated with germline mutations inBRCA2versusBRCA1may be related to the differential regulation of these genes by sex hormones
Myoblast αvβ3 Integrin Levels Are Controlled by Transcriptional Regulation of Expression of the β3 Subunit and Down-regulation of β3 Subunit Expression Is Required for Skeletal Muscle Cell Differentiation

AbstractThe expression of αvβ3 integrin was examined in human skeletal muscle cells grownin vitro.The αv and β3 subunits showed different patterns of expression during myogenesis. Expression of the αv subunit did not change significantly during the growth and differentiation of muscle cells, whereas expression of the β3 subunit was markedly down-regulated at both the message and protein levels. Down-regulation of β3 subunit expression did not occur when cultures were treated with 5-bromo-2′-deoxyuridine to inhibit myoblast terminal differentiation, but did occur in cultures in which fusion was selectively inhibited by growth in EGTA-containing medium. These results suggest that the regulation of integrin β3 subunit expression is tightly coupled to the myogenic terminal differentiation program, but is not simply a consequence of membrane reorganization due to the fusion process. Several stably transfected lines of mouse C2 myoblasts were derived from cultures transfected with a cDNA encoding the complete human β3 integrin sequence under the control of the CMV promoter. Lines which constitutively expressed high levels of the human β3 integrin subunit did not fuse or biochemically differentiate, whereas lines expressing moderate levels of the β3 integrin subunit showed delayed fusion and differentiation. Lines expressing very low to undetectable levels of the human β3 integrin subunit exhibited unimpaired fusion and differentiation. Taken together these results suggest (i) that down-regulation of αvβ3 integrin normally occurs as part of the myogenic terminal differentiation program, (ii) that this is mediated by regulation of the expression of the β3 subunit, and (iii) that down-regulation of expression of the β3 integrin subunit appears essential for myoblast differentiation
Characterization of aDictyosteliumFactor That Acts Synergistically with DIF to Induce Terminal Stalk Cell Differentiation

AbstractThe differentiation ofDictyosteliumprestalk cells is induced by the chlorinated hexaphenone DIF-1 and their maturation into stalk cells at culmination occurs by activation of the cAMP-dependent protein kinase (PKA). Medium harvested from developingDictyosteliumcells will act synergistically with DIF-1 to induce prestalk cell differentiation in a low-density monolayer assay (Yamada and Okamoto, 1994). Using HPLC, we have partially purified from such conditioned medium an activity we term STIF (stalk-inducing factor). It is hydrophilic and of low molecular weight. There are multiple classes of prestalk cells, which are defined by their patterns of expression of theecmAandecmBgenes and that can be further subcategorized because they utilize different elements within the promoters of the two genes. We show that, in a monolayer assay, STIF acts synergistically with DIF-1 to induceecmBgene expression via promoter elements that are normally activated strongly only in cells that have entered the stalk tube and which are therefore committed to differentiate into stalk cells. The combination of STIF and DIF-1 also induces morphological maturation of prestalk cells into stalk cells but does not efficiently induce expression ofecmA:a gene that is selectively expressed in cells within the anterior, prestalk region of the slug. Inactivation of PKA, by cell type-specific expression of a dominant inhibitor, represses the action of STIF. These data suggest that STIF is an extracellular signal that acts to induce the terminal differentiation of stalk cells
The Role of Actin Filaments in Patterning theCaenorhabditis elegansCuticle

AbstractNematodes are covered by a cuticle with a prominent pattern of circumferentially oriented, parallel furrows. We report here that the pattern of furrows on the first larval cuticle ofCaenorhabditis elegans,which is secreted during embryogenesis, is coincident with a pattern of submembranous actin filament bundles in the epithelial cells that secrete the cuticle. We propose that the pattern of cortical actin filaments biases the growth of the epithelial cell membranes, creating a furrowed surface template for deposition of the first cuticle layer. This layer then detaches from the epithelial cell surface as additional, nonpatterned components of the cuticle are secreted. Furrows are present on the surfaces of each of the four larval cuticles inC. elegansand on the adult cuticle. We show that similar ordered arrays of actin filaments appear during each of the postembryonic molts when new cuticles are synthesized. Our analysis suggests that conditions or mutations that affect the pattern of cuticle furrows might cause primary defects in the cytoskeletal organization of the epithelial cells that secrete the cuticle
Cerebroglycan, a Developmentally Regulated Cell-Surface Heparan Sulfate Proteoglycan, Is Expressed on Developing Axons and Growth Cones

AbstractCerebroglycan is a glycosylphosphatidylinositol-linked integral membrane heparan sulfate proteoglycan found exclusively in the developing nervous system. In the rodent, cerebroglycan mRNA first appears in regions containing newly generated neurons and typically disappears 1 to several days later (Stippet al.,1994,J. Cell Biol.124:149–160). To gain insight into the roles that cerebroglycan plays in the developing nervous system, monospecific antibodies were prepared and used to localize cerebroglycan protein. In the rat, cerebroglycan was prominantly expressed on axon tracts throughout the developing brain and spinal cord, where it was found at times when axons are actively growing, but generally not after axons have reached their targets. Cerebroglycan was also found on neuronal growth cones bothin vivoandin vitro.Interestingly, cerebroglycan immunoreactivity was rarely seen in or around neuronal cell bodies. Indeed, by examining the hippocampus at a late stage in development—when most neurons no longer express cerebroglycan but newly generated granule neurons do—evidence was obtained that cerebroglycan is strongly polarized to the axonal, and excluded from the somatodendritic, compartment of neurons. The timing and pattern of cerebroglycan expression are consistent with a role for this cell-surface heparan sulfate proteoglycan in regulating the growth or guidance of axons
Insulin-like Growth Factor Binding Protein Gene Expression in the Pregnant Rat Uterus and Placenta

AbstractWhile the insulin-like growth factor (IGF) system plays a fundamental role in regulating embryonic and placental growth, the specific contributions of the six IGF binding proteins (IGFBPs 1–6) to these processes are not well understood. We here focus on IGFBP expression in the extraembryonic environment, which both supports and constrains embryonic growth, and have usedin situhybridization to determine sites of IGFBP mRNA synthesis in the pregnant rat uterus and placenta. We find that all IGFBPs are expressed in distinct, changing patterns in the uterine endometrium, at the decidual boundary, in the decidual vasculature, and in the myometrium during pregnancy. Within the endometrium, the most prominent change is that expression of IGFBP-1 begins in some, but not all, endometrial glands prior to implantation and then expands to include all secretory epithelia shortly after implantation. During the period of rapid decidual proliferation that follows implantation, IGFBP-3, -4, and -5 transcripts are all detected in a laminar array at the boundary between the decidua and the nondecidualized endometrium. In the decidual vasculature at Day (d) 8.0, both IGFBP-3 and IGFBP-4 mRNAs are detected in dilating blood vessels, with BP-3 most prominent in the antimesometrial plexus and BP-4 primarily at the mesometrial pole. Later (d11.5), all decidual vessels express high levels of IGFBP-3 and lower levels of IGFBP-4 mRNAs. Finally, changes in expression of several IGFBPs also occur within the myometrium during pregnancy. For example, IGFBP-2 is expressed in the inner circular layer shortly after implantation, and expression increases through late gestation. In contrast, IGFBP-5 hybridization occurs over both myometrial layers before implantation, but decreases in intensity and spatial distribution as pregnancy proceeds. Finally, and most strikingly, IGFBP-6 expression, barely detectable in the d7.0 myometrium, gradually increases until it is very strongly transcribed during the placental stages. Taken together, these observations suggest multiple roles for IGFBPs in supporting implantation, regulating the extent of decidualization, modulating local levels of vascular IGFs, and regulating uterine muscular growth
Inhibition of Chondrogenesis byWntGene Expressionin Vivoandin Vitro

AbstractThe Wnt family of secreted signaling proteins are implicated in regulating morphogenesis and tissue patterning in a wide variety of organ systems. SeveralWntgenes are expressed in the developing limbs and head, implying roles in skeletal development. To explore these functions, we have used retroviral gene transfer to expressWnt-1 ectopically in the limb buds and craniofacial region of chick embryos. Infection of wing buds at stage 17 and tissues in the head at stage 10 resulted in skeletal abnormalities whose most consistent defects suggested a localized failure of cartilage formation. To test this hypothesis, we infected micromass cultures of prechondrogenic mesenchymein vitroand found that expression ofWnt-1 caused a severe block in chondrogenesis.Wnt-7a, a gene endogenously expressed in the limb and facial ectoderm, had a similar inhibitory effect. Further analysis of this phenomenonin vitroshowed thatWnt-1 andWnt-7a had mitogenic effects only in early prechondrogenic mesenchyme, that cell aggregation and formation of the prechondrogenic blastema occurred normally, and that the block to differentiation was at the late-blastema/early-chondroblast stage. These results indicate that Wnt signals can have specific inhibitory effects on cytodifferentiation and suggest that one function of endogenous Wnt proteins in the limbs and face may be to influence skeletal morphology by localized inhibition of chondrogenesis
Multiple Ras Signals Pattern theDrosophilaOvarian Follicle Cells

AbstractDuringDrosophilaoogenesis, spatially restricted activity of the TORPEDO receptor tyrosine kinase first recruits follicle cells adjacent to the oocyte to a posterior cell fate and then specifies dorsal follicle cells. Another receptor tyrosine kinase, BREATHLESS, stimulates migration of the anterior follicle cells known as border cells. Since Ras is known to mediate many receptor tyrosine kinase effects, we have investigated the role of Ras in follicle cell fate determination, differentiation, and migration throughout oogenesis. Early ectopic Ras activity induced transient expression of posterior follicle cell markers in anterior follicle cells, but did not inhibit anterior differentiation. Later ectopic Ras activity inhibited anterior follicle cell differentiation but did not induce posterior marker expression. Complete transformation of anterior follicle cells to posterior follicle cells required early ectopic Ras activity in egg chambers where terminal differentiation of anterior cells was inhibited. These results suggest that,in vivoasin vitro,Ras can have diverse effects on different cells, but, in addition, Ras activity can have different effects on the same cells at different stages in their development
Sorting of the Initial Cell Types inDictyosteliumIs Dependent on thetipAGene

AbstractAbout 8 hr after the initiation of development inDictyostelium discoideum,a few randomly scattered cells express prestalk specific genes and subsequently sort out to the top of the aggregate where they form a tip. The tip elongates and forms the anterior of the migrating slug before differentiating into a stalk which supports the ball of spores in a mature fruiting body. Using REMI mutagenesis we isolated a mutant strain, AK244, in which the initial aggregate subdivides to give a highly papillated surface. This mutant fails to form slugs and appears to have a defect in sorting of prestalk cells. The disrupted gene,tipA,encodes a novel 83-kDa protein and is preferentially expressed in PST-O cells after the cell types have sorted out. Mutant strains that lack TipA express the prestalk-specific geneecmAat reduced levels and form very few spores. These defects cannot be overcome by developing the mutant cells in the presence of wild-type cells. Thus, TipA acts in a cell-autonomous manner at an early stage in development. Using strains carrying reporter constructs, we found that mutant cells expressing a prestalk marker remain dispersed in the aggregates. Prespore cells appear to sort such that the base is free of cells expressing cell-type-specific markers. Even after 20 hr of development, when wild-type cells are undergoing terminal differentiation, prestalk cells intipA−mutants form very small clumps, most of which fail to sort to the periphery or the tops of aggregates. ThetipAgene appears to play an essential role in the sorting of the initial cell types
Role of Basic FGF and Oxygen in Control of Proliferation, Survival, and Neuronal Differentiation in Carotid Body Chromaffin Cells

AbstractCrest-derived glomus cells of the carotid body (CB) are O2-sensitive chemoreceptors, which resemble sympathoadrenal (SA) chromaffin cells. In this study, we tested whether perinatal rat glomus cells are sensitive to basic fibroblast growth factor (bFGF)in vitroand whether their sensitivity is regulated by oxygen. In chemically defined medium, bFGF (1–100 ng/ml) caused a significant, dose-dependent increase in the number of surviving tyrosine hydroxylase-positive (TH+) glomus cells in embryonic (E17–E19) CB cultures, following a 48-hr exposure. Though basic FGF (10 ng/ml) appeared mitogenic for these cells, based on stimulation of bromodeoxyuridine (BrdU) uptake, it supported survival of only ∼60% of the initial TH+population, suggesting that significant cell death was occurring. This apparent cell loss in E17 cultures could be largely prevented by combined treatment with bFGF and low oxygen (6% O2). In contrast, in early postnatal (P1) cultures, glomus cell number was relatively unchanged over 48 hr under control conditions or in presence of mitogenic activity from either bFGF or low oxygen. However, combined treatment with both bFGF and low oxygen stimulated proliferation of P1 glomus cells such that by 48 hr the TH+population had increased to ∼1.5× the initial density. Basic FGF (10 ng/ml) also stimulated neurite outgrowth and neurofilament expression in E18–E19, but not P1–P3, glomus cells. In contrast to bFGF, treatment with nerve growth factor was ineffective. Taken together, these results suggest that bFGF and low oxygen are mitogens for perinatal CB chromaffin cells and interact cooperatively as survival factors. It is plausible that these mechanisms may operate to regulate chemoreceptor cell density, during the animal's transition fromin utero(hypoxic) toex utero(normoxic) life