Identification of Bipotential Blood Cell/Nephrocyte Progenitors in Another Route for Generating Blood Progenitors.

The lymph gland is the larval hematopoietic organ and is aligned along the anterior part of the cardiovascular system, composed of cardiac cells, that form the cardiac tube and its associated pericardial cells or nephrocytes. By the end of embryogenesis the lymph gland is composed of a single pair of lobes. Two additional pairs of posterior lobes develop during larval development to contribute to the mature lymph gland.

Intrinsic control of muscle attachment sites matching.

Myogenesis is an evolutionarily conserved process. Little known, however, is how the morphology of each muscle is determined, such that movements relying upon contraction of many muscles are both precise and coordinated. Each larval muscle is a single multinucleated fibre whose morphology reflects expression of distinctive identity Transcription Factors (iTFs).

Alary muscles and thoracic alary-related muscles are atypical striated muscles involved in maintaining the position of internal organs.

Alary muscles (AMs) have been described as a component of the cardiac system in various arthropods. Lineage-related thoracic muscles (TARMs), linking the exoskeleton to specific gut regions, have recently been discovered in Asymmetrical attachments of AMs and TARMs, to the exoskeleton on one side and internal organs on the other, suggested an architectural function in moving larvae. Here, we analysed the shape and sarcomeric organisation of AMs and TARMs, and imaged their atypical deformability in crawling larvae.

Dynamics of transcriptional (re)-programming of syncytial nuclei in developing muscles.

Background: A stereotyped array of body wall muscles enables precision and stereotypy of animal movements. In Drosophila, each syncytial muscle forms via fusion of one founder cell (FC) with multiple fusion competent myoblasts (FCMs). The specific morphology of each muscle, i.

Genetic dissection of the Transcription Factor code controlling serial specification of muscle identities in Drosophila.

Each Drosophila muscle is seeded by one Founder Cell issued from terminal division of a Progenitor Cell (PC). Muscle identity reflects the expression by each PC of a specific combination of identity Transcription Factors (iTFs). Sequential emergence of several PCs at the same position raised the question of how developmental time controlled muscle identity.

Hox control of Drosophila larval anatomy; The Alary and Thoracic Alary-Related Muscles.

The body plan of arthropods and vertebrates involves the formation of repetitive segments, which subsequently diversify to give rise to different body parts along the antero-posterior/rostro-caudal body axis. Anatomical variations between body segments are crucial for organ function and organismal fitness. Pioneering work in Drosophila has established that Hox transcription factors play key roles both in endowing initially identical segments with distinct identities and organogenesis.

An Org-1-Tup transcriptional cascade reveals different types of alary muscles connecting internal organs in Drosophila.

The T-box transcription factor Tbx1 and the LIM-homeodomain transcription factor Islet1 are key components in regulatory circuits that generate myogenic and cardiogenic lineage diversity in chordates. We show here that Org-1 and Tup, the Drosophila orthologs of Tbx1 and Islet1, are co-expressed and required for formation of the heart-associated alary muscles (AMs) in the abdomen. The same holds true for lineage-related muscles in the thorax that have not been described previously, which we name thoracic alary-related muscles (TARMs).

Angiogenin expression during early human placental development; association with blood vessel formation.

The placenta is a transient organ essential for fetal development. During human placental development, chorionic villi grow in coordination with a large capillary network resulting from both vasculogenesis and angiogenesis. Angiogenin is one of the most potent inducers of neovascularisation in experimental models in vivo.

Tup/Islet1 integrates time and position to specify muscle identity in Drosophila.

The LIM-homeodomain transcription factor Tailup/Islet1 (Tup) is a key component of cardiogenesis in Drosophila and vertebrates. We report here an additional major role for Drosophila Tup in specifying dorsal muscles. Tup is expressed in the four dorsal muscle progenitors (PCs) and tup-null embryos display a severely disorganized dorsal musculature, including a transformation of the dorsal DA2 into dorsolateral DA3 muscle.

Mesenchymal activin-A overcomes defective human trisomy 21 trophoblast fusion.

Placental development is markedly abnormal in trisomy 21 (T21) pregnancies. We hypothesized that abnormal paracrine cross talk between the fetal mesenchymal core and the trophoblast might be involved in the defect of syncytiotrophoblast formation and function. In a large series of primary cultured human cytotrophoblasts isolated from second-trimester control (n = 44) and T21 placentae (n = 71), abnormal trophoblast fusion and differentiation was observed in more than 90% of T21 cases.

Expression in Escherichia coli and purification of human recombinant connexin-43, a four-pass transmembrane protein.

We have recently shown, using a well-defined in vitro model, that connexin 43 (Cx43) is directly involved in human cytotrophoblastic cell fusion into a multinucleated syncytiotrophoblast. Cx43 appears to interact with partner proteins within a fusogenic complex, in a multi factorial and dynamic process. This fusogenic complex remains to be characterized and constituent proteins need to be identified.

Human trophoblast in trisomy 21: a model for cell-cell fusion dynamic investigation.

Trophoblastic cell fusion is one essential step of the human trophoblast differentiation leading to formation of the syncytiotrophoblast, site of the numerous placental functions. This process is multifactorial and finely regulated. Using the physiological model of primary culture of trophoblastic cells isolated from human placenta, we have identified different membrane proteins directly involved in trophoblastic cell fusion: connexin 43, ZO-1 and recently syncytins.

ZO-1 is involved in trophoblastic cell differentiation in human placenta.

Trophoblastic cell-cell fusion is an essential event required during human placental development. Several membrane proteins have been described to be directly involved in this process, including connexin 43 (Cx43), syncytin 1 (Herv-W env), and syncytin 2 (Herv-FRD env glycoprotein). Recently, zona occludens (ZO) proteins (peripheral membrane proteins associated with tight junctions, adherens junctions, and gap junctions) were shown to be involved in mouse placental development.

Trisomy 21- affected placentas highlight prerequisite factors for human trophoblast fusion and differentiation.

Trophoblastic cell fusion is one essential step of the human trophoblast differentiation pathway and is a multifactorial and dynamic process finely regulated and still poorly known. Disturbances of syncytiotrophoblast formation are observed in numerous pathological clinical conditions such as preeclampsia, intrauterine growth retardation and trisomy 21. In this review, we summarize current knowledge of the different membrane proteins directly involved in trophoblastic cell fusion, which we identified by using the physiological model of primary culture of villous trophoblastic cells.

Comparative methylation of ERVWE1/syncytin-1 and other human endogenous retrovirus LTRs in placenta tissues.

Human endogenous retroviruses (HERVs) are globally silent in somatic cells. However, some HERVs display high transcription in physiological conditions. In particular, ERVWE1, ERVFRDE1 and ERV3, three proviruses of distinct families, are highly transcribed in placenta and produce envelope proteins associated with placenta development.

Human endogenous retrovirus-FRD envelope protein (syncytin 2) expression in normal and trisomy 21-affected placenta.

Human trophoblast expresses two fusogenic retroviral envelope proteins, the widely studied syncytin 1, encoded by HERV-W and the recently characterized syncytin 2 encoded by HERV-FRD. Here we studied syncytin 2 in normal and Trisomy 21-affected placenta associated with abnormal trophoblast differentiation. Syncytin 2 immunolocalization was restricted throughout normal pregnancy to some villous cytotrophoblastic cells (CT).

Human placental development is impaired by abnormal human chorionic gonadotropin signaling in trisomy 21 pregnancies.

Placental development is markedly abnormal in women bearing a fetus with trisomy 21, with defective syncytiotrophoblast (ST) formation and function. The ST occurs from cytotrophoblast (CT) fusion and plays an essential role by secreting human chorionic gonadotropin (hCG), which is essential to placental development. In trisomy of chromosome 21 (T21) pregnancies, CTs do not fuse and differentiate properly into STs, leading to the secretion of an abnormal and weakly bioactive hCG.

Biochemical characterization and modulation of LH/CG-receptor during human trophoblast differentiation.

Due to the key role of the human chorionic gonadotropin hormone (hCG) in placental development, the aim of this study was to characterize the human trophoblastic luteinizing hormone/chorionic gonadotropin receptor (LH/CG-R) and to investigate its expression using the in vitro model of human cytotrophoblast differentiation into syncytiotrophoblast. We confirmed by in situ immunochemistry and in cultured cells, that LH/CG-R is expressed in both villous cytotrophoblasts and syncytiotrophoblasts. However, LH/CG-R expression decreased during trophoblast fusion and differentiation, while the expression of hCG and hPL (specific markers of syncytiotrophoblast formation) increased.

Short term Caco-2/TC7 cell culture: comparison between conventional 21-d and a commercially available 3-d system.

The Caco-2 cell model is a valuable tool for studying intestinal biotransformation of xenobiotics and to evaluate the potential of human intestinal absorption of new compounds. These properties were evaluated with Caco-2/TC7 cells in accelerated conditions to reduce maturation lag time from 21-d to 3-d in order to increase time and labor efficiency. Transmission electron and fluorescent microscopy were used for morphological characterization.

Angiogenin distribution in human term placenta, and expression by cultured trophoblastic cells.

Human angiogenin is a 14-kDa secreted protein with angiogenic and ribonucleolytic activities. Angiogenin is associated with tumour development but is also present in normal biological fluids and tissues. To further address the physiological role of angiogenin, we studied its expression in situ and in vitro, using the human term placenta as a model of physiological angiogenesis.

Large variability of trophoblast gene expression within and between human normal term placentae.

Human placenta extracts are widely used in clinical and fundamental research, particularly to study the hormonal and exchange functions of the placenta. However, very little is known about the distribution of the main hormone mRNAs in the placenta as a whole. Total placenta extracts are heterogeneous in their cellular components, as they contain material of both fetal and maternal origin, and in their structure.

Impact of trisomy 21 on human trophoblast behaviour and hormonal function.

Although trisomy 21 (T21) is the most frequent genetic abnormality and some maternal serum markers for this fetoplacental aneuploidy are of placental origin, little is known of its impact on placental development. We therefore studied the influence of T21 on trophoblast behaviour. Using cultured cells from 46 human T21 pregnancies, we confirmed the defective morphological and functional differentiation of the villous cytotrophoblast in this setting; indeed, villous cytotrophoblast cells aggregate normally but fuse inefficiently to form the syncytiotrophoblast.

Trophoblast production of a weakly bioactive human chorionic gonadotropin in trisomy 21-affected pregnancy.

Total human chorionic gonadotropin (hCG) is high in maternal serum at 14-18 wk of trisomy 21 (T21)-affected pregnancy, despite low placental hCG synthesis. We sought an explanation for this paradox. We first observed that, in T21-affected pregnancies, maternal serum hCG levels peaked at around 10 wk and then followed the same pattern throughout pregnancy as in controls, albeit at a higher (2.

A comparison of placental development and endocrine functions between the human and mouse model.

The placenta plays a key role in pregnancy, mediating exchanges between mother and fetus and maternal tolerance of fetopaternal antigens. In some species, it also produces hormones that ensure the maintenance of gestation and fetal well-being. This unique organ also has considerable potential for use as a model for various aspects of biology.

Involvement of connexin 43 in human trophoblast cell fusion and differentiation.

The syncytiotrophoblast is the principal component of the human placenta involved in feto-maternal exchanges and hormone secretion. The syncytiotrophoblast arises from the fusion of villous cytotrophoblasts. We recently showed that functional gap junctional intercellular communication (GJIC) is an important prerequisite for syncytiotrophoblast formation and that connexin 43 (Cx43) is present in cytotrophoblasts and in the syncytiotrophoblast.