Trachea-Derived Dpp Controls Adult Midgut Homeostasis in Drosophila

1. Download : Download high-res image (217KB)
2. Download : Download full-size image

Highlights? Trachea-derived Dpp/Bmp is required for midgut homeostasis ? Dpp expressed in tracheal cells reach intestinal cells through visceral muscles ? Dpp signaling is activated in enterocytes (ECs) in the Drosophila adult midgut ? Dpp signaling stabilizes ECs to restrict intestinal stem cell proliferation     

Brassinosteroids Act as Regulators of Tracheary-Element Differentiation in Isolated Zinnia Mesophyll Cells

Uniconazole [S-3307; (E)-l-(4-chlorophenyl)-4,4-dimethyl-2-(l,2,4-triazol-l-yl)-l-penten-3-ol],a synthetic plant-growth retardant, inhibited the differentiationof isolated mesophyll cells of Zinnia elegans L. into trachearyelements (TEs) but had no effect on cell division when it wasadded to the culture medium at a concentration of 3.4 µM.In the presence of uniconazole, none of the cytological eventscharacteristic of the processes of TE differentiation, suchas aggregation of actin filaments, bundling of microtubulesor localized thickening and lignification of secondary walls,was observed. Uniconazole was effective when it was added tothe medium within 36 h after the start of culture. Brassinosteroids(0.2 nM brassinolide or 2 µM homobrassinolide), but notgibberellin A₃, counteracted the inhibitory effect of uniconazoleon TE differentiation. Brassinosteroids were most effectivewhen they were added to cultures between 24 and 30 h after thestart of culture. Exogenously applied brassinosteroids promotedTE differentiation. It is suggested that the synthesis of brassinosteroidsis essential for the differentiation of the cells into TEs andthat uniconazole inhibits this differentiation through its inhibitoryeffect on the biosynthesis of brassinosteroids. (Received May 9, 1991; )     

Label-Retaining Cells in the Adult Murine Salivary Glands Possess Characteristics of Adult Progenitor Cells

Radiotherapy is the primary treatment for patients with head and neck cancer, which account for roughly 500,000 annual cases worldwide. Dysfunction of the salivary glands and associated conditions like xerostomia and dysphagia are often developed by these patients, greatly diminishing their life quality. Current preventative and palliative care fail to deliver an improvement in the quality of life, thus accentuating the need for regenerative therapies. In this study, a model of label retaining cells (LRCs) in murine salivary glands was developed, in which LRCs demonstrated proliferative potential and possessed markers of putative salivary progenitors. Mice were labeled with 5-Ethynyl-2′-deoxyuridine (EdU) at postnatal day 10 and chased for 8 weeks. Tissue sections from salivary glands obtained at the end of chase demonstrated co-localization between LRCs and the salivary progenitor markers keratin 5 and keratin 14, as well as kit mRNA, indicating that LRCs encompass a heterogeneous population of salivary progenitors. Proliferative potential of LRCs was demonstrated by a sphere assay, in which LRCs were found in primary and secondary spheres and they co-localized with the proliferation marker Ki67 throughout sphere formation. Surprisingly, LRCs were shown to be radio-resistant and evade apoptosis following radiation treatment. The clinical significance of these findings lie in the potential of this model to study the mechanisms that prevent salivary progenitors from maintaining homeostasis upon exposure to radiation, which will in turn facilitate the development of regenerative therapies for salivary gland dysfunction.     

Systemic and local effect of the Drosophila headcase gene and its role in stress protection of Adult Progenitor Cells

During the development of a holometabolous insect such as Drosophila, specific group of cells in the larva survive during metamorphosis, unlike the other larval cells, and finally give rise to the differentiated adult structures. These cells, also known as Adult Progenitor Cells (APCs), maintain their multipotent capacity, differentially respond to hormonal and nutritional signals, survive the intrinsic and environmental stress and respond to the final differentiation cues. However, not much is known about the specific molecular mechanisms that account for their unique characteristics. Here we show that a specific Drosophila APC gene, headcase (hdc), has a dual role in the normal development of these cells. It acts at a systemic level by controlling the hormone ecdysone in the prothoracic gland and at the same time it acts locally as a tissue growth suppressor in the APC clusters, where it modulates the activity of the TOR pathway and promotes their survival by contributing in the regulation of the Unfolded Protein Response. We also show that hdc provides protection against stress in the APCs and that its ectopic expression in cells that do not usually express hdc can confer these cells with an additional stress protection. Hdc is the founding member of a group of homolog proteins identified from C. elegans to humans, where has been found associated with cancer progression. The finding that the Drosophila hdc is specifically expressed in progenitor cells and that it provides protection against stress opens up a new hypothesis to be explored regarding the role of the human Heca and its contribution to carcinogenesis.     

Characterization of TLX Expression in Neural Stem Cells and Progenitor Cells in Adult Brains

TLX has been shown to play an important role in regulating the self-renewal and proliferation of neural stem cells in adult brains. However, the cellular distribution of endogenous TLX protein in adult brains remains to be elucidated. In this study, we used immunostaining with a TLX-specific antibody to show that TLX is expressed in both neural stem cells and transit-amplifying neural progenitor cells in the subventricular zone (SVZ) of adult mouse brains. Then, using a double thymidine analog labeling approach, we showed that almost all of the self-renewing neural stem cells expressed TLX. Interestingly, most of the TLX-positive cells in the SVZ represented the thymidine analog-negative, relatively quiescent neural stem cell population. Using cell type markers and short-term BrdU labeling, we demonstrated that TLX was also expressed in the Mash1+ rapidly dividing type C cells. Furthermore, loss of TLX expression dramatically reduced BrdU label-retaining neural stem cells and the actively dividing neural progenitor cells in the SVZ, but substantially increased GFAP staining and extended GFAP processes. These results suggest that TLX is essential to maintain the self-renewing neural stem cells in the SVZ and that the GFAP+ cells in the SVZ lose neural stem cell property upon loss of TLX expression.Understanding the cellular distribution of TLX and its function in specific cell types may provide insights into the development of therapeutic tools for neurodegenerative diseases by targeting TLX in neural stem/progenitors cells.     

MicroRNAs在心血管自噬中的调节作用

自噬作为一种进化上高度保守的细胞降解途径,其调节异常与心血管疾病的发生、发展密切相关.研究显示,在心血管系统中,基础水平自噬对维持心肌正常收缩和传导至关重要,而在缺血/再灌注损伤和心力衰竭等心血管病理状态下,自噬水平明显增强.细胞自噬是一种多基因参与的复杂过程,近年来越来越多的证据表明,microRNAs(miRNAs)在心血管系统发育、正常生理功能维持以及不同心血管疾病(cardiovascular disease,CVDs)自噬中具有重要调节作用.本文通过对miRNAs与CVDs自噬调节方面的进展进行归纳,针对miRNAs对CVDs自噬的潜在机制进行总结,望为心血管疾病的诊断和治疗提供新的方向.     

Temporal Patterns of Gene Expression in the Antenna of the Adult Drosophila Melanogaster

The time course of gene expression in the adult fruit fly has been partially characterized by using enhancer trap and reporter gene constructs that mark 49 different genes. The relative intensity of the reporter protein in individual cells of the antennae was measured as a function of adult age. Most genes showed a graduated expression, and the intensity of expression had a reproducible and characteristic time course. Different genes displayed different temporal patterns of expression and more often than not the pattern of expression was complex. We found a number of genes having patterns that scaled with life span. In these cases the intensity of gene expression was found to be invariant with respect to biological time, when expressed as a fraction of the life span of the line. The scaling was observed even when life span was varied as much as threefold. Such scaling serves to (1) further demonstrate that deterministic mechanisms such as gene regulation act to generate the temporal patterns of expression seen during adult life, (2) indicate that control of these regulatory mechanisms is linked to life span, and (3) suggest mechanisms by which this control is accomplished. We have concluded that gene expression in the adult fly is often regulated in a fashion that allows for graduated expression over time, and that the regulation itself is changing throughout adult life according to some prescribed program or algorithm.     

Human Fetal Brain-Derived Neural Stem/Progenitor Cells Grafted into the Adult Epileptic Brain Restrain Seizures in Rat Models of Temporal Lobe Epilepsy

Cell transplantation has been suggested as an alternative therapy for temporal lobe epilepsy (TLE) because this can suppress spontaneous recurrent seizures in animal models. To evaluate the therapeutic potential of human neural stem/progenitor cells (huNSPCs) for treating TLE, we transplanted huNSPCs, derived from an aborted fetal telencephalon at 13 weeks of gestation and expanded in culture as neurospheres over a long time period, into the epileptic hippocampus of fully kindled and pilocarpine-treated adult rats exhibiting TLE. In vitro, huNSPCs not only produced all three central nervous system neural cell types, but also differentiated into ganglionic eminences-derived γ-aminobutyric acid (GABA)-ergic interneurons and released GABA in response to the depolarization induced by a high K⁺ medium. NSPC grafting reduced behavioral seizure duration, afterdischarge duration on electroencephalograms, and seizure stage in the kindling model, as well as the frequency and the duration of spontaneous recurrent motor seizures in pilocarpine-induced animals. However, NSPC grafting neither improved spatial learning or memory function in pilocarpine-treated animals. Following transplantation, grafted cells showed extensive migration around the injection site, robust engraftment, and long-term survival, along with differentiation into β-tubulin III⁺ neurons (∼34%), APC-CC1⁺ oligodendrocytes (∼28%), and GFAP⁺ astrocytes (∼8%). Furthermore, among donor-derived cells, ∼24% produced GABA. Additionally, to explain the effect of seizure suppression after NSPC grafting, we examined the anticonvulsant glial cell-derived neurotrophic factor (GDNF) levels in host hippocampal astrocytes and mossy fiber sprouting into the supragranular layer of the dentate gyrus in the epileptic brain. Grafted cells restored the expression of GDNF in host astrocytes but did not reverse the mossy fiber sprouting, eliminating the latter as potential mechanism. These results suggest that human fetal brain-derived NSPCs possess some therapeutic effect for TLE treatments although further studies to both increase the yield of NSPC grafts-derived functionally integrated GABAergic neurons and improve cognitive deficits are still needed.     

No Intestinal Stem Cell Regeneration after Complete Progenitor Ablation in Drosophila Adult Midgut

<正>Adult stem cells or progenitors are essential for maintaining the normal structure and function of adult tissues(i.e.,homeostasis).One of the best examples is the adult intestinal epithelium which is constantly renewed by the progeny of intestinal stem cells(ISCs).The proliferation and differentiation of adult stem cells must be tightly controlled in order to maintain resident tissue homeostasis.Mis-regulation of stem     

Dpp and Hh signaling in the Drosophila embryonic eye field.

We have analyzed the function of the Decapentaplegic (Dpp) and Hedgehog (Hh) signaling pathways in partitioning the dorsal head neurectoderm of the Drosophila embryo. This region, referred to as the anterior brain/eye anlage, gives rise to both the visual system and the protocerebrum. The anlage splits up into three main domains: the head midline ectoderm, protocerebral neurectoderm and visual primordium. Similar to their vertebrate counterparts, Hh and Dpp play an important role in the partitioning of the anterior brain/eye anlage. Dpp is secreted in the dorsal midline of the head. Lowering Dpp levels (in dpp heterozygotes or hypomorphic alleles) results in a 'cyclops' phenotype, where mid-dorsal head epidermis is transformed into dorsolateral structures, i.e. eye/optic lobe tissue, which causes a continuous visual primordium across the dorsal midline. Absence of Dpp results in the transformation of both dorsomedial and dorsolateral structures into brain neuroblasts. Regulatory genes that are required for eye/optic lobe fate, including sine oculis (so) and eyes absent (eya), are turned on in their respective domains by Dpp. The gene zerknuellt (zen), which is expressed in response to peak levels of Dpp in the dorsal midline, secondarily represses so and eya in the dorsomedial domain. Hh and its receptor/inhibitor, Patched (Ptc), are expressed in a transverse stripe along the posterior boundary of the eye field. As reported previously, Hh triggers the expression of determinants for larval eye (atonal) and adult eye (eyeless) in those cells of the eye field that are close to the Hh source. Eya and So, which are induced by Dpp, are epistatic to the Hh signal. Loss of Ptc, as well as overexpression of Hh, results in the ectopic induction of larval eye tissue in the dorsal midline (cyclopia). We discuss the similarities between vertebrate systems and Drosophila with regard to the fate map of the anterior brain/eye anlage, and its partitioning by Dpp and Hh signaling.     

Enhanced Nanomagnetic Gene Transfection of Human Prenatal Cardiac Progenitor Cells and Adult Cardiomyocytes

Magnetic nanoparticle-based gene transfection has been shown to be an effective, non-viral technique for delivery of both plasmid DNA and siRNA into cells in culture. It has several advantages over other non-viral delivery techniques, such as short transfection times and high cell viability. These advantages have been demonstrated in a number of primary cells and cell lines. Here we report that oscillating magnet array-based nanomagnetic transfection significantly improves transfection efficiency in both human prenatal cardiac progenitor cells and adult cardiomyocytes when compared to static magnetofection, cationic lipid reagents and electroporation, while maintaining high cell viability. In addition, transfection of adult cardiomyocytes was improved further by seeding the cells onto Collagen I-coated plates, with transfection efficiencies of up to 49% compared to 24% with lipid reagents and 19% with electroporation. These results demonstrate that oscillating nanomagnetic transfection far outperforms other non-viral transfection techniques in these important cells.     

Isolation and Large Scale Expansion of Adult Human Endothelial Colony Forming Progenitor Cells

This paper introduces a novel recovery strategy for endothelial colony forming progenitor cells (ECFCs) from heparinized but otherwise unmanipulated adult human peripheral blood within a mean of 12 days. After large scale expansion >1x10⁸ ECFCs can be obtained for further tests. Advantageously by using pHPL the contact of human cells with bovine serum antigens can be excluded. By flow cytometry and immunohistochemistry the isolated cells can be characterized as ECFC and their in vitro functionality to form vascular like structures can be tested in a matrigel assay. Further these cells can be subcutaneously injected in a mouse model to form functional, perfused vessels in vivo. After long term expansion and cryopreservation proliferation, function and genomic stability appear to be preserved. ^3,4This animal-protein free isolation and expansion method is easily applicable to generate a large quantity of ECFCs. Download video file.^{(144M, mp4)}     

Sodium Ions as Regulators of Transcription in Mammalian Cells

Biochemistry (Moscow) - The maintenance of an uneven distribution of Na+ and K+ ions between the cytoplasm and extracellular medium is the basis for the functioning of any animal cell. Changes in...