scholarly journals Drosophila Neuronal Injury Follows a Temporal Sequence of Cellular Events Leading to Degeneration at the Neuromuscular Junction

2015 ◽  
Vol 9s2 ◽  
pp. JEN.S25516 ◽  
Author(s):  
Barron L. Lincoln ◽  
Sahar H. Alabsi ◽  
Nicholas Frendo ◽  
Robert Freund ◽  
Lani C. Keller
Keyword(s):  
Neuromuscular Junction ◽  
Model Organism ◽  
Structural Defects ◽  
Cellular Mechanisms ◽  
Post Injury ◽  
Ubiquitinated Proteins ◽  
Cellular Events ◽  
Molecular Events ◽  
Complex Signaling

Neurodegenerative diseases affect millions of people worldwide, and as the global population ages, there is a critical need to improve our understanding of the molecular and cellular mechanisms that drive neurodegeneration. At the molecular level, neurodegeneration involves the activation of complex signaling pathways that drive the active destruction of neurons and their intracellular components. Here, we use an in vivo motor neuron injury assay to acutely induce neurodegeneration in order to follow the temporal order of events that occur following injury in Drosophila melanogaster. We find that sites of injury can be rapidly identified based on structural defects to the neuronal cytoskeleton that result in disrupted axonal transport. Additionally, the neuromuscular junction accumulates ubiquitinated proteins prior to the neurodegenerative events, occurring at 24 hours post injury. Our data provide insights into the early molecular events that occur during axonal and neuromuscular degeneration in a genetically tractable model organism. Importantly, the mechanisms that mediate neurodegeneration in flies are conserved in humans. Thus, these studies have implications for our understanding of the cellular and molecular events that occur in humans and will facilitate the identification of biomedically relevant targets for future treatments.

scholarly journals Glial imaging during synapse remodeling at the neuromuscular junction

2008 ◽  
Vol 4 (4) ◽  
pp. 319-326 ◽  
Author(s):  
Yi Zuo ◽  
Derron Bishop
Keyword(s):  
Neuromuscular Junction ◽  
Schwann Cells ◽  
Synapse Formation ◽  
Ultrastructural Organization ◽  
Post Injury ◽  
Electron Microscopic ◽  
Cell Dynamics ◽  
Transmission Electron

Glia are an indispensable structural and functional component of the synapse. They modulate synaptic transmission and also play important roles in synapse formation and maintenance. The vertebrate neuromuscular junction (NMJ) is a classic model synapse. Due to its large size, simplicity and accessibility, the NMJ has contributed greatly to our understanding of synapse development and organization. In the past decade, the NMJ has also emerged as an effective model for studying glia–synapse interactions, in part due to the development of various labeling techniques that permit NMJs and associated Schwann cells (the glia at NMJs) to be visualized in vitro and in vivo. These approaches have demonstrated that Schwann cells are actively involved in synapse remodeling both during early development and in post-injury reinnervation. In vivo imaging has also recently been combined with serial section transmission electron microscopic (ssTEM) reconstruction to directly examine the ultrastructural organization of remodeling NMJs. In this review, we focus on the anatomical studies of Schwann cell dynamics and their roles in formation, maturation and remodeling of vertebrate NMJs using the highest temporal and spatial resolution methods currently available.

Abstract 448: Platelets Contribute to Arterial and Venous Thrombosis in vivo

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Maria Koellnberger ◽  
Marie-Luise von Bruehl ◽  
Wolfgang Bergmeier ◽  
Denisa Wagner ◽  
Nigel Mackman ◽  
...  
Keyword(s):  
Thrombus Formation ◽  
Venous Stasis ◽  
Industrialized Countries ◽  
Cellular Mechanisms ◽  
Venous Thrombus ◽  
Cellular Events ◽  
Promising Strategy ◽  
Novel Model ◽  
Differential Contribution

Background: Arterial (AT) and venous thromboses (VT) are the major causes of morbidity in industrialized countries. While the critical contribution of platelets to AT has been recognized, the molecular and cellular mechanisms that trigger the development of VT are not yet fully understood. Methods: We established a novel model of VT, where thrombus formation occurs after venous stasis in the absence of mechanical endothelial injury. In contrast to published models, our approach closely resembles the triggers that lead to VT in humans. The molecular and cellular events in VT were assessed using intravital and electron microscopy. In particular, we evaluated the differential contribution of platelets (pts) and leukocytes (lcs) to AT and VT. Results: We found that in AT pts adhere rapidly, whereas only few lcs are recruited. The loss of platelet P-Selectin reduced lc accumulation during AT, was associated with thrombus destabilization, but had no effect on pt adhesion/aggregation. The loss of GPIIb led to a complete lack of pt adhesion/aggregation in AT. While AT largely depends on pts, lc adhesion was the prominent initial phenomenon during VT and involved both P-selectin and Mac-1. P-Selectin−/− as well as Mac-1−/− mice showed a massive reduction in lc accumulation. The lack of P-Selectin was accompanied by a reduction of the thrombus size 48 hours after stasis and was only marginally reduced in Mac 1−/− mice, indicating that lc rolling is sufficient to promote VT. The expression of tissue factor by lcs played a pivotal role for VT. Accordingly, mice with reduced TF expression showed a dramatic reduction in venous thrombus size. In addition to TF-bearing lcs, pts were recruited to the vessel wall early in VT. Pt accumulation involved both the fibrinogen and the vWF receptor and was virtually abolished in mice lacking GPIIb or GPIbα. To our surprise, we observed that pts do not accumulate during VT but play a functional role. Reduced pt adhesion in mice lacking either GPIIb, GPIbα, or VWF was associated with a significant reduction in venous thrombus size. Conclusion: Together, we show that VT, unlike AT depends on the concerted action of both lcs and pts. Hence, targeting pt activation and adhesion might provide a promising strategy in the prophylaxis and treatment of VT.

scholarly journals C. elegans expressing D76N β2-microglobulin: a model for in vivo screening of drug candidates targeting amyloidosis

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Giulia Faravelli ◽  
Sara Raimondi ◽  
Loredana Marchese ◽  
Frederick A. Partridge ◽  
Cristina Soria ◽  
...  
Keyword(s):  
Genetic Model ◽  
Model Organism ◽  
Chemical Screening ◽  
C Elegans ◽  
Drug Candidates ◽  
Molecular Events ◽  
Wild Type Phenotype ◽  
Familial Form ◽  
Automated Phenotyping

AbstractThe availability of a genetic model organism with which to study key molecular events underlying amyloidogenesis is crucial for elucidating the mechanism of the disease and the exploration of new therapeutic avenues. The natural human variant of β2-microglobulin (D76N β2-m) is associated with a fatal familial form of systemic amyloidosis. Hitherto, no animal model has been available for studying in vivo the pathogenicity of this protein. We have established a transgenic C. elegans line, expressing the human D76N β2-m variant. Using the INVertebrate Automated Phenotyping Platform (INVAPP) and the algorithm Paragon, we were able to detect growth and motility impairment in D76N β2-m expressing worms. We also demonstrated the specificity of the β2-m variant in determining the pathological phenotype by rescuing the wild type phenotype when β2-m expression was inhibited by RNA interference (RNAi). Using this model, we have confirmed the efficacy of doxycycline, an inhibitor of the aggregation of amyloidogenic proteins, in rescuing the phenotype. In future, this C. elegans model, in conjunction with the INVAPP/Paragon system, offers the prospect of high-throughput chemical screening in the search for new drug candidates.

GENERATION OF TRANSGENIC MICE FOR IN VIVO DETECTION OF INSULIN-CONTAINING GRANULE EXOCYTOSIS AND QUANTIFICATION OF INSULIN SECRETION

2009 ◽  
Vol 02 (04) ◽  
pp. 397-405 ◽  
Author(s):  
JINLING LU ◽  
NATALIA GUSTAVSSON ◽  
QIMING LI ◽  
GEORGE K. RADDA ◽  
THOMAS C. SÜDHOF ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Transgenic Mice ◽  
Fluorescent Proteins ◽  
Secretory Granules ◽  
Cellular Mechanisms ◽  
Transgenic Mouse Line ◽  
Molecular Events ◽  
Insulin Secretion In Vitro

Insulin secretion is a complex and highly regulated process. Although much progress has been made in understanding the cellular mechanisms of insulin secretion and regulation, it remains unclear how conclusions from these studies apply to living animals. That few studies have been done to address these issues is largely due to the lack of suitable tools in detecting secretory events at high spatial and temporal resolution in vivo. When combined with genetically encoded biosensor, optical imaging is a powerful tool for visualization of molecular events in vivo. In this study, we generated a DNA construct encoding a secretory granule resident protein that is linked with two spectrally separate fluorescent proteins, a highly pH-sensitive green pHluorin on the intra-granular side and a red mCherry in the cytosol. Upon exocytosis of secretory granules, the dim pHluorin inside the acidic secretory granules became highly fluorescent outside the cells at neutral pH, while mCherry fluorescence remained constant in the process, thus allowing ratiometric quantification of insulin secretory events. Furthermore, mCherry fluorescence enabled tracking the movement of secretory granules in living cells. We validated this approach in insulin-secreting cells, and generated a transgenic mouse line expressing the optical sensor specifically in pancreatic β-cells. The transgenic mice will be a useful tool for future investigations of molecular mechanism of insulin secretion in vitro and in vivo.

The Mechanisms Behind the Biological Activity of Flavonoids

2019 ◽  
Vol 26 (39) ◽  
pp. 6976-6990 ◽  
Author(s):  
Ana María González-Paramás ◽  
Begoña Ayuda-Durán ◽  
Sofía Martínez ◽  
Susana González-Manzano ◽  
Celestino Santos-Buelga
Keyword(s):  
Gene Expression ◽  
Biological Activity ◽  
Phenolic Compounds ◽  
Intracellular Signaling ◽  
Molecular Mechanisms ◽  
Radical Scavenging ◽  
Model Organism ◽  
Stress Theory ◽  
Radical Scavenging Properties

: Flavonoids are phenolic compounds widely distributed in the human diet. Their intake has been associated with a decreased risk of different diseases such as cancer, immune dysfunction or coronary heart disease. However, the knowledge about the mechanisms behind their in vivo activity is limited and still under discussion. For years, their bioactivity was associated with the direct antioxidant and radical scavenging properties of phenolic compounds, but nowadays this assumption is unlikely to explain their putative health effects, or at least to be the only explanation for them. New hypotheses about possible mechanisms have been postulated, including the influence of the interaction of polyphenols and gut microbiota and also the possibility that flavonoids or their metabolites could modify gene expression or act as potential modulators of intracellular signaling cascades. This paper reviews all these topics, from the classical view as antioxidants in the context of the Oxidative Stress theory to the most recent tendencies related with the modulation of redox signaling pathways, modification of gene expression or interactions with the intestinal microbiota. The use of C. elegans as a model organism for the study of the molecular mechanisms involved in biological activity of flavonoids is also discussed.

scholarly journals Molecular and Cellular Mechanisms of Metformin in Cervical Cancer

Cancers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2545
Author(s):  
Ya-Hui Chen ◽  
Po-Hui Wang ◽  
Pei-Ni Chen ◽  
Shun-Fa Yang ◽  
Yi-Hsuan Hsiao
Keyword(s):  
Cervical Cancer ◽  
Potential Role ◽  
Treatment Options ◽  
Cellular Mechanisms ◽  
Anticancer Effects ◽  
Clinical Benefits ◽  
Underlying Mechanisms

Cervical cancer is one of the major gynecologic malignancies worldwide. Treatment options include chemotherapy, surgical resection, radiotherapy, or a combination of these treatments; however, relapse and recurrence may occur, and the outcome may not be favorable. Metformin is an established, safe, well-tolerated drug used in the treatment of type 2 diabetes; it can be safely combined with other antidiabetic agents. Diabetes, possibly associated with an increased site-specific cancer risk, may relate to the progression or initiation of specific types of cancer. The potential effects of metformin in terms of cancer prevention and therapy have been widely studied, and a number of studies have indicated its potential role in cancer treatment. The most frequently proposed mechanism underlying the diabetes–cancer association is insulin resistance, which leads to secondary hyperinsulinemia; furthermore, insulin may exert mitogenic effects through the insulin-like growth factor 1 (IGF-1) receptor, and hyperglycemia may worsen carcinogenesis through the induction of oxidative stress. Evidence has suggested clinical benefits of metformin in the treatment of gynecologic cancers. Combining current anticancer drugs with metformin may increase their efficacy and diminish adverse drug reactions. Accumulating evidence is indicating that metformin exerts anticancer effects alone or in combination with other agents in cervical cancer in vitro and in vivo. Metformin might thus serve as an adjunct therapeutic agent for cervical cancer. Here, we reviewed the potential anticancer effects of metformin against cervical cancer and discussed possible underlying mechanisms.

scholarly journals In Vivo Production of RNA Aptamers and Nanoparticles: Problems and Prospects

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1422
Author(s):  
Ousama Al Shanaa ◽  
Andrey Rumyantsev ◽  
Elena Sambuk ◽  
Marina Padkina
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Large Scale ◽  
Potential Model ◽  
Model Organism ◽  
Rna Aptamers ◽  
Early Stages ◽  
Near Future

RNA aptamers are becoming increasingly attractive due to their superior properties. This review discusses the early stages of aptamer research, the main developments in this area, and the latest technologies being developed. The review also highlights the advantages of RNA aptamers in comparison to antibodies, considering the great potential of RNA aptamers and their applications in the near future. In addition, it is shown how RNA aptamers can form endless 3-D structures, giving rise to various structural and functional possibilities. Special attention is paid to the Mango, Spinach and Broccoli fluorescent RNA aptamers, and the advantages of split RNA aptamers are discussed. The review focuses on the importance of creating a platform for the synthesis of RNA nanoparticles in vivo and examines yeast, namely Saccharomyces cerevisiae, as a potential model organism for the production of RNA nanoparticles on a large scale.

scholarly journals Hippocampal Interneurons are Required for Trace Eyeblink Conditioning in Mice

2021 ◽  
Author(s):  
Wei-Wei Zhang ◽  
Rong-Rong Li ◽  
Jie Zhang ◽  
Jie Yan ◽  
Qian-Hui Zhang ◽  
...  
Keyword(s):  
Eyeblink Conditioning ◽  
Pyramidal Cells ◽  
Conditioned Eyeblink ◽  
Cellular Mechanisms ◽  
Sustained Activity ◽  
Early Acquisition ◽  
Freely Moving ◽  
Trace Eyeblink Conditioning

AbstractWhile the hippocampus has been implicated in supporting the association among time-separated events, the underlying cellular mechanisms have not been fully clarified. Here, we combined in vivo multi-channel recording and optogenetics to investigate the activity of hippocampal interneurons in freely-moving mice performing a trace eyeblink conditioning (tEBC) task. We found that the hippocampal interneurons exhibited conditioned stimulus (CS)-evoked sustained activity, which predicted the performance of conditioned eyeblink responses (CRs) in the early acquisition of the tEBC. Consistent with this, greater proportions of hippocampal pyramidal cells showed CS-evoked decreased activity in the early acquisition of the tEBC. Moreover, optogenetic suppression of the sustained activity in hippocampal interneurons severely impaired acquisition of the tEBC. In contrast, suppression of the sustained activity of hippocampal interneurons had no effect on the performance of well-learned CRs. Our findings highlight the role of hippocampal interneurons in the tEBC, and point to a potential cellular mechanism subserving associative learning.

scholarly journals To Divide or Not to Divide? How Deuterium Affects Growth and Division of Chlamydomonas reinhardtii

Biomolecules ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 861
Author(s):  
Veronika Kselíková ◽  
Vilém Zachleder ◽  
Kateřina Bišová
Keyword(s):  
Cell Cycle ◽  
Chlamydomonas Reinhardtii ◽  
Cell Cycle Progression ◽  
Model Organism ◽  
Cycle Progression ◽  
Synchronous Cultures ◽  
Multiple Fission ◽  
First Choice ◽  
High Doses

Extensive in vivo replacement of hydrogen by deuterium, a stable isotope of hydrogen, induces a distinct stress response, reduces cell growth and impairs cell division in various organisms. Microalgae, including Chlamydomonas reinhardtii, a well-established model organism in cell cycle studies, are no exception. Chlamydomonas reinhardtii, a green unicellular alga of the Chlorophyceae class, divides by multiple fission, grows autotrophically and can be synchronized by alternating light/dark regimes; this makes it a model of first choice to discriminate the effect of deuterium on growth and/or division. Here, we investigate the effects of high doses of deuterium on cell cycle progression in C. reinhardtii. Synchronous cultures of C. reinhardtii were cultivated in growth medium containing 70 or 90% D2O. We characterize specific deuterium-induced shifts in attainment of commitment points during growth and/or division of C. reinhardtii, contradicting the role of the “sizer” in regulating the cell cycle. Consequently, impaired cell cycle progression in deuterated cultures causes (over)accumulation of starch and lipids, suggesting a promising potential for microalgae to produce deuterated organic compounds.

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