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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Accurate splicing of HDAC6 requires Son

Battini, Vishnu Priya Chowdary January 2013 (has links)
No description available.
2

Complement protein C1q promotes macrophage autophagy during the clearance of atherogenic lipoproteins

Budin, Ryan 23 December 2016 (has links)
<p> Innate immune protein C1q plays a dual role in atherosclerosis. In early stages, C1q plays a protective role, but the mechanism is not fully understood. Autophagy is a catabolic pathway that has shown to play a role in cellular survival and is an important process in many phagocytic cells, such as macrophages. We hypothesize that complement C1q increases autophagy in macrophages during clearance of modified lipoprotein and acts in an atheroprotective manner to increase macrophage survival. We examined the influence of C1q on macrophage autophagy markers Atg5, Beclin 1, LC3B-II, and p62 during clearance of oxidized LDL. Levels of initiation and elongation protein, Beclin 1 and Atg5, are not modulated by C1q, but levels of autophagosome proteins, LC3B-II and p62, were increased in immunoblot. Quantitative PCR revealed that the increase in p62 protein levels was not due to an increase in transcription. Immunofluorescence microscopy verified that the increase in LC3B and p62 by C1q resulted in an increase in autophagosome formation during oxLDL and acLDL clearance. TEM verified the formation of double membrane vesicles. By inhibiting autolysosome maturation with chloroquine during modified LDL clearance, C1q modulation of autophagy was found to not have an effect on macrophage survival. These findings further our knowledge of C1q protective mechanisms, and the goal of developing future atherosclerosis therapies.</p>
3

Mechanisms that drive cardiomyocyte proliferation during zebrafish heart regeneration

Gemberling, Matthew P. January 2014 (has links)
<p>Heart disease is the leading cause of death in the developed world. Adult mammals cannot replace lost cardiac tissue after injury, leading to reduced quality of life and increased instances of future cardiac issues. Zebrafish possess the ability to regenerate lost cardiac muscle after injury. Upon injury, the zebrafish heart responds in a coordinated fashion resulting in activation of the epicardium and endocardium, cardiomyocyte proliferation, and subsequent vascularization and innervation of the newly formed muscle. Thus zebrafish represent an ideal genetic model to dissect the mechanisms of heart regeneration. Previously, it was discovered that regulatory sequences of the cardiac transcription factor, gata4, become active in the ventricular wall following injury and that these gata4+ cardiomyocytes proliferate and contribute the majority of new muscle to the regenerate. We uncovered that gata4 function is required for cardiomyocyte proliferation and regeneration after injury. Cardiomyocyte proliferation is required to achieve proper regeneration and lack of cardiomyocyte proliferation is a hallmark of failed regeneration in the mammalian system. Therefore, understanding the signals that induce mature cardiomyocyte division is of great scientific and clinical relevance. Utilizing transgenic approaches, we have found that gata4 function and Nrg1 signaling are critical regulators of cardiomyocyte proliferation. We found that Nrg1 was expressed following injury in the zebrafish heart and that inhibition of nrg1-erbb signaling blunted cardiomyocyte proliferation. Using transgenic over-expression of Nrg1, we found that Nrg1 was capable of increasing injury-induced cardiomyocyte proliferation. Furthermore we found that activation of Nrg1 in the uninjured adult heart induces cardiomyocyte proliferation and hallmarks of the regenerative program. Long-term nrg1 expression leads to patterned hyperplastic expansion of the zebrafish ventricle. To our knowledge, this is the first description of a single factor that is sufficient to induce such a dramatic hyperplastic response in an adult heart.</p> / Dissertation
4

Induction of Mitotic Alterations by the Human Papillomavirus Type 16 E7 Oncoprotein: Mechanistic Studies

Yu, Yueyang January 2013 (has links)
High-risk human papillomaviruses (HPVs) are causative agents of most cervical cancers and a significant portion of other anogenital tract and oral carcinomas. The major oncogenic activities of HPV16 E6 and E7 oncoproteins are associated with the degradation of the p53 and retinoblastoma tumor suppressors, respectively. E6 also causes increased expression of the catalytic subunit of telomerase, hTERT. In addition, E6 and E7 contribute to carcinogenesis through induction of genomic instability. Accurate chromosome segregation during mitosis is essential for preservation of genomic stability and HPV16 E7 perturbs mitosis in several ways. HPV16 E7 induces the synthesis of supernumerary centrosomes and increases the incidence of multipolar mitoses, which can lead to chromosome missegregation. Moreover, HPV16 E7 expression causes a prometaphase delay, which usually reflects an activation of the mitotic spindle assembly checkpoint (SAC), yet some studies suggested that the SAC is abrogated in HPV16 E7-expressing cells.
5

Filopodia-independent roles of the actin bundling protein fascin in promoting cell motility

Oak, Youbean 22 October 2014 (has links)
Fascin is an actin bundling protein whose overexpression has in recent years been systematically linked to increased metastasis and poor outcome in cancer patients. It is well established that fascin expression correlates with enhanced cell migration; however, the underlying mechanisms are poorly understood. We combined various methods of high-resolution live cell imaging and computational analysis to investigate the role of fascin in increasing cell motility. We found that fascin promotes collective migration in normal epithelial cells and that this behavior is in agreement with protrusive activities at the single cell level. Traction force measurements indicated that fascin expression level is negatively correlated with traction stress levels and that a cell expressing high levels of fascin protrudes over longer distances than cells with lower levels. Together this led to the hypothesis that fascin distributes cell traction more efficiently, which lowers the load on individual adhesions and actin filaments growing against increasing membrane tension during one protrusion cycle. Measurements of adhesion formation and maturation indicate that fascin expression indeed promotes nascent adhesion formation over a wide area behind the leading edge. In metastatic cells with high fascin expression, we observed decreased invasion upon fascin knock down. These observations demonstrate a role for fascin in promoting cell motility in normal and neoplastic cells, in part by templating nascent adhesions at the leading edge.
6

Yeast Env9 is a conserved oxidoreductase involved in lipid droplet biogenesis

Siddiqah, Ikha M. 22 August 2015 (has links)
<p> Baker&rsquo;s yeast serves as an ideal model to study endomembrane system due to high conservation of its regulation and trafficking between yeast and human. <i>ENV9</i> is a novel gene involved in vesicular trafficking in <i>Saccharomyces cerevisiae.</i> Previous characterization by our laboratory established that <i>ENV9</i> deletion leads to lysosomal defects and that Env9 is localized to lipid droplets (LDs). Our bioinformatics studies show that <i>ENV9</i> is conserved among eukaryotes and is an orthologue of human Retinol Dehydrogenase 12 (<i> RDH12</i>). </p><p> In this study, we show that Env9 is involved in LD biogenesis by positively regulating LD fusion and glycerol-induced LD proliferation. We establish Env9 to be an oxidoreductase <i>in vitro</i> that displays specific oxidoreductase activity towards RDH12 toxic aldehyde substrate. We also show that Env9 oxidoreductase activity requires its conserved functional domains. Furthermore, we show that oxidoreductase activity is essential for the observed cellular function of Env9 and that interactions with <i>ENV10</i> may be required for <i> ENV9</i>-dependent promotion of LD fusion.</p>
7

Cytoskeletal Dynamics and the Temporal Control of Yeast Morphogenesis

Chen, Hsin January 2012 (has links)
<p>The cells of the budding yeast Saccharomyces cerevisiae undergo a robust morphological cycle, involving reorganization of the actin cytoskeleton, septin ring formation, and polarized growth. These events are crucial to the formation of a fully-equipped and properly-shaped bud, which gives rise to the daughter cell. The budding yeast, as a well-established genetic model system, has attracted numerous investigations aimed at uncovering the underlying principles of morphogenesis. </p><p>Despite the important roles of the septin ring and collar in morphogenesis and cytokinesis, little is known about how they are assembled. We found that septins are recruited to the ring and collar following a tri-linear assembly/disassembly scheme. </p><p>Polarization of actin cables enable directed secretion and growth. The formin Bni1p, an actin nucleator, is thought to polarize actin cables in response to the direct regulation by the master polarity regulator, Cdc42p. However, we found that all the known Bni1p-regulatory pathways are dispensable, including the direct regulation by Cdc42p, and we uncovered a novel pathway linking Bni1p to Cdc42p via the Cdc42p effector, Gic2p.</p><p>Yeast morphogenesis is tightly coupled with the cell cycle. Contrary to the prevailing model, we found that G1-CDK activity, albeit required for bud emergence, is not needed to trigger polarization. This finding suggests that cells are in a default polarized state, which is negatively regulated by the G2-CDK.</p> / Dissertation
8

Adiporedoxin, an upstream modulator of endoplasmic reticulum oxidative folding and protein secretion

Laflamme, Collette 04 March 2016 (has links)
Our laboratory identified Adiporedoxin (Adrx), an endoplasmic reticulum localized oxidoreductase whose expression in adipose tissue is many fold greater than other tissues. In gain and loss of function experiments in cultured adipocytes Adrx knock down decreased the secretion of numerous adipokines, extracellular matrix, and transmembrane proteins and over expression increased secretion. Together, these results suggest Adrx regulates an early step in protein secretion from the ER. Immunofluorescence and proteolytic protection assays demonstrated that Adrx is located in the ER membrane with an ER luminal active site. We demonstrated that Adrx regulated protein secretion by affecting the oxidation state of ER redox chaperones. Using a cysteine-modifying PEGylation reagent, we showed Adrx oscillated between a reduced and oxidized form through the -CxxC- active site residues in response to the redox environment of the ER. Consequently, knocking down Adrx impaired the re-oxidation of protein disulfide isomerase, indicating an overlapping function with known regulators of ER redox homeostasis, namely endoplasmic reticulum oxidoreductase 1, and peroxiredoxin 4. Adrx is oxidized within the ER after treatment with hydrogen peroxide (H2O2) and can reduce H2O2 in vitro, suggesting it also acts as an antioxidant. The overexpression of Adrx in adipocytes protected the ER from oxidative stress and rescued adipokine secretion. Pancreatic islets are also highly secretory Adrx is expressed in isolated murine islets. In cultured islet cells, Adrx expression also decreased oxidative stress and correlated with the secretion of insulin, the main regulator of glucose homeostasis. In summary, Adrx expression controls secreted proteins and here we describe its ability to regulate the formation and release of disulfide-bonded proteins by reoxidizing ER chaperones and alleviating oxidative stress. Secreted proteins affect many aspects of metabolism including the control of appetite, glucose homeostasis, inflammation, and adipose tissue fibrosis. Overall, these data suggest that by mediating secreted proteins Adrx functions as important regulator of overall metabolism. / 2017-03-03T00:00:00Z
9

Defining YAP/TAZ-dependency in human breast cancer cells

Vakhshoorzadeh, Jasmine 20 June 2016 (has links)
OVERVIEW: Hyperactivation and amplification of the oncogenic transcriptional co-factors YAP and TAZ are common in breast cancer. However, it is unknown if breast cancer cells are dependent on YAP/TAZ for growth and survival. In addition, key transcriptional targets of YAP/TAZ that enable breast cancer growth have yet to be defined. To address these unresolved questions, we will define YAP/TAZ-dependencies across a large cohort of breast cancer cells and generate gene expression signatures for both YAP/TAZ-dependent and YAP/TAZ-independent lines. We aim to identify YAP/TAZ-target genes that are essential for the growth and survival of YAP/TAZ-dependent breast cancer cells. This approach may reveal genetic dependencies in breast cancer that can then be therapeutically exploited. METHODS: A comprehensive cohort of breast cancer cells (45 cell lines) was obtained from the American Type Culture Collection (ATCC). The majority of time allotted for this thesis was spent culturing and expanding the cell lines. Five complete breast cancer cell line libraries were successfully generated and annotated. These libraries will be a useful resource for the Boston University School of Medicine Cancer Research Community. Protein and RNA extracts were collected from all cell lines. RNA extraction was performed in all cell lines with the Qiagen RNase Kit as per the manufacturer’s instructions. Protein extracts were collected from the cell lines with RIPA lysis buffer. Protein lysates were then run on an acrylamide gel and the relative abundance of YAP and TAZ was quantified. RNA extracts were sent for microarray analysis to obtain gene expression profiles. Cell lines were also fixed and stained for YAP and TAZ at subconfluence (50%) and confluence (90%) and visualized through immunofluorescence to assess the relative subcellular localization of YAP and TAZ. RESULTS: Our results indicate that YAP/TAZ levels and activity are highly variable across breast cancer cell lines. Seven cell lines were found to overexpress only YAP, nineteen cell lines were found to overexpress only TAZ, and two cell lines (BT-474 and HCC 1599) were found to overexpress both YAP and TAZ. Two cell lines (MDA-MB-134-VI and DU4475) had negligible protein expression levels of YAP/TAZ. We were also able to identify a subset of cells as being resistant to Hippo pathway activation, as seen in MCF 10A, MCF 10F, and MCF-12A cells, which maintained nuclear YAP and TAZ even under confluent conditions, and with MDA-MB-231 cells, which maintained only nuclear YAP under confluence. Given the importance of YAP and TAZ in cellular proliferation and survival, these results suggest that these Hippo pathway inactive cell lines may be dependent on YAP and TAZ for survival, which will be assessed at a future time point. We plan to complete our analysis of the subcellular localization of YAP and TAZ for all 45 breast cancer cell lines. Microarray profiling and gene expression signature analysis of all 45 cell lines are also ongoing. DISCUSSION: We surmise that increased levels/activity of YAP/TAZ will predict increased dependency on these oncogenes for growth and survival. This prediction will be directly tested by assessing cell viability following YAP/TAZ knockdown experiments. We also hypothesize that YAP/TAZ-dependent cells will be dependent on the transcription of specific YAP/TAZ target genes for survival. Current work detailed in this thesis will form the foundation for future work focusing on therapy-relevant YAP/TAZ target genes that are critical to breast cancer pathogenesis and disease progression. Our long-term aim is to identify pharmacologically-tractable YAP/TAZ target genes with the ultimate goal of finding novel chemotherapeutics that will improve prognosis for breast cancer patients.
10

Comparison of downstream data quality of two differential extraction techniques through the examination of peak heights and peak height ratios

Sutherby, Danielle Marie 03 November 2016 (has links)
Analysis of sexual assault evidence in a forensic laboratory setting requires accurate analysis of deoxyribonucleic acid (DNA) utilizing forensic DNA typing. This process can be complicated since most sexual assault samples are comprised of DNA from a female contributor as well as one or more male contributors. Generally female epithelial cells (e-cells) are in excess, making it more difficult to determine the short tandem repeat (STR) profile of the male contributor from the significantly fewer sperm cells present in the mixture. This complexity requires that the two contributing sources of DNA be separated in order to obtain a probative single source profile. Separation of the two fractions is accomplished by differential extraction. The most common protocol for a differential extraction involves preferentially lysing epithelial cells while leaving the sperm cells intact, separating the released female DNA from the sperm cells and finally lysing the sperm cells to obtain the sperm fraction. Research has shown that a Trypsin-ZyGEM extraction method produces higher yields of DNA compared to the standard differential extraction method. A previous study examined whether substrate type had an effect on the efficiency of the Trypsin-ZyGEM extraction. It was found that the Trypsin-ZyGEM protocol worked well at extracting DNA from aqueous semen, dried semen in a microfuge tube and semen dried on white cotton. However, results were inconclusive on the method’s ability to extract DNA from semen dried on denim fabric due to inhibition of the quantitative polymerase chain reaction (qPCR) used to quantify the samples. In this study, a subset of the denim samples was amplified and processed through capillary electrophoresis to verify that the extraction protocol had successfully recovered DNA from this substrate type and that the DNA could be amplified to create a STR profile. Full profiles were obtained for all three of the denim samples that were amplified to a target mass of 1 nanogram (ng). One full profile and two partial profiles were obtained for the same samples at a target mass of 0.25ng. Allelic dropout for the partial profiles varied with one profile having 3 alleles dropout while the other had 11 dropout. Peak heights and peak height ratios were more variable compared to the other substrate types but were still within an acceptable range for probative profiles. The results are promising and suggest that the Trypsin-ZyGEM protocol could possibly replace the current differential extraction technique. Further research is required to understand if this extraction protocol would be efficient on these substrate types with mixture samples of semen and e-cells. This research also builds upon the exploration of the effectiveness of the Trypsin-ZyGEM extraction on dried and aqueous semen samples compared to a modified Qiagen differential extraction. Samples that had been previously quantified were amplified and separated by size using capillary electrophoresis. Peak heights and peak height ratios (PHR) from the STR profiles were examined to assess profile quality of samples extracted using the Trypsin-ZyGEM protocol and the Qiagen protocol. Peak heights and peak height ratios (PHR) were found to be consistent between the two methods. / 2017-11-03T00:00:00Z

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