The Human ARF Tumor Suppressor Regulates Drosha Nucleolar Localization and rRNA Processing Activity

Ribosomes are vital to the survival of a cell, as they are directly responsible for the synthesis of proteins, which perform critical cellular functions. As such, majority of the energy reserves in a proliferating cell are expended towards synthesis of ribosomes. Cancer cells, with their enhanced proliferation rates, tend to upregulate ribosome biogenesis in order to meet the demand for increased protein synthesis necessary to sustain rapid proliferation. Many of the oncogenes and tumor suppressors known to be deregulated in cancers are capable of positively and negatively regulating ribosome biogenesis, respectively. The ARF tumor suppressor strongly suppresses ribosome biogenesis, particularly in presence of oncogenic signaling. Furthermore, ARF is capable of negatively regulating multiple oncogenes capable of driving tumorigenesis partly through the ribosome biogenesis pathway. As ARF loss is a frequent occurrence in cancer cells, delineating the ARF-regulatory network and determining the impact of ARF loss on this network can give significant insight into the biology of ARF-deficient tumor cells. Expression of the RNase III enzyme, Drosha, has been reported to have prognostic value in multiple cancers. However, Drosha expression appears to have a dual nature in tumorigenesis, as both overexpression and loss of Drosha have been reported to have tumorigenic functions. Although the mechanistic basis of this apparent duality are not yet known, gaining a deeper understanding of Drosha\u27s functional capabilities can give us an insight into its role in tumorigenesis. Drosha performs critical functions in biogenesis of multiple RNA species within the cell, including ribosomal RNA (rRNA), micro RNA (miRNA) and messenger RNA (mRNA). Drosha\u27s role in miRNA biogenesis is the most studied and characterized aspect of its functions and can explain the tumor suppressive aspect of its dual nature; a global decrease in miRNAs has been reported to be part of tumor progression, and loss of Drosha has the potential to significantly deplete mature miRNA population within the cell. However, how overexpression of Drosha can drive tumorigenesis remains to be studied. As enhanced ribosome biogenesis is another feature of cancer cells and Drosha has been shown to aid in processing of r RNA, Drosha\u27s role in ribosome biogenesis pathway has the potential to function in an oncogenic manner. Therefore, further characterization of Drosha\u27s role in ribosome biogenesis can significantly enhance our understanding of its contribution to tumorigenesis. Recent studies in mouse cell lines revealed that ARF tumor suppressor is capable of negatively regulating Drosha expression in a translation-dependent manner. Given the entrenched role of ARF in inhibiting ribosome biogenesis, I hypothesized that ARF\u27s ability to regulate Drosha could impact Drosha\u27s functions in ribosome biogenesis pathway. I further hypothesized that Drosha overexpression could function in a pro-proliferative manner through the ribosome biogenesis pathway. The data presented in this Dissertation reveals that human p14ARF is capable of regulating Drosha protein expression in a dynamic and localized fashion; loss of ARF increases over all cellular Drosha protein levels and also the localization of Drosha to the nucleolus. ARF potentially regulates nucleolar localization of Drosha by sequestering it away from nucleolus, as we found that ARF immunoprecipitated with Drosha in RNA-independent manner. Furthermore, loss of ARF enhances ribosome biogenesis both at the level of 47s rRNA transcription and processing. Association of Drosha with precursor rRNAs was also enhanced in absence of ARF, suggesting that enhanced nucleolar localization of Drosha upon ARF loss contributes to rRNA processing. Drosha overexpression by itself was able to increase ribosome biogenesis, with a modest increase in 47s rRNA transcription and a faster accumulation of 28s and 18s rRNAs. Drosha overexpression led to an increase in ARF expression, although this induction of ARF was not sufficient to inhibit Drosha\u27s ability to enhance ribosome biogenesis and cell proliferation. However, overexpression of ARF negated proliferative enhancement induced by Drosha overexpression. These results point towards a cross-regulatory loop between ARF and Drosha, with functional impact on ribosome biogenesis

Master of Science

thesisAn increase in the demand for clean and sustainable energy storage with a high power density, along with a long cyclic life time has made supercapacitors an emerging energy storage device. However, one of the main challenges of today's world is to develop energy storage devices which are environmental friendly, cost effective, and which posses an excellent storage capacity. Therefore, this thesis presents the experimental results of utilizing nickel nanoparticle impregnated carbonized wood as a potential electrode material for supercapacitor applications. The electrode was synthesized by carbonizing the nickel nitrate impregnated wood at 900oC for an hour. The concentration of nickel nanoparticles in the carbonized wood was varied by changing the concentration of nickel nitrate solution. The surface morphology and the structure of the electrodes as prepared were studied by using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and X-ray Photoelectron Spectroscopy (XPS). Electrochemical characterization such as Cyclic Voltammetry showed the presence of peaks indicating a psuedocapacitive behavior of the electrode. The Galvanostatic charge-discharge measurements showed nonlinear charge-discharge curves with changes in the slope. From the electrochemical measurements, it is observed that the electrode material exhibited a specific capacitance of 3616 F/g and a power density of 30 kW/kg along with an excellent capacitance retention of greater than 80% after 6000 charge-discharge cycles. These results indicate that the nickel nanoparticle impregnated carbonized wood could be one of the potential electrode materials for supercapacitor applications

Financial Analysis of Meta Platforms Inc

Web3.0 is the latest generation of internet, which is about decentralization and democratization, built on blockchain technology, high computer power and high-speed network. Metaverse overlaps with Web3.0 in terms of decentralization and is built on the same base technologies but talks about virtual realities and brings immersive experiences. This study explores how the web has evolved over the years and analyzes the current market trends of Web3.0. The purpose of the study is to examine the investments made by Meta Platforms Inc. which is one of the market leaders of the Internet industry and provide an in-depth financial analysis by evaluating its financial statements and different financial metrics. The study also includes estimating the value of the company based on the Discounted Cash Flow valuation method. The valuation conducted in this study forecasts Meta Platforms Inc. to be a promising investment with high positive returns. The valuation may be utilized by analysts for further analysis in their research

The Soy-Derived Peptide Lunasin Inhibits Invasive Potential of Melanoma Initiating Cells

Lunasin is a 44 amino acid peptide with multiple functional domains including an aspartic acid tail, an RGD domain, and a chromatin-binding helical domain. We recently showed that Lunasin induced a phenotype switch of cancer initiating cells (CIC) out of the stem compartment by inducing melanocyte-associated differentiation markers while simultaneously reducing stem-cell-associated transcription factors. In the present study, we advance the hypothesis that Lunasin can reduce pools of melanoma cells with stem cell-like properties, and demonstrate that Lunasin treatment effectively inhibits the invasive potential of CICs in vitro as well as in vivo in a mouse experimental metastasis model. Mice receiving Lunasin treatment had significantly reduced pulmonary colonization after injection of highly metastatic B16-F10 melanoma cells compared to mice in the control group. Mechanistic studies demonstrate that Lunasin reduced activating phosphorylations of the intracellular kinases FAK and AKT as well as reduced histone acetylation of lysine residues in H3 and H4 histones. Using peptides with mutated activity domains, we functionally demonstrated that the RGD domain is necessary for Lunasin uptake and its ability to inhibit oncosphere formation by CICs, thus confirming that Lunasin’s ability to affect CICs is at least in part due to the suppression of integrin signaling. Our studies suggest that Lunasin represents a unique anticancer agent that could be developed to help prevent metastasis and patient relapse by reducing the activity of CICs which are known to be resistant to current chemotherapies

A murine model for neuropsychiatric disorders associated with group A β-hemolytic streptococcal infection

A syndrome of motoric and neuropsychiatric symptoms comprising various elements, including chorea, hyperactivity, tics, emotional lability, and obsessive-compulsive symptoms, can occur in association with group A β-hemolytic streptococcal (GABHS) infection. We tested the hypothesis that an immune response to GABHS can result in behavioral abnormalities. Female SJL/J mice were immunized and boosted with a GABHS homogenate in Freund's adjuvant, whereas controls received Freund's adjuvant alone. When sera from GABHS-immunized mice were tested for immunoreactivity to mouse brain, a subset was found to be immunoreactive to several brain regions, including deep cerebellar nuclei (DCN), globus pallidus, and thalamus. GABHS-immunized mice having serum immunoreactivity to DCN also had increased IgG deposits in DCN and exhibited increased rearing behavior in open-field and hole-board tests compared with controls and with GABHS-immunized mice lacking serum anti-DCN antibodies. Rearing and ambulatory behavior were correlated with IgG deposits in the DCN and with serum immunoreactivity to GABHS proteins in Western blot. In addition, serum from a GABHS mouse reacted with normal mouse cerebellum in nondenaturing Western blots and immunoprecipitated C4 complement protein and α-2-macroglobulin. These results are consistent with the hypothesis that immune response to GABHS can result in motoric and behavioral disturbances and suggest that anti-GABHS antibodies cross-reactive with brain components may play a role in their pathophysiology

Toll-like Receptor 3 Regulates Neural Stem Cell Proliferation by Modulating the Sonic Hedgehog Pathway

Toll-like receptor 3 (TLR3) signaling has been implicated in neural stem/precursor cell (NPC) proliferation. However, the molecular mechanisms involved, and their relationship to classical TLR-mediated innate immune pathways, remain unknown. Here, we report investigation of the mechanics of TLR3 signaling in neurospheres comprised of epidermal growth factor (EGF)-responsive NPC isolated from murine embryonic cerebral cortex of C57BL/6 (WT) or TLR3 deficient (TLR3−/−) mice. Our data indicate that the TLR3 ligand polyinosinic-polycytidylic acid (PIC) negatively regulates NPC proliferation by inhibiting Sonic Hedgehog (Shh) signaling, that PIC induces apoptosis in association with inhibition of Ras-ERK signaling and elevated expression of Fas, and that these effects are TLR3-dependent, suggesting convergent signaling between the Shh and TLR3 pathways

Differences in 53BP1 and BRCA1 regulation between cycling and non-cycling cells

BRCA1 and 53BP1 play decisive roles in the choice of DNA double-strand break repair mechanisms. BRCA1 promotes DNA end resection and homologous recombination (HR) during S/G(2) phases of the cell cycle, while 53BP1 inhibits end resection and facilitates non-homologous end-joining (NHEJ), primarily during G(1). This competitive relationship is critical for genome integrity during cell division. However, their relationship in the many cells in our body that are not cycling is unknown. We discovered profound differences in 53BP1 and BRCA1 regulation between cycling and non-cycling cells. Cellular growth arrest results in transcriptional downregulation of BRCA1 and activation of cathepsin-L (CTSL)-mediated degradation of 53BP1. Accordingly, growth-arrested cells do not form BRCA1 or 53BP1 ionizing radiation-induced foci (IRIF). Interestingly, cell cycle re-entry reverts this scenario, with upregulation of BRCA1, downregulation of CTSL, stabilization of 53BP1, and 53BP1 IRIF formation throughout the cycle, indicating that BRCA1 and 53BP1 are important in replicating cells and dispensable in non-cycling cells. We show that CTSL-mediated degradation of 53BP1, previously associated with aggressive breast cancers, is an endogenous mechanism of non-cycling cells to balance NHEJ (53BP1) and HR (BRCA1). Breast cancer cells exploit this mechanism to ensure genome stability and viability, providing an opportunity for targeted therapy