Ribonucleoprotein complexes (RNPs) are involved in many essential cellular processes, of which the most prominent examples include the ribosome that functions in protein translation and the spliceosome which catalyzes pre-mRNA splicing. The biogenesis of RNPs often involves complex and elaborate pathways involving post-translational modifications, transit into specific cellular domains, and several auxiliary factors including assembly chaperones. One of the best-studied examples of such a chaperone is the survival motor neuron (SMN) protein, the disease gene in spinal muscular atrophy (SMA). SMN is part of a macromolecular protein complex and catalyzes the assembly of a heptameric core of Sm proteins onto small nuclear RNAs (snRNAs) to form spliceosomal snRNPs required for RNA splicing. The Sm and Sm-like (LSm) proteins are an evolutionarily conserved family of proteins that exhibit the propensity to form diverse heteromeric complexes with unique RNA-binding characteristics. The Sm/LSm proteins are thought to function as RNA chaperones whose association with their target RNAs plays a critical role in the maturation, transport, and stability of the resulting RNPs as well as modulation of RNA-RNA and RNA-protein interactions that are critical for RNP function. Sm/LSm containing RNPs have been shown to function in a variety of cellular pathways in addition to pre-mRNA splicing, including histone mRNA 3' end formation and mRNA decay. Interestingly, in addition to its direct binding to Sm proteins, SMN has been shown to associate in vitro with members of the LSm family as well as other RNA binding proteins, implicating the SMN complex in the biology of other cellular RNPs. The discovery of the full spectrum of RNPs that are dependent on SMN activity has important implications not only for our understanding of fundamental aspects of post-transcriptional gene regulation but also for SMA pathogenesis. To pursue this line of investigation, in this dissertation, I explore the hypothesis that SMN plays a general role in RNP assembly that extends to novel RNAs that function in diverse cellular pathways. First, I report the identification of a RNA polymerase III transcript of unknown function to be a novel cell type-specific RNA target of SMN function in ribonucleoprotein assembly. Second, I explore the role of SMN in the biology of the nuclear LSm2-8 complex active in splicing and the cytoplasmic LSm1-7 complex involved in mRNA decay. Finally, to facilitate the discovery of cellular pathways linked to SMN biology, I describe a novel cell-based model system for the phenotypic screening of genetic and pharmacological modifiers of SMN expression and function. Together, my studies significantly expand the repertoire of cellular RNAs that SMN is known to target and provide a unique platform for the identification of novel SMN-dependent cellular pathways, which have relevance for understanding RNA regulation and disease mechanisms and may help in the development of therapeutic approaches to SMA.

RNA polymerase II (RNAP II), transcribing messenger RNAs (mRNAs), small nuclear RNAs (snRNAs), and non-coding RNAs (ncRNAs), is composed of 12 subunits. Rpb1, the largest subunit with catalytic polymerase activity, possesses a unique c-terminal domain (CTD) that consists of tandem heptad repeats with the consensus sequence of Tyr-Ser-Pro-Thr-Ser-Pro-Ser (Y1S2P3T4S5P6S7). Somewhat reflecting the complexity of the organism, the number of repeats varies, from 26 in yeast to 52 in vertebrates. The CTD, intensively phosphorylated during transcription, serves a means to coordinate transcription and RNA processing- capping, splicing, and 3' end formation. For example, Ser 5, phosphorylated in the start of transcription, promotes the recruitment of capping enzyme, and Ser 2 phosphorylation facilitates RNA 3' end formation and transcription termination by acting as a landing pad for Pcf11. Detailed introduction is described in Chapter 1. Because of the importance of the CTD in these events, I created an Rpb1 conditional knock-out DT40 cell line (DT40-Rpb1) to further study the CTD with an initial focus on Thr 4, the function of which was unclear. Using DT40-Rpb1 system, we found that Thr 4 was phosphorylated in yeast, fly, chicken, and human cells, and cyclin-dependent kinase (CDK9) was likely the kinase to carry out this phosphorylation. We further provide evidence that Thr 4 functions in histone mRNA 3' end formation (presented mostly in chapter 2 of this thesis). Chapter 3 mainly describes the studies regarding Ser 2, Ser 5, and Ser 7. Based on the DT40-Rpb1 cell line, I created stable cell lines expressing an Rpb1 carrying a CTD with Ser 2, Ser 5, or Ser 7 mutated to alanine, and investigated the phenotypes of these cells. We found that cells expressing an Rpb1 with S2A or S5A mutation were defective in transcription and RNA processing. Contrary to previous findings, we found Ser 7 was not involved in snRNA expression and 3' end processing. In fact, no phenotypes associated with Ser 7 mutation were detected by our measurements. Extending previous Thr 4 studies, we showed in vitro and in vivo that Fcp1 dephosphorylated Thr 4. Finally, Chapter 4 describes what we have found the functions of CTD Tyr 1. Using the DT40-Rpb1 cells, I created stable cell lines expressing an Rpb1 with all Tyr residues mutated to phenylalanine (Phe). We found these cells were inviable, and the mutant Rpb1-Y1F was degraded to a CTD-less protein. Interestingly, the instability of Rpb1-Y1F was restored by reintroduction of one Tyr residue at the last heptad repeat. Further analysis provided evidence showing the involvement of Tyr phosphorylation in preventing Rpb1 from degradation by the 20S proteasome. Next, using ChIP assay, we showed Tyr phosphorylation was detected mostly at promoters, indicating a function of Tyr phosphorylation in transcription initiation. Indeed, transcription initiation defects were uncovered by assessing the recruitment of general transcription factors in cells with Y1F mutation. Extending this, we found an accumulation of upstream antisense RNAs in about one hundred reference genes by RNA-Seq analysis.

Cell motility is an essential process that depends on a coherent, cross-linked cytoskeleton that physically coordinates the actions of numerous structural and signaling molecules. In culture, a common feature of cells is the coherent movement of the endoplasmic reticulum and membranous organelles toward the periphery during substrate adhesion and spreading. The actin cross-linking protein, filamin (Fln), has been implicated in the support of three-dimensional cortical actin networks capable of both maintaining cellular integrity and withstanding large forces. Although numerous studies have examined cells lacking one of the multiple Fln isoforms, compensatory mechanisms can mask novel phenotypes only observable by further Fln depletion. Indeed, shRNA-mediated knockdown of FlnA in FlnB-/- mouse embryonic fibroblasts (MEFs) causes a novel endoplasmic spreading deficiency as detected by endoplasmic reticulum markers. Microtubule (MT) extension rates are also decreased but not by peripheral actin flow, because this is also decreased in the Fln-depleted system. Additionally, Fln-depleted MEFs exhibit decreased adhesion stability that leads to increased ruffling of the cell edge, reduced adhesion size, transient traction forces, and decreased stress fibers. FlnA-/- MEFs, but not FlnB-/- MEFs, also show a moderate defect in endoplasm spreading, characterized by initial extension followed by abrupt retractions and stress fiber fracture. FlnA localizes to actin linkages surrounding the endoplasm, adhesions, and stress fibers. Thus I suggest that Flns have a major role in the maintenance of actin-based mechanical linkages that enable endoplasmic spreading and MT extension as well as sustained traction forces and mature focal adhesions. I also report that treatment with the calpain inhibitor N-[N-(N-Acetyl-L-leucyl)-L-leucyl]- L-norleucine (ALLN) restores endoplasmic spreading and focal adhesion (FA) maturation in the absence of Fln. Further, expression of calpain-uncleavable talin, but not full-length talin, also rescues endoplasmic spreading in Fln-depleted cells and indicates a crucial role for stable, mature FAs in endoplasmic spreading. Because FA maturation involves the vimentin intermediate filament (vIF) network, I also examined the role of vIFs in endoplasmic spreading. Wild-type cells expressing a dominant-negative vimentin variant incapable of vIF polymerization exhibit deficient endoplasmic spreading as well as defects in FA maturation. ALLN treatment restores FA maturation despite the lack of vIFs, but does not restore endoplasmic spreading. Consistent with a role for vIFs in endoplasmic spreading, adhesive structures do not contain vIFs when the endoplasm does not spread. Fln-depleted cells also exhibit a microtubule-dependent mistargeting of vIFs. Thus, I propose a model in which cellular force generation and interaction of vIFs with mature FAs are required for endoplasmic spreading. Additionally, I discuss future lines of investigation concerning the role of FlnA in the endoplasmic spreading mechanism as well as mechanosensitive functions of FlnA. Finally, I speculate on a potential application of endoplasmic spreading deficiencies as hallmarks of metastatic breast cancer.

The work of my thesis is the cumulative result of 6 years of research in Prof. Michael P. Sheetz laboratory at the Biological Sciences Department of Columbia University, within the collaborative framework of the Nanotechnology Center for Mechanobiology, an interdisciplinary and multi-institutional center for the study of cell mechanics, involving, among other institutions, the Applied Physics department at Columbia University, and the Schools of Medicine of University of Pennsylvania, New York University, and Mt Sinai. In Chapter 1, I provide an overview of the field of mechanobiology, with an emphasis on the implications of cell-extracellular matrix and cell-cell attachment on cell function. In Chapter 2, I present the aims of the thesis, with a focus on the two cell systems used in the projects described: human mesenchymal stem cells, and T cells. Then, Chapters 3-5 represent the main body of my thesis, where I present detailed descriptions of the projects that I worked on and that successfully made it into scientific publications or that are in preparation for publication. In Chapter 3, I analyze how matrix chemistry and substrate rigidity affect human mesenchymal stem cell morphology in the context of lineage differentiation, and speculate on potential mechanisms that cells use to sense local rigidity. In Chapter 4, I present a new substrate design that facilitates live visualization of the interface formed between a T cell and an antigen presenting cell, i.e. the immunological synapse, and discuss the impact of intercellular forces on T cell activation. In Chapter 5, I explore the molecular mechanism of Cas-L mechanical activation at the immunological synapse of T cells, and demonstrate how Cas-L regulates T cell activation in the context of an immune response. Finally, in Chapter 6, I lay down the main conclusions of the thesis, and discuss ongoing projects that directly follow up on the results of this thesis.

It is well established that the p53 tumor suppressor plays a crucial role in controlling cell proliferation and apoptosis upon various types of stress. There is increasing evidence showing that p53 is also critically involved in various non-canonical pathways, including metabolism, autophagy, senescence and aging. Through a ChIP-on-chip screen, we identified a novel p53 metabolic target, pantothenate kinase-1 (PANK1). PanK1 catalyzes the rate-limiting step for CoA synthesis, and therefore, controls intracellular CoA content; Pank1 knockout mice exhibit defect in β-oxidation and gluconeogenesis in the liver after starvation due to insufficient CoA levels. We demonstrated that PANK1 gene is a direct transcriptional target of p53. Although DNA damage-induced p53 upregulates PanK1 expression, depletion of PanK1 expression does not affect p53-dependent growth arrest or apoptosis. Interestingly, upon glucose starvation, PanK1 expression is significantly reduced in HCT116 p53 (-/-) but not in HCT116 p53 (+/+) cells, suggesting that p53 is required to maintain PanK1 expression under metabolic stress conditions. Moreover, by using p53-mutant mice, we observed that PanK activity and CoA levels are lower in livers of p53-null mice than that of wild-type mice upon starvation. Similar to the case in Pank1 knockout mice, β-oxidation and gluconeogenesis are impaired in p53-null mice. Together, our findings show that p53 is critical in regulating energy homeostasis through transcriptional control of PANK1. Our study on PANK1 led us to the question of how p53 can differentially regulate a diverse array of downstream targets in a context-dependent manner. Studies have shown that p53 acetylation at K120 and K164 lysine residues contribute to p53-mediated apoptosis and growth arrest functions, which was further supported by the 3KR mouse model (K117/161/162R) that mirrors the K120/164R mutations in human p53. These studies also suggest that a potentially large number of p53 targets can still be regulated by p53 in the absence of K120/164 acetylation (K117/161/162R in mouse). To investigate whether additional modifications of p53 can further contribute to promoter-specific transactivation, we conducted a screen using mass spectrometry and identified a novel acetylation site at K101. Our data demonstrated that K101 in human p53, as well as the homologous K98 lysine residue in mouse p53, can be acetylated by acetyltransferase CBP. Acetylation at this novel site does not contribute to p53 stability or DNA-binding capabilities. Ablation of K98 acetylation in mouse p53 alone does not affect the transcriptional activity of p53. However, simultaneous loss of K98 acetylation with the previously characterized K117/161/162 acetylations (4KR98 p53) significantly abrogates p53-mediated activation of TIGAR and MDM2 genes. The 3KR mouse model, although cannot elicit canonical p53-mediated apoptotic and cell cycle arrest responses, still retains the ability to suppress tumor formation. We, therefore, investigated whether other non-canonical targets of p53 could potentially mediate tumor suppression. By RNA-seq profiling of gene expression in cells expressing 3KR p53, we identified TNFRSF14 (tumor necrosis factor receptor superfamily, member 14) as a novel p53 target. The TNFRSF14 receptor has been shown to be frequently mutated in follicular lymphoma and diffuse large B cell lymphoma, and stimulation by its ligand LIGHT leads to cell death in many cancer cells. We report that TNFRSF14 is a novel p53 target that can be activated by 3KR p53. Interestingly, transactivation of TNFRSF14 is defective by 4KR98 p53. Furthermore, LIGHT ligand stimulates cell death in TNFRSF14-expressing cells and cells expressing 3KR p53, but not those expressing 4KR98 p53. Altogether, our findings in these studies underscore the extensive scope of p53 functions and provide new insights into the versatility of non-canonical pathways. Not only does p53 mediate tumor suppression through both canonical and non-canonical downstream effectors, p53 can also contribute to cellular homeostasis and energy balance.

Mechanosensation underlies multiple senses, such as touch, pain, hearing, and proprioception. The molecules that mediate most of the mechanical senses have not been identified. Genetic and molecular methods have identified several putative mechanosensitive proteins. However, how the mechanotransduction machineries organize and function remains largely unknown. To understand the organization of the mechanotransduction complex, I studied the DEG/ENaC mechanosensory channel that detects gentle touch in the six touch receptor neurons (TRNs) of C. elegans. Previous studies from our lab have suggested that this channel complex contains two pore-forming subunits MEC-4 and MEC-10 (DEG/ENaC proteins) and two auxiliary subunits MEC-6 (paraoxonase-like protein) and MEC-2 (stomatin-like protein). However, questions remain about what molecules really constitute this mechanosensory channel complex. Studying this particular DEG/ENaC channel in C. elegans will not only elucidate the organization of one major mechanosensory complex, but also improve our knowledge of other DEG/ENaC proteins, which are found in both vertebrates and invertebrates, and involved in various functions, e.g. mechanosensation, sodium taste, acid sensation, synaptic plasticity, and sodium homeostasis. My thesis research investigated the molecular organization and formation of the DEG/ENaC mechanosensory channel in C. elegans. In collaboration with Ehud Isacoff's lab, I analyzed the stoichiometry and co-localization of the potential channel subunits using single molecule optical imaging. In Xenopus oocytes, MEC-4 and MEC-10 form trimers, either of MEC-4 alone or of MEC-4 and MEC-10 in a ratio of 2:1. MEC-2 and MEC-6 do not seem to colocalize with the MEC-43 or MEC-42MEC-10 trimers at the single molecule level, and thus, may not be part of the channel complex. To study the role of MEC-6, I characterized its homologous protein POML-1. Compared to MEC-6, POML-1 appears to play a similar but relatively minor role in the TRNs. As with mec-6, loss of poml-1, completely suppressed mec-4(d) induced neuronal degeneration. [mec-4(d) encodes a hyperactive channel and causes neuronal degeneration in vivo]. Loss of poml-1 alone had no effect, but in sensitized background, it completely abolished touch sensitivity. Surprisingly, most of MEC-6 and POML-1 proteins were found in the endoplasmic reticulum (ER), rather than on the plasma membrane, consistent with the finding in Xenopus oocytes that MEC-6 is not part of the MEC-4 mechanosensory channel. I provided several lines of compelling evidence to demonstrate that MEC-6 and POML-1 are required for MEC-4 folding and transport, and likely function as ER chaperones. First, loss of these proteins dramatically reduced MEC-4 protein level, eliminated the punctate distribution of MEC-4 in the neuronal process, and altered the MEC-4 folding status in the TRNs. These phenotypes are also shared by calreticulin (CRT-1), a chaperone in the ER. Second, MEC-6 also substantially increased MEC-4 surface expression in Xenopus oocytes, though POML-1 and CRT-1 did not have the same effect in oocytes. Third, overexpressing a transport protein, SEC-24, partially rescued the transport defects caused the poml-1 and crt-1 mutations. Based on the finding that loss of poml-1 reduces MEC-4 protein levels and suppresses neurodegeneration caused by the hyperactive MEC-4(d) channel, I used the poml-1 deletion as a sensitized background to identify genes that normally inhibit MEC-4(d) neurotoxicity through a genetic screen. I found that the loss of two genes, mec-10 and C49G9.1, makes mec-4(d) more toxic. The proteins encoded by these genes affect mec-4(d) neurotoxicity through different mechanisms. MEC-10 inhibits MEC-4(d) without affecting MEC-4 surface expression. In contrast, both in vivo and in vitro data suggested that C49G9.1, a membrane protein specific to nematodes, can reduce MEC-4 surface expression, which contributes to, at least in part, its inhibitory effect on MEC-4(d). C49G9.1 does not incorporate into the MEC-4/MEC-10 channel, though they may transiently interact, because C49G9.1 did not appear to co-localize with MEC-4 either in vivo or in vitro, but co-immunoprecipitated with MEC-4. In summary, my doctoral research has refined the model of the MEC-4/MEC-10 complex. In particular, my studies resolved the subunits composition of DEG/ENaC channel at the single molecule level, by showing that they form MEC-42MEC-10 trimers in Xenopus oocytes. Notably, MEC-2 and MEC-6 may not be part of the complex. Indeed, I provided compelling evidence to demonstrate that MEC-6 and POML-1 are needed for MEC-4 folding and transport, and likely function as chaperones and/or assembly factors. In addition, I identified a novel membrane protein, C49G9.1, which negatively regulates MEC-4 surface expression and/or activities. This work has revised our understanding of a major mechanosensory complex and described a new class of chaperone proteins as well as a new inhibitor protein for DEG/ENaC proteins.

We investigated the role of Notch signaling in the vascular microenvironment, with particular attention paid to the vascular consequences of Notch signaling disruption in myeloid cells. We adapted an established in vitro model of angiogenesis to recreate interactions between endothelial sprouts and vascular support cells, including macrophages and vascular pericytes. We found that inflammatory polarization of macrophages increased their ability to foster angiogenesis, and that intact Notch signaling was essential to this phenomenon. We also demonstrated a role for Notch/Jagged1 signaling in the interaction between vascular pericytes and endothelial sprouts, the disruption of which limits the growth and maturation of vessel networks. We have also investigated the role of myeloid Notch signaling in vivo, using a number of developmental and pathological models of angiogenesis. We found that Notch inhibition leads to decreased myeloid cell recruitment to a broad variety of functionally distinct angiogenic sites. Importantly, we observed that myeloid Notch disruption has vascular consequences in both physiological and pathological angiogenesis. Myeloid Notch- inhibited mice exhibit decreased vascular complexity in the deep retinal plexus during development. Additionally, these mice show significantly increased vascular tuft formation in the setting of oxygen-induced retinopathy, suggestive of a heretofore- undescribed role for myeloid Notch signaling in the pathogenesis of this significant human disease. This body of work increases our understanding of the role of Notch signaling both in the dynamics of myeloid cells and in their specific contribution to angiogenesis in multiple disparate contexts. It also contributes to our understanding of a number of key models of human disease, and may prove useful in the development of novel therapies to treat those diseases. Further, we are confident that our new experimental methodology will allow continued fruitful reductive study of the complex intercellular interactions within the vascular microenvironment.

Cytoplasmic dynein 1 is crucial for many cellular processes including endocytosis and cell division. Dynein malfunction can lead to neurodevelopmental and neurodegenerative disease, such as intellectual disability, Charcot-Marie-Tooth disease and spinal muscular atrophy with lower extremity predominance. We formulate, based on physical principles, a mechanical model to describe the stepping behaviour of cytoplasmic dynein walking on microtubules. Unlike previous studies on physical models of this nature, we base our formulation on the whole structure of dynein to include the temporal dynamics of the individual components such as the cargo (for example an endosome or bead), two rings of six ATPase domains associated with diverse cellular activities and the microtubule binding domains. This mathematical framework allows us to examine experimental observations across different species of dynein as well as being able to make predictions (not currently experimentally measured) on the temporal behaviour of the individual components of dynein. Initially, we examine a continuous model using plausible force functions to model the ATP force and binding affinity to the microtubule. Our results show hand-over-hand and shuffling stepping patterns in agreement with experimental observations. We are able to move from a hand-overhand to a shuffling stepping pattern by changing a single parameter. We also explore the effects of multiple motors. Next, we explore stochasticity within the model, modelling the binding of ATP as a random event. Our results reflect experimental observations that dynein walks using a predominantly shuffling stepping pattern. Furthermore, we study the effects of mutated dynein and extend the model to include variable step sizes, backward stepping and dwelling. Independent stepping is studied and the results show that coordinated stepping is needed in order to obtain experimental run lengths.

Aminoglycoside antibiotics are a class of drug used to treat bacterial infections but have the unfortunate side effect of being both oto- and nephro-toxic. Deafness caused by aminoglycoside ototoxicity results from a loss of sensory hair cells from the inner ear. In vitro, two early effects of aminoglycoside exposure can be observed. First, membrane blebs are formed around the perimeter of the hair-cell apical surface. Secondly phosphatidylserine (PS), an aminophospholipid that is normally restricted to the inner leaflet of the plasma membrane, flops to the outer leaflet. This membrane damage occurs rapidly, within 90-120 seconds of drug exposure and can be completely reversed. The aim of this thesis was to determine the molecular mechanisms underlying damage repair in sensory hair cells recovering from aminoglycoside damage. TEM studies using cationic ferritin as a tracer indicates the repair process involves membrane internalisation, but recovery cannot be blocked by inhibitors of macropinocytosis, the clathrin-independent carrier (CLIC) pathway, PI3 kinase, PKC, Pak1 or of the clathrin-coated pit pathway. Damage repair is, however, prevented by the actin stabiliser jasplakinolide and the inhibitor of Protein kinase A, H-89. In addition, the CLIC pathway inhibitor EIPA has been uncovered as a reversible blocker of aminoglycoside entry into hair cells.

Siu, Yeung Tung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 65-75). / Abstracts in English and Chinese. / Title Page --- p.i / Abstract in English --- p.ii / Abstract in Chinese --- p.iii / Acknowledgement --- p.iv / Table of Contents --- p.v-viii / List of Figures --- p.ix / List of Tables --- p.x / Abbreviations --- p.xi-xii / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Growth factors involved in hepatocytes proliferation --- p.1-6 / Chapter 1.1.1 --- Hepatocyte growth factor (HGF) --- p.1 / Chapter 1.1.2 --- Tumor necrosis factor-a (TNF-α) and interleukin-6 (IL-6) --- p.2 / Chapter 1.1.3 --- Epidermal growth factor (EGF) and transforming growth factor-α (TGF-α) --- p.3 / Chapter 1.1.4 --- Other comitogens --- p.4 / Chapter 1.1.5 --- Transforming growth factor-β (TGF-β) --- p.5 / Chapter 1.2 --- Bone marrow stromal cells and hepatocytes proliferation --- p.7-12 / Chapter 1.2.1 --- Role of bone marrow stromal cells in bone marrow --- p.7 / Chapter 1.2.2 --- Bone marrow as a source of hepatic oval cells --- p.8 / Chapter 1.2.3 --- Growth factors secreted by bone marrow stromal cells involved in hepatocytes proliferation --- p.9 / Chapter 1.2.4 --- Endocrine in hepatocytes proliferation --- p.12 / Chapter 1.3 --- Objective of this study --- p.13-15 / Chapter Chapter 2 --- Materials and Methods / Chapter 2.1 --- Cell cultures --- p.16 / Chapter 2.2 --- Selection of human hepatic cell line for the detection of mitogenic activity --- p.17-18 / Chapter 2.2.1 --- "Enrichment of human hepatic cell lines, Hep 3B, Hep G2, C3A, SK-Hep-1 and Chang cells at G0-G1 phases by serum deprivation" --- p.17 / Chapter 2.2.2 --- "Incubation of serum deprived Hep 3B, Hep G2, C3A, SK- Hep-1 and Chang cells with mitogenic stimuli" --- p.17 / Chapter 2.2.3 --- Cell cycle analysis by flow cytometry using propidium iodide staining --- p.17 / Chapter 2.3 --- "Detection of mitogenic activity of human bone marrow stromal cells on the selected cell line, SK-Hep-1 cells" --- p.18-20 / Chapter 2.3.1 --- Partially growth arrested human SK-Hep-1 cells --- p.18 / Chapter 2.3.2 --- Human bone marrow stromal cells --- p.19 / Chapter 2.3.2.1 --- Bone marrow stromal cellular extract --- p.19 / Chapter 2.3.2.2 --- Total protein assay --- p.19 / Chapter 2.3.3 --- Incubation of SK-Hep-1 cells with bone marrow stromal cellular extracts --- p.20 / Chapter 2.4 --- Characterization of hepatocyte mitogenic activity of bone marrow stromal cellular extract --- p.21-22 / Chapter 2.4.1 --- Dialysis --- p.21 / Chapter 2.4.2 --- Temperature treatment --- p.21 / Chapter 2.4.3 --- Proteolysis --- p.22 / Chapter 2.5 --- Performing a preliminary test on the difference between bone marrow stromal cellular extract and other growth factors --- p.22-26 / Chapter 2.5.1 --- Incubation of SK-Hep-1 cells with bone marrow stromal cellular extract or other growth factors --- p.22 / Chapter 2.5.2 --- Metabolic labeling of SK-Hep-1 cells with [32P]orthophosphate --- p.23 / Chapter 2.5.3 --- Incubation of labeled SK-Hep-1 cells with bone marrow stromal cellular extract or other growth factors --- p.23 / Chapter 2.5.4 --- SK-Hep-1 cells lysate extraction --- p.23 / Chapter 2.5.5 --- Two-dimensional electrophoresis --- p.24 / Chapter 2.5.5.1 --- First dimension isoelectric focusing --- p.24 / Chapter 2.5.5.2 --- Second dimension sodium dodecyl sulfate-polyacrylamide gel electrophoresis --- p.25 / Chapter 2.5.6 --- Amplification of radiolabeled signal by EN3HANCE --- p.25 / Chapter 2.5.7 --- Visualization of autoradiography --- p.26 / Chapter 2.5.8 --- Visualization by silver staining --- p.26 / Chapter Chapter 3 --- Results / Chapter 3.1 --- Selection of human hepatic cell line for the detection of mitogenic activity --- p.27-30 / Chapter 3.1.1 --- "Enrichment of human hepatic cell lines, Hep 3B, Hep G2, C3A, SK-Hep-1 and Chang cells at G0-G1 phases by serum deprivation" --- p.27 / Chapter 3.1.2 --- DNA synthesis of hepatic cell lines in response to 10 % FBS after serum deprivation --- p.29 / Chapter 3.2 --- "Detection of mitogenic activity of human bone marrow stromal cells on the selected cell line, SK-Hep-1 cells" --- p.31-39 / Chapter 3.2.1 --- Cell cycle distribution of partially growth arrested SK-Hep-1 cells in response to mitogens --- p.31 / Chapter 3.2.2 --- Time course on DNA synthesis of partially growth arrested SK-Hep-1 cells in response to FBS and bone marrow stromal cellular extract --- p.36 / Chapter 3.2.3 --- Dose response on DNA synthesis of partially growth arrested SK-Hep-1 cells in response to bone marrow stromal cellular extracts --- p.38 / Chapter 3.3 --- Characterization of hepatocyte mitogenic activity of bone marrow stromal cellular extract --- p.40-44 / Chapter 3.4 --- Performing a preliminary test on the difference between bone marrow stromal cellular extract and other growth factors --- p.45-49 / Chapter 3.4.1 --- Mitogenic response of SK-Hep-1 cells in response to bone marrow stromal cellular extract and other growth factors --- p.45 / Chapter 3.4.2 --- Early intracellular signaling of SK-Hep-1 cells in response to bone marrow stromal cellular extract and other growth factors --- p.47 / Chapter Chapter 4 --- Discussion / Chapter 4.1 --- Selection of human hepatic cell line for the detection of mitogenic activity --- p.50 / Chapter 4.2 --- "Mitogenic activity of human bone marrow stromal cells on the selected cell line, SK-Hep-1 cells" --- p.51 / Chapter 4.3 --- Characterization of hepatocyte mitogenic activity of bone marrow stromal cellular extract --- p.52 / Chapter 4.4 --- Performing a preliminary test on the difference between bone marrow stromal cellular extract and other growth factors --- p.53 / Chapter 4.5 --- Possible directions for future investigation --- p.55 / Chapter 4.6 --- Conclusions --- p.56 / Chapter Chapter 5 --- Appendices / Chapter 5.1 --- Reagents and solutiuons --- p.57-64 / Chapter 5.1.1 --- Selection of human hepatic cell line for the detection of mitogenic activity --- p.57 / Chapter 5.1.2 --- "Detection of mitogenic activity of human bone marrow stromal cells on the selected cell line, SK-Hep-1 cells" --- p.59 / Chapter 5.1.3 --- Characterization of hepatocyte mitogenic activity of bone marrow stromal cellular extract --- p.60 / Chapter 5.1.4 --- Performing a preliminary test on the difference between bone marrow stromal cellular extract and other growth factors --- p.61 / Chapter Chapter 6 --- References --- p.65-75