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Theses and Dissertations

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Articles 211 - 224 of 224

Full-Text Articles in Cell and Developmental Biology

Regulation Of Lkb1-Strad-Mo25 Complex Expression And Activation Of Ampk In Skeletal Muscle By Thyroid Hormone, Devon Jack Branvold Jul 2007

Regulation Of Lkb1-Strad-Mo25 Complex Expression And Activation Of Ampk In Skeletal Muscle By Thyroid Hormone, Devon Jack Branvold

Theses and Dissertations

AMP-activated protein kinase (AMPK), a heterotrimeric protein which serves as a metabolic master switch in skeletal muscle, is a research target for the pharmaceutical treatment and prevention of type 2 diabetes. The expression of all of the isoforms of the subunits of AMPK and AMPK activity are increased in skeletal muscle tissue of hyperthyroid rats. Activity of AMPK is regulated by an upstream kinase (AMPKK). The LKB1-STRAD-MO25 complex is a major AMPKK in skeletal muscle. This experiment was designed to determine whether the increase in AMPK activity is accompanied by a thyroid hormone-induced increase in the expression of the LKB1-STRAD-MO25 …

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The Role Of Stat And The Jak/Stat Pathway In Mediating The Effects Of Interleukin-6 On Star Expression, Janae Strickland Mar 2007

The Role Of Stat And The Jak/Stat Pathway In Mediating The Effects Of Interleukin-6 On Star Expression, Janae Strickland

Theses and Dissertations

Cortisol, a hormone produced by a hormone produced by the adrenal gland, is responsible for many regulatory functions in the body. Cortisol release is mediated by adrenocorticotrophic hormone, or ACTH, through the hypothalamus-pituitary-adrenal or HPA axis. This HPA axis is the major release pathway used during acute stress, during which the levels of ACTH parallel those of cortisol. However, in states of chronic stress, the level of ACTH drops dramatically, while cortisol remains high. This study focuses on the pathway of cortisol release during these chronic stress states, specifically examining the role of IL-6 with respect to STATs and the …

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Expression And Function Of Alpha3 And Beta2 Neuronal Nicotinic Acetylcholine Receptor Subunits In Hek-293 Cells, Nathan W. Steinhafel Dec 2006

Expression And Function Of Alpha3 And Beta2 Neuronal Nicotinic Acetylcholine Receptor Subunits In Hek-293 Cells, Nathan W. Steinhafel

Theses and Dissertations

Single-cell real-time quantitative RT-PCR was used to characterize the mRNA expression of rat neuronal nicotinic acetylcholine receptor (nAChR) subunits α3 and β2 in CA1 hippocampus stratum radiatum and stratum oriens interneurons. α3β2 co-expression was detected in 43% of interneurons analyzed. The nAChR subtype α3β2 was transiently expressed in cells derived from the human embryonic kidney cell line 293 at mRNA levels found in the CA1. The functional properties of α3β2 in HEK-293 cells were characterized by whole-cell patch clamping using acetylcholine (ACh) as an agonist. The kinetics of α3β2 channels were further analyzed by altering the level of α3 DNA …

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The Influence Of Membrane Lipid Order On Cell Shape And Microvesiculation In Human Erythrocytes, Laurie Jackson Gonzalez Nov 2006

The Influence Of Membrane Lipid Order On Cell Shape And Microvesiculation In Human Erythrocytes, Laurie Jackson Gonzalez

Theses and Dissertations

Exposure of human erythrocytes to elevated intracellular calcium causes alterations in cell shape and stimulates shedding of the cell membrane in the form of microvesicles. We hypothesized that both the shape transition and microvesiculation are influenced by microscopic membrane physical properties such as lipid order. To test this hypothesis, membrane properties were manipulated by varying the experimental temperature, membrane cholesterol content, and the internal ionic environment. Changes in membrane order were assessed using steady-state fluorescence spectroscopy with an environment-sensitive probe, laurdan. Our observations led us to the following conclusions: 1) the modest temperature dependence of membrane structure observed with laurdan …

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Fgf4 And Wnt5a/Pcp Signaling Promote Limb Outgrowth By Polarizing Limb Mesenchyme, Keri Lynn Low Nov 2006

Fgf4 And Wnt5a/Pcp Signaling Promote Limb Outgrowth By Polarizing Limb Mesenchyme, Keri Lynn Low

Theses and Dissertations

The focus of this study was to elucidate the molecular and cellular mechanisms whereby fibroblast growth factors (FGFs) mediate outgrowth of the limb. Specifically, we examined the epistatic relationship between FGF and Wnt/Planar cell polarity (PCP) signaling in establishing cell polarity as a mechanism for outgrowth. By implanting beads into embryonic limbs and lateral plate mesoderm, we established that FGF activates Wnt5a in a gradient fashion. Once it was established that Wnt5a was expressed at the right time and place to turn on PCP signaling, we investigated the ability of Wnt5a to influence cell migration and/or cell polarity. Our analysis …

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Construction Of A Col11a1 Transgene Vector, Cameron Mckell Beck Aug 2006

Construction Of A Col11a1 Transgene Vector, Cameron Mckell Beck

Theses and Dissertations

Background: Cartilage disorders affect millions of people in the United States alone, with effects ranging from poor skeletal development and joint pain to shortened lifespan and perinatal lethality. Many of these disorders have their root in defects of collagen, type XI collagen being among the most important. A mouse model of such a type XI collagen defect is the chondrodysplasia (cho) mutant. Mice homozygous for this null mutation in the Col11a1 gene do not express the α1 chain of type XI collagen. This results in a functional knockout of type XI collagen, leading to insufficient skeletal development and perinatal lethality. …

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Pka As An Upstream Kinase For Lkb1/Strad/Mo25, Seth Taylor Herway Jul 2006

Pka As An Upstream Kinase For Lkb1/Strad/Mo25, Seth Taylor Herway

Theses and Dissertations

The LKB1/STRAD/MO25 complex (LSMK) has been identified as the major upstream kinase for AMP-activated protein kinase (AMPK). PKA phosphorylates LKB1 at the Ser428 residue in humans and Ser431 residue in mice. We investigated PKA as an upstream kinase for LSMK. LKB1 that had been incubated with PKA prior to incubation with AMPK experienced up to a 51% increase in AMPK Kinase activity compared to LKB1 alone (p < 0.05). When blocked with a PKA Inhibitor, the kinase effect of PKA on LKB1 was eliminated. Rat epitrochlearis muscle tissue incubated with epinephrine experienced no increase in AMPK activity compared with controls indicating that epinephrine does not cause AMPK activity in this type of tissue. In conclusion, phosphorylation by PKA can increase the AMPKK activity of LKB1-STRAD-MO25 in vitro. Because LKB1 has been found to be constitutively active, it is postulated that phosphorylation by PKA may act to enhance LKB1-AMPK interaction and thus achieve its effect.

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The Effects Of 3-Phosphoglycerate And Other Metabolites On The Activation Of Amp-Activated Protein Kinase By Lkb1/Strad/Mo25, William John Ellingson Jul 2006

The Effects Of 3-Phosphoglycerate And Other Metabolites On The Activation Of Amp-Activated Protein Kinase By Lkb1/Strad/Mo25, William John Ellingson

Theses and Dissertations

Skeletal muscle contraction results in the phosphorylation and activation of the AMP-activated protein kinase (AMPK) by an upstream kinase, AMPKK. The LKB1-STRAD-MO25 complex is the major AMPKK in skeletal muscle; however, LKB1-STRAD-MO25 activity is not increased by muscle contraction. This relationship suggests that phosphorylation of AMPK by LKB1-STRAD-MO25 during skeletal muscle contraction may be regulated by allosteric mechanisms. In this study we tested an array of metabolites including glucose-6-phosphate (G6P), fructose-6-phosphate (F6P), fructose 1,6-bisphosphate (F1,6-P2), 3-phosphoglycerate (3PG), glucose-1-phosphate (G1P), glucose-1,6-bisphosphate (G1,6-P2), adenosine diphosphate (ADP), carnitine (Carn), acetyl-carnitine (Acarn), inosine monophosphate (IMP), inosine, and ammonia for allosteric regulation. We found that …

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Properties Of Conductance And Inhibition Of Proton Channels: M2 From Influenza A Virus And Fo From Escherichia Coli Atp Synthase, Jeffrey C. Moffat Jun 2006

Properties Of Conductance And Inhibition Of Proton Channels: M2 From Influenza A Virus And Fo From Escherichia Coli Atp Synthase, Jeffrey C. Moffat

Theses and Dissertations

Proton channels are essential for many of the processes of life. The influenza A viral protein M2 is responsible for sensing the conditions necessary for viral RNA release. The proton-translocating FoF1 ATPase (ATP synthase) uses a proton gradient to drive adenosine triphosphate (ATP) synthesis. We have directly measured proton uptake in vesicles containing reconstituted M2 or FO by monitoring external pH after addition of valinomycin to vesicles with 100-fold diluted external [K+]. This proton flux assay was utilized to quantify proton flux through single M2 and Fo channels. Contrary to previous reports, proton uptake by M2 was not significantly altered …

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The Role Of Fgfr4 In Trigeminal Placode Cell Development, Stephanie Beth Reynolds Mar 2006

The Role Of Fgfr4 In Trigeminal Placode Cell Development, Stephanie Beth Reynolds

Theses and Dissertations

In vertebrate embryos, the ophthalmic trigeminal (opV) placode contributes sensory neurons to the trigeminal ganglion during development of the peripheral nervous system. FGFR4 is expressed transiently in the trigeminal placode as cells undergo an epithelial-mesenchymal transition and begin to migrate toward the condensing ganglion. Because of the restricted spatiotemporal expression of FGFR4 in the opV placode, it was hypothesized that FGFR4 is necessary for the process of epithelial-mesenchymal transition in the opV placode. Using electroporation, an FGFR4 inhibitory gene construct was introduced into 6—10 somite stage chick embryos. This secreted inhibitory form of the FGFR4 gene blocked endogenous FGFR4 signaling, …

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The Role Of Pax3 In Neuronal Differentiation Of The Ophthalmic (Opv) Trigeminal Placode And Neural Tube During Chicken Embryonic Development, James R. Bradshaw Mar 2006

The Role Of Pax3 In Neuronal Differentiation Of The Ophthalmic (Opv) Trigeminal Placode And Neural Tube During Chicken Embryonic Development, James R. Bradshaw

Theses and Dissertations

Pax3 has been used as a valuable marker in research aimed at understanding tissue interactions involved in trigeminal ophthalmic (opV) placode development. While Pax3 expression coincides with opV neuron specification, the function of Pax3 in these cells has not previously been investigated. Splotch mutant mice (which lack Pax3) have a reduced trigeminal ganglion; however it is not clear whether this reduction is due to neural crest or placode cells. We have used electroporation in the chick model system to block or ectopically express Pax3 at key times in opV placode development. Using several markers of placode cell differentiation, we have …

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Phosphorylation Of Skeletal Muscle Acetyl-Coa Carboxylase By Ampk Enhances Palmitoyl-Coa Inhibition, Dustin S. Rubink Dec 2004

Phosphorylation Of Skeletal Muscle Acetyl-Coa Carboxylase By Ampk Enhances Palmitoyl-Coa Inhibition, Dustin S. Rubink

Theses and Dissertations

Acetyl-CoA carboxylase (ACC) catalyzes the formation of malnoyl-CoA, which in turn controls the rate of fatty acid metabolism. ACC beta or 2 has been shown to be localized on the mitochondria in close proximity to carnintine palmitoyl transferase 1 (CPT-1), the enzyme responsible for the influx of acyl-CoA into the matrix where beta oxidation takes place. CPT-1 is inhibited by malonyl-CoA produced by ACC. It has been well documented that AMP activated kinase (AMPK) when activated phosphorylates and inactivates ACC. ACC is controlled allosterically by citrate, which activates, and by palmitoyl-COA, which inhibits. In this study, we asked the question, …

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Mechanism Governing The Cellular Susceptibility To Secretory Phospholipase A2, Lauren Blackburn Jensen Jun 2004

Mechanism Governing The Cellular Susceptibility To Secretory Phospholipase A2, Lauren Blackburn Jensen

Theses and Dissertations

Secretory phospholipase A2 (sPLA2) is an important part of apoptosis and disposal of damaged and dying cells. However, healthy cells are not susceptible to attack by sPLA2. Recent studies have focused on membrane properties necessary to induce susceptibility in both artificial and biological membranes. Hydrolysis of phospholipids by sPLA2 requires at least two preliminary steps: first, adsorption of the enzyme to the cellular membrane, and second, movement of a phospholipid into the active site of the enzyme. We determined the effects of susceptibility on each of the two steps and determined the contributions changing the equilibrium constants have on susceptibility. …

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The Effects Of A One-Tesla Magnet On Human Fibroblast Cell Growth, Ashley Chaplin Jan 2004

The Effects Of A One-Tesla Magnet On Human Fibroblast Cell Growth, Ashley Chaplin

Theses and Dissertations

The controversy regarding the ill effects of electromagnetic fields began in 1979 when Nancy Wertheimer and Ed Leeper claimed to have found a connection between childhood leukemia and power lines. In 1997, a group of researchers led by Martha Linet, M. D., attempted to provide evidence that there was no link between cancer and electromagnetic fields. The study showed that the risk of acute lymphoblastic leukemia did not escalate with increasing electromagnetic field levels in the children's homes. When compared to the Earth's static magnetic field of 0.5 Gauss, these fields were extremely small. Within the past decade, magnets have …

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