Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 77-87).

Univ., Diss., 2006--Frankfurt (Main)

Thesis (Ph.D.)--Medical College of Ohio, 2005. / "In partial fulfillment of the requirements for the degree of Doctor of Philosophy in Medical Sciences." Major advisor: William Maltese. Includes abstract. Document formatted into pages: iv, 134 p. Title from title page of PDF document. Bibliography: pages 107-132.

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (leaves 94-116).

Thesis (Ph. D.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains ix, 224 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.

Glycogen Synthase Kinase 3 (GSK3), a serine/threonine kinase initially characterized in the context of glycogen metabolism, has been repeatedly realized as a multitasking protein that can regulate numerous cellular events in both metazoa and protozoa. I recently found GSK3 plays a role in regulating chemotaxis, a guided cell movement in response to an external chemical gradient, in one of the best studied model systems for chemotaxis - Dictyostelium discoideum. It was initially found that comparing to wild type cells, gsk3- cells showed aberrant chemotaxis with a significant decrease in both speed and chemotactic indices. In Dictyostelium, phosphatidylinositol 3,4,5-triphosphate (PIP3) signaling is one of the best characterized pathways that regulate chemotaxis. Molecular analysis uncovered that gsk3- cells suffer from high basal level of PIP3, the product of PI3K. Upon chemoattractant cAMP stimulation, wild type cells displayed a transient increase in the level of PIP3. In contrast, gsk3- cells exhibited neither significant increase nor adaptation. On the other hand, no aberrant dynamic of phosphatase and tensin homolog (PTEN), which antagonizes PI3K function, was observed. Upon membrane localization of PI3K, PI3K become activated by Ras, which will in turn further facilitate membrane localization of PI3K in an F-Actin dependent manner. The gsk3- cells treated with F-Actin inhibitor Latrunculin-A showed no significant difference in the PIP3 level. I also showed GSK3 affected the phosphorylation level of the localization domain of PI3K1 (PI3K1-LD). PI3K1-LD proteins from gsk3- cells displayed less phosphorylation on serine residues compared to that from wild type cells. When the potential GSK3 phosphorylation sites of PI3K1-LD were substituted with aspartic acids (Phosphomimetic substitution), its membrane localization was suppressed in gsk3- cells. When these serine residues of PI3K1-LD were substituted with alanine, aberrantly high level of membrane localization of the PI3K1-LD was monitored in wild type cells. Wild type, phosphomimetic, and alanine substitution of PI3K1-LD fused with GFP proteins also displayed identical localization behavior as suggested by the cell fraction studies. Lastly, I identified that all three potential GSK3 phosphorylation sites on PI3K1-LD could be phosphorylated in vitro by GSK3.

Phosphatidylinositol 3-kinase δ (PIK3δ) is a tyrosine kinase essential for B cell survival, making it an important target in the treatment of chronic lymphocytic leukemia. Idelalisib is an inhibitor of PIK3δ demonstrating initial success in disease response, but is now shown to have a decreased overall survival and life-threatening serious adverse events. The following is an unfortunate case of a grade III adverse skin reaction secondary to idelalisib with the likely complication of methicillin-resistant Staphylococcus aureus bacteremia.

Aim: To explore the protective effects and involved mechanisms of two angiogenic growth factors, vascular endothelial growth factor (VEGF165) and angiopoietin-1 in cardiac myoblasts. Methods: Replication-deficient adenovirus encoding for human VEGF165 (Ad-VEGF165) or angiopoietin-1 (Ad-Ang1) were transfected into H9C2 cardiac myoblasts. Recombinant adenovirus encoding for green fluorescent protein (Ad-GFP) was used as vehicle control. Twenty-four hours later, cell apoptosis was induced by 300 μmmol of H2O2. Genomic DNA was extracted and DNA fragmentation was analyzed in 1.6% agarose gels. Phosphatidylinositol-3 kinase(PI-3 K) activity and bcl-2 expression level were investigated in H9C2 after gene transfection 24 hours later by an immol/Lunoprecipitated kinase assay and Western blot assay respectively. The effect of wartmannin, a specific inhibitor of PI-3 K, on DNA fragmentation, PI-3 K activity and bcl-2 expression was also analyzed by a pre-treatment of 30 minutes before transfection. Results: Apoptotic DNA fragmentation induced by H2O2 was significantly inhibited by the transfaction of Ad-VEGF165 and/or Ad-Ang1 but then aborted by the pretreatment of wartmannin. PI-3 K activity was significantly elevated after Ad-VEGF165 + Ad-Ang1 transfection as compared to Ad-GFP transfection group(2.60 vs 1.32, P < 0.01). Anti-apoptotic factor bcl-2 expression was upregulated in Ad-VEGF165 (2.1-fold), Ad-Ang1 (1.7-fold) and Ad-VEGF165 + Ad-Ang1 (1.7-fold) treated groups as compared to Ad-GFP transfection group. Wortmannin suppressed PI-3 K activiation induced by Ad-VEGF165 (from 1.83 to 0.69, P < 0.05). Ad-Ang1 (from 1.80 to 0.97, P = 0.07) or Ad-VEGF165a + Ad-Ang1 (from 2.60 to 0.42, P < 0.01). However, upregulation of bcl-2 induced by Ad-VEGF165 and/or Ad-Ang1 was not aborted by wortmannin pretreatment. Conclusions: VEGF165 and/or Ang1 can protect cardiac myoblasts from apoptosis induced by H2O2 throught PI-3 K and bcl-2 pathway. The anti-apoptotic function of either VEGF165 or Ang1 could be served as a now therapeutic target including their angiogenic benefits.

One of the consequences of G-protein-coupled receptor activation is stimulation of phosphoinositol metabolism, leading to the generation of IP 3 and its metabolites 1,3,4,5-tetrakisphosphate (IP4) and inositol 1,2,3,4,5,6-hexakisphosphate (IP6). Previous reports indicate that high inositol polyphosphates (IP4 and IP6) are involved in clathrin-coated vesicular recycling. In this study, we examined the effects of IP4 and IP6 on spontaneous transmitter release in the form of miniature endplate potentials (MEPP) and on enhanced vesicular recycling by high K+ at frog motor nerve endings. In resting conditions, IP4 and IP6 delivered intracellularly via liposomes, caused concentration-dependent increases in MEPP frequency and amplitude. Pretreatment with the protein kinase A (PKA) inhibitor H-89 or KT 5720 reduced the IP4-mediated MEPP frequency increase by 60% and abolished the IP6-mediated MEPP frequency increases as well as the enhancement in MEPP amplitude. Pretreatment with antibodies against phosphatidylinositol 3-kinase (PI 3-K), enzyme also associated with clathrin-coated vesicular recycling, did not alter the IP4 and IP6-mediated MEPP frequency increases, but reduced the MEPP amplitude increase by 50%. In our previous reports, IP3, but not other second messengers releasing Ca2+ from internal Ca2+ stores, is able to enhance the MEPP amplitude. In order to dissociate the effect of Ca2+ release vs. metabolism to IP4 and IP 6, we evaluated the effects of 3-deoxy-3-fluoro-inositol 1,4,5-trisphosphate (3F-IP3), which is not converted to IP 4 or IP6. 3F-IP3 produced an increase then decrease in MEPP frequency and a decrease in MEPP amplitude. In elevated vesicle recycling induced by high K+-Ringer solution, IP4 and IP6 have similar effects, except decreasing MEPP frequency at a higher concentration (10-4 M). We conclude that (1) high inositol polyphosphates may represent a link between IP3 and cAMP pathways; (2) the IP3-induced increase of MEPP amplitude is likely to be due to its high inositol metabolites; (3) PI 3-K is not involved in the IP 4 and IP6-mediated MEPP frequency increases, but may be involved in MEPP size.

The potassium channels IK and IK1, responsible for the action potential repolarization and resting potential respectively, are altered during cardiac hypertrophy. The activation of insulin-like growth factor-I (IGF-I) during hypertrophy may affect channel activity. The aim was to examine the modulatory effects of IGF-I on IK and IK1 through mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K) pathways during hypertrophy. With the use of specific inhibitors for ERK1/2 (PD98059), p38 MAPK (SB203580) and PI3K/Akt (LY294002), Western blot and whole cell patch-clamp were conducted on sham and aorto-caval shunt-induced hypertrophy adult rat myocytes. Basal activation levels of MAPKs and Akt were increased during hypertrophy. Acute IGF-I (10-8 M) enhanced basal activation levels of these kinases in normal hearts but only those of Akt in hypertrophied ones. IK and IK1 activities were lowered by IGF-I. Inhibition of ERK1/2, p38 MAPK, or Akt reduced basal IK activity by 70, 32, or 50%, respectively, in normal cardiomyocytes vs. 53, 34, or 52% in hypertrophied ones. However, basal activity of IK1 was reduced by 45, 48, or 45% in the former vs. 63, 43, or 24% in the latter. The inhibition of either MAPKs or Akt alleviated IGF-I effects on IK and IK1. We conclude that basal IK and IK1 are positively maintained by steady-state Akt and ERK activities. K+ channels seem to be regulated in a dichotomic manner by acutely stimulated MAPKs and Akt. Eccentric cardiac hypertrophy may be associated with a change in the regulation of the steady-state basal activities of K+ channels towards MAPKs, while that of the acute IGF-I-stimulated ones toward Akt. .