| dc.contributor.author | Morris, Stephen J. | en_US |
| dc.date.accessioned | 2014-10-21T12:37:50Z | |
| dc.date.available | 1992 | |
| dc.date.issued | 1992 | en_US |
| dc.identifier.other | AAINN87482 | en_US |
| dc.identifier.uri | http://hdl.handle.net/10222/55361 | |
| dc.description | Phosphoinositides are quantitatively minor phospholipids which are part of an intracellular signal transduction system with broad effects upon cell function. Phosphoinositide metabolism, especially as relating to availibility of phosphoinositides for participation in signal transduction, was investigated in two cultured cell lines (N1E-115 mouse neuroblastoma, and C6 rat glioma). | en_US |
| dc.description | The hypothesis that the small portion of cellular phosphoinositide participating in signal transduction might be preferentially recycled within the plasma membrane was tested. The subcellular distribution of all enzymes mediating phosphoinositide turnover was assessed in a purified plasma membrane fraction. A small but significant proportion of PtdIns(4,5)P$\sb2$-specific phospholipase C was located in the plasma membrane but only two of the five enzymes required to replace PtdIns(4,5)P$\sb2$ (DAG kinase and PtdIns(4)P 5-kinase) also were present. CTP:phosphatidate cytidylyltransferase and PtdIns synthase were located exclusively in a microsomal fraction containing enriched levels of endoplasmic reticulum markers. Thus, DAG from agonist-stimulated cleavage of PtdIns(4,5)P$\sb2,$ or phosphatidic acid formed from it, must be transferred to the endoplasmic reticulum for conversion to PtdIns. Accordingly, PtdIns resynthesis is not required for phosphoinositide-mediated signal transduction. Plasma membrane of N1E-115 cells is incapable of forming PtdIns from 1-acyl-lysoPtdIns. Microsomal 1-acyl-lysoPtdIns synthase activity is most active with 20:4-CoA. Therefore, the PtdIns deacylation/reacylation cycle does not take place in the plasma membrane and formation of archidonate enriched PtdIns occurs before PtdIns is transported to the plasma membrane. | en_US |
| dc.description | In vitro activities of many of the enzymes acting upon phosphoinositides are modulated by polyamines. The hypothesis that polyamines regulate phosphoinositide metabolism was investigated using cells labelled in culture with ($\sp{32}$P) Pi. Intracellular polyamines increased several-fold when cells were exposed to exogenous polyamines. ($\sp{32}$P) Phosphoinositide synthesis was increased in cells exposed to putrescine for 6 hours. In vitro experiments confirmed that polyamines stimulate PtdIns synthase. PtdIns(4,5)P$\sb2$ turnover was inhibited by spermine. However, neither agonist-stimulated PtdIns synthesis nor agonist-stimulated PtdIns(4,5)P$\sb2$ hydrolysis were affected by polyamines. | en_US |
| dc.description | The biochemical basis of malignant hyperthermia (MH), a disorder leading to hypersensitivity to anaesthetics, was investigated using leukocytes and lymphoblasts from human patients susceptable to MH. Contrary to data from the pig model of the disease, human MH patients had normal levels of Ins(1,3,5)P$\sb3$ 5-phosphatase. | en_US |
| dc.description | Thesis (Ph.D.)--Dalhousie University (Canada), 1992. | en_US |
| dc.language | eng | en_US |
| dc.publisher | Dalhousie University | en_US |
| dc.publisher | | en_US |
| dc.subject | Biology, Neuroscience. | en_US |
| dc.subject | Biology, Cell. | en_US |
| dc.title | Phosphoinositide metabolism in cultured cells of neuronal and glial origin. | en_US |
| dc.type | text | en_US |
| dc.contributor.degree | Ph.D. | en_US |
