| dc.contributor.author | Mansour, Marc. | en_US |
| dc.date.accessioned | 2014-10-21T12:37:37Z | |
| dc.date.available | 2002 | |
| dc.date.issued | 2002 | en_US |
| dc.identifier.other | AAINQ75706 | en_US |
| dc.identifier.uri | http://hdl.handle.net/10222/55858 | |
| dc.description | The function of specialized cells of the immune system, including lymphocytes, is dependent in part on the expression of cell-specific genes. Subtractive hybridization was previously used in our laboratory to identify natural killer (NK)/T lymphocyte specific transcripts. One partial cDNA isolated by this method and recently named CASP (cytohesin associated scaffolding protein), codes for a protein with at least two protein interaction domains, an N-terminal PDZ and a central coiled coil domain. CASP also contains a novel C-terminal domain of unknown function. CASP's domain profile suggests it may serve as an adaptor protein involved in organizing the higher architecture of a lymphoid-specific signaling complex. CASP was characterized at the genomic, transcriptional, and functional protein levels. Full length CASP cDNA was isolated by 5 ' rapid amplification of cDNA ends (5'RACE), identifying a final 1077 base open reading frame that codes for a 40 kDa CASP protein. The entire CASP gene spanning 29 kilobases was cloned and partially sequenced, revealing an 8 exon/7 intron gene structure. Cloning and sequencing of an additional 4 kilobases of upstream sequence revealed that the CASP promoter region lacks a conventional TATA box but contains binding sites for a number of lymphocyte-specific transcription factors. In accordance with these findings, CASP can be transcriptionally activated in the T cell line Jurkat by T cell receptor (TcR)-mediated signals in an early fashion (3 hours). TcR-mediated CASP activation proceeds through classical immediate TcR signaling pathways, including conventional protein kinase C (PKC) and the mitogen-activated protein kinases (MAPK) ERK (extracellular signal-regulated kinase) and p38. Furthermore, CASP activation is inhibited by the protein synthesis inhibitor cyclohexamide, suggesting a requirement for the de novo synthesis of unidentified transcription factors. | en_US |
| dc.description | Yeast two-hybrid screening of a B cell library identified a CASP interaction with cytohesin, a guanine nucleotide exchange factor (GEF) for the small GTPases of the ADP ribosylation factor (ARF) family. ARF and cytohesin have been implicated in the control of vesicle trafficking in the Golgi and the regulation of endocytosis and actin rearrangement at the plasma membrane. CASP binding to the N-terminal coiled coil of cytohesin was confirmed in vitro and in COS-1 cells. The specificity of CASP's coiled coil is not restricted to cytohesin, however, since it is also capable of interacting with other members of the cytohesin/ARNO family, ARNO and ARNO3. CASP localizes to perinuclear tubulo-vesicular structures that are in close proximity to the Golgi. In epidermal growth factor (EGF)-stimulated COS-1 cells over-expressing cytohesin and CASP, cytohesin recruits CASP to membrane ruffles, revealing a functional interaction between the two proteins. These observations collectively suggest that CASP is a scaffolding protein that facilitates the function of at least one member of the cytohesin/ARNO family in response to specific cellular stimuli, either at the cell periphery or at the level of the Golgi. The inducible and cell type-restricted expression of CASP, suggest it may regulate a lymphoid-specific aspect of vesicular trafficking. | en_US |
| dc.description | Thesis (Ph.D.)--Dalhousie University (Canada), 2002. | en_US |
| dc.language | eng | en_US |
| dc.publisher | Dalhousie University | en_US |
| dc.publisher | | en_US |
| dc.subject | Biology, Molecular. | en_US |
| dc.subject | Biology, Genetics. | en_US |
| dc.title | Genomic and functional characterization of CASP. | en_US |
| dc.type | text | en_US |
| dc.contributor.degree | Ph.D. | en_US |
