Much research has been conducted and significant progress has been made in understanding how signals are transmitted in response to extracellular stimuli. Continued research is necessary to elucidate how specificity in signaling from the cell surface is achieved and to understand how disruption of such signaling pathways leads to disease. The question of specificity is important since many of the same proteins can be activated by different stimuli in a variety of signaling pathways. One means of achieving specificity would be for different cell types to express different sets of proteins that interact with "common" proteins such as GRB2, Shc, and Ras. There were two goals to my dissertation research. The first goal was to study disease which results from perturbation of the EGF receptor. The second was to explore the possibility that signals generated in response to EGF or other stimuli might be transmitted through MAP kinase proteins other than ERKs 1 and 2. Chapter II of this thesis centers around further analyzing the disease potential of erbB in chickens. I have conducted oncogenicity tests with an erbB oncogene that contains no mutations, only the characteristic N-terminal truncation. My studies have revealed that truncation of the EGF receptor (erbB) can induce tumorigenesis of the kidney as well as the erythroblastosis originally associated with erbB. Previous studies have only found kidney tumors in association with mutated forms of the erbB oncogene. Furthermore, I have demonstrated that mutational removal of a negative regulatory serine phosphorylation site increases the number of wing web tumors caused by the erbB oncogene. Chapter III describes the identification of the Ser/Thr protein kinase p56 KKIAMRE and characterization of p56 KKIAMRE and p42 KKIALRE. These kinases have homology to the MAP kinase group and contain the conserved Thr-Xaa-Tyr dual phosphorylation site. I have demonstrated that both kinases can be activated by treatment of cells with EGF. Interestingly, phosphorylation of Thr and Tyr in the Thr-Xaa-Tyr motif is not necessary for EGF stimulated activity.

In the first part of this thesis, the expression of the Drosophila homolog (DER) of the vertebrate epidermal growth factor (EGF) receptor was investigated during development of the optic lobe in relation to cell division patterns. Patterns of Der expression were determined by in situ hybridization while the patterns of cell division were determined by incorporation of bromodeoxyuridine. Der transcripts within the CNS are located almost exclusively within a small subset of cells in the optic lobe. These cells represent the precursors of the lamina, the outermost synaptic region of the optic lobe. Laminal cells are postmitotic, being derived from the terminal cell divisions of ganglion mother cells in adjacent proliferation centers. Induction of Der expression coincides with the birth of laminal cells and continues through the first day after puparium formation, a time when extensive interactions between photoreceptor cell axons and developing laminal cells occur. By forty-eight hours postpupariation, the lamina is well developed and Der transcripts are no longer present. Mutant Der alleles do not affect the structure of the lamina in the larval stage but minor optic lobe defects are seen in adults bearing the Elp1 allele of the Der gene. These results suggest a non-mitotic role for DER in the development of the lamina. In the second part of this thesis, a P-element mutagenesis was carried out to identify second site mutations that suppress the Elp phenotype. Elp represents a hypermorphic mutation in the Der gene. Analysis of Elp protein by protein blotting indicates that the increased activity is not due to an increased level of gene expression. Three dominant mutations that suppress the Elp phenotype were identified and designated as Su(Elp)2, Su(Elp)3-1, and Su(Elp)3-2. Su(Elp)2 is a recessive embryonic lethal mutation which also affects viability of heterozygotes. Embryos collected from Su(Elp)2 parents have both cuticle and CNS defects. The cuticle is frequently missing or aberrant. The CNS is often hypertrophied and aberrant. Su(Elp)2 does not enhance Der loss of function mutations or suppress torRL3. Su(Elp)3-1 is a post-embryonic recessive lethal mutation. The Su(Elp)3-1 mutation reduces the severity of the eye pattern defects in Elp homozygotes and increases the viability of Elp homozygotes. In addition, Su(Elp)3-1 rescues the viablility of Elp/flb trans-heterozygotes. Su(Elp)3-1 is complex and may consist of multiple P-element insertions that act as suppressors of Elp. Su(Elp)3-2 also appears to be a complex suppressor mutation.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第19365号 / 医博第4042号 / 新制||医||1011(附属図書館) / 32379 / 新制||医||1011 / 京都大学大学院医学研究科医学専攻 / (主査)教授 椛島 健治, 教授 佐藤 俊哉, 教授 山田 泰広 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

The objective of the study reported here was to document the distribution of epidermal growth factor receptor (EGFr) and quantitate receptor density in normal as well as ulcerated equine gastric squamous mucosa. Fifteen horses with endoscopically normal stomachs were divided into three equal groups. Group 1 was a normal control. A protocol that alternated 24 hour periods of free-choice hay with 24 hours of feed deprivation was utilized to induce squamous mucosal gastric ulceration in Group 2 (48 hours total off-feed) and Group 3 (96 hours total off-feed). Gastric tissue was collected from 3 stomach locations at post-mortem examination and an avidin-biotin immunoperoxidase technique was developed to stain the formalin-fixed tissue for EGFr. A computerized image analysis system was used to measure EGFr area and mean intensity values at four sites within the epithelium from the basal cell layers to the lumen in the ulcer/erosion margin, erosion bed, and 10-14 mm distant from the lesion. / Master of Science