Academic literature on the topic 'Proinsulin; Mice; Academic Dissertations'

The two non-allelic preproinsulin genes of the mouse have been cloned and their nucleotide sequences determined. The mouse preproinsulin I gene, like its rat counterpart, has only one intron. Homology between the two mouse genes extends in the 5' direction to about position -500. Homology 3' of the coding sequence terminates shortly after the polyadenylation signal with a dA rich region found in gene I. The coding sequences of the two genes have been compared. The deduced amino acid sequences of the mature hormones are identical to the published protein sequences and to the corresponding sequences of rat insulins I and II. The prepeptides of mouse insulin I and II differ at six positions. However, they maintain hydrophobic cores that are required for transport of the nacent peptide across microsomal membranes. The B-peptide of mouse insulin I differs from insulin II at two positions: at position B9 a proline has replaced a serine, and at position B29 a lysine has replaced a methionine, compared to the sequence of insulin II. The A-peptides of the two hormones are identical. The C-peptide of mouse proinsulin I has a deletion eliminating amino acids C17 (Gly) and C18 (Ala) compared to the sequence of proinsulin II. The presence of this deletion in mature RNA was confirmed through an S1 nuclease assay. The transcriptional start sites for the preproinsulin genes were determined with S1 and Mung Bean nuclease assays, and with a primer extension assay. The data indicate that transcription of the mouse preproinsulin genes starts 6 bp 5' of the site reported for the rat II gene. Single-stranded DNA probes were used to determine the structure of the 3' ends of the preproinsulin mRNAs. Hybridization conditions were used which only allowed each probe to detect its cognate mRNA. Digestion of the resulting DNA-RNA duplex molecules with S1 nuclease followed by gel electrophoresis demonstrated that transcription of mouse preproinsulin I mRNA terminates 18 bases after the polyadenylation signal. Transcription of preproinsulin II mRNA terminates 43 bases after the polyadenylation signal, thus extending 25 bases past the last point of homology between the two genes. The 3' end-specific probes were used in experiments designed to determine the ratio of preproinsulin I and II mRNA in pancreatic extracts of normal, fasted and fasted and refed mice. In all cases the amount of preproinsulin I mRNA exceeded preproinsulin II by about 2.3:1. These results were extended to include an analysis of preproinsulin mRNA from freshly isolated islets and islets incubated for 48 hours in the presence of 2.8 mM or 16.7 mM glucose. With both high and low glucose concentrations, the amount of preproinsulin I mRNA exceeded preproinsulin II by about 2.3:1. The mouse islets were also incubated with 3H-leucine and the ratio of insulin I and II determined after fractionation by HPLC. Unlike the mRNA results, the level of insulin II, within the islets and secreted into the media, exceeded insulin I by about 2:1 under all conditions. The available preproinsulin prepeptide amino acid sequences have been compared. The sequence of mouse I prepeptide differs from most other insulin prepeptides at amino acid position 4. At that position a tryptophan residue that is conserved in most insulin prepeptides has been replaced by a leucine in the mouse I prepeptide. This change causes a shift in the hydropathy profile in that region of the mouse insulin I prepeptide making it more hydrophobic. Every other insulin prepeptide is relatively hydrophilic at that position. This difference is postulated to interfere with signal recognition particle mediated regulation of translation and/or transport of nacent mouse preproinsulin I to microsomal membranes, and nay account for the discordant mRNA-peptide ratios. The structure of the insulin genes in a number of myomorph rodents has been examined. The data indicate that only members of the sub-family Murinae have two insulin genes.

This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.
Bachelors
Burnett College of Biomedical Sciences
Molecular and Microbiology

Thesis (Ph. D.)--University of California, San Diego, 2006.
Title from first page of PDF file (viewed December 6, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.

Thesis (M.S.)--University of California, San Diego, 2009.
Title from first page of PDF file (viewed January 9, 2009). Available via ProQuest Digital Dissertations. Includes bibliographical references (p. 25-26).

Acquired Immune Deficiency Syndrome (AIDS), a progressive immunodeficiency induced by Human Immunodeficiency Virus (HIV), frequently sets the stage for life-threatening tumors and opportunistic infections. The proposed study focuses on the immunological changes associated with HIV infection. Often superimposed diarrhea, causing malabsorption and malnutrition, leads to further immunosuppression and accelerated deterioration in many patients. The pathomechanism of Cryptosporidium-induced diarrhea is poorly understood and its relation to AIDS urgently requires investigation. We used LP-BM5 murine leukemia virus (MuLV)-infected C57BL/6 mice to model AIDS and thereby study the immunological changes in human retrovirus infection. Production of Th1 cytokines (IL-2 and IFN-γ) was suppressed, whereas Th2 cytokine production (IL-4, IL-5, IL-6, and IL-10) was enhanced in spleen and mesenteric lymph nodes (MLN) during retrovirus infection. However, increased secretion of IFN-γ in the MLN of retrovirus-infected mice may represent incremental production and release by non-Th1 cells. Lymphoid cell population changes in gut-associated lymphoid tissues (GALT) were documented 4 months after retrovirus infection. Total lymphoid cell numbers decreased in Peyer's patches and CD4⁺ cell numbers decreased in the intestinal lamina propria (ILP). Total lymphoid cell numbers increased in MLN but the relative percentages of surface IgA⁺, cytoplasmic IgA⁺ (cIgA⁺), and cIgM⁺ cells were decreased. Cryptosporidium infestation in retrovirus-infected mice decreased following the administration of pooled bovine colostrum containing a high titer of antibody demonstrating the potential efficacy of passive humoral immunity. Changes in the host cellular immune apparatus, following Cryptosporidium infection, were as follows: (1) increased γδ-TCR⁺ cells in the ILP 6 and 10 days post-infection, (2) decreased CD4⁺ cells in the ILP and intraepithelium 10 days post-infection, (3) reduced IgA⁺ and IgG⁺ cells in the ILP 6 and 10 days post-infection, and (4) increased IgE⁺ cells 6 days post-infection. This altered cellular profile indicates the potential for aberrant cytokine production which may be responsible for the compounded immunodeficiency during retrovirus infection. Overall, the findings underscore the importance of understanding both humoral and cell-mediated immunological influences before the rational development of a therapy against opportunistic cryptosporidial infection in AIDS patients can be undertaken.

Thesis (Ph. D.)--University of California, San Diego, 2009.
Title from first page of PDF file (viewed March 13, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.