Small Molecule Control over Biological Processes

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Title: Small Molecule Control over Biological Processes
Author: Heinecke, Christine Loraine
Advisors: Christian Melander, Committee Chair
David Shultz, Committee Member
Reza Ghiladi, Committee Member
Jonathan Lindsey, Committee Member
Abstract: Myotonic Dystrophy Type 1 (DM1) is a multisystemic neuromuscular disorder characterized by a (CTG)n (n > 50) triplet repeat expansion in the 3’-UTR of the myotonic dystrophy protein kinase gene (DMPK). Transcription produces aberrant poly(CUG) expansions which sequester a family of alternative splicing regulators, the muscleblind proteins (MBNL1-3). In the absence of muscleblind, CUG-binding proteins mediate aberrant splicing leading to the disease pathology. We investigated cyclic peptides for their ability to disrupt a (CUG)54:MBNL1 interaction as a unified approach towards treating DM1. To this end, we performed a phage display selection using a cysteine constrained cyclic heptapeptide library against immobilized (CUG)54, which evolved four highly conserved cyclic peptides. In an effort to develop cellularly irreducible analogs of the cysteine constrained heptapeptides, we performed solid phase peptide synthesis substituting allyl glycine at the N- and C-terminal positions, which were subjected to ring closing metathesis. One of the selected peptides was shown to bind (CUG)54 and disrupt the (CUG)54:MBNL1 interaction characteristic of DM1 to a small extent. Kinamycin D is a potent antitumor antibiotic; however, its biological mode of action is poorly understood. In order to further elucidate the mechanism by which kinamycin D mediates DNA damage, we employed DNA sequencing gel electrophoresis. We have demonstrated that under reducing conditions, acidic media promotes enhanced DNA cleavage. Additionally, our results indicate that kinamycin D is capable of generating reactive oxygen species under acidic pH in the presence of a reducing agent and that DNA cleavage is dependent on trace iron and hydroxyl radicals. Bone biology and architecture are regulated by the interplay between osteoclasts and osteoblasts. Imbalances in this relationship, which favor osteoclastogenic activity are implicated in a variety of skeletal diseases. In an effort to target osteoclasts and inhibit osteoclastogenesis, we have synthesized 1,4-substituted triazole libraries. Qualitative analysis of osteoclast maturation when treated with our compounds indicates some members of our triazole libraries to be the most potent known inhibitors of osteoclastogenesis ever disclosed. Bacterial biofilm infections are implicated as the cause of many persistent and chronic infections due to antimicrobial resistance and virulence factors conferred by their protective extracellular matrices. Bordetella bronchiseptica is a gram-negative bacterial pathogen known to colonize the respiratory tracts of animals forming biofilms that are highly resistant to antimicrobial therapy. We synthesized and screened a library of 1,4-substituted triazoles for modulation of B. bronchiseptica biofilm formation. We identified one small molecule, which displayed agonistic activity towards B. bronchiseptica in multiple nutrient sources.
Date: 2010-04-05
Degree: PhD
Discipline: Chemistry
URI: http://www.lib.ncsu.edu/resolver/1840.16/6246


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