As the major source of energy in the cell, mitochondria need to be able to effectively communicate their status to the nucleus. Defects in this process can have profound effects on the health of an organism and may affect its lifespan. The mitochondrial enzyme CLK-1 is required to produce ubiquinone for respiration and CLK-1 loss of function mutants have been shown to increase lifespan in both Caenorhabditis elegans and mammals. In this thesis, it is demonstrated that in addition to its mitochondrial role, CLK-1 also localises to the nucleus in C. elegans. This nuclear localisation is mediated by reactive oxygen species (ROS) and can be blocked using anti-oxidant treatment. In the nucleus CLK-1 regulates gene expression to suppress ROS production, suppresses the mitochondrial unfolded protein response and regulates lifespan. The importance of CLK-1 enzymatic activity for its nuclear role was also tested and it appears that enzymatic function is required to regulate ROS homeostasis but not for lifespan regulation. Interestingly, in fertile adult hermaphrodites nuclear CLK-1::GFP was only detected during the reproductive period. This suggests that there is a second mechanism regulating its localisation. This research indicates that CLK-1 may be part of a homeostatic regulatory mechanism that acts to suppress activation of stress responses in response to minor fluctuations in ROS levels.

No description available.

Mutations in the clk-1, clk-2, clk-3 and gro-1 genes in Caenorhabditis elegans show alterations in developmental and behavioral timing and lifespan, collectively termed the Clk phenotype. While the clk-1, clk-2, and gro-1 genes have been cloned, clk-3 gene has not been identified. Gene expression changes in clk-3 mutant worms were determined using microarray expression data. I examined genes in the region to which clk-3 gene maps, for strongly reduced expression in the clk-3 mutants and identified thirteen clk-3 candidate genes. RNAi feeding vectors for all these candidate genes were picked and cultured from the RNAi library. Knock-down worm strains were generated by feeding RNAi and analyzed for Clk phenotypes. Of all the candidate genes tested, the Y48E1B.5 gene showed the most similar phenotypic profile to the clk-3 mutants. The Y48E1B.5 gene shows weak homology to a mammalian mitochondrial ribosomal protein. Primers were designed to amplify all 9 exons of the Y48E1B.5 gene. Sequence analysis was carried out on the resulting PCR products from clk-3 mutants. An amino acid change was found in exon 4.

<p dir="ltr">Cancer is the second leading cause of death worldwide, and there is a continued need for effective treatments to combat the disease. A key challenge in cancer therapy persists in the form of therapeutic resistance. While kinase inhibitors (KIs) have shown promise in treating cancer patients with dysregulated protein kinases, treatment failures are common, highlighting the urgent need to address this issue. Despite the approval of 80 protein kinase inhibitors by the United States Food and Drug Administration (FDA), and numerous others in clinical trials, the chemical space explored for protein kinase inhibitors remains limited. Most FDA-approved kinase inhibitors share common core moieties, such as indazole, quinoline, pyrazole, and pyrimidine, indicating a lack of diversification in drug development in this area.</p><p dir="ltr">Efforts to expand the chemical space have led to the identification of a novel 3<i>H</i>-pyrazolo-[4,3-<i>f</i>]quinoline core by the Sintim group. This scaffold can be efficiently synthesized through the Doebner–Povarov multicomponent reaction using readily available ketones, heteroaromatic aldehydes, and 5-aminoindazole. This multicomponent chemistry affords small molecules which inhibit disease-associated protein kinases with sub-nanomolar IC₅₀ values. Additionally, the scaffold presents a unique opportunity to tune for selectivity via judicious substitution patterns, allowing us to target numerous disease-driving kinases, such as FLT3, haspin, and CLK, with the use of simple multi-component chemistry.</p><p dir="ltr">From this work emerged lead amide-containing compound HSK205, which potently inhibits FLT3 and haspin and shows impressive potencies against FLT3-driven acute myeloid leukemia cell lines, with GI₅₀ values between 2 and 20 nM. Western blot analyses indicate that HSK205 inhibits the phosphorylation of FLT3 and histone H3 (substrate of haspin) in Molm-14 AML cells. Further exploration led to the discovery of lead CLK inhibitors, such as HSK1132 and HSK3110, which inhibit the growth of multiple myeloma cell lines <i>in vitro</i> with GI₅₀ values as low as 17 nM. Additionally, these compounds are orally bioavailable and reduce the growth of multiple myeloma RPMI-8226 xenograft model in mice by 69%.</p>

Thesis (DTech (Internal Auditing))--Cape Peninsula University of Technology, 2016. / Although South African Small, Medium and Micro Enterprises (SMMEs) play an imperative role in the stimulation of the national economy, previous research studies show that these business entities have severe sustainability problems as approximately 75% of these business entities fail after being in operation for only three years. The latter dispensation is pinned on the belief that South African SMMEs make use of inadequate and/or ineffective internal control systems. Taking into account that a system of internal control comprises five inter-related elements, as well as the fact that management is responsible for the internal control in their respective business entities, this research study placed focus on determining the relationship which exist between the managerial conduct of management and the internal control activities evident in South African fast-moving consumer goods (FMCGs) SMMEs. In order to achieve the latter, two literature reviews were conducted (see Chapter 2 and Chapter 3) and, in turn, quantitative data were collected through a questionnaire and analysed accordingly through both descriptive statistics and inferential statistics (see Chapter 5). Based on the analysed data, a very weak negative statistically significant relationship was identified between the managerial conduct of management and the internal control activities evident in South African FMCG SMMEs. Regardless of the very weak negative statistically significant identified relationship, the results vindicate the importance of appropriate managerial conduct, as well as adequate and effective internal control activities. Stemming from this, a new proposed framework (Control Legacy-K Framework) was developed which South African FMCG SMMEs can implement to help enhance their overall sustainability which, in turn, can help them fortify their continuation rate in the foreseeable future (see Chapter 6).

Depuis plus d’un siècle, la chimie hétérocyclique représente l’un des plus vastes domaines de recherche en chimie organique. En particulier, les hétérocycles bicycliques fusionnés à 5 chaînons, contenant à la fois des atomes de soufre et d’azote, présentent, de par leur rareté et leur potentiel biologique, un champ d’intérêt croissant pour les équipes de recherche et développement académiques ou des entreprises pharmaceutiques. Parmi les nombreux composés bicycliques [5-5], notre étude s’est focalisée sur le noyau imidazo[2,1-b][1,3,4]thiadiazole décrit sporadiquement dans la littérature et pour lequel les voies d’accès actuelles ne se limitent qu’à une seule méthode faisant intervenir une étape de cyclisation et des conditions drastiques. Ce verrou entraine inéluctablement une faible diversité fonctionnelle autour de cet hétérocycle, restreignant ainsi les domaines d’applications notamment biologiques. Afin de pallier à cette problématique, nous avons initié une étude de la réactivité de chacune des trois positions fonctionnalisables du bicycle imidazo[2,1-b][1,3,4]thiadiazole, développant ainsi diverses réactions pallado-catalysées (Suzuki-Miyaura, CH-arylation, Buchwald-Hartwig), de substitution nucléophile aromatique et de Pictet-Spengler. L’étude des propriétés biologiques des différents composés synthétisés et hautement valorisables durant ces travaux a abouti à la découverte de deux séries de molécules inhibant sélectivement les kinases DYRK-1A et CLK-1, deux protéines d’intérêt dans le traitement des affections du système nerveux central (neuropathies, Alzheimer…). / For more than a century, heterocyclic chemistry is one of the largest area in organic chemistry research. In particular, because of their rarity and their biological potential, [5-5] fused ring heterocycles containing both sulfur and nitrogen atoms are a large area of interest for both academic and industrial research and development teams. Among these numerous [5-5] bicycles, our study is focused on imidazo[2,1-b][1,3,4]thiadiazole scaffold, which is quite few described in the literature and whose pathways are limited to almost one method involving a cyclisation step and drastic conditions. This lock leads inevitably to low functional diversity around this heterocycle, thus restricting its applications, including biological. In order to overcome this problematic, we then initiated the reactivity study of each three positions of the bicycle imidazo[2,1-b][1,3,4]thiadiazole, developing thereby several palladium couplings (Suzuki-Miyaura, direct arylation, Buchwald-Hartwig), as well as aromatic nucleophilic substitution and Pictet-Spengler reaction. The study of the biological properties of the different compounds synthesized in this work and highly valuable led to the discovery of two series of molecules, inhibiting selectively DYRK-1A and CLK-1, two kinases of interest in the treatment of dysfunction of central nervous system (neuropathies, Alzheimer…).