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Inhibitory Mechanisms of Pyrvinium Pamoate on Candida albicans
Başlık:
Inhibitory Mechanisms of Pyrvinium Pamoate on Candida albicans
Yazar:
Macias, Marlene, author.
ISBN:
9780438070547
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (64 pages)
Genel Not:
Source: Masters Abstracts International, Volume: 57-06M(E).
Advisors: Hyunsook Park Committee members: Edward Eivers; Robert Nissen; Edith Porter.
Özet:
Candida albicans is a dimorphic fungus that is part of the human microbiota of the skin and mucosal epithelial cells. Normally, this microbe poses no threat in a healthy person but can cause oral candidiasis and systemic infections in immunocompromised individual. Systemic candidiasis account for about 44.8% of healthcare associated infections in the ICU. With its recent increase in resistance, the mortality rate has risen to 71-79%% in the reported cases. Its pathogenicity is linked to its ability to transition between yeast and hyphae forms since the germ tube expresses secreted aspartyl proteinases that help in degrading the epithelial and endothelial cells. In recent years, C. albicans has gained resistance to the anti-fungal agents currently used to treat candidiasis and consequently, candidiasis is now the fourth leading cause of death among hospital acquired infections. Hence, the importance of developing new anti-fungal medications has risen in response to the increased resistance of C. albicans. An FDA approved drug named Pyrvinium Pamoate (Pyr) has been found to have antifungal activity in biofilm formation. In helminth infections and cancer studies, Pyr is known to activate Casein Kinase 1 (CK1) and has also been found to inhibit AKT/PKB resulting in GSK3 activation. Both mechanisms lead to Beta-catenin degradation which inhibition Wnt signaling, leading to decreased cell proliferation and differentiation. However, studies involving the inhibitory mechanisms of Pyr on C. albicans are limited. C. albicans does not have Wnt signaling, but it expresses homologous proteins to those found in the pathway. Hence, the purpose of this study was to gain insight on the mechanisms that Pyr utilizes to inhibit the cellular fitness of C. albicans. Based on the two modes of action, I hypothesized that Pyr activity towards C. albicans would result in the upregulation in the gene expression of either YCK2 or MCK1 which are homologs of CK1 and GSK3. To further analyze the inhibitory effects, I measured the cell growth over period of ten hours, observed any changes in growth rate, morphology and cell wall architecture, and analyzed the expression of morphological change and virulence related genes in the Pyr treated strain. The results showed that the cell growth rate of C. albicans was decreased in the presence of Pyr in a does dependent manner. By the tenth hour, t there was an 72% decrease in samples with 2.5 microg/mL of Pyr and an average 94% decrease in the 5.0 microg/mL sample. The yeast cells were not budding out normally and the cells were much smaller compared to the DMSO control samples at 2.5 microg/mL. Furthermore, the cells resulted in more clumping and at 5.0 microg/mL. In hyphae cells, the 2.5 microg/mL concentration severely affected the filamentous growth of the hyphal germ tube and completely inhibited hyphal transition at the 5.0 microg/mL. The calcofluor white (CFW) staining in yeast showed that chitin began to accumulate in both 2.5 microg/mL and 5.0 microg/mL. Similarly, the CFW stain in hyphae demonstrated that there was an immense abundance of chitin accumulation occurring throughout the cell both 2.5 microg/mL and 5.0 microg/mL. , in the sample containing 2.5 microg/mL while the 5.0 microg/mL showed little chitin deposition, suggesting that Pyr in negatively affecting the Hyphal cell wall, resulting in more chitin accumulation as a compensatory mechanism of action. The transcriptional analysis showed a significant dose dependent increase of YCK2 expression in both one hour and three hour yeast samples and at one hour in Hyphae form, indicating that YCK2 is being highly expressed in response to the environmental stressor and possibly suggesting that Pyr affects C. albicans by inducing YCK2 expression. The gene expression of both ALS3 and HWP1 was significantly decreased in hyphal inducing conditions with no gene expression occurring at all at concentration of 2.5 microg/mL and 5.0 microg/mL in the three hour samples. These two hyphae specific genes are crucial for morphogenesis and biofilm formation and the downregulation indicates that Pyr affects the cell wall by inhibiting the gene expression of ALS3 and HWP1, therefore, leading to inhibition in morphological transition and biofilm formation.
Notlar:
School code: 0962
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(692752.1) | 692752-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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