Abstract
BackgroundTen secreted aspartyl proteinase (Sap) genes were identified in Candida albicans. The products of SAP genes are considered to be virulent factors of C. albicans that participated in causing mucocutaneous and systemic candidiasis in humans. Depending on environmental conditions, C. albicans may stay in yeast-form or convert into invasive hypha-form, and these issues may affect the expression of SAP genes. In this study we explored the component(s) of culture media that may affect the expression of hypha-associated SAP genes.ResultsWe demonstrate that glucose levels modulate both the hyphae development and the expression strength of hypha-associated SAP genes (SAP4-6). In contrast to high glucose concentration (2%), lower glucose level (0.1%) is more potent to promote hyphae development and to promptly elicit the expression of hypha-associated Sap proteins during yeast-to-hypha transition of C. albicans. Both Cph1-mediated MAP kinase cascade and Efg1-mediated cAMP/PKA pathway, although the latter seemed dominant, participate in convey the glucose signaling to regulate the expression of hypha-associated SAP genes and this glucose level effect may perform at very early stage of yeast-to-hypha transition. In addition, when C. albicans was co-cultured with THP-1 human monocytes, the engulfed C. albicans was developing hypha efficiently within 1 hr and the expression of hypha-associated Sap proteins could be detected on the distal surface of hyphae.ConclusionWe propose that the glucose level of bloodstream (approximately 0.1%) may be facilitated for stimulation of C. albicans to develop invasive hypha-form and to elicit promptly production of high-level hypha-associated Sap proteins.
Highlights
Ten secreted aspartyl proteinase (Sap) genes were identified in Candida albicans
By adjustment the composition of media and evaluation the effect on the filamentous growth and Saps expression, we demonstrated that glucose levels should be an important environmental factor for induction of hyphae development and modulation the expression level of hypha-associated secreted aspartyl proteinase (SAP) genes during yeast-to-hypha transition and during C. albicans was engulfed by phagocytes
Expression of Sap5 in hypha-inducing conditions For explore the factor(s) that may have an effect on the expression of Sap proteins, we firstly examined whether the hypha-associated Sap proteins can be expressed in commonly used hypha-induced media
Summary
Ten secreted aspartyl proteinase (Sap) genes were identified in Candida albicans. The products of SAP genes are considered to be virulent factors of C. albicans that participated in causing mucocutaneous and systemic candidiasis in humans. In this study we explored the component(s) of culture media that may affect the expression of hypha-associated SAP genes. Candida species are ubiquitous human commensal yeasts that reside in mucosae of oral cavity, gastrointestinal tract, female genitalia and skin. They are part of a healthy individual’s normal microflora; in immunocompromised or disturbed ecosystem of the host, Candida species became pathogenic, causing superficial infection and/or systemic candidiasis [1,2,3]. Hypha-associated SAP4-6 has been investigated as the potent virulent factors in mouse model of systemic candidiasis [20,21]
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