Chlamydospore formation in Candida albicans and Candida dubliniensis– an enigmatic developmental programme

Abstract

Chlamydospore formation has served for a long time for identification of the human fungal pathogen Candida albicans, but the biological function of these structures still remains a secret. They have been proposed to allow survival in harsh environmental conditions, but this assumption remains to be proven. Chlamydospores are produced only by the two closely related species C. albicans and Candida dubliniensis, whose natural habitats are humans and warm-blooded animals, but not by other Candida species that are also found outside animal hosts. However, no role in the pathogenesis of Candida infections has been assigned to these unusual cells and only a limited number of studies have been conducted in the past to unravel their function. The development of new molecular tools and the recent discovery of mating in C. albicans have also restimulated investigations to understand the morphogenesis and function of chlamydospores. The finding that chlamydospore formation is differentially controlled by certain environmental signals in C. albicans and C. dubliniensis has opened new approaches to study the regulation of this morphogenetic programme. These studies have already identified genes and signalling pathways that are required for chlamydospore production and should lead to a detailed understanding of this fascinating developmental process.

Chlamydospore Specific Proteins of Candida albicans

“…Chlamydospores are a relatively unusual morphological form that facilitates survival of C. albicans under extreme micro environments by significantly lowering metabolism; however, they can germinate once conditions become favorable [3,4,6,8,9]. The thick walls could provide protection against the adverse microenvironment; however, not much study is available on the structure and composition of chlamydospore cell walls [9][10][11][12][13][14]. In the present study, a proteomic profile of chlamydospores of C. albicans generated using LC-MS/MS provides insights into the regulation of chlamydospore formation and survival strategies.…”

“…The significance and regulation of chlamydospore formation are not yet fully understood, though Böttcher et al (2016) provides a detailed account of signaling pathways regulating chlamydospore formation in response to different environmental and nutritional factors [1,3,4]. Chlamydospores are a relatively unusual morphological form that facilitates survival of C. albicans under extreme micro environments by significantly lowering metabolism; however, they can germinate once conditions become favorable [3,4,6,8,9]. The thick walls could provide protection against the adverse microenvironment; however, not much study is available on the structure and composition of chlamydospore cell walls [9][10][11][12][13][14].…”

“…Morphophysiological plasticity enables Candida albicans to survive under a variety of extreme microenvironments [1][2][3][4][5][6][7][8][9][10][11]. It exists in the form of yeast, hyphae, pseudohyphae, chlamydospore, white/opaque cells, according to the microenvironment [1][2][3][4][5][6][7][8][9][10][11].…”

“…It exists in the form of yeast, hyphae, pseudohyphae, chlamydospore, white/opaque cells, according to the microenvironment [1][2][3][4][5][6][7][8][9][10][11]. Cells in different morphological forms respond differently towards host defense mechanisms, antifungal agents, stress conditions [8].…”

Differential Interaction of the Two Related Fungal SpeciesCandida albicansandCandida dubliniensiswith Human Neutrophils

“…C. dubliniensis was first discovered in 1995 upon genetic characterization and is mainly recovered from oral candidosis of HIV + patients (2). C. dubliniensis is the closest relative of C. albicans and is the only other Candida species able to form true hyphae and chlamydospores (3).…”