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Poumay, Y.

Publications and source records attributed to Poumay, Y..

2 recordsLinked to original sources

Host skin lipids trigger MAT-dependent mating, pathogenic hyphal growth, and parasexual reproduction of Malassezia furfur

The lipophilic yeast genus Malassezia dominates the human skin mycobiome and, while typically commensal, is associated with skin disorders in which hyphal cells are frequently observed. However, the mechanisms underlying hyphal differentiation and its contribution to pathogenesis remain poorly understood. Here, we show that hyphal growth in Malassezia furfur requires a complete mating-type system and is promoted by noncanonical reproductive interactions. Interspecific mating generates stable diploid hybrids with evidence of recombination, whereas intraspecific mating produces cell-fusion products that undergo recombination and haploidization, consistent with a parasexual cycle. Functional analyses reveal that the pheromone/receptor (P/R) locus governs cell recognition and fusion, while the homeodomain (HD) locus is required for hyphal development despite having lost canonical mating-type determination. Leveraging in vitro and in vivo skin models, we show that hyphal cells invade the epidermis more efficiently and elicit stronger inflammatory responses than yeast cells. Together, these findings link parasexual-like reproduction, mating-type loci function, and morphogenesis in Malassezia to pathogenic interactions with the host.

microbiology↗

Characterization of Reconstructed Human Epidermis in a Chemically-defined, Animal Origin-free Cell Culture System

The Reconstructed Human Epidermis (RHE) model derived from epidermal keratinocytes offers an ethical and scientifically valid alternative to animal experimentation, particularly in cutaneous toxicology and dermatological research, where elimination of animal cruelty is of paramount importance. Moreover, safer cell- and tissue-based cutaneous therapies are also possible, where the removal of animal-originated products from the RHE culture media lessens the risk of adverse clinical events. Thus, we compared chemically-define animal origin-free (cdAOF) supplements and the historically utilized supplement (HKGS), which contains growth factors and bovine pituitary extract. Herein we present the first extended characterization of RHE using cdAOF culture systems with newborn, adult, and immortalized N/TERT keratinocytes. Culture of RHE in the cdAOF media produced histological features that were nearly identical to that produced using HKGS, with the exception that the basal keratinocytes were less cylindrical, and with some immunolocalization of involucrin in the basal layer. Additionally, increased mRNA expression of several inflammatory-proliferative markers was observed in the cdAOF RHEs as well. Importantly, in RHEs cultured in cdAOF media, expression and immunolocalization of other expected markers of keratinization, as well as monitoring of barrier function revealed results equal or close to those observed in RHE cultured in HKGS.

cell biology↗