title: The virulence of the opportunistic fungal pathogen Aspergillus fumigatus requires cooperation between the endoplasmic reticulum-associated degradation pathway (ERAD) and the unfolded protein response (UPR).
abstract: The filamentous fungal pathogen Aspergillus fumigatus secretes hydrolytic enzymes to acquire nutrients from host tissues. The production of these enzymes exerts stress on the endoplasmic reticulum (ER), which is alleviated by two stress responses: the unfolded protein response (UPR), which adjusts the protein folding capacity of the ER, and ER-associated degradation (ERAD), which disposes of proteins that fail to fold correctly. In this study, we examined the contribution of these integrated pathways to the growth and virulence of A. fumigatus, focusing on the ERAD protein DerA and the master regulator of the UPR, HacA. A ΔderA mutant grew normally and showed no increase in sensitivity to ER stress. However, expression of the UPR target gene bipA was constitutively elevated in this strain, suggesting that the UPR was compensating for the absence of DerA function. To test this, the UPR was disrupted by deleting the hacA gene. The combined loss of derA and hacA caused a more severe reduction in hyphal growth, antifungal drug resistance and protease secretion than the loss of either gene alone, suggesting that DerA and HacA cooperate to support these functions.  Moreover, the ΔderA/ΔhacA mutant was avirulent in a mouse model of invasive aspergillosis, which contrasted the wild type virulence of ΔderA and the reduced virulence of the ΔhacA mutant. Taken together, these data demonstrate that DerA cooperates with the UPR to support the expression of virulence-related attributes of A. fumigatus.
authors.affiliation: Department of Pathology & Laboratory Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
authors.forename: Daryl L
authors.initials: DL
authors.lastname: Richie
authors.forename: Xizhi
authors.initials: X
authors.lastname: Feng
authors.forename: Lukas
authors.initials: L
authors.lastname: Hartl
authors.forename: Vishukumar
authors.initials: V
authors.lastname: Aimanianda
authors.forename: Karthik
authors.initials: K
authors.lastname: Krishnan
authors.forename: Margaret V
authors.initials: MV
authors.lastname: Powers-Fletcher
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Watson
authors.forename: Amit K
authors.initials: AK
authors.lastname: Galande
authors.forename: Stephanie M
authors.initials: SM
authors.lastname: White
authors.forename: Taryn
authors.initials: T
authors.lastname: Willett
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Latgé
authors.forename: Judith C
authors.initials: JC
authors.lastname: Rhodes
authors.forename: David S
authors.initials: DS
authors.lastname: Askew
mesh_terms: D000818:Animals; D021461:Animals, Outbred Strains; D001228:Aspergillosis / Q000382:microbiology*; D001232:Aspergillus fumigatus / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D004721:Endoplasmic Reticulum / Q000235:genetics / Q000378:metabolism*; D005260:Female; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D051379:Mice; D056811:Unfolded Protein Response; D014774:Virulence
chemical_list: D005656:Fungal Proteins