1
|
Moreau J, Noël T, Point K, Tewes F, Deroche L, Clarhaut J, Fitton-Ouhabi V, Perraud E, Marchand S, Buyck JM, Brunet K. Pan-azole-resistant Meyerozyma guilliermondii clonal isolates harbouring a double F126L and L505F mutation in Erg11. Mycoses 2024; 67:e13704. [PMID: 38429226 DOI: 10.1111/myc.13704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 01/29/2024] [Accepted: 02/02/2024] [Indexed: 03/03/2024]
Abstract
BACKGROUND Meyerozyma guilliermondii is a yeast species responsible for invasive fungal infections. It has high minimum inhibitory concentrations (MICs) to echinocandins, the first-line treatment of candidemia. In this context, azole antifungal agents are frequently used. However, in recent years, a number of azole-resistant strains have been described. Their mechanisms of resistance are currently poorly studied. OBJECTIVE The aim of this study was consequently to understand the mechanisms of azole resistance in several clinical isolates of M. guilliermondii. METHODS Ten isolates of M. guilliermondii and the ATCC 6260 reference strain were studied. MICs of azoles were determined first. Whole genome sequencing of the isolates was then carried out and the mutations identified in ERG11 were expressed in a CTG clade yeast model (C. lusitaniae). RNA expression of ERG11, MDR1 and CDR1 was evaluated by quantitative PCR. A phylogenic analysis was developed and performed on M. guilliermondii isolates. Lastly, in vitro experiments on fitness cost and virulence were carried out. RESULTS Of the ten isolates tested, three showed pan-azole resistance. A combination of F126L and L505F mutations in Erg11 was highlighted in these three isolates. Interestingly, a combination of these two mutations was necessary to confer azole resistance. An overexpression of the Cdr1 efflux pump was also evidenced in one strain. Moreover, the three pan-azole-resistant isolates were shown to be genetically related and not associated with a fitness cost or a lower virulence, suggesting a possible clonal transmission. CONCLUSION In conclusion, this study identified an original combination of ERG11 mutations responsible for pan-azole-resistance in M. guilliermondii. Moreover, we proposed a new MLST analysis for M. guilliermondii that identified possible clonal transmission of pan-azole-resistant strains. Future studies are needed to investigate the distribution of this clone in hospital environment and should lead to the reconsideration of the treatment for this species.
Collapse
Affiliation(s)
- Jérémy Moreau
- Université de Poitiers, INSERM U1070 PHAR2, Poitiers, France
| | - Thierry Noël
- Université de Bordeaux, CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
| | - Kévin Point
- Université de Poitiers, INSERM U1070 PHAR2, Poitiers, France
| | - Frédéric Tewes
- Université de Poitiers, INSERM U1070 PHAR2, Poitiers, France
| | - Luc Deroche
- CHU de Poitiers, Service de Virologie, Poitiers, France
| | - Jonathan Clarhaut
- Université de Poitiers, INSERM U1070 PHAR2, Poitiers, France
- CHU de Poitiers, Service de Toxicologie-Pharmacocinétique, Poitiers, France
| | - Valérie Fitton-Ouhabi
- Université de Bordeaux, CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
| | - Estelle Perraud
- CHU de Poitiers, Service de Parasitologie et Mycologie Médicale, Poitiers, France
| | - Sandrine Marchand
- Université de Poitiers, INSERM U1070 PHAR2, Poitiers, France
- CHU de Poitiers, Service de Toxicologie-Pharmacocinétique, Poitiers, France
| | - Julien M Buyck
- Université de Poitiers, INSERM U1070 PHAR2, Poitiers, France
| | - Kévin Brunet
- Université de Poitiers, INSERM U1070 PHAR2, Poitiers, France
- CHU de Poitiers, Service de Parasitologie et Mycologie Médicale, Poitiers, France
| |
Collapse
|
2
|
Sabra A, Biteau N, Dupuy J, Klopp C, Noël T, Dementhon K. Mediator Subunit Med15 Regulates Cell Morphology and Mating in Candida lusitaniae. J Fungi (Basel) 2023; 9:333. [PMID: 36983501 PMCID: PMC10053558 DOI: 10.3390/jof9030333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 02/26/2023] [Accepted: 02/27/2023] [Indexed: 03/12/2023] Open
Abstract
Candida lusitaniae is an emerging opportunistic pathogenic yeast capable of shifting from yeast to pseudohyphae form, and it is one of the few Candida species with the ability to reproduce sexually. In this study, we showed that a dpp3Δ mutant, inactivated for a putative pyrophosphatase, is impaired in cell separation, pseudohyphal growth and mating. The defective phenotypes were not restored after the reconstruction of a wild-type DPP3 locus, reinforcing the hypothesis of the presence of an additional mutation that we suspected in our previous study. Genetic crosses and genome sequencing identified an additional mutation in MED15, encoding a subunit of the mediator complex that functions as a general transcriptional co-activator in Eukaryotes. We confirmed that inactivation of MED15 was responsible for the defective phenotypes by rescuing the dpp3Δ mutant with a wild-type copy of MED15 and constructing a med15Δ knockout mutant that mimics the phenotypes of dpp3Δ in vitro. Proteomic analyses revealed the biological processes under the control of Med15 and involved in hyphal growth, cell separation and mating. This is the first description of the functions of MED15 in the regulation of hyphal growth, cell separation and mating, and the pathways involved in C. lusitaniae.
Collapse
|
3
|
Accoceberry I, Couzigou C, Fitton-Ouhabi V, Biteau N, Noël T. Challenging SNP impact on caspofungin resistance by full-length FKS1 allele replacement in Candida lusitaniae. J Antimicrob Chemother 2020; 74:618-624. [PMID: 30517635 DOI: 10.1093/jac/dky475] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 09/27/2018] [Accepted: 10/19/2018] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES A strain of the opportunistic pathogenic yeast Candida lusitaniae was genetically engineered for full-length replacement of the FKS1 gene encoding the target of echinocandin antifungals in order to assess the impact of FKS mutations on echinocandin resistance and reduced echinocandin susceptibility (RES). METHODS FKS1 allelic exchange was achieved by transforming C. lusitaniae with two DNA fragments covering the entire FKS1 ORF. Both fragments overlap a 40 bp region where SNPs or small indels of interest were inserted. To target integration at the FKS1 locus, each DNA fragment was fused with split auxotrophic markers of which complementary truncated parts were previously inserted into the chromosomal regions flanking FKS1, allowing selection on minimal medium. RESULTS Three SNPs described in the FKS1 hotspot (HS) regions HS1 or HS2 of clinical isolates of Candida albicans were expressed at an equivalent position in C. lusitaniae and were confirmed to confer either reduced susceptibility (F641V) or full resistance (S645P and R1361G) to caspofungin. The F659 deletion reported in an FKS2 allele of Candida glabrata and the naturally occurring P660A substitution in FKS1 of Candida parapsilosis were shown to confer a 256-fold and 6-fold increase in caspofungin MIC, respectively, when introduced into an FKS1 allele of C. lusitaniae. CONCLUSIONS We have successfully developed a C. lusitaniae strain for the expression of full-length FKS1 alleles harbouring known mutations contributing to reduced susceptibility or resistance to caspofungin, thus opening the way for the screening of other FKS1/FKS2 mutations potentially involved in RES.
Collapse
Affiliation(s)
- Isabelle Accoceberry
- Univ. Bordeaux, CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France.,Univ. Bordeaux, CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, CHU Bordeaux, Bordeaux, France
| | - Célia Couzigou
- Univ. Bordeaux, CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France.,Univ. Bordeaux, CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, CHU Bordeaux, Bordeaux, France
| | - Valérie Fitton-Ouhabi
- Univ. Bordeaux, CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
| | - Nicolas Biteau
- Univ. Bordeaux, CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
| | - Thierry Noël
- Univ. Bordeaux, CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, Bordeaux, France
| |
Collapse
|
4
|
Accoceberry I, Rougeron A, Biteau N, Chevrel P, Fitton-Ouhabi V, Noël T. A CTG Clade Candida Yeast Genetically Engineered for the Genotype-Phenotype Characterization of Azole Antifungal Resistance in Human-Pathogenic Yeasts. Antimicrob Agents Chemother 2018; 62:e01483-17. [PMID: 29038279 DOI: 10.1128/AAC.01483-17] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 10/12/2017] [Indexed: 11/20/2022] Open
Abstract
A strain of the opportunistic pathogenic yeast Candida lusitaniae was genetically modified for use as a cellular model for assessing by allele replacement the impact of lanosterol C14α-demethylase ERG11 mutations on azole resistance. Candida lusitaniae was chosen because it is susceptible to azole antifungals, it belongs to the CTG clade of yeast, which includes most of the Candida species pathogenic for humans, and it is haploid and easily amenable to genetic transformation and molecular modeling. In this work, allelic replacement is targeted at the ERG11 locus by the reconstitution of a functional auxotrophic marker in the 3' intergenic region of ERG11 Homologous and heterologous ERG11 alleles are expressed from the resident ERG11 promoter of C. lusitaniae, allowing accurate comparison of the phenotypic change in azole susceptibility. As a proof of concept, we successfully expressed in C. lusitaniae different ERG11 alleles, either bearing or not bearing mutations retrieved from a clinical context, from two phylogenetically distant yeasts, C. albicans and Kluyveromyces marxianusCandida lusitaniae constitutes a high-fidelity expression system, giving specific Erg11p-dependent fluconazole MICs very close to those observed with the ERG11 donor strain. This work led us to characterize the phenotypic effect of two kinds of mutation: mutation conferring decreased fluconazole susceptibility in a species-specific manner and mutation conferring fluconazole resistance in several yeast species. In particular, a missense mutation affecting amino acid K143 of Erg11p in Candida species, and the equivalent position K151 in K. marxianus, plays a critical role in fluconazole resistance.
Collapse
|
5
|
Quilès F, Accoceberry I, Couzigou C, Francius G, Noël T, El-Kirat-Chatel S. AFM combined to ATR-FTIR reveals Candida cell wall changes under caspofungin treatment. Nanoscale 2017; 9:13731-13738. [PMID: 28884772 DOI: 10.1039/c7nr02170d] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Fungal pathogens from Candida genus are responsible for severe life-threatening infections and the antifungal arsenal is still limited. Caspofungin, an antifungal drug used for human therapy, acts as a blocking agent of the cell wall synthesis by inhibiting the β-1,3-glucan-synthase encoded by FKS genes. Despite its efficiency, the number of genetic mutants that are resistant to caspofungin is increasing. An important challenge to improve antifungal therapy is to understand cellular phenomenon that are associated with drug resistance. Here we used atomic force microscopy (AFM) combined to Fourier transform infrared spectroscopy in attenuated total reflection mode (ATR-FTIR) to decipher the effect of low and high drug concentration on the morphology, mechanics and cell wall composition of two Candida strains, one susceptible and one resistant to caspofungin. Our results confirm that caspofungin induces a dramatic cell wall remodelling via activation of stress responses, even at high drug concentration. Additionally, we highlighted unexpected changes related to drug resistance, suggesting that caspofungin resistance associated with FKS gene mutations comes from a combination of effects: (i) an overall remodelling of yeast cell wall composition; and (ii) cell wall stiffening through chitin synthesis. This work demonstrates that AFM combined to ATR-FTIR is a valuable approach to understand at the molecular scale the biological mechanisms associated with drug resistance.
Collapse
Affiliation(s)
- Fabienne Quilès
- CNRS, Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, LCPME, UMR 7564, Villers-lès-Nancy, F-54600, France.
| | | | | | | | | | | |
Collapse
|
6
|
Gabriel F, Accoceberry I, Bessoule JJ, Salin B, Lucas-Guérin M, Manon S, Dementhon K, Noël T. A Fox2-dependent fatty acid ß-oxidation pathway coexists both in peroxisomes and mitochondria of the ascomycete yeast Candida lusitaniae. PLoS One 2014; 9:e114531. [PMID: 25486052 PMCID: PMC4259357 DOI: 10.1371/journal.pone.0114531] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 11/10/2014] [Indexed: 01/24/2023] Open
Abstract
It is generally admitted that the ascomycete yeasts of the subphylum Saccharomycotina possess a single fatty acid ß-oxidation pathway located exclusively in peroxisomes, and that they lost mitochondrial ß-oxidation early during evolution. In this work, we showed that mutants of the opportunistic pathogenic yeast Candida lusitaniae which lack the multifunctional enzyme Fox2p, a key enzyme of the ß-oxidation pathway, were still able to grow on fatty acids as the sole carbon source, suggesting that C. lusitaniae harbored an alternative pathway for fatty acid catabolism. By assaying 14Cα-palmitoyl-CoA consumption, we demonstrated that fatty acid catabolism takes place in both peroxisomal and mitochondrial subcellular fractions. We then observed that a fox2Δ null mutant was unable to catabolize fatty acids in the mitochondrial fraction, thus indicating that the mitochondrial pathway was Fox2p-dependent. This finding was confirmed by the immunodetection of Fox2p in protein extracts obtained from purified peroxisomal and mitochondrial fractions. Finally, immunoelectron microscopy provided evidence that Fox2p was localized in both peroxisomes and mitochondria. This work constitutes the first demonstration of the existence of a Fox2p-dependent mitochondrial β-oxidation pathway in an ascomycetous yeast, C. lusitaniae. It also points to the existence of an alternative fatty acid catabolism pathway, probably located in peroxisomes, and functioning in a Fox2p-independent manner.
Collapse
Affiliation(s)
- Frédéric Gabriel
- Univ. Bordeaux, Microbiologie Fondamentale et Pathogénicité, UMR 5234, F-33000 Bordeaux, France
- CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, F-33000 Bordeaux, France
| | - Isabelle Accoceberry
- Univ. Bordeaux, Microbiologie Fondamentale et Pathogénicité, UMR 5234, F-33000 Bordeaux, France
- CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, F-33000 Bordeaux, France
| | - Jean-Jacques Bessoule
- Univ. Bordeaux, Laboratoire de Biogenèse Membranaire, UMR 5200, F-33000 Bordeaux, France
- CNRS, Laboratoire de Biogenèse Membranaire, UMR 5200, F-33000 Bordeaux, France
| | - Bénédicte Salin
- Univ. Bordeaux, Institut de Biochimie et Génétique Cellulaires, UMR 5095, F-33000 Bordeaux, France
- CNRS, Institut de Biochimie et Génétique Cellulaires, UMR 5095, F-33000 Bordeaux, France
| | - Marine Lucas-Guérin
- Univ. Bordeaux, Microbiologie Fondamentale et Pathogénicité, UMR 5234, F-33000 Bordeaux, France
- CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, F-33000 Bordeaux, France
| | - Stephen Manon
- Univ. Bordeaux, Institut de Biochimie et Génétique Cellulaires, UMR 5095, F-33000 Bordeaux, France
- CNRS, Institut de Biochimie et Génétique Cellulaires, UMR 5095, F-33000 Bordeaux, France
| | - Karine Dementhon
- Univ. Bordeaux, Microbiologie Fondamentale et Pathogénicité, UMR 5234, F-33000 Bordeaux, France
- CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, F-33000 Bordeaux, France
| | - Thierry Noël
- Univ. Bordeaux, Microbiologie Fondamentale et Pathogénicité, UMR 5234, F-33000 Bordeaux, France
- CNRS, Microbiologie Fondamentale et Pathogénicité, UMR 5234, F-33000 Bordeaux, France
| |
Collapse
|
7
|
Abstract
Candida species are the most common causes of fungal infection. Approximately 90% of infections are caused by five species: Candida albicans, Candida glabrata, Candida tropicalis, Candida parapsilosis, and Candida krusei. Three (C. albicans, C. tropicalis, and C. parapsilosis) belong to the CTG clade, in which the CTG codon is translated as serine and not leucine. C. albicans remains the most commonly isolated but is decreasing relative to the other species. The increasing incidence of C. glabrata is related to its reduced susceptibility to azole drugs. Genome analysis suggests that virulence in the CTG clade is associated with expansion of gene families, particularly of cell wall genes. Similar independent processes took place in the C. glabrata species group. Gene loss and expansion in an ancestor of C. glabrata may have resulted in preadaptations that enabled pathogenicity.
Collapse
Affiliation(s)
- Siobhán A Turner
- School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Geraldine Butler
- School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland
| |
Collapse
|
8
|
Gabriel F, Sabra A, El-Kirat-Chatel S, Pujol S, Fitton-Ouhabi V, Brèthes D, Dementhon K, Accoceberry I, Noël T. Deletion of the uracil permease gene confers cross-resistance to 5-fluorouracil and azoles in Candida lusitaniae and highlights antagonistic interaction between fluorinated nucleotides and fluconazole. Antimicrob Agents Chemother 2014; 58:4476-85. [PMID: 24867971 DOI: 10.1128/AAC.00009-14] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
We characterized two additional membrane transporters (Fur4p and Dal4p) of the nucleobase cation symporter 1 (NCS1) family involved in the uptake transport of pyrimidines and related molecules in the opportunistic pathogenic yeast Candida lusitaniae. Simple and multiple null mutants were constructed by gene deletion and genetic crosses. The function of each transporter was characterized by supplementation experiments, and the kinetic parameters of the uptake transport of uracil were measured using radiolabeled substrate. Fur4p specifically transports uracil and 5-fluorouracil. Dal4p is very close to Fur4p and transports allantoin (glyoxyldiureide). Deletion of the FUR4 gene confers resistance to 5-fluorouracil as well as cross-resistance to triazoles and imidazole antifungals when they are used simultaneously with 5-fluorouracil. However, the nucleobase transporters are not involved in azole uptake. Only fluorinated pyrimidines, not pyrimidines themselves, are able to promote cross-resistance to azoles by both the salvage and the de novo pathway of pyrimidine synthesis. A reinterpretation of the data previously obtained led us to show that subinhibitory doses of 5-fluorocytosine, 5-fluorouracil, and 5-fluorouridine also were able to trigger resistance to fluconazole in susceptible wild-type strains of C. lusitaniae and of different Candida species. Our results suggest that intracellular fluorinated nucleotides play a key role in azole resistance, either by preventing azoles from targeting the lanosterol 14-alpha-demethylase or its catalytic site or by acting as a molecular switch for the triggering of efflux transport.
Collapse
|
9
|
Sherwood RK, Scaduto CM, Torres SE, Bennett RJ. Convergent evolution of a fused sexual cycle promotes the haploid lifestyle. Nature 2014; 506:387-390. [PMID: 24390351 PMCID: PMC4051440 DOI: 10.1038/nature12891] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Accepted: 11/18/2013] [Indexed: 12/29/2022]
Affiliation(s)
- Racquel Kim Sherwood
- Department of Microbiology and Immunology, Brown University, 171 Meeting St, Providence, RI, 02912
| | - Christine M Scaduto
- Department of Microbiology and Immunology, Brown University, 171 Meeting St, Providence, RI, 02912
| | - Sandra E Torres
- Department of Microbiology and Immunology, Brown University, 171 Meeting St, Providence, RI, 02912
| | - Richard J Bennett
- Department of Microbiology and Immunology, Brown University, 171 Meeting St, Providence, RI, 02912
| |
Collapse
|
10
|
Lan Thanh Bien T, Tsuji S, Tanaka K, Takenaka S, Yoshida KI. Secretion of heterologous thermostable cellulases in Bacillus subtilis. J GEN APPL MICROBIOL 2014; 60:175-82. [DOI: 10.2323/jgam.60.175] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
11
|
Sabra A, Bessoule JJ, Atanasova-Penichon V, Noël T, Dementhon K. Host-pathogen interaction and signaling molecule secretion are modified in the dpp3 knockout mutant of Candida lusitaniae. Infect Immun 2014; 82:413-22. [PMID: 24191303 DOI: 10.1128/IAI.01263-13] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Candida lusitaniae is an emerging opportunistic yeast and an attractive model to discover new virulence factors in Candida species by reverse genetics. Our goal was to create a dpp3Δ knockout mutant and to characterize the effects of this gene inactivation on yeast in vitro and in vivo interaction with the host. The secretion of two signaling molecules in Candida species, phenethyl alcohol (PEA) and tyrosol, but not of farnesol was surprisingly altered in the dpp3Δ knockout mutant. NO and reactive oxygen species (ROS) production as well as tumor necrosis factor alpha (TNF-α) and interleukin 10 (IL-10) secretion were also modified in macrophages infected with this mutant. Interestingly, we found that the wild-type (WT) strain induced an increase in IL-10 secretion by zymosan-activated macrophages without the need for physical contact, whereas the dpp3Δ knockout mutant lost this ability. We further showed a striking role of PEA and tyrosol in this modulation. Last, the DPP3 gene was found to be an essential contributor to virulence in mice models, leading to an increase in TNF-α secretion and brain colonization. Although reinsertion of a WT DPP3 copy in the dpp3Δ knockout mutant was not sufficient to restore the WT phenotypes in vitro, it allowed a restoration of those observed in vivo. These data support the hypothesis that some of the phenotypes observed following DPP3 gene inactivation may be directly dependent on DPP3, while others may be the indirect consequence of another genetic modification that systematically arises when the DPP3 gene is inactivated.
Collapse
|