NADPH oxidases NOX-1 and NOX-2 require the regulatory subunit NOR-1 to control cell differentiation and growth in Neurospora crassa.
We have proposed that reactive oxygen species (ROS) play essential roles in cell differentiation. Enzymes belonging to the NADPH oxidase (NOX) family produce superoxide in a regulated manner. We have identified three distinct NOX subfamilies in the fungal kingdom and have shown that NoxA is required for sexual cell differentiation in Aspergillus nidulans. Here we show that Neurospora crassa NOX-1 elimination results in complete female sterility, decreased asexual development, and reduction of hyphal growth. The lack of NOX-2 did not affect any of these processes but led instead to the production of sexual spores that failed to germinate, even in the presence of exogenous oxidants. The elimination of NOR-1, an ortholog of the mammalian Nox2 regulatory subunit gp67(phox), also caused female sterility, the production of unviable sexual spores, and a decrease in asexual development and hyphal growth. These results indicate that NOR-1 is required for NOX-1 and NOX-2 functions at different developmental stages and establish a link between NOX-generated ROS and the regulation of growth. Indeed, NOX-1 was required for the increased asexual sporulation previously observed in mutants without catalase CAT-3. We also analyzed the function of the penta-EF calcium-binding domain protein PEF-1 in N. crassa. Deletion of pef-1 resulted in increased conidiation but, in contrast to what occurs in Dictyostelium discoideum, the mutation of this peflin did not suppress the phenotypes caused by the lack of NOX-1. Our results support the role of ROS as critical cell differentiation signals and highlight a novel role for ROS in regulation of fungal growth.
Cano-Domínguez
Nallely
N
Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-242, 04510, Mexico City, D.F., Mexico.
Alvarez-Delfín
Karen
K
Hansberg
Wilhelm
W
Aguirre
Jesús
J
D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology*; D049108:Cell Enlargement; D015966:Gene Expression Regulation, Fungal / Q000235:genetics; D009247:NADH, NADPH Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000074624:NADPH Oxidase 1; D019255:NADPH Oxidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009492:Neurospora crassa / Q000201:enzymology* / Q000235:genetics; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012098:Reproduction / Q000235:genetics
D002135:Calcium-Binding Proteins; C441461:PEF-1 protein, Dictyostelium discoideum; D010750:Phosphoproteins; D021122:Protein Subunits; D017382:Reactive Oxygen Species; C079789:neutrophil cytosol factor 67K; D009247:NADH, NADPH Oxidoreductases; D000074624:NADPH Oxidase 1; D019255:NADPH Oxidases