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Eukaryotic Cell, August 2008, p. 1352-1361, Vol. 7, No. 8
1535-9778/08/$08.00+0     doi:10.1128/EC.00137-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

NADPH Oxidases NOX-1 and NOX-2 Require the Regulatory Subunit NOR-1 To Control Cell Differentiation and Growth in Neurospora crassa ^,

Nallely Cano-Domínguez,¹ Karen Álvarez-Delfín,^1, Wilhelm Hansberg,² and Jesús Aguirre^1*

Departamentos de Genética Molecular,¹ Bioquímica, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-242, 04510, Mexico City, D.F., Mexico²

Received 17 April 2008/ Accepted 12 June 2008

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.

Published ahead of print on 20 June 2008.

Supplemental material for this article may be found at http://ec.asm.org/.

Present address: 221 Biomedical Research Facility, Department of Biological Science, Florida State University, Tallahassee, FL 32306.