0679 - Cell-to-cell communication is regulated by a network of MAP Kinase pathways and transcription factors in the filamentous fungus, Neurospora crassa

ABSTRACTMaintenance of cell integrity and cell-to-cell communication are fundamental biological processes. Filamentous fungi, such as Neurospora crassa, depend on communication to locate compatible cells, coordinate cell fusion, and establish a robust hyphal network. Two MAP-Kinase pathways are essential for communication and cell fusion in N. crassa; the Cell Wall Integrity/MAK-1 pathway and the MAK-2 (signal response) pathway. Previous studies have demonstrated several points of cross talk between the MAK-1 and MAK-2 pathways, which is likely necessary for oordinating chemotropic growth toward an extracellular signal, and then mediating cell fusion. Canonical MAP-Kinase pathways begin with signal reception and end with a transcriptional response. Two transcription factors, ADV-1 and PP-1, are essential for communication and cell fusion. PP-1 is the conserved target of MAK-2, while it is unclear what targets ADV-1. We did RNAseq on Δadv-1, Δpp-1, and wild-type cells and found that ADV-1 and PP-1 have a shared regulon including many genes required for communication, cell fusion, growth, development, and stress response. We identified ADV-1 and PP-1 binding sites across the genome by adapting the in vitro method of DNA-Affinity Purification sequencing (DAP-seq) for N. crassa. To elucidate the regulatory network, we misexpressed each transcription factor in each upstream MAPK deletion mutant. Misexpression of adv-1 was sufficient to fully suppress the phenotype of the Δpp-1 mutant and partially suppress the phenotype of the Δmak-1 mutant. Collectively, our data demonstrate that the MAK-1-ADV-1 and MAK-2- PP-1 pathways form a tight regulatory network that maintains cell integrity and mediates communication and cell fusion.

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Regulation of Cell-to-Cell Communication and Cell Wall Integrity by a Network of MAP Kinase Pathways and Transcription Factors in Neurospora crassa

Genetics ◽

10.1534/genetics.118.300904 ◽

2018 ◽

Vol 209 (2) ◽

pp. 489-506 ◽

Cited By ~ 15

Author(s):

Monika S. Fischer ◽

Vincent W. Wu ◽

Ji E. Lee ◽

Ronan C. O’Malley ◽

N. Louise Glass

Keyword(s):

Cell Wall ◽

Transcription Factors ◽

Map Kinase ◽

Neurospora Crassa ◽

Cell Communication ◽

Cell Wall Integrity ◽

Map Kinase Pathways

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Role of a Mitogen-Activated Protein Kinase Pathway during Conidial Germination and Hyphal Fusion in Neurospora crassa

Eukaryotic Cell ◽

10.1128/ec.3.2.348-358.2004 ◽

2004 ◽

Vol 3 (2) ◽

pp. 348-358 ◽

Cited By ~ 124

Author(s):

Amita Pandey ◽

M. Gabriela Roca ◽

Nick D. Read ◽

N. Louise Glass

Keyword(s):

Map Kinase ◽

Neurospora Crassa ◽

Conidial Germination ◽

Colony Development ◽

Phenotypic Traits ◽

Hyphal Fusion ◽

Mitogen Activated Protein ◽

Map Kinase Pathways ◽

Map Kinase Kinase Kinase ◽

Map Kinase Kinase

ABSTRACT Mitogen-activated protein (MAP) kinase signaling pathways are ubiquitous and evolutionarily conserved in eukaryotic organisms. MAP kinase pathways are composed of a MAP kinase, a MAP kinase kinase, and a MAP kinase kinase kinase; activation is regulated by sequential phosphorylation. Components of three MAP kinase pathways have been identified by genome sequence analysis in the filamentous fungus Neurospora crassa. One of the predicted MAP kinases in N. crassa, MAK-2, shows similarity to Fus3p and Kss1p of Saccharomyces cerevisiae, which are involved in sexual reproduction and filamentation, respectively. In this study, we show that an N. crassa mutant disrupted in mak-2 exhibits a pleiotropic phenotype: derepressed conidiation, shortened aerial hyphae, lack of vegetative hyphal fusion, female sterility, and autonomous ascospore lethality. We assessed the phosphorylation of MAK-2 during conidial germination and early colony development. Peak levels of MAK-2 phosphorylation were most closely associated with germ tube elongation, branching, and hyphal fusion events between conidial germlings. A MAP kinase kinase kinase (NRC-1) is the predicted product of N. crassa nrc-1 locus and is a homologue of STE11 in S. cerevisiae. An nrc-1 mutant shares many of the same phenotypic traits as the mak-2 mutant and, in particular, is a hyphal fusion mutant. We show that MAK-2 phosphorylation during early colony development is dependent upon the presence of NRC-1 and postulate that phosphorylation of MAK-2 is required for hyphal fusion events that occur during conidial germination.

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Coordinated Regulation of Protoperithecium Development by MAP Kinases MAK-1 and MAK-2 in Neurospora crassa

Frontiers in Microbiology ◽

10.3389/fmicb.2021.769615 ◽

2021 ◽

Vol 12 ◽

Author(s):

Nan Lan ◽

Shuting Ye ◽

Chengcheng Hu ◽

Zhiling Chen ◽

Jun Huang ◽

...

Keyword(s):

Map Kinase ◽

Neurospora Crassa ◽

Cross Talk ◽

Sexual Development ◽

Map Kinases ◽

Deletion Mutants ◽

Transcriptional Responses ◽

Map Kinase Pathway ◽

Map Kinase Pathways ◽

Kinase Pathway

Mitogen-activated protein (MAP) kinase pathways function as signaling hubs that are integral for many essential cellular processes, including sexual development. The molecular mechanisms and cross-talk between PR and CWI MAP kinase pathways have been extensively studied during asexual development. However, if these can be extended to sexual development remains elusive. By analyzing genome-wide transcriptional responses to deletion of each of two MAP kinase coding genes mak-2 (PR-MAP kinase pathway) and mak-1 (CWI-MAP kinase pathway) in Neurospora crassa during protoperithecium formation, 430 genes co-regulated by the MAK-1 and MAK-2 proteins were found, functionally enriched at integral components of membrane and oxidoreductase. These genes include 13 functionally known genes participating in sexual development (app, poi-2, stk-17, fsd-1, vsd-8, and NCU03863) and melanin synthesis (per-1, pkh-1, pkh-2, mld-1, scy-1, trn-2, and trn-1), as well as a set of functionally unknown genes. Phenotypic analysis of deletion mutants for the functionally unknown genes revealed that 12 genes were essential for female fertility. Among them, single-gene deletion mutants for NCU07743 (named as pfd-1), NCU02250 (oli), and NCU05948 (named as pfd-2) displayed similar protoperithecium development defects as the Δmak-1 and Δmak-2 mutants, failing to form protoperithecium. Western blotting analysis showed that both phosphorylated and total MAK-1 proteins were virtually abolished in the Δnrc-1, Δmek-2, and Δmak-2 mutants, suggesting that the posttranscriptional regulation of MAK-1 is dependent on the PR-MAP kinase pathway during the protoperithecium development. Taken together, this study revealed the regulatory roles and cross-talk between PR and CWI-MAP kinase pathways during protoperithecium development.

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