Dataset Information

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

ABSTRACT: Maintenance 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 (MAPK) 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 coordinating chemotropic growth toward an extracellular signal, and then mediating cell fusion. Canonical MAPK 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, but it is unclear what targets ADV-1. We did RNA sequencing on ?adv-1, ?pp-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 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 ?pp-1 mutant and partially suppress the phenotype of the ?mak-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.

SUBMITTER: Fischer MS

PROVIDER: S-EPMC5972422 | biostudies-literature | 2018 Jun

REPOSITORIES: biostudies-literature

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Publications

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

Fischer Monika S MS Wu Vincent W VW Lee Ji E JE O'Malley Ronan C RC Glass N Louise NL

Genetics 20180420 2

Maintenance 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 (MAPK) 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 c ...[more]

PMID: 29678830

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Project description:Cell fusion in genetically identical Neurospora crassa germlings and in hyphae is a highly regulated process involving the activation of a conserved MAP kinase cascade that includes NRC-1, MEK-2 and MAK-2. During chemotrophic growth in germlings, the MAP kinase cascade members localize to conidial anastomosis tube (CAT) tips every ∼8 minutes, perfectly out of phase with another protein that is recruited to the tip: SOFT, a recently identified scaffold for the MAK-1 MAP kinase pathway in Sordaria macrospora. How the MAK-2 oscillation process is initiated, maintained and what proteins regulate the MAP kinase cascade is currently unclear. A global phosphoproteomics approach using an allele of mak-2 (mak-2Q100G) that can be specifically inhibited by the ATP analog 1NM-PP1 was utilized to identify MAK-2 kinase targets in germlings that were potentially involved in this process. One such putative target was HAM-5, a protein of unknown biochemical function. Previously, Δham-5 mutants were shown to be deficient for hyphal fusion. Here we show that HAM-5-GFP co-localized with NRC-1, MEK-2 and MAK-2 and oscillated with identical dynamics from the cytoplasm to CAT tips during chemotropic interactions. In the Δmak-2 strain, HAM-5-GFP localized to punctate complexes that did not oscillate, but still localized to the germling tip, suggesting that MAK-2 activity influences HAM-5 function/localization. However, MAK-2-GFP showed cytoplasmic and nuclear localization in a Δham-5 strain and did not localize to puncta. Via co-immunoprecipitation experiments, HAM-5 was shown to physically interact with NRC-1, MEK-2 and MAK-2, suggesting that it functions as a scaffold/transport hub for the MAP kinase cascade members for oscillation and chemotropic interactions during germling and hyphal fusion in N. crassa. The identification of HAM-5 as a scaffold-like protein will help to link the activation of MAK-2 cascade to upstream factors and proteins involved in this intriguing process of fungal communication.

Dataset Information

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

Publications

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

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