Journal Article

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, Lee, Ji E, Wu, Vincent W, Glass, N Louise, O’Malley, Ronan C

2018

Overview

Filamentous fungi depend on asexual cell-to-cell communication and cell fusion to establish and maintain an interconnected mycelial colony. In Neurospora crassa, genetically identical asexual spores undergo chemotropic interactions resulting in cell fusion and colony establishment... 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 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 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.

• Publisher: Genetics Society of America
• Subject: Binding sites / Bioinformatics / Biological activity / Cell Communication / Cell fusion / Cell interactions / Cell Wall - metabolism / Cell walls / Cellular stress response / Clonal deletion / Communication / Crosstalk / Deletion mutant / Deoxyribonucleic acid / DNA / DNA sequencing / Fungal Proteins - genetics / Fungal Proteins - metabolism / Fungi / Gene expression / Gene Expression Regulation, Fungal / Genetics / Genetics & Heredity / Genomes / Genomics / Genotype & phenotype / In vitro methods and tests / Integrity / Investigations / Kinases / MAP kinase / MAP Kinase Signaling System / Neurospora / Neurospora crassa / Neurospora crassa - genetics / Neurospora crassa - metabolism / Phenotypes / Proteins / Purification / Ribonucleic acid / RNA / Saccharomyces cerevisiae / Signal reception / Transcription factors / Transcription Factors - genetics / Transcription Factors - metabolism