E-GEOD-42258 - The transcriptomic signature of RacA activation and inactivation provides new insights into the morphogenetic network of Aspergillus niger
Released on 25 August 2013, last updated on 2 June 2014
RacA is the main Rho GTPase in Aspergillus niger regulating polarity maintenance via controlling actin dynamics. We have previously shown that both deletion and dominant activation of RacA (RacG18V) provoke an actin localization defect and thereby loss of polarized tip extension. This loss of apical dominance results in frequent dichotomous branching in the racA deletion strain and an apolar growing phenotype for RacG18V. In the current study we investigated the transcriptomics and physiological consequences of these morphological changes and compared the data with our previously established morphogenetic network model for the dichotomous branching mutant ramosa-1. This integrated approach revealed that polar tip growth is most likely orchestrated by the concerted activities of phospholipid signaling, sphingolipid signaling, TORC2 signaling, calcium signaling and CWI signaling pathways. The transcriptomic signatures and the reconstructed network model for all three morphology mutants imply that these pathways become integrated to bring about different physiological adaptations including changes in sterol, zinc and amino acid metabolism and changes in ion transport and protein trafficking. We furthermore followed that fate of exocytotic (SncA) and endocytotic (AbpA, SlaB) markers in the dichotomous branching racA deletion mutant, and provide data demonstrating that hyperbranching does not per se result in increased protein secretion. This data set consists of 14 samples in total and covers the genome-wide transcriptional responses of Aspergillus niger towards deletion of racA and expression of a dominant active racA allele (G18V). The genome-wide transcriptional effect of deleting racA was monitored by comparison with the A. niger wild type. For both, the racA deletion mutant and the wild type, samples consist of biological triplicates (6 in total). The genome-wide transcriptional effect of expressing the dominant active racA mutant allele was monitored by sampling 2 and 4 hours after induction with maltose. For comparison, the racA wild type allele was induced and expressed similarly and samples were taken at corresponding time points. The experimental setup for the dominant active racA expression consisted of biological triplicates (8 in total).
transcription profiling by array
Benjamin M. Nitsche <email@example.com>, Arthur F Ram, Benjamin M Nitsche, Mark Arentshorst, Min J Kwon, Thomas R Jørgensen, Vera Meyer