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The transcriptomic signature of RacA activation and inactivation provides new insights into the morphogenetic network of Aspergillus niger.

Kwon MJ, Nitsche BM, Arentshorst M, Jørgensen TR, Ram AF, Meyer V - PLoS ONE (2013)

Bottom Line: In the current study the transcriptomics and physiological consequences of these morphological changes were investigated and compared with the data of the morphogenetic network model for the dichotomous branching mutant ramosa-1.The transcriptomic signatures and the reconstructed network model for all three morphology mutants (ΔracA, Rac(G18V), ramosa-1) 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.Finally, the fate of exocytotic (SncA) and endocytotic (AbpA, SlaB) markers in the dichotomous branching mutant ΔracA was followed, demonstrating that hyperbranching does not per se result in increased protein secretion.

View Article: PubMed Central - PubMed

Affiliation: Leiden University, Institute of Biology Leiden, Department Molecular Microbiology and Biotechnology, Leiden, The Netherlands.

ABSTRACT
RacA is the main Rho GTPase in Aspergillus niger regulating polarity maintenance via controlling actin dynamics. Both deletion and dominant activation of RacA (Rac(G18V)) provoke an actin localization defect and thereby loss of polarized tip extension, resulting in frequent dichotomous branching in the ΔracA strain and an apolar growing phenotype for Rac(G18V). In the current study the transcriptomics and physiological consequences of these morphological changes were investigated and compared with the data of the 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 (ΔracA, Rac(G18V), ramosa-1) 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. Finally, the fate of exocytotic (SncA) and endocytotic (AbpA, SlaB) markers in the dichotomous branching mutant ΔracA was followed, demonstrating that hyperbranching does not per se result in increased protein secretion.

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Related in: MedlinePlus

Venn diagrams of induced (black numbers), repressed (grey numbers) and up- or down-regulated (italics numbers) genes for the PglaA-RacAG18V/PglaA-RacA and ΔracA/N402 comparisons.
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pone-0068946-g006: Venn diagrams of induced (black numbers), repressed (grey numbers) and up- or down-regulated (italics numbers) genes for the PglaA-RacAG18V/PglaA-RacA and ΔracA/N402 comparisons.

Mentions: To identify those genes which only relate to the difference between polar to apolar morphology in PglaA-racAG18V but are independent from time and carbon source, a Venn diagram was constructed (Fig. 6) and the intersection determined representing genes which are differently expressed after both 2 and 4 h in PglaA-racAG18V when compared to the 2 h and 4 h data sets of the PglaA-racA reference strain. Overall, 148 genes showed different expression, 106 of which were up-regulated and 42 of which were down-regulated in PglaA-racAG18V (Table S4). Again, only a small set of genes (about 1% of the A. niger genome) show different expression levels during polar and apolar growth. Table 4 highlights the most interesting genes of this compilation, which could be grouped into several regulatory processes including (i) (phospho)lipid signaling, (ii) calcium signaling, (iii) CWI signaling and (iv) nitrogen signaling. In addition, metabolic processes including primary metabolism (amino acid biosynthesis) and secondary metabolism (polyketide synthesis, non-ribosomal peptide synthesis) were affected as well.


The transcriptomic signature of RacA activation and inactivation provides new insights into the morphogenetic network of Aspergillus niger.

Kwon MJ, Nitsche BM, Arentshorst M, Jørgensen TR, Ram AF, Meyer V - PLoS ONE (2013)

Venn diagrams of induced (black numbers), repressed (grey numbers) and up- or down-regulated (italics numbers) genes for the PglaA-RacAG18V/PglaA-RacA and ΔracA/N402 comparisons.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3722221&req=5

pone-0068946-g006: Venn diagrams of induced (black numbers), repressed (grey numbers) and up- or down-regulated (italics numbers) genes for the PglaA-RacAG18V/PglaA-RacA and ΔracA/N402 comparisons.
Mentions: To identify those genes which only relate to the difference between polar to apolar morphology in PglaA-racAG18V but are independent from time and carbon source, a Venn diagram was constructed (Fig. 6) and the intersection determined representing genes which are differently expressed after both 2 and 4 h in PglaA-racAG18V when compared to the 2 h and 4 h data sets of the PglaA-racA reference strain. Overall, 148 genes showed different expression, 106 of which were up-regulated and 42 of which were down-regulated in PglaA-racAG18V (Table S4). Again, only a small set of genes (about 1% of the A. niger genome) show different expression levels during polar and apolar growth. Table 4 highlights the most interesting genes of this compilation, which could be grouped into several regulatory processes including (i) (phospho)lipid signaling, (ii) calcium signaling, (iii) CWI signaling and (iv) nitrogen signaling. In addition, metabolic processes including primary metabolism (amino acid biosynthesis) and secondary metabolism (polyketide synthesis, non-ribosomal peptide synthesis) were affected as well.

Bottom Line: In the current study the transcriptomics and physiological consequences of these morphological changes were investigated and compared with the data of the morphogenetic network model for the dichotomous branching mutant ramosa-1.The transcriptomic signatures and the reconstructed network model for all three morphology mutants (ΔracA, Rac(G18V), ramosa-1) 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.Finally, the fate of exocytotic (SncA) and endocytotic (AbpA, SlaB) markers in the dichotomous branching mutant ΔracA was followed, demonstrating that hyperbranching does not per se result in increased protein secretion.

View Article: PubMed Central - PubMed

Affiliation: Leiden University, Institute of Biology Leiden, Department Molecular Microbiology and Biotechnology, Leiden, The Netherlands.

ABSTRACT
RacA is the main Rho GTPase in Aspergillus niger regulating polarity maintenance via controlling actin dynamics. Both deletion and dominant activation of RacA (Rac(G18V)) provoke an actin localization defect and thereby loss of polarized tip extension, resulting in frequent dichotomous branching in the ΔracA strain and an apolar growing phenotype for Rac(G18V). In the current study the transcriptomics and physiological consequences of these morphological changes were investigated and compared with the data of the 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 (ΔracA, Rac(G18V), ramosa-1) 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. Finally, the fate of exocytotic (SncA) and endocytotic (AbpA, SlaB) markers in the dichotomous branching mutant ΔracA was followed, demonstrating that hyperbranching does not per se result in increased protein secretion.

Show MeSH
Related in: MedlinePlus