Limits...
Core oxidative stress response in Aspergillus nidulans.

Emri T, Szarvas V, Orosz E, Antal K, Park H, Han KH, Yu JH, Pócsi I - BMC Genomics (2015)

Bottom Line: We also found that both oxidative and salt stresses induced expression of some secondary metabolite gene clusters and the deletion of atfA enhanced the stress responsiveness of additional clusters.Our data suggest that the observed co-regulations were most likely consequences of the overlapping physiological effects of the stressors and not of the existence of a general environmental stress response.Both stress inducible and stress repressive regulations of secondary metabolism seem to be frequent features in A. nidulans.

View Article: PubMed Central - PubMed

Affiliation: Department of Biotechnology and Microbiology, Faculty of Science and Technology, University of Debrecen, P.O. Box 63, H-4032, Debrecen, Hungary. emri.tamas@science.unideb.hu.

ABSTRACT

Background: The b-Zip transcription factor AtfA plays a key role in regulating stress responses in the filamentous fungus Aspergillus nidulans. To identify the core regulons of AtfA, we examined genome-wide expression changes caused by various stresses in the presence/absence of AtfA using A. nidulans microarrays. We also intended to address the intriguing question regarding the existence of core environmental stress response in this important model eukaryote.

Results: Examination of the genome wide expression changes caused by five different oxidative stress conditions in wild type and the atfA mutant has identified a significant number of stereotypically regulated genes (Core Oxidative Stress Response genes). The deletion of atfA increased the oxidative stress sensitivity of A. nidulans and affected mRNA accumulation of several genes under both unstressed and stressed conditions. The numbers of genes under the AtfA control appear to be specific to a stress-type. We also found that both oxidative and salt stresses induced expression of some secondary metabolite gene clusters and the deletion of atfA enhanced the stress responsiveness of additional clusters. Moreover, certain clusters were down-regulated by the stresses tested.

Conclusion: Our data suggest that the observed co-regulations were most likely consequences of the overlapping physiological effects of the stressors and not of the existence of a general environmental stress response. The function of AtfA in governing various stress responses is much smaller than anticipated and/or other regulators may play a redundant or overlapping role with AtfA. Both stress inducible and stress repressive regulations of secondary metabolism seem to be frequent features in A. nidulans.

No MeSH data available.


Related in: MedlinePlus

Comparison of transcriptome data sets of stress-exposed control and ΔatfA strains. Pairwise similarities between transcriptome profiles were characterized by absolute correlations of normalized microarray data presented in Additional file 4: Table S4, and are summarized using agglomerative hierarchical cluster analysis with complete linkage
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4482186&req=5

Fig2: Comparison of transcriptome data sets of stress-exposed control and ΔatfA strains. Pairwise similarities between transcriptome profiles were characterized by absolute correlations of normalized microarray data presented in Additional file 4: Table S4, and are summarized using agglomerative hierarchical cluster analysis with complete linkage

Mentions: COSR genes were defined as genes showing unidirectional transcriptional changes under the three “severe” oxidative stress conditions tested (stress conditions generated by MSB, tBOOH and diamide). Relying on these premises, the numbers of COSR genes were 873 and 729 in the control and ΔatfA strains, respectively (Table 3). The subsequent inclusion of either h-H2O2 or NaCl or even concomitantly both stress treatment data sets into the comparative analysis of the transcriptional changes reduced markedly the number of core stress response genes (Table 3). The inclusion of all stress treatments (l-H2O2, h-H2O2 and also NaCl) almost completely emptied the group of core stress response genes; only 13 and 18 genes (Table 3) showed unidirectional transcriptional changes in all stress exposure experiments in the control strain and the ΔatfA strain, respectively. The pairwise similarities between transcriptome profiles (Fig. 2, Additional file 4: Table S4) as well as the great number of genes showing transcriptional changes only in one stress treatment (Table 3) also suggested that the different stressors had characteristic stress-specific effects on the transcriptome.Fig. 2


Core oxidative stress response in Aspergillus nidulans.

Emri T, Szarvas V, Orosz E, Antal K, Park H, Han KH, Yu JH, Pócsi I - BMC Genomics (2015)

Comparison of transcriptome data sets of stress-exposed control and ΔatfA strains. Pairwise similarities between transcriptome profiles were characterized by absolute correlations of normalized microarray data presented in Additional file 4: Table S4, and are summarized using agglomerative hierarchical cluster analysis with complete linkage
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4482186&req=5

Fig2: Comparison of transcriptome data sets of stress-exposed control and ΔatfA strains. Pairwise similarities between transcriptome profiles were characterized by absolute correlations of normalized microarray data presented in Additional file 4: Table S4, and are summarized using agglomerative hierarchical cluster analysis with complete linkage
Mentions: COSR genes were defined as genes showing unidirectional transcriptional changes under the three “severe” oxidative stress conditions tested (stress conditions generated by MSB, tBOOH and diamide). Relying on these premises, the numbers of COSR genes were 873 and 729 in the control and ΔatfA strains, respectively (Table 3). The subsequent inclusion of either h-H2O2 or NaCl or even concomitantly both stress treatment data sets into the comparative analysis of the transcriptional changes reduced markedly the number of core stress response genes (Table 3). The inclusion of all stress treatments (l-H2O2, h-H2O2 and also NaCl) almost completely emptied the group of core stress response genes; only 13 and 18 genes (Table 3) showed unidirectional transcriptional changes in all stress exposure experiments in the control strain and the ΔatfA strain, respectively. The pairwise similarities between transcriptome profiles (Fig. 2, Additional file 4: Table S4) as well as the great number of genes showing transcriptional changes only in one stress treatment (Table 3) also suggested that the different stressors had characteristic stress-specific effects on the transcriptome.Fig. 2

Bottom Line: We also found that both oxidative and salt stresses induced expression of some secondary metabolite gene clusters and the deletion of atfA enhanced the stress responsiveness of additional clusters.Our data suggest that the observed co-regulations were most likely consequences of the overlapping physiological effects of the stressors and not of the existence of a general environmental stress response.Both stress inducible and stress repressive regulations of secondary metabolism seem to be frequent features in A. nidulans.

View Article: PubMed Central - PubMed

Affiliation: Department of Biotechnology and Microbiology, Faculty of Science and Technology, University of Debrecen, P.O. Box 63, H-4032, Debrecen, Hungary. emri.tamas@science.unideb.hu.

ABSTRACT

Background: The b-Zip transcription factor AtfA plays a key role in regulating stress responses in the filamentous fungus Aspergillus nidulans. To identify the core regulons of AtfA, we examined genome-wide expression changes caused by various stresses in the presence/absence of AtfA using A. nidulans microarrays. We also intended to address the intriguing question regarding the existence of core environmental stress response in this important model eukaryote.

Results: Examination of the genome wide expression changes caused by five different oxidative stress conditions in wild type and the atfA mutant has identified a significant number of stereotypically regulated genes (Core Oxidative Stress Response genes). The deletion of atfA increased the oxidative stress sensitivity of A. nidulans and affected mRNA accumulation of several genes under both unstressed and stressed conditions. The numbers of genes under the AtfA control appear to be specific to a stress-type. We also found that both oxidative and salt stresses induced expression of some secondary metabolite gene clusters and the deletion of atfA enhanced the stress responsiveness of additional clusters. Moreover, certain clusters were down-regulated by the stresses tested.

Conclusion: Our data suggest that the observed co-regulations were most likely consequences of the overlapping physiological effects of the stressors and not of the existence of a general environmental stress response. The function of AtfA in governing various stress responses is much smaller than anticipated and/or other regulators may play a redundant or overlapping role with AtfA. Both stress inducible and stress repressive regulations of secondary metabolism seem to be frequent features in A. nidulans.

No MeSH data available.


Related in: MedlinePlus