SakA MAP kinase is involved in stress signal transduction, sexual development and spore viability in Aspergillus nidulans

Abstract

SummaryIn eukaryotic cells, environmental stress signals are transmitted by evolutionarily conserved MAPKs, such as Hog1 in the budding yeast Saccharomyces cerevisiae, Spc1 in the fission yeast Schizosaccharomyces pombe and p38/JNK in mammalian cells. Here, we report the identification of the Aspergillus nidulans sakA gene, which encodes a member of the stress MAPK family. The sakA gene is able to complement the S. pombe spc1 -defects in both osmoregulation and cell cycle progression. Moreover, SakA MAPK is activated in response to osmotic and oxidative stress in both S. pombe and A. nidulans. However, in contrast to hog1 and spc1 mutants, the sakA null mutant is not sensitive to high osmolarity stress, indicating a different regulation of the osmostress response in this fungus. On the other hand, the DsakA mutant shows development and cell-specific phenotypes. First, it displays premature steA-dependent sexual development. Second, DsakA mutant produces asexual spores that are highly sensitive to oxidative and heat shock stress and lose viability upon storage. Indeed, SakA is transiently activated early after induction of conidiation. Our results indicate that SakA MAPK is involved in stress signal transduction and repression of sexual development, and is required for spore stress resistance and survival.

The Response Regulator RRG-1 Functions Upstream of a Mitogen-activated Protein Kinase Pathway Impacting Asexual Development, Female Fertility, Osmotic Stress, and Fungicide Resistance inNeurospora crassa

“…Commercially available antibodies against mammalian or S. cerevisiae MAPKs were used to detect phospho-OS-2 (anti-p38 9211; 1:1000 dilution; Cell Signaling Technology, Beverly, MA; Kawasaki et al, 2002), and OS-2 (anti-Hog1p sc-9079; 1:600 dilution; Santa Cruz Biotechnology, Santa Cruz, CA). Incubation with secondary antibody and chemiluminescent detection were performed as described previously (Krystofova and Borkovich, 2005).…”

“…Anti-Hog1p recognizes both nonphosphorylated and phosphorylated forms of the protein, whereas anti-phospho p38 is specific for the phosphorylated MAPK. The phosphop38 antibody was previously shown to cross-react with the homologous MAPK protein, SakA, from Aspergillus nidulans (Kawasaki et al, 2002), whereas both antibodies were shown to recognize the homologous MAPK protein OSC-1 from Colletotrichum lagenarium (Kojima et al, 2004). We tested the antibodies for binding to OS-2 via Western analysis of extracts from wild-type, ⌬rrg-1, and os-2 strains (Figure 4, A-C).…”

“…A. nidulans contains a Hog1p/OS-2 family MAPK, SakA. sakA mutants are not sensitive to hyperosmotic conditions, but they undergo premature sexual development and produce asexual spores that are sensitive to oxidative and heat stress (Kawasaki et al, 2002). The lack of an osmotic phenotype is of interest, because phosphorylation of SakA is induced by exposure to both 0.8 M KCl and 10 mM hydrogen peroxide.…”

The Mitogen-Activated Protein Kinase Signal Transduction Pathways in Alternaria Species

“…The Hog1 MAPK pathway also plays a pivotal role in fungicides susceptibility. Hog1 mutants of fungi like Fusarium proliferatum (Ádám et al, 2008), Aspergillus nidulans (Kawasaki et al, 2002), C. heterostrophus (Igbaria et al, 2008) and C. lagenarium (Kojima et al, 2004) all showed tolerant to phenylpyrrole and dicarboximide fungicides. In A. alternata, the AaHog1 mutants were also resistant to dicarboximide and phenylpyrrole fungicides, but the induced level of resistance was very small, implying another signaling pathway in response to these fungicides stress (Lin and Chung, 2010).…”

Caracterização funcional do gene codificador de uma proteína com peptídeo sinal, masA, de Aspergillus fumigatus

“…(Ronen et al, 2007). Além disso, esta via está envolvida no crescimento polarizado, morfogênese (Donen et al, 2007;Teepe et al, 2007), utilização de açúcares (Reyes et al, 2006), estresse osmótico e oxidativo (Davenport et al, 1995;Han e Prade, 2002;Kawasaki et al, 2002;Furukawa et al, 2005), desenvolvimento sexual e viabilidade dos esporos (Kawasaki et al, 2002;Ichinomiya et al, 2007) e produção de penicilina (Herrmann et al, 2006). A via PKC/MAPK é requerida na transdução da resposta a presença do farnesol em células de mamíferos, S. cerevisiae, C.…”