The p38 signal transduction pathway participates in the oxidative stress-mediated translocation of DAF-16 to Caenorhabditis elegans nuclei

2005 ◽  
Vol 126 (6-7) ◽  
pp. 642-647 ◽  
Author(s):  
Masaki Kondo ◽  
Sumino Yanase ◽  
Takamasa Ishii ◽  
Philip S. Hartman ◽  
Kunihiro Matsumoto ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Signal Transduction ◽  
Caenorhabditis Elegans ◽  
Signal Transduction Pathway ◽  
Transduction Pathway

Genetic regulation of entry into meiosis in Caenorhabditis elegans

Development ◽  
1998 ◽  
Vol 125 (10) ◽  
pp. 1803-1813 ◽  
Author(s):  
L.C. Kadyk ◽  
J. Kimble
Keyword(s):  
Signal Transduction ◽  
Caenorhabditis Elegans ◽  
Germ Cells ◽  
Genetic Regulation ◽  
Signal Transduction Pathway ◽  
Mitotic Cell ◽  
Transduction Pathway ◽  
Germline Development ◽  
Large Tumor ◽  
Regulatory Pathways

The Caenorhabditis elegans germline is composed of mitotically dividing cells at the distal end that give rise to meiotic cells more proximally. Specification of the distal region as mitotic relies on induction by the somatic distal tip cell and the glp-1 signal transduction pathway. However, the genetic control over the transition from mitosis to meiosis is not understood. In this paper, we report the identification of a gene, gld-2, that has at least two functions in germline development. First, gld-2 is required for normal progression through meiotic prophase. Second, gld-2 promotes entry into meiosis from the mitotic cell cycle. With respect to this second function, gld-2 appears to be functionally redundant with a previously described gene, gld-1 (Francis, R., Barton, M. K., Kimble, J. and Schedl, T. (1995) Genetics 139, 579–606). Germ cells in gld-1(o) and gld-2 single mutants enter meiosis at the normal time, but germ cells in gld-2 gld-1(o) double mutants do not enter meiosis. Instead, the double mutant germline is mitotic throughout and forms a large tumor. We suggest that gld-1 and gld-2 define two independent regulatory pathways, each of which can be sufficient for entry into meiosis. Epistasis analyses show that gld-1 and gld-2 work downstream of the glp-1 signal transduction pathway. Therefore, we hypothesize that glp-1 promotes proliferation by inhibiting the meiosis-promoting functions of gld-1 and gld-2.

scholarly journals A Ras-mediated signal transduction pathway is involved in the control of sex myoblast migration in Caenorhabditis elegans

Development ◽  
1996 ◽  
Vol 122 (9) ◽  
pp. 2823-2833 ◽  
Author(s):  
M. Sundaram ◽  
J. Yochem ◽  
M. Han
Keyword(s):  
Signal Transduction ◽  
Caenorhabditis Elegans ◽  
Growth Factor Receptor ◽  
Signal Transduction Pathway ◽  
Body Region ◽  
Transduction Pathway ◽  
Loss Of Function ◽  
Ras Pathway ◽  
Mosaic Analysis ◽  
Sex Myoblasts

Sex myoblast migration in the Caenorhabditis elegans hermaphrodite represents a simple, genetically amenable model system for studying how cell migration is regulated during development. Two separable components of sex myoblast guidance have been described: a gonad-independent mechanism sufficient for the initial anterior migration to the mid-body region, and a gonad-dependent mechanism required for precise final positioning (J. H. Thomas, M. J. Stern and H. R. Horvitz (1990) Cell 62, 1041–1052). Here, we demonstrate a role for a Ras-mediated signal transduction pathway in controlling sex myoblast migration. Loss-of-function mutations in let-60 ras, ksr-1, lin-45 raf, let-537/mek-2 or sur-1/mpk-1 cause defects in sex myoblast final positions that resemble those seen in gonad-ablated animals, while constitutively active let-60 ras(G13E) trans-genes allow fairly precise positioning to occur in the absence of the gonad. A mosaic analysis demonstrated that let-60 ras is required within the sex myoblasts to control proper positioning. Our results suggest that gonadal signals normally stimulate let-60 ras activity in the sex myoblasts, thereby making them competent to sense or respond to positional cues that determine the precise endpoint of migration. let-60 ras may have additional roles in sex myoblast guidance as well. Finally, we have also investigated genetic interactions between let-60 ras and other genes important for sex myoblast migration, including egl-15, which encodes a fibroblast growth factor receptor tyrosine kinase (D. L. DeVore, H. R. Horvitz and M. J. Stern (1995) Cell 83, 611–623). Since mutations reducing Ras pathway activity cause a different phenotype than those reducing egl-15 activity and since constitutive Ras activity only partially suppresses the migration defects of egl-15 mutants, we argue that let-60 ras and egl-15 do not act together in a single linear pathway.

scholarly journals Dissociation of Akt1 from its negative regulator JIP1 is mediated through the ASK1–MEK–JNK signal transduction pathway during metabolic oxidative stress

2005 ◽  
Vol 170 (1) ◽  
pp. 61-72 ◽  
Author(s):  
Jae J. Song ◽  
Yong J. Lee
Keyword(s):  
Oxidative Stress ◽  
Signal Transduction ◽  
Feedback Loop ◽  
Signal Transduction Pathway ◽  
Glucose Deprivation ◽  
Negative Regulator ◽  
Transduction Pathway ◽  
Metabolic Oxidative Stress ◽  
Regulatory Feedback Loop ◽  
Jnk Activation

We have previously observed that metabolic oxidative stress–induced death domain–associated protein (Daxx) trafficking is mediated by the ASK1–SEK1–JNK1–HIPK1 signal transduction pathway. The relocalized Daxx from the nucleus to the cytoplasm during glucose deprivation participates in a positive regulatory feedback loop by binding to apoptosis signal–regulating kinase (ASK) 1. In this study, we report that Akt1 is involved in a negative regulatory feedback loop during glucose deprivation. Akt1 interacts with c-Jun NH2-terminal kinase (JNK)–interacting protein (JIP) 1, and Akt1 catalytic activity is inhibited. The JNK2-mediated phosphorylation of JIP1 results in the dissociation of Akt1 from JIP1 and subsequently restores Akt1 enzyme activity. Concomitantly, Akt1 interacts with stress-activated protein kinase/extracellular signal–regulated kinase (SEK) 1 (also known as MKK4) and inhibits SEK1 activity. Knockdown of SEK1 leads to the inhibition of JNK activation, JIP1–JNK2 binding, and the dissociation of Akt1 from JIP1 during glucose deprivation. Knockdown of JIP1 also leads to the inhibition of JNK activation, whereas the knockdown of Akt1 promotes JNK activation during glucose deprivation. Altogether, our data demonstrate that Akt1 participates in a negative regulatory feedback loop by interacting with the JIP1 scaffold protein.

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