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Recent studies have indicated that serine phosphorylation regulates the activities of STAT1 and STAT3. However, the kinase(s) responsible and the role of serine phosphorylation in STAT function remain unresolved. In the present studies, we examined the growth factor-dependent serine phosphorylation of STAT1 and STAT3. We provide in vitro and in vivo evidence that the ERK family of mitogen-activated protein (MAP) kinases, but not JNK or p38, specifically phosphorylate STAT3 at serine 727 in respo

VDAC1 is a critical substrate of Parkin responsible for the regulation of mitophagy and apoptosis. Here, we demonstrate that VDAC1 can be either mono- or polyubiquitinated by Parkin in a PINK1-dependent manner. VDAC1 deficient with polyubiquitination (VDAC1 Poly-KR) hampers mitophagy, but VDAC1 deficient with monoubiquitination (VDAC1 K274R) promotes apoptosis by augmenting the mitochondrial calcium uptake through the mitochondrial calcium uniporter (MCU) channel. The transgenic flies expressing

Akt is a protein serine/threonine kinase that plays an important role in the mitogenic responses of cells to variable stimuli. Akt contains a pleckstrin homology (PH) domain and is activated by phosphorylation at threonine 308 and serine 473. Binding of 3'-OH phosphorylated phosphoinositides to the PH domain results in the translocation of Akt to the plasma membrane where it is activated by upstream kinases such as (phosphoinositide-dependent kinase-1 (PDK1). Over-expression of constitutively ac

The serine/threonine kinase Akt has been intensely studied for its role in growth factor-mediated cell survival for the past 5 years. On the other hand, the ongoing research effort has recently uncovered novel regulatory mechanisms and downstream effectors of Akt that demonstrate the involvement of Akt in other cellular functions such as cell cycle progression, angiogenesis, and cancer cell invasion/metastasis. Furthermore, recent studies using whole model organisms suggest additional roles for

LKB1 plays important roles in governing energy homeostasis by regulating AMP-activated protein kinase (AMPK) and other AMPK-related kinases, including the salt-inducible kinases (SIKs). However, the roles and regulation of LKB1 in lipid metabolism are poorly understood. Here we show that Drosophila LKB1 mutants display decreased lipid storage and increased gene expression of brummer, the Drosophila homolog of adipose triglyceride lipase (ATGL). These phenotypes are consistent with those of SIK3

p53 is a representative tumor suppressor whose dysfunction is a major cause of human cancer syndrome. Here we isolated flies lacking Dmp53, which encodes the single Drosophila orthologue of mammalian p53 family. Dmp53 null mutants well developed into adults, only displaying mild defects in longevity and fertility. However, genomic stability and viability of Dmp53 mutants dramatically decreased upon ionizing irradiation. Moreover, mutating Dmp53 abolished irradiation-induced apoptosis and reaper

Mutations in PINK1 (PTEN-induced putative kinase 1) are tightly linked to autosomal recessive Parkinson disease (PD). Although more than 50 mutations in PINK1 have been discovered, the role of these mutations in PD pathogenesis remains poorly understood. Here, we characterized 17 representative PINK1 pathogenic mutations in both mammalian cells and Drosophila. These mutations did not affect the typical cleavage patterns and subcellular localization of PINK1 under both normal and damaged mitochon

The ability to respond to environmental temperature variation is essential for survival in animals. Flies show robust temperature-preference behaviour (TPB) to find optimal temperatures. Recently, we have shown that Drosophila mushroom body (MB) functions as a center controlling TPB. However, neuromodulators that control the TPB in MB remain unknown. To identify the functions of dopamine in TPB, we have conducted various genetic studies in Drosophila. Inhibition of dopamine biosynthesis by genet

Protein kinase assays that use recombinant pp90rsk as a substrate were developed in an attempt to identify growth-regulated enzymes responsible for the phosphorylation and activation of pp90rsk S6 phosphotransferase activity. With this assay we have ientified a pp60v-src-, growth factor-, phorbol ester-, and vanadate-regulated serine/threonine protein kinase activity that is not related to two other cofactor-independent, growth-regulated protein kinases, pp70-S6 protein kinase and pp90rsk. The p