hTID-1 defines a novel regulator of c-Met Receptor signaling in renal cell carcinomas

The c-Met receptor tyrosine kinase (MetR) is frequently overexpressed and constitutively phosphorylated in a number of human malignancies. Activation of the receptor by its ligand, hepatocyte growth factor (HGF), leads to increased cell proliferation, motility, survival and disruption of adherens junctions. In this study, we show that hTid-1, a DNAJ/Hsp40 chaperone, represents a novel modulator of the MetR signaling pathway. hTid-1 is a co-chaperone of the Hsp70 family of proteins, and has been shown to regulate a number of cellular signaling proteins including several involved in tumorigenic and apoptotic pathways. In this study we demonstrate that hTid-1 binds to unphosphorylated MetR and becomes dissociated from the receptor upon HGF stimulation. Overexpression of the short form of hTid-1 (hTid-1S) in 786-0 renal clear cell carcinomas (RCCs) enhances MetR kinase activity leading to an increase in HGF-mediated cell migration with no discernible effect on cell proliferation. By contrast, knockdown of hTid-1 markedly impairs both the onset and amplitude of MetR phosphorylation in response to HGF without altering receptor protein levels. hTid-1-depleted cells display defective migratory properties, coincident with inhibition of ERK/MAP kinase and STAT3 pathways. Taken together, our findings denote hTid-1S as an essential regulatory component of MetR signaling. We propose that the binding of hTid-1S to MetR may stabilize the receptor in a ligand-competent state and this stabilizing function may influence conformational changes that take place during the catalytic cycle that promote kinase activation. Given the prevalence of HGF/MetR pathway activation in human cancers, targeted inhibition of hTid-1 may be a useful therapeutic in the management of MetR-dependent malignancies

Folate depletion during pregnancy and lactation reduces genomic DNA methylation in murine adult offspring

The developmental origins of adult health and disease (DOHaD) hypothesis that argues for a causal relationship between under-nutrition during early life and increased risk for a range of diseases in adulthood is gaining epidemiological support. One potential mechanism mediating these effects is the modulation of epigenetic markings, specifically DNA methylation. Since folate is an important methyl donor, alterations in supply of this micronutrient may influence the availability of methyl groups for DNA methylation. We hypothesised that low folate supply in utero and post-weaning would alter the DNA methylation profile of offspring. In two separate 2 × 2 factorial designed experiments, female C57Bl6/J mice were fed low- or control/high-folate diets during mating, and through pregnancy and lactation. Offspring were weaned on to either low- or control/high-folate diets, resulting in 4 treatment groups/experiment. Genomic DNA methylation was measured in the small intestine (SI) of 100-day-old offspring. In both experiments, SI genomic DNA from offspring of low-folate-fed dams was significantly hypomethylated compared with the corresponding control/high folate group (P = 0.009/P = 0.006, respectively). Post-weaning folate supply did not affect SI genomic DNA methylation significantly. These observations demonstrate that early life folate depletion affects epigenetic markings, that this effect is not modulated by post-weaning folate supply and that altered epigenetic marks persist into adulthood