Mig6 is a negative regulator of EGF receptor-mediated skin morphogenesis and tumor formation.

The growing number of recently identified negative feedback regulators of receptor tyrosine kinases (RTKs) highlights the importance of signal attenuation and modulation for correct signaling outcome. Mitogen-inducible gene 6 (Mig6 also known as RALT or Gene 33) is a multiadaptor protein thought to be involved in the regulation of RTK and stress signaling. Here, we show that deletion of the mouse gene encoding Mig6 (designated Errfi1, which stands for ERBB receptor feedback inhibitor 1) causes hyperactivation of endogenous epidermal growth factor receptor (EGFR) and sustained signaling through the mitogen-activated protein kinase (MAPK) pathway, resulting in overproliferation and impaired differentiation of epidermal keratinocytes. Furthermore, Errfi1-/- mice develop spontaneous tumors in various organs and are highly susceptible to chemically induced formation of skin tumors. A tumor-suppressive role for Mig6 is supported by our finding that MIG6 is downregulated in various human cancers. Inhibition of endogenous Egfr signaling with the Egfr inhibitor gefitinib (Iressa) or replacement of wild-type Egfr with the kinase-deficient protein encoded by the hypomorphic Egfr(wa2) allele completely rescued skin defects in Erffi1-/- mice. Carcinogen-induced tumors displayed by Errfi1-/- mice were highly sensitive to gefitinib. These results indicate that Mig6 is a specific negative regulator of Egfr signaling in skin morphogenesis and is a novel tumor suppressor of Egfr-dependent carcinogenesis.

Mitogen-inducible gene 6 is an endogenous inhibitor of HGF/Met-induced cell migration and neurite growth.

Hepatocyte growth factor (HGF)/Met signaling controls cell migration, growth and differentiation in several embryonic organs and is implicated in human cancer. The physiologic mechanisms that attenuate Met signaling are not well understood. Here we report a mechanism by which mitogen-inducible gene 6 (Mig6; also called Gene 33 and receptor-associated late transducer) negatively regulates HGF/Met-induced cell migration. The effect is observed by Mig6 overexpression and is reversed by Mig6 small interfering RNA knock-down experiments; this indicates that endogenous Mig6 is part of a mechanism that inhibits Met signaling. Mig6 functions in cells of hepatic origin and in neurons, which suggests a role for Mig6 in different cell lineages. Mechanistically, Mig6 requires an intact Cdc42/Rac interactive binding site to exert its inhibitory action, which suggests that Mig6 acts, at least in part, distally from Met, possibly by inhibiting Rho-like GTPases. Because Mig6 also is induced by HGF stimulation, our results suggest that Mig6 is part of a negative feedback loop that attenuates Met functions in different contexts and cell types.

Expression of coiled-coil protein 1, a novel gene downstream of FGF2, in the developing brain.

Fibroblast growth factor 2 (FGF2) plays an important role in cortical development. However, the genes downstream of FGF2 that mediate its effect are largely unknown. We have performed a microarray screening of genes regulated by FGF2 using primary cortical neuron culture derived from embryonic day 14.5 (E14.5) mouse forebrains. In this study, we have analysed a previously uncharacterised gene encoding a 180-amino acid protein, hereby named 'coiled-coil protein 1 (ccp1)', that showed a modest up-regulation upon FGF2 stimulation. Northern blots and RT-PCR showed specific expression of ccp1 in multiple tissues including adult and embryonic brains. In situ hybridizations revealed that ccp1 was expressed in the cortical plate between Reelin and Tbr1-positive layers in the dorsal cortex at E15.5. Furthermore, the expression pattern of ccp1 at E13.5-E14.5 reflected some of the aspects of tangential migration of cortical progenitors during the early phase. We observed that the expressed ccp1 protein was localised to endo/lysosomal compartment in the cell body as well as to vesicles present in the processes of primary cortical neurons and oligodendrocyte cell line.

Manufacturing, characterization and control of cell-based medicinal products: challenging paradigms toward commercial use.

During the past decade, a large number of cell-based medicinal products have been tested in clinical trials for the treatment of various diseases and tissue defects. However, licensed products and those approaching marketing authorization are still few. One major area of challenge is the manufacturing and quality development of these complex products, for which significant manipulation of cells might be required. While the paradigms of quality, safety and efficacy must apply also to these innovative products, their demonstration may be demanding. Demonstration of comparability between production processes and batches may be difficult for cell-based medicinal products. Thus, the development should be built around a well-controlled manufacturing process and a qualified product to guarantee reproducible data from nonclinical and clinical studies.