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Axonal neuregulin signals cells of the oligodendrocyte lineage through activation of HER4 and Schwann cells through HER2 and HER3.

Vartanian T, Goodearl A, Viehöver A, Fischbach G - J. Cell Biol. (1997)

Bottom Line: We have found that oligodendrocite-type II astrocyte (O2A) progenitor cells and mature oligodendrocytes express HER2 and HER4 but no HER3.Coimmunoprecipitation experiments indicate that receptor activation in Schwann cells results in the formation of HER2:HER3 heterodimers.The use of unique neuregulin receptor combinations in oligodendrocytes and Schwann cells likely results in recruitment of different signaling pathways and thus provides a basis for different biological responses.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA.

ABSTRACT
We are interested in the signaling between axons and glia that leads to myelination and maintenance of the myelin internode, and we have focused on the role of neuregulins and their receptors. Neuregulins are a family of ligands that includes heregulin, neu differentiation factor, glial growth factor, and the acetylcholine receptor-inducing activity. Three signal transducing transmembrane receptors for neuregulins, which bear significant homology to the EGF receptor, are currently known: HER2 (erbB2), HER3 (erbB3), and HER4 (erbB4). We have found that oligodendrocite-type II astrocyte (O2A) progenitor cells and mature oligodendrocytes express HER2 and HER4 but no HER3. Schwann cells express HER2 and HER3 but little HER4. In O2A progenitor cells and oligodendrocytes, recombinant neuregulin induces the rapid tyrosine phosphorylation of only HER4. HER2 is not phosphorylated in cells of the oligodendrocyte lineage, but a physical interaction between HER2 and HER4 was detected in coimmunoprecipitation experiments. In Schwann cells, neuregulin induces the phosphorylation of both HER2 and HER3. Coimmunoprecipitation experiments indicate that receptor activation in Schwann cells results in the formation of HER2:HER3 heterodimers. Neuregulin localized immunocytochemically was present on neurites of cultured dorsal root ganglion neurons, and it was released into the medium in a form that promoted receptor tyrosine phosphorylation. Neuregulins therefore meet important criteria expected of molecules involved in axonal-glial signaling. The use of unique neuregulin receptor combinations in oligodendrocytes and Schwann cells likely results in recruitment of different signaling pathways and thus provides a basis for different biological responses.

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Neuregulin induces the tyrosine  phosphorylation of HER2 and HER3, and  the formation of HER2:HER3 heterodimers. Schwann cells were treated with a  control solution (PBS) or 100 pM neuregulin for 20 min and then lysed in ice-cold  lysis buffer. HER2, HER3, and HER4  were immunoprecipitated from lysates as  previously described. Immunoprecipitates  were resolved by 5% SDS-PAGE, proteins were transferred to PVDF membranes, and membranes were probed with  the indicated antibodies.
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Figure 6: Neuregulin induces the tyrosine phosphorylation of HER2 and HER3, and the formation of HER2:HER3 heterodimers. Schwann cells were treated with a control solution (PBS) or 100 pM neuregulin for 20 min and then lysed in ice-cold lysis buffer. HER2, HER3, and HER4 were immunoprecipitated from lysates as previously described. Immunoprecipitates were resolved by 5% SDS-PAGE, proteins were transferred to PVDF membranes, and membranes were probed with the indicated antibodies.

Mentions: Activation of neuregulin receptors in Schwann cells was studied in further detail by immunoprecipitation of neuregulin receptors followed by blotting with antiphosphotyrosine antibodies. Recent studies in which total tyrosinephosphorylated proteins were immunoprecipitated from Schwann cells treated with neuregulin demonstrated the phosphorylation of HER2 and HER3 (24). However, such an analysis precludes investigating receptor heterodimerization. In the experiments described below, Schwann cells were treated for 20 min with neuregulin or control buffer (PBS), and individual neuregulin receptors were immunoprecipitated as described in the Materials and Methods. Neuregulin induces the tyrosine phosphorylation of a 180– 190-kD band detected in both HER2 and HER3 immunoprecipitates (Fig. 6 A). We again identified a neuregulin induced mobility shift of ∼5 kD that occurs upon phosphorylation for HER2. Two antibodies were used to examine HER3 on Western blots: a monoclonal antibody that has not been mapped to a specific domain of the receptor and a polyclonal antibody that was raised against a peptide in the COOH terminus of HER3 that contains a consensus sequence for tyrosine phosphorylation. When blots were stripped and reprobed using the HER3 monoclonal antibody, a similar mobility shift was observed as broadening of the HER3 band (Fig. 6 A). This mobility shift was not observed with the HER3 polyclonal antibody because this antibody does not recognize the phosphorylated form of HER3 as well as dephospho-HER3 on Western blots (Fig. 6 A).


Axonal neuregulin signals cells of the oligodendrocyte lineage through activation of HER4 and Schwann cells through HER2 and HER3.

Vartanian T, Goodearl A, Viehöver A, Fischbach G - J. Cell Biol. (1997)

Neuregulin induces the tyrosine  phosphorylation of HER2 and HER3, and  the formation of HER2:HER3 heterodimers. Schwann cells were treated with a  control solution (PBS) or 100 pM neuregulin for 20 min and then lysed in ice-cold  lysis buffer. HER2, HER3, and HER4  were immunoprecipitated from lysates as  previously described. Immunoprecipitates  were resolved by 5% SDS-PAGE, proteins were transferred to PVDF membranes, and membranes were probed with  the indicated antibodies.
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2139859&req=5

Figure 6: Neuregulin induces the tyrosine phosphorylation of HER2 and HER3, and the formation of HER2:HER3 heterodimers. Schwann cells were treated with a control solution (PBS) or 100 pM neuregulin for 20 min and then lysed in ice-cold lysis buffer. HER2, HER3, and HER4 were immunoprecipitated from lysates as previously described. Immunoprecipitates were resolved by 5% SDS-PAGE, proteins were transferred to PVDF membranes, and membranes were probed with the indicated antibodies.
Mentions: Activation of neuregulin receptors in Schwann cells was studied in further detail by immunoprecipitation of neuregulin receptors followed by blotting with antiphosphotyrosine antibodies. Recent studies in which total tyrosinephosphorylated proteins were immunoprecipitated from Schwann cells treated with neuregulin demonstrated the phosphorylation of HER2 and HER3 (24). However, such an analysis precludes investigating receptor heterodimerization. In the experiments described below, Schwann cells were treated for 20 min with neuregulin or control buffer (PBS), and individual neuregulin receptors were immunoprecipitated as described in the Materials and Methods. Neuregulin induces the tyrosine phosphorylation of a 180– 190-kD band detected in both HER2 and HER3 immunoprecipitates (Fig. 6 A). We again identified a neuregulin induced mobility shift of ∼5 kD that occurs upon phosphorylation for HER2. Two antibodies were used to examine HER3 on Western blots: a monoclonal antibody that has not been mapped to a specific domain of the receptor and a polyclonal antibody that was raised against a peptide in the COOH terminus of HER3 that contains a consensus sequence for tyrosine phosphorylation. When blots were stripped and reprobed using the HER3 monoclonal antibody, a similar mobility shift was observed as broadening of the HER3 band (Fig. 6 A). This mobility shift was not observed with the HER3 polyclonal antibody because this antibody does not recognize the phosphorylated form of HER3 as well as dephospho-HER3 on Western blots (Fig. 6 A).

Bottom Line: We have found that oligodendrocite-type II astrocyte (O2A) progenitor cells and mature oligodendrocytes express HER2 and HER4 but no HER3.Coimmunoprecipitation experiments indicate that receptor activation in Schwann cells results in the formation of HER2:HER3 heterodimers.The use of unique neuregulin receptor combinations in oligodendrocytes and Schwann cells likely results in recruitment of different signaling pathways and thus provides a basis for different biological responses.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA.

ABSTRACT
We are interested in the signaling between axons and glia that leads to myelination and maintenance of the myelin internode, and we have focused on the role of neuregulins and their receptors. Neuregulins are a family of ligands that includes heregulin, neu differentiation factor, glial growth factor, and the acetylcholine receptor-inducing activity. Three signal transducing transmembrane receptors for neuregulins, which bear significant homology to the EGF receptor, are currently known: HER2 (erbB2), HER3 (erbB3), and HER4 (erbB4). We have found that oligodendrocite-type II astrocyte (O2A) progenitor cells and mature oligodendrocytes express HER2 and HER4 but no HER3. Schwann cells express HER2 and HER3 but little HER4. In O2A progenitor cells and oligodendrocytes, recombinant neuregulin induces the rapid tyrosine phosphorylation of only HER4. HER2 is not phosphorylated in cells of the oligodendrocyte lineage, but a physical interaction between HER2 and HER4 was detected in coimmunoprecipitation experiments. In Schwann cells, neuregulin induces the phosphorylation of both HER2 and HER3. Coimmunoprecipitation experiments indicate that receptor activation in Schwann cells results in the formation of HER2:HER3 heterodimers. Neuregulin localized immunocytochemically was present on neurites of cultured dorsal root ganglion neurons, and it was released into the medium in a form that promoted receptor tyrosine phosphorylation. Neuregulins therefore meet important criteria expected of molecules involved in axonal-glial signaling. The use of unique neuregulin receptor combinations in oligodendrocytes and Schwann cells likely results in recruitment of different signaling pathways and thus provides a basis for different biological responses.

Show MeSH
Related in: MedlinePlus