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HSP70 binds to SHP2 and has effects on the SHP2-related EGFR/GAB1 signaling pathway.

ABSTRACT: The Src homology phosphotyrosyl phosphatase, SHP2, is a positive effector of EGFR signaling. However, the molecular mechanism and biological functions of SHP2 regulation are still not completely known. To better understand the cellular processes in which SHP2 participates, we carried out mass spectrometry to find SHP2 binding proteins. FLAG-SHP2 complexes were isolated by affinity purification, and associated proteins were identified by in-gel trypsin digestion followed by LC/MS/MS mass spectrometry. Among the identified proteins, we focus in this report on the heat shock protein 70 (HSP70). Physical interactions of SHP2 with HSP70 were confirmed in vivo. Further experiments demonstrate that EGF does not activate binding of SHP2 with HSP70 rather the binding appears to be constitutive. However, the formation of an HSP70/SHP2 complex affected the binding of SHP2 with EGFR and (or) GAB1. These data suggest that binding of HSP70 with SHP2 regulates to some extent the EGF signaling pathway. In addition, immunostaining experiments indicated that SHP2 and HSP70 co-localized in the cell membrane region after EGF treatment. Our findings propose a possible involvement of HSP70 in the regulation of EGF signaling pathway by SHP2.

SUBMITTER: Yoo JC

PROVIDER: S-EPMC1698467 | biostudies-literature | 2006 Dec

REPOSITORIES: biostudies-literature

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HSP70 binds to SHP2 and has effects on the SHP2-related EGFR/GAB1 signaling pathway.

Yoo Jae Cheal JC Hayman Michael J MJ

Biochemical and biophysical research communications 20061103 4

The Src homology phosphotyrosyl phosphatase, SHP2, is a positive effector of EGFR signaling. However, the molecular mechanism and biological functions of SHP2 regulation are still not completely known. To better understand the cellular processes in which SHP2 participates, we carried out mass spectrometry to find SHP2 binding proteins. FLAG-SHP2 complexes were isolated by affinity purification, and associated proteins were identified by in-gel trypsin digestion followed by LC/MS/MS mass spectrom ...[more]

PMID: 17097051

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Project description:Grb2-associated binder 1 (Gab1) coordinates various receptor tyrosine kinase signaling pathways. Although skeletal muscle differentiation is regulated by some growth factors, it remains elusive whether Gab1 coordinates myogenic signals. Here, we examined the molecular mechanism of insulin-like growth factor-I (IGF-I)-mediated myogenic differentiation, focusing on Gab1 and its downstream signaling. Gab1 underwent tyrosine phosphorylation and subsequent complex formation with protein-tyrosine phosphatase SHP2 upon IGF-I stimulation in C2C12 myoblasts. On the other hand, Gab1 constitutively associated with phosphatidylinositol 3-kinase regulatory subunit p85. To delineate the role of Gab1 in IGF-I-dependent signaling, we examined the effect of adenovirus-mediated forced expression of wild-type Gab1 (Gab1(WT)), mutated Gab1 that is unable to bind SHP2 (Gab1(DeltaSHP2)), or mutated Gab1 that is unable to bind p85 (Gab1(Deltap85)), on the differentiation of C2C12 myoblasts. IGF-I-induced myogenic differentiation was enhanced in myoblasts overexpressing Gab1(DeltaSHP2), but inhibited in those overexpressing either Gab1(WT) or Gab1(Deltap85). Conversely, IGF-I-induced extracellular signal-regulated kinase 1/2 (ERK1/2) activation was significantly repressed in myoblasts overexpressing Gab1(DeltaSHP2) but enhanced in those overexpressing either Gab1(WT) or Gab1(Deltap85). Furthermore, small interference RNA-mediated Gab1 knockdown enhanced myogenic differentiation. Overexpression of catalytic-inactive SHP2 modulated IGF-I-induced myogenic differentiation and ERK1/2 activation similarly to that of Gab1(DeltaSHP2), suggesting that Gab1-SHP2 complex inhibits IGF-I-dependent myogenesis through ERK1/2. Consistently, the blockade of ERK1/2 pathway reversed the inhibitory effect of Gab1(WT) overexpression on myogenic differentiation, and constitutive activation of the ERK1/2 pathway suppressed the enhanced myogenic differentiation by overexpression of Gab1(DeltaSHP2). Collectively, these data suggest that the Gab1-SHP2-ERK1/2 signaling pathway comprises an inhibitory axis for IGF-I-dependent myogenic differentiation.

Project description:Influenza A virus (IAV) is a highly contagious pathogen, causing acute respiratory illnesses in human beings and animals and frequently giving rise to epidemic outbreaks. Evasion by IAV of host immunity facilitates viral replication and spread, which can be initiated through various mechanisms, including epidermal growth factor receptor (EGFR) activation. However, how EGFR mediates the suppression of antiviral systems remains unclear. Here, we examined host innate immune responses and their relevant signaling to EGFR upon IAV infection. IAV was found to induce the phosphorylation of EGFR and extracellular signal-regulated kinase (ERK) at an early stage of infection. Inhibition of EGFR or ERK suppressed the viral replication but increased the expression of type I and type III interferons (IFNs) and interferon-stimulated genes (ISGs), supporting the idea that IAV escapes from antiviral innate immunity by activating EGFR/ERK signaling. Meanwhile, IAV infection also induced the activation of Src homology region 2-containing protein tyrosine phosphatase 2 (SHP2). Pharmacological inhibition or small interfering RNA (siRNA)-based silencing of SHP2 enhanced the IFN-dependent antiviral activity and reduced virion production. Furthermore, knockdown of SHP2 attenuated the EGFR-mediated ERK phosphorylation triggered by viral infection or EGF stimulation. Conversely, ectopic expression of constitutively active SHP2 noticeably promoted ERK activation and viral replication, concomitant with diminished immune function. Altogether, the results indicate that SHP2 is crucial for IAV-induced activation of the EGFR/ERK pathway to suppress host antiviral responses.IMPORTANCE Viral immune evasion is the most important strategy whereby viruses evolve for their survival. This work shows that influenza A virus (IAV) suppressed the antiviral innate immunity through downregulation of IFNs and ISGs by activating EGFR/ERK signaling. Meanwhile, IAV also induced the activation of protein tyrosine phosphatase SHP2, which was found to be responsible for modulating the EGFR-mediated ERK activity and subsequent antiviral effectiveness both in vitro and in vivo The results suggest that SHP2 is a key signal transducer between EGFR and ERK and plays a crucial role in suppressing host innate immunity during IAV infection. The finding enhances our understanding of influenza immune evasion and provides a new therapeutic approach to viral infection.

Dataset Information

HSP70 binds to SHP2 and has effects on the SHP2-related EGFR/GAB1 signaling pathway.

Publications

HSP70 binds to SHP2 and has effects on the SHP2-related EGFR/GAB1 signaling pathway.

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