CoChat
Sign Up
Cited by 124Cytokine Signaling Pathways and InteractionsProtein Tyrosine Phosphatasesinterferon and immune responses

The Comparative Roles of Suppressor of Cytokine Signaling-1 and -3 in the Inhibition and Desensitization of Cytokine Signaling

Open access
Wormald, Samuel, Zhang, Jian-Guo, Krebs, Danielle L., Mielke, Lisa A., Silver, Jeremy, Alexander, Warren S., Speed, Terence P., Nicola, Nicos A. +1 more·2006·Journal of Biological Chemistry
DOI 10.1074/jbc.m509595200
Open this paper in CoChat — free accountOpen PDF

Abstract

Negative feedback is a mechanism commonly employed in biological processes as a means of maintaining homeostasis. We have investigated the roles of suppressor of cytokine signaling (SOCS) proteins in regulating the kinetics of negative feedback in response to cytokine signaling. In mouse livers and bone marrow-derived macrophages, both interferon-gamma (IFNgamma) and interleukin-6 (IL-6) rapidly induced the tyrosine phosphorylation of signal transducer and activator of transcription-1 (STAT1) and STAT3. STAT3 tyrosine phosphorylation was bi-phasic in response to continuous IL-6 signaling. In macrophages lacking Socs3, however, continuous IL-6 signaling induced uniformly high levels of STAT3 tyrosine phosphorylation, and early IL-6-inducible genes were inappropriately expressed at intermediate time points. SOCS3 therefore imposes bi-phasic kinetics upon IL-6 signaling. Compared with Socs3 mRNA, Socs1 mRNA was induced relatively slowly, and SOCS1 simply attenuated the duration of IFNgamma signaling. Surprisingly, heightened Socs1 mRNA expression but minimal STAT1 tyrosine phosphorylation was observed after prolonged stimulation with IFNgamma, indicating that STAT1 may not play a large role in inducing Socs1 mRNA during steady-state IFNgamma signaling. We also demonstrate that both SOCS1 and SOCS3 can desensitize primary bone marrow-derived macrophages to IFNgamma and IL-6 signaling, respectively. Consistent with the kinetics with which Socs1 and Socs3 mRNAs were induced, SOCS3 desensitized cells to IL-6 rapidly, whereas SOCS1-mediated desensitization to IFNgamma occurred at later time points. The kinetics with which SOCS proteins are induced by cytokine may therefore be a parameter that is "hard-wired" into specific cytokine signaling pathways as a means of tailoring the kinetics with which cells become desensitized.

AI snapshot

Written from the paper’s full text.

TL;DR

This study compares SOCS1 and SOCS3 in IFNγ and IL-6 signaling, showing SOCS3 imposes bi-phasic STAT3 kinetics and rapid desensitization to IL-6, whereas SOCS1 slowly attenuates IFNγ signaling and desensitizes cells later. Both SOCS proteins can desensitize primary macrophages, with induction kinetics tailored to the cytokine.

Key findings

  • In mouse livers, IFNγ and IL-6 rapidly induced STAT1/STAT3 tyrosine phosphorylation; STAT3 phosphorylation declined to near basal by 4 h, while STAT1 phosphorylation declined by 4 h after IFNγ but by only 1 h after IL-6. SOCS1 protein peaked at 2–4 h after IFNγ and was maintained for at least 8 h; SOCS3 protein peaked at 30 min–1 h after IL-6, and IFNγ induced barely detectable SOCS3.
  • In bone marrow-derived macrophages, continuous IL-6 produced bi-phasic STAT3 phosphorylation: first between 15–30 min and second from 120 min onward. Socs3 mRNA peaked at 30 min, was minimal at 60–90 min, and re-established by 180 min. In Socs3−/Δ macrophages, STAT3 phosphorylation remained high, and IL-6-inducible Gadd45γ and Ttp were sustained or heightened.
  • SOCS1 effects on STAT1 phosphorylation were not apparent until ~90 min after IFNγ, ~60 min later than SOCS3 effects in IL-6. Socs1 mRNA was induced slowly but remained near-maximal from 60 min to at least 480 min despite low STAT1 phosphorylation after 240 min. Both Socs1 and Socs3 mRNAs had a half-life of ~30 min.
  • Both SOCS3 and SOCS1 desensitized macrophages to repeated IL-6 or IFNγ, respectively. SOCS3-mediated desensitization to IL-6 occurred rapidly (after 60, 90, 120, and 240 min), whereas SOCS1-mediated desensitization to IFNγ occurred at 120 min and later; limited desensitization to IL-6 remained in Socs3-deficient cells.

Methods

  • C57BL/6 mice were injected with saline, IL-6 (500 µg/kg), or IFNγ (250 µg/kg); livers were collected over a 16-h time course for immunoprecipitation/Western blotting and real-time PCR.
  • Primary bone marrow-derived macrophages from C57BL/6, Socs3−/Δ, Ifnγ−/−, and Socs1−/−Ifnγ−/− mice were stimulated with IL-6 (250 ng/ml) or IFNγ (125 ng/ml), including pulsed stimulations and actinomycin-D treatment for mRNA stability assays.
  • Microarray time-course analysis used MGU74Av2 GeneChips with livers from Ifnγ−/− and Ifnγ−/−Socs1−/− mice; genes changed >1.7-fold over two consecutive samples were clustered with GeneCluster2, and Q-PCR was normalized to Pbgd.

Limitations

  • The paper states that in vivo liver responses came from a single cytokine injection, whereas macrophage experiments used continuous stimulation, which may explain differences between systems. It also notes that microarray analysis used only a single liver per time point, and some gene clusters were variable and not specifically IFNγ-regulated.
  • The paper states that the specific role of SOCS1 in desensitizing cells to IFNγ at later times is difficult to clarify because other factors, such as SHP-2 or T-cell protein-tyrosine phosphatase, also contribute. It also notes that Socs3-deficient hepatocytes and mouse embryonic fibroblasts showed basal STAT3 activation, limiting their use.
  • Evident from the text: SOCS protein half-lives are inferred from mRNA and protein kinetics rather than directly measured, and desensitization in Socs3-deficient cells still showed limited IL-6 desensitization, indicating additional SOCS3-independent mechanisms.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1074/jbc.m509595200

Cites

44 of 44 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

22 of 57 cited sources checked · 14 supported · 0 flagged · accuracy not yet measured

  • Premisecitation

    SOCS1 and SOCS3 proteins can both inhibit JAK phosphorylation of STAT, creating a negative feedback loop that attenuates cytokine signal transduction.

    “SOCS1 and SOCS3 proteins can both inhibit JAK phosphorylation of STAT, thus creating a negative feedback loop that attenuates cytokine signal transduction, although the mechanisms by which they act appear to differ.”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites [19] Endo, 1997, Nature source
    • cites [20] Nicholson, 1999, EMBO J. source

      The section on STAT3 tyrosine phosphorylation reports that both SOCS-1 and SOCS-3 inhibit LIF-induced STAT3 phosphorylation in M1 cells. The Introduction describes a negative feedback loop for SOCS-1 only, not SOCS-3; the discussion (p. 382) also says SOCS-3 did not directly inhibit JAK kinase activity in the assay. Thus the shared reduction in STAT3 phosphorylation is supported, but a negative feedback loop for both proteins—and direct JAK inhibition by both—is not established. (LLM, conf=0.84)

      Experimental — accuracy not yet measured
  • Premisecitation

    SOCS1 functions by binding directly to JAK proteins.

    “Whereas SOCS1 functions by binding directly to JAK proteins, SOCS3 inhibits signaling by binding to phosphorylated tyrosine sites on the cytoplasmic domain of the receptor (19,20).”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites [19] Endo, 1997, Nature source
    • cites [20] Nicholson, 1999, EMBO J. source
  • Premisecitation

    Mice lacking Socs3 die during embryogenesis.

    “Mice lacking Socs3 die during embryogenesis (23);”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [23] Roberts, 2001, Proc. Natl. Acad. Sci. U. S. A. source
  • Premisecitation

    SOCS3 inhibits signaling by binding to phosphorylated tyrosine sites on the cytoplasmic domain of the receptor.

    “Whereas SOCS1 functions by binding directly to JAK proteins, SOCS3 inhibits signaling by binding to phosphorylated tyrosine sites on the cytoplasmic domain of the receptor (19,20).”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites [19] Endo, 1997, Nature source
    • cites [20] Nicholson, 1999, EMBO J. source

      The discussion (p. 382) says SOCS-3 inhibits IL-6 and LIF signaling, but presents binding to receptor phosphotyrosine residues as one possible mechanism, not an established one. The citing sentence states that mechanism as fact. (LLM, conf=0.90)

      Experimental — accuracy not yet measured
  • Premisecitation

    STAT3 activates transcription of Socs3 mRNA by associating with the 5' promoter region of the Socs3 gene.

    “STAT3 activates the transcription of Socs3 mRNA by associating with the 5Ј promoter region of the Socs3 gene (17).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [17] Auernhammer, 1999, Proc. Natl. Acad. Sci. U. S. A. source
  • May combine two claims. 39
  • Classified as probably not a substantial claim. 8

  • May combine two claims.

    Premisecitation

    IL-6 signaling in the absence of SOCS3 resulted in prolonged phosphorylation of STAT1 and a qualitative shift in the transcriptional response of IL-6 toward that typical of IFNγ.

    “Surprisingly, IL-6 signaling in the absence of SOCS3 resulted in the prolonged phosphorylation of STAT1 and a qualitative shift in the transcriptional response of IL-6 toward that typical of IFN␥ (16,24,25).”
    Quote in the paperSubstantial claim1 of 3 sources checked
    • cites [16] Wormald, 2003, J. Biol. Chem. source
    • cites [24] Croker, 2003, Nat. Immunol. source
    • cites [25] Lang, 2003, Nat. Immunol. source

  • May combine two claims.

    Premisecitation

    Both IFNγ and IL-6 can activate JAK1 and JAK2, and subsequently STAT1 and STAT3.

    “Both IFN␥ and IL-6 can activate JAK1 (4 -6) and JAK2 (7-10), and subsequently STAT1 (11,12) and STAT3 (6,13,14).”
    Quote in the paperSubstantial claim2 of 9 sources checked
    • cites [4] Kaplan, 1996, J. Biol. Chem. source
    • cites [5] Greenlund, 1994, EMBO J. source

      The Discussion reports that IFNγ rapidly activates JAK1 and JAK2, and the section on Y440 phosphorylation reports IFNγ-induced activation of p91. The paper mentions IL-6 receptor phosphorylation but does not establish that IL-6 activates JAK1, JAK2, STAT1, or STAT3; it also does not report STAT3 activation by IFNγ. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
    • cites [6] Lutticken, 1994, Science source
    • cites [7] Kotenko, 1995, J. Biol. Chem. source
    • cites [8] Bach, 1996, Mol. Cell Biol. source

      The paper’s main-text excerpt (passage [5]; section and page not supplied) links IFNγ receptor signaling to JAK2 recruitment, supporting the IFNγ–JAK2 part of the cited statement. It does not establish IL-6 activation of JAK2. The citations attached to JAK1, STAT1, and STAT3 in the citing sentence are separate from this source’s citation to JAK2. (LLM, conf=0.85)

      Experimental — accuracy not yet measured
    • cites [9] Stahl, 1994, Science source
    • cites [10] Narazaki, 1994, Proc. Natl. Acad. Sci. U. S. A. source
    • cites [11] Shuai, 1993, Science source
    • cites [12] Harroch, 1994, J. Biol. Chem. source

  • May combine two claims.

    Interpretationreasoning

    Signaling by IFNγ and IL-6 is fundamentally similar, and activity of SOCS3 is required to sculpt the cellular response to IL-6 and thereby discriminate it from that of IFNγ.

    “This indicates that signaling by IFN␥ and IL-6 is fundamentally similar, and that the activity of SOCS3 is required to sculpt the cellular response to IL-6 and thereby discriminate it from that of IFN␥.”
    Quote in the paperSubstantial claim1 of 3 sources checked
    • cites [16] Wormald, 2003, J. Biol. Chem. source

      The SOCS section (page not supplied) reports that IL-6 induced IFNγ-associated genes in cells lacking SOCS3 and says SOCS3 plays an important role in sculpting the IL-6 response. It does not establish that IFNγ and IL-6 signaling are fundamentally similar or that SOCS3 is required to distinguish their responses; it says the exact nature of SOCS3’s role remains undetermined. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
    • cites [24] Croker, 2003, Nat. Immunol. source
    • cites [25] Lang, 2003, Nat. Immunol. source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    T-cell protein-tyrosine phosphatase has been shown to potently desensitize cells to repeated IFNγ stimulation.

    “In the case of IFN␥ signaling, the T-cell protein-tyrosine phosphatase has been shown to potently desensitize cells to repeated stimulation (28).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [28] Sakamoto, 2004, J. Biol. Chem. source

      The Results passages describing Figs. 5–6 show reduced IFNγ-induced Stat1 activation after IFNβ pretreatment and implicate Tc-PTP in enhanced Stat1 dephosphorylation. They do not show desensitization caused by repeated IFNγ stimulation; the prior exposure was to IFNβ. Page numbers are not available in our copy. (LLM, conf=0.88)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Premisecitation

    Phosphorylated STATs dimerize and are transported to the nucleus, where they bind promoter sequences and activate transcription of genes including SOCS1 and SOCS3.

    “The phosphorylated STATs (P-STATs) then dimerize and are transported to the nucleus, where they bind to promoter sequences, and activate the transcription of a suite of genes, among which are those encoding the suppressor of cytokine signaling-1 (SOCS1) and SOCS3 proteins (15,16).”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites [15] Starr, 1997, Nature source
    • cites [16] Wormald, 2003, J. Biol. Chem. source

      The Fig. 1 caption (Conclusions; page unavailable) says phosphorylated STATs dimerize, enter the nucleus, and induce transcription of cytokine-regulated genes. The SOCS section suggests STAT3-mediated induction of SOCS3, and the PIAS section describes STAT association with DNA. Our copy does not specifically say that STATs bind promoter sequences or activate transcription of SOCS1. (LLM, conf=0.84)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Premisecitation

    Despite the physiologically distinct functions of IFNγ and IL-6, the signaling mechanisms by which they elicit cellular responses are similar, and in the case of IL-6 are distinguished at least in part through the activity of SOCS3.

    “Despite the physiologically distinct functions of IFN␥ and IL-6, the signaling mechanisms by which they elicit their cellular responses are similar, and in the case of IL-6 are distinguished at least in part through the activity of SOCS3 (16,24,25).”
    Quote in the paperSubstantial claim1 of 3 sources checked
    • cites [16] Wormald, 2003, J. Biol. Chem. source
    • cites [24] Croker, 2003, Nat. Immunol. source
    • cites [25] Lang, 2003, Nat. Immunol. source

  • May combine two claims.

    Interpretationcitation

    IFNγ signaling was simply attenuated in duration by SOCS1, a finding consistent with previous observations.

    “In contrast to the bi-phasic manner in which IL-6 signaling was regulated by SOCS3, IFN␥ signaling was simply attenuated in duration by SOCS1, a finding consistent with previous observations (30).”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [30] Brysha, 2001, J. Biol. Chem. source
    • Rests on an assumption: Tyrosine phosphorylation of STAT proteins is a valid measure of cytokine signaling and desensitization.

  • May combine two claims.

    Premisecitation

    Each of these stimuli activates the glycoprotein-130/STAT3 or G-CSF-receptor/STAT3 signaling pathways, which are known to be inhibited by SOCS3 in vivo.

    “Interestingly, each of these stimuli activates the glycoprotein-130/STAT3 or the granulocytecolony stimulating factor-receptor/STAT3 signaling pathways, which are known to be inhibited by SOCS3 in vivo (24 -26, 29, 40, 41).”
    Quote in the paperSubstantial claim1 of 6 sources checked
    • cites [24] Croker, 2003, Nat. Immunol. source
    • cites [25] Lang, 2003, Nat. Immunol. source
    • cites [26] Yasukawa, 2003, Nat. Immunol. source
    • cites [29] Croker, 2004, Immunity source
    • cites [40] Takahashi, 2003, EMBO J. source
    • cites [41] Kimura, 2004, J. Biol. Chem. source

  • May combine two claims.

    Interpretationcitation

    Interferon regulatory factor-1 is a likely candidate for sustaining Socs1 mRNA expression because it is induced by STAT1 and can associate with the Socs1 promoter to activate transcription of Socs1 mRNA.

    “One likely candidate is interferon regulatory factor-1, because it is induced by STAT1 (32,42,43) and can associate with the Socs1 promoter to activate the transcription of Socs1 mRNA (18).”
    Quote in the paperSubstantial claim2 of 4 sources checked
    • cites [32] Sims, 1993, Mol. Cell Biol. source
    • cites [42] Haque, 1994, J. Biol. Chem. source
    • cites [43] Pine, 1994, EMBO J. source
    • cites [18] Saito, 2000, J. Immunol. source

  • May combine two claims.

    Findingreasoning

    SOCS3 desensitized cells to IL-6 rapidly, whereas SOCS1-mediated desensitization to IFNγ occurred at later time points.

    “SOCS3 desensitized cells to IL-6 rapidly, whereas SOCS1mediated desensitization to IFN␥ occurred at later time points.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    STAT1 phosphorylation declined to basal levels after 4 h in response to IFNγ but after only 1 h in response to IL-6.

    “phosphorylation declined to basal levels after 4 h in response to IFN␥ but after only 1 h in response to IL-6 (Fig. 1B).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Heightened Socs1 mRNA expression but minimal STAT1 tyrosine phosphorylation was observed after prolonged stimulation with IFNγ.

    “Surprisingly, heightened Socs1 mRNA expression but minimal STAT1 tyrosine phosphorylation was observed after prolonged stimulation with IFN␥”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Both SOCS1 and SOCS3 can desensitize primary bone marrow-derived macrophages to IFNγ and IL-6 signaling, respectively.

    “We also demonstrate that both SOCS1 and SOCS3 can desensitize primary bone marrowderived macrophages to IFN␥ and IL-6 signaling, respectively.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Both IFNγ and IL-6 rapidly induced activation of STATs, and in the absence of Socs1 and Socs3, respectively, continuous cytokine stimulation resulted in sustained activation of STATs.

    “Both IFN␥ and IL-6 rapidly induced the activation of STATs, and in the absence of Socs1 and Socs3, respectively, continuous cytokine stimulation resulted in the sustained activation of STATs.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The kinetics of induction of SOCS1 by IL-6 were similar to those induced by IFNγ, but the magnitude was greatly reduced.

    “In contrast, whereas the kinetics of induction of SOCS1 by IL-6 were similar to those induced by IFN␥, the magnitude was greatly reduced.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In the absence of Socs3, tyrosine phosphorylation of STAT3 in response to a 15-min pulse of IL-6 is extended until at least 90 min, with low-level phosphorylation also apparent at later time points.

    “In the absence of Socs3, tyrosine phosphorylation of STAT3 in response to a 15-min pulse of IL-6 was extended until at least 90 min, with low level phosphorylation also apparent at later time points (Fig. 7A).”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Tyrosine phosphorylation of STAT proteins is a valid measure of cytokine signaling and desensitization.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    Three groups of genes with variable expression profiles were identified by GeneCluster2.

    “Three groups of genes with variable expression profiles were also identified by GeneCluster2 (data not shown).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    IL-6 induced both Socs1 and Socs3 mRNA to a similar extent, but more SOCS3 protein than SOCS1 protein.

    “IL-6 induced both Socs1 and Socs3 mRNA to a similar extent, but more SOCS3 protein than SOCS1 protein”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Socs3 mRNA expression was rapidly reduced after 30 min, with minimal expression between 60 to 90 min, and re-established by 180 min.

    “This was followed by a rapid reduction of Socs3 mRNA expression, with minimal expression observed between 60 to 90 min, and subsequent re-establishment of expression by 180 min.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Socs1 mRNA and SOCS1 protein were induced to a greater extent by IFNγ than by IL-6, whereas Socs3 mRNA and SOCS3 protein were induced more by IL-6 than by IFNγ.

    “Socs1 mRNA and SOCS1 protein were induced to a greater extent by IFN␥ than by IL-6, whereas Socs3 mRNA and SOCS3 protein were induced more by IL-6 than by IFN␥.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Socs1 mRNA expression was induced slowly, but remained at near-maximal levels from 60 min until at least 480 min.

    “expression of Socs1 mRNA was induced slowly, but remained at near-maximal levels from 60 min until at least 480 min.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    Several genes in the variable-expression groups were later determined by Q-PCR to be regulated in the liver with high variability and not specifically in response to IFNγ.

    “Several of the genes included in these groups were later determined by Q-PCR analysis to be regulated in the liver with a high degree of variability and not specifically in response to IFN␥ (data not shown).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    IL-6 induced expression of SOCS3 protein very rapidly, with maximal levels detected 30 min to 1 h following injection, at a time that correlates with a decline in STAT1/STAT3 tyrosine phosphorylation.

    “IL-6 induced the expression of SOCS3 protein very rapidly, with maximal levels detected 30 min to 1 h following injection, at a time that correlates with a decline in STAT1/STAT3 tyrosine phosphorylation (Fig. 1D; compare with Fig. 1, A and B)”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingnone given

    Despite rapid phosphorylation of STAT1, induction of Socs1 mRNA was slow.

    “Yet despite the rapid phosphorylation of STAT1, the induction of Socs1 mRNA was slow.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: Tyrosine phosphorylation of STAT proteins is a valid measure of cytokine signaling and desensitization.

  • May combine two claims.

    Findingown data

    The first phase of STAT3 phosphorylation occurred between 15 and 30 min, and the second from 120 min onward.

    “The first phase occurred between 15 and 30 min, and the second from 120 min onward.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    IFNγ induced Socs1 to greater levels than did IL-6, whereas IL-6 induced Socs3 to greater levels than did IFNγ.

    “Again, IFN␥ induced Socs1 to greater levels than did IL-6, whereas IL-6 induced Socs3 to greater levels than did IFN␥.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    SOCS1 protein expression was maintained at a high level for at least 8 h, and declined to near basal levels by 16 h.

    “SOCS1 protein expression was maintained at a high level for at least 8 h, and declined to near basal levels by 16 h.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    In C57BL/6 bone marrow-derived macrophages, regulation of continuous IL-6 signaling by SOCS3 was bi-phasic, with the first peak of IL-6 signaling appearing rapidly and transiently.

    “In C57BL/6 bone marrow-derived macrophages, regulation of continuous IL-6-signaling by SOCS3 was bi-phasic, with the first peak of IL-6 signaling appearing rapidly and transiently.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    IFNγ induced robust expression of SOCS1 protein, with levels reaching maximum at 2-4 h after injection, at a time when STAT1 and STAT3 phosphorylation was waning.

    “IFN␥ induced the robust expression of SOCS1 protein, with levels reaching a maximum at 2-4 h after injection of IFN␥, at a time when STAT1 and STAT3 phosphorylation was waning (Fig. 1C; compare with Fig. 1, A and B).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Limited desensitization to IL-6 was apparent for all re-stimulated Socs3-deficient cells and was more pronounced at later time points.

    “Limited desensitization to IL-6 was, however, apparent for all re-stimulated Socs3-deficient cells, and was more pronounced at later time points”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Tyrosine phosphorylation of STAT proteins is a valid measure of cytokine signaling and desensitization.

  • May combine two claims.

    Findingown data

    The decline in STAT3 phosphorylation from the initial peak at 15 min was rapid, and near-basal P-STAT3 levels were achieved by 60 min.

    “The decline in STAT3 phosphorylation from the initial peak at 15 min was rapid, and near-basal P-STAT3 levels were achieved by 60 min”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Prolonged IFNγ signaling resulted in high levels of Socs1 mRNA expression and low levels of STAT1 tyrosine phosphorylation.

    “Surprisingly, prolonged IFN␥ signaling resulted in high levels of Socs1 mRNA expression, and low levels of STAT1 tyrosine phosphorylation.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    After prolonged IL-6 signaling, medium levels of STAT3 activation, Socs3 mRNA expression, and presumably SOCS3 protein expression were observed.

    “After prolonged IL-6 signaling, medium levels of STAT3 activation, Socs3 mRNA expression, and presumably SOCS3 protein expression were observed.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    More than 95% of the cultured cells used were macrophages, as determined by morphology.

    “Cells, of which more than 95% were macrophages (as determined by morphology), were then plated into 12-well tissue culturetreated plates (5 ϫ 10 5 cells/well) and incubated at 37 °C, 10% CO 2 .”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Mice conditionally deficient for Socs3 revealed SOCS3 to be a potent physiological suppressor of IL-6 but not IFNγ signaling.

    “the generation of mice conditionally deficient for Socs3 revealed SOCS3 to be a potent physiological suppressor of IL-6 but not IFN␥ signaling (24 -26).”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [24] Croker, 2003, Nat. Immunol. source
    • cites [25] Lang, 2003, Nat. Immunol. source
    • cites [26] Yasukawa, 2003, Nat. Immunol. source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    Changing the parameters specifying the number of clusters recognized by GeneCluster2 made little difference to the relationships observed between the responses to IFNγ of livers from Ifnγ-/- Socs1-/- and Ifnγ-/- mice.

    “Importantly, changing the parameters specifying the number of clusters recognized by GeneCluster2 made little difference to the relationships observed between the responses to IFN␥ of livers from Ifn␥ Ϫ/Ϫ Socs1 Ϫ/Ϫ and Ifn␥ Ϫ/Ϫ mice.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Physiologically, SOCS1 is the main inducible inhibitor of IFNγ signaling and in neonatal mice prevents establishment of a lethal inflammatory disease characterized by heightened circulating IFNγ, fatty degeneration of the liver, and necrosis of the liver and other organs.

    “Physiologically, SOCS1 is the main inducible inhibitor of IFN␥ signaling and in neonatal mice prevents the establishment of a lethal inflammatory disease characterized by heightened levels of circulating IFN␥, fatty degeneration of the liver, and necrosis of the liver and other organs (22).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [22] Alexander, 1999, Cell source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Signaling by IL-6 and IFNγ begins at the cell surface where the cytokines associate with their respective receptor complexes.

    “Signaling by IL-6 and IFN␥ begins at the surface of the cell where the cytokines associate with their respective receptor complexes (1).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [1] Nicola, 1994

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationcitation

    The differences in phosphorylation of STAT1 and STAT3 by IFNγ and IL-6 are consistent with the role of STAT1 as an important mediator of the response to IFNγ and the role of STAT3 as an important mediator of the response to IL-6.

    “These differences in the phosphorylation of STAT1 and STAT3 by IFN␥ and IL-6 are consistent with the role of STAT1 as an important mediator of the response to IFN␥ and the role of STAT3 as an important mediator of the response to IL-6 (21).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [21] Ihle, 2001, Curr. Opin. Cell Biol. source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    It is uncertain whether expression of genes grouped into cluster C is prolonged in the absence of SOCS1 because sufficient discriminatory time points were not available.

    “it is uncertain whether the same is true for the genes grouped into cluster C, because sufficient discriminatory time points were not available.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    The macrophage results seem to differ from the response to injection of IFNγ in whole livers, probably because livers were taken from mice subjected to a single stimulation of IFNγ, whereas IFNγ signaling in bone marrow-derived macrophages was continuous.

    “These results seem to differ from the response to injection of IFN␥ that is observed in whole livers (Fig. 1, B and E), probably because the livers were taken from mice subjected to a single stimulation of IFN␥, whereas IFN␥ signaling in the bone marrowderived macrophages was continuous.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    Loss of Socs3 results in prolonged expression of genes normally induced by IL-6 at early time points and heightened and uniform expression of genes normally induced by IL-6 with bi-phasic kinetics.

    “These results suggest that loss of Socs3 results in the prolonged expression of genes that are normally induced by IL-6 at early time points and in the heightened and uniform expression of genes that are normally induced by IL-6 with bi-phasic kinetics.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    Only a single liver was used for each time point in the microarray analysis.

    “While only a single liver was used for each time point, differential expression was defined as relative induction or suppression of expression over at least two consecutive time points.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    Both SOCS3 and SOCS1 desensitized bone marrow-derived macrophages to signaling by IL-6 and IFNγ, respectively, with the activity of SOCS1 occurring later than the activity of SOCS3.

    “We demonstrated that both SOCS3 and SOCS1 desensitized bone marrow-derived macrophages to signaling by IL-6 and IFN␥, respectively, with the activity of SOCS1 occurring later than the activity of SOCS3.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Tyrosine phosphorylation of STAT proteins is a valid measure of cytokine signaling and desensitization.

  • May combine two claims.

    Interpretationown data

    IFNγ appears to induce SOCS1 protein expression relatively slowly, leading to slow inhibition and desensitization of signaling.

    “IFN␥ appears to induce SOCS1 protein expression relatively slowly, leading to slow inhibition and desensitization of signaling.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Tyrosine phosphorylation of STAT proteins is a valid measure of cytokine signaling and desensitization.

  • May combine two claims.

    Interpretationreasoning

    IL-6 appears to induce SOCS3 protein expression rapidly, resulting in bi-phasic IL-6 signaling and relatively rapid desensitization.

    “In contrast, IL-6 appears to induce SOCS3 protein expression rapidly, resulting in bi-phasic IL-6 signaling, and relatively rapid desensitization.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Tyrosine phosphorylation of STAT proteins is a valid measure of cytokine signaling and desensitization.

  • May combine two claims.

    Interpretationown data

    Both SOCS1 and SOCS3 are able to desensitize cells to signaling by IFNγ and IL-6, respectively.

    “In conclusion, both SOCS1 and SOCS3 are able to desensitize cells to signaling by IFN␥ and IL-6, respectively.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Tyrosine phosphorylation of STAT proteins is a valid measure of cytokine signaling and desensitization.
47 of 47

  • The paper relies on this without support.

    Tyrosine phosphorylation of STAT proteins is a valid measure of cytokine signaling and desensitization.

    “Desensitization of Ifn␥ Ϫ/Ϫ macrophages (as measured by STAT1 tyrosine phosphorylation) following 15 min of IFN␥ signaling was observed after 120 min and until 360 min (Fig. 8B).”

  • The paper relies on this without support.

    Little is known about the comparative induction of SOCS proteins by IFNγ and IL-6.

    “however little is known of the comparative induction of SOCS proteins by IFN␥ and IL-6.”
2 of 2

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • SOCS3 mRNA peak is placed at two different times

    Minor

    The results state that Socs3 mRNA expression was maximal at 30 min, whereas the kinetic model places maximal induction after approximately 1 h.

  • Second phase of IL-6 signaling begins at conflicting times

    Minor

    The results place the second phase of STAT3 phosphorylation at 120 min onward, but the kinetic model says IL-6 signaling resumes after 3 h.

2 of 2

Cites

Flagged first, then by citations

Research works printed but not linked: 2

  1. Sims, 1993, Mol. Cell Biol., 13, 690
  2. Nakajima, 1991, Mol. Cell Biol., 11, 1409

Cited by

Sorted by citations

Related

Authors
Wormald, S., Zhang, J.-G., Krebs, D. L., Mielke, L. A., Silver, J., Alexander, W. S., Speed, T. P., Nicola, N. A., & Hilton, D. J.
Affiliations
Walter and Eliza Hall Institute of Medical Research (AU)
Corresponding author
Wormald, Samuel
ORCID
Venue
Journal of Biological Chemistry
Publisher
Elsevier BV
Published
2006-04
Volume
281
Issue
16
Pages
11135-11143
ISSN
0021-9258 (ISSN-L)
DOI
10.1074/jbc.m509595200
OpenAlex
W2019667607
Cited by
123
References
44
Citations by year
2025: 3 · 2024: 1 · 2023: 2 · 2022: 9 · 2021: 5 · 2020: 3 · 2019: 3 · 2018: 4 · 2017: 8 · 2016: 13 · 2015: 4 · 2014: 3 · 2013: 6 · 2012: 8
FWCI
5.43
Type
journal article
Language
en
Open access
Licence
Locations
  • Journal of Biological Chemistry (publishedVersion, cc-by)
  • PubMed (publishedVersion)
Funders
  • National Institutes of Health (CA22556)
  • National Cancer Institute (CA22556)
Topics
  • Health Sciences › Medicine › Oncology › Cytokine Signaling Pathways and Interactions
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Protein Tyrosine Phosphatases
  • Life Sciences › Immunology and Microbiology › Immunology › interferon and immune responses
Keywords
SOCS1, SOCS3, cytokine signaling, negative feedback, STAT1 tyrosine phosphorylation, STAT3 tyrosine phosphorylation, interferon-gamma signaling, IL-6 signaling, signal transduction kinetics, bone marrow-derived macrophages, liver, gene expression kinetics
MeSH terms
Suppressor of Cytokine Signaling 1 Protein, Suppressor of Cytokine Signaling 3 Protein, Animals, Bone Marrow Cells, Carrier Proteins, Interferon-gamma, Kinetics, Macrophages, Mice, Inbred C57BL, Mice, Transgenic, Phosphorylation, Repressor Proteins, RNA, RNA, Messenger, Time Factors, Tyrosine, Blotting, Western, Signal Transduction, Interleukin-6, Cluster Analysis, Polymerase Chain Reaction, Cytokines, DNA, Complementary, Reverse Transcriptase Polymerase Chain Reaction, Oligonucleotide Array Sequence Analysis, Immunoprecipitation, Suppressor of Cytokine Signaling Proteins, Mice

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-23.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-23.

Cited sources are checked by gpt-6-sol.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review