| 1998 |
TgHSP70 (72 kDa protein) expression is induced during bradyzoite development in T. gondii under alkaline pH stress (pH 8.1), as demonstrated by Western blotting, immunofluorescence, immunoelectron microscopy, and RT-PCR; hsp70 colocalized with bradyzoite-specific antigens and was detected in bradyzoites isolated from mouse brain. Quercetin, which inhibits hsp70 synthesis, suppressed bradyzoite development in vitro. |
Western blot, immunofluorescence, immunoelectron microscopy, RT-PCR, pharmacological inhibition (quercetin) |
Infection and immunity |
Medium |
9632598
|
| 1998 |
The cytoplasmic 70 kDa HSP gene is single-copy in both virulent (RH) and avirulent (ME49) strains; virulent strains have four copies of a 7-aa C-terminal repeat (GGMPGGM) vs. five in avirulent strains, and show 1.5–2-fold higher mRNA transcription in vivo and in vitro, indicating post-transcriptional regulation also occurs in T. gondii. |
Genomic DNA library screening, PCR amplification, gene sequencing, copy-number estimation, Northern/mRNA analysis |
International journal for parasitology |
Medium |
9724875
|
| 1998 |
High-level TgHSP70 expression occurs during in vivo bradyzoite-to-tachyzoite conversion (reactivation) in chronically infected mice treated with neutralizing anti-IFN-γ or anti-TNF-α antibodies, demonstrating HSP70 upregulation is associated with stage conversion under immunosuppressive conditions. |
Immunocytochemistry, photometric assay of antigen expression in CNS tissue |
Infection and immunity |
Low |
9673286
|
| 2002 |
Antisense oligonucleotide-mediated reduction of TgHSP70 expression in virulent T. gondii strains (RH, ENT) increased host NF-κB activation in splenocytes and iNOS/NO production in RAW 264.7 macrophages, and enhanced tachyzoite-to-bradyzoite conversion in vitro; these effects were not observed in avirulent strains (ME49, C), establishing TgHSP70 as a suppressor of host NF-κB and iNOS-mediated killing specifically in virulent strains. |
Antisense oligonucleotide transfection, Western blot (HSP70 expression), in vivo tachyzoite counting (spleen), in vitro bradyzoite conversion assay, iNOS mRNA measurement, NF-κB nuclear translocation assay, NO production assay |
Journal of immunology |
Medium |
12097402
|
| 2000 |
TgHSP70 inhibits nitric oxide release from peritoneal macrophages of T. gondii-infected mice, and high-level TgHSP70 expression correlates with mortality in IFN-γ knockout mice, identifying TgHSP70 as a danger signal that suppresses host macrophage NO production during lethal acute infection. |
NO release assay (peritoneal macrophages), mRNA analysis (RT-PCR for stage markers), in vivo mortality analysis in IFN-γ KO mice |
Cell stress & chaperones |
Low |
11048655
|
| 2002 |
TgHSP70 functions as a B cell mitogen, inducing proliferation of murine B cells (B220+) but not T cells via TLR4; this proliferation is MyD88-independent (unlike LPS-induced proliferation), polymyxin B-insensitive, and absent in TLR4-mutant (C3H/HeJ) and TLR4-/- mice. |
In vitro proliferation assay, cell subset depletion, TLR4-mutant and knockout mice, MyD88-/- mice, polymyxin B inhibition control |
Cell stress & chaperones |
Medium |
12653480
|
| 2004 |
A pH-responsive cis-regulatory element was identified in the T. gondii hsp70 genomic locus upstream region by deletion analysis using β-galactosidase reporter constructs transiently transfected into RH strain T. gondii; GFP reporter constructs stably transfected into T. gondii showed pH-shock-induced GFP expression driven by this element. Gel-shift analysis identified a putative DNA-binding protein interacting with the pH-regulated region. |
Deletion analysis with β-galactosidase reporter, stable transfection with GFP reporter, electrophoretic mobility shift assay (EMSA/gel shift) |
International journal for parasitology |
Medium |
15003494
|
| 2005 |
TgHSP70-induced macrophage NO production signals through TLR2, MyD88, and IRAK4 (not TLR4); however, TgHSP70-induced macrophage tolerance (suppression of NO on restimulation) is mediated through TLR4 and SOCS-1 upregulation, with JNK and IκBα phosphorylation occurring via TLR2 in the absence of TLR4-mediated tolerance. |
NO release assay, gene-knockout mice (TLR2-/-, TLR4-/-, MyD88-/-, IRAK4-/-), polymyxin B control, SOCS-1 expression assay, JNK and IκBα phosphorylation analysis |
Infection and immunity |
Medium |
16040976
|
| 2006 |
TgHSP70 stimulates maturation of murine bone marrow-derived dendritic cells (increased MHC I/II, CD40, CD80, CD86 surface expression; decreased phagocytic ability; increased alloreactive T cell stimulation; IL-12 production; IFN-β mRNA expression) via TLR4 through a MyD88-independent signal transduction cascade; TLR2-/- and MyD88-/- DCs respond normally, but TLR4-/- DCs do not. |
DC maturation surface marker flow cytometry, phagocytosis assay, allostimulation assay, ELISA (IL-12), RT-PCR (IFN-β), TLR-deficient mouse DCs |
Cell stress & chaperones |
Medium |
16572725
|
| 2006 |
TgHSP70 induces lethal anaphylactic reaction in T. gondii-infected mice through an IFN-γ-dependent, IgE-independent pathway involving platelet-activating factor (PAF); splenocytes (not serum) transfer this reactivity, and PAF receptor antagonist rescues mice from the reaction. |
In vivo anaphylaxis model, adoptive transfer (splenocytes vs. serum), IFN-γ KO mice, B cell-deficient mice, PAF receptor antagonist treatment, RT-PCR (PAF acetylhydrolase, IFN-γ mRNA) |
International immunology |
Medium |
16943259
|
| 2008 |
TgHSP70-induced lethal anaphylactic reaction in infected mice is mediated via TLR4/MyD88-dependent (not TRIF-dependent) signaling, activating cPLA2 via p38 and p44/42 MAPK pathways in CD11b+ splenocytes, leading to PAF production; TLR4-/- and MyD88-/- mice are protected from the reaction. |
In vivo anaphylaxis model, TLR4-/-, TLR2-/-, MyD88-/-, TRIF-/- mice, cPLA2 phosphorylation assay, MAPK pathway inhibitors, PAF-AH mRNA expression |
Microbiology and immunology |
Medium |
18667035
|
| 2010 |
In T. gondii-infected host cells (THP-1 macrophages), HSP70 (host-upregulated by infection) binds pro-apoptotic factors AIF and Apaf-1 (but not cytochrome c or procaspase-9) as shown by co-immunoprecipitation, inhibiting mitochondrial apoptosis by preventing AIF and cytochrome c release from mitochondria and suppressing caspase-3 activation in a parasite load-dependent manner. |
Western blot, DNA fragmentation assay, co-immunoprecipitation, caspase-3/7 activity assay, subcellular fractionation |
Parasitology research |
Medium |
20680337
|
| 2011 |
TgSis1 (a T. gondii Hsp40/J-domain protein homologous to yeast Sis1) is a cytosolic chaperone that co-immunoprecipitates with T. gondii Hsp70 and Hsp90, establishing TgHSP70 as part of a cytosolic Hsp40-Hsp70-Hsp90 chaperone complex in the parasite. |
Co-immunoprecipitation, subcellular localization (cytosolic fractionation), structural modeling |
International journal of biological macromolecules |
Low |
22209934
|
| 2020 |
TgHSP70 is required for intracellular multiplication of T. gondii: the Hsp70-selective inhibitor PES (2-phenylethynesulfonamide) attenuates intracellular T. gondii multiplication, confirmed by biotinylated PES binding directly to both host Hsp70 and TgHSP70 (verified by PES binding assay and molecular docking); silencing of host Hsp70 also reduces parasite multiplication, with attenuation linked to disruption of host autophagy. |
Pharmacological inhibition (PES), biotinylated PES binding assay, host Hsp70 siRNA knockdown, molecular docking (TgHsp70 structural analysis), autophagy functional assay |
Biochimica et biophysica acta. Molecular cell research |
Medium |
33157166
|
| 2000 |
Immune factors (IFN-γ, TNF-α, reactive nitrogen intermediates) do not play primary roles in inducing TgHSP70 production in vivo: virulent RH strain tachyzoites from nude, SCID, IFN-γ receptor KO, and TNF receptor KO mice all produced similar levels of HSP70 as immunocompetent mice. |
Western blot analysis of HSP70 in tachyzoites recovered from immunodeficient mice (nude, SCID, IFN-γR KO, TNFR KO) |
International journal for parasitology |
Medium |
11428337
|
| 2014 |
Systemic (serum) detection of TgHSP70 protein depends on parasite killing by the host immune response, while increased TgHSP70 expression in the brain correlates with parasite multiplication rate; dexamethasone-induced immunosuppression decreased systemic TgHSP70 while increasing cerebral parasitism and TgHSP70 brain expression. |
ELISA (serum TgHSP70 and antibody levels), immunohistochemistry (brain TgHSP70), immune complex detection, dexamethasone immunosuppression model, comparison of BALB/c vs C57BL/6 mice |
PloS one |
Low |
24801069
|
| 2023 |
TgHSP70 directly binds TLR4 (demonstrated by molecular docking, localized surface plasmon resonance, and co-immunoprecipitation), and this interaction activates TLR4/NF-κB signaling; coixol disrupts TgHSP70-TLR4 interaction and inhibits downstream iNOS, TNF-α, and HMGB1 overproduction. |
Molecular docking, localized surface plasmon resonance (LSPR), co-immunoprecipitation, ELISA, Western blot, immunofluorescence, qPCR |
International immunopharmacology |
Medium |
36933491
|
| 2000 |
The carboxy-terminal region of TgHSP70 mediates its immunosuppressive/deleterious effect on host protective immunity: immunization with rTgHSP70-full-length or rTgHSP70-C-terminal region increased brain parasite burden after infection, while rTgHSP70-N-terminal region did not. |
Immunization with recombinant protein fragments, quantitative competitive PCR (QC-PCR) for brain parasite load (SAG1 gene) |
The Korean journal of parasitology |
Low |
10905074
|
| 2019 |
Inducible Hsp70 expressed on the membrane of T. gondii-infected dendritic cells and macrophages triggers Hsp70-dependent autophagy in CD40-expressing endothelial cells via beclin 1 and ULK1, restricting T. gondii invasion of neural tissue; this anti-parasitic activity required both CD40 expression in endothelial cells and inducible Hsp70 expression in the infecting leukocytes. |
In vivo infection model (retina and brain parasite load), adoptive transfer of infected monocytes/DCs, genetic knockouts (beclin 1, ULK1), autophagy assay, anti-Hsp70 functional blocking |
Infection and immunity |
Medium |
31109947
|
| 2024 |
When bag1 (HSP30) is knocked out in T. gondii ME49, transcription of HSP70 (along with HSP20, HSP21, HSP40, HSP60, HSP90, and BFD1) is significantly upregulated during early bradyzoite differentiation, indicating that HSP70 participates in a compensatory stress-response network that partially substitutes for BAG1 function in cyst formation. |
CRISPR/Cas9 gene knockout, qPCR (transcriptional analysis of HSP family members), Western blot, in vitro differentiation assay, mouse infection model |
Parasites & vectors |
Low |
39080770
|