The TGF-β mimic TGM4 achieves cell specificity through combinatorial surface co-receptor binding.
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus (mouse)
SUBMITTER:
PROVIDER: S-BSST1623 | biostudies-other |
REPOSITORIES: biostudies-other
Similar Datasets
Project description:The murine helminth parasite Heligmosomoides polygyrus expresses a family of modular proteins which, replicating the functional activity of the immunomodulatory cytokine TGF-β, have been named TGM (TGF-β Μimic). Multiple domains bind to different receptors, including TGF-β receptors TβRI (ALK5) and TβRII through domains 1-3, and prototypic family member TGM1 binds the cell surface co-receptor CD44 through domains 4-5. This allows TGM1 to induce T lymphocyte Foxp3 expression, characteristic of regulatory (Treg) cells, and to activate a range of TGF-β-responsive cell types. In contrast, a related protein, TGM4, targets a much more restricted cell repertoire, primarily acting on myeloid cells, with less potent effects on T cells and lacking activity on other TGF-β-responsive cell types. TGM4 binds avidly to myeloid cells by flow cytometry, and can outcompete TGM1 for cell binding. Analysis of receptor binding in comparison to TGM1 reveals a 10-fold higher affinity than TGM1 for TGFβR-I (TβRI), but a 100-fold lower affinity for TβRII through Domain 3. Consequently, TGM4 is more dependent on co-receptor binding; in addition to CD44, TGM4 also engages CD49d (Itga4) through Domains 1-3, as well as CD206 and Neuropilin-1 through Domains 4 and 5. TGM4 was found to effectively modulate macrophage populations, inhibiting lipopolysaccharide-driven inflammatory cytokine production and boosting interleukin (IL)-4-stimulated responses such as Arginase-1 in vitro and in vivo. These results reveal that the modular nature of TGMs has allowed the fine tuning of the binding affinities of the TβR- and co-receptor binding domains to establish cell specificity for TGF-β signalling in a manner that cannot be attained by the mammalian cytokine.
2024-11-15 | PXD048278 | Pride
Project description:Transforming growth factor (TGF)-betas are secreted in large latent complexes consisting of TGF-beta, its N-terminal latency-associated peptide (LAP) propeptide, and latent TGF-beta binding protein (LTBP). LTBPs are required for secretion and subsequent deposition of TGF-beta into the extracellular matrix. TGF-beta1 associates with the 3(rd) 8-Cys repeat of LTBP-1 by LAP. All LTBPs, as well as fibrillins, contain multiple 8-Cys repeats. We analyzed the abilities of fibrillins and LTBPs to bind latent TGF-beta by their 8-Cys repeats. 8-Cys repeat was found to interact with TGF-beta1*LAP by direct cysteine bridging. LTBP-1 and LTBP-3 bound efficiently all TGF-beta isoforms, LTBP-4 had a much weaker binding capacity, whereas LTBP-2 as well as fibrillins -1 and -2 were negative. A short, specific TGF-beta binding motif was identified in the TGF-beta binding 8-Cys repeats. Deletion of this motif in the 3(rd) 8-Cys repeat of LTBP-1 resulted in loss of TGF-beta*LAP binding ability, while its inclusion in non-TGF-beta binding 3(rd) 8-Cys repeat of LTBP-2 resulted in TGF-beta binding. Molecular modeling of the 8-Cys repeats revealed a hydrophobic interaction surface and lack of three stabilizing hydrogen bonds introduced by the TGF-beta binding motif necessary for the formation of the TGF-beta*LAP - 8-Cys repeat complex inside the cells.
| S-EPMC14949 | biostudies-literature
Project description:Transforming growth factor-beta (TGF-beta) superfamily members play an important role in growth, differentiation, adhesion, apoptosis, and development in many species from insects and worms to vertebrates. Recently, TGF-beta signaling has been demonstrated to be negatively regulated by microtubules (MTs), which anchor endogenous Smad2/3 to cytosol and also directly interact with connexin43 (Cx43), and the activity of TGF-beta is mediated by Cx43. However, the mechanism underlying the intracellular regulation of TGF-beta activity by Cx43 remains unknown. Here, we found that the functional link between TGF-beta activation and Cx43 is mediated by interactions among Smad2/3, MTs, and Cx43. We confirmed that Cx43 competes with Smad2/3 for binding to MTs, which Cx43 specifically induces release of Smad2/3 from MTs and increases phospho-Smad2 and which, as a result, Smad2/3 and Smad4 are accumulated in the nucleus, leading to activation of the transcription of target genes. Consistently, knockdown of the endogenous Cx43 activity with double-strand RNA (dsRNA) in HL1 cardiomyocytes and Cx43 knockout mice cardiomyocytes consistently show the opposite effect. Our findings demonstrate a novel mechanism for Cx43 positive regulation of TGF-beta function.
| S-EPMC1877122 | biostudies-literature
Project description:The vertebrate homologues of Drosophila dachsund, DACH1 and DACH2, have been implicated as important regulatory genes in development. DACH1 plays a role in retinal and pituitary precursor cell proliferation and DACH2 plays a specific role in myogenesis. DACH proteins contain a domain (DS-domain) that is conserved with the proto-oncogenes Ski and Sno. Since the Ski/Sno proto-oncogenes repress AP-1 and SMAD signaling, we hypothesized that DACH1 might play a similar cellular function. Herein, DACH1 was found to be expressed in breast cancer cell lines and to inhibit TGF-beta induced apoptosis. DACH1 repressed TGF-beta induction of AP-1 and Smad signaling in gene reporter assays and repressed endogenous TGF-beta responsive genes by microarray analyses. DACH1 bound to endogenous NCoR and Smad4 in cultured cells and DACH1 co-localized with NCoR in nuclear dot-like structures. NCoR enhanced DACH1 repression and the repression of TGF-beta-induced AP-1 or Smad-signaling by DACH1 required the DACH1 DS domain. The DS-domain of DACH was sufficient for NCoR-binding at a Smad4-binding site. Smad4 was required for DACH1 repression of Smad signaling. In Smad4 null HTB-134 cells, DACH1 inhibited the activation of SBE-4 reporter activity induced by Smad2 or Smad3 only in the presence of Smad4. DACH1 participates in the negative regulation of TGF-beta signaling by interacting with NCoR and Smad4. Keywords: other
2003-10-15 | GSE685 | GEO
Project description:How transcription factor dimerization impacts DNA-binding specificity is poorly understood. Guided by protein dimerization properties, we examined DNA binding specificities of 270 human bZIP pairs. DNA interactomes of 80 heterodimers and 22 homodimers revealed that 72% of heterodimer motifs correspond to conjoined half-sites preferred by partnering monomers. Remarkably, the remaining motifs are composed of variably-spaced half-sites (12%) or 'emergent' sites (16%) that cannot be readily inferred from half-site preferences of partnering monomers. These binding sites were biochemically validated by EMSA-FRET analysis and validated in vivo by ChIP-seq data from human cell lines. Focusing on ATF3, we observed distinct cognate site preferences conferred by different bZIP partners, and demonstrated that genome-wide binding of ATF3 is best explained by considering many dimers in which it participates. Importantly, our compendium of bZIP-DNA interactomes predicted bZIP binding to 156 disease associated SNPs, of which only 20 were previously annotated with known bZIP motifs.
| S-EPMC5349851 | biostudies-literature
Project description:Eight integrin α-β heterodimers recognize ligands with an Arg-Gly-Asp (RGD) motif. However, the structural mechanism by which integrins differentiate among extracellular proteins with RGD motifs is not understood. Here, crystal structures, mutations and peptide-affinity measurements show that αVβ6 binds with high affinity to a RGDLXXL/I motif within the prodomains of TGF-β1 and TGF-β3. The LXXL/I motif forms an amphipathic α-helix that binds in a hydrophobic pocket in the β6 subunit. Elucidation of the basis for ligand binding specificity by the integrin β subunit reveals contributions by three different βI-domain loops, which we designate specificity-determining loops (SDLs) 1, 2 and 3. Variation in a pair of single key residues in SDL1 and SDL3 correlates with the variation of the entire β subunit in integrin evolution, thus suggesting a paradigmatic role in overall β-subunit function.
| S-EPMC4717663 | biostudies-literature
Project description:TGF-beta is a pluripotent cytokine that mediates its effects through a receptor composed of TGF-beta receptor type II (TGFBR2) and type I (TGFBR1). The TGF-beta receptor can regulate Smad and nonSmad signaling pathways, which then ultimately dictate TGF-beta's biological effects. We postulated that control of the level of TGFBR2 is a mechanism for regulating the specificity of TGF-beta signaling pathway activation and TGF-beta's biological effects. We used a precisely regulatable TGFBR2 expression system to assess the effects of TGFBR2 expression levels on signaling and TGF-beta mediated apoptosis. We found Smad signaling and MAPK-ERK signaling activation levels correlate directly with TGFBR2 expression levels. Furthermore, p21 levels and TGF-beta induced apoptosis appear to depend on relatively high TGFBR2 expression and on the activation of the MAPK-ERK and Smad pathways. Thus, control of TGFBR2 expression and the differential activation of TGF-beta signaling pathways appears to be a mechanism for regulating the specificity of the biological effects of TGF-beta.
| S-EPMC2700179 | biostudies-literature
Project description:DACH1 inhibits TGF-beta signaling through binding Smad4
| PRJNA87633 | ENA
Project description:Control over supramolecular recognition between proteins and nanoparticles (NPs) is of fundamental importance in therapeutic applications and sensor development. Most NP-protein binding approaches use 'tags' such as biotin or His-tags to provide high affinity; protein surface recognition provides a versatile alternative strategy. Generating high affinity NP-protein interactions is challenging however, due to dielectric screening at physiological ionic strengths. We report here the co-engineering of nanoparticles and protein to provide high affinity binding. In this strategy, 'supercharged' proteins provide enhanced interfacial electrostatic interactions with complementarily charged nanoparticles, generating high affinity complexes. Significantly, the co-engineered protein-nanoparticle assemblies feature high binding affinity even at physiologically relevant ionic strength conditions. Computational studies identify both hydrophobic and electrostatic interactions as drivers for these high affinity NP-protein complexes.
| S-EPMC8941649 | biostudies-literature
Project description:The mouse intestinal helminth Heligmosomoides polygyrus modulates host immune responses by secreting a transforming growth factor (TGF)-β mimic (TGM), to expand the population of Foxp3+ Tregs. TGM comprises five complement control protein (CCP)-like domains, designated D1-D5. Though lacking homology to TGF-β, TGM binds directly to the TGF-β receptors TβRI and TβRII and stimulates the differentiation of naïve T-cells into Tregs. However, the molecular determinants of binding are unclear. Here, we used surface plasmon resonance, isothermal calorimetry, NMR spectroscopy, and mutagenesis to investigate how TGM binds the TGF-β receptors. We demonstrate that binding is modular, with D1-D2 binding to TβRI and D3 binding to TβRII. D1-D2 and D3 were further shown to compete with TGF-β(TβRII)2 and TGF-β for binding to TβRI and TβRII, respectively. The solution structure of TGM-D3 revealed that TGM adopts a CCP-like fold but is also modified to allow the C-terminal strand to diverge, leading to an expansion of the domain and opening potential interaction surfaces. TGM-D3 also incorporates a long structurally ordered hypervariable loop, adding further potential interaction sites. Through NMR shift perturbations and binding studies of TGM-D3 and TβRII variants, TGM-D3 was shown to occupy the same site of TβRII as bound by TGF-β using both a novel interaction surface and the hypervariable loop. These results, together with the identification of other secreted CCP-like proteins with immunomodulatory activity in H. polygyrus, suggest that TGM is part of a larger family of evolutionarily plastic parasite effector molecules that mediate novel interactions with their host.
| S-EPMC9163516 | biostudies-literature