Biological activity differences between TGF-β1 and TGF-β3 correlate with differences in the rigidity and arrangement of their component monomers

[Image: see text] TGF-β1, -β2, and -β3 are small, secreted signaling proteins. They share 71–80% sequence identity and signal through the same receptors, yet the isoform-specific null mice have distinctive phenotypes and are inviable. The replacement of the coding sequence of TGF-β1 with TGF-β3 and TGF-β3 with TGF-β1 led to only partial rescue of the mutant phenotypes, suggesting that intrinsic differences between them contribute to the requirement of each in vivo. Here, we investigated whether the previously reported differences in the flexibility of the interfacial helix and arrangement of monomers was responsible for the differences in activity by generating two chimeric proteins in which residues 54–75 in the homodimer interface were swapped. Structural analysis of these using NMR and functional analysis using a dermal fibroblast migration assay showed that swapping the interfacial region swapped both the conformational preferences and activity. Conformational and activity differences were also observed between TGF-β3 and a variant with four helix-stabilizing residues from TGF-β1, suggesting that the observed changes were due to increased helical stability and the altered conformation, as proposed. Surface plasmon resonance analysis showed that TGF-β1, TGF-β3, and variants bound the type II signaling receptor, TβRII, nearly identically, but had small differences in the dissociation rate constant for recruitment of the type I signaling receptor, TβRI. However, the latter did not correlate with conformational preference or activity. Hence, the difference in activity arises from differences in their conformations, not their manner of receptor binding, suggesting that a matrix protein that differentially binds them might determine their distinct activities

A structurally distinct TGF-β mimic from an intestinal helminth parasite potently induces regulatory T cells.

Helminth parasites defy immune exclusion through sophisticated evasion mechanisms, including activation of host immunosuppressive regulatory T (Treg) cells. The mouse parasite Heligmosomoides polygyrus can expand the host Treg population by secreting products that activate TGF-β signalling, but the identity of the active molecule is unknown. Here we identify an H. polygyrus TGF-β mimic (Hp-TGM) that replicates the biological and functional properties of TGF-β, including binding to mammalian TGF-β receptors and inducing mouse and human Foxp3+ Treg cells. Hp-TGM has no homology with mammalian TGF-β or other members of the TGF-β family, but is a member of the complement control protein superfamily. Thus, our data indicate that through convergent evolution, the parasite has acquired a protein with cytokine-like function that is able to exploit an endogenous pathway of immunoregulation in the host

Change in Structure, Phase Composition, and Properties during Soft Hardening of Titanium Alloy VST5553

Методами оптической, растровой, просвечивающей, ориентационной электронной микроскопии, рентгенографии, МРСА, микроиндентирования рассмотрены особенности формирования структурно-фазового состояния, текстуры и свойств (твердости, модуля упругости) в высокопрочном титановом сплаве VST5553 после мягкой закалки на воздухе при температуре нагрева в b‑ и (a+b)-областях.The features of the formation of the structural-phase state, texture and properties (hardness, contact elastic modulus) in the high-strength titanium alloy VST5553 after soft quenching in air with heating temperatures in b- and (a+b) -areas.Работа выполнена в рамках государственного задания Минобрнауки (№ 0836-2020-0020).The work was carried out within the framework of the state task of the Ministry of Education and Science (№ 0836–2020–0020)

STRUCTURAL AND PHASE TRANSFORMATION IN A COLD-WORKED TITANIUM ALLOY VT22 DURING AGING

The change of structure, phase composition and properties during aging in bars of alloy VT22, pre-hardened from b‑ or (a+b)-region and cold deformed with different degrees of compression, was studied by methods of SEM, х‑ray diffraction analysis and microdurometry.Методами РЭМ, РСФА и микродюрометрии изучено изменение структуры, фазового состава и свойств при старении в прутках из сплава ВТ22, предварительно закаленных из b‑ или (a+b)-области и холоднодеформированных с различными степенями обжатия.Исследование выполнено за счет гранта Российского научного фонда (проект № 18-13-00220)

CHANGE IN SIZE OF β -GRAIN DURING HEATING IN THE HIGH-STRENGTH TITANIUM ALLOYS WITH DIFFERENT INITIAL STRUCTURE

Методами структурного анализа изучено изменение зеренной структуры в титановом сплаве ВТ22 с исходной структурой, полученной деформацией в двухфазной α+β- и однофазной β-области, в интервале температур нагрева 845–1250°С. Показано, что в сплаве, деформированном в двухфазной области, наблюдается активный рост β-зерна при температурах нагрева свыше 900°С, а в сплаве, деформированном в β-области, размер исходного β-зерна мало меняется вплоть до максимальной температуры нагрева.The changes in the grain structure of the titanium alloy VT22 with the original structure, resulting in deformation of the two-phase (α+β-) and single-phase β-field, in the range 845–1250 °C heating temperatures was investigated by methods of structural analysis. It is shown that the alloy deformed in α+β- field there is strong grain growth β -heating at temperatures in excess of 900 °C, and an alloy in β-deformed area, the size of the original β-grains varies little to the heating temperature up to 1200 °C.Работа выполнена при поддержке проекта № 2329, выполняемого в рамках базовой части госзадания 236/2014 Минобрнауки РФ

Identification of the Rheumatoid Arthritis Shared Epitope Binding Site on Calreticulin

Background: The rheumatoid arthritis (RA) shared epitope (SE), a major risk factor for severe disease, is a five amino acid motif in the third allelic hypervariable region of the HLA-DRb chain. The molecular mechanisms by which the SE affects susceptibility to – and severity of- RA are unknown. We have recently demonstrated that the SE acts as a ligand that interacts with cell surface calreticulin (CRT) and activates innate immune signaling. In order to better understand the molecular basis of SE-RA association, here we have undertaken to map the SE binding site on CRT. Principal Findings: Surface plasmon resonance (SPR) experiments with domain deletion mutants suggested that the SE binding site is located in the P-domain of CRT. The role of this domain as a SE-binding region was further confirmed by a sulfosuccinimidyl-2-[6-(biotinamido)-2-(p-azido-benzamido) hexanoamido] ethyl-1,3-dithiopropionate (sulfo-SBED) photoactive cross-linking method. In silico analysis of docking interactions between a conformationally intact SE ligand and the CRT P-domain predicted the region within amino acid residues 217–224 as a potential SE binding site. Site-directed mutagenesis demonstrated involvement of residues Glu 217 and Glu 223- and to a lesser extent residue Asp 220- in cell-free SPR-based binding and signal transduction assays. Significance: We have characterized here the molecular basis of a novel ligand-receptor interaction between the SE and CRT. The interaction represents a structurally and functionally well-defined example of cross talk between the adaptive an

Клеточные технологии в лечении заболеваний сетчатки

The article analyzes the experience of cellular technology application in the treatment of retinal degenerative diseases. Experimental studies proved the ability of stem cells for self-renewal, migration, integration and subsequent differentiation into most types of retinal nerve cells, including photoreceptors. The article describes the experience of application and complications arising from the application of the following types of stem cells: retinal pigment epithelium cells, neural stem cells, mesenchymal stem cells, bone marrow cells, cord blood stem cells, induced pluripotent stem cells. Main mechanisms of cells action are discussed, namely replacement therapy and paracrine effect. The article marks the role of stem cells in the induction of angiogenesis, suppressing the local inflammatory response and apoptosis. In conclusion, the author describes the use of hematopoietic stem cells of human umbilical cord blood for restoring visual impairment in patients with normotensive glaucoma.В статье проанализирован опыт применения клеточных технологий в лечении дегенеративных заболеваний сетчатки. В экспериментальных исследованиях доказана способность стволовых клеток к самообновлению, миграции, интеграции и последующей диф-ференцировке в большинство типов нервных клеток сетчатки, включая фоторецепторные. Описан опыт применения и осложнения, возникающие при применении следующих видов стволовых клеток: клеток пигментного эпителия, нейрональных стволовых клеток, мезенхимальных стволовые клеток, клеток костного мозга, стволовых клеток пуповинной крови, индуцированных плюрипотентных стволовых клеток. Обсуждаются основные механизмы действия клеток, а именно: замещающая терапия и паракринный эффект. Отмечена роль стволовых клеток в индукции ангиогенеза, подавлении местной воспалительной реакции и апоптоза. В заключении авторами описывается методика применения гемопоэтических клеток пуповинной крови человека для восстановления нарушений зрения при нормотензивной глаукоме

Activation of the B cell receptor leads to increased membrane proximity of the Igα cytoplasmic domain.

Binding of antigen to the B cell receptor (BCR) induces conformational changes in BCR's cytoplasmic domains that are concomitant with phosphorylation of the immunoreceptor tyrosine-based activation motifs (ITAMs). Recently, reversible folding of the CD3ε and ξ chain ITAMs into the plasma membrane has been suggested to regulate T cell receptor signaling. Here we show that the Igα and Igβ cytoplasmic domains of the BCR do not associate with plasma membrane in resting B cells. However, antigen binding and ITAM phosphorylation specifically increased membrane proximity of Igα, but not Igβ. Thus, BCR activation is accompanied by asymmetric conformational changes, possibly promoting the binding of Igα and Igβ to differently localized signaling complexes

Evidence for a Two-Metal-Ion Mechanism in the Cytidyltransferase KdsB, an Enzyme Involved in Lipopolysaccharide Biosynthesis

Lipopolysaccharide (LPS) is located on the surface of Gram-negative bacteria and is responsible for maintaining outer membrane stability, which is a prerequisite for cell survival. Furthermore, it represents an important barrier against hostile environmental factors such as antimicrobial peptides and the complement cascade during Gram-negative infections. The sugar 3-deoxy-d-manno-oct-2-ulosonic acid (Kdo) is an integral part of LPS and plays a key role in LPS functionality. Prior to its incorporation into the LPS molecule, Kdo has to be activated by the CMP-Kdo synthetase (CKS). Based on the presence of a single Mg2+ ion in the active site, detailed models of the reaction mechanism of CKS have been developed previously. Recently, a two-metal-ion hypothesis suggested the involvement of two Mg2+ ions in Kdo activation. To further investigate the mechanistic aspects of Kdo activation, we kinetically characterized the CKS from the hyperthermophilic organism Aquifex aeolicus. In addition, we determined the crystal structure of this enzyme at a resolution of 2.10 Å and provide evidence that two Mg2+ ions are part of the active site of the enzyme