Leucine Repeat Research Articles

Characterizing the amyloid core region of the tumor suppressor protein p16INK4a using a limited proteolysis and peptide-based approach

The human tumor suppressor p16INK4a is a small monomeric protein that can form amyloid structures. Formation of p16INK4a amyloid fibrils is induced by oxidation which creates an intermolecular disulfide bond. The conversion into amyloid is associated with a change from an all α-helical structure into β-sheet fibrils. Currently, structural insights into p16INK4a amyloid fibrils are lacking. Here, we investigate the amyloid-forming regions of this tumor suppressor using isotope-labeling limited-digestion mass spectrometry analysis. We discover two key regions that likely form the structured core of the amyloid. Further investigations using thioflavin-T fluorescence assays, electron microscopy and solution nuclear magnetic resonance spectroscopy of shorter peptide regions confirm the self-assembly of the identified sequences that include methionine and leucine repeat regions. This work describes a simple approach for studying protein motifs involved in the conversion of monomeric species into aggregated fibril structures. It provides first insights into the polypeptide sequence underlying the core structure of amyloid p16INK4a formed after a unique oxidation-driven structural transition.

Osteogenesis imperfecta type 10 and the cellular scaffolds underlying common immunological diseases.

Osteogenesis imperfecta type 10 (OI10) is caused by loss of function codon variants in the gene SERPINH1 that encodes heat shock protein 47 (HSP47), rather than in a gene specifying bone formation. The HSP47 variants disrupt the folding of both collagen and the endonuclease IRE1α (inositol-requiring enzyme 1α) that splices X-Box Binding Protein 1 (XBP1) mRNA. Besides impairing bone development, variants likely affect osteoclast differentiation. Three distinct biochemical scaffold play key roles in the differentiation and regulated cell death of osteoclasts. These scaffolds consist of non-templated protein modifications, ordered lipid arrays, and protein filaments. The scaffold components are specified genetically, but assemble in response to extracellular perturbagens, pathogens, and left-handed Z-RNA helices encoded genomically by flipons. The outcomes depend on interactions between RIPK1, RIPK3, TRIF, and ZBP1 through short interaction motifs called RHIMs. The causal HSP47 nonsynonymous substitutions occur in a novel variant leucine repeat region (vLRR) that are distantly related to RHIMs. Other vLRR protein variants are causal for a variety of different mendelian diseases. The same scaffolds that drive mendelian pathology are associated with many other complex disease outcomes. Their assembly is triggered dynamically by flipons and other context-specific switches rather than by causal, mendelian, codon variants.

Codon Pattern and Context Analysis in Genes Triggering Alzheimer's Disease and Latent Tau Protein Aggregation Post-Anesthesia Exhibited Unique Molecular Patterns Associated with Functional Aspects.

Previous reports have demonstrated post-operative dementia and Alzheimer's disease (AD), and increased amyloid-β levels and tau hyperphosphorylation have been observed in animal models post-anesthesia. After surgical interventions, loss in memory has been observed that has been found linked with genes modulated after anesthesia. Present study aimed to study molecular pattern present in genes modulated post anesthesia and involved in characters progressing towards AD. In the present study, 17 transcript variants belonging to eight genes, which have been found to modulate post-anesthesia and contribute to AD progression, were envisaged for their compositional features, molecular patterns, and codon and codon context-associated studies. The sequences' composition was G/C rich, influencing dinucleotide preference, codon preference, codon usage, and codon context. The G/C nucleotides being highly occurring nucleotides, CpGdinucleotides were also preferred; however, CpG was highly disfavored at p3-1 at the codon junction. The nucleotide composition of Cytosine exhibited a unique feature, and unlike other nucleotides, it did not correlate with codon bias. Contrarily, it correlated with the sequence lengths. The sequences were leucine-rich, and multiple leucine repeats were present, exhibiting the functional role of neuroprotection from neuroinflammation post-anesthesia. The analysis pave the way to elucidate unique molecular patterns in genes modulated during anesthetic treatment and might help ameliorate the ill effects of anesthetics in the future.

Leucine rich-repeat sequence and the related protein in glioma

Leucine rich-repeat sequence (LRR sequence) is a special class of polypeptide sequences composed of several adjacent leucine residues. LRR sequence participates in evolution between species and across species. This sequence is widespread in a variety of proteins and has important biological functions. LRR protein plays a major part in the development of the nervous system and the maintenance of normal function. In addition, a large number of leucine repeats are closely related to the occurrence of a variety of diseases, such as leucine-rich repeat disease, leucine-rich peptide aggregate. Most importantly, it correlates with the development of brain tumors like glioma. This article is primarily focused on the structure and function of LRR sequence and the associated LRR proteins. Moreover, we summary the LRR-contain transmembrane proteins in nerve system and highlight the function of these proteins in glioma progression which takes the sequencing of LRR a potential personalized diagnosis and treatment of brain tumors.

The Hypersensitive Response to Plant Viruses.

Plant proteins with domains rich in leucine repeats play important roles in detecting pathogens and triggering defense reactions, both at the cellular surface for pattern-triggered immunity and in the cell to ensure effector-triggered immunity. As intracellular parasites, viruses are mostly detected intracellularly by proteins with a nucleotide binding site and leucine-rich repeats but receptor-like kinases with leucine-rich repeats, known to localize at the cell surface, have also been involved in response to viruses. In the present review we report on the progress that has been achieved in the last decade on the role of these leucine-rich proteins in antiviral immunity, with a special focus on our current understanding of the hypersensitive response.

HIV-1 reverse transcriptase stability correlates with Gag cleavage efficiency: reverse transcriptase interaction implications for modulating protease activation.

Proteolytic processing of human immunodeficiency virus type 1 particles mediated by viral protease (PR) is essential for acquiring virus infectivity. Activation of PR embedded in Gag-Pol is triggered by Gag-Pol dimerization during virus assembly. We previously reported that amino acid substitutions at the RT tryptophan repeat motif destabilize virus-associated RT and attenuate the ability of efavirenz (EFV, an RT dimerization enhancer) to increase PR-mediated Gag cleavage efficiency. Furthermore, a single amino acid change at RT significantly reduces virus yields due to enhanced Gag cleavage. These data raise the possibility of the RT domain contributing to PR activation by promoting Gag-Pol dimerization. To test this hypothesis, we investigated the putative involvement of a hydrophobic leucine repeat motif (LRM) spanning RT L282 to L310 in RT/RT interactions. We found that LRM amino acid substitutions led to RT instability and that RT is consequently susceptible to degradation by PR. The LRM mutants exhibited reduced Gag cleavage efficiencies while attenuating the EFV enhancement of Gag cleavage. In addition, an RT dimerization-defective mutant, W401A, reduced enhanced Gag cleavage via a leucine zipper (LZ) motif inserted at the deleted Gag-Pol region. Importantly, the presence of RT and integrase domains failed to counteract the LZ enhancement of Gag cleavage. A combination of the Gag cleavage enhancement factors EFV and W402A markedly impaired Gag cleavage, indicating a disruption of W402A Gag-Pol dimerization following EFV binding to W402A Gag-Pol. Our results support the idea that RT modulates PR activation by affecting Gag-Pol/Gag-Pol interaction. IMPORTANCE A stable reverse transcriptase (RT) p66/51 heterodimer is required for HIV-1 genome replication in host cells following virus entry. The activation of viral protease (PR) to mediate virus particle processing helps viruses acquire infectivity following cell release. RT and PR both appear to be major targets for inhibiting HIV-1 replication. We found a strong correlation between impaired p66/51RT stability and deficient PR-mediated Gag cleavage, suggesting that RT/RT interaction is critical for triggering PR activation via the promotion of adequate Gag-Pol dimerization. Accordingly, RT/RT interaction is a potentially advantageous method for anti-HIV/AIDS therapy if it is found to simultaneously block PR and RT enzymatic activity.

Rust resistance SH3 loci in Coffea spp.

Resistance to the leaf rust delivered by SH3 factor(s) from Coffea liberica is well-grounded as specially durable. We analyzed C. liberica SH3 genes, here described for the first time, and SH3 loci in other Coffea species, taking C. arabica cv. IAPAR59 as reference. All species display multiple SH3-RxCC-NBS-LRR variants. SH3-Rx proteins, charged with RanGAP2 co-factors and fungi effectors in the cytoplasm, potentially, target DNA directly to trigger defense. C. liberica SH3-RxCC-NBS-LRR set is large, comprising more orthologs to A. thaliana CAR1 and 'canonical' leucine repeats among diploids analyzed. Interestingly, genes sharing the loci with SH3-RxCC-NBS-LRRs are preserved and defense related.

Leucine Repeat Rich Kinase 1 Controls Osteoclast Activity by Managing Lysosomal Trafficking and Secretion.

We previously demonstrated that mice with targeted deletion of the leucine repeat rich kinase 1 (Lrrk1) gene were osteopetrotic due to the failure of osteoclasts to resorb bone. To determine how LRRK1 regulates osteoclast activity, we examined the intracellular and extracellular acidification with an acidotropic probe, acridine orange, in live osteoclasts on bone slices. We examined lysosome distribution in osteoclasts by localization of LAMP-2, cathepsin K, and v-ATPase by immunofluorescent staining with specific antibodies. We found that both vertical and horizontal cross-sectional images of the wild-type (WT) osteoclasts showed orange-staining of the intracellular acidic vacuoles/lysosomes dispersed to the ruffled border. By contrast, the LRRK1 deficient osteoclasts exhibited fluorescent orange staining in the cytoplasm away from the extracellular lacunae because of an altered distribution of the acidic vacuoles/lysosomes. In addition, WT osteoclasts displayed a peripheral distribution of LAMP-2 positive lysosomes with a typical actin ring. The clustered F-actin constitutes a peripheral sealing zone and a ruffled border which was stretched out into a resorption pit. The LAMP-2 positive lysosomes were also distributed to the sealing zone, and the cell was associated with a resorption pit. By contrast, LRRK1-deficient osteoclasts showed diffused F-actin throughout the cytoplasm. The sealing zone was weak and not associated with a resorption pit. LAMP-2 positive lysosomes were also diffuse in the cytoplasm and were not distributed to the ruffled border. Although the LRRK1-deficient osteoclast expressed normal levels of cathepsin K and v-ATPase, the lysosomal-associated cathepsin K and v-ATPase were not accumulated at the ruffled border in Lrrk1 KO osteoclasts. Our data indicate that LRRK1 controls osteoclast activity by regulating lysosomal distribution, acid secretion, and protease exocytosis.

Identification and Functional Analysis of bZIP Genes in Cotton Response to Drought Stress

The basic leucine zipper (bZIP) transcription factors, which harbor a conserved bZIP domain composed of two regions, a DNA-binding basic region and a Leu Zipper region, operate as important switches of transcription networks in eukaryotes. However, this gene family has not been systematically characterized in cotton (Gossypium hirsutum). Here, we identified 197 bZIP family members in cotton. The chromosome distribution pattern indicates that the GhbZIP genes have undergone 53 genome-wide segmental and 7 tandem duplication events which contribute to the expansion of the cotton bZIP family. Phylogenetic analysis showed that cotton GhbZIP proteins cluster into 13 subfamilies, and homologous protein pairs showed similar characteristics. Inspection of the DNA-binding basic region and leucine repeat heptads within the bZIP domains indicated different DNA-binding site specificities as well as dimerization properties among different groups. Comprehensive expression analysis indicated the most highly and differentially expressed genes in root and leaf that might play significant roles in cotton response to drought stress. GhABF3D was identified as a highly and differentially expressed bZIP family gene in cotton leaf and root under drought stress treatments that likely controls drought stress responses in cotton. These data provide useful information for further functional analysis of the GhbZIP gene family and its potential application in crop improvement.

Platelet caspase‐1 and Bruton tyrosine kinase activation in patients with COVID‐19 is associated with disease severity and reversed in vitro by ibrutinib

BackgroundSeverity of coronavirus disease 2019 (COVID‐19) is often associated with thrombotic complications and cytokine storm leading to intensive are unit (ICU) admission. Platelets are known to be responsible for abnormal hemostasis parameters (thrombocytopenia, raised D‐dimers, and prolonged prothrombin time) in other viral infections through the activation of the nucleotide‐binding domain leucine repeat rich containing protein 3 inflammasome induced by signaling pathways driven by Bruton tyrosine kinase (BTK) and leading to caspase‐1 activation. ObjectivesWe hypothesized that caspase‐1 activation and the phosphorylation of BTK could be associated with the severity of the disease and that ibrutinib, a BTK inhibitor, could inhibit platelet activation. Methods and ResultsWe studied caspase‐1 activation by flow cytometry and the phosphorylation of BTK by Western blot in a cohort of 51 Afro‐Carribean patients with COVID‐19 disease (19 not treated in ICU and 32 treated in ICU). Patients with a platelet count of 286.7 × 109/L (69–642 × 109/L) were treated by steroids and heparin preventive anticoagulation. Caspase‐1 and BTK activation were associated with the severity of the disease and with the procoagulant state of the patients. Furthermore, we showed in vitro that the plasma of ICU patients with COVID‐19 was able to increase CD62P expression and caspase‐1 activity of healthy platelets and that ibrutinib could prevent it. ConclusionsOur results show that caspase‐1 and BTK activation are related to disease severity and suggest the therapeutic hope raised by ibrutinib in the treatment of COVID‐19 by reducing the procoagulant state of the patients.

Galangin ameliorates osteoarthritis progression by attenuating extracellular matrix degradation in chondrocytes via the activation of PRELP expression

Osteoarthritis (OA) is primarily characterized by progressive degeneration and destruction of articular cartilage. Currently, there is no effective method to treat OA. The metabolic disturbance of cartilage extracellular matrix (ECM) and oxidative stress are critical to promote OA progression. Galangin (Gal) is a small molecule compound that pertains to flavonoids. To determine the protective effect and mechanism of Gal against OA progression, various experiments were performed in vitro and in vivo. In vitro, Gal promoted ECM production and attenuated ECM degradation in human OA chondrocytes. The expression of ECM components from human OA cartilage explants was also stimulated by Gal treatment. As demonstrated from the in vivo study, the intra-articular injection of Gal delayed OA progression in rat models. Moreover, RNA sequencing analysis showed that proline/arginine-rich end leucine repeat protein (PRELP) was a molecular target of Gal activity. Gal inhibited oxidative stress and attenuated ECM degradation by activating PRELP expression. The study demonstrated that Gal could attenuate ECM degradation and ameliorate OA progression, and PRELP may be a potential candidate drug of Gal for treating OA.

MRNA expression profiling of the cancellous bone in patients with idiopathic osteonecrosis of the femoral head by whole-transcriptome sequencing.

Idiopathic osteonecrosis of the femoral head (INFH) seriously affects patients’ activities and is a heavy burden to society and patients’ families. Therefore, the early diagnosis and treatment of INFH is essential in reducing pain and burden. In the present study, the cancellous bone under the cartilage of the femoral head was isolated from patients with INFH and femoral neck fracture (FNF). Histological examination revealed that the bone trabecular and the medullary cavity in the INFH group compared with those in the FNF group. Whole-transcriptome sequencing (WTS), a recently applied technology, plays a significant role in the screening of risk factors associated with the onset of femoral head necrosis. Herein, WTS was used to obtain the mRNA expression profile in the cancellous bone of the femoral head isolated from 5 patients with INFH and 5 patients with FNF. Compared with the FNF group, a total of 155 differentially expressed genes were identified in the INFH group. Among these genes, 96 and 59 were upregulated and downregulated, respectively. Reverse transcription-quantitative PCR and western blot analyses revealed that leucine-rich repeat-containing 17 (LRRC17) displayed the most significantly decreased mRNA and protein expression levels between the INFH and FNF groups. The expression profile of the differentially expressed genes and LRRC17 protein in the INFH and FNF groups was consistent with that obtained by WTS. LRRC17, a leucine repeat sequence, plays a significant role in regulating bone metabolism, thus indicating that LRRC17 downregulation could affect bone metabolism and could be considered a key factor in the pathogenesis of INFH.

Abstract GS106: Asporin, An Extracellular Matrix Protein, Is A Beneficial Regulator Of Cardiac Remodeling

Heart failure is accompanied by adverse cardiac remodeling involving extracellular matrix (ECM). Cardiac ECM acts as a major reservoir for many proteins including growth factors, cytokines, collagens, and proteoglycans. Activated fibroblasts during cardiac injury can alter the composition and activity of these ECM proteins. Through unbiased analysis of a microarray dataset of human heart tissue comparing normal hearts (n=135) to hearts with ischemic cardiomyopathy (n=94), we identified Asporin (ASPN) as the top differentially regulated gene (DEG) in ischemic cardiomyopathy; its gene-ontology terms relate closely to fibrosis and cell death. ASPN is a Class I small leucine repeat protein member implicated in cancer, osteoarthritis, and periodontal ligament mineralization. However, its role in cardiac remodeling is still unknown. Here, we initially confirmed our big dataset analysis through cells, mice, and clinical atrial biopsy samples to demonstrate increased ASPN expression after pressure overload or cardiac ischemia/reperfusion injury. We tested the hypothesis that ASPN, being a TGFβ1 inhibitor, can attenuate fibrosis in mouse models of cardiac injury. We found that ASPN is released by cardiac fibroblasts and attenuates TGFβ signaling. Moreover, ASPN -/- mice displayed increased fibrosis and decreased cardiac function after pressure overload by transverse aortic constriction (TAC) in mice. In addition, ASPN protected cardiomyocytes from hypoxia/reoxygenation-induced cell death and regulated autophagy and mitochondrial bioenergetics in cardiomyocytes. Increased infarct size after ischemia/reperfusion injury in ASPN -/- mice confirmed ASPN’s contribution to cardiomyocyte viability. Echocardiography revealed a greater reduction in left ventricular systolic function post-I/R in the ASPN -/- animals compared to wild type. Furthermore, we developed an ASPN-mimic peptide using molecular modeling and docking which when administered to mice prevented TAC-induced fibrosis and preserved heart function. The peptide also reduced infarct size after I/R in mice, demonstrating the translational potential of ASPN-based therapy. Thus, we establish the role of ASPN as a critical ECM molecule that regulates cardiac remodeling to preserve heart function.

The Role of SliTrk5 in Central Nervous System.

SLIT and NTRK-like protein-5 (SliTrk5) is one of the six members of SliTrk protein family, which is widely expressed in the central nervous system (CNS), regulating and participating in many essential steps of central nervous system development, including axon and dendritic growth, neuron differentiation, and synaptogenesis. SliTrk5, as a neuron transmembrane protein, contains two important conservative domains consisting of leucine repeats (LRRs) located at the amino terminal in the extracellular region and tyrosine residues (Tyr) located at the carboxyl terminal in the intracellular domains. These special structures make SliTrk5 play an important role in the pathological process of the CNS. A large number of studies have shown that SliTrk5 may be involved in the pathogenesis of CNS diseases, such as obsessive-compulsive-disorder (OCD), attention deficit/hyperactivity disorder (ADHD), glioma, autism spectrum disorders (ASDs), and Parkinson's disease (PD). Targeting SliTrk5 is expected to become a new target for the treatment of CNS diseases, promoting the functional recovery of CNS. The purpose of this article is to review the current research progression of the role of SliTrk5 in CNS and its potential mechanisms in CNS diseases.

Asporin, an extracellular matrix protein, is a beneficial regulator of cardiac remodeling

Heart failure is accompanied by adverse cardiac remodeling involving extracellular matrix (ECM). Cardiac ECM acts as a major reservoir for many proteins including growth factors, cytokines, collagens, and proteoglycans. Activated fibroblasts during cardiac injury can alter the composition and activity of these ECM proteins. Through unbiased analysis of a microarray dataset of human heart tissue comparing normal hearts (n = 135) to hearts with ischemic cardiomyopathy (n = 94), we identified Asporin (ASPN) as the top differentially regulated gene (DEG) in ischemic cardiomyopathy; its gene-ontology terms relate closely to fibrosis and cell death. ASPN is a Class I small leucine repeat protein member implicated in cancer, osteoarthritis, and periodontal ligament mineralization. However, its role in cardiac remodeling is still unknown. Here, we initially confirmed our big dataset analysis through cells, mice, and clinical atrial biopsy samples to demonstrate increased Aspn expression after pressure overload or cardiac ischemia/reperfusion injury. We tested the hypothesis that Aspn, being a TGFβ1 inhibitor, can attenuate fibrosis in mouse models of cardiac injury. We found that Aspn is released by cardiac fibroblasts and attenuates TGFβ signaling. Moreover, Aspn−/− mice displayed increased fibrosis and decreased cardiac function after pressure overload by transverse aortic constriction (TAC) in mice. In addition, Aspn protected cardiomyocytes from hypoxia/reoxygenation-induced cell death and regulated mitochondrial bioenergetics in cardiomyocytes. Increased infarct size after ischemia/reperfusion injury in Aspn−/− mice confirmed Aspn's contribution to cardiomyocyte viability. Echocardiography revealed greater reduction in left ventricular systolic function post-I/R in the Aspn−/− animals compared to wild type. Furthermore, we developed an ASPN-mimic peptide using molecular modeling and docking which when administered to mice prevented TAC-induced fibrosis and preserved heart function. The peptide also reduced infarct size after I/R in mice, demonstrating the translational potential of ASPN-based therapy. Thus, we establish the role of ASPN as a critical ECM molecule that regulates cardiac remodeling to preserve heart function.

IDF21-0406 Genetic variants in the Carnosine-Carnosinase system and their impact on diabetic nephropathy

Background: The role of carnosine-carnosinase system in diabetic nephropathy has been established through various studies in animal models. It has been proven that low carnosinase secretion promotes high circulating carnosine levels which acts as a protective factor against adverse effects of hyperglycemia on renal cells. While genetic variants in the carnosinase gene (CNDP1) could influence carnosinase concentration, variants in the carnosine synthase gene (CARNS1) which synthesizes carnosine and variants in the SLC15A4 and SLC15A2 genes which are involved in the renal transport of carnosine could influence carnosine concentration thereby causing nephropathy. Aim: To study the association of genetic variants in the carnosine-carnosinase system (CARNS1, CNDP1, SLC15A4 and SLC15A2) with nephropathy and their influence on carnosinase levels in south Indian population. Method: Study Participants: 580 type 2 diabetes individuals without nephropathy (DM) and 597 type 2 diabetes individuals with nephropathy (DN) from Dr. Mohan’s Diabetes Specialities Centre, Chennai, India. Methodology: Genomic DNA was extracted from blood samples using phenol chloroform method. A total of 27 SNPs from the four genes were genotyped using MassARRAY. The levels of carnosinase in serum was measured in 116 DM and 93 DN participants using commercially available ELISA kit. Results: The D18S880 repeat polymorphism (5-8 repeats of Leucine) in CNDP1 gene and rs1626067 SNP of CARNS1 gene showed significant association with DN. The odds ratio for DN after adjusting for potential confounders such as age, sex, BMI, HbA1c, duration of diabetes and systolic blood pressure for the 6L/XL genotype of D18S880 and the GA genotype of rs1626067 as compared to their respective homozygous normal genotypes was 0.67 (95%CI: 0.48-0.94, p=0.022) and 0.68 (95% CI:0.49-0.93, p=0.016) respectively. The levels of carnosinase (mean±SE in picogram/mL) was significantly higher in DN (3.07±0.19) compared to DM group (2.48±0.13, p=0.038). Discussion: This study gains significance as the role of genetic variants in the carnosine-carnosinase system in DN remains largely unexplored. Most of the studies so far have focussed only on the CNDP1 gene. The association of D18S880 Leucine repeat with DN is significant as it is present in the signal peptide region of CNDP1 gene and may play a role in the secretion of carnosinase. The association of rs1626067 SNP in CARNS1 with DN has not been reported so far. This SNP is positioned in the 3́UTR region of CARNS1 and hence could alter the binding of transcription factors and have a regulatory effect. The significant difference in serum carnosinase levels between DM and DN groups was an interesting finding. When the groups were further stratified based on the genotypes, the sample size was less than 50 in each group and was not sufficiently powered to study the correlation of enzyme levels and genotypes. Measuring the levels and activity of carnosinase in larger number of samples will help identify whether the genetic variations influence the enzyme levels. If found, targeted dietary intervention studies giving carnosine supplements to those carrying the susceptible alleles can be undertaken to alleviate the burden of nephropathy.

InlF Enhances Listeria monocytogenes Early-Stage Infection by Inhibiting the Inflammatory Response.

The internalin family proteins, which carry the leucine repeat region structural motif, play diverse roles in Listeria monocytogenes (Lm) infection and pathogenesis. Although Internalin F, encoded by inlF, was identified more than 20 years ago, its role in the Lm anti-inflammatory response remains unknown. Lm serotype 4b isolates are associated with the majority of listeriosis outbreaks, but the function of InlF in these strains is not fully understood. In this study, we aimed to elucidate the role of inlF in modulating the inflammatory response and pathogenesis of the 4b strain Lm NTSN. Strikingly, although inlF was highly expressed at the transcriptional level during infection of five non-phagocytic cell types, it was not involved in adherence or invasion. Conversely, inlF did contributed to Lm adhesion and invasion of macrophages, and dramatically suppressed the expression of pro-inflammatory cytokines interleukin (IL)-1β and tumor necrosis factor (TNF-α). Consistent with the in vitro results, during Lm infection mice, inlF significantly inhibited the expression of IL-1β and IL-6 in the spleen, as well as IL-1β, IL-6, and TNF-α in the liver. More importantly, inlF contributed to Lm colonization in the spleen, liver, and ileum during the early stage of mouse infection via intragastric administration, inducing severe inflammatory injury and histopathologic changes in the late stage. To our knowledge, this is the first report to demonstrate that inlF mediates the inhibition of the pro-inflammatory response and contributes to the colonization and survival of Lm during the early stage of infection in mice. Our research partly explains the high pathogenicity of serovar 4b strains and will lead to new insights into the pathogenesis and immune evasion of Lm.

Decorin: a multifunctional proteoglycan involved in oocyte maturation and trophoblast migration.

Decorin (DCN) is a proteoglycan belonging to the small leucine-rich proteoglycan family. It is composed of a protein core containing leucine repeats with a glycosaminoglycan chain consisting of either chondroitin sulfate or dermatan sulfate. DCN is a structural component of connective tissues that can bind to type I collagen. It plays a role in the assembly of the extracellular matrix (ECM), and it is related to fibrillogenesis. It can interact with fibronectin, thrombospondin, complement component C1, transforming growth factor (TGF), and epidermal growth factor receptor. Normal DCN expression regulates a wide range of cellular processes, including proliferation, migration, apoptosis, and autophagy, through interactions with various molecules. However, its aberrant expression is associated with oocyte maturation, oocyte quality, and poor extravillous trophoblast invasion of the uterus, which underlies the occurrence of preeclampsia and intrauterine growth restriction. Spatiotemporal hormonal control of successful pregnancy should regulate the concentration and activity of specific proteins such as proteoglycan participating in the ECM remodeling of trophoblastic and uterine cells in fetal membranes and uterus. At the human feto-maternal interface, TGF-β and DCN play crucial roles in the regulation of trophoblast invasion of the uterus. This review summarizes the role of the proteoglycan DCN as an important and multifunctional molecule in the physiological regulation of oocyte maturation and trophoblast migration. This review also shows that recombinant DCN proteins might be useful for substantiating diverse functions in both animal and in vitro models of oogenesis and implantation.

Prec-O2-02 - Anti-tumor effect of anti-apoptosis clone 11 protein-derived peptides on Sézary syndrome malignant CD4+ T lymphocytes

Sézary syndrome (SS) is a rare, aggressive leukemic form of cutaneous T-cell lymphoma characterized by generalized erythroderma, lymphadenopathy and circulating malignant CD4+ T cells (Sézary cells). Sézary syndrome evolves very quickly, patients are severely immunocompromised and their quality of life is drastically impaired. SS prognosis remains dismal despite recent therapeutic advances. AAC-11 (Anti-Apoptosis Clone 11, also known as Api5) is a survival scaffold protein that is widely expressed in cancer cells. Recent data indicate that AAC-11 might to be one of the central molecules involved in cancer cell progression and survival. Therefore, its inactivation might constitute an attractive approach for developing novel cancer therapeutics. AAC-11 contains a heptad leucine repeat domain that constitutes a protein-protein interaction motif, allowing its interaction with several apoptosis regulatory proteins. Loss-of-function mutations of the heptad leucine repeat motif are responsible for a defect in the interaction with its binding partners and associated with an abolition of the survival properties of AAC-11. We have recently described cell penetrating peptides based on the fusion of penetratin and a portion of the heptad leucine repeat region of AAC-11 that can induce cancer cells death. This effect is not observed in normal cells, suggesting high therapeutic indices. Here we evaluated the anti-tumor effect of a novel AAC-11-derived peptide, termed RT39, in the context of Sézary syndrome. Our results demonstrate that RT39 exerts an efficient and specific cytotoxic activity towards Sézary cells, while sparring the other immune cell populations, both <i>ex vivo</i> on primary patient cells and <i>in vivo</i> in preclinical Sézary syndrome murine models. Mechanistic studies revealed that RT39 induces membranolysis of Sézary cells by means of binding to p21-activated kinase 1 (PAK1) in the context of Sézary cells plasma membrane, where PAK1 is overexpressed. Preliminary pharmacokinetic studies in mice indicated that, after intravenous, subcutaneous or intraperitoneal administration, the half-life of the peptide is of the order of 30 minutes, but the elimination phase is very prolonged with high AUCs, indicative of durable exposure. Along with excellent tolerability in mice, our preclinical results support the development of RT39 as a new therapeutic strategy in Sézary syndrome.

Genome-wide association study for adult plant resistance to yellow rust in spring bread wheat (Triticum aestivum L.)

Yellow rust, caused by Puccinia striiformis f. sp. tritici, is a common and serious fungal disease of wheat (Triticum aestivum L.) all over the world and particularly in the Central and West Asia and North Africa region. To identify effective yellow rust resistance loci, genome-wide association study (GWAS) was performed using 196 bread wheat genotypes based on 10,477 single nucleotide polymorphisms markers. Adult plants were evaluated under field conditions for resistance to yellow rust for 2 years (2014–2015) at ICARDA station, Marchouch, Morocco. Out of the 196 genotypes, 85 genotypes (43.37%) were resistant, 22 genotypes (11.22%) were moderately resistant, 13 genotypes (6.63%) were moderately susceptible, 48 genotypes (24.49%) were moderately susceptible to susceptible and 28 genotypes (14.29%) were susceptible to Puccinia striiformis f. sp. tritici. GWAS using mixed linear model identified 23 markers on chromosomes 2A, 2B, 2D and 7B significantly associated with adult plant resistance at false discovery rate (FDR-adjusted P ≤ 0.05). Of which, three markers were within 10 wheat functional genes involved in several plant disease resistance and defense mechanism. Five of the reported functional genes are annotated as disease resistance proteins with nucleotide-binding site leucine repeat domains. BLAST analysis confirmed that YrR61 and Yr17 were mostly the candidate genes linked to the marker Tdurum_contig29983_490 on chromosome 2A. Moreover, markers identified on chromosome 7B and Kukri_c12648_434 on 2D were not mapped within any of previously reported gene/QTL region hence, representing novel resistance loci for Pst and needs to be confirmed using an allelism test.