Publications by authors named "Cesar Santiago"

Article Synopsis
  • Abscisic acid (ABA) is crucial for plant development and helps plants respond to environmental stress by regulating key signaling pathways.
  • The ubiquitin-proteasome system, specifically CULLIN4-RING (CRL4) E3 ubiquitin ligases, negatively regulates ABA receptor PYL8 through a complex known as CDD, leading to PYL8 degradation.
  • ABA enhances the stability of PYL8 by disrupting CRL4-CDDD complexes and altering their interaction with the COP9 signalosome, demonstrating how plants use hormones to protect their receptors from degradation.
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  • - CXCR4 is a chemokine receptor that plays key roles in immune cell movement, organ development, and various diseases, including cancer and HIV-1 infection, with only one blocker, plerixafor, currently used clinically.
  • - Recent research shows that when activated by CXCL12, CXCR4 changes its structure, reducing membrane-bound units and forming larger immobile clusters necessary for cells to respond to chemical signals.
  • - Using molecular modeling, scientists discovered a compound, AGR1.137, that disrupts these CXCR4 clusters without interfering with CXCL12 binding, effectively blocking cellular response to chemical gradients in laboratory settings.
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The increased prevalence of autism spectrum disorder (ASD) has placed a significant emotional and psychological burden on mothers. We explored the association between the severity of ASD symptoms in children and the mental health of their mothers during the COVID-19 pandemic. Our study included 1,924 mothers of children with ASD, enrolled in a web-based cross-sectional survey over 85 consecutive days to gather clinical and sociodemographic data.

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  • WHIM syndrome is caused by heterozygous mutations in the CXCR4 gene, leading to severe immunodeficiency due to altered receptor functions.* -
  • These mutations affect phosphorylation sites in the CXCR4 receptor, resulting in prolonged activation and hyperactive signaling on the cell surface.* -
  • Recent research suggests that mutant WHIM receptors behave differently than normal CXCR4, affecting their roles in both normal physiology and disease processes.*
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Here we report the characterization of 17T2, a SARS-CoV-2 pan-neutralizing human monoclonal antibody isolated from a COVID-19 convalescent individual infected during the first pandemic wave. 17T2 is a class 1 VH1-58/κ3-20 antibody, derived from a receptor binding domain (RBD)-specific IgA memory B cell, with a broad neutralizing activity against former and new SARS-CoV-2 variants, including XBB.1.

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J-domain proteins tune the specificity of Hsp70s, engaging them in precise functions. Despite their essential role, the structure and function of many J-domain proteins remain largely unknown. We explore human DNAJA2, finding that it reversibly forms highly-ordered, tubular structures that can be dissociated by Hsc70, the constitutively expressed Hsp70 isoform.

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p38γ and p38δ (p38γ/p38δ) regulate inflammation, in part by controlling tumor progression locus 2 (TPL2) expression in myeloid cells. Here, we demonstrate that TPL2 protein levels are dramatically reduced in p38γ/p38δ-deficient (p38γ/δ) cells and tissues without affecting messenger ribonucleic acid (mRNA) expression. We show that p38γ/p38δ posttranscriptionally regulates the TPL2 amount at two different levels.

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Article Synopsis
  • The organization of chemokine receptors at the cell membrane is heavily influenced by the actin cytoskeleton, affecting how cells respond to signals.
  • The truncated CXCR4 receptor mutant (CXCR4R334X), connected to WHIM syndrome, shows altered behavior, failing to cluster properly and affecting receptor mobility after stimulation with CXCL12.
  • The study reveals that CXCR4R334X causes improper actin remodeling due to inadequate activation of β-arrestin1, which can lead to severe immune system issues seen in patients with WHIM syndrome.
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Tyrosine hydroxylase (TH) catalyzes the rate-limiting step in the biosynthesis of dopamine (DA) and other catecholamines, and its dysfunction leads to DA deficiency and parkinsonisms. Inhibition by catecholamines and reactivation by S40 phosphorylation are key regulatory mechanisms of TH activity and conformational stability. We used Cryo-EM to determine the structures of full-length human TH without and with DA, and the structure of S40 phosphorylated TH, complemented with biophysical and biochemical characterizations and molecular dynamics simulations.

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Dendritic cells (DCs) are the most potent antigen-presenting cells, and their function is essential to configure adaptative immunity and avoid excessive inflammation. DCs are predicted to play a crucial role in the clinical evolution of the infection by the severe acute respiratory syndrome (SARS) coronavirus (CoV)-2. DCs interaction with the SARS-CoV-2 Spike protein, which mediates cell receptor binding and subsequent fusion of the viral particle with host cell, is a key step to induce effective immunity against this virus and in the S protein-based vaccination protocols.

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  • The TLR family consists of receptors that detect pathogen-associated molecular patterns, which trigger inflammation and adaptive immunity; TLR2 is significant for identifying both bacteria and some viruses.
  • This study focuses on TLR2's involvement in the immune response to peste des petits ruminants virus (PPRV), finding that PPRV induces IL-8 production in cells with TLR2.
  • The hemagglutinin protein from PPRV activates TLR2, leading to pro-inflammatory responses and IL-12 secretion, crucial for controlling PPR in affected animals.
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Background And Objectives: Published comparisons of minimally invasive approaches to colon surgery are limited. The objective of the current study is to compare the effectiveness of robotic-assisted and laparoscopic sigmoid resection.

Methods: A multicenter retrospective comparative analysis of perioperative outcomes from consecutive robotic-assisted and laparoscopic sigmoid resections performed between 2010 and 2015 by six general and colorectal surgeons, who are experienced in both robotic-assisted and laparoscopic surgical techniques and who had >50 annual case volumes for each approach.

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There is an urgent need for the development of potent vaccination regimens that are able to induce specific T and B cell responses against human immunodeficiency virus type 1 (HIV-1). Here, we describe the generation and characterization of a fusion antigen comprised of the HIV-1 envelope GP120 glycoprotein from clade C (GP120C) fused at its C-terminus, with the modified vaccinia virus (VACV) 14K protein ( gene) (termed GP120C14K). The design is directed toward improving the immunogenicity of the GP120C protein through its oligomerization facilitated by the fused VACV 14K protein that results in hexamer-like structures.

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Aggregation and accumulation of amyloid beta (Aβ) are believed to play a key role in the pathogenesis of Alzheimer's disease (AD). We previously reported that Thioredoxin-80 (Trx80), a truncated form of Thioredoxin-1, prevents the toxic effects of Aβ and inhibits its aggregation in vitro. Trx80 levels were found to be dramatically reduced both in the human brain and cerebrospinal fluid of AD patients.

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Article Synopsis
  • Chemokine receptors, especially CXCR4, are crucial for regulating cell movement and positioning in various physiological processes and diseases, including embryogenesis and immune responses.
  • CXCR4 is known for its unique ligand, SDF1 (CXCL12), and its interaction with ACKR3, making it a key player in tumor progression and autoimmune diseases.
  • The CXCL12/CXCR4/ACKR3 signaling pathway presents a promising therapeutic target for inflammatory conditions, with AMD3100 being the only notable antagonist showing clinical significance.
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The mechanistic target of rapamycin (mTOR) kinase forms two multi-protein signaling complexes, mTORC1 and mTORC2, which are master regulators of cell growth, metabolism, survival and autophagy. Two of the subunits of these complexes are mLST8 and Raptor, β-propeller proteins that stabilize the mTOR kinase and recruit substrates, respectively. Here we report that the eukaryotic chaperonin CCT plays a key role in mTORC assembly and signaling by folding both mLST8 and Raptor.

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Background: Decompressive craniectomy may be used as a primary or secondary treatment for intracranial hypertension and is clearly associated with reduced mortality. The removed bone flap is usually preserved in the abdominal subcutaneous tissue or in the bone bank. The aim of this study was to describe an option for preserving the bone flap after decompressive craniectomy using bone flap preservation in the skull subcutaneous tissue in subgaleal space over the pericranium contralateral to the craniectomy site.

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Article Synopsis
  • Current studies in cell motility aim to understand how the organization of chemokine receptors at the cell membrane affects cell behavior, particularly focusing on the chemokine receptor CXCR4 in T cells.
  • Using advanced imaging techniques, researchers found that CXCR4 forms nanoclusters in resting T cells, which are influenced by the actin cytoskeleton, the CD4 co-receptor, and its ligand CXCL12.
  • The study identified key structural residues in CXCR4 necessary for these nanoclusters, demonstrating that without proper clustering, even receptor dimerization can't effectively support signaling and cell functions in response to CXCL12.
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Inflammation and tissue regeneration follow tissue damage, but little is known about how these processes are coordinated. High Mobility Group Box 1 (HMGB1) is a nuclear protein that, when released on injury, triggers inflammation. We previously showed that HMGB1 with reduced cysteines is a chemoattractant, whereas a disulfide bond makes it a proinflammatory cytokine.

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Studies in recent years have established that the principal effects in cardiac cell therapy are associated with paracrine/autocrine factors. We combined several complementary techniques to define human cardiac progenitor cell (CPC) secretome constituted by 914 proteins/genes; 51% of these are associated with the exosomal compartment. To define the set of proteins specifically or highly differentially secreted by CPC, we compared human mesenchymal stem cells and dermal fibroblasts; the study defined a group of growth factors, cytokines and chemokines expressed at high to medium levels by CPC.

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Cell surface aminopeptidase N (APN) is a membrane-bound ectoenzyme that hydrolyzes proteins and peptides and regulates numerous cell functions. APN participates in tumor cell expansion and motility, and is a target for cancer therapies. Small drugs that bind to the APN active site inhibit catalysis and suppress tumor growth.

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The chemokine receptor, CXC chemokine receptor 4 (CXCR4), is selective for CXC chemokine ligand 12 (CXCL12), is broadly expressed in blood and tissue cells, and is essential during embryogenesis and hematopoiesis. CXCL14 is a homeostatic chemokine with unknown receptor selectivity and preferential expression in peripheral tissues. Here, we demonstrate that CXCL14 synergized with CXCL12 in the induction of chemokine responses in primary human lymphoid cells and cell lines that express CXCR4.

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As aberrant protein phosphorylation is a hallmark of tumor cells, the display of tumor-specific phosphopeptides by Human Leukocyte Antigen (HLA) class I molecules can be exploited in the treatment of cancer by T-cell-based immunotherapy. Yet, the characterization and prediction of HLA-I phospholigands is challenging as the molecular determinants of the presentation of such post-translationally modified peptides are not fully understood. Here, we employed a peptidomic workflow to identify 256 unique phosphorylated ligands associated with HLA-B*40, -B*27, -B*39, or -B*07.

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