Biology subjects

Dias, W. B.

Publications and source records attributed to Dias, W. B..

5 recordsLinked to original sources

bioRxiv2026

HUMAN-LIKE SIALOME REMODELING LINKS HYPERGLYCEMIA TO COLORECTAL CANCER PROGRESSION

The evolutionary loss of cytidine monophosphate-N-acetylneuraminic acid hydroxylase (CMAH) abolished endogenous N-glycolylneuraminic acid (Neu5Gc) synthesis in humans, reshaping the sialic acid at the cell surface glycans and influencing immune and metabolic processes. However, whether a human-like sialome modulates the impact of metabolic stress on colorectal cancer (CRC) progression remains unclear. Here, we investigated the diabetes-sialome-tumor axis using a spontaneous CRC model combining conditional Apc mutation with Cmah deficiency, thereby recapitulating the human sialic acid repertoire. Under euglycemic conditions, CPC-Apc Cmah-/- mice exhibited reduced polyp numbers and tumor burden compared with WT mice, accompanied by remodeling of the tumor immune microenvironment, including increased tumor-infiltrating leukocytes, enrichment of B cells, and reduced PD-1 expression in B cells and cytotoxic CD8+ T cells. Induction of chronic hyperglycemia with low-dose streptozotocin revealed a striking genotype-specific effect. Despite comparable hyperglycemia between genotypes, tumor progression was dramatically exacerbated exclusively in Cmah-/- mice, with increased tumor burden, accelerated lesion development, and progression toward high-grade dysplasia. Histopathological analyses further revealed increased mesenchymal expansion and close resemblance to colorectal tumors from diabetic patients. Together, these findings demonstrate that a human-like sialome increases susceptibility to metabolic stress and identify CPC-Apc Cmah-/- mice as a translationally relevant model for investigating diabetes-associated colorectal carcinogenesis.

cancer biology↗

bioRxiv2023

Sex-specific effect of antenatal Zika virus infection on murine fetal growth, placental nutrient transporters, and nutrient sensor signaling pathways

Maternal Zika virus (ZIKV) infection during pregnancy can associate with severe intrauterine growth restriction (IUGR), placental damage, and metabolism disturbance, as well as newborn neurological abnormalities. Here, we investigated whether maternal ZIKV infection affects placental nutrient transporters and nutrient-sensitive pathways. Immunocompetent (C57BL/6) mice were injected with Low (103 PFU-ZIKVPE243) and High (5x107 PFU-ZIKVPE243) ZIKV titers at gestational day (GD) 12.5, for tissue collection at GD18.5 (term). Feto-placental growth of male fetuses was dramatically affected by ZIKV, whereas no differences were observed in female fetuses. ZIKV promoted increased expression of glucose transporter type 1 (Slc2a1/Glut1) and decreased levels of glucose-6-phosphate in female placentas, with no differences in amino-acid transport potential. In contrast, glucose transport in male placentas was not affected by ZIKV, whilst a decreased placental protein expression of sodium-coupled neutral amino acid 2 (Snat2) was detected in the male low-dose ZIKV-infected group. There were also sex-dependent differences in the hexosamine biosynthesis pathway (HBP) and O-GlcNAcylation in ZIKV infected pregnancies, showing that ZIKV can cause disturbance in the nutrient handling in the placental tissue. Our findings thus identify relevant molecular alterations in the placenta caused by maternal ZIKV infection related to nutrient transport and availability. Notably, our results suggest that female and male placentas adopt different strategies to cope with the altered metabolic state caused by ZIKV. This may have relevance for understanding the effects of congenital Zika syndrome and could potentially assist future therapeutic strategies. Author SummaryThe Zika virus (ZIKV) has emerged as a major global health concern in the past decade. ZIKV infection during pregnancy can cause infants to be born with microcephaly and fetal growth restriction, among other pregnancy complications. Currently, the number of cases of ZIKV disease declined onwards globally. However, transmission persists at low levels in several countries in the Americas and other endemic regions, with neither a licensed vaccine nor an antiviral drug available for prevention and treatment. Here, we use a mice model of maternal ZIKV infection to analyze placental nutrient transporters and nutrient-sensitive pathways as a potential link to the complications related to congenital ZIKV infection. We found that feto-placental growth of male fetuses was dramatically affected by ZIKV, whereas no differences were observed in female fetuses. We also found that placental nutrient transporters and nutrient-sensitive pathways were altered in response to ZIKV infection, depending on the fetal sex. Our study presents relevant molecular alterations caused by maternal ZIKV infection and suggests that female and male placentas adopt different strategies in response to the altered environment caused by ZIKV. Our observations may have relevance for understanding the effects of ZIKV infection and could potentially assist future therapeutic strategies.

physiology↗

bioRxiv2022

Repurposing the CRISPR-Cas9 System for Targeted Chromatin O-linked β-N- acetylglucosamine Editing

Eukaryotic gene transcription is controlled by many proteins, including the basal transcription machinery, epigenetic chromatin remodeling complexes, and transcription cofactors. Chromatin and genome-mapping consortia identified O-linked {beta}-N-acetylglucosamine (O-GlcNAc) as an abundant chromatin post-translational modification involved in numerous transcriptional processes, including RNA polymerase function, epigenetic dynamics, and transcription factor activity. Thus, O-GlcNAc regulation of cis-regulatory elements is essential for proper gene expression. O-GlcNAc is a single N-acetylglucosamine sugar attached to serine or threonine residues in nuclear, cytoplasmic, or mitochondrial proteins. Two enzymes cycle O-GlcNAc on or off protein; O-GlcNAc transferase (OGT) adds the modification, and O-GlcNAcase (OGA) removes it. O-GlcNAcylation responds to inputs from multiple metabolic and stress pathways including glucose, amino acid, fatty acid, and nucleotide metabolism. Therefore, O-GlcNAc acts as a sensor of cellular homeostasis able to link environmental conditions with gene transcription; however, decoding the precise function of millions of O-GlcNAc regulated elements remains challenging. Technologies to readily manipulate O-GlcNAcylation at specific cis-regulatory elements for functional analysis without pleiotropic consequences are lacking. We have employed novel CRISPR-based gene targeting tools to probe the function of O-GlcNAc regulated cis-elements. First, we developed a programmable CRISPR-Cas9-based targeting system. This was accomplished by fusing a catalytically dead Cas9 (dCas9) to O-GlcNAc transferase (OGT) or O-GlcNAcase (OGA), which allows for highly specific O-GlcNAc manipulation at chromatin cis-regulatory elements. Previously, we demonstrated that O-GlcNAc plays a role in regulating human A{gamma}-globin gene expression by regulating CHD4 function and the formation of the NuRD (Nucleosome Remodeling and Deacetylase) complex at the -566 GATA repressor-binding site. Thus, as a proof of principle and to further explore the function of O-GlcNAc in{gamma} -globin gene transcription, we targeted both dCas9-OGT and -OGA fusion proteins to the A{gamma}-globin gene promoter. When dCas9-OGT or dCas9-OGA was targeted to the -566 GATA silencer site of the A{gamma}-globin promoter, gene expression decreased or increased, respectively. This data strongly correlates with our previous findings and implicates O-GlcNAc cycling in{gamma} -globin gene regulation. Importantly, this method can be employed to investigate O-GlcNAc events known to exist within the eukaryotic genome in a highly specific manner. Together, this tool will be fundamental in elucidating the function of O-GlcNAc in gene transcription.

biochemistry↗

bioRxiv2020

Updates on enzymatic and structural properties of human glutamine: fructose-6-phosphate amidotransferase 2 (hGFAT2)

Glycoconjugates play a central role in several cellular processes and alteration in their composition is associated to human pathologies. The hexosamine biosynthetic pathway is a route through which cells obtain substrates for cellular glycosylation, and is controlled by the glutamine: fructose-6-phosphate amidotransferase (GFAT). Human isoform 2 GFAT (hGFAT2) has been implicated in diabetes and cancer, however, there is no information about structural and enzymatic properties of this enzyme. Here, we report a successful expression and purification of a catalytically active recombinant hGFAT2 (rhGFAT2) in E. coli cells fused or not to a HisTag at the C-terminal end. Our enzyme kinetics data suggest that hGFAT2 does not follow the ordered bi-bi mechanism, and performs the glucosamine-6-phosphate synthesis much slowly than previously reported for other GFATs. In addition, hGFAT2 is able to isomerase fructose-6-phosphate into glucose-6-phosphate even in presence of equimolar amounts of glutamine, in an unproductive glutamine hydrolysis. Structural analysis of the generated three-dimensional model rhGFAT2, corroborated by circular dichroism data, indicated the presence of a partially structured loop in glutaminase domain, whose sequence is present in eukaryotic enzymes but absent in the E. coli homolog. Molecular dynamics simulations show such loop as the most flexible portion of the protein, which interacts with the protein mainly through the interdomain region, and plays a key role on conformational states of hGFAT2. Altogether, our study provides the first comprehensive set of data on the structure, kinetics and mechanics of hGFAT2, which will certainly contribute for further studies focusing on drug development targeting hGFAT2.

biochemistry↗

bioRxiv2019

Hyperglycemia enhances cancer immune evasion by inducing alternative macrophage polarization through increased O-GlcNAcylation

Diabetes mellitus (DM) significantly increases the risk for cancer and cancer progression. Hyperglycemia is the defining characteristic of DM and tightly correlates with a poor prognosis in cancer patients. The hexosamine biosynthetic pathway (HBP) is emerging as a pivotal cascade linking high glucose, tumor progression and impaired immune function. Here we show that enhanced glucose flow through the HBP drives cancer progression and immune evasion by increasing O-GlcNAcylation in tumor-associated macrophages (TAMs). Increased O-GlcNAc skewed macrophage polarization to a M2-like phenotype. HBP or O-GlcNAcylation inhibition reprogrammed TAMs to an anti-tumoral phenotype. Finally, we found an upregulation of M2 markers on TAMs in DM2 patients with colorectal cancer compared to non-diabetic normoglycemic patients. Our results provide evidence for a new and targetable mechanism of cancer immune evasion in patients with hyperglycemia, advocating for strict control of hyperglycemia in cancer patients.\n\nSignificanceHyperglycemia increases O-GlcNAc levels in TAMs, programing them to a pro-tumorigenic phenotype (M2-like), contributing to cancer progression. Inhibition of O-GlcNAcylation could therefore be used to reprogram intratumoral macrophages to an anti-tumoral phenotype.

cancer biology↗