Biology subjects

Almeida, I. C.

Publications and source records attributed to Almeida, I. C..

6 recordsLinked to original sources

bioRxiv2026

Stress-Survival Pathway Profiling Reveals MCM10 as a Candidate Biomarker of Hispanic Colorectal Cancer Disparities

BackgroundColorectal cancer (CRC) remains the second leading cause of cancer mortality in the U.S., with significant racial and ethnic disparities in incidence, survival, and mortality rates. The rising incidence of early-onset CRC and the frequent presentation at advanced stages of CRC among the Hispanics makes this an important ethnic group to study. A deeper understanding of the complex interplay between molecular, genetic, and environmental factors is critical for developing targeted therapies to reduce the prevalence in specific racial and ethnic groups, such as Hispanics. This study explores the role of stress-survival pathway (SSP) genes in early-onset and late-stage CRC, primarily focusing on disparities between Hispanics and Non-Hispanic Whites (NHWs). Additionally, this study investigates the role of MCM10, in contributing to CRC disparities among the Hispanic populations with an emphasis of early-onset and late-stage CRC Hispanics. MethodsOne of our previous studies had identified some SSP protein coding genes associated with CRC. The transcript and protein level expressions of these genes were validated in CRC cell lines, cDNA arrays, and tissue microarrays, using qRT-PCR and immunohistochemistry, respectively. The transcript level expressions of differentially expressed SSP genes were further evaluated in Hispanic and NHWs tumor tissues, including early onset and late-stage cohorts. Additionally, we performed cellular, physiological, and functional assays to explore the role of MCM10 in tumor progression, before and after siRNA mediated knockdown of MCM10. High-throughput transcriptomic and proteomic analyses were performed to reveal the underlying molecular mechanism. ResultsWe observed the differential expressions of twelve SSP genes in CRC cell lines, at the transcript level; that of ten genes in early and late stages using cDNA arrays, and nine genes at the protein levels using tissue microarrays and immunohistochemistry. Hispanic CRC samples showed differential expression of all nine SSP genes compared to NHWs, in early-onset, and late-stage CRC, with all genes being upregulated other than CDK4 and PRDX4 in late-stage CRC and CDK4 in early-onset CRC. Our functional study demonstrated that MCM10 knockdown in CRC cell lines significantly reduced cell proliferation, growth, invasion, and migration by inducing cell cycle arrest, apoptosis, and reactive oxygen species pathways. The integrative RNA-sequencing and proteomics study identified that PPFIA1 could be associated with MCM10 mediated cancer progression. The role of MCM10 and PPFIA1 in cancer progression has also been validated by CRISPR-Cas9 mediated MCM10 knock out, using a Hispanic CRC patient derived organoid. ConclusionThe differential expression of SSP genes suggest a potential molecular contribution to CRC disparities in the Hispanic population. The essential oncogenic role of MCM10 and its axis with PPFIA1 was identified; this could lead to a new avenue for therapeutics targeting the MCM10-PPFIA1 axis, thereby, combating early-onset and advanced-stage CRC in this high-risk ethnic group. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=177 HEIGHT=200 SRC="FIGDIR/small/698057v2_ufig1.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@11528c8org.highwire.dtl.DTLVardef@288d15org.highwire.dtl.DTLVardef@466703org.highwire.dtl.DTLVardef@150890_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2025

Molecular Mechanisms of Priming Innate Immunity by Small Extracellular Vesicles Released during Infection with Gram-negative Bacteria

Much still remains to understand about the underlying molecular mechanisms by which the trafficking of small extracellular vesicles (sEVs) modulates innate immune responses during infection with pathogenic Gram-negative bacteria. To address this significant gap in knowledge, we used two infection models to investigate innate immune regulation by the sEVs released from cells infected with either Yersinia pestis (Yp) or Burkholderia thailandensis (Bt), designated as EXi-Yp and EXi-Bt respectively. The EXi induced differentiation of naive human monocytes to macrophages and triggered robust pro-inflammatory cytokine release, including release of IL-6, mirroring direct bacterial infection effects. Comprehensive cell signaling analyses revealed that the EXi modulate a small set of host signaling proteins, with p38 activation being primarily responsible for the observed protective effects. EXi-induced p38 activation leads to increased IL-6 release, which in turn is responsible for decreased bacterial survival within recipient immune cells that are subsequently infected. Consistent with the in vitro results, mice administered with EXi-Yp exhibited elevated serum IL-6 levels and were protected from Yp infection. Furthermore, using our microfluidic chip platform that allows functional interrogation of EV effects under physiologically relevant conditions, we have demonstrated that EXi exchange between Yp-infected cells and naive recipient monocytes leads to differentiation of the recipient cells to macrophages. Together, our findings reveal a largely unexplored aspect of innate immunity and provide a mechanistic model in which EXi prime local and distant naive monocytes via p38-induced differentiation and IL-6 production to protect against infection with Gram-negative bacteria.

immunology↗

bioRxiv2023

Blood prognostic biomarker signatures for hemorrhagic cerebral cavernous malformations (CCMs)

BackgroundCerebral cavernous malformations (CCMs) is a neurological disorder that causes enlarged intracranial capillaries in the brain, leading to an increased risk of hemorrhagic strokes, which is a leading cause of death and disability worldwide. ObjectivesThe current treatment options for CCMs are limited, highlighting the need for prognostic biomarkers to predict the risk of hemorrhagic events to better inform treatment decisions and identify future pharmacological targets. Eligibility CriteriaThe study is centered on a comparative proteomic analysis between hemorrhagic CCMs (HCs) and healthy controls, while excluding patients with non-hemorrhagic CCMs (NHCs) from the analysis due to the experimental design. Sources of EvidenceRecent research has identified several serum biomarkers and blood circulating biomarkers in a selected cohort of homogeneous CCM patients and animal models. MethodProteomic profiles from both human and mouse CCM models were examined, and pathway enrichment analyses were performed using three approaches (GO, KEGG, and DOSE). To account for multiple comparisons, t-tests were employed to evaluate differences. A p-value below 0.05 was deemed statistically significant. ResultsThe authors have developed the first panel of candidate biomarker signatures, featuring both etiological and prognostic markers in two distinct pathways. This panel of biomarker signatures demonstrates a robust correlation with the likelihood of hemorrhagic CCMs. ConclusionsThis groundbreaking biomarker panel paves the way for further investigation of potential blood biomarkers to determine the risk of hemorrhagic CCMs.

genomics↗

bioRxiv2022

Fatty acid elongases 1-3 have distinct roles in mitochondrial function, growth and lipid homeostasis in Trypanosoma cruzi.

Trypanosomatids are a diverse group of uniflagellate protozoa that include globally important pathogens such as Trypanosoma cruzi, the causative agent of Chagas disease. Trypanosomes lack the fatty acid synthase (FAS)-I system typically used for de novo synthesis of long chain fatty acids (LCFA) in other eukaryotes. Instead, these microbes have evolved a modular fatty acid elongase (ELO) system comprised of individual ELO enzymes that operate processively. The role of the ELO system in maintaining lipid homeostasis in trypanosomes has not been determined. Here we demonstrate that ELO2 and ELO3 are required for global lipidome maintenance in the insect stage of T. cruzi whereas ELO1 is dispensable for this function. Instead, ELO1 activity is needed to sustain mitochondrial activity and normal growth. The cross-talk between microsomal ELO1 and the mitochondrion is a novel finding that merits examination of the trypanosomatid ELO pathway as critical for central metabolism.

microbiology↗

bioRxiv2021

Extracellular vesicles regulate yeast growth, biofilm formation, and yeast-to-hypha differentiation in Candida albicans

The ability to undergo morphological changes during adaptation to distinct environments is exploited by Candida albicans and has a direct impact on virulence. In this study, we investigated the influence of fungal extracellular vesicles (EVs) during yeast growth, biofilm formation, and morphogenesis in C. albicans. Addition of C. albicans EVs (Ca EVs) to the culture medium positively affected yeast growth. Using crystal violet staining and scanning electron microscopy (SEM), we demonstrated that Ca EVs inhibited biofilm formation by C. albicans in vitro. By time-lapse microscopy and SEM, we showed that Ca EV-treatment stops filamentation promoting pseudohyphae formation with multiple sites for yeast budding. The ability of Ca EVs to regulate dimorphism was further compared to EVs isolated from different C. albicans strains, Saccharomyces cerevisiae, and Histoplasma capsulatum. Ca EVs from distinct strains robustly inhibited yeast-to-hyphae differentiation with morphological changes occurring in less than 4 hours. A minor inhibitory effect was promoted by EVs from S. cerevisiae and H. capsulatum only after 24 hours of incubation. The inhibitory effect of Ca EVs was promoted by a combination of lipid compounds identified by gas chromatography-tandem mass spectrometry analysis as sesquiterpenes, diterpenes, and fatty acids. Remarkably, Ca EVs were also able to reverse filamentation, transforming hyphal growth to yeast forms. Transcriptomic analysis demonstrated that treatment with Ca EVs modified the expression of more than 300 genes. The most effectively upregulated pathways were related to DNA metabolism. The downregulated genes were mostly associated with extracellular and adhesion proteins. Finally, yeast cells treated with Ca EVs for 24 hours lost their agar invasive ability and were avirulent when inoculated in Galleria mellonella larvae. In summary, our results indicate that fungal EVs can profoundly modify C. albicans growth and regulate yeast-to-hypha differentiation inhibiting biofilm formation and virulence.

microbiology↗

bioRxiv2018

The crystal structure and localization of Trypanosoma brucei invariant surface glycoproteins suggest a more permissive VSG coat in the tsetse-transmitted metacyclic stage

Trypanosoma brucei spp. develop into mammalian-infectious metacyclic trypomastigotes inside the tsetse salivary glands. Besides acquiring a variant surface glycoprotein (VSG) coat, nothing is known about expression of invariant surface antigens by the metacyclic stage. Proteomic analysis of saliva from T. brucei-infected flies revealed a novel family of hypothetical GPI-anchored surface proteins herein named Metacyclic Invariant Surface Proteins (MISP). MISP are encoded by five homolog genes and share ~80% protein identity. The crystal structure of MISP N-terminus at 1.82 [A] resolution revealed a triple helical bundle that shares key features with other trypanosome surface proteins. However, molecular modelling combined with live fluorescent microscopy suggest that MISP N-termini are extended above the metacyclic VSG coat, exposing immunogenic epitopes. Collectively, we suggest that the metacyclic cell surface architecture appears more permissive than bloodstream forms in terms of expression of invariant GPI-anchored glycoproteins, which could be exploited for the development of novel vaccines against African trypanosomiases.

microbiology↗