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PubMedDate not supplied

Development stage-specific expression of fibroin in the silk worm Bombyx mori is regulated translationally.

The contents of fibroin H RNA as a function of development have been quantitated in the posterior silk glands of Bombyx mori larvae on different days of 4th and 5th instars. The fibroin RNA levels increased during the feeding stages of larvae and the RNA got completely degraded during the interim moult. The patterns of accumulation of fibroin RNA were similar in both the instars. Although there was considerable increase in the fibroin RNA content during the 5th larval instar, the relative abundance of fibroin RNA in the total RNA was fairly constant during the 4th and 5th instars. The increased content of fibroin RNA in 5th instar was the consequence of an overall increase in transcription accompanying the development progress, rather than specific increase only in fibroin transcription. The contents of fibroin protein in the 4th and 5th instars of development have also been quantitated making use of a sensitive radioimmune assay with a purified, antifibroin antibody. There were substantial differences between 4th and 5th instars in the absolute fibroin contents as well as the relative proportion of fibroin in the total proteins. These results implied that although the fibroin gene was transcribed at the same efficiency during the 4th and 5th instars, the translational efficiency was much lower during the 4th instar. The extent of polyadenylation of fibroin RNA was similar in both instars. However, there was a two-fold increase in the polysome association of fibroin RNA in the 5th instar. Over and above this, there was substantial increase during the 5th instar in the contents of those tRNAs. (e.g. Gly, Ala and Ser) which are abundantly represented in fibroin and therefore directly related to the expression of fibroin. The increased polysome association of fibroin mRNA and the adequate supply of cognate tRNAs in the 5th instar, together contributes to the translational regulation of fibroin in a developmental stage-specific manner. Based on these observations, we propose that translational regulation plays a major role in the development stage-specific synthesis of fibroin in Bombyx mori.

Animals↗

PubMed2026

Matrix Mechanics Governs Mechano-Metabolic Adaptation across Cancer Grades in Bladder Spheroids.

Extracellular matrix (ECM) mechanics is pivotal regulators of tumor progression, yet how viscoelasticity and matrix architecture converge to shape metabolic and invasive adaptation remains insufficiently defined. We postulate that mechanical stimuli from the ECM induce coordinated changes in adhesive and metabolic pathways, and that the nature of this independent mechano-metabolic pathway is conserved across benign, low-invasive, and high-invasive bladder cancer phenotypes. Therefore, we engineered collagen-hyaluronan hydrogels with tunable stiffness to recapitulate soft and rigid tumor microenvironments and profiled bladder cancer spheroids representing benign, low-invasive, and highly invasive states. Integrating hydraulic force spectroscopy, rheology, and molecular phenotyping, we show that matrix stiffening differentially reprograms spheroid architecture, motility, and adhesion- and metabolism-related gene expression. Spheroid behavior emerged from the interplay between intrinsic mechanical properties, matrix rheology, and molecular adaptation. HCV29 spheroids formed rigid, compact structures, relying on cell-matrix adhesion rather than metabolic or proteolytic remodeling. HT1376 spheroids activated glycolysis (HK2) and MMP-2-dependent ECM remodeling in soft matrices, but remained largely nonmigratory, indicating decoupling of invasive priming from motility. T24 spheroids were soft, deformable, and highly migratory in compliant matrices, integrating metabolic reprogramming, adhesion remodeling (E-/N-cadherin, SDC4), and radial collagen fiber alignment to drive invasion. Notably, canonical FAK/AKT/mTOR signaling was absent across all spheroids, while pS6 ribosomal protein and ILK indicated noncanonical, SDC4/integrin-ILK-dependent mechanotransduction supporting cytoskeletal dynamics, metabolism, and ECM remodeling. Collagen organization further differed across spheroid types, with dense, radially aligned fibers in HT1376, intermediate architecture in HCV29, and loose, disorganized networks in T24, closely matching their distinct migratory behaviors and cell-ECM interactions. These findings reveal stage-specific mechanometabolic strategies in bladder cancer, demonstrating how ECM mechanics and architecture jointly guide invasion, metabolic adaptation, and local immune modulation, including the regulation of immune cell infiltration and tumor immune evasion.

Humans↗

PubMed1990

Ultrastructural correlates of meiotic maturation in mammalian oocytes.

Immature mammalian oocytes reside in ovarian follicles with junctionally coupled granulosa cells. When released from a currently undefined meiotic arresting influence, these oocytes resume meiosis to progress from late diplotene (germinal vesicle stage) through the first meiotic division to metaphase II. Oocytes remain at metaphase II until fertilization activates them to complete meiosis. This review summarizes ultrastructural events that occur during meiotic maturation in mammals. Developmental correlates that promise a clearer understanding of regulatory mechanisms operating to control maturation are emphasized. By use of TEM of thin sections, freeze-fracture analysis, and replicated oocyte cortical patches, we demonstrate stage-specific changes in the oocyte nucleus, reorganization of cytoplasmic organelles, correlations between oocyte maturational commitment and the junctional integrity of associated granulosa cells, and definition of the components comprising the oocyte cortical cytoplasm.

Animals↗

PubMed1986

Stage-specific changes in protein phosphorylation accompanying meiotic maturation of mouse oocytes and fertilization of mouse eggs.

Characteristic changes in the patterns of protein phosphorylation occur during meiotic maturation of mouse oocytes from the time subsequent to germinal vesicle breakdown, through metaphase II, and following fertilization. These changes occur during both in vitro or in vivo maturation or fertilization. Three major classes of changes in total phosphoprotein synthesis are observed. In the first class, protein phosphorylations increase from the germinal vesicle stage until just after germinal vesicle breakdown and then decrease during progression to metaphase II and after fertilization. The second class is characterized by decreases in protein phosphorylation during maturation with subsequent increases in phosphorylation of these proteins after fertilization. The third class is characterized by protein phosphorylations that remain relatively constant during maturation but increase after fertilization; phosphotyrosine phosphoproteins comprise the major species. The radiolabeled protein and phosphoprotein composition of isolated germinal vesicles was also examined, and a phosphoprotein of Mr 29,000 is found exclusively associated with the germinal vesicle. Since we have shown previously that 12-O-tetradecanoyl phorbol 13-acetate inhibits fertilization (Y.Endo, R.M. Schultz, and G.S. Kopf, submitted), we examined the effects of this compound on the phosphoprotein patterns of metaphase II eggs. 12-O-Tetradecanoyl phorbol 13-acetate treatment stimulates the phosphorylation of a specific phosphoprotein of Mr 80,000.

1-Methyl-3-isobutylxanthine↗

PubMed1990

Stage-specific expression of the lactate dehydrogenase-X gene in adult and developing mouse testes.

Lactate dehydrogenase-X (LDH-X), a glycolytic enzyme found only in mammalian testes and spermatozoa, is encoded by a single gene (Ldh-x) in the mouse haploid genome. Several studies have demonstrated that LDH-X is associated with germ cells at specific stages of development. We have examined the expression of the Ldh-x gene during mouse spermatogenesis and testis maturation using in situ mRNA hybridization and immunocytochemistry. The results showed that transcription and translation of the Ldh-x gene are initiated at the pachytene stage of germ cell differentiation. However, although the amount of LDH-X protein increased as the germ cells progressed to maturation, its mRNA level was greatly decreased. These observations were confirmed by Northern analysis of total RNA derived from fractionated spermatogenic cells and developing testes. Furthermore, Northern studies also indicated two sizes of Ldh-x transcripts among different populations of spermatogenic cells in mature mouse testis.

Animals↗

PubMed1992

Stage-specific expression of rat transition protein 2 mRNA and possible localization to the chromatoid body of step 7 spermatids by in situ hybridization using a nonradioactive riboprobe.

The present study has used methoxyacetic acid (MAA)-induced depletion of specific germ cell types in the rat and in situ hybridization with nonradioactive riboprobes to determine the stages of the spermatogenic cycle at which there is expression of the mRNA for the basic chromosomal protein transition protein 2 (TP2). On Northern blots, an abundant mRNA was detectable in samples from control adult rats, but the amount of message was markedly reduced when RNA was extracted from the testes of rats treated 14 and 21 days previously with methoxyacetic acid. These testes were depleted specifically of step 7-12 spermatids, suggesting that these cells contain TP2 mRNA. When tissue sections were subjected to in situ hybridization, the TP2 mRNA was localized at the cellular and subcellular levels. Messenger RNA for TP2 was first detectable in spermatids at step 7. In these spermatids, at high magnification, in addition to some positive reaction in the cytoplasm, intense staining was located to a perinuclear structure consistent with localization of mRNA within the chromatoid body. The amount of TP2 mRNA in the cytoplasm increased as remodelling of the early spermatid nucleus progressed and was highest in step 10 and 11 spermatids at stages X and XI. Thereafter, the mRNA decreased until it was undetectable in step 14 spermatids at stage XIV. The localization of TP2 mRNA to the chromatoid body of step 7 spermatids would be consistent with this organelle being a storage site for long-lived mRNAs utilized later in spermiogenesis.

Animals↗

PubMed1988

Changes in heat shock protein synthesis and hsp70 gene transcription during erythropoiesis of Xenopus laevis.

As erythroid cells of Xenopus laevis differentiate, their capacity for transcription and protein synthesis becomes progressively restricted. Mature erythrocytes are thought to be transcriptionally inert and have very low levels of protein synthesis (Maclean et al., 1973, Cell Differ. 2, 261-269). We have examined actual and potential synthetic activity during erythropoiesis by comparing the patterns of protein synthesis and measuring the transcriptional activity of selected genes under ambient and heat shock conditions. As erythropoiesis proceeds, there is a progressive decrease in the number of heat shock proteins (hsps) whose synthesis is induced at elevated temperatures. Despite this repression, mature erythrocytes are able to respond to heat shock with the induction of synthesis of one protein, hsp70. In addition, an hsp70-like protein is synthesized constitutively in orthochromatic erythroblasts, the final erythroid cell stage before maturation into erythrocytes. An in vitro nuclear run-off transcription assay was used to study transcription of the hsp70, beta-globin, and ribosomal genes during erythropoiesis. beta-Globin and ribosomal gene transcription were detected at all stages of erythropoiesis, including the erythrocyte stage. However, transcription of the beta-globin gene relative to ribosomal gene transcription declines substantially in erythrocytes as compared to earlier stages. Hsp70 gene transcription shows both stage-specific and heat shock-dependent transcription. Orthochromatic erythroblasts and erythrocytes have heat shock-dependent hsp70 gene transcription, whereas the gene is transcribed at the earlier erythroblast stages at ambient temperature as well as during heat shock. The constitutive hsp70 transcripts made during these earlier stages may be stored for utilization in constitutive synthesis of the hsp70-like protein in orthochromatic erythroblasts. These data indicate that although erythrocytes become synthetically repressed during differentiation, they are less inert than previously thought. The data also reveal that the synthesis of hsps and related proteins is subject to both transcriptional and post-transcriptional control during erythropoiesis.

Animals↗

PubMed1991

Meiotic competence acquisition is associated with the appearance of M-phase characteristics in growing mouse oocytes.

To determine whether the acquisition of meiotic competence during the growth phase of oogenesis is associated with the appearance of M-phase characteristics, oocytes obtained from 13- to 30-day-old mice were evaluated by fluorescence microscopy with respect to chromatin and microtubule organization , in vitro maturation ability, and the distribution of M-phase phosphoproteins. Meiotically incompetent oocytes were distinguished from their competent counterparts in displaying elaborate interphase-like arrays of cytoplasmic microtubules and dispersed germinal vesicle chromatin. Meiotically competent oocytes were larger in size, exhibited condensation of chromatin around the nucleolus, and displayed a progressive diminution of cytoplasmic microtubules in conjunction with the appearance of multiple microtubule organizing centers. After 24 hr in culture, medium- to large-sized oocytes exhibiting perinucleolar chromatin condensation resume meiosis whereas smaller meiotically incompetent oocytes retain GVs with diffuse chromatin. Moreover, indirect immunofluorescence studies using the M-phase phosphoprotein specific monoclonal antibody MPM-2 indicate that the appearance of reactive cytoplasmic foci is directly correlated with nuclear changes characteristic of meiotically competent oocytes. Thus, the earliest transition to a meiotically competent state during oocyte growth in the immature mouse ovary is characterized by stage-specific and coordinated modifications of nuclear and cytoplasmic components.

Animals↗

PubMed1987

A murine monoclonal antibody strictly reactive with human peripheral blood monocytes.

We have produced and characterized a novel murine monoclonal antibody (LAM7) of IgG1 isotype which appears specific for peripheral blood monocytes (PBM) on the basis of histochemical and functional studies. By indirect immunofluorescence, including FACS analysis, the antibody reacts with 90 +/- 6% of PBM and with monocytic leukemias, while it is totally unreactive with B and T lymphocytes, platelets, granulocytes, peripheral macrophages, dendritic cells, large granular lymphocytes, and nonmonocytic leukemias. The antigen-presenting capacity of peripheral blood mononuclear cells is abolished by treatment with MoAb LAM7 in an antiglobulin-complement-mediated cytotoxicity test, and restored by addition of purified PBM. The progressive disappearance of the antigen recognized by LAM7 from PBM within approximately 3 days in culture, and its absence from both bone marrow precursors and tissue macrophages, define it as a line-specific and stage-specific differentiation.

Animals↗

PubMed1991

Expression of two nonallelic type II procollagen genes during Xenopus laevis embryogenesis is characterized by stage-specific production of alternatively spliced transcripts.

The pattern of type II collagen expression during Xenopus laevis embryogenesis has been established after isolating specific cDNA and genomic clones. Evidence is presented suggesting that in X. laevis there are two transcriptionally active copies of the type II procollagen gene. Both genes are activated at the beginning of neurula stage and steady-state mRNA levels progressively increase thereafter. Initially, the transcripts are localized to notochord, somites, and the dorsal region of the lateral plate mesoderm. At later stages of development and parallel to increased mRNA accumulation, collagen expression becomes progressively more confined to chondrogenic regions of the tadpole. During the early period of mRNA accumulation, there is also a transient pattern of expression in localized sites that will later not undergo chondrogenesis, such as the floor plate in the ventral neural tube. At later times and coincident with the appearance of chondrogenic tissues in the developing embryo, expression of the procollagen genes is characterized by the production of an additional, alternatively spliced transcript. The alternatively spliced sequences encode the cysteine-rich globular domain in the NH2-propeptide of the type II procollagen chain. Immunohistochemical analyses with a type II collagen monoclonal antibody documented the deposition of the protein in the extracellular matrix of the developing embryo. Type II collagen expression is therefore temporally regulated by tissue-specific transcription and splicing factors directing the synthesis of distinct molecular forms of the precursor protein in the developing Xenopus embryo.

Amino Acid Sequence↗

PubMed1992

In vivo stage- and tissue-specific DNA-protein interactions at the D. melanogaster alcohol dehydrogenase distal promoter and adult enhancer.

We performed a high resolution analysis of the chromatin structure within the regions required for distal transcription of the Drosophila melanogaster alcohol dehydrogenase gene (Adh). Using dimethyl sulfate, DNase I, and micrococcal nuclease as structural probes, and comparing chromatin structure in tissues isolated from several developmental stages, we have identified several sites of stage- and tissue-specific DNA-protein interactions that correlate with distal transcription initiation. Most were within previously identified cis-acting elements and/or in vitro protein binding sites of the adult enhancer (AAE) and distal promoter, including the TATA box. We also detected a novel stage-specific DNA-protein interaction at the Adf-2a binding site where a non-histone protein was bound to the DNA on the surface of a positioned nucleosome previously identified between the distal promoter and adult enhancer. In addition to footprints, we have also revealed stage- and tissue-specific DNA helix deformations between many of the non-histone protein binding sites. These helix distortions suggest there are interactions among the adjacently bound proteins that result in bending or kinking of the intervening DNA. The distal promoter and AAE have an accessible chromatin conformation in fat body prior to the third larval instar and many of the regulatory proteins that bind in these regions are also available before distal transcription begins. Nevertheless, the timing of DNA-protein interactions in the distal promoter and AAE suggest these proteins do not bind individually or assemble progressively as they and their binding sites become available. Instead, there appears to be a coordinated assembly of a large cooperative complex of proteins interacting with the distal promoter, the positioned nucleosome, the enhancer of the distal promoter (the AAE), and each other.

Alcohol Dehydrogenase↗

PubMed2025

Proteomic profiling identifies miR-423-5p as a modulator of oncogenic metabolism in HCC.

BACKGROUND: Hepatocellular carcinoma (HCC) remains a significant clinical challenge due to limited diagnostic and therapeutic options. Non-coding RNAs (ncRNAs), such as microRNAs (miRNAs), play key roles in cancer biology. Our previous findings showed that miR-423-5p enhances anti-cancer effects on HCC patients treated with sorafenib by promoting autophagy. Here, we investigated the molecular mechanisms underlying miR-423-5p function through a comprehensive proteomic approach. METHODS: We generated an HCC cell line stably overexpressing miR-423-5p via lentiviral transduction. Total proteins were extracted from SNU-387 cells, enzymatically digested into peptides, and subsequently analysed by liquid chromatography-tandem mass spectrometry (LC-MS/M). Raw spectral data were processed and quantified using MaxQuant. Differentially expressed proteins (DEPs) were defined based on fold-change (|log2FC| ≥ 1) and false discovery rate (FDR < 0.05). The full proteomic dataset is available via the ProteomeXchange repository (identifier: PXD064869). Functional enrichment analysis of DEPs were performed using DAVID and Reactome. To assess clinical relevance, predicted and validated miR-423-5p targets were integrated with The Cancer Genome Atlas (TCGA) Liver Hepatocellular Carcinoma (LIHC) dataset using GEPIA platform. Survival analyses were performed using the Kaplan-Meier method. RESULTS: Proteomic profiling identified 698 DEPs in miR-423-5p-overexpressing cells compared to controls with significant enrichment in metabolic pathways, related to purine/pyrimidine metabolism and gluconeogenesis. Integration with bioinformatic predictions and miRTarBase validation identified 43 DEPs as potential direct targets of miR-423-5p. Among these, seven proteins (ACACA, ANKRD52, DVL3, MCM5, MCM7, RRM2, SPNS1, and SRM) were significantly associated with patient prognosis in the TCGA-LIHC cohort. These targets were downregulated in miR-423-5p-overexpressing cells but upregulated in advanced-stage HCC tissues, suggesting a potential role for miR-423-5p in the regulation of HCC pathogenesis. Stage-specific expression analysis showed increased levels from stage I to III, followed by a decline at stage IV. Notably, we experimentally confirmed miR-423-5p-mediated suppression of MCM7, DVL3, IMPDH1, and SRM (SPEE), supporting their functional involvement in HCC progression. CONCLUSION: Overall, our findings support a tumour-suppressive role for miR-423-5p in HCC, mediated by modulation of metabolic pathways and suppression of oncogenic proteins. These results suggest that miR-423-5p and its downstream effectors may serve as promising biomarkers and potential therapeutic targets in HCC. HIGHLIGHTS: miR-423-5p acts as a tumor suppressor in HCC by targeting key nodes of pro-tumorigenic signalling. miR-423-5p significantly altered metabolic pathways, including purine/pyrimidine metabolism and gluconeogenesis. Seven miR-423-5p targets correlate with poor prognosis in TCGA-LIHC patients and are downregulated in miR-423-5p overexpressing HCC cells. miR-423-5p over-expression induces a significant downregulation of MCM7, DVL3, IMPDH1, SPEE in HCC cell models. miR-423-5p limits tumor metabolic plasticity, suggesting therapeutic potential.

MicroRNAs↗

PubMed1991

In vitro stimulation of stage-specific deoxyribonucleic acid synthesis in rat seminiferous tubule segments by interleukin-1 alpha.

Levels of rat testicular interleukin-1-like factor (tIL-1) have been shown to correlate with DNA synthetic activity during the cycle of the rat seminiferous epithelium, suggesting its role as a spermatogonial or meiotic growth factor. To explore this further, a new in vitro model system was developed. Rat seminiferous tubule segments from stages I, V, VIIa, and VIII-IX of the cycle were isolated by transillumination-assisted microdissection, cultured in chemically defined serum-free medium supplemented with human recombinant IL-1 alpha, and labeled with [3H]thymidine. During incubation, spontaneous progression of spermatogenesis was noted. Inactive stage VIIa tubule segments differentiated to stage VIII and initiated DNA synthesis, and concomitantly started to secrete IL-1-like factor. DNA synthesis of stages VIII-IX ceased through differentiation of spermatocytes to leptotene-zygotene (stages XII-XIII of the cycle). IL-1 alpha stimulated DNA synthesis significantly in spermatogonia of stage I. Meiotic DNA synthesis at stage VIIa was stimulated (48 h/34 C) and maintained at stages VIII-IX (48 h/34 C). IL-1 alpha seems to act as a regulator of spermatogenic DNA synthesis in both mitotic and meiotic phases. It has mainly stimulating and maintaining effects, but it may also be inhibitory under certain conditions.

Animals↗

PubMed1991

Centrosome and microtubule dynamics during meiotic progression in the mouse oocyte.

The disposition, function and fate of centrosomes were analysed in mouse oocytes undergoing in vitro meiotic maturation, using multiple-label fluorescence microscopy. Oocytes fixed at various points during meiotic progression were double labeled with either human centrosome-specific antibody, 5051, and anti-tubulin antibodies or 5051 and MPM-2 antibodies in order to evaluate the microtubule nucleation capacity and phosphorylation status of centrosomes during this process. Double labeling with anti-tubulin antibodies revealed two populations of centrosomes that undergo stage-specific changes in number, location and microtubule nucleation capacity in relation to spindle assembly and cytoplasmic events. Specifically, one population was consistently associated with chromatin throughout meiotic maturation whereas a second population of cytoplasmic centrosomes exhibited maximal numbers and nucleation capacity at prometaphase and anaphase of meiosis-I. Quantitative evaluation of cytoplasmic centrosomes indicated increased numbers during the transition from diakinesis to prometaphase and metaphase to anaphase and total disappearance during telophase. Colocalization studies with MPM-2 revealed that centrosomes were always phosphorylated. However, at metaphase of meiosis I and II the microtubule nucleation capacity of centrosomes was diminished. These results suggest the existence of two discrete populations of centrosomes in the mouse oocyte that are coordinately regulated to subserve aspects of microtubule organization relative to both nuclear and cytoplasmic events.

Anaphase↗

PubMed1992

Stage-specific tyrosine phosphorylation of actin in Dictyostelium discoideum cells.

A 45 kDa protein in Dictyostelium discoideum cells that was recognized by a phosphotyrosine-specific antibody was identified by its binding activity to DNase I and its 2D-electrophoretic behavior as actin. The reactivity of actin with the antibody was transiently enhanced for about 30 minutes shortly after starving cells were reintroduced into nutrient medium. This effect indicates a modification of actin that is regulated under physiological conditions. A similar effect was obtained when growing cells were treated with phenylarsine oxide (PAO), an inhibitor of phosphotyrosine phosphatases. This effect was reversed and the cells fully recovered upon addition of the PAO antagonist 2,3-dimercaptopropanol. Starved cells did not show this enhancement of antibody labelling, which indicates that the response to PAO depends on the developmental stage. Phosphorylated amino acid residues were identified after in vivo labelling with [32P]phosphate in the presence of PAO. Part of the radioactivity in the actin band was recovered as phosphotyrosine, another part as phosphoserine. PAO caused the cells to form elongated blebs, to round up and finally to become immobilized. Fluorescence labelling with phalloidin of cells that were fixed at different times of PAO treatment revealed a progressive decrease in the staining for actin filaments and showed that these alterations in cytoskeleton organization were readily reversible, in accordance with the reversal of tyrosine phosphorylation at actin.

Actins↗

PubMed1991

Stage-specific ultrastructural effects of desferrioxamine on Plasmodium falciparum in vitro.

Desferrioxamine (DFO) is an iron chelator that inhibits the in vitro and in vivo growth of rodent and human malarial parasites. Previous studies with this chelator have suggested that it might interfere with the intraerythrocytic growth of Plasmodium sp. by withholding iron from any of several essential iron-dependent parasite enzymes, including those involved in CO2 fixation, mitochondrial electron transport, pyrimidine synthesis, and the reduction of ribonucleotides for DNA synthesis. We studied the ultrastructural effects of DFO on synchronized cultures of P. falciparum to identify the specific site of action of this compound. Synchronized cultures of early rings or schizonts were exposed to 100 microM DFO for up to 48 hr, and fixed and processed at regular intervals for electron microscopy. Untreated cultures and cultures exposed to DFO saturated with Fe3+ were processed at the same time. When DFO was added to synchronized cultures containing early rings, parasites developed normally until the late trophozoite stage, when all growth ceased. Ultrastructural lesions included the breakdown of the nuclear envelope into small membranous fragments and progressive vacuolization of the nucleoplasm. Other organelles, including food vacuoles and mitochondria, were not affected. The addition of DFO to synchronized cultures of schizonts had similar effects on nuclei of early schizonts, but little or no effect on mature schizonts and segmenters. Erythrocyte invasion by merozoites proceeded in the presence of the chelator. These findings support the hypothesis that DFO acts specifically during the late trophozoite/early schizont stage of parasite maturation by preventing nuclear division, an effect consistent with inhibition of the iron-dependent enzyme ribonucleotide reductase.

Animals↗

PubMed2026

Proteomic Analysis of Extracellular Vesicles Reveals Vitronectin and Laminin Subunit Alpha-3 as Candidate Biomarkers for Gastric Cancer.

BACKGROUND/AIMS: Clinically useful noninvasive biomarkers for gastric cancer remain limited. Extracellular vesicles (EVs) carry a molecular cargo reflective of their cells of origin and have emerged as promising candidates for blood-based cancer biomarkers. We aimed to identify EV-associated protein biomarkers for gastric cancer via a proteomic approach. METHODS: Proteomic profiling of EVs was performed using one normal gastric cell line (Hs738st/int) and two gastric cancer cell lines (AGS and NCI-N87). Selected proteins were validated in blood-derived EVs isolated from plasma samples of 10 healthy controls and 36 patients with gastric cancer. RESULTS: Proteomic analysis identified 224 differentially expressed proteins whose expression was consistently altered in gastric cancer cell line-derived EVs. Among these, vitronectin (VTN) and laminin subunit alpha-3 (LAMA3) were selected based on their consistent upregulation. EV-associated LAMA3 levels were significantly higher in patients with gastric cancer than in healthy controls (p=0.003), with significant elevations observed from stage II onward (p=0.041, p=0.017, and p=0.004 for stages II, III, and IV, respectively). EV-associated VTN levels were not significantly different overall (p=0.089); however, stage-specific analysis demonstrated significant increases in VTN levels in patients with stage III (p=0.036) and stage IV (p=0.005) gastric cancer. Both EV-associated VTN and LAMA3 levels showed significant positive correlations with the cancer stage (ρ=0.564 and ρ=0.611, respectively; both p<0.001). CONCLUSIONS: The levels of EV-associated VTN and LAMA3 appear to be more closely associated with disease progression than with early-stage detection of gastric cancer. These findings suggest that EV-based proteomic biomarkers may have clinical utility for monitoring tumor progression in patients with clinically advanced gastric cancer.

Humans↗

PubMed1990

Stage-specific ribosomal RNA expression switches during sporozoite invasion of hepatocytes.

Two structurally distinct ribosomal RNAs (rRNAs) occur in different developmental stages of malaria parasites. One point at which the transition from one type to the other is found shortly after sporozoites invade hepatocytes, the first stage of parasite development in the mammalian host. The invasion in itself appears necessary but insufficient to trigger the rRNA transition. The progression of events involved in the synthesis of a new type ribosome is tied to the fate of the invading parasite. Interestingly, the switch also occurs in irradiated sporozoites. The new rRNAs produced are processed to the mature size, indicating that rRNA transcription and processing remain normal in the attenuated parasites. These results have implications for monitoring antimalaria vaccine candidates and drug efficacy.

Animals↗