Search Results (90)

Objectives: The study aimed to evaluate the effects of full-fat rice bran (FFRB; Tainung No. 81, Taiwan) at various doses on insulin resistance, muscle atrophy, and gut microbiota composition in middle-aged ovariectomized (OVX) mice fed a high-fat diet (HFD), using young sham-operated mice as a life-stage reference group. Methods: Thirty-six female ICR mice were assigned to six groups, including OVX mice fed HFD with or without 5%, 10%, or 20% FFRB. Results: Compared with HFD-fed OVX controls, 20% FFRB reduced body weight gain by 43%, decreased visceral fat mass, and improved insulin resistance (homeostasis model assessment of insulin resistance, HOMA-IR reduced by 65%, P_trend = 0.001). FFRB attenuated the decline in relative grip strength (forelimb, P_trend = 0.013; four-limb, P_trend < 0.001), and upregulated muscle protein synthesis genes, including insulin receptor substrate 1 (IRS-1), mammalian target of rapamycin (mTOR), eukaryotic translation initiation factor 4E binding protein 1 (eIF-4EBP1), while downregulating forkhead box protein O1 (FOXO1), muscle RING-finger protein-1 (MuRF-1), and interleukin (IL)-6. FFRB was also associated with higher fecal acetate levels (P_trend < 0.001), upregulated colonic tight junction genes (occludin and zonula occludens (ZO)-1), and greater relative abundance of g_Muribaculum. Correlation analyses revealed positive associations between short-chain fatty acids (SCFAs) and muscle strength, muscle anabolic markers, genus Lachnospiraceae_UCG_001, and Muribaculum. Conclusions: Dietary inclusion of FFRB was associated with favorable metabolic and muscle-related parameters in HFD-fed middle-aged OVX mice, with potential involvement of gut microbiota and SCFA alterations. Full article

It has been known for decades that eukaryotic cellular mRNAs are frequently translated by multiple ribosomes organized into polysomes of diverse topology, including circular arrangements. The closed-loop model, in which the 5′ cap and 3′ poly(A) tail are bridged by initiation factors, provided a mechanistic basis for mRNA circularization and suggested that the spatial proximity of termini facilitates ribosome recycling. Various biochemical, structural, and imaging approaches—including electron microscopy, atomic force microscopy, cryo-electron tomography, and single-molecule fluorescence—have since demonstrated that polysomes indeed adopt compact and heterogeneous conformations, with circular assemblies representing a significant fraction. Although direct visualization of ribosome recycling remains technically challenging, ribosome turnover experiments, kinetic analyses and modeling support the concept of closed-loop-assisted reinitiation (CLAR), whereby terminating ribosomes are re-utilized to sustain translation efficiency. Together, the findings suggest that mRNA circularization is a dynamic and regulated state that enhances protein synthesis under specific conditions, while linear or modular polysome architectures may dominate in others. Understanding the balance between these modes of translation remains central to elucidating the interplay between mRNA topology, ribosome dynamics, and translational control. Full article

The described features of dinoflagellate gene expression indicate the predominance of post-transcriptional and translational regulation over transcriptional control. These microorganisms also exhibit extensive RNA editing and distinctive splicing characteristics. This regulatory landscape underscores the central role of RNA-binding proteins in dinoflagellate biology. In this review, we summarize current knowledge on major RNA-binding protein groups identified or bioinformatically annotated in dinoflagellates, including RNA recognition motif domain-containing proteins, Sm and Sm-like family, KH domain-containing proteins, zinc-finger proteins, and Pumilio family proteins, S1 domain-containing and cold shock domain-containing proteins, DEAD/DEAH-box RNA helicases, and pentatricopeptide repeat proteins. We focus on the features of their conserved domains, their functions in eukaryotes, and available data on their presence and putative roles in dinoflagellate cells. Integrating genomic, transcriptomic, and proteomic evidence, and where possible experimental data, we highlight both their overall conservation and potential lineage-specific traits. Our aim is to provide a concise synthesis of current knowledge, identify key uncertainties, and outline promising directions for future research into the evolution and cellular roles of RNA-binding proteins in this ecologically and biologically remarkable group. Full article

Glycine has the greatest rate of deposition in whole-body proteins among all amino acids in neonates, but its provision from sow’s milk meets only 20% of the requirement of suckling piglets. The results of our recent studies indicate that piglets with intrauterine growth restriction (IUGR) have a reduced ability to synthesize glycine. The present study determined the role of glycine in the growth of sow-reared IUGR piglets. In Experiment 1, 56 newborn piglets (postnatal day 0) with a low birth weight (<1.10 kg) were selected from 14 litters, providing 4 IUGR piglets/litter that were allotted randomly into one of four treatment groups (14 piglets/group). Piglets received oral administration of either 0, 0.1, 0.2 or 0.4 g glycine/kg body weight (BW) twice daily (i.e., 0, 0.2, 0.4 or 0.8 g glycine/kg BW/day) between 0 and 14 days of age. L-Alanine was used as the isonitrogenous control. The BWs of all piglets were recorded each week during the experiment. Two weeks after the initiation of glycine supplementation, blood and tissue samples were collected for biochemical analyses. In Experiment 2, rates of muscle protein synthesis in tissues were determined on day 14 using the ³H-phenylalanine flooding dose technique. Compared with piglets in the control group, oral administration of 0.2, 0.4 and 0.8 g glycine/kg BW/day did not affect their milk intake (p > 0.05) but increased (p < 0.05) concentrations of glycine in plasma by 1.52-, 1.94-, and 2.34-fold, respectively, and body weight by 20%, 37%, and 34%, respectively. The dose of 0.4 g glycine/kg BW/day was the most cost-effective. Consistent with its growth-promoting effect, glycine supplementation stimulated (p < 0.05) the phosphorylation of mechanistic target of rapamycin (MTOR), eukaryotic initiation factor 4E binding protein 1 (4E-BP1), and ribosomal protein S6 kinase beta-1 (p70^S6K) as well as protein synthesis in skeletal muscle, compared with the control group. Collectively, oral administration of glycine activated the MTOR signaling pathway in skeletal muscle and enhanced the growth performance of IUGR piglets. These results indicate that endogenous synthesis of glycine is inadequate to meet the needs of IUGR piglets during the suckling period and that oral supplementation with glycine to these compromized neonates can improve their growth performance. Full article

The ubiquitin-proteasome pathway performs a strictly controlled degradation of specific protein substrates within the eukaryotic cell. This catabolic mechanism allows the rapid removal of proteins damaged in any way, and therefore potentially capable of compromising cellular homeostasis, as well as the constant turnover of all cellular proteins, in order to balance their synthesis and thus maintain the correct levels of proteins required by the cell at any given time. Consequently, the ubiquitin-proteasome system plays a fundamental role in regulating essential cellular processes, such as the cell cycle, apoptosis, immune responses, and inflammation, whose dysregulation or malfunction can lead to neoplastic transformation. Not surprisingly, therefore, alterations in the activity and regulatory mechanisms of the proteasome are common not only in various types of tumors, but often represent a contributing cause of oncogenesis itself. Among proteasome modulators, PA28γ, due to its function in promoting cell growth and proliferation, while inhibiting apoptosis and cell-mediated immune responses, has received great attention in recent years for its well established pro-tumoral activity. Conversely, the role played in oncogenesis by the second paralogue of the PA28 family of proteasome activators, namely PA28αβ, is less clearly defined, which is also related to the lower level of general understanding of its cellular activities and biological functions. However, increasing experimental evidence has demonstrated that PA28αβ also plays a non-secondary role in the process of neoplastic transformation and tumor growth, both by virtue of its regulatory function on class I cell-mediated immune responses and through activity promoting cell duplication and growth. This review aims to summarize the current knowledge and evidence on the molecular mechanisms and cellular functions through which PA28αβ may support development and growth of cancer. Full article

Translational control is crucial for maintaining cellular homeostasis, yet the distinct features and regulatory requirements governing protein synthesis during erythropoiesis remain unclear. Here, we reveal that erythroid cells exhibit an extraordinarily high demand for protein synthesis, which is required for their differentiation but also implies the need for tight regulation to prevent excessive erythropoiesis. Notably, we identify significant phosphorylation of eukaryotic elongation factor 2 (eEF2) at threonine 56 during erythroid differentiation, which reduces protein synthesis and acts as a molecular brake to limit unchecked erythropoiesis. This is evidenced by elevated red blood cell counts in peripheral blood and increased incidence of blood hyperviscosity and thrombosis in eEF2_T56M mice, which are deficient in eEF2 phosphorylation. Mechanistic studies demonstrate that eEF2 phosphorylation selectively regulates the translation of a subset of proteins, including NFE2, which partially mediates the effects of eEF2 modification. Collectively, our findings highlight a previously unappreciated role for translational control in achieving efficient and balanced erythropoiesis, with eEF2 phosphorylation serving as a critical protective mechanism against hyperactive erythropoiesis and offering a potential therapeutic target for hematologic disorders such as polycythemia vera. Full article

5-methylcytosine (5mC) is a common form of DNA methylation, essentially acting as an epigenetic modification that regulates gene expression by affecting the binding of transcription factors to DNA or by recruiting proteins that make it difficult to recognize and transcribe genes. 5mC methylation is present in eukaryotes in a variety of places, such as in CpG islands, within gene bodies, and in regions of repetitive sequences, whereas in prokaryotic organisms, it is mainly present in genomic DNA. The Hippo pathway is a highly conserved signal transduction pathway, which is extremely important in cell proliferation and death, controlling the size of tissues and organs and regulating cell differentiation, in addition to its important regulatory roles in lipid synthesis, transport, and catabolism. Lipid metabolism is an important part of various metabolic pathways in the human body, and problems in lipid metabolism are related to abnormalities in key enzymes, related proteins, epigenetic inheritance, and certain specific amino acids, which are the key factors affecting its proper regulation. In this article, we will introduce the molecular mechanisms of 5mC methylation and the Hippo signaling pathway, and the possibility of their co-regulation of lipid metabolism, with the aim of providing new ideas for further research and novel therapeutic modalities for lipid metabolism and a reference for the development and exploration of related research. Full article

Gene expression is a complex process regulated at multiple levels in eukaryotic cells. Translation frequently represents a pivotal step in the control of gene expression. Among the stages of translation, initiation is particularly important, as it governs ribosome recruitment and the efficiency of protein synthesis. The 5′ untranslated region (5′ UTR) of mRNA plays a key role in this process, often exhibiting a complicated and structured landscape. Numerous eukaryotic mRNAs possess long 5′ UTRs that contain diverse regulatory elements, including RNA secondary structures, specific nucleotide motifs, and chemical modifications. These structural features can independently modulate translation through their intrinsic properties or by serving as platforms for trans-acting factors such as RNA-binding proteins. The dynamic nature of 5′ UTR elements allows cells to fine-tune translation in response to environmental and cellular signals. Understanding these mechanisms is not only fundamental to molecular biology but also holds significant biomedical potential. Insights into 5′ UTR-mediated regulation could drive advancements in synthetic biology and mRNA-based targeted therapies. This review outlines the current knowledge of the structural elements of the 5′ UTR, the interplay between them, and their combined functional impact on translation. Full article

Under conditions of amino acid deficiency, mammalian cells activate a nutrient-sensing kinase known as general control nonderepressible 2 (GCN2). The activation of GCN2 results in the phosphorylation of the alpha subunit of the eukaryotic initiation factor 2 (eIF2α), which can be phosphorylated by three other three integrated stress response (ISR) kinases, reducing overall protein synthesis. GCN2 activation also promotes the translation of specific mRNAs, some of which encode transcription factors that enhance the transcription of genes involved in the synthesis, transport, and metabolism of amino acids to restore cellular homeostasis. The phosphorylation of eIF2α has been shown to protect oligodendrocytes, the cells responsible for producing myelin in the central nervous system during remyelination. Here, we explore the potential role of the kinase GCN2 in the myelination process. We challenged mice deficient in the GCN2-encoding gene with a pharmacological demyelinating stimulus (cuprizone) and evaluated the recovery of myelin as well as ISR activation through the levels of eIF2α phosphorylation. Our findings indicate that GCN2 controls the establishment of myelin by fine-tuning its abundance and morphology in the central nervous system. We also found that GCN2 is essential for remyelination. Surprisingly, we discovered that GCN2 is necessary to maintain eIF2α levels during remyelination. Full article

In recent times, microalgae have emerged as powerful hosts for biotechnological applications, ranging from the production of lipids and specialized metabolites (SMs) of pharmaceutical interest to biofuels, nutraceutical supplements, and more. SM synthesis through bioengineered pathways relies on the availability of aromatic amino acids (AAAs) as an essential precursor. AAAs, phenylalanine, tyrosine, and tryptophan are also the building blocks of proteins, maintaining the structural and functional integrity of cells. Hence, they are crucial intermediates linking the primary and specialized metabolism. The biosynthesis pathway of AAAs in microbes and plants has been studied for decades, but not much is known about microalgae. The allosteric control present in this pathway has been targeted for metabolic engineering in microbes. This review focuses on the biosynthesis of AAAs in eukaryotic microalgae and engineering techniques for enhanced production. All the putative genes involved in AAA pathways in the model microalgae Chlamydomonas reinhardtii and Phaeodactylum tricornutum are listed in this review. Full article

Antibodies are complex protein structures, and producing them using eukaryotic expression systems presents significant challenges. One frequently overlooked aspect of expression vectors is the nucleotide sequence encoding the signal peptide, which plays a pivotal role in facilitating the secretion of recombinant proteins. This study presents the development of an integrative vector, pVEAL3, for expressing full-length recombinant monoclonal antibodies in mammalian cells. The vector features a distinctive nucleotide sequence that encodes an artificial chimeric signal peptide with the following amino acid sequence: MMRTLILAVLLVYFCATVHC. Additionally, the vector incorporates several regulatory elements to enhance antibody expression, including the Gaussia luciferase signal sequence, internal ribosome entry site (IRES), P2A peptide, and a furin cleavage site. These elements coordinate to regulate the synthesis levels of the antibody chains. The analysis of clones obtained via transfection with the developed vector showed that over 95% of them secreted antibodies at levels significantly higher than those of the control. The immunochemical analysis of the chimeric antibody produced by the CHO-K1-10H10ch cell line confirmed the preservation of its functional activity. Full article

The eukaryotic ribosome is a large ribonucleoprotein complex consisting of four types of ribosomal RNA (rRNA) and approximately 80 ribosomal proteins (RPs), forming the 40S and 60S subunits. In all living cells, its primary function is to produce proteins by converting messenger RNA (mRNA) into polypeptides. In addition to their canonical role in protein synthesis, RPs are crucial in controlling vital cellular processes such as cell cycle progression, cellular proliferation, differentiation, DNA damage repair, genome structure maintenance, and the cellular stress response. Viruses, as obligate intracellular parasites, depend completely on the machinery of the host cell for their replication and survival. During viral infection, RPs have been demonstrated to perform a variety of extra-ribosomal activities, which are especially important in viral disease processes. These functions cover a wide range of activities, ranging from controlling inflammatory responses and antiviral immunity to promoting viral replication and increasing viral pathogenicity. Deciphering the regulatory mechanisms used by RPs in response to viral infections has greatly expanded our understanding of their functions outside of the ribosome. Furthermore, these findings highlight the promising role of RPs as targets for the advancement of antiviral therapies and the development of novel antiviral approaches. This review comprehensively examines the many functions of RPs outside of the ribosome during viral infections and provides a foundation for future research on the host–virus interaction. Full article

Phenylalanine (Phe) is a potentially limiting amino acid for lactating cows. The mechanism by which Phe regulates milk protein synthesis remains unclear. The present study elucidates the mechanisms by which phenylalanine affects milk protein synthesis, amino acid utilization, and related signaling pathways in bovine mammary epithelial cells (BMECs). The BMECs were treated with five concentrations (0, 0.22, 0.44, 0.88, 1.76 mM, and serum free). Rapamycin inhibitors and RNA interference (RNAi) were used to inhibit the phosphorylation of the mammalian target of rapamycin (mTOR) signaling pathway and the expression of relevant amino acid transporters, respectively. The results showed that 4×Phe (0.88 mM) significantly increased (p < 0.05) both the mRNA and protein expression of α-casein (CSN1S1), β-casein (CSN2), and κ-casein (CSN3), as well as L-type amino acid transporter-1 (LAT1) mRNA expression. Protein expression and modification assays of mTOR-related proteins showed that 4×Phe could increase (p < 0.05) the expression of α-casein and eukaryotic initiation factor 4E-binding protein-1 (4EBP1) and tended to increase the expression of ribosomal protein S6 protein kinase (S6K1, p = 0.054). The general control nonderepressible 2 (GCN2) signaling pathway factor, eukaryotic initiation factor 2 (eIF2α), was downregulated by 4×Phe treatment (p < 0.05). The rapamycin inhibition test showed that Phe regulated casein synthesis via the mTOR signaling pathway. RNAi experiments showed that LAT1 mediated the entry of Phe into cells. Moreover, 4×Phe treatment tended to decrease (0.05 < p < 0.10) the consumption of valine, leucine, histidine, tyrosine, cysteine, alanine, asparagine, and serine in the medium. Collectively, phenylalanine enhanced α-casein synthesis by regulating the phosphorylation of 4EBP1 and eIF2α and promoting the formation of the mTOR-centered casein translation initiation complex. Full article

Background: General control nonderepressible 5 (Gcn5) is a lysine acetyltransferase (KAT) that is evolutionarily conserved across eukaryotes, with two homologs (Kat2a and Kat2b) identified in humans and one (Gcn5) in Drosophila. Gcn5 contains a P300/CBP-associated factor (PCAF) domain, a Gcn5-N-acetyltransferase (GNAT) domain, and a Bromodomain, allowing it to regulate gene expression through the acetylation of both histone and non-histone proteins. In Drosophila, Gcn5 is crucial for embryonic development, with maternal Gcn5 supporting early development. However, the functional mechanisms of Gcn5 after the depletion of maternal deposits remain unclear. Methods: Our study employed the Gal4/UAS-RNAi system to achieve whole-body or heart-specific Gcn5 knockdown in Drosophila and selected 96-hour-old surviving larvae for transcriptomic and metabolomic analyses. Results: Omics results revealed that Gcn5 knockdown significantly impacts various metabolic pathways, as well as lysosomes, non-homologous end-joining, Toll and Imd signaling pathways, and circadian rhythms, among others. Furthermore, defects in chitin synthesis may be associated with impaired pupation. Additionally, heart-specific Gcn5 knockdown affected cardiac physiology but appeared to have a potential protective effect against age-related cardiac decline. Conclusions: These findings deepen our understanding of Gcn5’s roles in Drosophila development and provide valuable insights for developing Gcn5-targeted therapies, particularly considering its involvement in various human diseases. Full article

In the eukaryotic cells, the ubiquitin–proteasome system (UPS) plays a crucial role in the intracellular protein turnover. It is involved in several cellular functions such as the control of the regular cell cycle progression, the immune surveillance, and the homeostasis. Within the 20S proteasome barrel-like structure, the catalytic subunits, β1, β2 and β5, are responsible for different proteolytic activities: caspase-like (C-L), trypsin-like (T-L) and chymotrypsin-like (ChT-L), respectively. The β5 subunit is particularly targeted for its role in antitumor activity: the synthesis of β5 subunit inhibitors could be a promising strategy for the treatment of solid and hematologic tumors. In the present work, we performed two combination studies of AM12, a recently developed synthetic proteasome inhibitor, with curcumin and quercetin, two nutraceuticals endowed of many pharmacological properties. We measured the combination index (CI), applying the Chou and Talalay method, comparing the two studies, from 50% to 90% of proteasome inhibition. In the case of the combination AM12 + curcumin, an increasing synergism was observed from 50% to 90% of proteasome inhibition, while in the case of the combination AM12 + quercetin an additive effect was observed only from 50% to 70% of β5 subunit inhibition. These results suggest that combining AM12 with curcumin is a more promising strategy than combining it with quercetin for potential therapeutic applications, especially in treating tumors. Full article