Amino Acids最新文献

ABCA1 is a key protein in maintaining cholesterol homeostasis, and its abnormal expression is associated with the progression of many cancers. Nonetheless, the specific molecular mechanisms by which ABCA1 facilitates the development of LUAD remain largely unexplored, necessitating further in-depth investigation. The TCGA-LUAD database was used to analyze the expression of ABCA1 in LUAD tissues. Subsequently, a cell model with overexpressed ABCA1 was constructed for verification through cell experiments. Cell function was evaluated using the Transwell assay and the colony formation assay. Intracellular cholesterol levels were detected using a kit. At the same time, the online database RM2 Target was employed to predict upstream factors that may have a methylation regulatory relationship with ABCA1. On this basis, Dot blot and MeRIP-qPCR techniques were employed to determine the degree of m6A modification. To clarify the mechanism of IGF2BP1 regulating ABCA1 through the m6A pathway, RNA pull-down binding experiments were carried out, and changes in mRNA stability were assessed using actinomycin D treatment. Finally, the biological function of the IGF2BP1/ABCA1 signaling axis during the growth and metastasis of LUAD in vivo was evaluated by establishing a xenograft animal model. Bioinformatics analysis and cell experimental results confirmed the low expression of ABCA1 in LUAD tissues and cells. ABCA1 significantly inhibited cell proliferation, migration, and invasion capabilities, promoted apoptosis, and reduced intracellular cholesterol levels. From a molecular perspective, IGF2BP1 recognized and bound to methylation sites on ABCA1 mRNA, thereby accelerating its degradation process, resulting in a substantial decrease in the stability of ABCA1 mRNA. Moreover, in vivo and in vitro experiments further confirmed that IGF2BP1 affected cholesterol metabolism by regulating the expression of ABCA1, thereby facilitating the malignant progression of LUAD. Overall, our research revealed that IGF2BP1 affects cholesterol metabolism by reducing the stability of ABCA1 mRNA through m6A modification, thereby boosting the malignant progression of LUAD and formulating a theoretical basis for subsequent LUAD treatment.

β-Aminodehydroalanine, ΔAla(β-NH), (2,3-diaminoprop-2-enoic acid), is a unique dehydroamino acid and a central component of Callyaerins A-M and Callynormine A. The presence of this unusual structural element containing an enamine functional group may be related to the antitubercular activity of Callyaerins. According to The WHO Global Tuberculosis Report tuberculosis is the second leading cause of death worldwide caused by a single infectious agent. Therefore, it is essential to understand the molecular structure of these peptides in more detail. To investigate the conformational properties of the ΔAla(β-NH) residue, a series of model compounds: Ac-(Z/E)-ΔAla(β-NHMe)-NHMe, Ac-(Z/E)-ΔAla(β-NHMe)-NMe₂, Boc-Gly-(Z)-ΔAla(β-NHMe)-OMe, and Boc-Gly-(Z)-ΔAla(β-Leu-OMe)-OMe, were selected for quantum chemical calculations and/or synthesized. Two conformations, β2 (φ,ψ ~ − 120°, 20°) and α (φ,ψ ~ − 70°, − 15°) are predicted as the most preferable, regardless of the geometry of isomer (Z/E), polarity of environment, and order (2°/3°) of C-terminal amide group. The N–H⋯O hydrogen bond involving the N–H group in the β position of the side chain as a donor is a significant stabilizing factor. The Z isomer is predicted to be the most stable and has been synthesized. The following synthesis method is proposed: Ser → ΔAla → ΔAla(β-Br) → ΔAla(β-NH). The advantages of the proposed method are: (i) serine as the starting substrate, (ii) mild alkaline conditions, (iii) avoidance of the reactive intermediate α-formylglycine.

Ezrin is a crucial structural protein that connects the plasma membrane to the actin cytoskeleton to maintain cell shape, adhesion, and motility. Post-translational modifications (PTMs) play a key role in the regulation of various biological functions and have been implicated in a range of pathological conditions. With the help of PTMs, ezrin not only plays a structural role in connecting the cell membrane to F-actin, but also participates in transmitting cellular signals including those related to inflammatory responses. In this study, we reviewed the key sites and domains involved in the different PTMs of ezrin, including acetylation, lactylation and phosphorylation. We analyzed the regulation of biological processes mediated by different PTMs of ezrin, such as cell migration, inflammation regulation and cell stiffness. In addition, we examined the mutual regulatory effects of different modifications of ezrin, including regulation of ezrin phosphorylation by kinases and phosphatases, and so on. Increasing evidence suggests that PTMs of ezrin are involved in cancer, respiratory diseases and urological diseases. These studies provide novel insights into the design of new disease treatment strategies targeting ezrin.

L-arginine (L-Arg) is metabolised in the cell to generate nitric oxide (NO) and citrulline via nitric oxide synthase (NOS). NO is an important cellular signalling molecule that regulates lipid and glucose metabolism. The biological availability of NO is affected by the NOS inhibitor; N^G-nitro-L-Arg methyl ester (L-NAME) and the external NO donor; S-nitroso-N-acetyl-D, L-penicillamine (SNAP). Mouse adipocyte 3T3 L1 cells were cultured with 0, 400 and 800 µM L-Arg or control complete DMEM media. The impact of L-NAME (4 mM), and SNAP (100 µM) was also analysed. The cell fitness was similar and the mRNA levels of AMPK was increased and ACC-1 was decreased, whilst the activation of AMPK and ACC-1 was decreased upon the addition of exogenous L-Arg. Transcript and protein levels of AMPK and ACC-1 were regulated by addition of L-NAME and SNAP, however the impact of these targets was related to the concentration of L-Arg added to the cells and the culture time point of analysis. NO in the form of NO₂⁻ in cell culture supernatant was elevated in 400 and 800 µM L-Arg cultures. L-NAME significantly inhibited NO production from adipose cells in a time-dependent manner and subsequently impacted AMPK and ACC expression. Associated with these changes were changed in the concentration of L-Arg, L-Cit and L-Orn in the culture media. Collectively, these results show that excess L-Arg is sensed by the cell which then regulates AMPK and ACC-1 expression in response. The findings could have implications in modulation of signalling pathways for treating obesity and obesity induced diabetic mellitus.

Background

Oxidative stress is a key contributor to the progression of diabetes mellitus and its associated complications. Recently, S-adenosyl methionine (SAM) has shown promise in mitigating oxidative stress and improving glucose metabolism. This study aimed to investigate the effects of SAM supplementation on biochemical parameters, oxidative stress markers, and histopathological alterations in the kidneys and liver of streptozotocin (STZ)-induced diabetic rats.

Methods

Eighteen male Wistar rats were randomly divided into three groups (n = 6 per group): non-diabetic control, diabetic control, and diabetic rats treated with SAM (10 mg/kg/day, intraperitoneally) for 4 weeks. Fasting blood glucose, renal and hepatic biochemical markers (urea, creatinine, ALT, AST), and oxidative stress markers (malondialdehyde, protein carbonyls, total antioxidant capacity) were measured. Histopathological changes in kidney and liver tissues were also assessed.

Results

Diabetic rats treated with SAM exhibited minor, non-significant changes in fasting blood glucose, urea, creatinine, ALT, and AST levels. In contrast, treatment with SAM in diabetic rats significantly reduced malondialdehyde and protein carbonyl levels in both kidney and liver tissues compared to the diabetic control group (P < 0.05). Furthermore, histopathological analysis revealed improved tissue architecture and reduced pathological changes in the diabetic group treated with SAM.

Conclusion

Our findings demonstrated that SAM supplementation exerts significant antioxidant and histopathological protective effects against diabetes-induced damage in kidney and liver tissues.

Previously, we have shown that CacyBP/SIP interacts with NPM1, a protein involved in ribosome biogenesis. In this work, we extended our previous studies to look for the potential impact of CacyBP/SIP on ribosome biogenesis and/or function. Using mass spectrometry analysis, we have found that several RPs could be potential CacyBP/SIP targets. Since RPL6 was one of the proteins with the best quality scores identified in this analysis we focused on the possible interaction between CacyBP/SIP and RPL6. By applying various biochemical methods, we confirmed this interaction and showed that it was direct. Moreover, in silico analysis allowed us to establish the domains/fragments of both proteins involved in the binding. To further explore the possible role of CacyBP/SIP in ribosome function we performed several analyses using neuroblastoma NB2a cell line with stably silenced CacyBP/SIP expression. We have found, by applying OPP (O-propargyl-puromycin), which labels nascent polypeptides, that the number of cells with enhanced staining in the perinuclear area, reminiscent of rough ER localization, was significantly lower in the cell line with diminished CacyBP/SIP level. To verify the influence of CacyBP/SIP on the efficiency of protein synthesis we investigated the level of Hsp70, a stress-inducible protein, in NB2a cells subjected to heat shock. The results, showing markedly higher Hsp70 production in control cells, indicate that CacyBP/SIP, most probably through interaction with RPL6 and/or other RPs, may have some influence on ribosome function and, possibly, on protein synthesis in the cell.

The biotransformation of L-glutamic acid (L-Glu) to γ-aminobutyric acid (GABA) using glutamate decarboxylase (GAD) in microbial whole cells represents an ideal approach for biosynthesis of food-grade and pharmaceutical-grade GABA. To overcome the cell membrane barrier, enhance mass transfer efficiency in the whole-cell reaction system, and improve GABA biosynthesis efficiency, we established a novel ethanol-enhanced whole-cell biocatalytic co-reaction system through systematic investigations on the enzymatic characteristics of GAD in Pediococcus pentosaceus whole cells and the regulatory effects mediated by ethanol. The results showed that the optimal reaction pH and temperature for GAD in P. pentosaceus whole cells were 4.2 and 32 °C, respectively. A 7.5% (v/v) ethanol concentration significantly promoted the activity of whole-cell GAD, but reduced its stability. Through orthogonal test optimization, the optimal reaction conditions for ethanol-promoted GABA synthesis via P. pentosaceus whole-cell transformation were as follows: mixing 0.3 M monosodium glutamate (MSG) solution with 100 mg/ml cell suspension at a 1:1 volume ratio, adding 40 g/l of L-Glu/MSG (2:1) solid mixture, adjusting the final ethanol concentration to 3.75% (v/v), reacting at pH 4.2, 28 °C for 40 h. Under these conditions, the GABA yield reached 366.07 ± 5.57 mM, which was 21.44 ± 1.85% higher than that of the control group without ethanol. As an enhancer, ethanol demonstrates great application potential in GABA production via whole-cell transformation due to its high safety and ease of use.

Designing innovative, accurate, universal, and accessible diagnostic tests is mandatory to improve screening, prevention, and management of hepatitis D (HD), especially in endemic areas with poor infrastructure and restricted access to public health care. Recombinant proteins (RP), recombinant multiepitope proteins (RMP), and synthetic peptides have been extensively reported as tools for efficient immunodiagnosis of several diseases. This review aimed to discuss the use of these antigens for the immunodiagnosis of HD. To this end, a bibliographic study was conducted in the PubMed database by searching the primary (“Hepatitis D” and “Hepatitis Delta”), secondary (“Detection”, “Diagno*”, “Diagnosis”, “Immunodiagnosis”, and “Serodiagnosis”), and tertiary (“Chimera”, “Epitope”, “Peptide”; “Protein” and “Recombinant”) descriptors, including papers published up to January 2025. Review articles and case reports were excluded. Only nine articles (five for RP, three for synthetic peptides, and one for RMP) met the inclusion criteria, revealing that there are very few studies on this subject, particularly when compared to the advances made in the diagnosis of hepatitis A, B, and C. Despite the scarcity of articles published in the literature, six of the nine analyzed studies corroborate the potential of these antigens to effectively replace traditional diagnostic methods, including development of rapid tests. These data highlight the need for further studies to assess the potential of RP, RMP, and synthetic peptides for immunodiagnosis of HD, aiming to increase the accuracy of diagnosis, as well as improve monitoring and prevention.

The L-arginine derivative and uremic toxin symmetric dimethylarginine (SDMA) is an independent risk marker for total mortality and cardiovascular events. Interferences with L-arginine- or L-homoarginine-related signaling, metabolism, or transport have been proposed as underlying mechanisms. SDMA is endogenously formed and predominantly eliminated via the kidney. Whereas for L-arginine and other L-arginine derivatives such as L-homoarginine and asymmetric dimethylarginine (ADMA) key transport proteins involved in the cellular uptake and release have been characterized, comparable data for the transport of SDMA are lacking.

Using HEK cell lines overexpressing the transport proteins OCT2, OATP4C1, MATE1, OAT4, and OAT10, which are all expressed in renal proximal tubule cells, and the ubiquitously-expressed transport protein CAT1 we performed uptake experiments demonstrating that SDMA is a substrate for CAT1, OATP4C1, OCT2, and MATE1 in physiological concentrations, but not of OAT4 and OAT10. K_m values for OATP4C1-, CAT1-, and MATE1-mediated SDMA uptake were 70 µM, 246 µM, and 1 973 µM, respectively. For OCT2-mediated uptake, no saturation could be reached, precluding the determination of a K_m value. Uptake of SDMA by these transporters could be inhibited by known substrates of the respective transport proteins. Furthermore, CAT1 and OATP4C1 also mediate the efflux of SDMA out of cells.

These results show that SDMA is a substrate of renally-expressed transport proteins OATP4C1, OCT2, and MATE1 and of CAT1 demonstrating that these transporters are involved in the homeostasis of this uremic toxin and possible sites of interactions with related compounds.

Silk glands are modified labial glands that produce silk which has immense commercial importance. Silk is extruded out in liquid form after which the glands undergo autophagy and apoptosis during larval to pupal transition. Biogenic amines, specially spermidine and γ-aminobutyric acid (GABA) are known to play an important role in autophagy. Yet, GABA is not identified in the silk glands till now and therefore its role in autophagy remains unknown. Current study aimed to evaluate role of biogenic amines in the autophagy of silk glands. Fifth instar silkworms were fed with control and spermidine supplemented mulberry leaves under controlled conditions. Qualitative and quantitative analysis of biogenic amines were analyzed in silk glands of control and spermidine fed groups at the end of feeding stage, spinning and pre-pupal stages. Biogenic amines were significantly decreased in the silk glands from feeding stage to non-feeding prepupal stages. Elevated levels of biogenic amines; putrescine, spermidine, and spermine were observed in silk glands at pre-pupal stage in the spermidine fed group. The unknown biogenic amine whose levels were significantly elevated during silk gland degeneration in both control and spermidine fed groups was identified as GABA by spectroscopic techniques. This is the first report of the identification of GABA in the silk glands of Bombyx mori which increased significantly following spermidine supplementation, resulting in elevated levels of calcium deposits, contributing to the early degeneration of the silk glands.