PubMed · 15399601
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E KATCHALSKI, P SPITNIK. 1949-12-24. Poly-arginine.. https://doi.org/10.1038/1641092a0
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Insomnia is associated with gut microbial dysbiosis, but the specific microbial metabolites mediating gut-brain communication remain elusive. Here, we integrate metagenomic sequencing from 171 individuals (primary insomnia, post-COVID insomnia, and controls) with functional pathway analysis and preclinical validation. We identify Faecalibacterium prausnitzii depletion and reduced L-arginine biosynthesis as consistent features in both insomnia subtypes, accompanied by elevated cortisol levels. Genomic and in vitro analyses confirm that F. prausnitzii is a key microbial contributor to L-arginine production. In a chronic mild stress mouse model, administration of either F. prausnitzii or L-arginine restores sleep duration, normalizes corticosterone levels, and reverses stress-induced gut dysbiosis. Mechanistically, L-arginine suppresses POMC gene expression and dampens adrenocorticotropic hormone (ACTH)-stimulated corticosterone release, implicating the POMC-ACTH-cortisol axis as a key target. These findings uncover a gut-brain axis driven by F. prausnitzii-derived L-arginine that modulates sleep through endocrine signaling, positioning this metabolite as a potential therapeutic avenue for insomnia.
OBJECTIVE: This meta-analysis aimed to evaluate the effect of oral l-arginine supplementation on ambulatory blood pressure (ABP). METHODS: A systematic search of PubMed, Cochrane Library, Embase, and Web of Science databases was conducted from their inception through March 1, 2026. Randomized controlled trials (RCTs) assessing the effects of oral l-arginine intervention were included. Outcome measures included 24-h systolic blood pressure (24h SBP), 24-h diastolic blood pressure (24h DBP), daytime systolic blood pressure (dSBP), daytime diastolic blood pressure (dDBP), nighttime systolic blood pressure (nSBP), and nighttime diastolic blood pressure (nDBP). Meta-analysis was performed using Stata 17.0. The weighted mean difference (WMD) was used as the effect size, and the results were pooled with 95% confidence intervals (CIs). RESULTS: A total of 5 RCTs comprising 202 participants were included. Meta-analysis results demonstrated that oral l-arginine significantly reduced 24h SBP (WMD = -4.23 mmHg, 95% CI [-5.87, -2.58]; P < 0.01) and 24h DBP (WMD = -3.04 mmHg, 95% CI [-4.48, -1.59]; P < 0.01). Significant reductions were also observed for dSBP (WMD = -4.16 mmHg, 95% CI [-5.90, -2.41]; P < 0.01) and dDBP (WMD = -4.25 mmHg, 95% CI [-5.85, -2.66]; P < 0.01). Furthermore, oral l-arginine significantly lowered nSBP (WMD = -5.70 mmHg, 95% CI [-7.81, -3.58]; P < 0.01) and nDBP (WMD = -4.18 mmHg, 95% CI [-6.27, -2.09]; P < 0.01). CONCLUSION: Oral l-arginine supplementation significantly reduces ABP. However, the number of included studies was limited, and further validation through additional relevant research is warranted.
The twin arginine (Tat) secretion pathway allows the translocation of folded proteins across the cytoplasmic membrane of bacteria. Tat-specific signal peptides contain a characteristic amino acid motif ((S/T)RRXFLK) including two highly conserved consecutive arginine residues that are thought to be involved in the recognition of the signal peptides by the Tat translocase. Here, we have analyzed the specificity of Tat signal peptide recognition by using a genetic approach. Replacement of the two arginine residues in a Tat-specific precursor protein by lysine-glutamine resulted in an export-defective mutant precursor that was no longer accepted by the wild-type translocase. Selection for restored export allowed for the isolation of Tat translocases possessing single mutations in either the amino-terminal domain of TatB or the first cytosolic domain of TatC. The mutant Tat translocases still efficiently accepted the unaltered precursor protein, indicating that the substrate specificity of the translocases was not strictly changed; rather, the translocases showed an increased tolerance toward variations of the amino acids occupying the positions of the twin arginine residues in the consensus motif of a Tat signal peptide.