Rong Liu

The decay of smooth muscle contractility is a major trigger of aging-related intestinal hypomotility, which imposes a substantial healthcare burden. Despite this, effective targeted therapy for this condition remains unavailable. Here, we identified the probiotic Bifidobacterium animalis subsp. lactis BL-99 as a microbiota modulator that restores gut motility through the bile acid (BA)-mediated rescue of smooth muscle contractile function. In a randomized, double-blind clinical trial (ChiCTR2300077583, with the primary endpoint of whole-gut transit time [WGTT], and secondary endpoints including bowel movement frequency, symptom severity, and quality-of-life measures) and naturally aged mouse models, BL-99 intervention significantly reduced the WGTT and concurrently remodeled the gut microbiota. This suppressed bile salt hydrolase-expressing bacteria, which preserved conjugated BA pools, including taurochenodeoxycholic acid (TCDCA). Mechanistic investigations revealed that BL-99 was associated with enhanced expression of the serum response factor (SRF)–myocardin (Myocd) transcriptional axis in colonic smooth muscle cells (SMCs), restoring contractile apparatus components (e.g., α-SMA, SM-MHC). Crucially, TCDCA administration recapitulated BL-99 regulation of intestinal SMC contractile protein expression by inhibiting the PI3K/AKT pathway. Our findings established a microbiota-BA-SMC signaling axis that ameliorates age-related intestinal hypomotility, positioning both BL-99 and TCDCA as precision therapeutic candidates targeting SMC-related dysmotility.

Peptides derived from animal proteins have attracted increasing attention as natural inhibitors of dipeptidyl peptidase-IV(DPP-Ⅳ) for the management of type 2 diabetes mellitus (T2DM). Here, we compared the anti-diabetic potential of fish collagen peptides (FCP), casein peptides (CP), and ovalbumin peptides (OP). Among them, FCP showed the strongest hypoglycemic effect, significantly improving insulin sensitivity and tissue damage in the liver and pancreas of type 2 diabetic mice. LC–MS characterization and molecular docking identified GPLGPR as the most active peptide within FCP. GPLGPR bound tightly to the DPP-Ⅳ catalytic pocket through hydrogen bonding with Glu205 and Glu206 and hydrophobic interactions with Phe357, Tyr547, and Trp629, consistent with a competitive inhibition mode. In vivo, GPLGPR suppressed DPP-Ⅳ activity, elevated serum GLP-1 levels, and reduced hepatic gluconeogenic gene expression, thereby improving glucose metabolism and alleviating diabetic symptoms such as weight loss, polydipsia, and tissue injury. Collectively, these findings identify GPLGPR as a potent natural DPP-Ⅳ inhibitory peptide with strong potential for dietary intervention in T2DM.

Metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH) are two common liver disorders characterized by abnormal lipid accumulation. Our study found reduced levels of GTPase-activating protein-binding protein1 (G3BP1) in patients with MASLD and MASH, suggesting its involvement in these liver disorders. Hepatocyte-specific G3BP1 knockout (G3BP1 HKO) male mice had more severe MASLD and MASH than their corresponding controls. Intriguingly, the G3BP1 HKO MASLD model male mice exhibit dysregulated autophagy, and biochemical analyses demonstrated that G3BP1 promotes autophagosome-lysosome fusion through direct interactions with the SNARE proteins STX17 and VAMP8. We also show that hepatic knockout of G3BP1 promotes de novo lipogenesis, and ultimately found that G3BP1 is required for the nuclear translocation of the well-known liver-lipid-regulating transcription factor TFE3. Taken together, our results suggest that G3BP1 should be investigated as a potential target for developing medical interventions to treat MASLD and MASH.

Background: The milk fat globule membrane (MFGM) is a thin film that exists within the milk emulsion, suspended on the surface of milk fat globules, and comprises a diverse array of bioactive components. Recent advancements in MFGM research have sparked a growing interest in its biological characteristics and health-related functions. Thorough exploration and utilization of MFGM as a significant bioactive constituent in milk emulsion can profoundly impact human health in a positive manner. Scope and approach: This review comprehensively examines the current progress in understanding the structure, composition, physicochemical properties, methods of separation and purification, and biological activity of MFGM. Additionally, it underscores the vast potential of MFGM in the development of additives and drug delivery systems, with a particular focus on harnessing the surface activity and stability of proteins and phospholipids present on the MFGM for the production of natural emulsifiers and drug encapsulation materials. Key findings and conclusions: MFGM harbors numerous active substances that possess diverse physiological functions, including the promotion of digestion, maintenance of the intestinal mucosal barrier, and facilitation of nerve development. Typically employed as a dietary supplement in infant formula, MFGM’s exceptional surface activity has propelled its advancement toward becoming a natural emulsifier or encapsulation material. This surface activity is primarily derived from the amphiphilicity of polar lipids and the stability exhibited by highly glycosylated proteins.

Current treatment for functional dyspepsia (FD) has limited and unsustainable efficacy. Probiotics have the sustainable potential to alleviate FD. This randomized controlled clinical trial (Chinese Clinical Trial Registry, ChiCTR2000041430) assigned 200 FD patients to receive placebo, positive-drug (rabeprazole), or Bifidobacterium animalis subsp. lactis BL-99 (BL-99; low, high doses) for 8-week. The primary outcome was the clinical response rate (CRR) of FD score after 8-week treatment. The secondary outcomes were CRR of FD score at other periods, and PDS, EPS, serum indicators, fecal microbiota and metabolites. The CRR in FD score for the BL-99_high group [45 (90.0%)] was significantly higher than that for placebo [29 (58.0%), p = 0.001], BL-99_low [37 (74.0%), p = 0.044] and positive_control [35 (70.0%), p = 0.017] groups after 8-week treatment. This effect was sustained until 2-week after treatment but disappeared 8-week after treatment. Further metagenomic and metabolomics revealed that BL-99 promoted the accumulation of SCFA-producing microbiota and the increase of SCFA levels in stool and serum, which may account for the increase of serum gastrin level. This study supports the potential use of BL-99 for the treatment of FD.

SCFD1 (sec1 family domain containing 1) was recently shown to function in autophagosome-lysosome fusion, and multiple studies have demonstrated the regulatory impacts of acetylation (a post-translational modification) on macroautophagy/autophagy. Here, we demonstrate that both acetylation- and phosphorylation-dependent mechanisms control SCFD1ʹs function in autophagosome-lysosome fusion. After detecting a decrease in the extent of SCFD1 acetylation under autophagy-stimulated conditions, we found that KAT2B/PCAF catalyzes the acetylation of residues K126 and K515 of SCFD1; we also showed that these two residues are deacetylated by SIRT4. Importantly, we showed that AMPK-controlled SCFD1 phosphorylation strongly disrupts the capacity of SCFD1 to interact with KAT2B, thus ensuring that the SCFD1 acetylation level remains low. Finally, we demonstrated that SCFD1 acetylation inhibits autophagic flux, specifically by blocking STX17-SNAP29-VAMP8 SNARE complex formation. Thus, our study reveals a mechanism through which phosphorylation and acetylation modifications of SCFD1 mediate SNARE complex formation to regulate autophagosome maturation.ACLY: ATP citrate lyase; CREB: cAMP responsive element binding protein; EBSS: nutrient-deprivation medium; EP300: E1A binding protein p300; KAT5/TIP60: lysine acetyltransferase 5; HOPS: homotypic fusion and protein sorting; MS: mass spectroscopy; SCFD1: sec1 family domain containing 1; SM: Sec1/Munc18; SNARE: soluble N-ethylmaleimide-sensitive factor attachment protein receptor; UVRAG: UV radiation resistance associated