Manli Hu

BACKGROUND: Excessive unnecessary protein accumulation in cardiomyocyte is a leading contributor for pathological cardiac hypertrophy and has been found closely regulated by the mTORC1 (mechanistic target of rapamycin complex 1) signaling and lysosome transmembrane proteins. However, the precise regulatory mechanism stratifying mTORC1 signaling and the specific functions of lysosomal proteins in protein homeostasis of cardiomyocytes remain largely unidentified. METHODS: We screened lysosomal genes conserved in mice, rats, and humans. Adenoviral infection of rat cardiomyocytes was used to assess the functional role of LAPTM4A (lysosome-associated protein transmembrane 4A). To evaluate its effects in vivo, adeno-associated virus 9 driven by the cardiac troponin T promoter was used for cardiomyocyte-specific expression. RNA sequencing and mass spectrometry–based proteomics were performed to elucidate the underlying molecular mechanisms. Last, a dual-luciferase reporter assay was used to screen a Food and Drug Administration–approved drug library for compounds that suppress LAPTM4A expression. RESULTS: Lysosomal transmembrane proteins expressed in cardiomyocytes were screened for their roles in regulating hypertrophy, and LAPTM4A emerged as a potent promoter of cardiomyocyte hypertrophy and prohypertrophic gene expression. Overexpression of LAPTM4A aggravated cardiac remodeling and dysfunction by enhancing mTORC1-p70S6K (70-kDa ribosomal protein S6 kinase)/4EBP1 (eukaryotic translation initiation factor 4E-binding protein 1)–mediated protein synthesis, without affecting lysosomal autophagy, in a NEDD4L (neural precursor cell expressed developmentally downregulated 4–like)–dependent manner. Mechanistically, LAPTM4A directly interacted with NEDD4L, facilitating K63-linked ubiquitination of AKT (protein kinase B [v-akt murine thymoma viral oncogene homolog]) and subsequent activation of mTORC1 signaling. Cardiomyocyte-specific deletion of LAPTM4A significantly attenuated myocardial hypertrophy and fibrosis induced by transverse aortic constriction in mice. Furthermore, a dual-luciferase reporter screen identified magnolol, a Food and Drug Administration–approved compound, as a suppressor of LAPTM4A expression with marked cardioprotective effects in vivo. CONCLUSIONS: Our study identified a novel mTORC1 booster LAPTM4A and verified interrupting the LAPTM4A-mTORC1 axis can significantly inhibit excessive protein synthesis and pathological cardiac hypertrophy, which might represent an attractive therapeutic approach for this disease.

BACKGROUND: Myocardial ischemia-reperfusion (MIR) injury compromises therapeutic effects of revascularization and leads to functional impairment and exacerbation of structural damage in the heart. Limiting the damage caused by MIR is crucial but is still an unmet clinical need because of the complexity of the underlying mechanisms. Increasing evidence suggests that lysosomal autophagy plays a significant regulatory role in MIR injury. The specific mechanisms involved remain to be fully understood. METHODS: We here systematically analyzed the murine MIR model database to screen the potentially protective lysosome-localized proteins against MIR injury. The positive hits were further functionally screened and validated for their capability on autophagy and hypoxia/reoxygenation insults of cardiomyocytes. After exploring the detailed molecular mechanism underlying the protective effects of the target protein, we generated target gene cardiac-specific knockout mice and overexpression mice to verify its function in mouse MIR injury models. RESULTS: LAPTM4A (lysosome-associated protein transmembrane 4 alpha) stood out as a significant protective lysosome-localized protein from the screening. LAPTM4A deficiency significantly heightened the inflammatory response and cell death both in primary cardiomyocytes and in a MIR-induced mouse model. Conversely, LAPTM4A overexpression exerted protective effects on cell viability and myocardial damage. Mechanistically, LAPTM4A interacts with Rubicon (Run domain Beclin1-interacting and cysteine-rich domain–containing protein), hindering its engagement within the Beclin1 complex, resulting in a robust augmentation of autophagic flux and thereby mitigating cardiac damage during reperfusion. It is important to note that Rubicon knockdown markedly reversed the aggravated injury induced by LAPTM4A knockdown, further verifying the effects of LAPTM4A depend on Rubicon. CONCLUSIONS: Our findings screened out and validated that LAPTM4A is a lysosome-localized protein exerting protective effects against MIR injury by facilitating autophagic flux. Targeting LAPTM4A represents a promising therapeutic strategy for mitigating MIR injury.

Journal of Animal Science and Technology (JAST) is a peer-reviewed, open access journal publishing original research, review articles and notes in all fields of animal science. Topics covered by the journal include: genetics and breeding, physiology, nutrition of monogastric animals, nutrition of ruminants, animal products (milk, meat, eggs and their by-products) and their processing, grasslands and roughages, livestock environment, animal biotechnology, animal behavior and welfare.

Background: The purpose of our study was to study the composition and content of the feline plasma metabolome revealing the critical metabolites and metabolic pathways associated with age during growth and development.Methods: Blood samples were collected from juvenile and adult groups for blood routine tests and serum biochemistry tests. Non‐targeted metabolomics analyses of plasma were also performed to investigate changes in metabolites and metabolic pathways.Results: In this study, we found that the red blood cell counts, liver function indexes (albumin and gamma‐glutamyl transpeptidase), and the concentration of triglyceride and glucose changed significant with growth and development. The metabolomics results revealed that 1427 metabolites were identified in the plasma of young and adult cats. Most of these metabolites belong to major classes of lipids and lipid‐like molecules. The most obvious age‐related metabolites include reduced levels of chenodeoxycholate, taurocholate, cholate, and taurochenodeoxycholate but increased levels of L‐cysteine and taurocyamine in the adult cat's serum. These metabolites are mainly involved in the primary bile acid biosynthesis pathway, the bile secretion pathway, and the taurine and hypotaurine metabolism pathway.Conclusion: This study revealed many age‐related metabolite alterations in the feline plasma. These age‐varying metabolites, especially in the bile acid biosynthesis and secretion metabolism pathways, indicate that the regulation of these pathways is involved in the growth and development of cats. This study promotes our understanding of the mechanism of feline growth and provides new insights into nutrition and medicine for cats of different ages.

Background and Aims: NAFLD is a progressive disease without known effective drug treatments. Switch‐associated protein 70 (SWAP70) is a guanine nucleotide exchange factor that participates in the regulation of many cellular processes. However, the role of SWAP70 in NAFLD remains unclear. This study aimed to identify the function and mechanism of SWAP70 in NAFLD. Approach and Results: The results showed that the expression of SWAP70 was significantly increased in mice and hepatocytes after metabolic stimulation. Overexpression of SWAP70 in hepatocytes suppressed lipid deposition and inflammation, and SWAP70 knockdown created the inverse effect. Using hepatocyte‐specific Swap70 knockout and overexpression mice fed a high‐fat, high‐cholesterol diet, we demonstrated that SWAP70 suppressed the progression of nonalcoholic steatohepatitis by inhibiting lipid accumulation, inflammatory response, and fibrosis. Mechanically, RNA sequencing analysis and immunoprecipitation assays revealed that SWAP70 inhibited the interaction between transforming growth factor β‐activated kinase 1 (TAK1) binding protein 1 and TAK1 and sequentially suppressed the phosphorylation of TAK1 and subsequent c‐Jun N‐terminal kinase/P38 signaling. Inhibition of TAK1 activation blocked hepatocyte lipid deposition and inflammation caused by SWAP70 knockdown. Conclusions: SWAP70 is a protective molecule that can suppress the progression of NAFLD by inhibiting hepatic steatosis and inflammation. SWAP70 may be important for mitigating the progression of NAFLD.

IMA-1 targets the ALOX12-ACC1 interaction to both prevent and treat NASH without inducing hyperlipidemia.

ALOX12 drives NASH by inhibiting ACC1 lysosomal degradation across multiple species.

Measles is one of the most infectious diseases of humans. It is caused by the measles virus (MeV) and can lead to serious illness, lifelong complications, and even death. Whole‐genome sequencing (WGS) is now available to study molecular epidemiology and identify MeV transmission pathways. In the present study, WGS of 23 MeV strains of genotype H1, collected in Mainland China between 2006 and 2018, were generated and compared to 31 WGSs from the public domain to analyze genomic characteristics, evolutionary rates and date of emergence of H1 genotype. The noncoding region between M and F protein genes (M/F NCR) was the most variable region throughout the genome. Although the nucleotide substitution rate of H1 WGS was around 0.75 × 10⁻³ substitution per site per year, the M/F NCR had an evolutionary rate three times higher, with 2.44 × 10⁻³ substitution per site per year. Phylogenetic analysis identified three distinct genetic groups. The Time of the Most Recent Common Ancestor (TMRCA) of H1 genotype was estimated at approximately 1988, while the first genetic group appeared around 1995 followed by two other genetic groups in 1999–2002. Bayesian skyline plot showed that the genetic diversity of the H1 genotype remained stable even though the number of MeV cases decreased 50 times between 2014 (52 628) and 2020 (993). The current coronavirus disease 2019 (COVID‐19) pandemic might have some effect on the measles epidemic and further studies will be necessary to assess the genetic diversity of the H1 genotype in a post‐COVID area.

Background and Aims: NASH is becoming a leading cause of liver cirrhosis and HCC. Salidroside (p‐hydroxyphenethyl‐β‐D‐glucoside; SAL) has various biological and pharmacological activities, including anti‐inflammatory, ‐oxidant, and ‐cancer activities. However, the therapeutic effect and underlying molecular mechanism of SAL in NASH remain to be further clarified. Methods and Results: In this study, we found that SAL alleviated lipid accumulation and inflammatory response in primary hepatocytes after palmitic acid/oleic acid (PO) stimulation. In addition, SAL effectively prevented high‐fat/high‐cholesterol (HFHC)‐diet–induced NASH progression by regulating glucose metabolism dysregulation, insulin resistance, lipid accumulation, inflammation, and fibrosis. Mechanistically, integrated RNA‐sequencing and bioinformatic analysis showed that SAL promoted AMPK‐signaling pathway activation in vitro and in vivo, and this finding was further verified by determining the phosphorylation levels of AMPK. Furthermore, the protective effects of SAL on lipid accumulation and inflammation in hepatocytes and livers induced by PO or HFHC stimulation were blocked by AMPK interruption. Conclusions: Our studies demonstrate that SAL protects against metabolic‐stress–induced NASH progression through activation of AMPK signaling, indicating that SAL could be a potential drug component for NASH therapy.

Background and Aims: Although the prevalence of NAFLD has risen dramatically to 25% of the adult population worldwide, there are as yet no approved pharmacological interventions for the disease because of uncertainty about the underlying molecular mechanisms. It is known that mitochondrial dysfunction is an important factor in the development of NAFLD. Mitochondrial antiviral signaling protein (MAVS) is a critical signaling adaptor for host defenses against viral infection. However, the role of MAVS in mitochondrial metabolism during NAFLD progression remains largely unknown. Approach and Results: Based on expression analysis, we identified a marked down‐regulation of MAVS in hepatocytes during NAFLD progression. By using MAVS global knockout and hepatocyte‐specific MAVS knockout mice, we found that MAVS is protective against diet‐induced NAFLD. MAVS deficiency induces extensive mitochondrial dysfunction during NAFLD pathogenesis, which was confirmed as impaired mitochondrial respiratory capacity and membrane potential. Metabolomics data also showed the extensive metabolic disorders after MAVS deletion. Mechanistically, MAVS interacts with the N‐terminal stretch of voltage‐dependent anion channel 2 (VDAC2), which is required for the ability of MAVS to influence mitochondrial function and hepatic steatosis. Conclusions: In hepatocytes, MAVS plays an important role in protecting against NAFLD by helping to regulate healthy mitochondrial function. These findings provide insights regarding the metabolic importance of conventional immune regulators and support the possibility that targeting MAVS may represent an avenue for treating NAFLD.