Transferrin receptor levels and its rare variant are associated with human obesity.

AIM: Iron homeostasis is critical for functional respiratory chain complex of mitochondrial, thus potentially contributing to fat biology and energy homeostasis. Transferrin receptor (Tfrc) binds to transferrin for extracellular iron uptake and is recently reported to be involved in brown fat development and functionality. However, whether TFRC levels and variants are associated with human obesity is unknown. METHODS: To investigate the association of TFRC levels and variants with human obesity, fat biopsies were obtained from surgery. Exon-sequencing and genetic assessments were conducted of a case-control study. For TFRC levels assessment in fat biopsy, 9 overweight and 12 lean subjects were involved. For genetic study, obese (n = 1271) and lean subjects (n = 1455) were involved. TFRC levels were compared in abdominal mesenteric fat of pheochromocytoma patients versus control subjects, and overweight versus lean subjects. For genetic study, whole-exome sequencing of obese and matched control subjects were conducted and analyzed. In addition, the possible disruption in protein stability of TFRC variant was assessed by structural and molecular analysis. RESULTS: TFRC levels are increased in human browning adipose tissue and decreased in fat of overweight patients. Besides, TFRC levels are negatively correlated with body mass index and positively correlated with uncoupling protein 1 levels. Furthermore, a rare heterozygous missense variant p.I337V in TFRC shows a tendency to enrich in obese subjects. Structural and functional study reveals impaired protein stability of the TFRC variant compared to wild-type. CONCLUSIONS: Reduced TFRC levels and its rare variant p.I337V with protein instability are associated with human obesity.

Vascular smooth muscle cell-specific miRNA-214 deficiency alleviates simulated microgravity-induced vascular remodeling.

The human cardiovascular system has evolved to accommodate the gravity of Earth. Microgravity during spaceflight has been shown to induce vascular remodeling, leading to a decline in vascular function. The underlying mechanisms are not yet fully understood. Our previous study demonstrated that miR-214 plays a critical role in angiotensin II-induced vascular remodeling by reducing the levels of Smad7 and increasing the phosphorylation of Smad3. However, its role in vascular remodeling evoked by microgravity is not yet known. This study aimed to determine the contribution of miR-214 to the regulation of microgravity-induced vascular remodeling. The results of our study revealed that miR-214 expression was increased in the forebody arteries of both mice and monkeys after simulated microgravity treatment. In vitro, rotation-simulated microgravity-induced VSMC migration, hypertrophy, fibrosis, and inflammation were repressed by miR-214 knockout (KO) in VSMCs. Additionally, miR-214 KO increased the level of Smad7 and decreased the phosphorylation of Smad3, leading to a decrease in downstream gene expression. Furthermore, miR-214 cKO protected against simulated microgravity induced the decline in aorta function and the increase in stiffness. Histological analysis showed that miR-214 cKO inhibited the increases in vascular medial thickness that occurred after simulated microgravity treatment. Altogether, these results demonstrate that miR-214 has potential as a therapeutic target for the treatment of vascular remodeling caused by simulated microgravity.

Characterisation of forkhead box protein A3 as a key transcription factor for hepatocyte regeneration.

Background & Aims: Liver regeneration is vital for the recovery of liver function after injury, yet the underlying mechanism remains to be elucidated. Forkhead box protein A3 (FOXA3), a member of the forkhead box family, plays important roles in endoplasmic reticulum stress sensing, and lipid and glucose homoeostasis, yet its functions in liver regeneration are unknown. Methods: Here, we explored whether Foxa3 regulates liver regeneration via acute and chronic liver injury mice models. We further characterised the molecular mechanism by chromatin immunoprecipitation sequencing and rescue experiments in vivo and in vitro. Then, we assessed the impact of Foxa3 pharmacological activation on progression and termination of liver regeneration. Finally, we confirmed the Foxa3-Cebpb axis in human liver samples. Results: Foxa3 is dominantly expressed in hepatocytes and cholangiocytes and is induced upon partial hepatectomy (PH) or carbon tetrachloride (CCl4) administration. Foxa3 deficiency in mice decreased cyclin gene levels and delayed liver regeneration after PH, or acute or chronic i.p. CCl4 injection. Conversely, hepatocyte-specific Foxa3 overexpression accelerated hepatocytes proliferation and attenuated liver damage in an CCl4-induced acute model. Mechanistically, Foxa3 directly regulates Cebpb transcription, which is involved in hepatocyte division and apoptosis both in vivo and in vitro. Of note, Cebpb overexpression in livers of Foxa3-deficient mice rescued their defects in cell proliferation and regeneration upon CCl4 treatment. In addition, pharmacological induction of Foxa3 via cardamonin speeded up hepatocyte proliferation after PH, without interfering with liver regeneration termination. Finally, Cebpb and Ki67 levels had a positive correlation with Foxa3 expression in human chronic disease livers. Conclusions: These data characterise Foxa3 as a vital regulator of liver regeneration, which may represent an essential factor to maintain liver mass after liver injury by governing Cebpb transcription. Impact and Implications: Liver regeneration is vital for the recovery of liver function after chemical insults or hepatectomy, yet the underlying mechanism remains to be elucidated. Herein, via in vitro and in vivo models and analysis, we demonstrated that Forkhead box protein A3 (FOXA3), a Forkhead box family member, maintained normal liver regeneration progression by governing Cebpb transcription and proposed cardamonin as a lead compound to induce Foxa3 and accelerate liver repair, which signified that FOXA3 may be a potential therapeutic target for further preclinical study on treating liver injury.

AAV-Mediated nuclear localized PGC1α4 delivery in muscle ameliorates sarcopenia and aging-associated metabolic dysfunctions.

Sarcopenia is characterized of muscle mass loss and functional decline in elder individuals which severely affects human physical activity, metabolic homeostasis, and life quality. Physical exercise is considered effective in combating muscle atrophy and sarcopenia, yet it is not feasible to elders with limited mobility. PGC-1α4, a short isoform of PGC-1α, is strongly induced in muscle under resistance training, and promotes muscle hypertrophy. In the present study, we showed that the transcriptional levels and nuclear localization of PGC1α4 was reduced during aging, accompanied with muscle dystrophic morphology, and gene programs. We thus designed NLS-PGC1α4 and ectopically express it in myotubes to enhance PGC1α4 levels and maintain its location in nucleus. Indeed, NLS-PGC1α4 overexpression increased muscle sizes in myotubes. In addition, by utilizing AAV-NLS-PGC1α4 delivery into gastrocnemius muscle, we found that it could improve sarcopenia with grip strength, muscle weights, fiber size and molecular phenotypes, and alleviate age-associated adiposity, insulin resistance and hepatic steatosis, accompanied with altered gene signatures. Mechanistically, we demonstrated that NLS-PGC-1α4 improved insulin signaling and enhanced glucose uptake in skeletal muscle. Besides, via RNA-seq analysis, we identified myokines IGF1 and METRNL as potential targets of NLS-PGC-1α4 that possibly mediate the improvement of muscle and adipose tissue functionality and systemic energy metabolism in aged mice. Moreover, we found a negative correlation between PGC1α4 and age in human skeletal muscle. Together, our results revealed that NLS-PGC1α4 overexpression improves muscle physiology and systematic energy homeostasis during aging and suggested it as a potent therapeutic strategy against sarcopenia and aging-associated metabolic diseases.

Rna M6 a Methylation Regulates Glycolysis of Beige Fat and Contributes to Systemic Metabolic Homeostasis.

N6-methyladenosine (m6 A) modification has been implicated in the progression of obesity and metabolic diseases. However, its impact on beige fat biology is not well understood. Here, via m6 A-sequencing and RNA-sequencing, this work reports that upon beige adipocytes activation, glycolytic genes undergo major events of m6 A modification and transcriptional activation. Genetic ablation of m6 A writer Mettl3 in fat tissues reveals that Mettl3 deficiency in mature beige adipocytes leads to suppressed glycolytic capability and thermogenesis, as well as reduced preadipocytes proliferation via glycolytic product lactate. In addition, specific modulation of Mettl3 in beige fat via AAV delivery demonstrates consistently Mettl3's role in glucose metabolism, thermogenesis, and beige fat hyperplasia. Mechanistically, Mettl3 and m6 A reader Igf2bp2 control mRNA stability of key glycolytic genes in beige adipocytes. Overall, these findings highlight the significance of m6 A on fat biology and systemic energy homeostasis.

Selective PPARγ modulator diosmin improves insulin sensitivity and promotes browning of white fat.

Peroxisome proliferator-activated receptor γ (PPARγ) is a master regulator of adipocyte differentiation, glucolipid metabolism, and inflammation. Thiazolidinediones are PPARγ full agonists with potent insulin-sensitizing effects, whereas their oral usage is restricted because of unwanted side effects, including obesity and cardiovascular risks. Here, via virtual screening, microscale thermophoresis analysis, and molecular confirmation, we demonstrate that diosmin, a natural compound of wide and long-term clinical use, is a selective PPARγ modulator that binds to PPARγ and blocks PPARγ phosphorylation with weak transcriptional activity. Local diosmin administration in subcutaneous fat (inguinal white adipose tissue [iWAT]) improved insulin sensitivity and attenuated obesity via enhancing browning of white fat and energy expenditure. Besides, diosmin ameliorated inflammation in WAT and liver and reduced hepatic steatosis. Of note, we determined that iWAT local administration of diosmin did not exhibit obvious side effects. Taken together, the present study demonstrated that iWAT local delivery of diosmin protected mice from diet-induced insulin resistance, obesity, and fatty liver by blocking PPARγ phosphorylation, without apparent side effects, making it a potential therapeutic agent for the treatment of metabolic diseases.

Fibroblast Growth Factor 6 Promotes Adipocyte Progenitor Cell Proliferation for Adipose Tissue Homeostasis.

The de novo differentiation of hyperplastic adipocytes from adipocyte progenitor cells (APCs) is accompanied by a reduction in adipose tissue fibrosis and inflammation and improvement in insulin sensitivity in obesity and aging. However, the regulators of APC proliferation are poorly understood. Here, we show that fibroblast growth factor 6 (FGF6) acts in an autocrine and/or paracrine manner to control platelet-derived growth factor receptor α-positive APC proliferation via extracellular signal-regulated kinase (ERK) signaling. Specific FGF6 overexpression in inguinal white adipose tissue (iWAT) improved the signs of high-fat diet- or aging-induced adipose hypertrophy and insulin resistance. Conversely, chronic FGF6 expression blockade in iWAT, mediated by a neutralizing antibody or Fgf6 expression deficiency, impaired adipose tissue expansion and glucose tolerance. Overall, our data suggest that FGF6 acts as a proliferative factor for APCs to maintain fat homeostasis and insulin sensitivity.

GPSM1 impairs metabolic homeostasis by controlling a pro-inflammatory pathway in macrophages.

G-protein-signaling modulator 1 (GPSM1) exhibits strong genetic association with Type 2 diabetes (T2D) and Body Mass Index in population studies. However, how GPSM1 carries out such control and in which types of cells are poorly understood. Here, we demonstrate that myeloid GPSM1 promotes metabolic inflammation to accelerate T2D and obesity development. Mice with myeloid-specific GPSM1 ablation are protected against high fat diet-induced insulin resistance, glucose dysregulation, and liver steatosis via repression of adipose tissue pro-inflammatory states. Mechanistically, GPSM1 deficiency mainly promotes TNFAIP3 transcription via the Gαi3/cAMP/PKA/CREB axis, thus inhibiting TLR4-induced NF-κB signaling in macrophages. In addition, we identify a small-molecule compound, AN-465/42243987, which suppresses the pro-inflammatory phenotype by inhibiting GPSM1 function, which could make it a candidate for metabolic therapy. Furthermore, GPSM1 expression is upregulated in visceral fat of individuals with obesity and is correlated with clinical metabolic traits. Overall, our findings identify macrophage GPSM1 as a link between metabolic inflammation and systemic homeostasis.

Osteoblast Derived Exosomes Alleviate Radiation- Induced Hematopoietic Injury.

As hematopoietic stem cells can differentiate into all hematopoietic lineages, mitigating the damage to hematopoietic stem cells is important for recovery from overdose radiation injury. Cells in bone marrow microenvironment are essential for hematopoietic stem cells maintenance and protection, and many of the paracrine mediators have been discovered in shaping hematopoietic function. Several recent reports support exosomes as effective regulators of hematopoietic stem cells, but the role of osteoblast derived exosomes in hematopoietic stem cells protection is less understood. Here, we investigated that osteoblast derived exosomes could alleviate radiation damage to hematopoietic stem cells. We show that intravenous injection of osteoblast derived exosomes promoted WBC, lymphocyte, monocyte and hematopoietic stem cells recovery after irradiation significantly. By sequencing osteoblast derived exosomes derived miRNAs and verified in vitro, we identified miR-21 is involved in hematopoietic stem cells protection via targeting PDCD4. Collectively, our data demonstrate that osteoblast derived exosomes derived miR-21 is a resultful regulator to radio-protection of hematopoietic stem cells and provide a new strategy for reducing radiation induced hematopoietic injury.

Anoctamin 1 controls bone resorption by coupling Cl- channel activation with RANKL-RANK signaling transduction.

Osteoclast over-activation leads to bone loss and chloride homeostasis is fundamental importance for osteoclast function. The calcium-activated chloride channel Anoctamin 1 (also known as TMEM16A) is an important chloride channel involved in many physiological processes. However, its role in osteoclast remains unresolved. Here, we identified the existence of Anoctamin 1 in osteoclast and show that its expression positively correlates with osteoclast activity. Osteoclast-specific Anoctamin 1 knockout mice exhibit increased bone mass and decreased bone resorption. Mechanistically, Anoctamin 1 deletion increases intracellular Cl- concentration, decreases H+ secretion and reduces bone resorption. Notably, Anoctamin 1 physically interacts with RANK and this interaction is dependent upon Anoctamin 1 channel activity, jointly promoting RANKL-induced downstream signaling pathways. Anoctamin 1 protein levels are substantially increased in osteoporosis patients and this closely correlates with osteoclast activity. Finally, Anoctamin 1 deletion significantly alleviates ovariectomy induced osteoporosis. These results collectively establish Anoctamin 1 as an essential regulator in osteoclast function and suggest a potential therapeutic target for osteoporosis.

Comprehensive Transcriptome Profiling of NAFLD- and NASH-Induced Skeletal Muscle Dysfunction.

Nonalcoholic fatty liver disease (NAFLD), characterized by extensive triglyceride accumulation in hepatocytes, may progress to nonalcoholic steatohepatitis (NASH) with liver fibrosis and inflammation and increase the risk of cirrhosis, cancer, and death. It has been reported that physical exercise is effective in ameliorating NAFLD and NASH, while skeletal muscle dysfunctions, including lipid deposition and weakness, are accompanied with NAFLD and NASH. However, the molecular characteristics and alterations in skeletal muscle in the progress of NAFLD and NASH remain unclear. In the present study, we provide a comprehensive analysis on the similarity and heterogeneity of quadriceps muscle in NAFLD and NASH mice models by RNA sequencing. Importantly, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway functional enrichment analysis revealed that NAFLD and NASH led to impaired glucose and lipid metabolism and deteriorated functionality in skeletal muscle. Besides this, we identified that myokines possibly mediate the crosstalk between muscles and other metabolic organs in pathological conditions. Overall, our analysis revealed a comprehensive understanding of the molecular signature of skeletal muscles in NAFLD and NASH, thus providing a basis for physical exercise as an intervention against liver diseases.

The mechanosensitive lncRNA Neat1 promotes osteoblast function through paraspeckle-dependent Smurf1 mRNA retention.

Mechanical stimulation plays an important role in bone remodeling. Exercise-induced mechanical loading enhances bone strength, whereas mechanical unloading leads to bone loss. Increasing evidence has demonstrated that long noncoding RNAs (lncRNAs) play key roles in diverse biological, physiological and pathological contexts. However, the roles of lncRNAs in mechanotransduction and their relationships with bone formation remain unknown. In this study, we screened mechanosensing lncRNAs in osteoblasts and identified Neat1, the most clearly decreased lncRNA under simulated microgravity. Of note, not only Neat1 expression but also the specific paraspeckle structure formed by Neat1 was sensitive to different mechanical stimulations, which were closely associated with osteoblast function. Paraspeckles exhibited small punctate aggregates under simulated microgravity and elongated prolate or larger irregular structures under mechanical loading. Neat1 knockout mice displayed disrupted bone formation, impaired bone structure and strength, and reduced bone mass. Neat1 deficiency in osteoblasts reduced the response of osteoblasts to mechanical stimulation. In vivo, Neat1 knockout in mice weakened the bone phenotypes in response to mechanical loading and hindlimb unloading stimulation. Mechanistically, paraspeckles promoted nuclear retention of E3 ubiquitin ligase Smurf1 mRNA and downregulation of their translation, thus inhibiting ubiquitination-mediated degradation of the osteoblast master transcription factor Runx2, a Smurf1 target. Our study revealed that Neat1 plays an essential role in osteoblast function under mechanical stimulation, which provides a paradigm for the function of the lncRNA-assembled structure in response to mechanical stimulation and offers a therapeutic strategy for long-term spaceflight- or bedrest-induced bone loss and age-related osteoporosis.

Nuclear UHRF1 is a gate-keeper of cellular AMPK activity and function.

The AMP-activated protein kinase (AMPK) is a central regulator of energy homeostasis. Although much has been learned on how low energy status and glucose starvation activate AMPK, how AMPK activity is properly controlled in vivo is still poorly understood. Here we report that UHRF1, an epigenetic regulator highly expressed in proliferating and cancer cells, interacts with AMPK and serves to suppress AMPK activity under both basal and stressed conditions. As a nuclear protein, UHRF1 promotes AMPK nuclear retention and strongly suppresses nuclear AMPK activity toward substrates H2B and EZH2. Importantly, we demonstrate that UHRF1 also robustly inhibits AMPK activity in the cytoplasm compartment, most likely as a consequence of AMPK nucleocytoplasmic shuttling. Mechanistically, we found that UHRF1 has no obvious effect on AMPK activation by upstream kinases LKB1 and CAMKK2 but inhibits AMPK activity by acting as a bridging factor targeting phosphatase PP2A to dephosphorylate AMPK. Hepatic overexpression of UHRF1 showed profound effects on glucose and lipid metabolism in wild-type mice but not in those with the liver-specific knockout of AMPKα1/α2, whereas knockdown of UHRF1 in adipose tissue led to AMPK activation and reduced sizes of adipocytes and lipogenic activity, highlighting the physiological significance of this regulation in glucose and lipid metabolism. Thus, our study identifies UHRF1 as a novel AMPK gate-keeper with critical roles in cellular metabolism.

Vascular smooth muscle cell-specific miRNA-214 knockout inhibits angiotensin II-induced hypertension through upregulation of Smad7.

Vascular remodeling is a prominent trait during the development of hypertension, attributable to the phenotypic transition of vascular smooth muscle cells (VSMCs). Increasing studies demonstrate that microRNA plays an important role in this process. Here, we surprisingly found that smooth muscle cell-specific miR-214 knockout (miR-214 cKO) significantly alleviates angiotensin II (Ang II)-induced hypertension, which has the same effect as that of miR-214 global knockout mice in response to Ang II stimulation. Under the treatment of Ang II, miR-214 cKO mice exhibit substantially reduced systolic blood pressure. The vascular medial thickness and area in miR-214 cKO blood vessels were obviously reduced, the expression of collagen I and proinflammatory factors were also inhibited. VSMC-specific deletion of miR-214 blunts the response of blood vessels to the stimulation of endothelium-dependent and -independent vasorelaxation and phenylephrine and 5-HT induced vasocontraction. In vitro, Ang II-induced VSMC proliferation, migration, contraction, hypertrophy, and stiffness were all repressed with miR-214 KO in VSMC. To further explore the mechanism of miR-214 in the regulation of the VSMC function, it is very interesting to find that the TGF-ß signaling pathway is mostly enriched in miR-214 KO VSMC. Smad7, the potent negative regulator of the TGF-ß/Smad pathway, is identified to be the target of miR-214 in VSMC. By which, miR-214 KO sharply enhances Smad7 levels and decreases the phosphorylation of Smad3, and accordingly alleviates the downstream gene expression. Further, Ang II-induced hypertension and vascular dysfunction were reversed by antagomir-214. These results indicate that miR-214 in VSMC established a crosstalk between Ang II-induced AT1R signaling and TGF-ß induced TßRI /Smad signaling, by which it exerts a pivotal role in vascular remodeling and hypertension and imply that miR-214 has the potential as a therapeutic target for the treatment of hypertension.

Skeletal muscle-targeted delivery of Fgf6 protects mice from diet-induced obesity and insulin resistance.

Obesity, a major health care issue, is characterized by metabolic abnormalities in multiple tissues, including the skeletal muscle. Although dysregulation of skeletal muscle metabolism can strongly influence the homeostasis of systemic energy, the underlying mechanism remains unclear. We found promoter hypermethylation and decreased gene expression of fibroblast growth factor 6 (FGF6) in the skeletal muscle of individuals with obesity using high-throughput sequencing. Reduced binding of the cyclic AMP responsive element binding protein-1 (CREB1) to the hypermethylated cyclic AMP response element, which is a regulatory element upstream of the transcription initiation site, partially contributed to the downregulation of FGF6 in patients with obesity. Overexpression of Fgf6 in mouse skeletal muscle stimulated protein synthesis, activating the mammalian target of rapamycin pathway, and prevented the increase in weight and the development of insulin resistance in high-fat diet-fed mice. Thus, our findings highlight the role played by Fgf6 in regulating skeletal muscle hypertrophy and whole-body metabolism, indicating its potential in strategies aimed at preventing and treating metabolic diseases.

3' untranslated region of Ckip-1 inhibits cardiac hypertrophy independently of its cognate protein.

AIMS: 3' untranslated region (3' UTR) of mRNA is more conserved than other non-coding sequences in vertebrate genomes, and its sequence space has substantially expanded during the evolution of higher organisms, which substantiates their significance in biological regulation. However, the independent role of 3' UTR in cardiovascular disease was largely unknown. METHODS AND RESULTS: Using bioinformatics, RNA fluorescent in situ hybridization and quantitative real-time polymerase chain reaction, we found that 3' UTR and coding sequence regions of Ckip-1 mRNA exhibited diverse expression and localization in cardiomyocytes. We generated cardiac-specific Ckip-1 3' UTR overexpression mice under wild type and casein kinase 2 interacting protein-1 (CKIP-1) knockout background. Cardiac remodelling was assessed by histological, echocardiography, and molecular analyses at 4 weeks after transverse aortic constriction (TAC) surgery. The results showed that cardiac Ckip-1 3' UTR significantly inhibited TAC-induced cardiac hypertrophy independent of CKIP-1 protein. To determine the mechanism of Ckip-1 3' UTR in cardiac hypertrophy, we performed transcriptome and metabolomics analyses, RNA immunoprecipitation, biotin-based RNA pull-down, and reporter gene assays. We found that Ckip-1 3' UTR promoted fatty acid metabolism through AMPK-PPARα-CPT1b axis, leading to its protection against pathological cardiac hypertrophy. Moreover, Ckip-1 3' UTR RNA therapy using adeno-associated virus obviously alleviates cardiac hypertrophy and improves heart function. CONCLUSIONS: These findings disclose that Ckip-1 3' UTR inhibits cardiac hypertrophy independently of its cognate protein. Ckip-1 3' UTR is an effective RNA-based therapy tool for treating cardiac hypertrophy and heart failure.

Targeting E3 Ubiquitin Ligase WWP1 Prevents Cardiac Hypertrophy Through Destabilizing DVL2 via Inhibition of K27-Linked Ubiquitination.

BACKGROUND: Without adequate treatment, pathological cardiac hypertrophy induced by sustained pressure overload eventually leads to heart failure. WWP1 (WW domain-containing E3 ubiquitin protein ligase 1) is an important regulator of aging-related pathologies, including cancer and cardiovascular diseases. However, the role of WWP1 in pressure overload-induced cardiac remodeling and heart failure is yet to be determined. METHODS: To examine the correlation of WWP1 with hypertrophy, we analyzed WWP1 expression in patients with heart failure and mice subjected to transverse aortic constriction (TAC) by Western blotting and immunohistochemical staining. TAC surgery was performed on WWP1 knockout mice to assess the role of WWP1 in cardiac hypertrophy, heart function was examined by echocardiography, and related cellular and molecular markers were examined. Mass spectrometry and coimmunoprecipitation assays were conducted to identify the proteins that interacted with WWP1. Pulse-chase assay, ubiquitination assay, reporter gene assay, and an in vivo mouse model via AAV9 (adeno-associated virus serotype 9) were used to explore the mechanisms by which WWP1 regulates cardiac remodeling. AAV9 carrying cardiac troponin T (cTnT) promoter-driven small hairpin RNA targeting WWP1 (AAV9-cTnT-shWWP1) was administered to investigate its rescue role in TAC-induced cardiac dysfunction. RESULTS: The WWP1 level was significantly increased in the hypertrophic hearts from patients with heart failure and mice subjected to TAC. The results of echocardiography and histology demonstrated that WWP1 knockout protected the heart from TAC-induced hypertrophy. There was a direct interaction between WWP1 and DVL2 (disheveled segment polarity protein 2). DVL2 was stabilized by WWP1-mediated K27-linked polyubiquitination. The role of WWP1 in pressure overload-induced cardiac hypertrophy was mediated by the DVL2/CaMKII/HDAC4/MEF2C signaling pathway. Therapeutic targeting WWP1 almost abolished TAC induced heart dysfunction, suggesting WWP1 as a potential target for treating cardiac hypertrophy and failure. CONCLUSIONS: We identified WWP1 as a key therapeutic target for pressure overload induced cardiac remodeling. We also found a novel mechanism regulated by WWP1. WWP1 promotes atypical K27-linked ubiquitin multichain assembly on DVL2 and exacerbates cardiac hypertrophy by the DVL2/CaMKII/HDAC4/MEF2C pathway.

FOXA3 induction under endoplasmic reticulum stress contributes to non-alcoholic fatty liver disease.

BACKGROUND & AIMS: Chronic endoplasmic reticulum (ER) stress in the liver has been shown to play a causative role in non-alcoholic fatty liver disease (NAFLD) progression, yet the underlying molecular mechanisms remain to be elucidated. Forkhead box A3 (FOXA3), a member of the FOX family, plays critical roles in metabolic homeostasis, although its possible functions in ER stress and fatty liver progression are unknown. METHODS: Adenoviral delivery, siRNA delivery, and genetic knockout mice were used to crease FOXA3 gain- or loss-of-function models. Tunicamycin (TM) and a high-fat diet (HFD) were used to induce acute or chronic ER stress in mice. Chromatin immunoprecipiation (ChIP)-seq, luciferase assay, and adenoviral-mediated downstream gene manipulations were performed to reveal the transcriptional axis involved. Key axis protein levels in livers from healthy donors and patients with NAFLD were assessed via immunohistochemical staining. RESULTS: FOXA3 transcription is specifically induced by XBP1s upon ER stress. FOXA3 exacerbates the excessive lipid accumulation caused by the acute ER-inducer TM, whereas FOXA3 deficiency in hepatocytes and mice alleviates it. Importantly, FOXA3 deficiency in mice reduced diet-induced chronic ER stress, fatty liver, and insulin resistance. In addition, FOXA3 suppression via siRNA or adeno-associated virus delivery ameliorated the fatty liver phenotype in HFD-fed and db/db mice. Mechanistically, ChIP-Seq analysis revealed that FOXA3 directly regulates Period1 (Per1) transcription, which in turn promotes the expression of lipogenic genes, including Srebp1c, thus enhancing lipid synthesis. Of pathophysiological significance, FOXA3, PER1, and SREBP1c levels were increased in livers of obese mice and patients with NAFLD. CONCLUSION: The present study identified FOXA3 as the bridging molecule that links ER stress and NAFLD progression. Our results highlighted the role of the XBP1s-FOXA3-PER1/Srebp1c transcriptional axis in the development of NAFLD and identified FOXA3 as a potential therapeutic target for fatty liver disease. LAY SUMMARY: The molecular mechanisms linking endoplasmic reticulum stress to non-alcoholic fatty liver disease (NAFLD) progression remain undefined. Herein, via in vitro and in vivo analysis, we identified Forkhead box A3 (FOXA3) as a key bridging molecule. Of pathophysiological significance, FOXA3 protein levels were increased in livers of obese mice and patients with NAFLD, indicating that FOXA3 could be a potential therapeutic target in fatty liver disease.

Breast cancer exosomes contribute to pre-metastatic niche formation and promote bone metastasis of tumor cells.

Rationale: Breast cancer preferentially develops osteolytic bone metastasis, which makes patients suffer from pain, fractures and spinal cord compression. Accumulating evidences have shown that exosomes play an irreplaceable role in pre-metastatic niche formation as a communication messenger. However, the function of exosomes secreted by breast cancer cells remains incompletely understood in bone metastasis of breast cancer. Methods: Mouse xenograft models and intravenous injection of exosomes were applied for analyzing the role of breast cancer cell-derived exosomes in vivo. Effects of exosomes secreted by the mildly metastatic MDA231 and its subline SCP28 with highly metastatic ability on osteoclasts formation were confirmed by TRAP staining, ELISA, microcomputed tomography, histomorphometric analyses, and pit formation assay. The candidate exosomal miRNAs for promoting osteoclastogenesis were globally screened by RNA-seq. qRT-PCR, western blot, confocal microscopy, and RNA interfering were performed to validate the function of exosomal miRNA. Results: Implantation of SCP28 tumor cells in situ leads to increased osteoclast activity and reduced bone density, which contributes to the formation of pre-metastatic niche for tumor cells. We found SCP28 cells-secreted exosomes are critical factors in promoting osteoclast differentiation and activation, which consequently accelerates bone lesion to reconstruct microenvironment for bone metastasis. Mechanistically, exosomal miR-21 derived from SCP28 cells facilitates osteoclastogenesis through regulating PDCD4 protein levels. Moreover, miR-21 level in serum exosomes of breast cancer patients with bone metastasis is significantly higher than that in other subpopulations. Conclusion: Our results indicate that breast cancer cell-derived exosomes play an important role in promoting breast cancer bone metastasis, which is associated with the formation of pre-metastatic niche via transferring miR-21 to osteoclasts. The data from patient samples further reflect the significance of miR-21 as a potential target for clinical diagnosis and treatment of breast cancer bone metastasis.

Ckip-1 3'-UTR Attenuates Simulated Microgravity-Induced Cardiac Atrophy.

Microgravity prominently affected cardiovascular health, which was the gravity-dependent physical factor. Deep space exploration had been increasing in frequency, but heart function was susceptible to conspicuous damage and cardiac mass declined in weightlessness. Understanding of the etiology of cardiac atrophy exposed to microgravity currently remains limited. The 3'-untranslated region (UTR) of casein kinase-2 interacting protein-1 (Ckip-1) was a pivotal mediator in pressure overload-induced cardiac remodeling. However, the role of Ckip-1 3'-UTR in the heart during microgravity was unknown. We analyzed Ckip-1 mRNA 3'-UTR and coding sequence (CDS) expression levels in ground-based analogs such as mice hindlimb unloading (HU) and rhesus monkey head-down bed rest model. Ckip-1 3'-UTR had transcribed levels in the opposite change trend with cognate CDS expression in the hearts. We then subjected wild-type (WT) mice and cardiac-specific Ckip-1 3'-UTR-overexpressing mice to hindlimb unloading for 28 days. Our results uncovered that Ckip-1 3'-UTR remarkably attenuated cardiac dysfunction and mass loss in simulated microgravity environments. Mechanistically, Ckip-1 3'-UTR inhibited lipid accumulation and elevated fatty acid oxidation-related gene expression in the hearts through targeting calcium/calmodulin-dependent kinase 2 (CaMKK2) and activation of the AMPK-PPARα-CPT1b signaling pathway. These findings demonstrated Ckip-1 3'-UTR was an important regulator in atrophic heart growth after simulated microgravity.