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Invariant natural killer T (iNKT) cells are a group of innate-like T lymphocytes that recognize lipid antigens. They are supposed to be tissue resident and important for systemic and local immune regulation. To investigate the heterogeneity of iNKT cells, we recharacterized iNKT cells in the thymus and peripheral tissues. iNKT cells in the thymus were divided into three subpopulations by the expression of the natural killer cell receptor CD244 and the chemokine receptor CXCR6 and designated as C0 (CD244⁻CXCR6⁻), C1 (CD244⁻CXCR6⁺), or C2 (CD244⁺CXCR6⁺) iNKT cells. The development and maturation of C2 iNKT cells from C0 iNKT cells strictly depended on IL-15 produced by thymic epithelial cells. C2 iNKT cells expressed high levels of IFN-γ and granzymes and exhibited more NK cell–like features, whereas C1 iNKT cells showed more T cell–like characteristics. C2 iNKT cells were influenced by the microbiome and aging and suppressed the expression of the autoimmune regulator AIRE in the thymus. In peripheral tissues, C2 iNKT cells were circulating that were distinct from conventional tissue-resident C1 iNKT cells. Functionally, C2 iNKT cells protected mice from the tumor metastasis of melanoma cells by enhancing antitumor immunity and promoted antiviral immune responses against influenza virus infection. Furthermore, we identified human CD244⁺CXCR6⁺ iNKT cells with high cytotoxic properties as a counterpart of mouse C2 iNKT cells. Thus, this study reveals a circulating subset of iNKT cells with NK cell–like properties distinct from conventional tissue-resident iNKT cells., 新規の循環型iNKT細胞を発見 --抗腫瘍・抗ウイルス感染効果の高い免疫細胞療法の開発への貢献に期待--. 京都大学プレスリリース. 2022-10-24.

Peritoneal metastasis is a common mode of spread of ovarian cancer. Despite therapeutic advances, some patients have intractable peritoneal metastasis. Therefore, in-depth characterization of the molecular mechanism of peritoneal metastasis is a key imperative. Angiopoietin-like protein 2 (ANGPTL2) is an inflammatory factor which activates NF-κB signaling and plays an important role in the pathogenesis of various inflammatory diseases including cancers, such as lung and breast cancer. In this study, we examined the role of ANGPTL2 in ovarian cancer peritoneal metastasis. We observed no difference of cell proliferation between ANGPTL2-expressing and control cells. In the mouse intraperitoneal xenograft model, formation of peritoneal metastasis by ANGPTL2-expressing cells was significantly decreased compared to control. In the in vitro analysis, the expressions of integrin α5β1, α6, and β4, but not those of αvβ3, α3, α4, and β1, were significantly decreased in ANGPTL2-expressing cells compared to control cells. ANGPTL2-expressing cells showed significantly inhibited adherence to laminin compared to control. In addition, we observed upregulation of anoikis (a form of programmed cell death occurring under an anchorage-independent condition) and significant decrease in the expression of Bcl-2 in ANGPTL2-expressing cells as compared to control cells. These results suggest that ANGPTL2 expression in ovarian cancer cells represses peritoneal metastasis by suppressing anoikis resistance.

In the past decade, many long noncoding RNAs (lncRNAs) have been identified and their in vitro functions defined, although in some cases their functions in vivo remain less clear. Moreover, unlike nuclear lncRNAs, the roles of cytoplasmic lncRNAs are less defined. Here, using a gene trapping approach in mouse embryonic stem cells, we identify Caren (short for cardiomyocyte-enriched noncoding transcript), a cytoplasmic lncRNA abundantly expressed in cardiomyocytes. Caren maintains cardiac function under pathological stress by inactivating the ataxia telangiectasia mutated (ATM)-DNA damage response (DDR) pathway and activating mitochondrial bioenergetics. The presence of Caren transcripts does not alter expression of nearby (cis) genes but rather decreases translation of an mRNA transcribed from a distant gene encoding histidine triad nucleotide-binding protein 1 (Hint1), which activates the ATM-DDR pathway and reduces mitochondrial respiratory capacity in cardiomyocytes. Therefore, the cytoplasmic lncRNA Caren functions in cardioprotection by regulating translation of a distant gene and maintaining cardiomyocyte homeostasis., Long noncoding RNAs (lncRNAs) have been shown to play a role in cardiac physiology and disease. Here the authors identify the lncRNA Caren as a cytoplasmic RNA that decreases the translation of a distant gene encoding Hint1, thereby maintaining cardiomyocyte function due to inactivation of the DNA damage response and activation of mitochondrial bioenergetics.

Sirtuins (SIRT1–7 in mammals) are evolutionarily conserved nicotinamide adenine dinucleotide-dependent lysine deacetylases/deacylases that regulate fundamental biological processes including aging. In this study, we reveal that male Sirt7 knockout (KO) mice exhibited an extension of mean and maximum lifespan and a delay in the age-associated mortality rate. In addition, aged male Sirt7 KO mice displayed better glucose tolerance with improved insulin sensitivity compared with wild-type (WT) mice. Fibroblast growth factor 21 (FGF21) enhances insulin sensitivity and extends lifespan when it is overexpressed. Serum levels of FGF21 were markedly decreased with aging in WT mice. In contrast, this decrease was suppressed in Sirt7 KO mice, and the serum FGF21 levels of aged male Sirt7 KO mice were higher than those of WT mice. Activating transcription factor 4 (ATF4) stimulates Fgf21 transcription, and the hepatic levels of Atf4 mRNA were increased in aged male Sirt7 KO mice compared with WT mice. Our findings indicate that the loss of SIRT7 extends lifespan and improves glucose metabolism in male mice. High serum FGF21 levels might be involved in the beneficial effect of SIRT7 deficiency.

Uncontrolled proliferation of intestinal epithelial cells caused by mutations in genes of the WNT/β-catenin pathway is associated with development of intestinal cancers. We previously reported that intestinal stromal cell-derived angiopoietin-like protein 2 (ANGPTL2) controls epithelial regeneration and intestinal immune responses. However, the role of tumor cell-derived ANGPTL2 in intestinal tumorigenesis remained unclear. Here, we show that tumor cell-derived ANGPTL2 promotes β-catenin-driven intestinal tumorigenesis. ANGPTL2 deficiency suppressed intestinal tumor development in an experimental mouse model of sporadic colon cancer. We also found that increased ANGPTL2 expression in colorectal cancer (CRC) cells augments β-catenin pathway signaling and promotes tumor cell proliferation. Relevant to mechanism, our findings suggest that tumor cell-derived ANGPTL2 upregulates expression of OB-cadherin, which then interacts with β-catenin, blocking destruction complex-independent proteasomal degradation of β-catenin proteins. Moreover, our observations support a model whereby ANGPTL2-induced OB-cadherin expression in CRC cells is accompanied by decreased cell surface integrin α5β1 expression. These findings overall provide novel insight into mechanisms of β-catenin-driven intestinal tumorigenesis.

Renal cell carcinoma (RCC) associated with Xp11.2 translocation (TFE3-RCC) has been recently defined as a distinct subset of RCC classified by characteristic morphology and clinical presentation. The Xp11 translocations involve the TFE3 transcription factor and produce chimeric TFE3 proteins retaining the basic helix–loop–helix leucine zipper structure for dimerization and DNA binding suggesting that chimeric TFE3 proteins function as oncogenic transcription factors. Diagnostic biomarkers and effective forms of therapy for advanced cases of TFE3-RCC are as yet unavailable. To facilitate the development of molecular based diagnostic tools and targeted therapies for this aggressive kidney cancer, we generated a translocation RCC mouse model, in which the PRCC-TFE3 transgene is expressed specifically in kidneys leading to the development of RCC with characteristic histology. Expression of the receptor tyrosine kinase Ret was elevated in the kidneys of the TFE3-RCC mice, and treatment with RET inhibitor, vandetanib, significantly suppressed RCC growth. Moreover, we found that Gpnmb (Glycoprotein nonmetastatic B) expression was notably elevated in the TFE3-RCC mouse kidneys as seen in human TFE3-RCC tumors, and confirmed that GPNMB is the direct transcriptional target of TFE3 fusions. While GPNMB IHC staining was positive in 9/9 cases of TFE3-RCC, Cathepsin K, a conventional marker for TFE3-RCC, was positive in only 67% of cases. These data support RET as a potential target and GPNMB as a diagnostic marker for TFE3-RCC. The TFE3-RCC mouse provides a preclinical in vivo model for the development of new biomarkers and targeted therapeutics for patients affected with this aggressive form of RCC. Implications: Key findings from studies with this preclinical mouse model of TFE3-RCC underscore the potential for RET as a therapeutic target for treatment of patients with TFE3-RCC, and suggest that GPNMB may serve as diagnostic biomarker for TFE3 fusion RCC.

Whole-body metabolic homeostasis is tightly controlled by hormone-like factors with systemic or paracrine effects that are derived from nonendocrine organs, including adipose tissue (adipokines) and liver (hepatokines). Fibroblast growth factor 21 (FGF21) is a hormone-like protein, which is emerging as a major regulator of whole-body metabolism and has therapeutic potential for treating metabolic syndrome. However, the mechanisms that control FGF21 levels are not fully understood. Herein, we demonstrate that FGF21 production in the liver is regulated via a posttranscriptional network consisting of the CCR4–NOT deadenylase complex and RNA-binding protein tristetraprolin (TTP). In response to nutrient uptake, CCR4–NOT cooperates with TTP to degrade AU-rich mRNAs that encode pivotal metabolic regulators, including FGF21. Disruption of CCR4–NOT activity in the liver, by deletion of the catalytic subunit CNOT6L, increases serum FGF21 levels, which ameliorates diet-induced metabolic disorders and enhances energy expenditure without disrupting bone homeostasis. Taken together, our study describes a hepatic CCR4–NOT/FGF21 axis as a hitherto unrecognized systemic regulator of metabolism and suggests that hepatic CCR4–NOT may serve as a target for devising therapeutic strategies in metabolic syndrome and related morbidities.

Sunburn causes inflammation, which increases melanin production in skin and causes hyperpigmentation. Angiopoietin‐like protein (ANGPTL) 2 is an inflammatory mediator induced in sun‐exposed skin areas. However, whether ANGPTL2 functions in melanin production remains unclear. To assess this possibility, we overexpressed Angptl2 in the melanoma line B16 and in the keratinocyte line HaCaT. Relative to controls, Angptl2‐expressing B16 cells produced higher melanin levels via tyrosinase induction. Accordingly, Angptl2‐expressing HaCaT cells secreted relatively high levels of both endothelin‐1 (ET‐1) and α‐melanocyte‐stimulating hormone (α‐MSH). Moreover, treatment with an extract from Chrysanthemum indicum × Erigeron annuus (CE) suppressed ANGPTL2 expression and repressed tyrosinase induction in melanocytes and of α‐MSH and ET‐1 in keratinocytes. Our data suggest that ANGPTL2 expression in keratinocytes and melanin‐producing cells accelerates pigment production and that treatment of skin with a CE extract could prevent melanin accumulation.

The hypothalamic regulation of appetite governs whole-body energy balance. Satiety is regulated by endocrine factors including leptin, and impaired leptin signaling is associated with obesity. Despite the anorectic effect of leptin through the regulation of the hypothalamic feeding circuit, a distinct downstream mediator of leptin signaling in neuron remains unclear. Angiopoietin-like growth factor (AGF) is a peripheral activator of energy expenditure and antagonizes obesity. However, the regulation of AGF expression in brain and localization to mediate anorectic signaling is unknown. Here, we demonstrated that AGF is expressed in proopiomelanocortin (POMC)-expressing neurons located in the arcuate nucleus (ARC) of the hypothalamus. Unlike other brain regions, hypothalamic AGF expression is stimulated by leptin-induced signal transducers and activators of transcription 3 (STAT3) phosphorylation. In addition, leptin treatment to hypothalamic N1 cells significantly enhanced the promoter activity of AGF. This induction was abolished by the pretreatment of ruxolitinib, a leptin signaling inhibitor. These results indicate that hypothalamic AGF expression is induced by leptin and colocalized to POMC neurons.

The lateral ventricle (LV) is flanked by the subventricular zone (SVZ), a neural stem cell (NSC) niche rich in extrinsic growth factors regulating NSC maintenance, proliferation, and neuronal differentiation. Dysregulation of the SVZ niche causes LV expansion, a condition known as hydrocephalus; however, the underlying pathological mechanisms are unclear. We show that deficiency of the proteoglycan Tsukushi (TSK) in ependymal cells at the LV surface and in the cerebrospinal fluid results in hydrocephalus with neurodevelopmental disorder-like symptoms in mice. These symptoms are accompanied by altered differentiation and survival of the NSC lineage, disrupted ependymal structure, and dysregulated Wnt signaling. Multiple TSK variants found in patients with hydrocephalus exhibit reduced physiological activity in mice in vivo and in vitro. Administration of wild-type TSK protein or Wnt antagonists, but not of hydrocephalus-related TSK variants, in the LV of TSK knockout mice prevented hydrocephalus and preserved SVZ neurogenesis. These observations suggest that TSK plays a crucial role as a niche molecule modulating the fate of SVZ NSCs and point to TSK as a candidate for the diagnosis and therapy of hydrocephalus.

Previous studies show that tumor cell-derived angiopoietin-like protein 2 (ANGPTL2) functions as a tumor promoter in some cancer contexts. However, we recently reported that host ANGPTL2 also shows tumor suppressive activity by enhancing dendritic cell-mediated CD8

Adipose tissue (AT) contains well-developed vascular networks. Pathological AT expansion often accompany the reduction in AT blood vessels, which further exacerbates adipocyte dysfunction due to hypoxia; however, it remains unclear whether AT vascular rarefaction is simply secondary to adipocyte hypertrophy, or if there is an actively regulated pathway that mediates impaired AT angiogenesis in obesity. We searched for growth factors whose expression in AT is down-regulated in obesity; accordingly, we identified neuregulin-4 (Nrg4), a member of the EGF family of proteins. Nrg4 is highly and preferentially expressed in healthy adipocytes, while its expression was substantially reduced in obesity. Nrg4 activated endothelial angiogenic functions and angiogenesis both in vitro and in vivo. Genetic loss of Nrg4 caused reduction in brown and white AT blood vessels, and induced overweight even while consuming normal chow. Conditional knockout of Nrg4 in brown adipocytes caused blood vessel reduction in brown but not in white AT, and was sufficient to induce obese phenotype. Our data demonstrated that Nrg4 plays a critical role in maintaining AT vasculature and its metabolic functions. Considering the substantial reduction of Nrg4 in obesity, disruption of Nrg4-mediated angiogenesis could be an active mechanism for the obesity-associated vascular rarefaction in AT, and thus Nrg4 is an attracting pharmacotherapeutic target in the prevention and/or treatment of obesity-related metabolic disorders.

Incidence of nonalcoholic steatohepatitis (NASH), which is considered a hepatic manifestation of metabolic syndrome, has been increasing worldwide with the rise in obesity; however, its pathological mechanism is poorly understood. Here, we demonstrate that the hepatic expression of aortic carboxypeptidase–like protein (ACLP), a glycosylated, secreted protein, increases in NASH in humans and mice. Furthermore, we elucidate that ACLP is a ligand, unrelated to WNT proteins, that activates the canonical WNT pathway and exacerbates NASH pathology. In the liver, ACLP is specifically expressed in hepatic stellate cells (HSCs). As fatty liver disease progresses, ACLP expression is enhanced via activation of STAT3 signaling by obesity-related factors in serum. ACLP specifically binds to frizzled-8 and low-density lipoprotein–related receptor 6 to form a ternary complex that activates canonical WNT signaling. Consequently, ACLP activates HSCs by inhibiting PPARγ signals. HSC-specific ACLP deficiency inhibits fibrosis progression in NASH by inhibiting canonical WNT signaling in HSCs. The present study elucidates the role of canonical WNT pathway activation by ACLP in NASH pathology, indicating that NASH can be treated by targeting ACLP-induced canonical WNT pathway activation in HSCs.

The tumor microenvironment promotes epigenetic changes in tumor cells associated with tumor aggressiveness. Here we report that in primary tumor cells, increased interleukin-6 (IL-6) expression brought on by DNA demethylation of its promoter by ten-eleven translocation 2 (TET2) promotes lung metastasis in osteosarcoma (OS). Xenograft experiments show increased IL-6 expression and decreased methylation of its promoter in OS cells after implantation relative to before implantation. In addition, changes in IL-6 methylation and expression seen in OS cells at the primary site were maintained at the metastatic site. TET2 knockdown in OS cells suppressed upregulation of IL-6 and demethylation of its promoter in xenograft tumors and decreased tumor metastasis. We also present evidence showing that tumor cell-derived IL-6 facilitates glycolytic metabolism in tumor cells by activating the MEK/ERK1/2/hypoxia-inducible transcription factor-1α (HIF-1α) pathway and increases lung colonization by OS cells by upregulating expression of intercellular adhesion molecule-1 (ICAM-1), enhancing tumor metastasis. Blocking IL-6 signaling with a humanized monoclonal antibody against the IL-6 receptor reduced lung metastasis and prolonged survival of xenografted mice. These findings suggest that TET2-dependent IL-6 induction enables acquisition of aggressive phenotypes in OS cells via the tumor microenvironment and that blocking IL-6 signaling could be serve as a potential therapy to antagonize metastasis.

Skeletal muscle atrophy, or sarcopenia, is commonly observed in older individuals and in those with chronic disease and is associated with decreased quality of life. There is recent medical and broad concern that sarcopenia is rapidly increasing worldwide as populations age. At present, strength training is the only effective intervention for preventing sarcopenia development, but it is not known how this exercise regimen counteracts this condition. Here, we report that expression of the inflammatory mediator angiopoietin-like protein 2 (ANGPTL2) increases in skeletal muscle of aging mice. Moreover, in addition to exhibiting increased inflammation and accumulation of reactive oxygen species (ROS), denervated atrophic skeletal muscles in a mouse model of denervation-induced muscle atrophy had increased ANGPTL2 expression. Interestingly, mice with a skeletal myocyte–specific Angptl2 knockout had attenuated inflammation and ROS accumulation in denervated skeletal muscle, accompanied by increased satellite cell activity and inhibition of muscular atrophy compared with mice harboring wildtype Angptl2. Moreover, consistent with these phenotypes, wildtype mice undergoing exercise training displayed decreased ANGPTL2 expression in skeletal muscle. In conclusion, ANGPTL2 up-regulation in skeletal myocytes accelerates muscle atrophy, and exercise-induced attenuation of ANGPTL2 expression in those tissues may partially explain how exercise training prevents sarcopenia.

Adipose tissue dysfunction is causally implicated in the impaired metabolic homeostasis associated with obesity; however, detailed mechanisms underlying dysregulated adipocyte functions in obesity remain to be elucidated. Here we searched for genes that provide a previously unknown mechanism in adipocyte metabolic functions and identified family with sequence similarity 13, member A (Fam13a) as a factor that modifies insulin signal cascade in adipocytes. Fam13a was highly expressed in adipose tissue, predominantly in mature adipocytes, and its expression was substantially reduced in adipose tissues of obese compared with lean mice. We revealed that Fam13a accentuated insulin signaling by recruiting protein phosphatase 2A with insulin receptor substrate 1 (IRS1), leading to protection of IRS1 from proteasomal degradation. We further demonstrated that genetic loss of Fam13a exacerbated obesity-related metabolic disorders, while targeted activation of Fam13a in adipocytes ameliorated it in association with altered adipose tissue insulin sensitivity in mice. Our data unveiled a previously unknown mechanism in the regulation of adipocyte insulin signaling by Fam13a and identified its significant role in systemic metabolic homeostasis, shedding light on Fam13a as a pharmacotherapeutic target to treat obesity-related metabolic disorders.

Background Bile acid binding resin (BAR) absorbs intestinal bile acids, and improves obesity and metabolic disorders, but the precise mechanism remains to be clarified. Recent findings reveal that obesity is associated with skewed intestinal microbiota. Thus, we investigated the effect of BAR on intestinal microbiota and the role of microbiota in the prevention of obesity in high-fat diet-induced obesity in mice. Procedures Male Balb/c mice were fed a low-fat diet (LFD), high-fat diet (HFD), or HFD with BAR (HFD+BAR), and then metabolic parameters, caecal microbiota, and metabolites were investigated. The same interventions were conducted in germ-free and antibiotic-treated mice. Main findings The frequency of Clostridium leptum subgroup was higher in both HFD-fed and HFD+BAR-fed mice than in LFD-fed mice. The frequency of Bacteroides-Prevotella group was lower in HFD-fed mice than in LFD-fed mice, but the frequency was higher in HFD+BAR-fed mice than in HFD-fed mice. Caecal propionate was lower in HFD-fed mice than in LFD-fed mice, and higher in HFD+BAR-fed mice than in HFD-fed mice. HFD+BAR-fed mice showed lower adiposity than HFD-fed mice, and the reduction was not observed in germ-free or antibiotic-treated mice. Colonized germ-free mice showed a reduction in adiposity by BAR administration. Energy expenditure was lower in HFD-fed mice and higher in HFD+BAR-fed mice, but the increments induced by administration of BAR were not observed in antibiotic-treated mice. Conclusions Modulation of intestinal microbiota by BAR could be a novel therapeutic approach for obesity.

Recent studies revealed that the inhibition of mitochondrial oxidative phosphorylation (OXPHOS) is coupled with the mitochondrial unfolded protein response, thereby stimulating the secretion of non-cell autonomous factors, which may control systemic energy metabolism and longevity. However, the nature and roles of non-cell autonomous factors induced in adipose tissue in response to reduced OXPHOS function remain to be clarified in mammals. CR6-interacting factor 1 (CRIF1) is an essential mitoribosomal protein for the intramitochondrial production of mtDNA-encoded OXPHOS subunits. Deficiency of CRIF1 impairs the proper formation of the OXPHOS complex, resulting in reduced function. To determine which secretory factors are induced in response to reduced mitochondrial OXPHOS function, we analyzed gene expression datasets in Crif1-depleted mouse embryonic fibroblasts. Crif1 deficiency preferentially increased the expression of angiopoietin-like 6 (Angptl6) and did not affect other members of the ANGPTL family. Moreover, treatment with mitochondrial OXPHOS inhibitors increased the expression of Angptl6 in cultured adipocytes. To confirm Angptl6 induction in vivo, we generated a murine model of reduced mitochondrial OXPHOS function using adipose tissue-specific Crif1-deficient mice and verified the upregulation of Angptl6 and fibroblast growth factor 21 (Fgf21) in white adipose tissue. Treatment with recombinant ANGPTL6 protein increased oxygen consumption and Pparα expression through the extracellular signal-regulated kinase/mitogen-activated protein kinase pathway in cultured adipocytes. Furthermore, the ANGPTL6-mediated increase in Pparα expression resulted in increased FGF21 expression, thereby promoting β-oxidation. In conclusion, mitochondrial OXPHOS function governs the expression of ANGPTL6, which is an essential factor for FGF21 production in adipose tissue and cultured adipocytes.

The intestinal epithelium continually self‐renews and can rapidly regenerate after damage. Dysregulation of intestinal epithelial homeostasis leads to severe inflammatory bowel disease. Additionally, aberrant signaling by the secreted protein angiopoietin‐like protein 2 (ANGPTL2) causes chronic inflammation in a variety of diseases. However, little is known about the physiologic role of ANGPTL2 in normal tissue homeostasis and during wound repair following injury. Here, we assessed ANGPTL2 function in intestinal physiology and disease in vivo . Although intestinal development proceeded normally in Angptl2 ‐deficient mice, expression levels of the intestinal stem cell (ISC) marker gene Lgr5 decreased, which was associated with decreased transcriptional activity of β‐catenin in Angptl2 ‐deficient mice. Epithelial regeneration after injury was significantly impaired in Angptl2 ‐deficient relative to wild‐type mice. ANGPTL2 was expressed and functioned within the mesenchymal compartment cells known as intestinal subepithelial myofibroblasts (ISEMFs). ANGPTL2 derived from ISEMFs maintained the intestinal stem cell niche by modulating levels of competing signaling between bone morphogenetic protein (BMP) and β‐catenin. These results support the importance of ANGPTL2 in the stem cell niche in regulating stemness and epithelial wound healing in the intestine.

Sarcopenia due to loss of skeletal muscle mass and strength leads to physical inactivity and decreased quality of life. The number of individuals with sarcopenia is rapidly increasing as the number of older people increases worldwide, making this condition a medical and social problem. Some patients with sarcopenia exhibit accumulation of peri-muscular adipose tissue (PMAT) as ectopic fat deposition surrounding atrophied muscle. However, an association of PMAT with muscle atrophy has not been demonstrated. Here, we show that PMAT is associated with muscle atrophy in aged mice and that atrophy severity increases in parallel with cumulative doses of PMAT. We observed severe muscle atrophy in two different obese model mice harboring significant PMAT relative to respective control non-obese mice. We also report that denervation-induced muscle atrophy was accelerated in non-obese young mice transplanted around skeletal muscle with obese adipose tissue relative to controls transplanted with non-obese adipose tissue. Notably, transplantation of obese adipose tissue into peri-muscular regions increased nuclear translocation of FoxO transcription factors and upregulated expression FoxO targets associated with proteolysis (Atrogin1 and MuRF1) and cellular senescence (p19 and p21) in muscle. Conversely, in obese mice, PMAT removal attenuated denervation-induced muscle atrophy and suppressed upregulation of genes related to proteolysis and cellular senescence in muscle. We conclude that PMAT accumulation accelerates age- and obesity-induced muscle atrophy by increasing proteolysis and cellular senescence in muscle.

Choroidal neovascularization (CNV) is a pathogenic process of age-related macular degeneration, a vision-threatening disease. The retinal pigment epithelium and macrophages both influence CNV development. However, the underlying mechanisms remain obscure. Here, we focus on Angptl2 (angiopoietin-like protein 2), a cytokine involved in age-related systemic diseases. Angptl2 was originally identified as an adipocytokine and is also expressed in the eye. Using a laser-induced CNV model, we found that Angptl2 KO mice exhibited suppressed CNV development with reduced macrophage recruitment and inflammatory mediator induction. The mediators monocyte chemotactic protein-1, interleukin-1β (Il-1β), Il-6, matrix metalloprotease-9 (Mmp-9), and transforming growth factor-β1 (Tgf-β1) that were up-regulated during CNV development were all suppressed in the retinal pigment epithelium-choroid of CNV models generated in the Angptl2 KO mice. Bone marrow transplantation using wild-type and KO mice suggested that both bone marrow-derived and host-derived Angptl2 were responsible for macrophage recruitment and CNV development. Peritoneal macrophages derived from Angptl2 KO mice expressed lower levels of the inflammatory mediators. In the wild-type peritoneal macrophages and RAW264.7 cells, Angptl2 induced the mediators via integrins α4 and β2, followed by the downstream activation of NF-κB and ERK. The activation of NF-κB and ERK by Angptl2 also promoted macrophage migration. Therefore, Angptl2 from focal tissue might trigger macrophage recruitment, and that from recruited macrophages might promote expression of inflammatory mediators including Angptl2 in an autocrine and/or paracrine fashion to facilitate CNV development. Angptl2 might therefore represent a multistep regulator of CNV pathogenesis and serve as a new therapeutic target for age-related macular degeneration.

Lymphedema is a debilitating progressive condition that severely restricts quality of life and is frequently observed after cancer surgery. The mechanism underlying lymphedema development remains poorly understood, and no effective pharmacological means to prevent or alleviate the ailment is currently available. Using a mouse model of lymphedema, we show here that excessive generation of immature lymphatic vessels is essential for initial edema development and that this early process is also important for later development of lymphedema pathology. We found that CD4 + T cells interact with macrophages to promote lymphangiogenesis, and that both lymphangiogenesis and edema were greatly reduced in macrophage-depleted mice, lymphocyte-deficient Rag2 −/− mice or CD4 + T-cell–deficient mice. Mechanistically, T helper type 1 and T helper type 17 cells activate lesional macrophages to produce vascular endothelial growth factor-C, which promotes lymphangiogenesis, and inhibition of this mechanism suppressed not only early lymphangiogenesis, but also later development of lymphedema. Finally, we show that atorvastatin suppresses excessive lymphangiogenesis and lymphedema by inhibiting T helper type 1 and T helper type 17 cell activation. These results demonstrate that the interaction between CD4 + T cells and macrophages is a potential therapeutic target for prevention of lymphedema after surgery.

8-Nitroguanosine 3',5'-cyclic monophosphate (8-nitro-cGMP) is a nitrated derivative of guanosine 3',5'-cyclic monophosphate (cGMP) formed endogenously under conditions associated with production of both reactive oxygen species and nitric oxide. It acts as an electrophilic second messenger in the regulation of cellular signaling by inducing a post-translational modification of redox-sensitive protein thiols via covalent adduction of cGMP moieties to protein thiols (protein S-guanylation). Here, we demonstrate that 8-nitro-cGMP potentially S-guanylates thiol groups of cGMP-dependent protein kinase (PKG), the enzyme that serves as one of the major receptor proteins for intracellular cGMP and controls a variety of cellular responses. S-Guanylation of PKG was found to occur in a site specific manner; Cys42 and Cys195 were the susceptible residues among 11 Cys residues. Importantly, S-guanylation at Cys195, which is located in the high-affinity cGMP binding domain of PKG, causes persistent enzyme activation as determined by in vitro kinase assay as well as by an organ bath assay. In vivo, S-guanylation of PKG was demonstrated to occur in mice without any specific treatment and was significantly enhanced by lipopolysaccharide administration. These findings warrant further investigation in terms of the physiological and pathophysiological roles of S-guanylation-dependent persistent PKG activation.

Background The rapid increase in the number of heart failure (HF) patients in parallel with the increase in the number of older people is receiving attention worldwide. HF not only increases mortality but decreases quality of life, creating medical and social problems. Thus, it is necessary to define molecular mechanisms underlying HF development and progression. HMGB2 is a member of the high-mobility group superfamily characterized as nuclear proteins that bind DNA to stabilize nucleosomes and promote transcription. A recent in vitro study revealed that HMGB2 loss in cardiomyocytes causes hypertrophy and increases HF-associated gene expression. However, it's in vivo function in the heart has not been assessed. Methods and Results: Western blotting analysis revealed increased HMGB2 expression in heart tissues undergoing pressure overload by transverse aorta constriction (TAC) in mice. Hmgb2 homozygous knockout (Hmgb2-/-) mice showed cardiac dysfunction due to AKT inactivation and decreased sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA)2a activity. Compared to wild-type mice, Hmgb2-/- mice had worsened cardiac dysfunction after TAC surgery, predisposing mice to HF development and progression. Conclusions This study demonstrates that upregulation of cardiac HMGB2 is an adaptive response to cardiac stress, and that loss of this response could accelerate cardiac dysfunction, suggesting that HMGB2 plays a cardioprotective role.

SP7/Osterix (OSX) is a master regulatory transcription factor that activates a variety of genes during differentiation of osteoblasts. However, the influence of post-translational modifications on the regulation of its transactivation activity is largely unknown. Here, we report that sirtuins, which are NAD(+)-dependent deacylases, regulate lysine deacylation-mediated transactivation of OSX. Germline Sirt7 knockout mice develop severe osteopenia characterized by decreased bone formation and an increase of osteoclasts. Similarly, osteoblast-specific Sirt7 knockout mice showed attenuated bone formation. Interaction of SIRT7 with OSX leads to the activation of transactivation by OSX without altering its protein expression. Deacylation of lysine (K) 368 in the C-terminal region of OSX by SIRT7 promote its N-terminal transactivation activity. In addition, SIRT7-mediated deacylation of K368 also facilitates depropionylation of OSX by SIRT1, thereby increasing OSX transactivation activity. In conclusion, our findings suggest that SIRT7 has a critical role in bone formation by regulating acylation of OSX., SP7/Osterix is a transcription factor involved in osteoblast differentiation. Here, the authors show that Sirtuin 7 activates Osterix posttranslationally by regulating its lysine acylation, and that mice lacking Sirtuin 7 in osteoblasts show reduced bone formation.

Background Recently, it was reported that angiopoietin-like protein 2 (ANGPTL2) secreted from a pathologically stressed heart accelerates cardiac dysfunction in an autocrine/paracrine manner, and that suppression of ANGPTL2 production in the heart restored cardiac function and myocardial energy metabolism, thereby blocking heart failure (HF) development. Interestingly, circulating ANGPTL2 concentrations reportedly increase in HF patients, suggesting a possible endocrine effect on cardiac dysfunction. However, it remains unclear why circulating ANGPTL2 increases in those subjects and whether circulating ANGPTL2 alters cardiac function in an endocrine manner.Methods and Results:It was found that circulating ANGPTL2 levels are positively correlated with left atrial diameter and pulmonary capillary wedge pressure, and are inversely proportional to the percent of ejection fraction in patients with dilated cardiomyopathy. Furthermore, in mice, circulating ANGPTL2 concentrations increased as HF developed following transverse aorta constriction (TAC), and were inversely correlated with the percent of fractional shortening. Interestingly, although circulating ANGPTL2 concentrations significantly increased in transgenic mice overexpressing keratinocyte-derived ANGPTL2, no pathological cardiac remodeling was seen. Furthermore, it was observed that there was no difference in HF development between transgenic mice and controls following TAC surgery. Conclusions Circulating ANGPTL2 levels increase in subjects experiencing cardiac dysfunction. However, circulating ANGPTL2 does not promote cardiac dysfunction in an endocrine manner, and increased levels of circulating ANGPTL2 seen during HF are a secondary effect of increased ANGPTL2 secretion from stressed hearts in HF pathologies.

The gene encoding the chromatin remodeler CHD8 is the most frequently mutated gene in individuals with autism spectrum disorder (ASD). Heterozygous mutations in CHD8 give rise to ASD that is often accompanied by macrocephaly, gastrointestinal complaints, and slender habitus. Whereas most phenotypes of CHD8 haploinsufficiency likely result from delayed neurodevelopment, the mechanism underlying slender habitus has remained unknown. Here, we show that CHD8 interacts with CCAAT/enhancer-binding protein β (C/EBPβ) and promotes its transactivation activity during adipocyte differentiation. Adipogenesis was impaired in Chd8-deleted preadipocytes, with the upregulation of C/EBPα and peroxisome-proliferator-activated receptor γ (PPARγ), two master regulators of this process, being attenuated in mutant cells. Furthermore, mice with CHD8 ablation in white preadipocytes had a markedly reduced white adipose tissue mass. Our findings reveal a mode of C/EBPβ regulation by CHD8 during adipogenesis, with CHD8 deficiency resulting in a defect in the development of white adipose tissue.

Introduction Breast cancer is a leading cause of cancer-related death in women worldwide, and its metastasis is a major cause of disease mortality. Therefore, identification of the mechanisms underlying breast cancer metastasis is crucial for the development of therapeutic and diagnostic strategies. Our recent study of immunodeficient female mice transplanted with MDA-MB231 breast cancer cells demonstrated that tumor cell-derived angiopoietin-like protein 2 (ANGPTL2) accelerates metastasis through both increasing tumor cell migration in an autocrine/paracrine manner, and enhancing tumor angiogenesis. To determine whether ANGPTL2 contributes to its clinical pathogenesis, we asked whether serum ANGPTL2 levels reflect the clinical features of breast cancer progression. Methods We monitored the levels of secreted ANGPTL2 in supernatants of cultured proliferating MDA-MB231 cells. We also determined whether the circulating ANGPTL2 levels were positively correlated with cancer progression in an in vivo breast cancer xenograft model using MDA-MB231 cells. Finally, we investigated whether serum ANGPTL2 levels were associated with clinical features in breast cancer patients. Results Both in vitro and in vivo experiments showed that the levels of ANGPTL2 secreted from breast cancer cells increased with cell proliferation and cancer progression. Serum ANGPTL2 levels in patients with metastatic breast cancer were significantly higher than those in healthy subjects or in patients with ductal carcinoma in situ or non-metastatic invasive ductal carcinoma. Serum ANGPTL2 levels in patients negative for estrogen receptors and progesterone receptors, particularly triple-negative cases, reflected histological grades. Conclusions These findings suggest that serum ANGPTL2 levels in breast cancer patients could represent a potential marker of breast cancer metastasis.

Metabolic disorders including obesity and insulin resistance have their basis in dysregulated lipid metabolism and low-grade inflammation. In a microarray search of unique lipase-related genes whose expressions are associated with obesity, we found that two secreted phospholipase A2s (sPLA2s), PLA2G5 and PLA2G2E, were robustly induced in adipocytes of obese mice. Analyses of Pla2g5−/− and Pla2g2e−/− mice revealed distinct and previously unrecognized roles of these sPLA2s in diet-induced obesity. PLA2G5 hydrolyzed phosphatidylcholine in fat-overladen low-density lipoprotein to release unsaturated fatty acids, which prevented palmitate-induced M1 macrophage polarization. As such, PLA2G5 tipped the immune balance toward an M2 state, thereby counteracting adipose tissue inflammation, insulin resistance, hyperlipidemia and obesiy. PLA2G2E altered minor lipoprotein phospholipids, phosphatidylserine and phosphatidylethanolamine, and moderately facilitated lipid accumulation in adipose tissue and liver. Collectively, the identification of “metabolic sPLA2s” adds this gene family to a growing list of lipolytic enzymes that act as metabolic coordinators.

Objective— Cardiovascular disease (CVD), the most common morbidity resulting from atherosclerosis, remains a frequent cause of death. Efforts to develop effective therapeutic strategies have focused on vascular inflammation as a critical pathology driving atherosclerosis progression. Nonetheless, molecular mechanisms underlying this activity remain unclear. Here, we ask whether angiopoietin-like protein 2 (Angptl2), a proinflammatory protein, contributes to vascular inflammation that promotes atherosclerosis progression. Approach and Results— Histological analysis revealed abundant Angptl2 expression in endothelial cells and macrophages infiltrating atheromatous plaques in patients with cardiovascular disease. Angptl2 knockout in apolipoprotein E–deficient mice ( ApoE −/− / Angptl2 −/− ) attenuated atherosclerosis progression by decreasing the number of macrophages infiltrating atheromatous plaques, reducing vascular inflammation. Bone marrow transplantation experiments showed that Angptl2 deficiency in endothelial cells attenuated atherosclerosis development. Conversely, ApoE −/− mice crossed with transgenic mice expressing Angptl2 driven by the Tie2 promoter ( ApoE −/− /Tie2- Angptl2 Tg), which drives Angptl2 expression in endothelial cells but not monocytes/macrophages, showed accelerated plaque formation and vascular inflammation because of increased numbers of infiltrated macrophages in atheromatous plaques. Tie2- Angptl2 Tg mice alone did not develop plaques but exhibited endothelium-dependent vasodilatory dysfunction, likely because of decreased production of endothelial cell–derived nitric oxide. Conversely, Angptl2 −/− mice exhibited less severe endothelial dysfunction than did wild-type mice when fed a high-fat diet. In vitro, Angptl2 activated proinflammatory nuclear factor-κB signaling in endothelial cells and increased monocyte/macrophage chemotaxis. Conclusions— Endothelial cell–derived Angptl2 accelerates vascular inflammation by activating proinflammatory signaling in endothelial cells and increasing macrophage infiltration, leading to endothelial dysfunction and atherosclerosis progression.

Chronic inflammation has received much attention as a risk factor for carcinogenesis. We recently reported that Angiopoietin-like protein 2 (Angptl2) facilitates inflammatory carcinogenesis and metastasis in a chemically induced squamous cell carcinoma (SCC) of the skin mouse model. In particular, we demonstrated that Angptl2-induced inflammation enhanced susceptibility of skin tissues to “preneoplastic change” and “malignant conversion” in SCC development; however, mechanisms underlying this activity remain unclear. Using this model, we now report that transgenic mice overexpressing Angptl2 in skin epithelial cells (K14- Angptl2 Tg mice) show enhanced oxidative stress in these tissues. Conversely, in the context of this model, Angptl2 knockout (KO) mice show significantly decreased oxidative stress in skin tissue as well as a lower incidence of SCC compared with wild-type mice. In the chemically induced SCC model, treatment of K14- Angptl2 Tg mice with the antioxidant N -acetyl cysteine (NAC) significantly reduced oxidative stress in skin tissue and the frequency of SCC development. Interestingly, K14- Angptl2 Tg mice in the model also showed significantly decreased expression of mRNA encoding the DNA mismatch repair enzyme Msh2 compared with wild-type mice and increased methylation of the Msh2 promoter in skin tissues. Msh2 expression in skin tissues of Tg mice was significantly increased by NAC treatment, as was Msh2 promoter demethylation. Overall, this study strongly suggests that the inflammatory mediator Angptl2 accelerates chemically induced carcinogenesis through increased oxidative stress and decreased Msh2 expression in skin tissue. Implications: Angptl2-induced inflammation increases susceptibility to microenvironmental changes, allowing increased oxidative stress and decreased Msh2 expression; therefore, Angptl2 might be a target to develop new strategies to antagonize these activities in premalignant tissue. Mol Cancer Res; 12(2); 239–49. ©2013 AACR . This article is featured in Highlights of This Issue, [p. 165][1] [1]: /lookup/volpage/12/165?iss=2

Macrophages play crucial roles in combatting infectious disease by promoting inflammation and phagocytosis. Angiopoietin-like protein 2 (ANGPTL2) is a secreted factor that induces tissue inflammation by attracting and activating macrophages to produce inflammatory cytokines in chronic inflammation-associated diseases such as obesity-associated metabolic syndrome, atherosclerosis, and rheumatoid arthritis. Here, we asked whether and how ANGPTL2 activates macrophages in the innate immune response. ANGPTL2 was predominantly expressed in proinflammatory mouse bone marrow-derived differentiated macrophages (GM-BMMs) following GM-CSF treatment relative to anti-inflammatory cells (M-BMMs) established by M-CSF treatment. Expression of the proinflammatory markers IL-1β, IL-12p35, and IL-12p40 significantly decreased in GM-BMMs from Angptl2-deficient compared with wild-type (WT) mice, suggestive of attenuated proinflammatory activity. We also report that ANGPTL2 inflammatory signaling is transduced through integrin α5β1 rather than through paired immunoglobulin-like receptor B. Interestingly, Angptl2-deficient mice were more susceptible to infection with Salmonella enterica serovar Typhimurium than were WT mice. Moreover, nitric oxide (NO) production by Angptl2-deficient GM-BMMs was significantly lower than in WT GM-BMMs. Collectively, our findings suggest that macrophage-derived ANGPTL2 promotes an innate immune response in those cells by enhancing proinflammatory activity and NO production required to fight infection.

Ischemic stroke is a leading cause of death and disability worldwide. Several reports suggest that acute inflammation after ischemia-reperfusion exacerbates brain damage; however, molecular mechanisms underlying this effect remain unclear. Here, we report that MAC-3-positive immune cells, including infiltrating bone marrow-derived macrophages and activated microglia, express abundant angiopoietin-like protein (ANGPTL) 2 in ischemic mouse brain in a transient middle cerebral artery occlusion (MCAO) model. Both neurological deficits and infarct volume decreased in transient MCAO model mice established in Angptl2 knockout (KO) relative to wild-type mice. Acute brain inflammation after ischemia-reperfusion, as estimated by expression levels of pro-inflammatory cytokines such as interleukin (IL)-1β and tumor necrosis factor alpha (TNF)-α, was significantly suppressed in Angptl2 KO compared to control mice. Moreover, analysis employing bone marrow chimeric models using Angptl2 KO and wild-type mice revealed that infiltrated bone marrow-derived macrophages secreting ANGPTL2 significantly contribute to acute brain injury seen after ischemia-reperfusion. These studies demonstrate that infiltrating bone marrow-derived macrophages promote inflammation and injury in affected brain areas after ischemia-reperfusion, likely via ANGPTL2 secretion in the acute phase of ischemic stroke.

Angiopoietin-like protein 2 (ANGPTL2) is a chronic inflammatory mediator that, when deregulated, is associated with various pathologies. However, little is known about its activity in lung. To assess a possible lung function, we generated a rabbit monoclonal antibody that specifically recognizes mouse ANGPTL2 and then evaluated protein expression in mouse lung tissue. We observed abundant ANGPTL2 expression in both alveolar epithelial type I and type II cells and in resident alveolar macrophages under normal conditions. To assess ANGPTL2 function, we compared lung phenotypes in Angptl2 knockout (KO) and wild-type mice but observed no overt changes. We then generated a bleomycin-induced interstitial pneumonia model using wild-type and Angptl2 KO mice. Bleomycin-treated wild-type mice showed specifically upregulated ANGPTL2 expression in areas of severe fibrosing interstitial pneumonia, while Angptl2 KO mice developed more severe lung fibrosis than did comparably treated wild-type mice. Lung fibrosis seen following bone marrow transplant was comparable in wild-type or Angptl2 KO mice treated with bleomycin, suggesting that Angptl2 loss in myeloid cells does not underlie fibrotic phenotypes. We conclude that Angptl2 deficiency in lung epithelial cells and resident alveolar macrophages causes severe lung fibrosis seen following bleomycin treatment, suggesting that ANGPTL2 derived from these cell types plays a protective role against fibrosis in lung.

Strategies to inhibit metastasis have been mainly unsuccessful in part due to insufficient mechanistic understanding. Here, we report evidence of critical role for the angiopoietin-like protein 2 (ANGPTL2) in metastatic progression. In mice, Angptl2 has been implicated in inflammatory carcinogenesis but it has not been studied in human tumors. In patients with lung cancer, elevated levels of ANGPTL2 expression in tumor cells within the primary tumor were associated with a reduction in the period of disease-free survival after surgical resection. Transcription factors NFATc, ATF2, and c-Jun upregulated in aggressive tumor cells promoted increased Angptl2 expression. Most notably, tumor cell–derived ANGPTL2 increased in vitro motility and invasion in an autocrine/paracrine manner, conferring an aggressive metastatic tumor phenotype. In xenograft mouse models, tumor cell–derived ANGPTL2 accelerated metastasis and shortened survival whereas attenuating ANGPTL2 expression in tumor cells–blunted metastasis and extended survival. Overall, our findings showed that tumor cell–derived ANGPTL2 drives metastasis and provided an initial proof of concept for blockade of its action as a strategy to antagonize the metastatic process. Cancer Res; 72(7); 1784–94. ©2012 AACR.

Genome-wide association studies (GWAS) have identified genetic variants contributing to the risk of cardiovascular disease (CVD) at the chromosome 9p21 locus. The CVD-associated region is adjacent to the two cyclin dependent kinase inhibitors (CDKN)2A and 2B and the last exons of the non-coding RNA, ANRIL. It is still not clear which of or how these transcripts are involved in the pathogenesis of atherosclerosis.We assessed the hypothesis that 9p21 locus polymorphisms influence the expression of the transcripts in the region (ANRIL, CDKN2A/B) and that these transcripts contribute to atherogenesis through the modulation of proliferation in VSMC.We genotyped 18 SNPs (r(2)0.8 and MAF0.05) across the region of interest: CDKN2A/B and ANRIL, encompassing the CVD-associated region. RNA and DNA were extracted from the blood of 57 volunteers (69-72 years old). Carotid ultrasound was performed in 56 subjects. CDKN2A/B and ANRIL (exons 1-2 and 17-18) expression was measured employing RT-PCR. Gene expression and cell growth were evaluated in cultured VSMC after the siRNA-mediated knock-down of ANRIL.The risk alleles for atherosclerosis-related phenotypes were consistently associated with a lower expression of ANRIL when evaluating exons 1-2. Common carotid artery stenosis was associated with a significantly lower (P0.01) expression of ANRIL (exons 1-2). ANRIL knock-down in VSMC caused significant variation in expression of CDKN2A/B (P0.05) and reduction of cell growth (P0.05) in vitro.Disease-associated SNPs at the 9p21 locus predominantly affect the expression of ANRIL. Overall, our results suggest that several CVD-associated SNPs in the 9p21 locus affect the expression of ANRIL, which, in turn modulate cell growth, possibly via CDKN2A/B regulation.

Nifedipine, an L-type calcium (Ca) channel blocker, is one of the most widely used Ca channel-blocking medications for hypertension. Previous studies have reported an association of nifedipine hypertensive treatment with decreased body weight in obese hypertensive humans and rat models. However, the precise mechanism underlying how nifedipine functions metabolically has not been elucidated. Here, we investigated the long-term effect of a non-hypotensive nifedipine dose using a mildly obese, endothelial NO synthase-deficient mouse model. Treating these mice with nifedipine decreased their body weight gain ratio, and white adipose tissue weight compared with the untreated controls. Metabolic analyses indicated that nifedipine treatment upregulated whole-body energy expenditure through increasing oxygen consumption and reducing the respiratory exchange ratio, suggesting that nifedipine promotes lipid oxidation rather than carbohydrate utilization. Furthermore, nifedipine treatment upregulated the expression of the peroxisome proliferator-activated receptor-γ coactivator -1α (PGC-1α) in skeletal muscle. Overall, these results suggest that a non-hypotensive dose of nifedipine has pleiotropic effects on energy expenditure that could ameliorate obesity.

Objective— To investigate whether and how the endoplasmic reticulum (ER) stress–induced, CCAAT/enhancer-binding protein-homologous protein (CHOP)-mediated pathway regulates myocardial ischemia/reperfusion injury. Methods and Results— Wild-type and chop -deficient mice underwent 50 minutes of left coronary artery occlusion followed by reperfusion. Expression of chop and spliced x-box binding protein- 1 ( sxbp1 ) mRNA was rapidly and significantly increased in reperfused myocardium of wild-type mice. chop -deficient mice exhibited markedly reduced injury size after reperfusion compared with wild-type mice, accompanied by a decreasing number of terminal deoxynucleotidyl transferase dUTP nick-end labeling–positive cardiomyocytes. Interestingly, myocardial inflammation, as assessed by expression of inflammatory cytokines and chemokines and numbers of infiltrated inflammatory cells, was also attenuated in chop -deficient mice. Moreover, expression of interleukin-6 mRNA in response to lipopolysaccharide was enhanced by simultaneous stimulation with thapsigargin, a potent ER stressor, in wild-type cardiomyocytes but not in chop -deficient cardiomyocytes. Finally, we found that superoxide was produced in reperfused myocardium and that intravenous administration of edaravone, a free radical scavenger, immediately before reperfusion significantly suppressed the superoxide overproduction and subsequent expression of sxbp1 and chop mRNA, followed by reduced injury size in wild-type mice. Conclusion— The ER stress–induced, CHOP-mediated pathway, which is activated in part by superoxide overproduction after reperfusion, exacerbates myocardial ischemia/reperfusion injury by inducing cardiomyocyte apoptosis and myocardial inflammation.

Masato Yano, Ken Watanabe, Tadashi Yamamoto, Kazutaka Ikeda, Takafumi Senokuchi, Meihong Lu, Tsuyoshi Kadomatsu, Hiroto Tsukano, Masahito Ikawa, Masaru Okabe, Shohei Yamaoka, Toshiro Okazaki, Hisanori Umehara, Tomomi Gotoh, Wen-Jie Song, Koichi Node, Ryo Taguchi, Kazuya Yamagata, Yuichi Oike, Mitochondrial Dysfunction and Increased Reactive Oxygen Species Impair Insulin Secretion in Sphingomyelin Synthase 1-null Mice, Journal of Biological Chemistry, Volume 286, Issue 5, 2011, Pages 3992-4002, ISSN 0021-9258, https://doi.org/10.1074/jbc.M110.179176., Sphingomyelin synthase 1 (SMS1) catalyzes the conversion of ceramide to sphingomyelin. Here, we generated and analyzed SMS1-null mice. SMS1-null mice exhibited moderate neonatal lethality, reduced body weight, and loss of fat tissues mass, suggesting that they might have metabolic abnormality. Indeed, analysis on glucose metabolism revealed that they showed severe deficiencies in insulin secretion. Isolated mutant islets exhibited severely impaired ability to release insulin, dependent on glucose stimuli. Further analysis indicated that mitochondria in mutant islet cells cannot up-regulate ATP production in response to glucose. We also observed additional mitochondrial abnormalities, such as hyperpolarized membrane potential and increased levels of reactive oxygen species (ROS) in mutant islets. Finally, when SMS1-null mice were treated with the anti-oxidant N-acetyl cysteine, we observed partial recovery of insulin secretion, indicating that ROS overproduction underlies pancreatic β-cell dysfunction in SMS1-null mice. Altogether, our data suggest that SMS1 is important for controlling ROS generation, and that SMS1 is required for normal mitochondrial function and insulin secretion in pancreatic β-cells.

E3 ubiquitin ligase complexes of the SCF type consist of ring-box 1 (Rbx1), cullin 1 (Cul1), S-phase kinase-associated protein 1 (Skp1), and a member of the F-box family of proteins. The identity of the F-box protein determines the substrate specificity of the complex. The F-box family member F-box– and WD repeat domain–containing 7 (Fbxw7; also known as Fbw7, SEL-10, hCdc4, and hAgo) targets for degradation proteins with wide-ranging functions, and uncovering its in vivo role has been difficult, because Fbxw7–/– embryos die in utero. Using two different Cre-loxP systems (Mx1-Cre and Alb-Cre), we generated mice with liver-specific null mutations of Fbxw7. Hepatic ablation of Fbxw7 resulted in hepatomegaly and steatohepatitis, with massive deposition of triglyceride, a phenotype similar to that observed in humans with nonalcoholic steatohepatitis. Both cell proliferation and the abundance of Fbxw7 substrates were increased in the Fbxw7-deficient liver. Long-term Fbxw7 deficiency resulted in marked proliferation of the biliary system and the development of hamartomas. Fbxw7 deficiency also skewed the differentiation of liver stem cells toward the cholangiocyte lineage rather than the hepatocyte lineage in vitro. This bias was corrected by additional loss of the Notch cofactor RBP-J, suggesting that Notch accumulation triggered the abnormal proliferation of the biliary system. Together, our results suggest that Fbxw7 plays key roles, regulating lipogenesis and cell proliferation and differentiation in the liver.

Macrophages infiltrate adipose tissue in obesity and are involved in the induction of inflammation, thereby contributing to the development of obesity-associated metabolic disorders. Here, we show that the macrophage-derived soluble protein AIM is endocytosed into adipocytes via CD36. Within adipocytes, AIM associates with cytosolic fatty acid synthase (FAS), thereby decreasing FAS activity. This decreases lipid droplet size, stimulating the efflux of free fatty acids and glycerol from adipocytes. As an additional consequence of FAS inhibition, AIM prevents preadipocyte maturation. In vivo, the increase in adipocyte size and fat weight induced by high-fat diet (HFD) was accelerated in AIM-deficient (AIM(-)(/-)) mice compared to AIM(+/+) mice. Moreover, injection of recombinant AIM in AIM(-)(/-) mice suppresses the increase in fat mass induced by HFD. Interestingly, metabolic rates are comparable in AIM(-)(/-) and AIM(+/+) mice, suggesting that AIM specifically influences adipocyte status. Thus, this AIM function in adipocytes may be physiologically relevant to obesity progression.

Purpose: The biological effect of interleukin-6 (IL-6) signaling in oral squamous cell carcinoma (OSCC) and whether IL-6 receptor (IL-6R)-mediated signaling can be a therapeutic target for OSCC are unclear. The aim of this study was to investigate the effects of inhibition of IL-6R–mediated signaling on OSCC progression and to evaluate the availability of tocilizumab, a humanized antihuman IL-6R antibody, as a therapeutic agent for OSCC. Experimental Design: We evaluated expression levels of IL-6 and IL-6R in 58 OSCC tissues and 4 OSCC cell lines by real-time quantitative reverse transcription-PCR and/or immunohistochemstry. We investigated the effects of tocilizumab on OSCC growth in vitro and in xenografts. Xenografts were analyzed by immunohistochemistry for phosphorylated signal transducer and activator of transcription 3 (pSTAT3), Ki-67, and CD31, and terminal deoxynucleotidyl transferase–mediated dUTP nick end labeling assay was done. Results: Expression levels of IL-6 at both mRNA and protein levels in OSCC tissues were significantly higher than those in normal mucosal tissues. In addition, OSCC cell lines expressed higher levels of both IL-6 and IL-6R mRNA than did HaCaT keratinocytes. Tocilizumab significantly reduced in vivo growth of SAS cells with a drastic reduction of STAT3 phosphorylation in tumor cells in mice. Inhibition of IL-6 signaling significantly decreased vascular endothelial growth factor mRNA expression in SAS, and microvessel density and vessel diameter in SAS tumors in tocilizumab-treated mice. Conclusions: Therapeutic approaches targeting IL-6R by tocilizumab may be effective for OSCC treatment by at least inhibiting angiogenesis. (Clin Cancer Res 2009;15(17):5426–34)

A role for cell senescence and p53 in the development of insulin resistance (or prediabetes) has been obscure. Issei Komuro and colleagues now show that premature cell senescence occurs in the adipose tissue of obese mice and humans and that genetic deficiency of p53 is sufficient to prevent insulin resistance in mouse models of obesity, suggesting a new target to treat diabetes. Various stimuli, such as telomere dysfunction and oxidative stress, can induce irreversible cell growth arrest, which is termed 'cellular senescence'1,2. This response is controlled by tumor suppressor proteins such as p53 and pRb. There is also evidence that senescent cells promote changes related to aging or age-related diseases3,4,5,6. Here we show that p53 expression in adipose tissue is crucially involved in the development of insulin resistance, which underlies age-related cardiovascular and metabolic disorders. We found that excessive calorie intake led to the accumulation of oxidative stress in the adipose tissue of mice with type 2 diabetes–like disease and promoted senescence-like changes, such as increased activity of senescence-associated β-galactosidase, increased expression of p53 and increased production of proinflammatory cytokines. Inhibition of p53 activity in adipose tissue markedly ameliorated these senescence-like changes, decreased the expression of proinflammatory cytokines and improved insulin resistance in mice with type 2 diabetes–like disease. Conversely, upregulation of p53 in adipose tissue caused an inflammatory response that led to insulin resistance. Adipose tissue from individuals with diabetes also showed senescence-like features. Our results show a previously unappreciated role of adipose tissue p53 expression in the regulation of insulin resistance and suggest that cellular aging signals in adipose tissue could be a new target for the treatment of diabetes ( pages 996–967 ).

OBJECTIVE The term “receptor-associated prorenin system” (RAPS) refers to the pathogenic mechanisms whereby prorenin binding to its receptor dually activates the tissue renin-angiotensin system (RAS) and RAS-independent intracellular signaling via the receptor. The aim of the present study was to define the association of the RAPS with diabetes-induced retinal inflammation. RESEARCH DESIGN AND METHODS Long-Evans rats, C57BL/6 mice, and angiotensin II type 1 receptor (AT1-R)-deficient mice with streptozotocin-induced diabetes were treated with (pro)renin receptor blocker (PRRB). Retinal mRNA expression of prorenin and the (pro)renin receptor was examined by quantitative RT-PCR. Leukocyte adhesion to the retinal vasculature was evaluated with a concanavalin A lectin perfusion–labeling technique. Retinal protein levels of vascular endothelial growth factor (VEGF) and intercellular adhesion molecule (ICAM)-1 were examined by ELISA. Retinal extracellular signal–regulated kinase (ERK) activation was analyzed by Western blotting. RESULTS Induction of diabetes led to significant increase in retinal expression of prorenin but not the (pro)renin receptor. Retinal adherent leukocytes were significantly suppressed with PRRB. Administration of PRRB inhibited diabetes-induced retinal expression of VEGF and ICAM-1. To clarify the role of signal transduction via the (pro)renin receptor in the diabetic retina, we used AT1-R–deficient mice in which the RAS was deactivated. Retinal adherent leukocytes in AT1-R–deficient diabetic mice were significantly suppressed with PRRB. PRRB suppressed the activation of ERK and the production of VEGF, but not ICAM-1, in AT1-R–deficient diabetic mice. CONCLUSIONS These results indicate a significant contribution of the RAPS to the pathogenesis of diabetes-induced retinal inflammation, suggesting the possibility of the (pro)renin receptor as a novel molecular target for the treatment of diabetic retinopathy.

Angiopoietin-like protein family 4 (Angptl 4) has been shown to regulate lipoprotein metabolism through the inhibition of lipoprotein lipase (LPL). We generated ApoE(-/-)Angptl 4(-/-) mice to study the effect of Angptl 4 deficiency on lipid metabolism and atherosclerosis. Fasting and postolive oil-loaded triglyceride (TG) levels were largely decreased in ApoE(-/-)Angptl 4(-/-) mice compared with and ApoE(-/-)Angptl 4(+/+) mice. There was a significant (75+/-12%) reduction in atherosclerotic lesion size in ApoE(-/-)Angptl 4(-/-) mice compared with ApoE(-/-) Angptl 4(+/+) mice. Peritoneal macrophages, isolated from Angptl 4(-/-) mice to investigate the foam cell formation, showed a significant decrease in newly synthesized cholesteryl ester (CE) accumulation induced by acetyl low-density lipoprotein (acLDL) compared with those from Angptl 4(+/+) mice. Thus, genetic knockout of Angptl 4 protects ApoE(-/-) mice against development and progression of atherosclerosis and strongly suppresses the ability of the macrophages to become foam cells in vitro.

UNLABELLED It is unclear how hepatic adiponectin resistance and sensitivity mediated by the adiponectin receptor, AdipoR2, contributes to the progression of nonalcoholic steatohepatitis (NASH). The aim of this study was to examine the roles of hepatic AdipoR2 in NASH, using an animal model. We fed C57BL/6 mice a methionine-deficient and choline-deficient (MCD) diet for up to 8 weeks and analyzed changes in liver pathology caused by either an AdipoR2 short hairpin RNA-expressing adenovirus or an AdipoR2-overexpressing adenovirus. Inhibition of hepatic AdipoR2 expression aggravated the pathological state of NASH at all stages: fatty changes, inflammation, and fibrosis. In contrast, enhancement of AdipoR2 expression in the liver improved NASH at every stage, from the early stage to the progression of fibrosis. Inhibition of AdipoR2 signaling in the liver diminished hepatic peroxisome proliferator activated receptor (PPAR)-alpha signaling, with decreased expression of acyl-CoA oxidase (ACO) and catalase, leading to an increase in lipid peroxidation. Hepatic AdipoR2 overexpression had the opposite effect. Reactive oxygen species (ROS) accumulation in liver increases hepatic production of transforming growth factor (TGF)-beta1 at all stages of NASH; adiponectin/AdipoR2 signaling ameliorated TGF-beta-induced ROS accumulation in primary cultured hepatocytes, by enhancing PPAR-alpha activity and catalase expression. CONCLUSION The adiponectin resistance and sensitivity mediated by AdipoR2 in hepatocytes regulated steatohepatitis progression by changing PPAR-alpha activity and ROS accumulation, a process in which TGF-beta signaling is implicated. Thus, the liver AdipoR2 signaling pathway could be a promising target in treating NASH.

Objective— Transgenic mice overexpressing angiopoietin-related growth factor (AGF) exhibit enhanced angiogenesis, suggesting that AGF may be a useful drug target in ischemic disease. Our goal was to determine whether AGF enhances blood flow in a mouse hind-limb ischemia model and to define molecular mechanisms underlying AGF signaling in endothelial cells. Methods and Results— Intramuscular injection of adenovirus harboring AGF into the ischemic limb increased AGF production, which increased blood flow through induction of angiogenesis and arteriogenesis, thereby reducing the necessity for limb amputation. In vitro analysis showed that exposing human umbilical venous endothelial cells to AGF increased nitric oxide (NO) production through activation of an ERK1/2-endothelial NO synthetase (eNOS) signaling pathway. AGF-stimulated eNOS phosphorylation, NO production, and endothelial cell migration were all abolished by specific MEK1/2 inhibitors. Moreover, AGF did not restore blood flow to ischemic hind-limbs of either mice receiving NOS inhibitor L-NAME or eNOS knockout mice. Conclusion— Activation of an ERK1/2-eNOS-NO pathway is a crucial signaling mechanism by which AGF increases blood flow through induction of angiogenesis and arteriogenesis. Further investigation of the regulation underlying AGF signaling pathway may contribute to develop a new clinical strategy for ischemic vascular diseases.

Common molecular machineries between hematopoietic stem cell (HSC) maintenance and leukemia prevention have been highlighted. The tumor suppressor Fbxw7 (F-box and WD-40 domain protein 7), a subunit of an SCF-type ubiquitin ligase complex, induces the degradation of positive regulators of the cell cycle. We demonstrate that inactivation of Fbxw7 in hematopoietic cells causes premature depletion of HSCs due to active cell cycling and p53-dependent apoptosis. Interestingly, Fbxw7 deletion also confers a selective advantage to cells with suppressed p53 function, eventually leading to development of T-cell acute lymphoblastic leukemia (T-ALL). Thus, Fbxw7 functions as a fail-safe mechanism against both premature HSC loss and leukemogenesis.

The C syndrome is characterized by trigonocephaly and associated anomalies, such as unusual facies, psychomotor retardation, redundant skin, joint and limb abnormalities, and visceral anomalies. In an individual with the C syndrome who harbors a balanced chromosomal translocation, t(3;18)(q13.13;q12.1), we discovered that the TACTILE gene for CD96, a member of the immunoglobulin superfamily, was disrupted at the 3q13.3 breakpoint. In mutation analysis of nine karyotypically normal patients given diagnoses of the C or C-like syndrome, we identified a missense mutation (839C--T, T280M) in exon 6 of the CD96 gene in one patient with the C-like syndrome. The missense mutation was not found among 420 unaffected Japanese individuals. Cells with mutated CD96 protein (T280M) lost adhesion and growth activities in vitro. These findings indicate that CD96 mutations may cause a form of the C syndrome by interfering with cell adhesion and growth.