Activation of classical brown adipocytes in the adult human perirenal depot is highly correlated with PRDM16-EHMT1 complex expression

Brown fat generates heat to protect against cold and obesity. Adrenergic stimulation activates the thermogenic program of brown adipocytes. Although the bioactivity of brown adipose tissue in adult humans had been assumed to very low, several studies using positron emission tomography-computed tomography (PET-CT) have detected bioactive brown adipose tissue in adult humans under cold exposure. In this study, we collected adipose tissues obtained from the perirenal regions of adult patients with pheochromocytoma (PHEO) or non-functioning adrenal tumors (NF). We demonstrated that perirenal brown adipocytes were activated in adult patients with PHEO. These cells had the molecular characteristics of classical brown fat rather than those of beige/brite fat. Expression of brown adipose tissue markers such as uncoupling protein 1 (UCP1) and cell death-inducing DFFA-like effector A (CIDEA) was highly correlated with the amounts of PRD1-BF-1-RIZ1 homologous domain-containing protein-16 (PRDM16) - euchromatic histone-lysine N-methyltransferase 1 (EHMT1) complex, the key transcriptional switch for brown fat development. These results provide novel insights into the reconstruction of human brown adipocytes and their therapeutic application against obesity and its complications such as type 2 diabetes.

Macrophage deficiency in osteopetrotic (op/op) mice inhibits activation of satellite cells and prevents hypertrophy in single soleus fibers

Effects of macrophage on the responses of soleus fiber size to hind limb unloading and reloading were studied in osteopetrotic homozygous (op/op) mice with inactivated mutation of macrophage colony-stimulating factor (M-CSF) gene and in wild-type (+/+) and heterozygous (+/op) mice. The basal levels of mitotically active and quiescent satellite cell (-46 and -39% vs. +/+, and -40 and -30% vs. +/op) and myonuclear number (-29% vs. +/+ and -28% vs. +/op) in fibers of op/op mice were significantly less than controls. Fiber length and sarcomere number in op/op were also less than +/+ (-22%) and +/op (-21%) mice. Similar trend was noted in fiber cross-sectional area (CSA, -15% vs. +/+, P = 0.06, and -14% vs. +/op, P = 0.07). The sizes of myonuclear domain, cytoplasmic volume per myonucleus, were identical in all types of mice. The CSA, length, and the whole number of sarcomeres, myonuclei, and mitotically active and quiescent satellite cells, as well as myonuclear domain, in single muscle fibers were decreased after 10 days of unloading in all types of mice, although all of these parameters in +/+ and +/op mice were increased toward the control values after 10 days of reloading. However, none of these levels in op/op mice were recovered. Data suggest that M-CSF and/or macrophages are important to activate satellite cells, which cause increase of myonuclear number during fiber hypertrophy. However, it is unclear why their responses to general growth and reloading after unloading are different.

Mosapride citrate improves nonalcoholic steatohepatitis with increased fecal lactic acid bacteria and plasma glucagon-like peptide-1 level in a rodent model

Several lines of evidence have suggested a role of gut microbiota in the etiology of nonalcoholic steatohepatitis (NASH). NASH subjects reportedly showed a prolonged orocecal transit time coexistent with small intestinal bacterial overgrowth. We considered the possibility that enhanced gastrointestinal motility would influence gut microbiota and thus investigated the effects of the gastroprokinetic agent mosapride citrate (MC) on gut microbiota and the development of NASH using a methionine-choline deficient (MCD) diet-fed rodent model. Mice were divided into three groups, given the normal chow diet (NCD), the MCD diet, or the MCD diet containing 10 mg·kg(-1)·day(-1) of MC (MCD plus MC) for 6 wk. NASH development was evaluated based on hepatic histochemical findings, serum parameters and various mRNA and/or protein expression levels. MC treatment suppressed MCD diet-induced NASH development, with reduced serum lipopolysaccharide and increased plasma glucagon-like peptide-1 (GLP-1) concentrations. Calculation of the relative abundance of each strain based on gut microbiota analyses indicated lactic acid bacteria specifically, such as Bifidobacterium and Lactobacillus, in feces to be decreased in the MCD, compared with the NCD group. Interestingly, the reduction in lactic acid bacteria in the MCD diet group was reversed in the MCD plus MC group. In addition, colon inflammation observed in the MCD diet group was reduced in the MCD plus MC group. Therefore, MC showed a protective effect against MCD diet-induced NASH development in our rodent model, with possible involvements of increased fecal lactic acid bacteria, protection against colon inflammation and elevated plasma GLP-1.

A Patient with an Extra-adrenal Pheochromocytoma and Germ-line SDHB Mutation Accompanied by an Atypical Meningioma

The gene succinate dehydrogenase subunit B (SDHB) encodes a protein comprising part of the mitochondrial complex II, which links the Krebs cycle and the electron-transport chain. Heterozygous germ-line SDHB mutations causes familial pheochromocytoma-paraganglioma syndrome and has also been linked to gastrointestinal stromal tumors, as well as renal cell carcinomas. We herein report a patient with a germ-line SDHB mutation who presented with an atypical meningioma that was identified as originating from a somatic SDHB mutation. The 41-year-old man, who had a surgical history of extra-adrenal pheochromocytoma at 23 years of age, recently developed gait disorder and hypertension. At the radiological examination, a tumor was detected in the cervical spinal cord at the C6-7 intervertebral level. The pathological findings of the isolated tumor were atypical meningioma assessed as grade II according to the World Health Organization criteria. Inherited neoplasia syndrome was suspected because of the patient's history of early-onset extra-adrenal pheochromocytoma and the development of meningioma. We therefore performed molecular genetic analyses. A direct sequence analysis revealed a heterozygous germ-line frameshift mutation in SDHB, specifically an 11-nucleotide deletion, c.305-315delCAATGAACATC, in exon 4, resulting in a frameshift p.A102EfsX12. Additionally, the sequence analysis of the tumor DNA revealed only a mutated allele with a frameshift mutation in the germ-line SDHB. Our findings suggest that SDHB plays an important role in the pathogenesis of meningiomas as well as pheochromocytomas. Therefore, a differential diagnosis for metastatic pheochromocytoma and other new onset tumors, including meningioma, particularly in patients with germ-line SDHB mutations and a previous history of pheochromocytoma should be carefully made.

Additional strange hadrons from QCD thermodynamics and strangeness freezeout in heavy ion collisions

We compare lattice QCD results for appropriate combinations of net strangeness fluctuations and their correlations with net baryon number fluctuations with predictions from two hadron resonance gas (HRG) models having different strange hadron content. The conventionally used HRG model based on experimentally established strange hadrons fails to describe the lattice QCD results in the hadronic phase close to the QCD crossover. Supplementing the conventional HRG with additional, experimentally uncharted strange hadrons predicted by quark model calculations and observed in lattice QCD spectrum calculations leads to good descriptions of strange hadron thermodynamics below the QCD crossover. We show that the thermodynamic presence of these additional states gets imprinted in the yields of the ground-state strange hadrons leading to a systematic 5-8 MeV decrease of the chemical freeze-out temperatures of ground-state strange baryons.

Design and fabrication of a perpendicular magnetic tunnel junction based nonvolatile programmable switch achieving 40% less area using shared-control transistor structure

A compact nonvolatile programmable switch (NVPS) using 90 nm CMOS technology together with perpendicular magnetic tunnel junction (p-MTJ) devices is fabricated for zero-standby-power field-programmable gate array. Because routing information does not change once it is programmed into an NVPS, high-speed read and write accesses are not required and a write-control transistor can be shared among all the NVPSs, which greatly simplifies structure of the NVPS. In fact, the effective area of the proposed NVPS is reduced by 40% compared to that of a conventional MTJ-based NVPS. The instant on/off behavior without external nonvolatile memory access is also demonstrated using the fabricated test chip.

Depinning probability of a magnetic domain wall in nanowires by spin-polarized currents

Current-induced magnetic domain wall motion is attractive for manipulating magnetization direction in spintronics devices, which open a new era of electronics. Up to now, in spite of a crucial significance to applications, investigation on a current-induced domain wall depinning probability, especially in sub-nano to a-few-nanosecond range has been lacking. Here we report on the probability of the depinning in perpendicularly magnetized Co/Ni nanowires in this timescale. A high depinning probability was obtained even for 2-ns pulses with a current density of less than 10¹² A m⁻². A one-dimensional Landau-Lifshitz-Gilbert calculation taking into account thermal fluctuations reproduces well the experimental results. We also calculate the depinning probability as functions of various parameters and found that parameters other than the coercive field do not affect the transition width of the probability. These findings will allow one to design high-speed and reliable magnetic devices based on the domain wall motion.

RISING beamline (BL28XU) for rechargeable battery analysis

The newly installed BL28XU beamline at SPring-8 is dedicated to in situ structural and electronic analysis of rechargeable batteries. It supports the time range (1 ms to 100 s) and spatial range (1 µm to 1 mm) needed for battery analysis. Electrochemical apparatus for battery charging and discharging are available in experimental hutches and in a preparation room. Battery analysis can be carried out efficiently and effectively using X-ray diffraction, X-ray absorption fine-structure analysis and hard X-ray photoelectron spectroscopy. Here, the design and performance of the beamline are described, and preliminary results are presented.

EHMT1 controls brown adipose cell fate and thermogenesis through the PRDM16 complex

Brown adipose tissue (BAT) dissipates chemical energy in the form of heat as a defense against hypothermia and obesity. Current evidence indicates that brown adipocytes arise from Myf5⁺ dermotomal precursors through the action of PRDM16 (PR domain containing protein16) transcriptional complex ^1,2. However, the enzymatic component of the molecular switch that determines lineage specification of brown adipocytes remains unknown. Here we show that EHMT1 (euchromatic histone-lysine N-methyltransferase 1) is an essential BAT-enriched lysine methyltransferase in the PRDM16 transcriptional complex and controls brown adipose cell fate. Loss of EHMT1 in brown adipocytes causes a severe loss of brown fat characteristics and induces muscle differentiation in vivo through demethylation of histone 3 Lys 9 (H3K9me2 and 3) of the muscle-selective gene promoters. Conversely, EHMT1 expression positively regulates the BAT-selective thermogenic program by stabilizing the PRDM16 protein. Notably, adipose-specific deletion of EHMT1 leads to a marked reduction of BAT-mediated adaptive thermogenesis, obesity, and systemic insulin resistance. These data indicate that EHMT1 is an essential enzymatic switch that controls brown adipose cell fate and energy homeostasis.

Strangeness at high temperatures: from hadrons to quarks

Appropriate combinations of up to fourth order cumulants of net strangeness fluctuations and their correlations with net baryon number and electric charge fluctuations, obtained from lattice QCD calculations, have been used to probe the strangeness carrying degrees of freedom at high temperatures. For temperatures up to the chiral crossover, separate contributions of strange mesons and baryons can be well described by an uncorrelated gas of hadrons. Such a description breaks down in the chiral crossover region, suggesting that the deconfinement of strangeness takes place at the chiral crossover. On the other hand, the strangeness carrying degrees of freedom inside the quark gluon plasma can be described by a weakly interacting gas of quarks only for temperatures larger than twice the chiral crossover temperature. In the intermediate temperature window, these observables show considerably richer structures, indicative of the strongly interacting nature of the quark gluon plasma.

Integrator complex plays an essential role in adipose differentiation

The dynamic process of adipose differentiation involves stepwise expressions of transcription factors and proteins specific to the mature fat cell phenotype. In this study, it was revealed that expression levels of IntS6 and IntS11, subunits of the Integrator complex, were increased in 3T3-L1 cells in the period when the cells reached confluence and differentiated into adipocytes, while being reduced to basal levels after the completion of differentiation. Suppression of IntS6 or IntS11 expression using siRNAs in 3T3-L1 preadipocytes markedly inhibited differentiation into mature adipocytes, based on morphological findings as well as mRNA analysis of adipocyte-specific genes such as Glut4, perilipin and Fabp4. Although Pparγ2 protein expression was suppressed in IntS6 or IntS11-siRNA treated cells, adenoviral forced expression of Pparγ2 failed to restore the capacity for differentiation into mature adipocytes. Taken together, these findings demonstrate that increased expression of Integrator complex subunits is an indispensable event in adipose differentiation. Although further study is necessary to elucidate the underlying mechanism, the processing of U1, U2 small nuclear RNAs may be involved in cell differentiation steps.

Human BAT possesses molecular signatures that resemble beige/brite cells

Brown adipose tissue (BAT) dissipates chemical energy and generates heat to protect animals from cold and obesity. Rodents possess two types of UCP-1 positive brown adipocytes arising from distinct developmental lineages: “classical” brown adipocytes develop during the prenatal stage whereas “beige” or “brite” cells that reside in white adipose tissue (WAT) develop during the postnatal stage in response to chronic cold or PPARγ agonists. Beige cells’ inducible characteristics make them a promising therapeutic target for obesity treatment, however, the relevance of this cell type in humans remains unknown. In the present study, we determined the gene signatures that were unique to classical brown adipocytes and to beige cells induced by a specific PPARγ agonist rosiglitazone in mice. Subsequently we applied the transcriptional data to humans and examined the molecular signatures of human BAT isolated from multiple adipose depots. To our surprise, nearly all the human BAT abundantly expressed beige cell-selective genes, but the expression of classical brown fat-selective genes were nearly undetectable. Interestingly, expression of known brown fat-selective genes such as PRDM16 was strongly correlated with that of the newly identified beige cell-selective genes, but not with that of classical brown fat-selective genes. Furthermore, histological analyses showed that a new beige cell marker, CITED1, was selectively expressed in the UCP1-positive beige cells as well as in human BAT. These data indicate that human BAT may be primary composed of beige/brite cells.

Role of Pin1 protein in the pathogenesis of nonalcoholic steatohepatitis in a rodent model

Nonalcoholic steatohepatitis (NASH) is a disorder characterized by simultaneous fat accumulation and chronic inflammation in the liver. In this study, Pin1 expression was revealed to be markedly increased in the livers of mice with methionine choline-deficient (MCD) diet-induced NASH, a rodent model of NASH. In addition, Pin1 KO mice were highly resistant to MCD-induced NASH, based on a series of data showing simultaneous fat accumulation, chronic inflammation, and fibrosis in the liver. In terms of Pin1-induced fat accumulation, it was revealed that the expression levels of peroxisome proliferator-activated receptor α and its target genes were higher in the livers of Pin1 KO mice than in controls. Thus, resistance of Pin1 KO mice to hepatic steatosis is partially attributable to the lack of Pin1-induced down-regulation of peroxisome proliferator-activated receptor α, although multiple other mechanisms are apparently involved. Another mechanism involves the enhancing effect of hematopoietic Pin1 on the expressions of inflammatory cytokines such as tumor necrosis factor and monocyte chemoattractant protein 1 through NF-κB activation, eventually leading to hepatic fibrosis. Finally, to distinguish the roles of hematopoietic or nonhematopoietic Pin1 in NASH development, mice lacking Pin1 in either nonhematopoietic or hematopoietic cells were produced by bone marrow transplantation between wild-type and Pin1 KO mice. The mice having nonhematopoietic Pin1 exhibited fat accumulation without liver fibrosis on the MCD diet. Thus, hepatic Pin1 appears to be directly involved in the fat accumulation in hepatocytes, whereas Pin1 in hematopoietic cells contributes to inflammation and fibrosis. In summary, this is the first study to demonstrate that Pin1 plays critical roles in NASH development. This report also raises the possibility that hepatic Pin1 inhibition to the appropriate level might provide a novel therapeutic strategy for NASH.

Protein sorting by tyrosine-based signals: adapting to the Ys and wherefores

The endocytic and secretory pathways of eukaryotic cells consist of an array of membrane-bound compartments, each of which contains a characteristic cohort of transmembrane proteins. Understanding how these proteins are targeted to and maintained within their appropriate compartments will be crucial for unravelling the mysteries of organelle biogenesis and function. A common event in the sorting of many transmembrane proteins is the interaction between a sorting signal in the cytosolic domain of the targeted protein and a component of an organellar protein coat. Here, we summarize recent findings on the mechanism of sorting by one type of signal, characterized by the presence of a critical tyrosine (Y) residue, and attempt to integrate these findings into a hypothetical model for protein sorting in the endocytic and late (post-Golgi) secretory pathways.

PPARγ agonists induce a white-to-brown fat conversion through stabilization of PRDM16 protein

Brown adipose tissue dissipates energy through heat and functions as a defense against cold and obesity. PPARγ ligands have been shown to induce the browning of white adipocytes; however, the underlying mechanisms remain unclear. Here, we show that PPARγ ligands require full agonism to induce a brown fat gene program preferentially in subcutaneous white adipose. These effects require expression of PRDM16, a factor that controls the development of classical brown fat. Depletion of PRDM16 blunts the effects of the PPARγ agonist rosiglitazone on the induced brown fat gene program. Conversely, PRDM16 and rosiglitazone synergistically activate the brown fat gene program in vivo. This synergy is tightly associated with an increased accumulation of PRDM16 protein, due in large measure to an increase in the half-life of the protein in agonist treated cells. Identifying compounds that stabilize PRDM16 protein may represent a plausible therapeutic pathway for the treatment of obesity and diabetes.

Valsartan, independently of AT1 receptor or PPARγ, suppresses LPS-induced macrophage activation and improves insulin resistance in cocultured adipocytes

Macrophages are integrated into adipose tissues and interact with adipocytes in obese subjects, thereby exacerbating adipose insulin resistance. This study aimed to elucidate the molecular mechanism underlying the insulin-sensitizing effect of the angiotensin II receptor blocker (ARB) valsartan, as demonstrated in clinical studies. Insulin signaling, i.e., insulin receptor substrate-1 and Akt phosphorylations, in 3T3-L1 adipocytes was impaired markedly by treatment with tumor necrosis factor-α (TNFα) or in the culture medium of lipopolysaccharide (LPS)-stimulated RAW 264.7 murine macrophages, and valsartan had no effects on these impairments. However, in contrast, when cocultured with RAW 264.7 cells using a transwell system, the LPS-induced insulin signaling impairment in 3T3-L1 adipocytes showed almost complete normalization with coaddition of valsartan. Furthermore, valsartan strongly suppressed LPS-induced productions of cytokines such as interleukin (IL)-1β, IL-6, and TNFα with nuclear factor-κB activation and c-Jun NH(2)-terminal kinase phosphorylation in RAW 264.7 and primary murine macrophages. Very interestingly, this effect of valsartan was also observed in THP-1 cells treated with angiotensin II type 1 (AT1) siRNA or a peroxisome proliferator-activated receptor-γ (PPARγ) antagonist as well as macrophages from AT1a receptor-knockout mice. We conclude that valsartan suppresses the inflammatory response of macrophages, albeit not via PPARγ or the AT1a receptor. This suppression appears to secondarily improve adipose insulin resistance.