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Three types of adipocytes, white, brown, and beige, regulate the systemic energy balance through the storage and expenditure of chemical energy. In addition, adipocytes produce various bioactive molecules known as adipokines. In contrast to white adipocyte‐derived molecules, less information is available on the adipokines produced by brown adipocytes (batokine). This study explored the regulatory expression of interleukin (IL)‐6 in cell culture studies. Norepinephrine or a nonselective β‐adrenergic receptor agonist increased the expression of IL‐6 in primary brown adipocytes and HB2 brown adipocytes. Treatment with forskolin (Fsk), an activator of the cAMP‐dependent protein kinase (PKA) pathway (downstream signaling of the β‐adrenergic receptor), efficiently stimulated IL‐6 expression in brown adipocytes and myotubes. Phosphorylated CREB and phosphorylated p38 MAP kinase levels were increased in Fsk‐treated brown adipocytes within 5 min. In contrast, a long‐term (∼60 min and ∼4 h) treatment with Fsk was required for increase in STAT3 phosphorylation and C/EBPβ expression, respectively. The PKA, p38 MAP kinase, STAT3, and C/EBPβ pathways are required for the maximal IL‐6 expression induced by Fsk, which were verified by use of various inhibitors of these signal pathways. Vitamin C enhanced Fsk‐induced IL‐6 expression through the extracellular signal‐regulated kinase activity. The present study provides basic information on the regulatory expression of IL‐6 in activated brown adipocytes. Significance statement: White adipocytes accumulate excess energy as fat, whereas brown adipocytes consume the chemical energy of fat and carbohydrates as heat. Adipocytes also secrete bioactive molecules called adipokine. Interleukin‐6 (IL‐6) is produced not only in white adipocytes but also brown adipocytes, but the regulation of IL‐6 expression in brown adipocytes is unclear. We explored the mechanisms underlying IL‐6 gene induction in activated brown adipocytes. Forskolin increased IL‐6 expression in brown adipocytes through stimulated phosphorylation of CREB, p38 MAP kinase, and STAT3. In addition, C/EBPβ induction was required for the enhancement of IL‐6 induction. Vitamin C also promoted forskolin‐induced IL‐6 expression. The present study provides basic information on the regulatory expression of IL‐6 in activated brown adipocytes. [ABSTRACT FROM AUTHOR]

Hepcidin negatively regulates the circulating iron levels by inhibiting the intestinal absorption of iron as well as iron release from macrophages. Hepcidin activity is largely determined by its expression, which is regulated at the transcriptional level. Hepcidin transcription is induced not only by the iron status‐related bone morphogenetic protein (BMP)‐2/6, but also by inflammatory cytokines, such as interleukin (IL)‐1β and IL‐6. The present study reveals that the microphthalmia (MiT)/transcription factor E (TFE) family members are novel regulators of hepcidin transcription. Melanocyte‐inducing transcription factor (MITF)‐A, a member of the MiT/TFE family, was identified as a positive regulator of hepcidin transcription via stimulus screening for transcription regulators. An E‐box (5′‐CATGTG‐3′) spanning nt‐645 to nt‐640 of the murine hepcidin promoter was identified as an MITF‐A‐responsive element. Responsiveness to MITF‐A on hepcidin transcription decreased when the cells were stimulated with BMP2 or IL‐1β. These results suggest a functional interaction between the MITF pathway and BMP‐ or IL‐1β‐mediated signaling. TFEB and TFE3, members of the MiT/TFE family, also stimulated hepcidin transcription, but the main region responsible for hepcidin transcription was distinct from that induced by MITF‐A. The region spanning nt‐581 to nt‐526 was involved in TFEB/TFE3‐mediated hepcidin transcription. Considering that members of the MiT/TFE family act as regulators of starvation‐induced lysosomal biogenesis, hepcidin expression may be controlled by additional pathways apart from those identified so far. Significance statement: Systemic iron levels are negatively regulated by hepatic transcription of hepcidin. Hepcidin transcription has been shown to be mainly regulated by iron levels and inflammation, but recent evidence suggested the involvement of the other factors in hepcidin transcription. The present study identified novel inducers of hepcidin transcription; melanocyte‐inducing transcription factor (MITF)‐A, TFEB, and TFE3, members of the MiT/TFE family, stimulated hepcidin transcription. MITF‐A modified the bone morphogenetic protein‐ or interleukin‐1β‐mediated hepcidin transcription. Furthermore, region responsible for MITF‐mediated hepcidin transcription was distinct from that induced by TFEB/TFE3. Considering that members of the microphthalmia/transcription factor E (TFE) family act as regulators of starvation‐induced lysosomal biogenesis, hepcidin expression may be controlled by additional pathways apart from those identified so far. [ABSTRACT FROM AUTHOR]

Activin B, a homodimer of the inhibin βB subunit, acts as a regulator of gonadal function and as an adipokine. To clarify the role of activin B in dogs, we characterized the canine inhibin βB gene and signalling pathways regulated by the canine inhibin βB. Using 5′‐ and 3′‐rapid amplification of cDNA end (RACE) and RT‐PCR on RNA isolated from the ovary of dogs, we identified short and long forms of the inhibin βB gene. Immunoreactive inhibin βB molecules were detected at ~25 and ~14 kDa under nonreducing and reducing conditions, respectively, in culture supernatants from HEK293 cells transfected with a plasmid containing the long form of the inhibin βB gene, indicating activin B production and secretion. Similar to human and murine activin B, the canine activin B‐stimulated transcriptions of reporter genes, CAGA‐luc and Hepcidin‐luc, regulated by the canonical activin/transforming growth factor‐β (TGF‐β) and bone morphogenetic protein (BMP) pathway, respectively. Activin B‐induced CAGA‐luc transcription was not detected in ALK7‐deficient MDCK canine‐derived cells; however, the forced expression of ALK7 resulted in the activin B‐dependent expression in MDCK cells. Unexpectedly, the activin B‐induced activation of the BMP pathway was partially blocked by the inhibition of endogenous activin/TGF‐β receptor activity. The present study identified an experimentally isolated long form of the canine inhibin βB gene producing activin B that transactivates BMP‐ and activin/TGF‐β‐regulated gene expression. [ABSTRACT FROM AUTHOR]

BACKGROUND Magnesium (Mg) is highly bioavailable in kombu compared with other edible seaweeds. However, a considerable amount of Mg is lost during industrial processing and cooking of kombu. We hypothesized that thinly shaved kombu (TSK), a traditional Japanese kombu product, is a suitable Mg source for daily diets because TSK hardly loses Mg during processing. Rats were fed diets containing TSK or magnesium oxide (MgO) to satisfy 25%, 50%, 75%, or 100% of their Mg requirements. We determined the relative Mg bioavailability of TSK compared to MgO and examined factors affecting Mg bioavailability in TSK. RESULTS: The relative bioavailability of Mg in TSK compared with MgO was calculated as 92.3%, 111.4%, and 87.2% from apparent absorption, urinary excretion, and femoral concentration of Mg, respectively. The ultrafiltrable Mg concentration was lower in the cecal content of rats given TSK than those given MgO. However, the mRNA expression of TRPM6, an Mg channel responsible for Mg absorption, was higher in the cecum of rats given TSK than those given MgO. CONCLUSION: Enhancement of TRPM6 expression in the large intestine negates the low bioaccessibility of Mg in TSK, and thus TSK shows Mg bioavailability comparable with MgO. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Uncoupling protein 1 (UCP1) is responsible for non‐shivering thermogenesis, with restricted expression in brown/beige adipocytes in humans and rodents. We have previously shown an unexpected expression of UCP1 in bovine skeletal muscles. This study evaluated factors affecting Ucp1 gene expression in cultured bovine myogenic cells. Myosatellite cells, which were isolated from the bovine musculus longissimus cervicis, were induced to differentiate into myotubes in the presence of 2% horse serum. Previous studies using murine brown/beige adipocytes revealed that Ucp1 expression levels are directly increased by forskolin and all‐trans retinoic acid (RA). The transforming growth factor‐β (TGF‐β)/activin pathway negatively regulated Ucp1 expression, whereas activation of the bone morphogenetic protein (BMP) pathway indirectly increases Ucp1 expression through the stimulation of brown/beige adipogenesis. Neither forskolin nor RA significantly affected Ucp1 mRNA levels in bovine myogenic cells. A‐83‐01, an inhibitor of the TGF‐β/activin pathway, stimulated myogenesis in these cells. A‐83‐01 significantly increased the expression of some brown fat signature genes such as Pgc‐1α, Cox7a1, and Dio2, with a quantitative but not significant increase in the expression of Ucp1. Treatment with LDN‐193189, an inhibitor of the BMP pathway, did not affect the differentiation of bovine myosatellite cells. Rather, LDN‐193189 increased Ucp1 mRNA levels without modulating the levels of other brown/beige adipocyte‐related genes. The current results indicate that the regulation of Ucp1 expression in bovine myogenic cells is distinct from that in murine brown/beige adipocytes, which has been more intensely characterized. Significance of the study: We previously reported unexpected expression of Ucp1 in bovine muscle tissues; Ucp1 expression has been known to be detected predominantly in brown/beige adipocytes. This study examined regulatory expression of bovine Ucp1 in myogenic cells. Consistent with the changes in expression levels of brown/beige adipocyte‐selective genes, Ucp1 expression tended to be increased by inhibition of endogenous TGF‐β activity. In contrast, inhibition of endogenous BMP significantly increased Ucp1 expression without affecting brown/beige adipocyte‐selective gene expression. The current results indicate that regulatory expression of Ucp1 in bovine myogenic cells is distinct from that in murine brown/beige adipocytes that is more intensely characterized. [ABSTRACT FROM AUTHOR]

Dietary vitamin A status affects energy metabolism. The present study explored the effect of all‐trans retinoic acid (ATRA) on the expression levels of molecules and metabolites of brown adipocytes. Chronic ATRA treatment was initiated during the early stage (days 0‐8) or late stage (days 8‐12) of adipogenesis. Treatment with ATRA during the early and late stage of adipogenesis resulted in an increase in the expression level of Ucp1 and Cidea, genes highly expressed in brown adipocytes, on day 8 and day 12, respectively, whereas expression of Pgc‐1α, another gene expressed during brown adipogenesis, was unaffected by ATRA. Non‐targeted metabolomic analyses indicated that the pathways related to the glucose metabolism were affected by ATRA, irrespective of the differentiation stage. Cellular levels of glucose 6‐phosphate, fructose 6‐phosphate, citric acid, and succinic acid decreased after ATRA treatment on days 8 and 12. In contrast, glucose level was higher in ATRA‐treated cells on day 8, but it was lower on day 12. ATRA decreased the cellular level of aconitic acid, fumaric acid, and malic acid on day 12 but not on day 8. Furthermore, ATRA increased the expression level of Hxk2 and downregulated the expressions of G6pdh and Pfkl/Pfkp on day 8 but not on day 12. Together, the results indicate that the chronic treatment with ATRA stimulated the formation of activated brown adipocytes, eventually leading to alterations in the levels of cellular metabolites related to glucose metabolism. Significance of the study: Significance of the study treatment with all‐trans retinoic acid (ATRA) during the early and late stage of adipogenesis increased the expression of Ucp1 and Cidea, genes highly expressed in brown adipocytes, on day 8 and day 12. Cellular levels of glucose 6‐phosphate, fructose 6‐phosphate, citric acid, and succinic acid decreased after ATRA treatment on days 8 and 12. In contrast, glucose level was higher in ATRA‐treated cells on day 8, but it was lower on day 12. The present results indicate that ATRA stimulated the formation of activated brown adipocytes, eventually leading to alterations in the levels of cellular metabolites related to glucose metabolism. [ABSTRACT FROM AUTHOR]

Activity of brown/beige adipocytes is higher in women than in men. The expression level of uncoupling protein 1 (UCP1) is largely consistent with the thermogenic activity in brown/beige adipocytes. The present study examined the direct effects of sex hormones on Ucp1 expression in brown adipocytes and beige adipocytes, which were differentiated from HB2 brown preadipocytes and 3T3‐L1 white preadipocytes, respectively; treatment with estradiol or testosterone was used during the early (days 0‐8) or late stage (days 8‐12) of brown adipogenesis and beige adipogenesis. On day 8 or day 12, cells were treated with or without isoproterenol (Iso), an agonist for the β‐adrenergic receptor, for 4 hours. Furthermore, the sex of cells was examined; the sex‐determining region y gene, which is located on the y chromosome, was present in HB2 cells, but not in 3T3‐L1 cells, suggesting that HB2 cells and 3T3‐L1 cells are male and female cells, respectively. Treatment with 17β‐estradiol during the early stage of brown adipogenesis enhanced the responsiveness to Iso on Ucp1 induction, whereas treatment during the late stage of brown adipogenesis decreased Ucp1 expression in unstimulated brown adipocytes. Estradiol decreased Iso‐induced Ucp1 expression during the early stage of beige adipogenesis. Treatment with testosterone during the early stage of brown adipogenesis did not affect Ucp1 expression but increased the responsiveness to Iso on Ucp1 induction by the treatment during the late stage of brown adipogenesis. The present results suggest that sex hormones modulate the expression level of Ucp1 in brown/beige adipocytes in a stage‐dependent manner. Direct effects of sex hormones in brown/beige adipogenesis were evaluated. Treatment with 17β‐estradiol during the early stage of brown adipogenesis enhanced the responsiveness to isoproterenol (Iso), an agonist for the β‐adrenergic receptor, on Ucp1 induction, whereas treatment during the late stage of brown adipogenesis decreased Ucp1 expression in unstimulated brown adipocytes. Estradiol decreased Iso‐induced Ucp1 expression during the early stage of beige adipogenesis. Testosterone during the late stage of brown adipogenesis increased the responsiveness to Iso on Ucp1 induction. Sex hormones modulate the expression level of Ucp1 in brown/beige adipocytes in a stage‐dependent manner. [ABSTRACT FROM AUTHOR]

Abstract: Long‐distance transportation has negative impacts on production and health in cattle. Feed and water are routinely deprived from cattle during transportation. We investigated whether niacin supplementation could improve niacin nutrition and mitigate the adverse effect of transportation with feed and water deprivation in steer calves. We also studied the adverse effect of feed and water deprivation in nontransported steer calves. Twelve calves were assigned to feed and water deprivation for 2 days, or full access to feed and water in experiment 1. Ten calves were assigned to 2‐day transportation with feed and water deprivation, or the transportation with feed and water deprivation, but with supplementation of rumen‐protected niacin at 100 g/day per head in experiment 2. Bodyweight was measured and blood was collected for 32 days in each experiment. Feed and water deprivation temporarily decreased serum glucose concentrations and bodyweight gain. Transportation with deprivation of feed and water caused a temporal decrease in bodyweight gain and serum albumin concentration, and a continuous decrease in serum glucose and total cholesterol concentrations, which was suppressed by niacin supplementation. Niacin supplementation increased blood niacin concentration. These results suggest that niacin supplementation mitigates adverse effects of transportation with feed and water deprivation in steer calves. [ABSTRACT FROM AUTHOR]

Brown/beige adipocytes dissipate energy as heat. We previously showed that brown/beige adipocytes are present in white adipose tissue (WAT) of fattening cattle. The present study examined the effect of vitamin A restriction on mRNA expression of brown/beige adipocyte-related genes. In Japan, fattening cattle are conventionally fed a vitamin A-restricted diet to improve beef marbling. Twelve Japanese Black steers aged 10 mo were fed control feed (n = 6) or vitamin A-restricted feed (n = 6) for 20 mo. Subcutaneous WAT (scWAT) and mesenteric WAT (mesWAT) were collected, and mRNA expression levels of molecules related to the function of brown/beige adipocytes (Ucp1, Cidea, Dio2, Cox7a, and Cox8b) as well as transcriptional regulators related to brown/beige adipogenesis (Zfp516, Nfia, Prdm16, and Pgc-1a) were evaluated. The vitamin A restriction significantly increased or tended to increase expression levels of Cidea and Pgc-1a in scWAT, and Cidea, Dio2, and Nfia in mesWAT. Previous studies revealed that the bone morphogenetic protein (Bmp) pathway was responsible for commitment of mesenchymal stem cells to brown/beige adipocyte-lineage cells. The vitamin A restriction increased expression of Bmp7 and some Bmp receptors in WAT. The interrelationship between gene expression levels indicated that expression levels of Nfia, Prdm16, and Pgc-1a were closely related to those of genes related to the function of brown/beige adipocytes in scWAT. Also, expression levels of Nfia, Prdm16, and Pgc- 1a were highly correlated with those of Alk3 in scWAT. In summary, the present results suggest that the vitamin A restriction increases the number or activity of brown/beige adipocytes through regulatory expression of transcriptional regulators to induce brown/beige adipogenesis, especially in scWAT of fattening cattle, which may be governed by the Bmp pathway. [ABSTRACT FROM AUTHOR]

Abstract: The relationship between mineral concentrations, and the relationship of mineral concentrations with physicochemical characteristics in muscles were investigated using the Longissimus thoracis (LT) muscle of 44 Japanese Black steers. We determined moisture content, fat content, meat color, fatty acid composition and mineral concentrations in the LT muscle. Magnesium (Mg), potassium (K) and zinc (Zn) concentrations had negative correlations with fat content, but sodium (Na), manganese (Mn), copper (Cu) and molybdenum (Mo) concentrations were not correlated with fat content. The concentrations of Mg, Mn, Fe, Cu and Zn largely and positively contributed to the first principal component of mineral concentrations. Because the red muscle was rich in these minerals compared to the white muscle, the variation of these minerals probably results from the abundance of red fibers in the LT muscle. The concentration of K was positively correlated with moisture content but Na concentration was not related to moisture content, suggesting that the intracellular fluid volume can largely affect moisture content. The results of the present experiment suggest that mineral concentrations reflect some traits such as not only fat content but also the composition of myofiber type and the intracellular fluid volume in the LT muscle of Japanese Black cattle. [ABSTRACT FROM AUTHOR]

Long-distance transportation is sometimes inevitable in the beef industry because of the geographic separation of major breeding and fattening areas. Long-distance transportation negatively impacts production and health of cattle, which may, at least partly, result from the disturbance of metabolism during and after transportation. However, alteration of metabolism remains elusive in transported cattle. We investigated the effects of transportation on the metabolomic profiles of Holstein steer calves. Non-targeted analysis of serum concentrations of low molecular weight metabolites was performed by gas chromatography mass spectrometry. Transportation affected 38 metabolites in the serum. A pathway analysis suggested that 26, 10, and 10 pathways were affected immediately after transportation, and 3 and 7 days after transportation, respectively. Some pathways were disturbed only immediately after transportation, likely because of feed and water withdrawal during transit. Nicotinate and nicotinamide metabolism, and citric acid cycle were affected for 3 days after transportation, whereas propionate metabolism, phenylalanine and tyrosine metabolism were affected throughout the experiment. Four pathways were not affected immediately after transportation, but were altered thereafter. These results suggested that many metabolic pathways had marked perturbations during transportation. Metabolites such as citric acid, propionate, tyrosine and niacin can be candidate supplements for mitigating transportation-induced adverse effects. [ABSTRACT FROM AUTHOR]

Four Japanese Black steers (16 months of age) were assigned to a 4 × 4 Latin square design to investigate the effect of graded levels of sweet-potato condensed distillers solubles (SCDS) in their diets on intake and urinary excretion of minerals. The four diets consisted of 0%, 10%, 20% and 30% (dry matter (DM) basis) SCDS, with SCDS replacing commercial concentrate (CC). Intake of K, Cl, S, P and Mg increased linearly with increasing SCDS content. Urinary pH increased linearly with increasing dietary SCDS content. SCDS feeding increased urinary K concentrations (linear and quadratic effects). Urinary concentrations of Cl increased linearly with increasing SCDS content. In contrast, urinary concentrations of Mg decreased with increasing SCDS content. Feeding of SCDS did not apparently affect urinary NH3,P, Na or Ca concentrations. These results suggest that high SCDS feeding is not a risk for crystallization of minerals leading to the formation of magnesium-phosphate type calculi: although SCDS contains large amounts of P and Mg, high SCDS feeding decreased the Mg concentration and did not affect the P concentration in urine. Additionally, high SCDS feeding had no apparent effects on plasma concentrations of Na, K, Cl, Ca or inorganic P. [ABSTRACT FROM AUTHOR]