LRP1 in GABAergic neurons is a key link between obesity and memory function

OBJECTIVE

Low-density lipoprotein receptor-related protein-1 (LRP1) regulates energy homeostasis, blood-brain barrier integrity, and metabolic signaling in the brain. Deficiency of LRP1 in inhibitory gamma-aminobutyric acid (GABA)ergic neurons causes severe obesity in mice. However, the impact of LRP1 in inhibitory neurons on memory function and cognition in the context of obesity is poorly understood.

METHODS

Mice lacking LRP1 in GABAergic neurons (Vgat-Cre; LRP1loxP/loxP) underwent behavioral tests for locomotor activity and motor coordination, short/long-term and spatial memory, and fear learning/memory. This study evaluated the relationships between behavior and metabolic risk factors and followed the mice at 16 and 32 weeks of age.

RESULTS

Deletion of LRP1 in GABAergic neurons caused a significant impairment in memory function in 32-week-old mice. In the spatial Y-maze test, Vgat-Cre; LRP1loxP/loxP mice exhibited decreased travel distance and duration in the novel arm compared with controls (LRP1loxP/loxP mice). In addition, GABAergic neuron-specific LRP1-deficient mice showed a diminished capacity for performing learning and memory tasks during the water T-maze test. Moreover, reduced freezing time was observed in these mice during the contextual and cued fear conditioning tests. These effects were accompanied by increased neuronal necrosis and satellitosis in the hippocampus. Importantly, the distance and duration in the novel arm, as well as the performance of the reversal water T-maze test, negatively correlated with metabolic risk parameters, including body weight, serum leptin, insulin, and apolipoprotein J. However, in 16-week-old Vgat-Cre; LRP1loxP/loxP mice, there were no differences in the behavioral tests or correlations between metabolic parameters and cognition.

CONCLUSIONS

Our findings demonstrate that LRP1 from GABAergic neurons is important in regulating normal learning and memory. Metabolically, obesity caused by GABAergic LRP1 deletion negatively regulates memory and cognitive function in an age-dependent manner. Thus, LRP1 in GABAergic neurons may play a crucial role in maintaining normal excitatory/inhibitory balance, impacting memory function, and reinforcing the potential importance of LRP1 in neural system integrity.

LRP1 mediates leptin transport by coupling with the short-form leptin receptor in the choroid plexus

Adipocyte-derived leptin enters the brain to exert its anorexigenic action, yet its transport mechanism is poorly understood. Here we report that LRP1 (low-density lipoprotein receptor-related protein-1) mediates the transport of leptin across the blood-CSF barrier in Foxj1 expressing cells highly enriched at the choroid plexus (ChP), coupled with the short-form leptin receptor, and LRP1 deletion from ependymocytes and ChP cells leads to leptin resistance and hyperphagia, causing obesity. Thus, LRP1 in epithelial cells is a principal regulator of leptin transport in the brain.

ROCK1 regulates insulin secretion from β-cells

OBJECTIVE

The endocrine pancreatic β-cells play a pivotal role in maintaining whole-body glucose homeostasis and its dysregulation is a consistent feature in all forms of diabetes. However, knowledge of intracellular regulators that modulate β-cell function remains incomplete. We investigated the physiological role of ROCK1 in the regulation of insulin secretion and glucose homeostasis.

METHODS

Mice lacking ROCK1 in pancreatic β-cells (RIP-Cre; ROCK1^loxP/loxP, β-ROCK1^-/-) were studied. Glucose and insulin tolerance tests as well as glucose-stimulated insulin secretion (GSIS) were measured. An insulin secretion response to a direct glucose or pyruvate or pyruvate kinase (PK) activator stimulation in isolated islets from β-ROCK1^-/- mice or β-cell lines with knockdown of ROCK1 was also evaluated. A proximity ligation assay was performed to determine the physical interactions between PK and ROCK1.

RESULTS

Mice with a deficiency of ROCK1 in pancreatic β-cells exhibited significantly increased blood glucose levels and reduced serum insulin without changes in body weight. Interestingly, β-ROCK1^-/- mice displayed a progressive impairment of glucose tolerance while maintaining insulin sensitivity mostly due to impaired GSIS. Consistently, GSIS markedly decreased in ROCK1-deficient islets and ROCK1 knockdown INS-1 cells. Concurrently, ROCK1 blockade led to a significant decrease in intracellular calcium and ATP levels and oxygen consumption rates in isolated islets and INS-1 cells. Treatment of ROCK1-deficient islets or ROCK1 knockdown β-cells either with pyruvate or a PK activator rescued the impaired GSIS. Mechanistically, we observed that glucose stimulation in β-cells greatly enhanced ROCK1 binding to PK.

CONCLUSIONS

Our findings demonstrate that β-cell ROCK1 is essential for glucose-stimulated insulin secretion and for glucose homeostasis and that ROCK1 acts as an upstream regulator of glycolytic pyruvate kinase signaling.

[Clinical features and spinal lesions in patients with chronic prostatitis/chronic pelvic pain syndrome]

Objective: To analyze the clinical features and spinal lesions related to micturitionin of chronic prostatitis/chronic pelvic pain syndrome(CP/CPPS) patients. Methods: Patients with CP/CPPS were enrolled to this study at the outpatient department of Tongji Hospital between January and June 2019. The data of clinical features was collected and analyzed, including lower urinary tract symptoms(LUTS), bowel syndrome and pain over different parts of body, as well as lower urinary tract dysfunction, spinal lesions and pelvic organ morphological changes demonstrated by MRI. The potential role of spinal lesions in the development of CP/CPPS syndrome was investigated. Results: A total of 126 CP/CPPS patients were included, with an age［M（Q₁，Q₃）］of 41(31,53) years and a course of disease of 2(1,20) years. Among them, 126 (100.0%) were complicated with LUTS, 72(57.1%) with bowel dysfunction and 88(69.8%) with pain. MRI showed the cervical central disc herniation(126 cases, 100.0%), the ischemic changing in the cervical area of visceral efferant pathway(82 cases, 65.1%), the lumbar central disc herniation(65 cases, 51.6%), and the sacral nerve cysts(97 cases, 77.0%) are commonly seen. In addition, the morphological changes in the visceral organs containing smooth muscle were demonstrated, including thickened bladder wall(91 cases, 72.2%), distended seminal vesicles(70 cases, 55.6%) and distended sigmoid colon/rectum(59 cases, 46.8%). Conclusions: CP/CPPS patients were characterized by the co-existence of LUTS, bowel dysfunction and somatic pain in one individual. The presence of multi-organ symptoms, combined with the high prevalence of spinal lesions associated with micturition reflex, suggesting the potential role of the spinal lesions in the development of CP/CPPS.

LRP1 regulates food intake and energy balance in GABAergic neurons independently of leptin action

Low-density lipoprotein receptor-related protein 1 (LRP1) is a member of LDL receptor family that plays a key role in systemic glucose and lipid homeostasis. LRP1 also regulates energy balance in the hypothalamus by mediating leptin's anorexigenic action, although the underlying neurocircuitry involved is still unclear. Because GABAergic neurons are a major mediator of hypothalamic leptin action, we studied the role of GABAergic LRP1 in energy balance and leptin action using mice lacking LRP1 in Vgat- or AgRP-expressing neurons (Vgat-Cre; LRP1^loxP/loxP or AgRP-Cre; LRP1^loxP/loxP). Here, we show that LRP1 deficiency in GABAergic neurons results in severe obesity in male and female mice fed a normal-chow diet. This effect is most likely due to increased food intake and decreased energy expenditure and locomotor activity. Increased adiposity in GABAergic neuron-specific LRP1-deficient mice is accompanied by hyperleptinemia and hyperinsulinemia. Insulin resistance and glucose intolerance in these mice are occurred without change in body weight. Importantly, LRP1 in GABAergic neurons is not required for leptin action, as evidenced by normal leptin's anorexigenic action and leptin-induced hypothalamic Stat3 phosphorylation. In contrast, LRP1 deficiency in AgRP neurons has no effect on adiposity and caloric intake. In conclusion, our data identify GABAergic neurons as a key neurocircuitry that underpins LRP1-dependent regulation of systemic energy balance and body-weight homeostasis. We further find that the GABAergic LRP1 signaling pathway modulates food intake and energy expenditure independently of leptin signaling and AgRP neurons.

[Characteristics of newly reported HIV/AIDS cases with non-marital or non-commercial heterosexual transmission in Guangxi Zhuang Autonomous Region, 2015-2018]

Objective: To understand the characteristics and associated factors of newly reported HIV/AIDS cases with non-marital or non-commercial heterosexual transmission, in Guangxi Zhuang Autonomous Region (Guangxi), 2015-2018. Methods: Information of newly reported HIV/AIDS cases aged ≥18 years in Guangxi between 2015 and 2018 was collected from the National Comprehensive HIV/AIDS Information System. Unconditional logistic regression model was used to access those factors that were associated with HIV infections through non-marital or non-commercial heterosexual contact. Results: Between 2015 and 2018, a total number of 35 497 HIV/AIDS cases, aged ≥18 years were newly reported in Guangxi. Among them, 32 648 (92.0%) were infected heterosexually while 10 500 were infected through non-marital or non-commercial heterosexual behavior. Non-marital or non-commercial heterosexual transmission accounted for 29.6% (10 500/35 497) of the newly reported HIV/AIDS cases, and 32.2% (10 500/32 648) of those with heterosexual transmission. Males counted for 53.5% (5 617/10 500) of non-marital or non-commercial heterosexual transmission and males to females ratio was 1.2∶1 (5 617∶4 883). Those married or had regular sexual partners counted for 55.9% (5 873/10 500). Commercial heterosexual transmission appeared the main mode of HIV transmission for males (64.4%,16 516/25 633) while main mode for females was non-marital or non-commercial heterosexual transmission and counted for 49.5% (4 883/9 864). Results from the multivariate logistic regression analysis showed that adjusted OR of female HIV/AIDS infected HIV via non-marital or non-commercial heterosexual transmission, was 3.98 times (95%CI: 3.78-4.20) hight than that of males. Among the group aged<50 years and the aged 50-59 years, the adjusted ORs were 1.35 times (95%CI: 1.27-1.44) and 1.13 times (95%CI: 1.05-1.21) hight than that of aged ≥60 years. Those who were single/divorced/widowed, the adjusted OR was 1.53 times (95%CI: 1.45-1.61) hight than that of those married/regular partners. Those with junior high school education, high school education and above the adjusted ORs were 1.22 times (95%CI: 1.16-1.29) and 1.18 times (95%CI: 1.10-1.27), compared to those only with education levels of primary school or below. Conclusions: The number of HIV/AIDS cases via non-marital or non-commercial heterosexual transmission accounted for nearly 30.0% of all the routes of HIV transmission in Guangxi, 2015-2018. Female, aged<60 years old, single/divorced/widowed and having had junior and above high school education etc., appeared as risk factors on non-marital or non-commercial heterosexual transmission, among newly reported HIV/AIDS in Guangxi.

[Influence on physical development of children aged 18 months from HIV-positive mothers for prevention mother to child transmission of HIV]

Objective: To explore influence on physical development of children aged 18 months from HIV-positive mothers for prevention mother to child transmission of HIV (PMTCT) in Guangxi Zhuang autonomous region, and provide evidence for the improvement PMTCT program. Methods: This retrospective case control study was conducted in 554 HIV negative infants aged 18 months whose HIV positive mothers had received PMTCT services reported through PMTCT system database from January 1, 2010 to December 31, 2017 and 1 109 healthy infants born in 2017, whose mothers were healthy, in Lingshan, Luzhai, and Hengxian counties, ranking top three counties with high HIV infection prevalence, in Guangxi. PMTCT data and physical development data such as height, weight and head circumference of children aged 18 months were collected. The physical dysplasia in the infants was defined as at least one of the three main indicators of height, weight and head circumference below the normal range. Results: The number of HIV-positive mother and their infants in the case group were 667 and 554 respectively, and the PMTCT rates were 91.15% (608/667) and 96.57% (535/554) respectively. HIV positive rate, mortality rate and mother to child transmission rate of the infants aged 18 months were 1.44% (8/554), 3.07% (17/554) and 1.91% (8/418) respectively, and the physical examination results of the infants aged 18 months showed that the physical dysplasia rate was 30.51% (169/554). Among the 1 109 infants in the control group, the physical dysplasia rate was 9.83% (109/1 109). The difference between the case group and the control group was significant (P<0.01). Conclusion: The PMTCT rates of HIV positive mother and their children were more than 90.00%, respectively. However, poor physical development rate of infants aged 18 months were more than 30.00%. The possible influence of PMTCT on physical development of the infants aged 18 months of HIV positive mother's needs to be further studied.

Apolipoprotein J is a hepatokine regulating muscle glucose metabolism and insulin sensitivity

Crosstalk between liver and skeletal muscle is vital for glucose homeostasis. Hepatokines, liver-derived proteins that play an important role in regulating muscle metabolism, are important to this communication. Here we identify apolipoprotein J (ApoJ) as a novel hepatokine targeting muscle glucose metabolism and insulin sensitivity through a low-density lipoprotein receptor-related protein-2 (LRP2)-dependent mechanism, coupled with the insulin receptor (IR) signaling cascade. In muscle, LRP2 is necessary for insulin-dependent IR internalization, an initial trigger for insulin signaling, that is crucial in regulating downstream signaling and glucose uptake. Of physiologic significance, deletion of hepatic ApoJ or muscle LRP2 causes insulin resistance and glucose intolerance. In patients with polycystic ovary syndrome and insulin resistance, pioglitazone-induced improvement of insulin action is associated with an increase in muscle ApoJ and LRP2 expression. Thus, the ApoJ-LRP2 axis is a novel endocrine circuit that is central to the maintenance of normal glucose homeostasis and insulin sensitivity.

Hepatokines are proteins secreted by the liver that can regulate whole body metabolism. Here the authors identify apolipoprotein J as a hepatokine that regulates muscle glucose metabolism and insulin resistance through a low-density lipoprotein receptor-related protein−2 mediated mechanism in mice.

[HIV genetic subtypes and comparison of the first CD(4)(+)T cell counts in newly diagnosed HIV infected patients in Liuzhou, 1998-2012]

Objective: To analyze the change trend of HIV genetic subtypes and compare the first CD(4)(+)T cell counts of newly diagnosed HIV infected patients in Liuzhou from 1998 to 2012, and provide a reference for AIDS prevention and control. Methods: Newly diagnosed HIV-infected patients from 1998 to 2012 in Liuzhou were selected through national HIV/ADIS comprehensive response information management system. Their plasma samples were used for RNA gene extraction, amplification, sequencing and genotyping. Coharan-Armitage trend test was used to analyze the ratio trend of genetic subtypes and phylogenetic clusters of HIV and Wilcoxon Rank Sum Test was used to compare the first CD(4)(+)T cell counts (CD(4)) of the different subtype HIV infected patients. Results: A total of 1 877 newly diagnosed HIV infected patients were included in the study. From 1998 to 2012, the proportions of CRF01_AE and CRF01_AE (Cluster 1) increased from 78.4% (76/97) to 91.5% (1 441/1 574), from 63.9% (62/97) to 74.0% (1 164/1 574), and the proportion of CRF07_BC decreased from 17.5% (17/97) to 4.6% (72/1 574), respectively (Z=4.632, P<0.001; Z=2.455, P=0.014; Z=-5.943, P<0.001). The median and interquartile range of the first CD(4) of the patients infected with subtype CRF01_AE (Cluster 1), CRF01_AE (Cluster 2), CRF07_BC and CRF08_BC were 230 (83-375), 215 (48-351), 365 (254-503) and 334 (206-479) cell/μl, respectively. The first CD(4) levels of the patients infected with subtype CRF01_AE (Cluster 1) or CRF01_AE (Cluster 2) were significantly lower than those of CRF07_BC (Z=-4.795, P<0.001; Z=-4.238, P<0.001). Conclusion: The genetic subtypes of HIV were mainly CRF01_AE in newly diagnosed HIV-infected patients and this subtype proportion was in increase and the first CD(4) levels of the patients were low in Liuzhou during 1998 to 2012.

[Impact of HIV and Mycobacterium tuberculosis co-infection on related mortality]

Objective: To understand the impact of HIV and Mycobacterium tuberculosis (MTB) co-infectious (HIV/MTB) on related mortality in Guangxi Zhuang Autonomous Region, provide evidence for the development of a better HIV/MTB co-infection control and prevention program. Methods: A multiple cross-systems check (MCSC) approach was used to confirm the HIV/MTB co-infection individuals on data related to treatment, follow-up, epidemiological comprehensive and Tuberculosis (TB) special report system. Social demography characteristics, incidence of TB among HIV positive individuals, HIV incidence among MTB infection persons etc., were described. We compared the mortalities and related risks between HIV/MTB co-infection and mono HIV positive individuals as well as between the HIV/MTB co-infection and mono MTB infection persons, using both the Chi Square test and the Cox's proportional hazard regression model (Cox). Results: Reported data showed that the incidence of MTB co-infection in the HIV cohort was 17.72% (2 533/14 293), while HIV incidence in the TB patients was 5.57% (2 351/42 205), respectively. The mortality of HIV/MTB co-infection in the HIV/AIDS cohort was 15.16% (384/2 533) within one-year of observation and was significantly higher than the mortality (13.63%,1 603/11 760) of mono HIV positive individuals (P<0.000 1). The percentage of the HIV/AIDS death cases was 19.33% (384/1 987) who registered and died in the 2011 calendar year were caused by MTB co-infection. Among all the HIV/MTB co-infection patients who had been identified from the HIV cohort, 60.05% (1 521/2 533) had initiated ART, 15.48% (392/2 533) had been cured for TB and 27.48% (696/2 533) had been under complete TB regimen. Among the confirmed HIV/MTB cases from the TB cohort, the cure rate of TB was 19.70% (463/2 351) and the percentage of completed TB regimen was 37.26% (876/2 351). The percentage of the individuals whose CD(4)(+) T lymphocyte cells count appeared less than 200 cell/μl was 64.13% (785/1 224), upon the HIV diagnoses were made. Compared with individuals who were under mono HIV infection, the mortality risk on HIV/MTB co-infection was 1.17 times higher during the five-year observation period, then the patients with only mono MTB infection and the mortality risk in patients with HIV/MTB co-infection was 25.68 times higher under the 12-month observation period. Conclusions: Both the incidence and mortality of HIV/MTB appeared high in Guangxi, with mortality and the risk of mortality in the HIV/MTB co-infection group significantly higher than that in both the HIV mono infection and the MTB mono infections groups. Both the rate of antiretroviral treatment coverage and the cure rate of TB treatment should be increased in no time as well as the capability of early TB case-finding among people living with HIV.

Rho-kinase/AMPK axis regulates hepatic lipogenesis during overnutrition

Obesity is a major risk factor for developing nonalcoholic fatty liver disease (NAFLD). NAFLD is the most common form of chronic liver disease and is closely associated with insulin resistance, ultimately leading to cirrhosis and hepatocellular carcinoma. However, knowledge of the intracellular regulators of obesity-linked fatty liver disease remains incomplete. Here we showed that hepatic Rho-kinase 1 (ROCK1) drives obesity-induced steatosis in mice through stimulation of de novo lipogenesis. Mice lacking ROCK1 in the liver were resistant to diet-induced obesity owing to increased energy expenditure and thermogenic gene expression. Constitutive expression of hepatic ROCK1 was sufficient to promote adiposity, insulin resistance, and hepatic lipid accumulation in mice fed a high-fat diet. Correspondingly, liver-specific ROCK1 deletion prevented the development of severe hepatic steatosis and reduced hyperglycemia in obese diabetic (ob/ob) mice. Of pathophysiological significance, hepatic ROCK1 was markedly upregulated in humans with fatty liver disease and correlated with risk factors clustering around NAFLD and insulin resistance. Mechanistically, we found that hepatic ROCK1 suppresses AMPK activity and a ROCK1/AMPK pathway is necessary to mediate cannabinoid-induced lipogenesis in the liver. Furthermore, treatment with metformin, the most widely used antidiabetes drug, reduced hepatic lipid accumulation by inactivating ROCK1, resulting in activation of AMPK downstream signaling. Taken together, our findings establish a ROCK1/AMPK signaling axis that regulates de novo lipogenesis, providing a unique target for treating obesity-related metabolic disorders such as NAFLD.

Saturated fatty acids-induced miR-424-5p aggravates insulin resistance via targeting insulin receptor in hepatocytes

The excessive intake of saturated fatty acids (SFA) causes obesity and liver steatosis, which are major risk factors for insulin resistance and type 2 diabetes. Although the expression of certain microRNAs (miRNAs) targeting the insulin signaling molecules are regulated aberrantly in SFA-induced obesity, their implications on hepatic insulin resistance are largely unknown. This study examined the associations of miR-424-5p, which is induced by SFA, with the development of insulin resistance. SFA palmitate (PA)-treated HepG2 cells and high fat diet (HFD)-induced obese mouse livers showed an impairment of insulin signaling due to a significant decrease in INSR and IRS-1 expression. Based on expression profiling and qRT-PCR analysis, miR-424-5p, which presumably targets the 3'UTR of INSR, was upregulated in both PA-treated HepG2 cells and the liver of HFD-fed mice. miR-424-5p was found to target the 3'UTR of INSR directly and downregulated INSR expression at the post-transcriptional step. Furthermore, the overexpression of miR-424-5p suppressed INSR expression significantly, leading to impaired insulin signaling and glycogen synthesis in hepatocytes. A novel mechanism for how SFA-induced miR-424-5p impairs insulin signaling through the targeting of INSR is reported. In addition, the crucial role and underlying mechanism of miR-424-5p in the obesity-induced hepatic insulin resistance is explained.

Development of an efficient gas kinetic scheme for simulation of two-dimensional incompressible thermal flows

In this work, an efficient gas kinetic scheme is presented for simulation of two-dimensional incompressible thermal flows. In the scheme, the macroscopic governing equations for mass, momentum, and energy conservation are discretized by the finite volume method and the numerical fluxes at the cell interface are reconstructed by the local solution of the Boltzmann equation. To compute these fluxes, two distribution functions are involved. One is the circular function, which is used to calculate the numerical fluxes of mass and momentum equations. Due to the incompressible limit, the circle at the cell interface can be approximately considered to be symmetric so that the expressions for the conservative variables and numerical fluxes at the cell interface can be given explicitly and concisely. Another one is the D2Q4 model, which is utilized to compute the numerical flux of the energy equation. By following the process for derivation of numerical fluxes of mass and momentum equations, the numerical flux of the energy equation can also be given explicitly. The accuracy, efficiency, and stability of the present scheme are validated by simulating several thermal flow problems. Numerical results showed that the present scheme can provide accurate numerical results for incompressible thermal flows at a wide range of Rayleigh numbers with less computational cost than that needed by the thermal lattice Boltzmann flux solver (TLBFS), which has been proven to be more efficient than the thermal lattice Boltzmann method (TLBM).

Spirodela polyrhiza extract modulates the activation of atopic dermatitis-related ion channels, Orai1 and TRPV3, and inhibits mast cell degranulation

CONTEXT

Spirodela polyrhiza (L.) Schleid. (Lemnaceae), Spirodelae Herba (SH), has been known to relieve inflammation, urticaria and skin symptoms including pruritus, eczema and rash.

OBJECTIVE

The effects of SH extract on two calcium ion channels, Orai1 and TRPV3, and their potential as novel therapeutics for atopic dermatitis (AD) were investigated. The regulatory role of Orai1 on mast cell degranulation was evaluated.

MATERIALS AND METHODS

The dried leaves of SH were extracted by 70% methanol. Effects of SH extract (100 μg/mL) in an HEK293T cell line overexpressing human Orai1 or TRPV3 were assessed. Ion channel modulation in transfected HEK293T cells was measured using a conventional whole-cell patch-clamp technique. IgE-antigen complex-stimulated mast cell degranulation was measured by β-hexosaminidase assay with morphological observation after treatment with 20, 50 and 100 μg/mL SH extract.

RESULTS

SH extract (100 μg/mL) significantly inhibited Orai1 activity (63.8 ± 0.97%) in Orai1-STIM1 co-overexpressed HEK293T cells. SH extract significantly increased TRPV3 activity (81.29 ± 0.05% at -100 mV) compared with the positive control 2-APB (100 μM), which induced full activation. SH extract inhibited degranulation in IgE-antigen complex-stimulated RBL-2H3 mast cells by decreasing β-hexosaminidase activity (3.14 ± 0.03, 2.56 ± 0.12 and 2.29 ± 0.08 mU/mg, respectively).

CONCLUSION

Our results suggested that SH extract could treat abnormal skin barrier pathologies in AD through modulation of the activities of the calcium ion channels Orai1 and TRPV3 and inhibition of mast cell degranulation. This is the first report of an herbal effect on the modulation of ion channels associated with skin barrier disruption in AD pathogenesis.

Data on the effect of miR-15b on the expression of INSR in murine C2C12 myocytes

The ectopic expression of miR-15b is linked causally to impaired insulin signaling in human HepG2 hepatocytes through the suppression of INSR (Yang et al., 2015) [1]. In this data article, we further examined the effect of miR-15b on insulin signaling in a murine skeletal muscle cells, C2C12 myocytes. Although the 3’UTR of mouse INSR mRNA has an appropriate binding site for miR-15b based on TargetScan analysis, the ectopic expression of miR-15b did not suppress the expression and insulin-stimulated phosphorylation of insulin signaling intermediates in C2C12 myocytes. A more detailed understanding of the effects of miR-15b on hepatic insulin resistance can be found in “Obesity-induced miR-15b is linked causally to the development of insulin resistance through the repression of the insulin receptor in hepatocytes” (Yang et al., 2015) [1].

Data on the expression and insulin-stimulated phosphorylation of IRS-1 by miR-96 in L6-GLUT4myc myocytes

Diets containing a high saturated fatty acid (SFA) increase the risk of metabolic diseases, and microRNAs (miRNAs) induced by SFA have been implicated in the pathogenesis of insulin resistance and type 2 diabetes. In a previous report, miR-96 is found to be upregulated by SFA and involved in the suppression of insulin signaling intermediates, leading to insulin resistance in hepatocytes (Yang et al., 2016) [1]. This article presents the accompanying data collected from L6-GLUT4myc myocytes to determine the effects of miR-96 on insulin signaling in skeletal muscle cells. The transfection of miR-96 decreased the expression of IRS-1 in myocytes. Accordingly, miR-96 inhibited the insulin-stimulated phosphorylation of IRS-1, which led to an impairment of insulin signaling. More detailed analysis and understanding of the roles of miR-96 in diet-induced insulin resistance can be found in "Induction of miR-96 by dietary saturated fatty acids exacerbates hepatic insulin resistance through the suppression of INSR and IRS-1" (Yang et al., 2016) [1].

[Loss of BRCA associated protein 1 expression in malignant mesothelioma and its diagnostic application]

Objective: To investigate the expression of BRCA-associated protein 1 (BAP1) in malignant mesothelioma, non-small cell lung cancer and carcinosarcoma, and its application in the differential diagnosis. Methods: Twenty-two cases of malignant mesothelioma including 17 epithelioid type, 2 sarcomatoid type and 3 biphasic type were collected.As the study control, 80 non-small cell lung cancers infringement pleural membrane(including 40 lung adenocarcinomas and 40 lung squamous cell carcinomas) and 15 carcinosarcomas were included. BAP1 expression was detected using immunohistochemical method. A differential diagnosis antibody panel, including calretinin, WT1, CK5/6, D2-40, CAM5.2, CEA, TTF1, Napsin A, p63 and p40 was tested in all cases. Results: All 80 cases of non-small cell lung cancer and 15 cases of carcinosarcoma were BAP1 positive. In contrast, 64% (14/22) of malignant mesotheliomas lost BAP1 expression (P<0.01). Addition of BAP1 to the mesothelioma marker panel, the diagnostic accuracy of malignant mesothelioma was enhanced to 93%. Focal expression of BAP1 in tumors suggested multiclonal evolution of mesothelioma. Conclusions: Loss of BAP1 expression helps to confirm the diagnosis of malignant mesothelioma whereas all non-small cell lung cancer expresses BAP1. It is therefore recommended that BAP1 can be used in conjunction with other immunohistochemical markers to improve the diagnostic accuracy of malignant mesothelioma.

Dataset on the identification of differentially expressed genes by annealing control primer-based PCR in mitochondrial DNA-depleted myocytes

Changes in the mitochondrial DNA (mtDNA) content are believed to initiate a stress signal that leads to alterations in nuclear gene expression. This article presents data on the identification of nuclear genes that are expressed differentially in response to changes in the mtDNA content in myocytes using annealing controlled primers (ACP)-based PCR technology. The data obtained from L6 GLUT4myc myocytes showed that a total of 19 ACPs produced differentially expressed PCR amplicons in the mtDNA-depleted myocytes. Among those, 13 amplicons were cloned, sequenced, and identified successfully based on the GenBank database. To validate the efficacy of ACP-based PCR analysis, three differentially expressed genes (DEG10, 22 and 26) were confirmed by PCR using the specific primers. The further analysis and detailed results of DEG22 and its functional significance can be found in "C1q tumor necrosis factor alpha-related protein isoform 5 is increased in mitochondrial DNA-depleted myocytes and activates AMP-activated protein kinase." [1].

Incorporating an immersed boundary method to study thermal effects of vascular systems during tissue cryo-freezing

In this paper, the three-dimensional thermal effects of a clinically-extracted vascular tissue undergoing cryo-freezing are numerically investigated. Based on the measured experimental temperature field, the numerical results of the Pennes bioheat model combined with the boundary condition-enforced immersed boundary method (IBM) agreed well with experimental data with a maximum temperature discrepancy of 2.9°C. For simulating the temperature profile of a tumor sited in a dominantly vascularized tissue, our model is able to capture with ease the thermal effects at specified junctions of the blood vessels. The vascular complexity and the ice-ball shape irregularity which cannot be easily quantified via clinical experiments are also analyzed and compared for both two-dimensional and three-dimensional settings with different vessel configurations and developments. For the three-dimensional numerical simulations, a n-furcated liver vessels model from a three-dimensional segmented volume using hole-making and subdivision methods is applied. A specific study revealed that the structure and complexity of the vascular network can markedly affect the tissue's freezing configuration with increasing ice-ball irregularity for greater blood vessel complexity.

Induction of miR-96 by Dietary Saturated Fatty Acids Exacerbates Hepatic Insulin Resistance through the Suppression of INSR and IRS-1

Obesity is defined as the excessive accumulation of body fat that ultimately leads to chronic metabolic diseases. Diets rich in saturated fatty acids (SFA) exacerbate obesity and hepatic steatosis, which increase the risk of hepatic insulin resistance and type 2 diabetes (T2DM). Although microRNAs (miRNAs) play an important role in a range of biological processes, the implications of SFA-induced miRNAs in metabolic dysregulation, particularly in the pathogenesis of hepatic insulin resistance, are not well understood. This study investigated the implications of miR-96, which is induced strongly by SFA, in the development of hepatic insulin resistance. The liver of HFD mice and the palmitate-treated hepatocytes exhibited an impairment of insulin signaling due to the significant decrease in INSR and IRS-1 expression. According to expression profiling and qRT-PCR analysis of the miRNAs, the expression level of miR-96 was higher in hepatocytes treated with palmitate. Moreover, miR-96 was also upregulated in the liver of HFD mice. Interestingly, miR-96 targeted the 3'UTRs of INSR and IRS-1 directly, and repressed the expression of INSR and IRS-1 at the post-transcriptional level. Accordingly, the overexpression of miR-96 was found to cause a significant decrease in INSR and IRS-1 expression, thereby leading to an impairment of insulin signaling and glycogen synthesis in hepatocytes. These results reveal a novel mechanism whereby miR-96 promotes the pathogenesis of hepatic insulin resistance resulted from SFA or obesity.

Data for differentially expressed microRNAs in saturated fatty acid palmitate-treated HepG2 cells

Certain microRNAs (miRNAs) targeting the molecules in the insulin signaling cascades are dysregulated by saturated fatty acids (SFA), which can lead to insulin resistance and type 2 diabetes. This article reports the accompanying data collected using miRNAs microarrays to identify the changes in miRNA expression in HepG2 cells treated with SFA palmitate. Differentially expressed miRNA analyses in HepG2 cells showed that a range of upregulated (>1.5-fold) or downregulated (<0.5-fold) miRNAs. Further extensive insights into the implications of miRNAs, particularly miR-1271, in HepG2 cells can be found in "MiR-1271 upregulated by saturated fatty acid palmitate provokes impaired insulin signaling by repressing INSR and IRS-1 expression in HepG2 cells" (W.M. Yang, K.H. Min, W. Lee, 2016) [1].

[Mechanism of RhoA/Rho-kinase signal pathway-induced erectile dysfunction in hyperlipidemic rats]

OBJECTIVE

To investigate the expression of RhoA/Rho-kinase (ROCK) in penile corpus cavernosum smooth muscles in rats of hyperlipidemia-induced erectile dysfunction and its molecular mechanism.

METHODS

Forty male Sprague-Dawley rats were randomly divided into control and experimental groups using a random number table. Rats in the control group (n=20) were fed with regular diet for 24 weeks and those in the experimental group (n=20) with high-fat diet for the same period of time. The serum lipids profile was detected before and after the diet treatment. The ratio of intracavernosal pressure (ΔICP)/mean arterial pressure (MAP) was measured, and Western blot was used to detect the expression of total RhoA, ROCK1, and ROCK2 in penile corpus cavernosum smooth muscles, and RhoA protein in cell membrane and cytoplasm of smooth muscles after 24 weeks.

RESULTS

After 24 weeks, the levels of cholesterol, triglyceride, and low-density lipoprotein were significantly higher in the experimental group compared with those before diet treatment and the control group (all P<0.01). ΔICP/MAP in the experimental group was greatly lower than in the control group (P<0.01). The protein expression of ROCK2 in penile corpus cavernosum smooth muscles was higher in the experimental group than in the control group (0.77±0.10 vs 0.27±0.08, P<0.01) after 24 weeks, while no statistically significant differences were observed in total RhoA and ROCK 1 protein expression between the two groups (both P>0.05). RhoA expression in cytoplasm was lower in the experimental than in the control group (1.66±0.09 vs 1.79±0.15, P<0.05). The ratio of RhoA expression in menmbrane/cytoplasm was higher in the experimental than in the control group (0.33±0.09 vs 0.26±0.07, P<0.05).

CONCLUSION

Up-regulation of RhoA/ROCK may be involved in hyperlipidemia-induced erectile dysfunction in rats.

C1q tumor necrosis factor α-related protein isoform 5 attenuates palmitate-induced DNA fragmentation in myocytes through an AMPK-dependent mechanism

This article reports the data for the effects of C1q tumor necrosis factor α-related protein isoform 5 (CTRP5) on the palmitate-induced apoptosis in myocytes. The data obtained from in vitro cultured myocytes shows that the cellular treatment with the globular domain of CTRP5 (gCTRP5) significantly inhibits the palmitate-induced MTT reduction, caspase-3 activation, and DNA fragmentation in a time-dependent manner. The data presented in this article also shows that AraA, an inhibitor of AMPK, almost completely abolished the protective effect of gCTRP5 on the DNA fragmentation induced by palmitate in myocytes. Interpretation of our data and further extensive insights into the protective role of CTRP5 in palmitate-induced apoptosis in myocytes can be found in Yang and Lee (2014) [1].

Obesity-induced miR-15b is linked causally to the development of insulin resistance through the repression of the insulin receptor in hepatocytes

SCOPE

Obesity increases intracellular lipid accumulation in key tissues or organs, which often leads to metabolic dysfunction and insulin resistance. Diets rich in saturated fatty acid (SFA) exacerbate obesity and hepatic steatosis, which accentuate the risk of insulin resistance and type 2 diabetes (T2DM). Although microRNAs (miRNAs) play a critical role in the regulation of gene expression, the implication of obesity-induced miRNAs in metabolic disorders particularly in the development of insulin resistance is largely unknown. Here, we investigated the implication of miR-15b, which is induced by SFA palmitate or obesity, in hepatic insulin resistance.

METHODS AND RESULTS

Diet-induced obesity (DIO) in mice developed hyperglycemia and insulin resistance, accompanying with a reduction of insulin receptor (INSR) expression. Palmitate impaired insulin signaling as well as a decrease of INSR in hepatocytes. The expression of miR-15b was upregulated by DIO or palmitate in hepatocytes. Furthermore, the overexpression of miR-15b suppressed the protein expression of INSR through targeting INSR 3' untranslated region directly, resulting in an impairment of the insulin signaling and glycogen synthesis in hepatocytes.

CONCLUSION

These results unveil a novel mechanism whereby miR-15b is linked causally to the pathogenesis of hepatic insulin resistance in SFA-induced obesity.

CTRP5 ameliorates palmitate-induced apoptosis and insulin resistance through activation of AMPK and fatty acid oxidation

Lipotoxicity resulting from a high concentration of saturated fatty acids is closely linked to development of insulin resistance, as well as apoptosis in skeletal muscle. CTRP5, an adiponectin paralog, is known to activate AMPK and fatty acid oxidation; however, the effects of CTRP5 on palmitate-induced lipotoxicity in myocytes have not been investigated. We found that globular domain of CTRP5 (gCTRP5) prevented palmitate-induced apoptosis and insulin resistance in myocytes by inhibiting the activation of caspase-3, reactive oxygen species accumulation, and IRS-1 reduction. These beneficial effects of gCTRP5 are mainly attributed to an increase in fatty acid oxidation through phosphorylation of AMPK. These results provide a novel function of CTRP5, which may have preventive and therapeutic potential in management of obesity, insulin resistance, and type 2 diabetes mellitus.

Induction of miR-29a by saturated fatty acids impairs insulin signaling and glucose uptake through translational repression of IRS-1 in myocytes

MicroRNAs have been shown to play an important role in insulin signaling but their biological function in insulin resistance induced by saturated fatty acids (SFA) remains largely unknown. Here, we report that SFA palmitate and high fat diet (HFD) significantly increase expression of miR-29a in myocytes. miR-29a targets IRS-1 3'UTR directly and represses IRS-1 expression at the translational level. Furthermore, the ectopic expression of miR-29a impairs insulin signaling and glucose uptake in myocytes through a substantial decrease in IRS-1. These findings suggest that the up-regulation of miR-29a by SFA is causally related to the development of insulin resistance in myocytes.

The induction of miR-96 by mitochondrial dysfunction causes impaired glycogen synthesis through translational repression of IRS-1 in SK-Hep1 cells

MicroRNA (miRNA) is a class of endogenous small noncoding RNA that negatively regulates gene expression at the post-transcriptional level and plays an important role in the pathogenesis of various diseases. However, the identity and role of miRNAs involved in the development of insulin resistance resulting from mitochondrial dysfunction are largely unknown. In this study, mitochondrial dysfunction by genetic or metabolic inhibition induced an impairment of insulin signaling in SK-Hep1 cells via a reduction in the expression of IRS-1 protein. Significant up-regulation of miR-96, which was presumed to target IRS-1 3'UTR, was found in SK-Hep1 cells with mitochondrial dysfunction. Using reporter gene assay we confirmed that miR-96 authentically targeted IRS-1 3'UTR. Furthermore, the ectopic expression of miR-96 caused a substantial decrease in IRS-1 protein expression, and a consequent impairment in insulin signaling. These findings suggest that the up-regulation of miR-96 by mitochondrial dysfunction contributes to the development of insulin resistance by targeting IRS-1 in SK-Hep1 cells.

TRAV gene expression in PBMCs and TILs in patients with breast cancer analyzed by a DNA melting curve (FQ-PCR) technique for TCR α chain CDR3 spectratyping

PURPOSE

To explore the expression of the TRAV gene in peripheral blood mononuclear cells (PBMCs) and in tumor-infiltrating lymphocytes (TILs) in the patients with breast cancer using a DNA melting curve (FQ-PCR) technique for T cell receptor (TCR) alpha chain CDR3 spectratyping. Peripheral blood samples and tissue samples were obtained from thirty breast cancer patients. Total RNA was extracted from PBMCs and tumor tissues and then reverse transcribed into cDNA. FQ-PCR was used to amplify the human TCR alpha chain CDR3 region with the primers to the TRAV and TRAC genes. TCR alpha chain CDR3 spectratyping and partial CDR3 sequencing were used to determine use of TRAV gene product in T cell responses. TCR alpha CDR3 spectratyping showed preferential usage of certain TRAV genes in the PBMCs and TILs of all patients with breast cancer. The frequencies of TRAV1.1, TRAV9, and TRAV29 exceeded 30% in PBMCs and the frequencies of TRAV1.1 and TRAV22 exceeded 30% in TILs. More than three quarters of the patients (23/30) overexpressed the same gene in both PBMCs and TILs; for example, patient-1 highly expressed TRAV9 in the PBMCs and TILs. Patients with positive or negative tumor markers of estrogen receptor (ER), progesterone receptor (PR), pS2, C-erbB-2, nm23, P53, and Ki-67 showed no significant common TRAV gene expression, but some TRAV gene preferential usage frequencies exceeded 20%. For example, five of seven patients positive for ER had high levels of expression of TRAV1.1 and TRAV3. Finally, the amino acid sequence of TCR CDR3 region showed some common motifs in some of the patients.

CONCLUSIONS

TRAV gene expression was complex and diverse in the patients with breast cancer. The TRAV gene usage may be closely related to the diversity of breast tumor antigens and the differential immune responses observed in individual patients. Research into the immunological mechanism of T cells may provide guidance for individual T cell-directed therapy for breast cancer.

Age-related changes in kallikreins-kinins system in rat corpus cavernosum

Many factors, such as nitric oxide synthase, androgen and growth factors, can regulate the tone of corpus cavernosum (CC) smooth muscle with an age-related tendency. It has been shown that the active metabolites of kallikreins-kinins system (KKS), including bradykinin, Lys-BK and Met-Lys-BK, can also relax the CC smooth muscle significantly in vitro. Our aim was to evaluate the specific association between KKS and age in rat CC. CC and thoracic aorta were isolated from rats at postnatal weeks (PW) of 2, 8, 12, 20, 30, 40 and 60, respectively. Tissue kallikrein-I (KLKI) and kinin B2 receptor (B2R) mRNA in CC and thoracic aorta were detected by real-time polymerase chain reaction (PCR). Protein expression of KLKI and B2R were determined with immunofluorescence in situ and Western blot. Real-time PCR, immunofluorescence in situ and Western blot all demonstrated that the age-related changes in expression of KLKI were similar between the CC and thoracic aorta. It significantly increased with age from PW2 to PW30, reached the peak at PW30 and then declined gradually. However, there was no statistically significant difference among PW30, PW40 and PW60. Similarly, the expression of B2R increased gradually with age reached and remained at the peak during adult stages and no significant differences were found among PW20, PW30 and PW40; then, it decreased significantly at PW60. The changes in the expression of B2R in CC and age-matched aorta were similar except that it was significantly less than that in the aorta at PW60. The expression of KLKI and B2R changed in an age-dependent pattern in rat CC and have a tendency to decline during ageing, which is of the same tendency as reported for erection capacity in ageing males and suggests why ageing is an independent predictor of ED, to some extent.

Transient expression of iron transport proteins in the capillary of the developing rat brain

Iron is essential for normal brain function and its uptake in the developing rat brain peaks during the first two weeks after birth, prior to the formation of the blood–brain barrier (BBB). The first step of iron transport from the blood to the brain is transferrin receptor (TfR)-mediated endocytosis in the capillary endothelial cells. However, the subsequent step from the endothelium into interstitium has not been fully described. The goal of this study was to examine the expression of iron transport proteins by immunodetection and RT–PCR in the developing rat brain. Tf and TfR are transiently expressed in perivascular NG2+ cells of the capillary wall during the early postnatal weeks in the rat brain. However, MTP-1 and hephaestin were expressed in endothelial cells, but not in the NG2+ perivascular cells. Immunoblot analysis for these iron transfer proteins in the developing brain generally confirmed the immunochemical findings. Furthermore, the expression of Tf and TfR in the blood vessels precedes its expression in oligodendrocytes, the main iron-storing cells in the vertebrate brain. RT–PCR analysis for the primary culture of endothelial cells and pericytes revealed that Tf and TfR were highly expressed in the pericytes while MTP-1 and hephaestin were expressed in the endothelial cells. The specific expression of Tf and TfR in brain perivascular cells and MTP-1 and hephaestin in endothelial cells suggest the possibility that trafficking of elemental iron through perivascular cells may be instrumental in the distribution of iron in the developing central nervous system.

Tamsulosin treatment of chronic non-bacterial prostatitis

The efficacy of tamsulosin in the treatment of chronic non-bacterial prostatitis was evaluated in a randomized clinical observation of 105 male outpatients conducted for 90 days. Patients were randomly divided into five groups (n = 21 per group) according to prostatitis type IIIA or IIIB and therapy regimens (tamsulosin, levofloxacin, or tamsulosin plus levofloxacin combination therapy). National Institutes of Health Chronic Prostatitis Symptom Index scores, expressed prostatic massage test and urodynamic urethral pressure and urethral closure pressure tests were performed to evaluate clinical efficacy of the treatments. Scores for pain, urinary symptoms and quality of life were significantly improved by days 45 and 90 after all treatments in both prostatitis categories. Improvements in symptom scores in the combined treatment group were significantly superior to those in the single treatment groups. Tamsulosin and levofloxacin are both effective in the treatment of, and may have an additive effect in, the treatment of non-bacterial prostatitis.

Yin-Yang 1 activates interleukin-4 gene expression in T cells

Interleukin-4 (IL-4) is a multifunctional cytokine that plays an important role in immune and inflammatory responses. Expression of the IL-4 gene is tightly controlled at the level of gene transcription by both positive and negative regulatory elements in the IL-4 promoter. Several constitutive nuclear factors have been identified that can interact with IL-4 promoter elements in DNA binding assays. Here we report that the zinc-finger protein YY-1 (Yin-Yang 1) can bind to multiple elements within the human IL-4 promoter. Cotransfection of Jurkat T cells with different IL-4 promoter/reporter constructs together with expression vectors encoding antisense, wild-type, or zinc finger-deleted mutant YY-1 suggested that YY-1 enhanced IL-4 promoter activity in a DNA-binding domain-dependent manner. Site-directed mutagenesis revealed that a proximal YY-1-binding site, termed Y0 ((-59)TCATTTT(-53)), was essential for YY-1-driven IL-4 promoter activity. In addition, cotransfected YY-1 enhanced both IL-4 promoter activity and endogenous IL-4 gene expression in nontransformed peripheral blood T cells. Thus, YY-1 positively regulates IL-4 gene expression in lymphocytes.

Histone deacetylase activity represses gamma interferon-inducible HLA-DR gene expression following the establishment of a DNase I-hypersensitive chromatin conformation

Expression of the retinoblastoma tumor suppressor protein (Rb) is required for gamma interferon (IFN-gamma)-inducible major histocompatibility complex class II gene expression and transcriptionally productive HLA-DRA promoter occupancy in several human tumor cell lines. Treatment of these Rb-defective tumor cell lines with histone deacetylase (HDAC) inhibitors rescued IFN-gamma-inducible HLA-DRA and -DRB mRNA and cell surface protein expression, demonstrating repression of these genes by endogenous cellular HDAC activity. Additionally, Rb-defective, transcriptionally incompetent tumor cells retained the HLA-DRA promoter DNase I-hypersensitive site. Thus, HDAC-mediated repression of the HLA-DRA promoter occurs following the establishment of an apparent nucleosome-free promoter region and before transcriptionally productive occupancy of the promoter by the required transactivators. Repression of HLA-DRA promoter activation by HDAC activity likely involves a YY1 binding element located in the first exon of the HLA-DRA gene. Chromatin immunoprecipitation experiments localized YY1 to the HLA-DRA gene in Rb-defective tumor cells. Additionally, mutation of the YY1 binding site prevented repression of the promoter by HDAC1 and partially prevented activation of the promoter by trichostatin A. Mutation of the octamer element also significantly reduced the ability of HDAC1 to confer repression of inducible HLA-DRA promoter activation. Treatment of Rb-defective tumor cells with HDAC inhibitors greatly reduced the DNA binding activity of Oct-1, a repressor of inducible HLA-DRA promoter activation. These findings represent the first evidence that HDAC activity can repress IFN-gamma-inducible HLA class II gene expression and also demonstrate that HDAC activity can contribute to promoter repression following the establishment of a DNase I-hypersensitive chromatin conformation.

Regulation of transcription factor YY1 by acetylation and deacetylation

YY1 is a sequence-specific DNA-binding transcription factor that has many important biological roles. It activates or represses many genes during cell growth and differentiation and is also required for the normal development of mammalian embryos. Previous studies have established that YY1 interacts with histone acetyltransferases p300 and CREB-binding protein (CBP) and histone deacetylase 1 (HDAC1), HDAC2, and HDAC3. Here, we present evidence that the activity of YY1 is regulated through acetylation by p300 and PCAF and through deacetylation by HDACs. YY1 was acetylated in two regions: both p300 and PCAF acetylated the central glycine-lysine-rich domain of residues 170 to 200, and PCAF also acetylated YY1 at the C-terminal DNA-binding zinc finger domain. Acetylation of the central region was required for the full transcriptional repressor activity of YY1 and targeted YY1 for active deacetylation by HDACs. However, the C-terminal region of YY1 could not be deacetylated. Rather, the acetylated C-terminal region interacted with HDACs, which resulted in stable HDAC activity associated with the YY1 protein. Finally, acetylation of the C-terminal zinc finger domain decreased the DNA-binding activity of YY1. Our findings suggest that in the natural context, YY1 activity is regulated through intricate mechanisms involving negative feedback loops, histone deacetylation, and recognition of the cognate DNA sequence affected by acetylation and deacetylation of the YY1 protein.

The growth suppressor PML represses transcription by functionally and physically interacting with histone deacetylases

The growth suppressor promyelocytic leukemia protein (PML) is disrupted by the chromosomal translocation t(15;17) in acute promyelocytic leukemia (APL). PML plays a key role in multiple pathways of apoptosis and regulates cell cycle progression. The present study demonstrates that PML represses transcription by functionally and physically interacting with histone deacetylase (HDAC). Transcriptional repression mediated by PML can be inhibited by trichostatin A, a specific inhibitor of HDAC. PML coimmunoprecipitates a significant level of HDAC activity in several cell lines. PML is associated with HDAC in vivo and directly interacts with HDAC in vitro. The fusion protein PML-RARalpha encoded by the t(15;17) breakpoint interacts with HDAC poorly. PML interacts with all three isoforms of HDAC through specific domains, and its expression deacetylates histone H3 in vivo. Together, the results of our study show that PML modulates histone deacetylation and that loss of this function in APL alters chromatin remodeling and gene expression. This event may contribute to the development of leukemia.

Effect of copper aspirinate on contraction of isolated rabbit aortic strips

AIM

To investigate the effect of copper aspirinate on contraction of vascular smooth muscle.

METHODS

Isolated rabbit aortic strips, including intact endothelium strips and endothelial cell-denuded aortic strips, were suspended in modified Krebs'solution to determine effects of copper aspirinate on the contraction induced by norepinephrine (NE), KCl, and CaCl2, while CuSO4, aspirin, and vehicle were used as controls.

RESULTS

Copper aspirinate possessed antagonistic effect on contraction of rabbit aortic strips induced by NE with an IC50 value of 31 nmol/L, while CuSO4 had much l ess antagonistic effect with an IC50 value of 0.29 micromol/L, and aspirin did not work in the same preparation. No effect of copper aspirinate were found on the contraction induced by KCl and CaCl2. Effects on endothelial cell denuded aortic strips were similar to those in the normal aortic strips.

CONCLUSION

Copper aspirinate possessed different effects from aspirin and CuSO4 on vascular smooth muscles. It inhibited contraction induced by NE with an activity stronger than CuSO4 at the same Cu2+ concentration, this action might be due to blockade of the receptor-operated Ca2+ channels, and it might not be linked to the endothelium.

Histone deacetylase interacts directly with DNA topoisomerase II

Histone deacetylases (HDACs) modify nucleosomal histones, have a key role in the regulation of gene transcription, and may be involved in cell-cycle regulation, differentiation and human cancer. Purified recombinant human HDAC1 protein was used to screen a cDNA expression library, and one of the clones identified encoded DNA topoisomerase II (Topo II), an enzyme known to have a role in transcriptional regulation and chromatin organization. Coimmunoprecipitation experiments indicate that HDAC1 and HDAC2 are associated with Topo II in vivo under normal physiological conditions. Complexes containing Topo II possess HDAC activities, and complexes containing HDAC1 or HDAC2 possess Topo II activities. HDAC and Topo II modify each other's activity in vitro and in vivo. Our results indicate the existence of a functionally coupled complex between these two enzymes and offer insights into the potential mechanisms of action of both enzymes.

Histone deacetylases specifically down-regulate p53-dependent gene activation

p53, the most commonly mutated gene in cancer cells, directs cell cycle arrest or induces programmed cell death (apoptosis) in response to stress. It has been demonstrated that p53 activity is up-regulated in part by posttranslational acetylation. In agreement with these observations, here we show that mammalian histone deacetylase (HDAC)-1, -2, and -3 are all capable of down-regulating p53 function. Down-regulation of p53 activity by HDACs is HDAC dosage-dependent, requires the deacetylase activity of HDACs, and depends on the region of p53 that is acetylated by p300/CREB-binding protein (CBP). These results suggest that interactions of p53 and HDACs likely result in p53 deacetylation, thereby reducing its transcriptional activity. In support of this idea, GST pull-down and immunoprecipitation assays show that p53 interacts with HDAC1 both in vitro and in vivo. Furthermore, a pre-acetylated p53 peptide was significantly deacetylated by immunoprecipitated wild type HDAC1 but not deacetylase mutant. Also, co-expression of HDAC1 greatly reduced the in vivo acetylation level of p53. Finally, we report that the activation potential of p53 on the BAX promoter, a natural p53-responsive system, is reduced in the presence of HDACs. Taken together, our findings indicate that deacetylation of p53 by histone deacetylases is likely to be part of the mechanisms that control the physiological activity of p53.

The histone deacetylase-3 complex contains nuclear receptor corepressors

Acetylation and deacetylation of nucleosomal histones have profound effects on gene transcription in all eukaryotes. In humans, three highly homologous class I and four class II histone deacetylase (HDAC) enzymes have been identified to date. The class I deacetylases HDAC1 and HDAC2 are components of multisubunit complexes, one of which could associate with the nuclear hormone receptor corepressor, N-CoR. N-CoR also interacts with class II deacetylases HDAC4, HDAC5, and HDAC7. In comparison with HDAC1 and HDAC2, HDAC3 remains relatively uncharacterized, and very few proteins have been shown to interact with HDAC3. Using an affinity purification approach, we isolated an enzymatically active HDAC3 complex that contained members of the nuclear receptor corepressor family. Deletion analysis of N-CoR revealed that HDAC3 binds multiple N-CoR regions in vitro and that all of these regions are required for maximal binding in vivo. The N-CoR domains that interact with HDAC3 are distinct from those that bind other HDACs. Transient overexpression of HDAC3 and microinjection of Abs against HDAC3 showed that a component of transcriptional repression mediated by N-CoR depends on HDAC3. Interestingly, data suggest that interaction with a region of N-CoR augments the deacetylase activity of HDAC3. These results provide a possible molecular mechanism for HDAC3 regulation and argue that N-CoR is a platform in which distinct domains can interact with most of the known HDACs.

Experience of corporate medical assistance clinics during the Centennial Olympic Games, Atlanta, 1996

The health of travelers returning home from developing countries has received increased attention in recent years. Much of this attention has centered on immunizations, malaria chemoprophylaxis and treatment of traveler's diarrhea. In contrast, there are very few data on the health problems of international travelers to developed countries such as the United States. We studied the experience of two corporate medical assistance clinics established for both national and international travelers to Atlanta, Georgia during the Centennial Summer Olympic Games in 1996.

Ligand-induced recruitment of a histone deacetylase in the negative-feedback regulation of the thyrotropin beta gene

We have investigated ligand-dependent negative regulation of the thyroid-stimulating hormone beta (TSHbeta) gene. Thyroid hormone (T3) markedly repressed activity of the TSHbeta promoter that had been stably integrated into GH(3 )pituitary cells, through the conserved negative regulatory element (NRE) in the promoter. By DNA affinity binding assay, we show that the NRE constitutively binds to the histone deacetylase 1 (HDAC1) present in GH(3 )cells. Significantly, upon addition of T3, the NRE further recruited the thyroid hormone receptor (TRbeta) and another deacetylase, HDAC2. This recruitment coincided with an alteration of in vivo chromatin structure, as revealed by changes in restriction site accessibility. Supporting the direct interaction between TR and HDAC, in vitro assays showed that TR, through its DNA binding domain, strongly bound to HDAC2. Consistent with the role for HDACs in negative regulation, an inhibitor of the enzymes, trichostatin A, attenuated T3-dependent promoter repression. We suggest that ligand-dependent histone deacetylase recruitment is a mechanism of the negative-feedback regulation, a critical function of the pituitary-thyroid axis.

RBP1 recruits both histone deacetylase-dependent and -independent repression activities to retinoblastoma family proteins

Retinoblastoma (RB) tumor suppressor family proteins block cell proliferation in part by repressing certain E2F-specific promoters. Both histone deacetylase (HDAC)-dependent and -independent repression activities are associated with the RB "pocket." The mechanism by which these two repression functions occupy the pocket is unknown. A known RB-binding protein, RBP1, was previously found by our group to be an active corepressor which, if overexpressed, represses E2F-mediated transcription via its association with the pocket. We show here that RBP1 contains two repression domains, one of which binds all three known HDACs and represses them in an HDAC-dependent manner while the other domain functions independently of the HDACs. Thus, RB family members repress transcription by recruiting RBP1 to the pocket. RBP1, in turn, serves as a bridging molecule to recruit HDACs and, in addition, provides a second HDAC-independent repression function.

Cloning and characterization of the mouse histone deacetylase-2 gene

Histone deacetylase-2 (HDAC2) is a component of a complex that mediates transcriptional repression in mammalian cells. A mouse HDAC2 cDNA was used to identify several recombinant clones containing the entire mouse HDAC2 gene. The mouse HDAC2 gene spans over 36 kilobase pairs and is composed of 14 exons (ranging from 58 to 362 nucleotides in length) and 13 introns (ranging from 75 base pairs to 19 kilobase pairs in length). Primer extension analysis with total RNA from NIH3T3 cells revealed a major transcriptional start site at 221 base pairs 5' of the ATG translational start codon. Upstream of the transcriptional start site, no canonical TATA box was found, but binding sites for several known transcription factors were identified. Transient transfection studies with 5' deletion mutants localized the promoter to no more than 76 base pairs upstream from the major transcriptional start site. Fluorescence in situ hybridization mapped mouse HDAC2 to chromosomal location 10B1, which is in close proximity to the growth factor-inducible gene fisp-12. Information concerning the genomic organization and promoter of HDAC2 will be useful in studies of the regulation of histone deacetylase activities, which in turn are important in studies of the regulation of transcriptional repression in mammalian cells.

Isolation and characterization of cDNAs corresponding to an additional member of the human histone deacetylase gene family

Several human cDNAs encoding a histone deacetylase protein, HDAC3, have been isolated. Analysis of the predicted amino acid sequence of HDAC3 revealed an open reading frame of 428 amino acids with a predicted molecular mass of 49 kDa. The HDAC3 protein is 50% identical in DNA sequence and 53% identical in protein sequence compared with the previously cloned human HDAC1. Comparison of the HDAC3 sequence with human HDAC2 also yielded similar results, with 51% identity in DNA sequence and 52% identity in protein sequence. The expressed HDAC3 protein is functionally active because it possesses histone deacetylase activity, represses transcription when tethered to a promoter, and binds transcription factor YY1. Similar to HDAC1 and HDAC2, HDAC3 is ubiquitously expressed in many different cell types.

The hepatitis B virus X-associated protein, XAP3, is a protein kinase C-binding protein

The hepatitis B virus X protein induces transcriptional activation of a wide variety of viral and cellular genes. In addition to its ability to interact directly with many nuclear transcription factors, several reports indicate that the X protein stimulates different cytoplasmic kinase signal cascades. Using the yeast two-hybrid screen, we have isolated a clone designated X-associated protein 3 (XAP3) that encodes a human homolog of the rat protein kinase C-binding protein. One of the activation domains of X (amino acids 90-122) is required for binding to XAP3, while the NH2-terminal part of XAP3 is necessary for binding to X. Both X and XAP3 bound specifically to the eta PKC isoenzyme synthesized in rabbit reticulocyte lysates. Overexpression of XAP3 enhanced X transactivation activity. These results support earlier findings that one of the mechanisms of transactivation by X is through involvement with the cellular protein kinase C pathway.

Differential effects of nuclear receptor corepressor (N-CoR) expression levels on retinoic acid receptor-mediated repression support the existence of dynamically regulated corepressor complexes

Thyroid hormone and retinoic acid receptors are members of the nuclear receptor superfamily of ligand-dependent transcription factors that stimulate the transcription of target genes in the presence of activating ligands and repress transcription in their absence. Transcriptional repression by the thyroid hormone and retinoic acid receptors has been proposed to be mediated by the nuclear receptor corepressor, N-CoR, or the related factor, SMRT (silencing mediator of retinoic acid and thyroid hormone receptors). Recent studies have suggested that transcriptional repression by N-CoR involves a corepressor complex that also contains mSin3A/B and the histone deacetylase, RPD3. In this manuscript, we demonstrate that transcriptional repression by the retinoic acid receptor can be either positively or negatively regulated by changes in the levels of N-CoR expression, suggesting a relatively strict stoichiometric relationship between N-CoR and other components of the corepressor complex. Consistent with this interpretation, overexpression of several functionally defined domains of N-CoR also relieve repression by nuclear receptors. N-CoR is distributed throughout the nucleus in a nonuniform pattern, and a subpopulation becomes concentrated into several discrete dot structures when highly expressed. RPD3 is also widely distributed throughout the nucleus in a nonuniform pattern. Simultaneous imaging of RPD3 and N-CoR suggest that a subset of each of these proteins colocalize, consistent with the existence of coactivator complexes containing both proteins. In addition, a substantial fraction of both N-CoR and mSin3 A/B appear to be independently distributed. These observations suggest that interactions between RPD3 and Sin3/N-CoR complexes may be dynamically regulated.

Histone deacetylases associated with the mSin3 corepressor mediate mad transcriptional repression

Transcriptional repression by Mad-Max heterodimers requires interaction of Mad with the corepressors mSin3A/B. Sin3p, the S. cerevisiae homolog of mSin3, functions in the same pathway as Rpd3p, a protein related to two recently identified mammalian histone deacetylases, HDAC1 and HDAC2. Here, we demonstrate that mSin3A and HDAC1/2 are associated in vivo. HDAC2 binding requires a conserved region of mSin3A capable of mediating transcriptional repression. In addition, Mad1 forms a complex with mSin3 and HDAC2 that contains histone deacetylase activity. Trichostatin A, an inhibitor of histone deacetylases, abolishes Mad repression. We propose that Mad-Max functions by recruiting the mSin3-HDAC corepressor complex that deacetylates nucleosomal histones, producing alterations in chromatin structure that block transcription.