| The prevalence of overweight and obesity has increased globally during the past few decades,and increased fat mass promotes morbidity and mortality.Recent evidence have proved that adipose distribution is actually the major reason.Accumulation of visceral adipose tissue is an important risk factor for metabolic disorders and cardiovascular disease.Since white adipose tissue is the main adipose of individual.To convert visceral adipose by promoting beiging of white adipose tissue may provide a therapeutic target to curb obesity.There are various kind of progenitor cells in white fat,whose distribution are deport specific.PDGFRα positive progenitor cells which can be differentiated into both brown adipocyte and white adipocyte in vitro,are considered to be bi-potential adipocyte progenitors.CD137 positive progenitor cells which can only be differentiated into brown adipocyte,are considered to be beige adipocyte progenitors.Glucocorticoid are vital in regulating adipose redistribution and visceral adipose accumulation and it can mediating the function of white adipose expansion and function and the brown adipose function.Our previous study proved the glucocorticoid’s suppression of white adipose beiging.In order to discover the regulation of visceral obesity by glucocorticoid and the molecular mechanisms inside it.By utilizing PDGFRα and CD137 positive progenitor cells,we have investigated the cell specific effect of glucocorticoid on transcriptionally regulating mi R-27 b expression thus mediating the beiging function of deport-specific progenitor adipocytes.By precise exploring the biology of adipocyte progenitor cellswe can define the nature of the adipocyte progenitor cells within the crude stroma cell fraction and figure out whether and how glucocorticoid’s regional specific effect cause systemic dysfunction and disease and developing mechanism-based interventions accordingly.Our research was divided into three parts.Part I: The relationship between visceral adipose beiging level and visceral adipose function.Part II: The cell-specific regulation of glucocorticoid in visceral adipocyte progenitor’s beiging potential.Part III: The molecular mechanism of glucocorticoid’s cell-specific regulation in deport-specific progenitor adipocytes’ beiging function.The relationship between visceral adipose beiging level and visceral adipose function.Objective.The prevalence of overweight and obesity has increased globally during the past few decades,and increased fat mass promotes morbidity and mortality.Recent evidence have proved that adipose distribution is actually the major reason.Accumulation of visceral adipose tissue is an important risk factor for metabolic disorders and cardiovascular disease.Since white adipose tissue is the main adipose of individual.To convert visceral adipose by promoting beiging of white adipose tissue may provide a therapeutic target to curb obesity.Thus,in this part,we are aiming at discover the relationship between beiging function of visceral adipose and visceral obesity.Methods.Visceral adipose samples of normal and obese people.We use Real-time PCR,Western blot and immumohistochemical staining to observe the adipocyte function and beiging level of individual samples.Correlation analysis of UCP1 expression and BMI or WHR.Result.The UCP1 expression level of visceral adipose of obese individuals were lower than normal individuals.With the increase of visceral obesity,visceral fat beige degree decrease,and visceral adipose improve insulin sensitivity factor expression of adiponectin reduced,increased proinflammatory factor synthesis,anti-inflammatory factor synthesis.Conclusion.The low level of visceral fat is probably the most important cause of visceral obesity and insulin resistance.The cell-specific regulation of glucocorticoid in visceral adipocyte progenitor’s beiging potential.Objective.Glucocorticoid are vital in regulating adipose redistribution and visceral adipose accumulation and it can mediating the function of white adipose expansion and function and the brown adipose function.Our previous study proved the glucocorticoid’s suppression of white adipose beiging.There are various kind of progenitor cells in white adipose,whose distribution are deport specific.In the first part,we observed that the decreasing beiging function may be the vital cause of visceral obesity and insulin resistance.In this part,we will discovered the cell specific effect of glucocorticoid on adipocytes beiging by utilizing the progenitor cells isolated from subcutaneous or visceral adipose tissue.Method.By flow cytometer analysis,we observed the percentage of PDGFRa positive progenitors and CD137 positive progenitors in subcutaneous or visceral adipose tissue.Then we use magnetic cell sorting to isolate PDGFRa positive progenitors and CD137 positive progenitors and to discover the differentiation potential of these progenitors.By Real-time PCR and immunofluorescent staining,we can observe glucocorticoid’s regulation of PDGFRa positive progenitors and CD137 positive progenitors’ beiging potentials.Result.Flow cytometer analyzed the subcutaneous and visceral adipocytes of mice at different ages.The result showed that PDGFRa positive progenitors took the major proportion in visceral adipocytes while CD137 positive progenitors were the majority in subcutaneous adipocytes.Glucocorticoid remarkably suppressed the beiging function of PDGFRa positive cells but barely influenced CD137 positive cells’ function.Conclusion.Glucocorticoid extensively regulate PDGFRa positive progenitors which were contained more in visceral adipose.However,it hardly has any effect on CD137 positive cells which has a higher proportion in subcutaneous adipose.The molecular mechanism of glucocorticoid’s cell-specific regulation in deport-specific progenitor adipocytes’ beiging function.Objective.Our previous study proved that glucocorticoid transcriptionally up-regulate mi R-27 b and pointed to a critical role for mi R-27 b in the control of the beiging effect on white adipose through PRDM16.Although we have indicated the suppressing function of glucocorticoid on white adipose beiging.Clinical study have found that low doses of glucocorticoids for long periods of time lead to central obesity,namely visceral fat accumulation.In the previous part,we have observed that glucocorticoid extensively regulate PDGFRa positive progenitors which were contained more in visceral adipose while barely effect CD137 positive cells which has a higher proportion in subcutaneous adipose,indicating the cell-specific mediation of glucocorticoid in suppressing beiging function and causing visceral obesity.In this part,we will further investigate the molecular mechanism underlying.Method.By real-time PCR,we measured the mi R-27 b expression level in weight normal and obese individuals.To verify mi R-27b’s mediation of adipose beiging,we performed gain-and-off experiments in human visceral adipocytes isolated from weight normal and obese individuals.Using adipocyte progenitors sorting from subcutaneous or visceral adipose,we observed mi R-27 b expression level and the beiging level of adipocytes with or without DEX stimulation.To further testify mi R-27b’s role in promoting beiging level in visceral adipocyte and improving individuals’ metabolism,we established diet induced obese(DIO)mice model with anti-mi R-27 b injection to evaluate the overall metabolic and adipose function changes of mice.Results.With the increasing level of BMI,mi R-27 b expression in visceral adipose tissue was rasing,and was negatively correlated with UCP1 expression.Overexpressed mi R-27 b strongly suppressed visceral adipocytes’ beiging level and lower cellular oxygen consumption of weight normal individuals.Obese individuals’ visceral adipocytes transfected with anti-mi R-27 b showed elevated beiging level and cellular oxygen consumption.Sorted PDGFRa positive progenitors expressed higher level of mi R-27 b than CD137 positive progenitors.After DEX stimulation,mi R-27 b expression were increased in PDGFRa positive cells while were barely altered in CD137 positive cells.DIO mice with anti-mi R-27 b injection showed increased beiging function of visceral adipose,converted visceral obesity and improved insulin sensitivity.Conclusion.In vitro and in vivo study point out the role of mi R-27 b in mediating visceral obesity by suppressing adipocytes’ beiging function.Our study demonstrated the cell-specific regulation of glucocorticoid on mi R-27 b expression further mediated the beiging and cellular function of deport specific adipocytes progenitors.By precise exploring the biology of adipocyte progenitor cells we can define the nature of the adipocyte progenitor cells within the crude stroma cell fraction and figure out whether and how glucocorticoid’s regional specific effect cause systemic dysfunction and disease and developing mechanism-based interventions accordingly. |
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