ADAR2 and Adipose Dysfunction in Aging

 描述(申请人提供)：衰老是一个复杂的过程，涉及不断积累的细胞损伤。预防这些损害的干预措施将改善与衰老相关的病理。随着年龄的增长，脂肪功能障碍增加，从而显著改变脂肪质量、再分配和功能，导致代谢失衡，增加心脏代谢性疾病的风险。脂肪细胞的持续周转，从而重新招募新的前脂肪细胞(或脂肪干细胞)和脂肪细胞是维持脂肪质量和功能所必需的。我们最近的研究表明，脂肪储备中的年龄相关性功能障碍归因于前脂肪细胞无法随着年龄的增长而分化为脂肪细胞，这是由于成脂微RNA(MiRNAs)的去调节。前脂肪细胞的分化受遗传和表观遗传机制的调节。了解这一现象很重要，因为它将有助于(I)更好地了解衰老表型和脂肪功能障碍之间的关系，以及(Ii)确定治疗或预防与衰老相关的心脏代谢性疾病的靶点。作用于RNAs的腺苷脱氨酶(ADAR)家族在转录后调节中起关键作用，并通过RNA编辑对RNA和蛋白质的多样性至关重要。ADAR的缺失导致美国百岁老人死亡率上升，增加了与年龄相关的神经疾病(如痴呆症和某些癌症)的风险。ADAR的缺失还会导致肥胖和胰岛素抵抗的增加。ADARS目前被认为是治疗某些神经系统疾病和癌症的良好靶点。我们假设，随着年龄的增长，ADAR的减少在观察到的年龄介导的脂肪功能障碍中发挥了作用。我们将通过提出三个目标来检验这一假设。我们的研究将使用从年轻的Fischer 344×Brown挪威杂交大鼠(6mo)的内脏脂肪中分离出的前脂肪细胞与老年FBN大鼠(14mo、24mo、30mo)进行比较。这些大鼠与人类相似，随着年龄的增长，它们会出现肥胖和胰岛素抵抗。目的1：探讨ADARs在miRNA调节衰老脂肪功能中的作用。其目的是研究ADAR的表达和活性是否随着年龄的增长而改变，并在成脂miRNA和脂肪功能的损害中发挥作用。目的2：研究ADAR对成脂miRNA靶点的调节作用：目的是确定ADAR是否调节成脂miRNA(miR-143)、成脂/成骨miRNA(miR-204)和成骨miRNA(miR-22)的mRNA靶点。目的3：证明调节衰老前脂肪细胞中ADAR水平将改善脂肪细胞的功能。其目的是通过使用获得或丧失功能的方法来调节ADAR水平，以证明ADAR介导的RNA编辑通路在随年龄增长的脂肪细胞前功能障碍中所起的作用。我们提出的研究是新颖和创新的，将首次探索RNA编辑在脂肪生物学中的作用及其与代谢功能障碍的关系，并确定新的治疗靶点。这些研究将为马歇尔大学本科生在生物医学领域提供极好的研究经验和机会。

 DESCRIPTION (provided by applicant): Aging is a complex process that involves continuous accumulation of cellular damage. Interventions to prevent these damages will improve aging related pathologies. Adipose dysfunction increases with age, which dramatically alters fat mass, redistribution and function, leading to metabolic imbalance and increased risk to cardiometabolic diseases. Continuous turnover of adipose cells and thus recruitment of new pre-adipocytes (or adipose derived stem cells) and adipocytes is essential in maintaining adipose mass and function. Our recent studies showed age-dependent dysfunction in fat depots attributed to inability of pre-adipocytes to differentiate into adipocytes with aging due to de-regulation of adipogenic microRNAs (miRNAs). Pre-adipocyte differentiation is regulated by both genetic and epigenetic mechanisms. Understanding this phenomenon is important, since it will help (i) to better understand the relationship between the aging phenotype and adipose dysfunction and (ii) identify targets to treat or prevent cardiometabolic diseases that are associated with aging. Adenosine Deaminase acting on RNAs (ADAR) family of enzymes are key in post-transcriptional regulation and essential for RNA and protein diversity through RNA editing. Loss of ADARs resulted in increased mortality in US centenarians, increased risk to age-associated neurological diseases such as dementia and certain cancers. Loss of ADAR also resulted in increased obesity and insulin resistance. ADARs are currently explored as a good therapeutic target for certain neurological diseases and cancer. We hypothesize a loss of ADARs with aging plays a role in the observed age-mediated adipose dysfunction. We will test this hypothesis by proposing three aims. Our studies will use pre-adipocytes isolated from the visceral fat of young Fischer 344 x Brown Norway hybrid rats (6mo) compared to aged FBN rats (14mo, 24mo, 30mo). These rats are similar to humans and develop adiposity and insulin resistance with increasing age. AIM 1: To demonstrate the role for ADARs in the miRNA regulation of adipose function in aging. The goal of this aim is to investigate if ADAR expression and activity are altered with aging and it plays a role in the impairment of adipogenic miRNA and adipose function. AIM 2: To demonstrate that ADAR regulates adipogenic miRNA targets with aging: The goal of this aim is to determine if ADARs regulate the mRNA targets of adipogenic miRNA (miR-143), adipogenic/osteogenic miRNA (miR-204) and osteogenic miRNA (miR-22). AIM 3: To demonstrate that modulation of ADAR levels in aging pre-adipocytes will improve adipocyte function. The goal of this aim is to demonstrate the role of ADAR-mediated RNA editing pathways in pre-adipocyte dysfunction with aging by using gain or loss of function approaches for modulating ADAR levels. Our proposed studies are novel and innovative and will, for the first time, explore the role of RNA editing in adipose biology and its relation to metabolic dysfunction and identify novel therapeutic targets. These studies will provide excellent research experience and opportunity for Marshall University undergraduates in the biomedical field.