Opioid Peptide Synthesizing Enzymes

分别由基因PCSK 1和PCSK 2编码的激素原转化酶PC 1/3和PC 2是 负责从较大前体释放阿片样活性肽的内切蛋白水解酶 proteins.激素原转换酶不仅在阿片肽介导的疼痛信号中起重要作用， 而且还在许多其他神经回路中起作用，包括在奖励通路和下丘脑中， 参与进食和能量平衡的回路。例如，罕见和常见的变异， PCSK 1是人类肥胖的主要危险因素，可能是由于下丘脑 肽能加工在与临床医生的合作中， 在PCSK 1中，我们最近已经确定突变的人和小鼠PC 1/3蛋白受到 靶向可能导致下丘脑蛋白抑制应激的缺陷。根据我们之前的发现 小鼠PC 1/3蛋白在合成过程中发生寡聚化，我们提出显性负相互作用 在人类PC 1/3杂合子肥胖表型中起主要作用，影响前体加工， 参与饱腹感信号传导的生物活性肽。我们认为，外部压力甚至会加剧 轻度形式的PC 1/3构象困扰，损害PC 1/3的C-末端裂解为更小，更小， 活性形式。这些过程最终将集中到严重损害前体处理，例如。 阿黑皮素原裂解为β-内啡肽、ACTH，最重要的是，裂解为α-内啡肽。 MSH。在本提案中，我们将使用CRISPR工程化的细胞模型来阐明细胞生物学， 三种人类PC 1/3变异体和突变体的前体加工功效已知与 肥胖风险增加。其次，我们将建立两种常见人类PCSK 1的小鼠模型， 肥胖突变体，以及第三种罕见但高度受损的突变体模型，以扩展细胞中的发现。 培养到实际的分泌组织，并确定具体的生理变化，这是基础， PCSK 1介导的肥胖表型。最后，我们将测试我们的假设，即加工缺陷， 阿黑皮素原合成神经元通过选择性消除Pcsk 1成为肥胖表型的基础 使用floxed Pcsk 1无效小鼠模型在表达阿黑皮素原的细胞中表达。的结果 这些研究将阐明控制下丘脑肽产生的生物合成机制 这导致人类对各种疾病易感性，从肥胖到药物中的奖赏途径， 成瘾

The prohormone convertases PC1/3 and PC2, encoded by the genes PCSK1 and PCSK2 respectively, are the endoproteolytic enzymes responsible for the liberation of opioid-active peptides from larger precursor proteins. Prohormone convertases play important roles not only in opioid peptide-mediated pain signaling but also function in many other neuronal circuits, including in reward pathways and in hypothalamic circuits involved in feeding and energy homeostasis. For example, both rare and common variations in PCSK1 function as major risk factors for human obesity, potentially due to deficiencies in hypothalamic peptidergic processing. In collaboration with clinicians who have identified children with novel mutations in PCSK1, we have recently determined that mutant human and mouse PC1/3 proteins are subject to targeting defects which are likely to result in hypothalamic proteostatic stress. Based on our prior finding that mouse PC1/3 proteins oligomerize during synthesis, we propose that dominant-negative interactions play a major role in human PC1/3 heterozygote obesity phenotypes, affecting precursor processing to bioactive peptides involved in satiety signaling. We propose that external stressors will exacerbate even mild forms of PC1/3 conformational distress, impairing C-terminal cleavage of PC1/3 to the smaller, more active forms. These processes will ultimately converge to strongly impair precursor processing, eg. proopiomelanocortin cleavage to beta-endorphin, ACTH, and most importantly, to the anorexic peptide α- MSH. In the present proposal we will use CRISPR-engineered cell models to elucidate the cell biology and precursor processing efficacy of three human PC1/3 variants and mutants known to be strongly associated with increased risk of obesity. Secondly, we will create mouse models of two common human PCSK1 obesity mutants, and a third model of a rare but highly impaired mutant, to extend findings made in cell culture to actual secretory tissues, and to identify the specific physiologic alterations which underlie the PCSK1-mediated obesity phenotype. Lastly, we will test our hypothesis that processing deficits in proopiomelanocortin-synthesizing neurons underlie the obesity phenotype by selectively eliminating Pcsk1 expression in proopiomelanocortin-expressing cells using a floxed Pcsk1 null mouse model. The results of these studies will illuminate the biosynthetic mechanisms controlling hypothalamic peptide production that contribute to human susceptibility to a variety of diseases, from obesity to reward pathways in drug addiction.