Yang Zhao, Stemmer Paul M, Petriello Michael C
Institute of Environmental Health Sciences, Wayne State University, Detroit, MI 48202, USA.
Department of Pharmaceutical Sciences, College of Pharmacy, Wayne State University, Detroit, MI 48202, USA.
Toxics. 2022 Jan 28;10(2):60. doi: 10.3390/toxics10020060.
The hepatic xenobiotic metabolizing enzyme flavin-containing monooxygenase 3 (FMO3) has been implicated in the development of cardiometabolic disease primarily due to its enzymatic product trimethylamine-N oxide (TMAO), which has recently been shown to be associated with multiple chronic diseases, including kidney and coronary artery diseases. Although TMAO may have causative roles as a pro-inflammatory mediator, the possibility for roles in metabolic disease for FMO3, irrespective of TMAO formation, does exist. We hypothesized that FMO3 may interact with other proteins known to be involved in cardiometabolic diseases and that modulating the expression of FMO3 may impact on these interaction partners. Here, we combine a co-immunoprecipitation strategy coupled to unbiased proteomic workflow to report a novel protein:protein interaction network for FMO3. We identified 51 FMO3 protein interaction partners, and through gene ontology analysis, have identified urea cycle as an enriched pathway. Using mice deficient in FMO3 on two separate backgrounds, we validated and further investigated expressional and functional associations between FMO3 and the identified urea cycle genes. FMO3-deficient mice showed hepatic overexpression of carbamoylphosphate synthetase (CPS1), the rate-limiting gene of urea cycle, and increased hepatic urea levels, especially in mice of FVB (Friend leukemia virus B strain) background. Finally, overexpression of FMO3 in murine AML12 hepatocytes led to downregulation of CPS1. Although there is past literature linking TMAO to urea cycle, this is the first published work showing that FMO3 and CPS1 may directly interact, implicating a role for FMO3 in chronic kidney disease irrespective of TMAO formation.
肝脏外源性物质代谢酶含黄素单加氧酶3（FMO3）被认为与心脏代谢疾病的发生有关，主要是因为其酶促产物三甲胺 - N - 氧化物（TMAO），最近研究表明TMAO与多种慢性疾病相关，包括肾脏疾病和冠状动脉疾病。尽管TMAO可能作为促炎介质发挥致病作用，但FMO3在代谢疾病中的作用可能性确实存在，无论TMAO是否形成。我们假设FMO3可能与已知参与心脏代谢疾病的其他蛋白质相互作用，并且调节FMO3的表达可能会影响这些相互作用伙伴。在这里，我们结合了共免疫沉淀策略与无偏向蛋白质组学工作流程，报告了一种新的FMO3蛋白质 - 蛋白质相互作用网络。我们鉴定了51个FMO3蛋白质相互作用伙伴，并通过基因本体分析，确定尿素循环是一条富集途径。我们使用在两种不同背景下缺乏FMO3的小鼠，验证并进一步研究了FMO3与已鉴定的尿素循环基因之间的表达和功能关联。FMO3缺陷小鼠肝脏中尿素循环的限速基因氨甲酰磷酸合成酶（CPS1）过表达，肝脏尿素水平升高，特别是在FVB（弗氏白血病病毒B株）背景的小鼠中。最后，在小鼠AML12肝细胞中过表达FMO3导致CPS1下调。尽管过去有文献将TMAO与尿素循环联系起来，但这是首次发表的研究表明FMO3和CPS1可能直接相互作用，这意味着无论TMAO是否形成，FMO3在慢性肾病中都发挥作用。
