Table_1_Transcriptomic Analysis Reveals a Sex-Dimorphic Influence of GAT-2 on Murine Liver Function.XLSX

Accumulating evidence shows that the γ-amino butyric acid (GABA)ergic system affects the functions of different organs, and liver is one of the most sex-dimorphic organs in animals. However, whether and how the GABAergic system influences liver function in a sex-specific manner at the intrinsic molecular level remains elusive. In this study, firstly, we find that the levels of GABA are significantly increased in the livers of female mice with GABA transporter (GAT)-2 deficiency (KO) whereas it only slightly increased in male GAT-2 KO mice. Apart from the amino acid profiles, the expressions of toll-like receptors (TLRs) also differ in the livers of female and male KO mice. Moreover, RNA-seq results show 2,227 differentially expressed genes (DEGs) in which 1,030 are upregulated whereas 1,197 that are downregulated in the livers of female KO mice. Notably, oxidative phosphorylation, non-alcoholic fatty liver disease, Huntington's disease, and peroxisome proliferator-activated receptor (PPAR) signaling pathways are highly enriched by GAT-2 deficiency, indicating that these pathways probably meditate the effects of GAT-2 on female liver functions, on the other hand, only 1,233 DEGs, including 474 are upregulated and 759 are downregulated in the livers of male KO mice. Interestingly, retinol metabolism, PPAR signaling pathway, and tuberculosis pathways are substantially enriched by GAT-2 deficiency, suggesting that these pathways may be responsible for the effects of GAT-2 on male liver functions. Collectively, our results reveal the sex-dimorphic effects of GAT-2 in guiding liver functions, and we propose that targeting the GABAergic system (e.g., GATs) in a sex-specific manner could provide previously unidentified therapeutic opportunities for liver diseases.越来越多的研究证据表明，γ-氨基丁酸能系统（γ-amino butyric acid (GABA)ergic system）可调控多种器官的生理功能，而肝脏是动物体内性别二态性最为显著的器官之一。目前，γ-氨基丁酸能系统是否以及如何在内在分子层面以性别特异性方式影响肝脏功能，仍尚未明确。 本研究首先发现：在γ-氨基丁酸转运体2（GABA transporter, GAT-2）敲除（knockout, KO）雌性小鼠的肝脏组织中，γ-氨基丁酸的水平显著升高；而在同基因型雄性敲除小鼠的肝脏中，γ-氨基丁酸水平仅出现小幅上升。除氨基酸谱存在性别特异性差异外，Toll样受体（toll-like receptors, TLRs）的表达在雌雄敲除小鼠的肝脏中也存在显著差异。 此外，RNA测序（RNA-seq）结果显示，雌性敲除小鼠的肝脏中共鉴定出2227个差异表达基因（differentially expressed genes, DEGs），其中1030个基因上调、1197个基因下调。值得注意的是，GAT-2敲除显著富集了氧化磷酸化、非酒精性脂肪肝病、亨廷顿病以及过氧化物酶体增殖物激活受体（peroxisome proliferator-activated receptor, PPAR）信号通路，提示上述通路可能介导GAT-2对雌性肝脏功能的调控作用；与之相对，雄性敲除小鼠的肝脏中共鉴定出1233个差异表达基因，其中474个基因上调、759个基因下调。有趣的是，GAT-2敲除仅显著富集了视黄醇代谢、PPAR信号通路以及结核病通路，表明此类通路可能参与GAT-2对雄性肝脏功能的调控。 综上，本研究揭示了GAT-2在调控肝脏功能过程中存在的性别二态性效应，并提出以性别特异性方式靶向γ-氨基丁酸能系统（例如GATs），可为肝脏疾病提供此前未被发掘的治疗新机遇。