Unlocking the Role Of Orphan Solute Carrier SLC38A10 In Brain Metabolism : The SLC38A10 transporter in nutrient and metabolic regulation

Sammanfattning: Membrane transporters are the primary gatekeepers of cells and regulate the transport of nutrients, metabolites, ions, water, and neurotransmitters into and across the human cells. The solute carrier transporters (SLCs) are the most prominent transporters, comprising 430 members divided into 65 subfamilies. SLCs are located on the plasma membrane and organelles such as mitochondria, vesicles, peroxisomes, endoplasmic reticulum, Golgi, and lysosomes. This thesis aimed to study SLCs of the SLC38 family under nutrient stress, focused particularly on the orphan SLC38A10 transporter.In Paper I, regulation of members of SLC38 family transporter, after amino acid starvation in mouse hypothalamic cells and primary cortex cells, was studied using microarrays and qPCR. We found several members of the SLC38 family that were strongly affected under amino acid starvation and showing a potential role in amino acid signaling in the brain. In Paper II, we performed a cellular and tissue localization and functional study of SLC38A10 transporter and revealed that SLC38A10 was expressed in both excitatory and inhibitory neurons in the mouse brain and has a unique subcellular localization in the ER and Golgi membrane. Furthermore, knockdown of the SLC38A10 gene resulted in reduced nascent protein synthesis in PC12 cells. Further, to unlock the biological function of the SLC38A10 transporter, in Paper III and Paper IV, we used SLC38A10 knockout mouse model.In Paper III, the goal was to uncover the role of SLC38A10 in acute glutamate and oxidative stress. Here, we found that a loss of SLC38A10 KO resulted in changes in the p53 levels and affected the mitochondrial function. Thus, this study established a possible role of SLC38A10 in cell survival, linked with p53, in mouse primary cortex cells. In Paper IV, we examined the role of SLC38A10 in amino acid metabolism and nutrient sensing in the mTOR signaling pathway. We performed complete amino acid starvation and refeed experiment on SLC38A10 knockout primary cortex cells. We concluded that SLC38A10 acts as a transceptor and regulates mTOR-dependent protein and lipid synthesis in brain cells, corroborating the findings from Paper II. To summarize, the present work has uncovered the function of SLC38A10 in the brain. It also provides knowledge of SLC38A10’s role in amino acid metabolism and signaling pathway(s). The findings of this thesis will enhance an understanding of SLC38A10 transporter and provide insight into future disease targeted drug studies focused on metabolic disorder and neurodegenerative disease.