Structural insights into the substrate uptake and inhibition of the human creatine transporter (hCRT)
Abstract
Creatine plays a vital role in cellular energy production and adenosine triphosphate (ATP) homeostasis and has also been identified as a neurotransmitter in the mammalian brain. Creatine is transported into cells by the human creatine transporter (hCRT) (SLC6A8), an Na + /Cl − -dependent symporter encoded on the X chromosome. Mutations in hCRT cause cerebral creatine deficiency syndrome 1, a neurological disorder marked by intellectual disability, speech delay, and seizures. Beyond its role in the brain and muscle, hCRT is highly expressed in metabolically active tumors. Many cancer cells, including colorectal cancer and glioblastoma, upregulate hCRT to sustain intracellular creatine levels and buffer ATP under energy stress. Pharmacological blockade of hCRT by RGX202 has been shown to impair tumor growth by disrupting energy homeostasis. Here, we report the high-resolution cryo-Electron Microscopy (cryo-EM) structures of human hCRT in three states: apo, creatine-bound, and RGX202-bound. hCRT adopts a canonical LeuT-fold with 12 transmembrane helices and two pseudosymmetric inverted repeats. Creatine is coordinated in the central substrate-binding site through interactions with transmembrane helices TM1, TM3, TM6, and TM8, while the inhibitor RGX202 occupies the same binding pocket, engaging in overlapping contacts that competitively block creatine access. Our structural and mechanistic findings clarify substrate recognition and inhibitory binding of hCRT, providing a molecular rationale for targeting hCRT in both inherited metabolic diseases and cancer therapy.
Article Details
Journal Info
Proceedings of the National Academy of Sciences
National Academy of Sciences
Authors (18)
Xinyi Yuan
Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Hangzhou Normal University
Jian Yin
Ministry of Education Key Laboratory of Protein Science, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University
Chang Liu
Xudong Chen
Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University
Meiying Chen
Ministry of Education Key Laboratory of Protein Science, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University
Yixue Wang
Ministry of Education Key Laboratory of Protein Science, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University
Zi Yang
Beijing National Laboratory for Molecular Science, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering
Yue Wang
Li Jiang
Department of Radiation Oncology The First Affiliated Hospital of Guangxi Medical University Nanning China
Niyun Zhou
Ministry of Education Key Laboratory of Protein Science, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University
Xiaojuan Wang
Department of Endocrinology, Genetics and Metabolism, National Center for Children’s Health, Beijing Children’s Hospital Capital Medical University
Botong Liu
Ministry of Education Key Laboratory of Protein Science, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University
Zhaoqi Ma
College of Biological Science, China Agricultural University
Kaiyan Wang
National Clinical Research Center for Oral Diseases & Shaanxi Key Laboratory of Stomatology, School of Stomatology, The Fourth Military Medical University
Hongen Li
Department of Ophthalmology, The Chinese People’s Liberation Army General Hospital & The Chinese People’s Liberation Army Medical School
Sensen Zhang
Yongfeng Shang
Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Hangzhou Normal University
Maojun Yang
Ministry of Education Key Laboratory of Protein Science, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University