Morris Nechama - Arginine depletion attenuates renal cystogenesis in tuberous sclerosis complex model
Arginine depletion attenuates renal cystogenesis in tuberous sclerosis complex model
https://www.sciencedirect.com/science/article/pii/S2666379123001921
Cell Reports Medicine. June 20, 2023
Athar Amleh1,2, Hadass Pri Chen2,3, Lana Watad1,2, Ifat Abramovich4, Bella Agranovich4, Eyal Gottlieb4, Iddo Z. Ben-Dov3,5, Morris Nechama1,2,6* and Oded Volovelsky1,2,6,7*
- Pediatric Nephrology Unit, Hadassah Medical Center and Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel
- Wohl Institute for Translational Medicine, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
- Department of Nephrology, Hadassah Medical Center and Faculty of Medicine, Hebrew University of Jerusalem, Jerusalem, Israel
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion – Israel Institute of Technology, Haifa, Israel
- Laboratory of Medical Transcriptomics, Department of Nephrology and Hypertension and Internal Medicine B, Hadassah – Hebrew University Medical Center, Jerusalem, Israel.
Abstract:
Cystic kidney disease is a leading cause of morbidity in patients with tuberous sclerosis complex (TSC). We characterize the misregulated metabolic pathways using cell lines, a TSC mouse model, and human kidney sections. Our study reveals a substantial perturbation in the arginine biosynthesis pathway in TSC models with overexpression of argininosuccinate synthetase 1 (ASS1). The rise in ASS1 expression is dependent on the mechanistic target of rapamycin complex 1 (mTORC1) activity. Arginine depletion prevents mTORC1 hyperactivation and cell cycle progression and averts cystogenic signaling overexpression of c-Myc and P65. Accordingly, an arginine-depleted diet substantially reduces the TSC cystic load in mice, indicating the potential therapeutic effects of arginine deprivation for the treatment of TSC-associated kidney disease.
Major findings:
Cystic kidney disease is a leading cause of chronic kidney disease (CKD) in patients with TSC disease. Here we studied the metabolic changes in TSC kidneys mouse model and especially in proximal tubule cells (PTCs), and demonstrated that arginine metabolism has a crucial role in the pathogenesis of TSC cystic kidney disease. We show that:
- Tsc1 ablation in the kidney, leads to dramatic changes in a substantial number of metabolites and to perturbations in significant metabolic pathways. mTOR inhibition during pregnancy by rapamycin, reversed metabolic changes, secondary to mTORC1 hyperactivation. However, some metabolites remained unresponsive to mTORC1 inhibition, indicating that, in part, these metabolic changes are mTORC1 independent. The metabolic changes were observed in whole kidney extracts and more so in sorted PTCs.
- Our metabolomic and bioinformatic analysis identified changes in arginine metabolism and overexpression of ASS1, a rate-limiting enzyme in the arginine biosynthetic pathway. These changes were observed in transcript and protein levels both in vitro in a human cell line of PTCs and in vivo in mouse and human TSC sections. The increase in ASS1 levels correlated and affected by mTORC1 activity, as demonstrated by a decrease in ASS1 levels upon rapamycin treatment.
- Arginine depletion in PTCs prevented the activation of signaling pathways previously shown to contribute to the cystogenic process, such as c-Myc and P65. Arginine depletion also prevented the increase in mTORC1 activity and pathogenic changes in the cell cycle. More importantly, feeding pregnant mice carrying TSC embryos with an arginine-depleted diet, substantially reduced the TSC cystic load, along with a decline in mTORC1 activity and cystogenic pathways as c-Myc and P65 expression and macrophage infiltration.
Our findings suggest that targeting arginine metabolism may alleviate TSC-associated cystogenesis by derangement of the TSC-associated cell signaling in PTCs via a reduction in mTORC1, c-Myc, and P65 signaling, lessening the inflammatory response and decreasing cystic cell proliferation, and could be relevant in treating TSC-associated kidney disease.