RESUMEN
Despite the importance of glucose and amino acids for energy metabolism, interactions between the two nutrients are not well understood. We provide evidence for a role of leucyl-tRNA synthetase 1 (LARS1) in glucose-dependent control of leucine usage. Upon glucose starvation, LARS1 was phosphorylated by Unc-51 like autophagy activating kinase 1 (ULK1) at the residues crucial for leucine binding. The phosphorylated LARS1 showed decreased leucine binding, which may inhibit protein synthesis and help save energy. Leucine that is not used for anabolic processes may be available for catabolic pathway energy generation. The LARS1-mediated changes in leucine utilization might help support cell survival under glucose deprivation. Thus, depending on glucose availability, LARS1 may help regulate whether leucine is used for protein synthesis or energy production.
Asunto(s)
Metabolismo Energético , Glucosa/metabolismo , Leucina-ARNt Ligasa/metabolismo , Leucina/metabolismo , Animales , Homólogo de la Proteína 1 Relacionada con la Autofagia/genética , Homólogo de la Proteína 1 Relacionada con la Autofagia/metabolismo , Fibroblastos , Células HEK293 , Células HeLa , Humanos , Lisosomas/metabolismo , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Ratones , Proteínas de Unión al GTP Monoméricas/metabolismo , Fosforilación , Transducción de SeñalRESUMEN
Leucyl-tRNA synthetase (LRS) is known to function as leucine sensor in the mammalian target of rapamycin complex 1 (mTORC1) pathway. However, the pathophysiological significance of its activity is not well understood. Here, we demonstrate that the leucine sensor function for mTORC1 activation of LRS can be decoupled from its catalytic activity. We identified compounds that inhibit the leucine-dependent mTORC1 pathway by specifically inhibiting the GTPase activating function of LRS, while not affecting the catalytic activity. For further analysis, we selected one compound, BC-LI-0186, which binds to the RagD interacting site of LRS, thereby inhibiting lysosomal localization of LRS and mTORC1 activity. It also effectively suppressed the activity of cancer-associated MTOR mutants and the growth of rapamycin-resistant cancer cells. These findings suggest new strategies for controlling tumor growth that avoid the resistance to existing mTOR inhibitors resulting from cancer-associated MTOR mutations.Leucyl-tRNA synthetase (LRS) is a leucine sensor of the mTORC1 pathway. Here, the authors identify inhibitors of the GTPase activating function of LRS, not affecting its catalytic activity, and demonstrate that the leucine sensor function of LRS can be a new target for mTORC1 inhibition.
Asunto(s)
Leucina-ARNt Ligasa/metabolismo , Leucina/metabolismo , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Proteínas de Unión al GTP Monoméricas/metabolismo , Neoplasias/enzimología , Animales , Antineoplásicos/farmacología , Línea Celular Tumoral , Ensayos de Selección de Medicamentos Antitumorales , Femenino , Humanos , Leucina-ARNt Ligasa/genética , Diana Mecanicista del Complejo 1 de la Rapamicina/genética , Ratones , Ratones Endogámicos BALB C , Ratones Desnudos , Proteínas de Unión al GTP Monoméricas/genética , Neoplasias/genética , Neoplasias/metabolismo , Unión Proteica/efectos de los fármacos , Transducción de Señal/efectos de los fármacos , Sirolimus/farmacologíaRESUMEN
Leucyl-tRNA synthetase (LRS) has been reported to be a possible mediator of intracellular amino acids signaling to mTORC1. Given that mTORC1 is associated with cell proliferation and tumorigenesis, the LRS-mediated mTORC1 pathway may offer an alternative strategy in anticancer therapy. In this study, we developed a series of simplified analogues of leucyladenylate sulfamate (1) as LRS-targeted mTORC1 inhibitors. We replaced the adenylate group with a N-(3,4-dimethoxybenzyl)benzenesulfonamide (2a) or a N-(2-phenoxyethyl)benzenesulfonamide groups (2b) that can maintain specific binding, but has more favorable physicochemical properties such as reduced polarity and asymmetric centers. Among these simplified analogues, compound 16 and its constrained analogue 22 effectively inhibited S6K phosphorylation in a dose-dependent manner and exhibited cancer cell specific cytotoxicity against six different types of cancer cells. This result supports that LRS is a viable target for novel anticancer therapy.
Asunto(s)
Descubrimiento de Drogas , Leucina-ARNt Ligasa/metabolismo , Diana Mecanicista del Complejo 1 de la Rapamicina/antagonistas & inhibidores , Ácidos Sulfónicos/química , Ácidos Sulfónicos/farmacología , Línea Celular Tumoral , Ensayos de Selección de Medicamentos Antitumorales , Células HEK293 , Humanos , Espectrometría de Masas/métodos , Fosforilación , Espectroscopía de Protones por Resonancia Magnética , Proteínas Quinasas S6 Ribosómicas/metabolismoRESUMEN
Recent studies indicate that LRS may act as a leucine sensor for the mTORC1 pathway, potentially providing an alternative strategy to overcome rapamycin resistance in cancer treatments. In this study, we developed leucyladenylate sulfamate derivatives as LRS-targeted mTORC1 inhibitors. Compound 18 selectively inhibited LRS-mediated mTORC1 activation and exerted specific cytotoxicity against colon cancer cells with a hyperactive mTORC1, suggesting that 18 may offer a novel treatment option for human colorectal cancer.
