Altered mTOR signalling in nephropathic cystinosis.

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• Lysosomes regulate autophagy through mammalian target of rapamycin complex 1 (mTORC1) activation.
• Nephropathic cystinosis, a lysosomal storage disease, exhibits accumulation of autophagy markers.
• Cystinosis results from cystinosin mutations, leading to kidney proximal tubule dysfunction and end-stage renal disease.

Purpose of the Study:

• To investigate mTORC1 signaling in nephropathic cystinosis.
• To determine the impact of cystinosin deficiency on mTORC1 pathway dynamics.
• To explore potential therapeutic targets within mTORC1-dependent signaling cascades.

Main Methods:

• Analysis of mTORC1 signaling in kidney proximal tubular cells from healthy donors and cystinosis patients.
• Assessment of mTORC1 reactivation after starvation.
• Evaluation of lysosomal mTOR localization during starvation.
• Testing the efficacy of cysteamine treatment on mTORC1 signaling.

Main Results:

• Cystinosis is associated with perturbed mTORC1 signaling.
• Delayed reactivation of mTORC1 was observed after starvation in cystinotic cells.
• Abnormal lysosomal retention of mTOR occurred during starvation.
• Cysteamine treatment did not reverse these mTORC1 signaling alterations.

Conclusions:

• Cystinosin deficiency impairs mTORC1 signaling and lysosomal function.
• Altered mTORC1 signaling contributes to proximal tubular dysfunction in cystinosis.
• Modulation of mTORC1 signaling presents a potential therapeutic strategy for cystinosis.