mTORC1 maintains renal tubular homeostasis and is essential in response to ischemic stress

Area of Science:

• Nephrology
• Cell Biology
• Molecular Biology

Background:

• Mammalian target of rapamycin complex 1 (mTORC1) regulates cell metabolism and autophagy.
• The specific role of mTORC1 in renal tubular function and kidney homeostasis is not well understood.
• mTORC1 inhibitors are clinically used, highlighting the importance of understanding mTORC1 pathways.

Purpose of the Study:

• To investigate the role of mTORC1 in renal tubular epithelial cells.
• To determine the impact of mTORC1 deficiency on kidney homeostasis and response to injury.
• To elucidate the molecular mechanisms by which mTORC1 influences renal tubular function.

Main Methods:

• Used constitutive and inducible deletion of conditional Raptor alleles in renal tubular epithelial cells.
• Performed transcriptional profiling to analyze gene expression changes.
• Exposed mTORC1-deficient mice to ischemia and reperfusion injury.

Main Results:

• mTORC1 deficiency led to impaired urine concentrating ability, tubular cell loss, and progressive renal fibrosis.
• Transcriptional analysis indicated mTORC1 controls mitochondrial metabolism, biogenesis, and transcellular transport in tubules.
• mTORC1-deficient mice showed exacerbated tubular damage, increased apoptosis, and reduced proliferation after ischemic injury.
• mTORC2 partially compensated for mTORC1 loss, but did not prevent severe injury outcomes.

Conclusions:

• mTORC1 is essential for maintaining renal tubular homeostasis and function.
• mTORC1 plays a critical role in regulating tubular energy metabolism and mitochondrial function.
• mTORC1 is a key component of the kidney's response to ischemic stress, influencing repair and recovery.
• Targeting mTORC1 pathways may have implications for treating kidney diseases involving metabolic dysfunction or injury.