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Mayuri Patel
Pronouns
She/her
Rank
Institution
Brigham Womens Hospital
Department
Authors
Mayuri Patel, Dean M. Rosenthal, Nicola Alesi, Elizabeth P. Henske
Principal Investigator
Categories:
Introduction:
Lymphangioleiomyomatosis (LAM) is a rare lung condition observed in women of reproductive age. The disease can manifest sporadically in individuals without genetic predisposition, or in association with tuberous sclerosis complex (TSC). Tuberous sclerosis complex is an autosomal dominant disorder impacting multiple organ systems, arising from loss-of-function mutations in either TSC1 or TSC2 genes. The loss of TSC1/TSC2 function leads to the hyperactivation of the mechanistic target of rapamycin complex 1 (mTORC1) and consequent hypoactivation of the AKT signaling pathway. Our lab demonstrated that TSC1/2 deficient cells exhibit active and nuclear TFEB, a transcription factor responsible for the regulation of lysosomal biogenesis. TFEB nuclear localization results from defective phosphorylation. In TSC mouse models, TFEB is the primary driver of renal disease. Since both mTORC1 and AKT are known to directly phosphorylate TFEB, we sought to determine the importance of AKT in TFEB regulation in TSC-deficient cells.
Methods:
Hela TFEB-GFP cells (with and without KD of TSC2 by siRNA) and HEK293T sgCTRL cells and sgTSC2 cells, were treated with DMSO or MK2206 (AKT inhibitor) to assess TFEB nuclear localization and phosphorylation. We confirmed the data by inhibiting AKT1 genetically by siRNA.
Results:
TFEB nuclear localization is responsive to AKT inhibition by MK2206 in HeLa TFEB-GFP cells treated with siCTRL but not in the cells with TSC2 knockdown. Similarly, Inhibition of AKT with MK2206 reduced TFEB phosphorylation in HEK293T sgCTRL (2-fold) but not in sgTSC2 cells as well as in HeLa TFEB-GFP si CTRL (2-fold) but not in TSC2-deficient HeLa TFEB-GFP. The findings were confirmed using a genetic inhibition of AKT1 by SiRNA. Interestingly by knocking down AKT1 we also observed a decrease in TFEB total levels.
Conclusion:
We conclude that AKT hypoactivity in TSC is at least in part responsible for the hypo phosphorylation and consequent increased activity of TFEB.
