Follicular lymphoma–associated mutations in vacuolar ATPase ATP6V1B2 activate autophagic flux and mTOR
Fangyang Wang, Damián Gatica, Zhang Xiao Ying, Luke F. Peterson, Peter Kim, Denzil Bernard, Kamlai Saiya-Cork, Shaomeng Wang, Mark S. Kaminski, Alfred E. Chang, Tycel Phillips, Daniel J. Klionsky, Sami N. Malek
Fangyang Wang, Damián Gatica, Zhang Xiao Ying, Luke F. Peterson, Peter Kim, Denzil Bernard, Kamlai Saiya-Cork, Shaomeng Wang, Mark S. Kaminski, Alfred E. Chang, Tycel Phillips, Daniel J. Klionsky, Sami N. Malek
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Research Article Cell biology Oncology

Follicular lymphoma–associated mutations in vacuolar ATPase ATP6V1B2 activate autophagic flux and mTOR

Abstract

The discovery of recurrent mutations in subunits of the vacuolar-type H+-translocating ATPase (v-ATPase) in follicular lymphoma (FL) highlights a role for the amino acid– and energy-sensing pathway to mTOR in the pathogenesis of this disease. Here, through the use of complementary experimental approaches involving mammalian cells and Saccharomyces cerevisiae, we have demonstrated that mutations in the human v-ATPase subunit ATP6V1B2 (also known as Vma2 in yeast) activate autophagic flux and maintain mTOR/TOR in an active state. Engineered lymphoma cell lines and primary FL B cells carrying mutated ATP6V1B2 demonstrated a remarkable ability to survive low leucine concentrations. The treatment of primary FL B cells with inhibitors of autophagy uncovered an addiction for survival for FL B cells harboring ATP6V1B2 mutations. These data support the idea of mutational activation of autophagic flux by recurrent hotspot mutations in ATP6V1B2 as an adaptive mechanism in FL pathogenesis and as a possible new therapeutically targetable pathway.

Authors

Fangyang Wang, Damián Gatica, Zhang Xiao Ying, Luke F. Peterson, Peter Kim, Denzil Bernard, Kamlai Saiya-Cork, Shaomeng Wang, Mark S. Kaminski, Alfred E. Chang, Tycel Phillips, Daniel J. Klionsky, Sami N. Malek

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Figure 7

FL-associated ATP6V1B2 mutations and dependence on autophagic flux for survival of primary FL B cells.

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FL-associated ATP6V1B2 mutations and dependence on autophagic flux for s...
(A and B) Primary human purified FL B cells carrying WT or mutant ATP6V1B2 were cultured in serum-supplemented RPMI 1640 medium containing 100% leucine and treated with the ULK1 inhibitor MRT68921 for 72 hours at the indicated concentrations. Cell viability was measured using CellTiter-Glo and was normalized to the viability of cells cultured for 72 hours but left untreated. *P < 0.05, **P < 0.01, and ***P < 0.001 by t test, compared with results for WT at the same time point. Data represent the SD.