CARS senses cysteine deprivation to activate AMPK for cell survival

Abstract

Adenosine 5'‐monophosphate (AMP)‐activated protein kinase (AMPK) is an important cellular metabolite‐sensing enzyme that can directly sense changes not only in ATP but also in metabolites associated with carbohydrates and fatty acids. However, less is known about whether and how AMPK senses variations in cellular amino acids. Here, we show that cysteine deficiency significantly triggers calcium/calmodulin‐dependent protein kinase kinase 2 (CaMKK2)‐mediated activation of AMPK. In addition, we found that CaMKK2 directly associates with cysteinyl‐tRNA synthetase (CARS), which then binds to AMPKγ2 under cysteine deficiency to activate AMPK. Interestingly, we discovered that cysteine inhibits the binding of CARS to AMPKγ2, and thus, under cysteine deficiency conditions wherein the inhibitory effect of cysteine is abrogated, CARS mediates the binding of AMPK to CaMKK2, resulting in the phosphorylation and activation of AMPK by CaMKK2. Importantly, we demonstrate that blocking AMPK activation leads to cell death under cysteine‐deficient conditions. In summary, our study is the first to show that CARS senses the absence of cysteine and activates AMPK through the cysteine–CARS–CaMKK2–AMPKγ2 axis, a novel adaptation strategy for cell survival under nutrient deprivation conditions.

AMPK CA(R)Sts a new light on amino acid sensing

“…In addition to its role in protein synthesis, the sulfur‐containing amino acid cysteine is critical in many biological processes including synthesis of coenzyme A, iron–sulfur (Fe‐S) cluster biogenesis and redox balance (Combs & DeNicola, 2019). In the current study, Yuan et al (2021) demonstrate that cysteine deprivation promotes a rapid and marked activation of AMPK. AMPK is a heterotrimeric protein complex composed of a catalytic α‐subunit and two regulatory subunits, β and γ.…”

“…In addition to its role in protein synthesis, the sulfur-containing amino acid cysteine is critical in many biological processes including synthesis of coenzyme A, iron-sulfur (Fe-S) cluster biogenesis and redox balance (Combs & DeNicola, 2019). In the current study, Yuan et al (2021) demonstrate that cysteine deprivation promotes a rapid and marked activation of AMPK. AMPK is a heterotrimeric protein complex composed of a catalytic a-subunit and two regulatory subunits, b and c. In mammals, there are two isoforms of a, two of b and three of c. AMPK activation is induced upon phosphorylation of residue Thr172 in the AMPK a-subunit (by liver kinase B1, LKB1; calcium/calmodulindependent protein kinase kinase 2, CaMKK2; or transforming growth factor-b-activated kinase 1, TAK1).…”

“…Importantly, the activation of AMPK in this context was shown to be independent of the GCN2 pathway. Yuan et al (2021) go on to show that CaMKK2 interacts with the cysteine‐specific AARS cysteinyl‐tRNA synthetase (CARS). In response to cysteine deprivation, when CARS ceases to bind cysteine, CARS interacts with the γ2‐subunit of AMPK to bring CARS‐bound CaMKK2 into close proximity with the AMPK complex.…”

Mitochondrion-Localized SND1 Promotes Mitophagy and Liver Cancer Progression Through PGAM5

“…The sample was prepared according to a preparation kit (Thermo: 90057), and LC-MS and data analysis were performed following the procedure described previously ( 23 , 24 ). A Q-Exactive Plus mass spectrometer (Thermo) coupled to an EASY-nLC 1200 HPLC system (Thermo) with an anoelectrospray ion source and operated in data-dependent mode was used to analyze the samples.…”

N-Acetyl-Cysteine: Modulating the Cysteine Redox Proteome in Neurodegenerative Diseases

“…Recent investigations have shown that cysteine depletion activates AMPK through calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2). Interestingly, the cysteinyl-tRNA synthetase (CARS), which plays a canonical role in protein translation, recognizes lack of cysteines and activates AMPK via the cysteine–CARS–CaMKK2–AMPKg2 system, adapting cell survival to nutrient deprivation [ 282 ]. Mitochondrial CARSs in human cells are involved in endogenous cysteine hydropersulfide (CysSSH) synthesis in vivo and even catalyze co-translational cysteine polysulfidation, which are implicated in the modulation of mitochondrial biogenesis and bioenergetics, playing a central role in redox signaling, cellular translation, and energy metabolism [ 283 ].…”