The RNA-binding protein AUF1 facilitates Akt phosphorylation at the membrane

Li, Mei-Ling; Ragupathi, Aparna; Patel, Nikhil; Hernández, Tatiana; Magsino, Jedrick; Werlen, Guy; Brewer, Gary; Jacinto, Estela

doi:10.1016/j.jbc.2022.102437

Cited by 4 publications

(5 citation statements)

References 71 publications

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“…However, it is not known whether the DMA-135 effect is specific for SLII or whether it extends to endogenous, cellular AUF1 target mRNAs. Hence, qRT-PCR analyses of the originally purified RNA samples from RIPs performed with nonimmune or AUF1 antibody were extended to include three randomly chosen cellular mRNAs bound by AUF1: proto-oncogene MYC , GFAT1 (glutamine fructose-6-phosphate amidotransferase 1), and the mammalian target of rapamycin complex 2 (mTORC2) component, rictor ( 27 ). Glyceraldehyde-3-phosphate dehydrogenase ( GAPDH ) mRNA, which is not an AUF1 target, served as a negative control.…”

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…As a control experiment, immunoprecipitation of endogenous protein-RNA complexes and qRT-PCR were used to examine the effects of DMA-135 on association of AUF1 with examples of its endogenous mRNA targets as previously described (15). The RNA samples analyzed in the present work were the same RNA samples used in our earlier study (15), except we measured the effects of DMA-135 on AUF1 association with cellular mRNAs MYC, GFAT1, and rictor (mTORC2 subunit); GAPDH mRNA served as a nonbound mRNA control (27). RNAs were analyzed by qRT-PCR using the following primer sets: MYC (forward: 5′-acgaaactttgcccatagca-3′; reverse: 5′-gcaaggagagcctttcagag-3′); GFAT1 (forward:5′-ccccagtcccacagaagtat-3′; reverse: 5′-aactgacagcattggctttg-3′); rictor (forward: 5′-ctaggtggca-ttgacattcagc-3′; reverse: 5′-ctaggaaacaaggaagcattcag-3′); and GAP-DH (forward: 5′-gattgttgccatcaacgacc-3′; reverse: 5′-ccatggtggtgaagacacca-3′).…”

Section: Dual Luciferase Reporter Assaymentioning

confidence: 99%

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Enterovirus evolution reveals the mechanism of an RNA-targeted antiviral and determinants of viral replication

Davila-Calderon,

Li,

Penumutchu

et al. 2024

Sci. Adv.

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Selective pressures on viruses provide opportunities to establish target site specificity and mechanisms of antivirals. Enterovirus (EV)-A71 with resistant mutations in the stem loop (SL) II internal ribosome entry site (IRES) (SLII resist ) were selected at low doses of the antiviral dimethylamiloride (DMA)-135. The EV-A71 mutants were resistant to DMA-135 at concentrations that inhibit replication of wild-type virus. EV-A71 IRES structures harboring resistant mutations induced efficient expression of Luciferase messenger RNA in the presence of noncytotoxic doses of DMA-135. Nuclear magnetic resonance indicates that the mutations change the structure of SLII at the binding site of DMA-135 and at the surface recognized by the host protein AU-rich element/poly(U)-binding/degradation factor 1 (AUF1). Biophysical studies of complexes formed between AUF1, DMA-135, and either SLII or SLII resist show that DMA-135 stabilizes a ternary complex with AUF1-SLII but not AUF1-SLII resist . This work demonstrates how viral evolution elucidates the (DMA-135)–RNA binding site specificity in cells and provides insights into the viral pathways inhibited by the antiviral.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Dual Luciferase Reporter Assaymentioning

confidence: 99%

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Enterovirus evolution reveals the mechanism of an RNA-targeted antiviral and determinants of viral replication

Davila-Calderon,

Li,

Penumutchu

et al. 2024

Sci. Adv.

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“…An RNA processing and ribosome biogenesis protein, SMN (survival motor neuron), also associates with mTOR transcript and its deficiency is linked to increased nuclear retention of mTOR mRNA [ 77 ]. Another RNA-binding protein AUF1 also associates with mRNAs of mTORC2 components including mTOR, rictor, and SIN1 as well as the mTORC2 targets Akt and GFAT1 [ 78 ]. It remains unclear how AUF1 could modulate mTORC2 levels or signaling.…”

Section: Transcriptional Regulation Of Mtorc2mentioning

confidence: 99%

The mTORC2 signaling network: targets and cross-talks

Ragupathi,

Kim,

Jacinto

2024

Biochemical Journal

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The mechanistic target of rapamycin, mTOR, controls cell metabolism in response to growth signals and stress stimuli. The cellular functions of mTOR are mediated by two distinct protein complexes, mTOR complex 1 (mTORC1) and mTORC2. Rapamycin and its analogs are currently used in the clinic to treat a variety of diseases and have been instrumental in delineating the functions of its direct target, mTORC1. Despite the lack of a specific mTORC2 inhibitor, genetic studies that disrupt mTORC2 expression unravel the functions of this more elusive mTOR complex. Like mTORC1 which responds to growth signals, mTORC2 is also activated by anabolic signals but is additionally triggered by stress. mTORC2 mediates signals from growth factor receptors and G-protein coupled receptors. How stress conditions such as nutrient limitation modulate mTORC2 activation to allow metabolic reprogramming and ensure cell survival remains poorly understood. A variety of downstream effectors of mTORC2 have been identified but the most well-characterized mTORC2 substrates include Akt, PKC, and SGK, which are members of the AGC protein kinase family. Here, we review how mTORC2 is regulated by cellular stimuli including how compartmentalization and modulation of complex components affect mTORC2 signaling. We elaborate on how phosphorylation of its substrates, particularly the AGC kinases, mediates its diverse functions in growth, proliferation, survival, and differentiation. We discuss other signaling and metabolic components that cross-talk with mTORC2 and the cellular output of these signals. Lastly, we consider how to more effectively target the mTORC2 pathway to treat diseases that have deregulated mTOR signaling.

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“…Thus, when nutrients are acutely limited or cellular demand is high, the HBP would need to be tightly regulated to restore metabolic homeostasis, arguing for a positive regulatory role for GFAT1 Ser243 phosphorylation. The RNA-binding protein AUF1, which controls mRNA stability and the expression of several genes including Gfpt1 , is also involved in promoting GFAT1 Ser243 phosphorylation [ 35 ]. Since AUF1 is positively modulated by signals that enhance mTORC2 activation, these findings underscore the role of mTORC2 in modulating GFAT1 expression and Ser243 phosphorylation.…”

Section: De Novo Hexosamine Biosynthesismentioning

confidence: 99%

The Hexosamine Biosynthesis Pathway: Regulation and Function

Paneque

Fortus

Zheng

et al. 2023

Genes

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The hexosamine biosynthesis pathway (HBP) produces uridine diphosphate-N-acetyl glucosamine, UDP-GlcNAc, which is a key metabolite that is used for N- or O-linked glycosylation, a co- or post-translational modification, respectively, that modulates protein activity and expression. The production of hexosamines can occur via de novo or salvage mechanisms that are catalyzed by metabolic enzymes. Nutrients including glutamine, glucose, acetyl-CoA, and UTP are utilized by the HBP. Together with availability of these nutrients, signaling molecules that respond to environmental signals, such as mTOR, AMPK, and stress-regulated transcription factors, modulate the HBP. This review discusses the regulation of GFAT, the key enzyme of the de novo HBP, as well as other metabolic enzymes that catalyze the reactions to produce UDP-GlcNAc. We also examine the contribution of the salvage mechanisms in the HBP and how dietary supplementation of the salvage metabolites glucosamine and N-acetylglucosamine could reprogram metabolism and have therapeutic potential. We elaborate on how UDP-GlcNAc is utilized for N-glycosylation of membrane and secretory proteins and how the HBP is reprogrammed during nutrient fluctuations to maintain proteostasis. We also consider how O-GlcNAcylation is coupled to nutrient availability and how this modification modulates cell signaling. We summarize how deregulation of protein N-glycosylation and O-GlcNAcylation can lead to diseases including cancer, diabetes, immunodeficiencies, and congenital disorders of glycosylation. We review the current pharmacological strategies to inhibit GFAT and other enzymes involved in the HBP or glycosylation and how engineered prodrugs could have better therapeutic efficacy for the treatment of diseases related to HBP deregulation.

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The RNA-binding protein AUF1 facilitates Akt phosphorylation at the membrane

Cited by 4 publications

References 71 publications

Enterovirus evolution reveals the mechanism of an RNA-targeted antiviral and determinants of viral replication

Enterovirus evolution reveals the mechanism of an RNA-targeted antiviral and determinants of viral replication

The mTORC2 signaling network: targets and cross-talks

The Hexosamine Biosynthesis Pathway: Regulation and Function

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