Dataset Information

PRMT5-mediated arginine methylation activates AKT kinase to govern tumorigenesis

ABSTRACT: AKT is involved in a number of key cellular processes including cell proliferation, apoptosis and metabolism. Hyperactivation of AKT is associated with many pathological conditions, particularly cancers. Emerging evidence indicates that arginine methylation is involved in modulating AKT signaling pathway. However, whether and how arginine methylation directly regulates AKT kinase activity remain unknown. Here we report that protein arginine methyltransferase 5 (PRMT5), but not other PRMTs, promotes AKT activation by catalyzing symmetric dimethylation of AKT1 at arginine 391 (R391). Mechanistically, AKT1-R391 methylation cooperates with phosphatidylinositol 3,4,5 trisphosphate (PIP3) to relieve the pleckstrin homology (PH)-in conformation, leading to AKT1 membrane translocation and subsequent activation by phosphoinositide-dependent kinase-1 (PDK1) and the mechanistic target of rapamycin complex 2 (mTORC2). As a result, deficiency in AKT1-R391 methylation significantly suppresses AKT1 kinase activity and tumorigenesis. Lastly, we show that PRMT5 inhibitor synergizes with AKT inhibitor or chemotherapeutic drugs to enhance cell death. Altogether, our study suggests that R391 methylation is an important step for AKT activation and its oncogenic function.

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): T Cell

SUBMITTER: Jennifer Bethard

LAB HEAD: Wenjian Gan, Ph.D.

PROVIDER: PXD026071 | Pride | 2022-02-17

REPOSITORIES: Pride

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PRMT5-mediated arginine methylation activates AKT kinase to govern tumorigenesis.

Yin Shasha S Liu Liu L Brobbey Charles C Palanisamy Viswanathan V Ball Lauren E LE Olsen Shaun K SK Ostrowski Michael C MC Gan Wenjian W

Nature communications 20210608 1

AKT is involved in a number of key cellular processes including cell proliferation, apoptosis and metabolism. Hyperactivation of AKT is associated with many pathological conditions, particularly cancers. Emerging evidence indicates that arginine methylation is involved in modulating AKT signaling pathway. However, whether and how arginine methylation directly regulates AKT kinase activity remain unknown. Here we report that protein arginine methyltransferase 5 (PRMT5), but not other PRMTs, promo ...[more]

PMID: 34103528

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Project description:To directly observe the conformational changes in Akt1 3P elicited by PIP 3 binding, we performed HDX-MS analysis of Akt1 3P in the presence of plasma membrane-mimicking liposomes (20% cholesterol, 30% phosphatidylcholine, 15% phosphatidylserine, 35% phosphatidylethanolamine) that contained either 0% or 5% PIP 3 . The sequence coverage of Akt1 was excellent, with 160 peptides spanning ~97% of all exchangeable amides (Supplementary Table 2). With 5% PIP 3 liposomes there was extensive protection of the PH domain, similar to what had been previously observed for non-phosphorylated Akt1. In addition to protection of the PH domain elicited by PIP 3 binding, Akt1 3P exhibited significant deprotection of the C-lobe of the kinase domain, including the activation loop, that corresponds to the interface between the PH and kinase domains observed in our structure of autoinhibited Akt1. We also carriedout HDX-MS experiments in the presence and absence of ATPS, for which we observed no significant differences. The likely binding pocket for the hydrophobic motif is the so-called PDK1- interacting fragment (PIF) pocket in Akt that binds the phosphorylated hydrophobic motif in the active conformation (21, 22) . Previous hydrogen- deuterium exchange mass spectrometry (HDX-MS) analysis of Akt1 DrLink indicated small, but significant exposure of the PIF pocket upon PI(3,4,5)P 3 binding (26) (Figure 5D, deuterium incorporation plots reproduced with permission). We confirmed this observation by comparing the deuterium incorporation rates for Akt1 DrLink and Akt1 ΔC in solution. Sequence coverage of the truncated Akt1 ΔC comprised 85 peptides spanning ~94% of all exchangeable amides (Supplementary Table 2). Two peptides in Akt1 ΔC , corresponding to β3-αB in the N-lobe and the catalytic loop in the C-lobe of the kinase domain exhibited a modest, but significant, 6% increase in deuterium incorporation (Figure 5E). These changes indicate exposure of the PIF pocket and consequent local disordering of the N-lobe in the absence of the hydrophobic motif. These observationsis areis consistent with the lack of electron density observed for theC helix and activation loop and overall higher temperature factors for the N- lobe of the kinase domain (Supplementary Figure S5CD). In order to test whether the unphosphorylated hydrophobic motif indeed binds to the PIF pocket in the inactive conformation, we measured the binding affinity of a tail peptide 19 containing the missing C-terminal tail residues in Akt1 ΔC (residues 457-480 of human Akt1) by fluorescence anisotropy. The binding constant was estimated to be approximately 0.5 mM from three independent titrations (Figure 5F), although it was not possible to reach saturation due to limiting Akt1 ΔC concentration. Whilst this is a relatively weak interaction, it is sufficient in the context of an intramolecular interaction to sequester the hydrophobic motif more than 99% of the time at equilibrium due to the almost infinite local concentration.

			Action	DRS
	110819_WenjianGan_AKT1.msf	Msf
	110819_WenjianGan_AKT1.raw	Raw
	AKT1.fasta	Fasta
	Methyl__R_Sites.txt	Txt
	checksum.txt	Txt