Immuno-characterization of the switch of peptide elongation factors eEF1A-1/EF-1alpha and eEF1A-2/S1 in the central nervous system during mouse development

Face-valid phenotypes in a mouse model of the most common mutation in EEF1A2-related neurodevelopmental disorder

De novo heterozygous missense mutations in EEF1A2, encoding neuromuscular translation-elongation factor eEF1A2, are associated with developmental and epileptic encephalopathies. We used CRISPR/Cas9 to recapitulate the most common mutation, E122K, in mice. Although E122K heterozygotes were not observed to have convulsive seizures, they exhibited frequent electrographic seizures and EEG abnormalities, transient early motor deficits and growth defects. Both E122K homozygotes and Eef1a2-null mice developed progressive motor abnormalities, with E122K homozygotes reaching humane endpoints by P31. The null phenotype is driven by progressive spinal neurodegeneration; however, no signs of neurodegeneration were observed in E122K homozygotes. The E122K protein was relatively stable in neurons yet highly unstable in skeletal myocytes, suggesting that the E122K/E122K phenotype is instead driven by loss of function in muscle. Nevertheless, motor abnormalities emerged far earlier in E122K homozygotes than in nulls, suggesting a toxic gain of function and/or a possible dominant-negative effect. This mouse model represents the first animal model of an EEF1A2 missense mutation with face-valid phenotypes and has provided mechanistic insights needed to inform rational treatment design.

Local mitochondrial replication in the periphery of neurons requires the eEF1A1 protein and thetranslation of nuclear-encoded proteins

In neurons, it is commonly assumed that mitochondrial replication only occurs in the cell body, after which the mitochondria must travel to the neuron's periphery. However, while mitochondrial DNA replication has been observed to occur away from the cell body, the specific mechanisms involved remain elusive. Using EdU-labelling in mouse primary neurons, we developed a tool to determine the mitochondrial replication rate. Taking of advantage of microfluidic devices, we confirmed that mitochondrial replication also occurs locally in the periphery of neurons. To achieve this, mitochondria require de novo nuclear-encoded, but not mitochondrial-encoded protein translation. Following a proteomic screen comparing synaptic with non-synaptic mitochondria, we identified two elongation factors - eEF1A1 and TUFM - that were upregulated in synaptic mitochondria. We found that mitochondrial replication is impaired upon the downregulation of eEF1A1, and this is particularly relevant in the periphery of neurons.

Oncogenic activation of EEF1A2 expression: a journey from a putative to an established oncogene

Protein synthesis via translation is a central process involving several essential proteins called translation factors. Although traditionally described as cellular "housekeepers," multiple studies have now supported that protein initiation and elongation factors regulate cell growth, apoptosis, and tumorigenesis. One such translation factor is eukaryotic elongation factor 1 alpha 2 (EEF1A2), a member of the eukaryotic elongation factor family, which has a canonical role in the delivery of aminoacyl-tRNA to the A-site of the ribosome in a guanosine 5'-triphosphate (GTP)-dependent manner. EEF1A2 differs from its closely related isoform, EEF1A1, in tissue distribution. While EEF1A1 is present ubiquitously, EEF1A2 replaces it in specialized tissues. The reason why certain specialized tissues need to essentially switch EEF1A1 expression altogether with EEF1A2 remains to be answered. Abnormal "switch on" of the EEF1A2 gene in normal tissues is witnessed and is seen as a cause of oncogenic transformation in a wide variety of solid tumors. This review presents the journey of finding increased expression of EEF1A2 in multiple cancers, establishing molecular mechanism, and exploring it as a target for cancer therapy. More precisely, we have compiled studies in seven types of cancers that have reported EEF1A2 overexpression. We have discussed the effect of aberrant EEF1A2 expression on the oncogenic properties of cells, signaling pathways, and interacting partners of EEF1A2. More importantly, in the last part, we have discussed the unique potential of EEF1A2 as a therapeutic target. This review article gives an up-to-date account of EEF1A2 as an oncogene and can draw the attention of the scientific community, attracting more research.

Endogenous epitope tagging of eEF1A2 in mice reveals early embryonic expression of eEF1A2 and subcellular compartmentalisation of neuronal eEF1A1 and eEF1A2

All vertebrate species express two independently-encoded forms of translation elongation factor eEF1A. In humans and mice eEF1A1 and eEF1A2 are 92 % identical at the amino acid level, but the well conserved developmental switch between the two variants in specific tissues suggests the existence of important functional differences. Heterozygous mutations in eEF1A2 result in neurodevelopmental disorders in humans; the mechanism of pathogenicity is unclear, but one hypothesis is that there is a dominant negative effect on eEF1A1 during development. The high degree of similarity between the eEF1A proteins has complicated expression analysis in the past; here we describe a gene edited mouse line in which we have introduced a V5 tag in the gene encoding eEF1A2. Expression analysis using anti-V5 and anti-eEF1A1 antibodies demonstrates that, in contrast to the prevailing view that eEF1A2 is only expressed postnatally, it is expressed from as early as E11.5 in the developing neural tube. Two colour immunofluorescence also reveals coordinated switching between eEF1A1 and eEF1A2 in different regions of postnatal brain. Completely reciprocal expression of the two variants is seen in post-weaning mouse brain with eEF1A1 expressed in oligodendrocytes and astrocytes and eEF1A2 in neuronal soma. Although eEF1A1 is absent from neuronal cell bodies after development, it is widely expressed in axons. This expression does not appear to coincide with myelin sheaths originating from oligodendrocytes but rather results from localised translation within the axon, suggesting that both variants are transcribed in neurons but show completely distinct subcellular localisation at the protein level. These findings will form an underlying framework for understanding how missense mutations in eEF1A2 result in neurodevelopmental disorders.

Analysis of the Expression and Subcellular Distribution of eEF1A1 and eEF1A2 mRNAs during Neurodevelopment

Neurodevelopment is accompanied by a precise change in the expression of the translation elongation factor 1A variants from eEF1A1 to eEF1A2. These are paralogue genes that encode 92% identical proteins in mammals. The switch in the expression of eEF1A variants has been well studied in mouse motor neurons, which solely express eEF1A2 by four weeks of postnatal development. However, changes in the subcellular localization of eEF1A variants during neurodevelopment have not been studied in detail in other neuronal types because antibodies lack perfect specificity, and immunofluorescence has a low sensitivity. In hippocampal neurons, eEF1A is related to synaptic plasticity and memory consolidation, and decreased eEF1A expression is observed in the hippocampus of Alzheimer's patients. However, the specific variant involved in these functions is unknown. To distinguish eEF1A1 from eEF1A2 expression, we have designed single-molecule fluorescence in-situ hybridization probes to detect either eEF1A1 or eEF1A2 mRNAs in cultured primary hippocampal neurons and brain tissues. We have developed a computational framework, ARLIN (analysis of RNA localization in neurons), to analyze and compare the subcellular distribution of eEF1A1 and eEF1A2 mRNAs at specific developmental stages and in mature neurons. We found that eEF1A1 and eEF1A2 mRNAs differ in expression and subcellular localization over neurodevelopment, and eEF1A1 mRNAs localize in dendrites and synapses during dendritogenesis and synaptogenesis. Interestingly, mature hippocampal neurons coexpress both variant mRNAs, and eEF1A1 remains the predominant variant in dendrites.

The elongation factor eEF1A2 controls translation and actin dynamics in dendritic spines

Synaptic plasticity involves structural modifications in dendritic spines that are modulated by local protein synthesis and actin remodeling. Here, we investigated the molecular mechanisms that connect synaptic stimulation to these processes. We found that the phosphorylation of isoform-specific sites in eEF1A2-an essential translation elongation factor in neurons-is a key modulator of structural plasticity in dendritic spines. Expression of a nonphosphorylatable eEF1A2 mutant stimulated mRNA translation but reduced actin dynamics and spine density. By contrast, a phosphomimetic eEF1A2 mutant exhibited decreased association with F-actin and was inactive as a translation elongation factor. Activation of metabotropic glutamate receptor signaling triggered transient dissociation of eEF1A2 from its regulatory guanine exchange factor (GEF) protein in dendritic spines in a phosphorylation-dependent manner. We propose that eEF1A2 establishes a cross-talk mechanism that coordinates translation and actin dynamics during spine remodeling.

On the Need to Tell Apart Fraternal Twins eEF1A1 and eEF1A2, and Their Respective Outfits

eEF1A1 and eEF1A2 are paralogous proteins whose presence in most normal eukaryotic cells is mutually exclusive and developmentally regulated. Often described in the scientific literature under the collective name eEF1A, which stands for eukaryotic elongation factor 1A, their best known activity (in a monomeric, GTP-bound conformation) is to bind aminoacyl-tRNAs and deliver them to the A-site of the 80S ribosome. However, both eEF1A1 and eEF1A2 are endowed with multitasking abilities (sometimes performed by homo- and heterodimers) and can be located in different subcellular compartments, from the plasma membrane to the nucleus. Given the high sequence identity of these two sister proteins and the large number of post-translational modifications they can undergo, we are often confronted with the dilemma of discerning which is the particular proteoform that is actually responsible for the ascribed biochemical or cellular effects. We argue in this review that acquiring this knowledge is essential to help clarify, in molecular and structural terms, the mechanistic involvement of these two ancestral and abundant G proteins in a variety of fundamental cellular processes other than translation elongation. Of particular importance for this special issue is the fact that several de novo heterozygous missense mutations in the human EEF1A2 gene are associated with a subset of rare but severe neurological syndromes and cardiomyopathies.

Cell-type and fetal-sex-specific targets of prenatal alcohol exposure in developing mouse cerebral cortex

Prenatal alcohol exposure (PAE) results in cerebral cortical dysgenesis. Single-cell RNA sequencing was performed on murine fetal cerebral cortical cells from six timed pregnancies, to decipher persistent cell- and sex-specific effects of an episode of PAE during early neurogenesis. We found, in an analysis of 38 distinct neural subpopulations across 8 lineage subtypes, that PAE altered neural maturation and cell cycle and disrupted gene co-expression networks. Whereas most differentially regulated genes were inhibited, particularly in females, PAE also induced sex-independent neural expression of fetal hemoglobin, a presumptive epigenetic stress adaptation. PAE inhibited Bcl11a, Htt, Ctnnb1, and other upstream regulators of differentially expressed genes and inhibited several autism-linked genes, suggesting that neurodevelopmental disorders share underlying mechanisms. PAE females exhibited neural loss of X-inactivation, with correlated activation of autosomal genes and evidence for spliceosome dysfunction. Thus, episodic PAE persistently alters the developing neural transcriptome, contributing to sex- and cell-type-specific teratology.

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The neurogenic murine fetal cortex contains about 33 distinct cell subtypes

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Prenatal Alcohol Exposure (PAE) resulted in sex-specific alterations in developmental trajectory and cell cycle

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PAE females exhibited neural loss of X-inactivation and spliceosomal dysfunction

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PAE induced sex-independent neural expression of fetal hemoglobin gene transcripts

Structural Cues for Understanding eEF1A2 Moonlighting

Spontaneous mutations in the EEF1A2 gene cause epilepsy and severe neurological disabilities in children. The crystal structure of eEF1A2 protein purified from rabbit skeletal muscle reveals a post-translationally modified dimer that provides information about the sites of interaction with numerous binding partners, including itself, and maps these mutations onto the dimer and tetramer interfaces. The spatial locations of the side chain carboxylates of Glu301 and Glu374, to which phosphatidylethanolamine is uniquely attached via an amide bond, define the anchoring points of eEF1A2 to cellular membranes and interorganellar membrane contact sites. Additional bioinformatic and molecular modeling results provide novel structural insight into the demonstrated binding of eEF1A2 to SH3 domains, the common MAPK docking groove, filamentous actin, and phosphatidylinositol-4 kinase IIIβ. In this new light, the role of eEF1A2 as an ancient, multifaceted, and articulated G protein at the crossroads of autophagy, oncogenesis and viral replication appears very distant from the "canonical" one of delivering aminoacyl-tRNAs to the ribosome that has dominated the scene and much of the thinking for many decades.

Damaging de novo missense variants in EEF1A2 lead to a developmental and degenerative epileptic-dyskinetic encephalopathy

Heterozygous de novo variants in the eukaryotic elongation factor EEF1A2 have previously been described in association with intellectual disability and epilepsy but never functionally validated. Here we report 14 new individuals with heterozygous EEF1A2 variants. We functionally validate multiple variants as protein-damaging using heterologous expression and complementation analysis. Our findings allow us to confirm multiple variants as pathogenic and broaden the phenotypic spectrum to include dystonia/choreoathetosis, and in some cases a degenerative course with cerebral and cerebellar atrophy. Pathogenic variants appear to act via a haploinsufficiency mechanism, disrupting both the protein synthesis and integrated stress response functions of EEF1A2. Our studies provide evidence that EEF1A2 is highly intolerant to variation and that de novo pathogenic variants lead to an epileptic-dyskinetic encephalopathy with both neurodevelopmental and neurodegenerative features. Developmental features may be driven by impaired synaptic protein synthesis during early brain development while progressive symptoms may be linked to an impaired ability to handle cytotoxic stressors.

Expression pattern of EEF1A2 in brain tumors: Histological analysis and functional role as a promoter of EMT

AIMS

Glioblastomas are highly aggressive brain tumors with a very poor survival rate. EEF1A2, the proto-oncogenic isoform of the EEF1A translation factor family, has been found to be overexpressed and promoting tumorigenesis in multiple cancers. Interestingly, recent studies reported reduced expression of this protein in brain tumors, drawing our attention to find the functional role and mechanism of this protein in brain tumor progression.

MAIN METHODS

Using representative cell line as models, the role of EEF1A2 in cell proliferation, migration and invasion were assessed using MTS assay, scratch wound-healing assay, transwell migration and invasion assay, respectively. Activation of key signaling pathways was assessed using western blots and real-time PCR. Finally, using immunohistochemistry we checked the protein levels of EEF1A2 in CNS tumors.

KEY FINDINGS

EEF1A2 was found to increase the proliferative, migratory and invasive properties of cell lines of both glial and neuronal origin. PI3K activation directly correlated with EEF1A2 levels. Protein levels of key EMT markers viz. Twist, Snail, and Slug were increased upon ectopic EEF1A2 expression. Furthermore, EEF1A2 was found to affect the expression levels of key inflammatory cytokines, growth factors and matrix metalloproteases. IHC analysis showed that EEF1A2 is upregulated in tumor tissues compared to normal tissue.

SIGNIFICANCE

EEF1A2 acts as an oncogene in both neuronal and glial cells and triggers an EMT program via PI3K pathway. However, it shows enhanced expression in neuronal cells of the brain than the glial cells, which could explain the previously reported anomaly.

The expression profile and prognostic significance of eukaryotic translation elongation factors in different cancers

Eukaryotic translation factors, especially initiation factors have garnered much attention with regards to their role in the onset and progression of different cancers. However, the expression levels and prognostic significance of translation elongation factors remain poorly explored in different cancers. In this study, we have investigated the mRNA transcript levels of seven translation elongation factors in different cancer types using Oncomine and TCGA databases. Furthermore, we have identified the prognostic significance of these factors using Kaplan-Meier Plotter and SurvExpress databases. We observed altered expression levels of all the elongation factors in different cancers. Higher expression of EEF1A2, EEF1B2, EEF1G, EEF1D, EEF1E1 and EEF2 was observed in most of the cancer types, whereas reverse trend was observed for EEF1A1. Overexpression of many factors predicted poor prognosis in breast (EEF1D, EEF1E1, EEF2) and lung cancer (EEF1A2, EEF1B2, EEF1G, EEF1E1). However, we didn’t see any common correlation of expression levels of elongation factors with survival outcomes across cancer types. Cancer subtype stratification showed association of survival outcomes and expression levels of elongation factors in specific sub-types of breast, lung and gastric cancer. Most interestingly, we observed a reciprocal relationship between the expression levels of the two EEF1A isoforms viz. EEF1A1 and EEF1A2, in most of the cancer types. Our results suggest that translation elongation factors can have a role in tumorigenesis and affect survival in cancer specific manner. Elongation factors have potential to serve as biomarkers and therapeutic drug targets, yet further study is required. Reciprocal relationship of differential expression between EEF1A isoforms observed in multiple cancer types indicates opposing roles in cancer and needs further investigation.

Organ-specific adaptive signaling pathway activation in metastatic breast cancer cells

Breast cancer metastasizes to bone, visceral organs, and/or brain depending on the subtype, which may involve activation of a host organ-specific signaling network in metastatic cells. To test this possibility, we determined gene expression patterns in MDA-MB-231 cells and its mammary fat pad tumor (TMD-231), lung-metastasis (LMD-231), bone-metastasis (BMD-231), adrenal-metastasis (ADMD-231) and brain-metastasis (231-BR) variants. When gene expression between metastases was compared, 231-BR cells showed the highest gene expression difference followed by ADMD-231, LMD-231, and BMD-231 cells. Neuronal transmembrane proteins SLITRK2, TMEM47, and LYPD1 were specifically overexpressed in 231-BR cells. Pathway-analyses revealed activation of signaling networks that would enable cancer cells to adapt to organs of metastasis such as drug detoxification/oxidative stress response/semaphorin neuronal pathway in 231-BR, Notch/orphan nuclear receptor signals involved in steroidogenesis in ADMD-231, acute phase response in LMD-231, and cytokine/hematopoietic stem cell signaling in BMD-231 cells. Only NF-κB signaling pathway activation was common to all except BMD-231 cells. We confirmed NF-κB activation in 231-BR and in a brain metastatic variant of 4T1 cells (4T1-BR). Dimethylaminoparthenolide inhibited NF-κB activity, LYPD1 expression, and proliferation of 231-BR and 4T1-BR cells. Thus, transcriptome change enabling adaptation to host organs is likely one of the mechanisms associated with organ-specific metastasis and could potentially be targeted therapeutically.

MLIF Alleviates SH-SY5Y Neuroblastoma Injury Induced by Oxygen-Glucose Deprivation by Targeting Eukaryotic Translation Elongation Factor 1A2

Monocyte locomotion inhibitory factor (MLIF), a heat-stable pentapeptide, has been shown to exert potent anti-inflammatory effects in ischemic brain injury. In this study, we investigated the neuroprotective action of MLIF against oxygen-glucose deprivation (OGD)-induced injury in human neuroblastoma SH-SY5Y cells. MTT assay was used to assess cell viability, and flow cytometry assay and Hoechst staining were used to evaluate apoptosis. LDH assay was used to exam necrosis. The release of inflammatory cytokines was detected by ELISA. Levels of the apoptosis associated proteins were measured by western blot analysis. To identify the protein target of MLIF, pull-down assay and mass spectrometry were performed. We observed that MLIF enhanced cell survival and inhibited apoptosis and necrosis by inhibiting p-JNK, p53, c-caspase9 and c-caspase3 expression. In the microglia, OGD-induced secretion of inflammatory cytokines was markedly reduced in the presence of MLIF. Furthermore, we found that eukaryotic translation elongation factor 1A2 (eEF1A2) is a downstream target of MLIF. Knockdown eEF1A2 using short interfering RNA (siRNA) almost completely abrogated the anti-apoptotic effect of MLIF in SH-SY5Y cells subjected to OGD, with an associated decrease in cell survival and an increase in expression of p-JNK and p53. These results indicate that MLIF ameliorates OGD-induced SH-SY5Y neuroblastoma injury by inhibiting the p-JNK/p53 apoptotic signaling pathway via eEF1A2. Our findings suggest that eEF1A2 may be a new therapeutic target for ischemic brain injury.

Human eukaryotic elongation factor 1A forms oligomers through specific cysteine residues

Eukaryotic elongation factor 1A (eEF1A) is a multifunctional protein involved in bundling actin, severing microtubule, activating the phosphoinositol-4 kinase, and recruiting aminoacyl-tRNAs to ribosomes during protein biosynthesis. Although evidence has shown the presence of the isoform eEF1A1 oligomers, the substantial mechanism of the self-association remains unclear. Herein, we found that human eEF1A1 could spontaneously form oligomers. Specifically, mutagenesis screen on cysteine residues demonstrated that Cys(234) was essential for eEF1A1 oligomerization. In addition, we also found that hydrogen peroxide treatment could induce the formation of eEF1A oligomers in cells. By cysteine replacement, eEF1A2 isoform displayed the ability to oligomerize in cells under the oxidative environment. In summary, in this study we characterized eEF1A1 oligomerization and demonstrated that specific cysteine residues are required for this oligomerization activity.

Proto-oncogenic isoform A2 of eukaryotic translation elongation factor eEF1 is a target of miR-663 and miR-744

Background:

Eukaryotic translation elongation factor 1A2 (eEF1A2) is a known proto-oncogene. We proposed that stimulation of the eEF1A2 expression in cancer tissues is caused by the loss of miRNA-mediated control.

Methods:

Impact of miRNAs on eEF1A2 at the mRNA and protein levels was examined by qPCR and western blot, respectively. Dual-luciferase assay was applied to examine the influence of miRNAs on 3′-UTR of EEF1A2. To detect miRNA-binding sites, mutations into the 3′-UTR of EEF1A2 mRNA were introduced by the overlap extension PCR.

Results:

miR-663 and miR-744 inhibited the expression of luciferase gene attached to the 3′-UTR of EEF1A2 up to 20% and 50%, respectively. In MCF7 cells, overexpression of miR-663 and miR-744 reduced the EEF1A2 mRNA level by 30% and 50%. Analogous effects were also observed at the eEF1A2 protein level. In resveratrol-treated MCF7 cells the upregulation of mir-663 and mir-744 was accompanied by downregulation of EEF1A2 mRNA. Both miRNAs were able to inhibit the proliferation of MCF7 cells.

Conclusion:

miR-663 and miR-744 mediate inhibition of the proto-oncogene eEF1A2 expression that results in retardation of the MCF7 cancer cells proliferation. Antitumour effect of resveratrol may include stimulation of the miR-663 and miR-744 expression.

Loss of translation elongation factor (eEF1A2) expression in vivo differentiates between Wallerian degeneration and dying-back neuronal pathology

Wallerian degeneration and dying-back pathology are two well-known cellular pathways capable of regulating the breakdown and loss of axonal and synaptic compartments of neurons in vivo. However, the underlying mechanisms and molecular triggers of these pathways remain elusive. Here, we show that loss of translation elongation factor eEF1A2 expression in lower motor neurons and skeletal muscle fibres in homozygous Wasted mice triggered a dying-back neuropathy. Synaptic loss at the neuromuscular junction occurred in advance of axonal pathology and by a mechanism morphologically distinct from Wallerian degeneration. Dying-back pathology in Wasted mice was accompanied by reduced expression levels of the zinc finger protein ZPR1, as found in other dying-back neuropathies such as spinal muscular atrophy. Surprisingly, experimental nerve lesion revealed that Wallerian degeneration was significantly delayed in homozygous Wasted mice; morphological assessment revealed that approximately 80% of neuromuscular junctions in deep lumbrical muscles at 24 h and approximately 50% at 48 h had retained motor nerve terminals following tibial nerve lesion. This was in contrast to wild-type and heterozygous Wasted mice where < 5% of neuromuscular junctions had retained motor nerve terminals at 24 h post-lesion. These data show that eEF1A2 expression is required to prevent the initiation of dying-back pathology at the neuromuscular junction in vivo. In contrast, loss of eEF1A2 expression significantly inhibited the initiation and progression of Wallerian degeneration in vivo. We conclude that loss of eEF1A2 expression distinguishes mechanisms underlying dying-back pathology from those responsible for Wallerian degeneration in vivo and suggest that eEF1A2-dependent cascades may provide novel molecular targets to manipulate neurodegenerative pathways in lower motor neurons.

The human Y-encoded testis-specific protein interacts functionally with eukaryotic translation elongation factor eEF1A, a putative oncoprotein

Testis-specific protein Y-encoded (TSPY) is the putative gene for the gonadoblastoma locus on the Y chromosome. TSPY is expressed in normal germ cells of fetal and adult testis and ectopically in tumor germ cells, including gonadoblastoma in intersex patients, testicular germ cell tumors, prostate cancer and other somatic cancers. It is a member of the TSPY/SET/NAP1 superfamily and harbors a highly conserved domain, termed SET/NAP domain. To explore its possible role(s) in tumorigenesis, we had performed a yeast two-hybrid screen of a fetal gonadal cDNA library and identified the translation elongation factor eEF1A as a binding partner for TSPY at the SET/NAP domain. TSPY and eEF1A were highly expressed and colocalized in tumor germ cells of human seminoma specimens, suggesting their possible interaction in germ cell tumors. They were colocalized in the cytoplasm and could be co-immunoprecipitated from transfected COS7 cells. Significantly, both eEF1A1 and eEF1A2 have postulated to be involved in various types of human cancer, including breast and prostate cancers. TSPY enhanced protein synthesis of a reporter gene, which was augmented by an overexpression of eEF1A. TSPY also increased the nuclear redistribution of eEF1A, resulting in a parallel increase in reporter gene transcripts. Our results suggest that TSPY could exert its oncogenic function(s) by interacting with eEF1As and stimulating gene expression via its enhancements in protein synthesis and gene transcription.

Translation elongation factor eEF1A2 is essential for post-weaning survival in mice

Translation elongation factor eEF1A, formerly known as EF-1 alpha, exists as two variant forms; eEF1A1, which is almost ubiquitously expressed, and eEF1A2, whose expression is restricted to muscle and brain at the level of whole tissues. Expression analysis of these genes has been complicated by a general lack of availability of antibodies that specifically recognize each variant form. Wasted mice (wst/wst) have a 15.8-kilobase deletion that abolishes activity of eEF1A2, but before this study it was unknown whether the deletion also affected neighboring genes. We have generated a panel of anti-peptide antibodies and used them to show that eEF1A2 is expressed at high levels in specific cell types in tissues previously thought not to express this variant, such as pancreatic islet cells and enteroendocrine cells in colon crypts. Expression of eEF1A1 and eEF1A2 is shown to be generally mutually exclusive, and we relate the expression pattern of eEF1A2 to the phenotype seen in wasted mice. We then carried out a series of transgenic experiments to establish whether the expression of other genes is affected by the deletion in wasted mice. We show that aspects of the phenotype such as motor neuron degeneration relate precisely to the relative expression of eEF1A1 and eEF1A2, whereas the immune system abnormalities are likely to result from a stress response. We conclude that loss of eEF1A2 function is solely responsible for the abnormalities seen in these mice.

Elongation factor 1A family regulates the recycling of the M4 muscarinic acetylcholine receptor

In this study, we tested the hypothesis that the elongation 1A (eEF1A) family regulates the cell surface density of the M4 subtype of the muscarinic acetylcholine receptors (mAChR) following agonist-induced internalization. Here, we show that mouse brains lacking eEF1A2 have no detectable changes in M4 expression or localization. We, however, did discover that eEF1A1, the other eEF1A isoform, is expressed in adult neurons contrary to previous reports. This novel finding suggested that the lack of change in M4 expression and distribution in brains lacking eEF1A2 might be due to compensatory effects of eEF1A1. Supporting this theory, we demonstrate that the overexpression of either eEF1A1 or eEF1A2 inhibits M4 recovery to the cell surface after agonist-induced internalization in PC12 cells. Furthermore, eEF1A1 or eEF1A2 had no effect on the recovery of the M1 subtype in PC12 cells. These results demonstrate the novel ability of the eEF1A family to specifically regulate the M4 mAChR.