14-3-3 proteins are involved in the regulation of mammalian cell proliferation

Regulation of 14-3-3β/α gene expression in response to salinity, thermal, and bacterial stresses in Siberian sturgeon (Acipenser baeri)

The 14-3-3 proteins are a family of widely expressed acidic proteins, which are involved in the regulation of many biological processes of animals. However, no research regarding 14-3-3 has been described in sturgeon to date, one of the most primitive Actinopterygii species. Here, we identified the first 14-3-3 gene from Siberian sturgeon (Acipenser baeri), named Ab14-3-3β/α (GenBank Accession No. KY094076.1). The cDNA of Ab14-3-3β/α is 1212 bp in length, containing a 5'-untranslated region (UTR) of 82 bp, a 3'UTR of 392 bp, and an open reading frame (ORF) of 738 bp, encoding a polypeptide of 245 amino acids which contains a 14-3-3 homologs domain (PF00244). Phylogenetic analysis showed that the 14-3-3 gene product from Acipenser baeri is a counterpart of vertebrate 14-3-3β/α. The deduced Ab14-3-3β/α protein shares high identities of 46.5-95.5% with the homologs of other species. Ab14-3-3β/α mRNA was constitutively expressed in all examined tissues, with high expression levels in the blood and gill. Furthermore, the expression level of Ab14-3-3β/α mRNA increased significantly in the gill at 1 h under acute salinity shock by transfer of Siberian sturgeons from fresh water (FW) to 15 ppt. In fish subjected to a high temperature (31 °C), Ab14-3-3β/α showed a significant upregulation in the liver at 3 h compared with the control group (24 °C). A 4.85-fold increase of Ab14-3-3β/α expression in the spleen of Siberian sturgeon was observed at 24 h following Aeromonas hydrophila challenge. Collectively, these results indicated that Ab14-3-3β/α might play a certain role in sturgeon in response to some environmental stresses and bacterial challenge.

Molecular Atlas of Postnatal Mouse Heart Development

Background

The molecular mechanisms mediating postnatal loss of cardiac regeneration in mammals are not fully understood. We aimed to provide an integrated resource of mRNA, protein, and metabolite changes in the neonatal heart for identification of metabolism‐related mechanisms associated with cardiac regeneration.

Methods and Results

Mouse ventricular tissue samples taken on postnatal day 1 (P01), P04, P09, and P23 were analyzed with RNA sequencing and global proteomics and metabolomics. Gene ontology analysis, KEGG pathway analysis, and fuzzy c‐means clustering were used to identify up‐ or downregulated biological processes and metabolic pathways on all 3 levels, and Ingenuity pathway analysis (Qiagen) was used to identify upstream regulators. Differential expression was observed for 8547 mRNAs and for 1199 of 2285 quantified proteins. Furthermore, 151 metabolites with significant changes were identified. Differentially regulated metabolic pathways include branched chain amino acid degradation (upregulated at P23), fatty acid metabolism (upregulated at P04 and P09; downregulated at P23) as well as the HMGCS (HMG‐CoA [hydroxymethylglutaryl‐coenzyme A] synthase)–mediated mevalonate pathway and ketogenesis (transiently activated). Pharmacological inhibition of HMGCS in primary neonatal cardiomyocytes reduced the percentage of BrdU‐positive cardiomyocytes, providing evidence that the mevalonate and ketogenesis routes may participate in regulating the cardiomyocyte cell cycle.

Conclusions

This study is the first systems‐level resource combining data from genomewide transcriptomics with global quantitative proteomics and untargeted metabolomics analyses in the mouse heart throughout the early postnatal period. These integrated data of molecular changes associated with the loss of cardiac regeneration may open up new possibilities for the development of regenerative therapies.

Locomotor hyperactivity in 14-3-3ζ KO mice is associated with dopamine transporter dysfunction

Dopamine (DA) neurotransmission requires a complex series of enzymatic reactions that are tightly linked to catecholamine exocytosis and receptor interactions on pre- and postsynaptic neurons. Regulation of dopaminergic signalling is primarily achieved through reuptake of extracellular DA by the DA transporter (DAT) on presynaptic neurons. Aberrant regulation of DA signalling, and in particular hyperactivation, has been proposed as a key insult in the presentation of schizophrenia and related neuropsychiatric disorders. We recently identified 14-3-3ζ as an essential component of neurodevelopment and a central risk factor in the schizophrenia protein interaction network. Our analysis of 14-3-3ζ-deficient mice now shows that baseline hyperactivity of knockout (KO) mice is rescued by the antipsychotic drug clozapine. 14-3-3ζ KO mice displayed enhanced locomotor hyperactivity induced by the DA releaser amphetamine. Consistent with 14-3-3ζ having a role in DA signalling, we found increased levels of DA in the striatum of 14-3-3ζ KO mice. Although 14-3-3ζ is proposed to modulate activity of the rate-limiting DA biosynthesis enzyme, tyrosine hydroxylase (TH), we were unable to identify any differences in total TH levels, TH localization or TH activation in 14-3-3ζ KO mice. Rather, our analysis identified significantly reduced levels of DAT in the absence of notable differences in RNA or protein levels of DA receptors D1-D5. Providing insight into the mechanisms by which 14-3-3ζ controls DAT stability, we found a physical association between 14-3-3ζ and DAT by co-immunoprecipitation. Taken together, our results identify a novel role for 14-3-3ζ in DA neurotransmission and provide support to the hyperdopaminergic basis of pathologies associated with schizophrenia and related disorders.

Role of 14-3-3-beta in the migration and invasion in human malignant glioma cell line U87MG

PURPOSE

To assess the influence of 14-3-3-beta in modulating the migration and invasion of human glioma cells.

METHODS

To profile the genes associated with malignant glioma cell motility, differential display-polymerase chain reaction was performed and the findings were validated by Northern blotting in the U343MG-A, U87MG, and U87MG-10' human glioma cell lines. Antisense 14-3-3-beta cDNA plasmid was transfected into U87MG ('U87-YA-3'). To follow motility changes after transfection, simple scratch test and matrigel assay were performed. Morphological and cytoskeletal changes were documented by light and confocal microscopy. In addition, doubling times of the transfectant and endogenous 14-3-3-beta levels were determined in various glioma cell lines with different motilities.

RESULTS

14-3-3-beta was highly expressed in U87MG cells. U87-YA-3 cells became small and flat, and actin was depolarized. Furthermore, U87-YA-3 cell motility was inhibited markedly versus parental U87MG cells. The doubling times of transfected and parent cells were 32 and 37 hours, respectively. Endogenous 14-3-3-beta expression in the human glioma cell lines was proportional to their migratory and invasive abilities.

CONCLUSION

14-3-3-beta modulates the migration and invasion in U87MG cells, which may be useful in developing therapeutic approaches for the treatment of glioma.

Neurodevelopmental and neuropsychiatric behaviour defects arise from 14-3-3ζ deficiency

Complex neuropsychiatric disorders are believed to arise from multiple synergistic deficiencies within connected biological networks controlling neuronal migration, axonal pathfinding and synapse formation. Here, we show that deletion of 14-3-3ζ causes neurodevelopmental anomalies similar to those seen in neuropsychiatric disorders such as schizophrenia, autism spectrum disorder and bipolar disorder. 14-3-3ζ-deficient mice displayed striking behavioural and cognitive deficiencies including a reduced capacity to learn and remember, hyperactivity and disrupted sensorimotor gating. These deficits are accompanied by subtle developmental abnormalities of the hippocampus that are underpinned by aberrant neuronal migration. Significantly, 14-3-3ζ-deficient mice exhibited abnormal mossy fibre navigation and glutamatergic synapse formation. The molecular basis of these defects involves the schizophrenia risk factor, DISC1, which interacts isoform specifically with 14-3-3ζ. Our data provide the first evidence of a direct role for 14-3-3ζ deficiency in the aetiology of neurodevelopmental disorders and identifies 14-3-3ζ as a central risk factor in the schizophrenia protein interaction network.

Efficient ADAM22 surface expression is mediated by phosphorylation-dependent interaction with 14-3-3 protein family members

ADAM22 is one of three catalytically inactive ADAM family members highly expressed in the brain. ADAM22 has numerous splice variants, all with considerable cytoplasmic tails of up to 148 amino acids. ADAM22 can act to inhibit cell proliferation, however, it has been suggested that it also acts as an adhesion protein. We identified three 14-3-3 protein members by a yeast two-hybrid screen and show by co-immunoprecipitation that the cytoplasmic domain of ADAM22 can interact with all six 14-3-3 proteins expressed in the brain. In addition, we show that 14-3-3 proteins interact preferentially with the serine phosphorylated precursor form of ADAM22. ADAM22 has two 14-3-3 protein binding consensus motifs; the first binding site, spanning residues 831-834, was shown to be the most crucial for 14-3-3 binding to occur. The interaction between ADAM22 and 14-3-3 proteins is dependent on phosphorylation of ADAM22, but not of 14-3-3 proteins. ADAM22 point mutants lacking functional 14-3-3 protein binding motifs could no longer accumulate efficiently at the cell surface. Deletion of both 14-3-3 binding sites and newly identified ER retention motifs restored localization of ADAM22 at the cell surface. These results reveal a role for 14-3-3 proteins in targeting ADAM22 to the membrane by masking ER retention signals.

Inhibitors of alpha-synuclein oligomerization and toxicity: a future therapeutic strategy for Parkinson's disease and related disorders

An abundance of genetic, histopathological, and biochemical evidence has implicated the neuronal protein, alpha-synuclein (alpha-syn) as a key player in the development of several neurodegenerative diseases, the so-called synucleinopathies, of which Parkinson's disease (PD) is the most prevalent. Development of disease appears to be linked to events that increase the intracellular concentration of alpha-syn or cause its chemical modification, either of which can accelerate the rate at which it forms aggregates. Examples of such events include increased copy number of genes, decreased rate of degradation via the proteasome or other proteases, or altered forms of alpha-syn, such as truncations, missense mutations, or chemical modifications by oxidative reactions. Aggregated forms of the protein, especially newly formed soluble aggregates, are toxic to cells, so that one therapeutic strategy would be to reduce the rate at which such oligomerization occurs. We have therefore designed several peptides and also identified small molecules that can inhibit alpha-syn oligomerization and toxicity in vitro. These compounds could serve as lead compounds for the design of new drugs for the treatment of PD and related disorders in the future.