14-3-3 Proteins regulate Akt Thr308 phosphorylation in intestinal epithelial cells

14-3-3 Family of Proteins: Biological Implications, Molecular Interactions, and Potential Intervention in Cancer, Virus and Neurodegeneration Disorders

The 14-3-3 family of proteins are highly conserved acidic eukaryotic proteins (25-32 kDa) abundantly present in the body. Through numerous binding partners, the 14-3-3 is responsible for many essential cellular pathways, such as cell cycle regulation and gene transcription control. Hence, its dysregulation has been linked to the onset of critical illnesses such as cancers, neurodegenerative diseases and viral infections. Interestingly, explorative studies have revealed an inverse correlation of 14-3-3 protein in cancer and neurodegenerative diseases, and the direct manipulation of 14-3-3 by virus to enhance infection capacity has dramatically extended its significance. Of these, COVID-19 has been linked to the 14-3-3 proteins by the interference of the SARS-CoV-2 nucleocapsid (N) protein during virion assembly. Given its predisposition towards multiple essential host signalling pathways, it is vital to understand the holistic interactions between the 14-3-3 protein to unravel its potential therapeutic unit in the future. As such, the general structure and properties of the 14-3-3 family of proteins, as well as their known biological functions and implications in cancer, neurodegeneration, and viruses, were covered in this review. Furthermore, the potential therapeutic target of 14-3-3 proteins in the associated diseases was discussed.

Targeting PI3K/AKT/mTOR signaling to overcome drug resistance in cancer

This review comprehensively explores the challenge of drug resistance in cancer by focusing on the pivotal PI3K/AKT/mTOR pathway, elucidating its role in oncogenesis and resistance mechanisms across various cancer types. It meticulously examines the diverse mechanisms underlying resistance, including genetic mutations, feedback loops, and microenvironmental factors, while also discussing the associated resistance patterns. Evaluating current therapeutic strategies targeting this pathway, the article highlights the hurdles encountered in drug development and clinical trials. Innovative approaches to overcome resistance, such as combination therapies and precision medicine, are critically analyzed, alongside discussions on emerging therapies like immunotherapy and molecularly targeted agents. Overall, this comprehensive review not only sheds light on the complexities of resistance in cancer but also provides a roadmap for advancing cancer treatment.

Kinesin Regulation in the Proximal Axon is Essential for Dendrite-selective Transport

Neurons are polarized and typically extend multiple dendrites and one axon. To maintain polarity, vesicles carrying dendritic proteins are arrested upon entering the axon. To determine whether kinesin regulation is required for terminating anterograde axonal transport, we overexpressed the dendrite-selective kinesin KIF13A. This caused mistargeting of dendrite-selective vesicles to the axon and a loss of dendritic polarity. Polarity was not disrupted if the kinase MARK2/Par1b was coexpressed. MARK2/Par1b is concentrated in the proximal axon, where it maintains dendritic polarity-likely by phosphorylating S1371 of KIF13A, which lies in a canonical 14-3-3 binding motif. We probed for interactions of KIF13A with 14-3-3 isoforms and found that 14-3-3β and 14-3-3ζ bound KIF13A. Disruption of MARK2 or 14-3-3 activity by small molecule inhibitors caused a loss of dendritic polarity. These data show that kinesin regulation is integral for dendrite-selective transport. We propose a new model in which KIF13A that moves dendrite-selective vesicles in the proximal axon is phosphorylated by MARK2. Phosphorylated KIF13A is then recognized by 14-3-3, which causes dissociation of KIF13A from the vesicle and termination of transport. These findings define a new paradigm for the regulation of vesicle transport by localized kinesin tail phosphorylation, to restrict dendrite-selective vesicles from entering the axon.

Jnk1 and downstream signalling hubs regulate anxiety-like behaviours in a zebrafish larvae phenotypic screen

Current treatments for anxiety and depression show limited efficacy in many patients, indicating the need for further research into the underlying mechanisms. JNK1 has been shown to regulate anxiety- and depressive-like behaviours in mice, however the effectors downstream of JNK1 are not known. Here we compare the phosphoproteomes from wild-type and Jnk1-/- mouse brains and identify JNK1-regulated signalling hubs. We next employ a zebrafish (Danio rerio) larvae behavioural assay to identify an antidepressant- and anxiolytic-like (AA) phenotype based on 2759 measured stereotypic responses to clinically proven antidepressant and anxiolytic (AA) drugs. Employing machine learning, we classify an AA phenotype from extracted features measured during and after a startle battery in fish exposed to AA drugs. Using this classifier, we demonstrate that structurally independent JNK inhibitors replicate the AA phenotype with high accuracy, consistent with findings in mice. Furthermore, pharmacological targeting of JNK1-regulated signalling hubs identifies AKT, GSK-3, 14-3-3 ζ/ε and PKCε as downstream hubs that phenocopy clinically proven AA drugs. This study identifies AKT and related signalling molecules as mediators of JNK1-regulated antidepressant- and anxiolytic-like behaviours. Moreover, the assay shows promise for early phase screening of compounds with anti-stress-axis properties and for mode of action analysis.

METTL14 promotes neuroblastoma formation by inhibiting YWHAH via an m6A-YTHDF1-dependent mechanism

Neuroblastoma (NB) is a common childhood tumor with a high incidence worldwide. The regulatory role of RNA N6-methyladenosine (m6A) in gene expression has attracted significant attention, and the impact of methyltransferase-like 14 (METTL14) on tumor progression has been extensively studied in various types of cancer. However, the specific influence of METTL14 on NB remains unexplored. Using data from the Target database, our study revealed significant upregulation of METTL14 expression in high-risk NB patients, with strong correlation with poor prognosis. Furthermore, we identified ETS1 and YY1 as upstream regulators that control the expression of METTL14. In vitro experiments involving the knockdown of METTL14 in NB cells demonstrated significant inhibition of cell proliferation, migration, and invasion. In addition, suppressing METTL14 inhibited NB tumorigenesis in nude mouse models. Through MeRIP-seq and RNA-seq analyses, we further discovered that YWHAH is a downstream target gene of METTL14. Mechanistically, we observed that methylated YWHAH transcripts, particularly those in the 5' UTR, were specifically recognized by the m6A "reader" protein YTHDF1, leading to the degradation of YWHAH mRNA. Moreover, the downregulation of YWHAH expression activated the PI3K/AKT signaling pathway, promoting NB cell activity. Overall, our study provides valuable insights into the oncogenic effects of METTL14 in NB cells, highlighting its role in inhibiting YWHAH expression through an m6A-YTHDF1-dependent mechanism. These findings also suggest the potential utility of a biomarker panel for prognostic prediction in NB patients.

Usnic Acid Targets 14-3-3 Proteins and Suppresses Cancer Progression by Blocking Substrate Interaction

The anticancer therapeutic effects of usnic acid (UA), a lichen secondary metabolite, have been demonstrated in vitro and in vivo. However, the mechanism underlying the anticancer effect of UA remains to be clarified. In this study, the target protein of UA was identified using a UA-linker-Affi-Gel molecule, which showed that UA binds to the 14-3-3 protein. UA binds to 14-3-3, causing the degradation of proteasomal and autophagosomal proteins. The interaction of UA with 14-3-3 isoforms modulated cell invasion, cell cycle progression, aerobic glycolysis, mitochondrial biogenesis, and the Akt/mTOR, JNK, STAT3, NF-κB, and AP-1 signaling pathways in colorectal cancer. A peptide inhibitor of 14-3-3 blocked or regressed the activity of UA and inhibited its effects. The results suggest that UA binds to 14-3-3 isoforms and suppresses cancer progression by affecting 14-3-3 targets and phosphorylated proteins.

Promotion of 14-3-3ζ/Heme Oxygenase-1 Axis on Endotoxin-Induced Uveitis and Microglia Ferroptosis in Mice

PURPOSE

Uveitis is a common, sight-threatening inflammatory ocular disease and is the main cause of blindness, which is caused by autoimmune response, infection, and injury. The contribution of 14-3-3ζ in uveitis remains obscure. This study aims to investigate the role of 14-3-3ζ in regulating ferroptosis in retinal inflammation and its contribution to uveitis.

METHODS

A lipopolysaccharide (LPS)-induced uveitis mouse model and BV-2 cell line were used to examine the effect of LPS stimulation on the expression of 14-3-3ζ and ferroptosis in microglia. The expression of heme oxygenase-1 (HO-1) was also analyzed to understand its role in promoting microglial ferroptosis.

RESULTS

We found that LPS stimulation increased the expression of 14-3-3ζ and promoted ferroptosis in microglia. Additionally, 14-3-3ζ was found to promote microglial ferroptosis by stabilizing the expression of HO-1. These findings suggest that the 14-3-3ζ/HO-1 axis plays a crucial role in promoting microglial ferroptosis in retinal inflammation.

CONCLUSION

The study provides valuable insights into the mechanisms underlying uveitis and highlights the potential of the 14-3-3ζ/HO-1 axis as a therapeutic target for the disease. Further research in this area could lead to the development of preventive and therapeutic strategies for uveitis.

Brucella targets the host ubiquitin-specific protease, Usp8, through the effector protein, TcpB, for facilitating infection of macrophages

Brucella species are Gram-negative intracellular bacterial pathogens that cause the worldwide zoonotic disease brucellosis. Brucella can infect many mammals, including humans and domestic and wild animals. Brucella manipulates various host cellular processes to invade and multiply in professional and non-professional phagocytic cells. However, the host targets and their modulation by Brucella to facilitate the infection process remain obscure. Here, we report that the host ubiquitin-specific protease, USP8, negatively regulates the invasion of Brucella into macrophages through the plasma membrane receptor, CXCR4. Upon silencing or chemical inhibition of USP8, the membrane localization of the CXCR4 receptor was enriched, which augmented the invasion of Brucella into macrophages. Activation of USP8 through chemical inhibition of 14-3-3 protein affected the invasion of Brucella into macrophages. Brucella suppressed the expression of Usp8 at its early stage of infection in the infected macrophages. Furthermore, we found that only live Brucella could negatively regulate the expression of Usp8, suggesting the role of secreted effector protein of Brucella in modulating the gene expression. Subsequent studies revealed that the Brucella effector protein, TIR-domain containing protein from Brucella, TcpB, plays a significant role in downregulating the expression of Usp8 by targeting the cyclic-AMP response element-binding protein pathway. Treatment of mice with USP8 inhibitor resulted in enhanced survival of B. melitensis, whereas mice treated with CXCR4 or 14-3-3 antagonists showed a diminished bacterial load. Our experimental data demonstrate a novel role of Usp8 in the host defense against microbial intrusion. The present study provides insights into the microbial subversion of host defenses, and this information may ultimately help to develop novel therapeutic interventions for infectious diseases.

The effect of Par3 on the cellular junctions and biological functions of odontoblast-lineage cells

Perfect intercellular junctions are key for odontoblast barrier function. However, whether Partitioning defective-3 (Par3) is expressed in odontoblasts and its potential effects on odontoblast junctions are unknown. Herein, we investigated the effect of Par3 on cellular junctions and the biological behavior of odontoblast-lineage cells (OLCs). Whole-transcriptome sequencing was used to analyze the effects of Par3 on OLCs and the underlying molecular mechanism. Par3 was detected under physiological and inflammatory conditions in OLCs. To investigate the regulatory effect of Par3 on junctions between mouse OLCs, the effects of Par3 downregulation on the proliferation, migration, cycle and apoptosis of OLCs were detected by 5-ethyl-2'-deoxyuridine (EdU) and Transwell assays and flow cytometry. Western blotting and alizarin red S and alkaline phosphatase (ALP) staining were used to observe the effect of Par3 downregulation on OLC mineralization. Whole-transcriptome sequencing was used to investigate the biological role of Par3 in OLCs and potential molecular mechanisms. Par3 was located along the odontoblast layer in the rat pulp tissue and in the cytoplasm of OLCs. Par3 expression was downregulated under inflammatory conditions. The OLC junctions were discontinuous, and total Zona occluden-1 (ZO-1) expression and expression of ZO-1 at the membrane in OLCs were reduced after Par3 silencing (P < 0.05). Expression of a junction-related protein (ZO-1) was downregulated after the downregulation of Par3 (P < 0.05), and ZO-1 moved from the cell membrane to the cytoplasm. OLC proliferation and migration were enhanced, but apoptosis and mineralization were inhibited in shPar3-transfected cells (P < 0.05). Sequencing identified 2996 differentially expressed genes (DEGs), which were mainly enriched in the response to stimuli and binding. Downregulation of Par3 could overactivate the PI3k-AKT pathway by promoting AKT phosphorylation (P < 0.05). Downregulation of Par3 may disrupt junctions between OLCs by affecting ZO-1 expression and distribution and promote OLC proliferation and migration but inhibit OLC mineralization. Par3 may interact with 14-3-3 proteins for PI3K-AKT pathway activation to affect OLC junctions and function.

Mirabegron alleviates acetic acid-induced colitis in rats: role of adiponectin and GSTM1/GSH detoxification pathway

The prevalence of the debilitating chronic disease ulcerative colitis (UC) is increasing significantly. Mirabegron is a selective beta-3 adrenergic receptor (β-3 AR) agonist used to treat an overactive bladder. Previous reports have demonstrated the antidiarrheal effect of β-3AR agonists. Therefore, the current study aims to investigate the potential symptomatic effects of mirabegron on an experimental colitis model. The effects of oral administration of mirabegron (10mg/kg) for seven days on rats receiving intra-rectal acetic acid instillation on the sixth day were examined using adult male Wistar rats. Sulfasalazine was utilized as a reference medication. Gross, microscopic, and biochemical observations of the experimental colitis were performed. The quantity and mucin content of goblet cells were found to have significantly decreased in the colitis group. In the colons of rats administered mirabegron, the number of goblet cells and the optical density of its mucin content increased. Mirabegron's ability to increase adiponectin in serum and decrease glutathione, GSTM1, and catalase in the colon may account for its protective effects. In addition, mirabegron decreased the expression of the proteins caspase-3 and NF-κB p65. It also prevented the activation of their upstream signaling receptors TLR4 and p-AKT by acetic acid administration. In conclusion, mirabegron prevented acetic acid-induced colitis in rats, possibly due to its antioxidant, anti-inflammatory, and antiapoptotic properties.

Stabilization of 14-3-3 protein-protein interactions with Fusicoccin-A decreases alpha-synuclein dependent cell-autonomous death in neuronal and mouse models

Synucleinopathies are a group of neurodegenerative diseases without effective treatment characterized by the abnormal aggregation of alpha-synuclein (aSyn) protein. Changes in levels or in the amino acid sequence of aSyn (by duplication/triplication of the aSyn gene or point mutations in the encoding region) cause familial cases of synucleinopathies. However, the specific molecular mechanisms of aSyn-dependent toxicity remain unclear. Increased aSyn protein levels or pathological mutations may favor abnormal protein-protein interactions (PPIs) that could either promote neuronal death or belong to a coping response program against neurotoxicity. Therefore, the identification and modulation of aSyn-dependent PPIs can provide new therapeutic targets for these diseases. To identify aSyn-dependent PPIs we performed a proximity biotinylation assay based on the promiscuous biotinylase BioID2. When expressed as a fusion protein, BioID2 biotinylates by proximity stable and transient interacting partners, allowing their identification by streptavidin affinity purification and mass spectrometry. The aSyn interactome was analyzed using BioID2-tagged wild-type (WT) and pathological mutant E46K aSyn versions in HEK293 cells. We found the 14-3-3 epsilon isoform as a common protein interactor for WT and E46K aSyn. 14-3-3 epsilon correlates with aSyn protein levels in brain regions of a transgenic mouse model overexpressing WT human aSyn. Using a neuronal model in which aSyn cell-autonomous toxicity is quantitatively scored by longitudinal survival analysis, we found that stabilization of 14-3-3 protein-proteins interactions with Fusicoccin-A (FC-A) decreases aSyn-dependent toxicity. Furthermore, FC-A treatment protects dopaminergic neuronal somas in the substantia nigra of a Parkinson's disease mouse model. Based on these results, we propose that the stabilization of 14-3-3 epsilon interaction with aSyn might reduce aSyn toxicity, and highlight FC-A as a potential therapeutic compound for synucleinopathies.

Missense and nonsense mutations of the zebrafish hcfc1a gene result in contrasting mTor and radial glial phenotypes

Mutations in the HCFC1 transcriptional co-factor protein are the cause of cblX syndrome and X-linked intellectual disability (XLID). cblX is the more severe disorder associated with intractable epilepsy, abnormal cobalamin metabolism, facial dysmorphia, cortical gyral malformations, and intellectual disability. In vitro, murine Hcfc1 regulates neural precursor (NPCs) proliferation and number, which has been validated in zebrafish. However, conditional deletion of mouse Hcfc1 in Nkx2.1 + cells increased cell death, reduced Gfap expression, and reduced numbers of GABAergic neurons. Thus, the role of this gene in brain development is not completely understood. Recently, knock-in of both a cblX (HCFC1) and cblX-like (THAP11) allele were created in mice. Knock-in of the cblX-like allele was associated with increased expression of proteins required for ribosome biogenesis. However, the brain phenotypes were not comprehensively studied due to sub-viability. Therefore, a mechanism underlying increased ribosome biogenesis was not described. We used a missense, a nonsense, and two conditional zebrafish alleles to further elucidate this mechanism during brain development. We observed contrasting phenotypes at the level of Akt/mTor activation, the number of radial glial cells, and the expression of two downstream target genes of HCFC1, asxl1 and ywhab. Despite these divergent phenotypes, each allele studied demonstrates with a high degree of face validity when compared to the phenotypes reported in the literature. Collectively, these data suggest that individual mutations in the HCFC1 protein result in differential mTOR activity which may be associated with contrasting cellular phenotypes.

The role of 14-3-3 in the progression of vascular inflammation induced by lipopolysaccharide

OBJECTIVE

To explore the role of 14-3-3 protein and the Hippo and yes-associated protein 1 (YAP) signaling pathway in lipopolysaccharide (LPS)-induced vascular inflammation.

METHODS

Human umbilical vein endothelial cells (HUVECs) and C57B6 mice were treated with LPS to establish cell and animal models of vascular inflammation. Lentiviral transfection, Western blot, qPCR, immunofluorescence, immunohistochemistry, co-immunoprecipitation, and enzyme-linked immunosorbent assays were used to measure inflammatory factors and expression of 14-3-3 protein and phosphorylation of YAP at S127. HUVECs and C57B6 mice were pretreated with a YAP inhibitor, Verteporfin, to observe changes in YAP expression and downstream vascular inflammation.

RESULTS

LPS induced acute and chronic inflammatory responses in HUVECs and mice and upregulated the expression of several inflammatory factors. LPS also induced expression of 14-3-3 protein and phosphorylation of YAP at S127 in response to acute vascular inflammation and downregulated these markers in response to chronic vascular inflammation. Verteporfin reduced these LPS-induced effects on vascular inflammation.

CONCLUSION

In chronic vascular inflammation, 14-3-3 protein is downregulated, which promotes inflammation by increasing Hippo/YAP nuclear translocation.

Sinomenine attenuated dextran sulfate sodium-induced inflammatory responses by promoting 14-3-3θ protein and inhibiting NF-κB signaling

ETHNOPHARMACOLOGICAL RELEVANCE

The rhizome of Chinese medical plant QingTeng (scientific name: Sinomenium acutum (Thunb.) Rehd. et Wils.) is widely used by traditional medical doctors for anti-inflammation and immunoregulatory in China and other Asian countries.

AIM OF THE STUDY

The purpose of this study was to evaluate the effects and possible mechanisms of sinomenine resistance against DSS-induced inflammation in vitro and in vivo.

MATERIALS AND METHODS

The UC model was induced by treating female mice with 3% DSS in vivo and human colonic epithelial cells (Hcoepic) with 0.8 mg/ml DSS in vitro. The mice and Hcoepic were then treated with sinomenine. Inflammatory factors were detected using ELISA and qRT-PCR. Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) p65 and 14-3-3θ were analyzed by bioinformatic analysis and verified by western blotting, immunofluorescent staining or immunohistochemistry.

RESULTS

DSS-induced Hcoepic underwent high inflammation and oxidative stress conditions, whereas sinomenine reduced the uncontrolled immune microenvironment by suppressing NF-κB signaling and targeting 14-3-3θ. Knockdown of 14-3-3θ decreased the protective effect of sinomenine against DSS-induced inflammation in vitro. Moreover, sinomenine promoted 14-3-3θ protein expression and inhibited NF-κB p65 signaling in DSS-induced mice.

CONCLUSION

These findings suggest that 14-3-3θ plays an important role in sinomenine against DSS treatment, and sinomenine could be considered a potential drug for the treatment of UC.

High-Resolution Crystal Structure of Muscle Phosphoglycerate Mutase Provides Insight into Its Nuclear Import and Role

Phosphoglycerate mutase (PGAM) is a glycolytic enzyme converting 3-phosphoglycerate to 2-phosphoglycerate, which in mammalian cells is expressed in two isoforms: brain (PGAM1) and muscle (PGAM2). Recently, it was shown that besides its enzymatic function, PGAM2 can be imported to the cell nucleus where it co-localizes with the nucleoli. It was suggested that it functions there to stabilize the nucleolar structure, maintain mRNA expression, and assist in the assembly of new pre-ribosomal subunits. However, the precise mechanism by which the protein translocates to the nucleus is unknown. In this study, we present the first crystal structure of PGAM2, identify the residues involved in the nuclear localization of the protein and propose that PGAM contains a “quaternary nuclear localization sequence (NLS)”, i.e., one that consists of residues from different protein chains. Additionally, we identify potential interaction partners for PGAM2 in the nucleoli and demonstrate that 14-3-3ζ/δ is indeed an interaction partner of PGAM2 in the nucleus. We also present evidence that the insulin/IGF1–PI3K–Akt–mTOR signaling pathway is responsible for the nuclear localization of PGAM2.

14-3-3τ drives estrogen receptor loss via ERα36 induction and GATA3 inhibition in breast cancer

About one-fourth of recurrent estrogen receptor-positive (ER+) breast cancers lose ER expression, leading to endocrine therapy failure. However, the mechanisms underlying ER loss remain to be fully explored. We now show that 14-3-3τ, up-regulated in ∼60% of breast cancer, drives the conversion of ER+ to ER- and epithelial-to-mesenchymal transition (EMT). We identify ERα36, an isoform of ERα66, as a downstream effector of 14-3-3τ. Overexpression of 14-3-3τ induces ERα36 in xenografts and tumor spheroids. The regulation is further supported by a positive correlation between ERα36 and 14-3-3τ expression in human breast cancers. ERα36 can antagonize ERα66 and inhibit ERα66 expression. Isoform-specific depletion of ERα36 blocks the ER conversion and EMT induced by 14-3-3τ overexpression in tumor spheroids, thus establishing ERα36 as a key mediator in 14-3-3τ-driven ER loss and EMT. ERα36 promoter is repressed by GATA3, which can be phosphorylated by AKT at consensus binding sites for 14-3-3. Upon AKT activation, 14-3-3τ binds phosphorylated GATA3 and facilitates the degradation of GATA3 causing GATA3 to lose transcriptional control over its target genes ERα66 and ERα36. We also demonstrate a role for the collaboration between 14-3-3τ and AKT in ERα36 induction and endocrine therapy resistance by three-dimensional spheroid and tamoxifen treatment models in MCF7 and T47D ER+ breast cancer cells. Thus, the 14-3-3τ-ERα36 regulation provides a previously unrecognized mechanism for ER loss and endocrine therapy failure.

Reducing PDK1/Akt Activity: An Effective Therapeutic Target in the Treatment of Alzheimer's Disease

Alzheimer’s disease (AD) is a common age-related neurodegenerative disease that leads to memory loss and cognitive function damage due to intracerebral neurofibrillary tangles (NFTs) and amyloid-β (Aβ) protein deposition. The phosphoinositide-dependent protein kinase (PDK1)/protein kinase B (Akt) signaling pathway plays a significant role in neuronal differentiation, synaptic plasticity, neuronal survival, and neurotransmission via the axon–dendrite axis. The phosphorylation of PDK1 and Akt rises in the brain, resulting in phosphorylation of the TNF-α-converting enzyme (TACE) at its cytoplasmic tail (the C-terminal end), changing its internalization as well as its trafficking. The current review aimed to explain the mechanisms of the PDK1/Akt/TACE signaling axis that exerts its modulatory effect on AD physiopathology. We provide an overview of the neuropathological features, genetics, Aβ aggregation, Tau protein hyperphosphorylation, neuroinflammation, and aging in the AD brain. Additionally, we summarized the phosphoinositide 3-kinase (PI3K)/PDK1/Akt pathway-related features and its molecular mechanism that is dependent on TACE in the pathogenesis of AD. This study reviewed the relationship between the PDK1/Akt signaling pathway and AD, and discussed the role of PDK1/Akt in resisting neuronal toxicity by suppressing TACE expression in the cell membrane. This work also provides a perspective for developing new therapeutics targeting PDK1/Akt and TACE for the treatment of AD.

Extracellular vesicles of Lacticaseibacillus paracasei PC-H1 induce colorectal cancer cells apoptosis via PDK1/AKT/Bcl-2 signaling pathway

Colorectal cancer (CRC) is the third most common malignant tumor in the world. Previous research has shown that Lacticaseibacillus paracasei strains and its cultures have anti-colon cancer effects, but the study of L. paracasei-derived extracellular vesicles (LpEVs) as intercellular communication molecule against colon cancer has not been previously reported. Our research showed LpEVs were taken in by colorectal cancer cells. Subsequently, LpEVs inhibited the proliferation, migration, invasion and promote apoptosis of colorectal cancer cells. LpEVs inhibited the growth of CRC xenograft in nude mice and promoted tumor apoptosis in vivo. Transcriptome sequencing analysis revealed that differentially expressed genes were involved in the regulation of apoptosis. LpEVs significantly inhibited the phosphorylation level of 3-phosphoinositide-dependent protein kinase-1 (PDK1) and AKT in colorectal cancer cells and reduced the expression of Bcl-2 protein. In conclusion, extracellular vesicles of Lacticaseibacillus paracasei PC-H1 can inhibit the growth of colorectal cancer cells in vivo and vitro and induce apoptosis through PDK1/AKT/Bcl-2 signaling pathway. This research not only provides a new mechanism for the anti-tumor effects of probiotics, but also opens up new opportunity for the treatment of colon cancer.

Serum Anti-14-3-3 Zeta Autoantibody as a Biomarker for Predicting Hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is a common malignancy worldwide. Alpha-fetoprotein (AFP) is still the only serum biomarker widely used in clinical settings. However, approximately 40% of HCC patients exhibit normal AFP levels, including very early HCC and AFP-negative HCC; for these patients, serum AFP is not applicable as a biomarker of early detection. Thus, there is an urgent need to identify novel biomarkers for patients for whom disease cannot be diagnosed early. In this study, we screened and identified novel proteins in AFP-negative HCC and evaluated the feasibility of using autoantibodies to those protein to predict hepatocarcinogenesis. First, we screened and identified differentially expressed proteins between AFP-negative HCC tissue and adjacent non-tumor liver tissue using SWATH-MS proteome technology. In total, 2,506 proteins were identified with a global false discovery rate of 1%, of which 592 proteins were expressed differentially with 175 upregulated and 417 downregulated (adjusted p-value <0.05, fold-change FC ≥1.5 or ≤0.67) between the tumor and matched benign samples, including 14-3-3 zeta protein. For further serological verification, autoantibodies against 14-3-3 zeta in serum were evaluated using enzyme-linked immunosorbent, Western blotting, and indirect immunofluorescence assays. Five serial serum samples from one patient with AFP-negative HCC showed anti-14-3-3 zeta autoantibody in sera 9 months before the diagnosis of HCC, which gradually increased with an increase in the size of the nodule. Based on these findings, we detected the prevalence of serum anti-14-3-3 zeta autoantibody in liver cirrhosis (LC) patients, which is commonly considered a premalignant liver disease of HCC. We found that the prevalence of autoantibodies against 14-3-3 zeta protein was 16.1% (15/93) in LC patient sera, which was significantly higher than that in patients with chronic hepatitis (0/75, p = 0.000) and normal human sera (1/60, 1.7%, p = 0.01). Therefore, we suggest that anti-14-3-3 zeta autoantibody might be a biomarker for predicting hepatocarcinogenesis. Further follow-up and research of patients with positive autoantibodies will be continued to confirm the relationship between anti-14-3-3 zeta autoantibody and hepatocarcinogenesis.

FSCN1 Promotes Radiation Resistance in Patients With PIK3CA Gene Alteration

Radiotherapy is one of the standard treatments for cervical cancer and head and neck cancer. However, the clinical efficacy of this treatment is limited by radioresistance. The discovery of effective prognostic biomarkers and the identification of new therapeutic targets have helped to overcome the problem of radioresistance. In this study, we show that in the context of PIK3CA mutation or amplification, high expression of fascin actin-bundling protein 1 (FSCN1) (using the median as the cut-off value) is associated with poor prognosis and radiotherapy response in cancer patients. Silencing FSCN1 enhances radiosensitivity and promotes apoptosis in cancer cells with PIK3CA alterations, and this process may be associated with the downregulation of YWHAZ. These results reveal that FSCN1 may be a key regulator of radioresistance and could be a potential target for improving radiotherapy efficacy in cervical cancer and head and neck cancer patients with PIK3CA alterations.

Rictor/Mammalian Target of Rapamycin Complex 2 Signaling Protects Colonocytes from Apoptosis and Prevents Epithelial Barrier Breakdown

Epithelial barrier impairment is a hallmark of several pathologic processes in the gut, including inflammatory bowel diseases. Several intracellular signals prevent apoptosis in intestinal epithelial cells. Herein, we show that in colonocytes, rictor/mammalian target of rapamycin complex 2 (mTORC2) signaling is a prosurvival stimulus. Mechanistically, mTORC2 activates Akt, which, in turn, inhibits apoptosis by phosphorylating B-cell lymphoma 2 (BCL2) associated agonist of cell death (Bad) and preventing caspase-3 activation. Nevertheless, during inflammation, rictor/mTORC2 signaling declines and Akt activity is reduced. Consequently, active caspase-3 increases in surface colonocytes undergoing apoptosis/anoikis and causes epithelial barrier breakdown. Likewise, Rictor ablation in intestinal epithelial cells interrupts mTORC2/Akt signaling and increases apoptosis/anoikis of surface colonocytes without affecting the crypt architecture. The increase in epithelial permeability induced by Rictor ablation produces a mild inflammatory response in the colonic mucosa, but minimally affects the development/establishment of colitis. The data identify a previously unknown mechanism by which rictor/mTORC2 signaling regulates apoptosis/anoikis in intestinal epithelial cells during colitis and clarify its role in the maintenance of the intestinal epithelial barrier.

Posttranslational modifications as therapeutic targets for intestinal disorders

A variety of biological processes are regulated by posttranslational modifications. Posttranslational modifications including phosphorylation, ubiquitination, glycosylation, and proteolytic cleavage, control diverse physiological functions in the gastrointestinal tract. Therefore, a better understanding of their implications in intestinal diseases, including inflammatory bowel disease, irritable bowel syndrome, celiac disease, and colorectal cancer would provide a basis for the identification of novel biomarkers as well as attractive therapeutic targets. Posttranslational modifications can be common denominators, as well as distinct biomarkers, characterizing pathological differences of various intestinal diseases. This review provides experimental evidence that identifies changes in posttranslational modifications from patient samples, primary cells, or cell lines in intestinal disorders, and a summary of carefully selected information on the use of pharmacological modulators of protein modifications as therapeutic options.

Significant reductions in apoptosis-related proteins (HSPA6, HSPA8, ITGB3, YWHAH, and PRDX6) are involved in immune thrombocytopenia

To investigate differences in the expression of plasma proteins in immune thrombocytopenia (ITP) and normal control groups, bone marrow samples were collected from 20 active ITP patients and 20 healthy controls. Quantitative proteomics analysis based on mass spectrometry was used to measure the protein levels and understand the protein networks. We found differentially expressed proteins in ITP patients and healthy controls. Parallel reaction monitoring (PRM), a targeted proteome quantification technique, was used to quantitatively confirm the identified target proteins and verify the proteomics data. In this study, a total of 829 proteins were identified, and the fold-change cut-off was set at 1.5 (patients vs controls); a total of 26 proteins were upregulated, and 69 proteins were downregulated. The bioinformatics analysis indicated that some differentially expressed proteins were associated with apoptosis. KEGG enrichment analysis showed that the apoptosis-related proteins were closely related to the PI3K-Akt signalling pathway. PRM demonstrated that apoptosis-related proteins were significantly decreased in ITP patients, which further confirmed the important effect of apoptosis on ITP pathogenesis. We hypothesised that apoptosis may be closely related to ITP pathogenesis through the PI3K-Akt signalling pathway.

Integrating proteomics into precision oncology

DNA sequencing and RNA sequencing are increasingly applied in precision oncology, where molecular tumor boards evaluate the actionability of genetic events in individual tumors to guide targeted treatment. To work toward an additional level of patient characterization, we assessed the abundance and activity of 27 proteins in 134 patients whose tumors had previously undergone whole-exome and RNA sequencing within the Molecularly Aided Stratification for Tumor Eradication Research (MASTER) program of National Center for Tumor Diseases, Heidelberg. Proteomic and phosphoproteomic targets were selected to reflect the most relevant therapeutic baskets in MASTER. Among six different therapeutic baskets, the proteomic data supported treatment recommendations that were based on DNA and RNA analyses in 10% to 57% and frequently suggested alternative treatment options. In several cases, protein activities explained the patients' clinical course and provided potential explanations for treatment failure. Our study indicates that the integrative analysis of DNA, RNA and protein data may refine therapeutic stratification of individual patients and, thus, holds potential to increase the success rate of precision cancer therapy. Prospective validation studies are needed to advance the integration of proteomic analysis into precision oncology.

Metabotropic signaling cascade involved in α4β2 nicotinic acetylcholine receptor-mediated PKCβII activation

Nicotinic acetylcholine receptors (nAChRs) belong to the ionophore receptor family, which regulates plasma membrane conductance to Na⁺, K⁺, and Ca²⁺ ions. Some studies, however, have shown that nAChRs also employ second messengers for intracellular signaling. We previously showed that α4β2 nAChR mediates the translocation of protein kinase CβII (PKCβII) from the cytoplasm to the plasma membrane, which is a typical activation marker for PKCβII. In this study, we investigated the molecular mechanisms underlying PKCβII activation through α4β2 nAChR. α4β2 nAChR is the most abundant nAChR subtype and is implicated in various brain functions and diseases. Putative α4β2 nAChR signaling components were identified by knockdown or chemical inhibition of candidate proteins, and the signaling cascade was deduced by protein interactions in predicted cellular components. α4β2 nAChR-mediated PKCβII translocation was found to occur in an ionophore activity-independent manner. Nicotinic stimulation of α4β2 nAChR activated Src in a β-arrestin1 and 14-3-3η-dependent manner. Activated Src phosphorylated the tyrosine residue(s) on Syk molecules, which in turn interacted with phospholipase C γ1 to trigger the translocation of PKCβII to the cell membrane by elevating cellular diacylglycerol levels. The activated PKCβII in turn exerted a positive feedback effect on Src activation, suggesting that α4β2 nAChR signaling is amplified by a positive feedback loop. These findings provide novel information for unveiling the previously unclear metabotropic second messenger-based signal transduction pathway of nAChRs.

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.

Metabolic syndrome diminishes insulin-induced Akt activation and causes a redistribution of Akt-interacting proteins in cardiomyocytes

Metabolic syndrome (MetS) is a cluster of cardiometabolic risk factors, with insulin resistance as a critical component for its development. Insulin signaling in the heart leads to Akt (also known as PKB) activation, a serine/threonine protein kinase, which regulates cardiac glucose metabolism and growth. Cardiac metabolic inflexibility, characterized by impaired insulin-induced glucose uptake and oxidation, has been reported as an early and consistent change in the heart of different models of MetS and diabetes; however, the evaluation of Akt activation has yielded variable results. Here we report in cardiomyocytes of MetS rats, diminished insulin-induced glucose uptake and Akt activation, evaluated by its impaired mobilization towards the plasma membrane and phosphorylation, and reflected in a re-distribution of its interacting proteins, assessed by label-free mass spectrometry (data are available via ProteomeXchange with identifier PXD013260). We report 45 proteins with diminished abundance in Akt complex of MetS cardiomyocytes, mainly represented by energy metabolism-related proteins, and also, 31 Akt-interacting proteins with increased abundance, which were mainly related to contraction, endoplasmic reticulum stress, and Akt negative regulation. These results emphasize the relevance of Akt in the regulation of energy metabolism in the heart and highlight Akt-interacting proteins that could be involved in the detrimental effects of MetS in the heart.

Glucocorticoids and myosin5b loss of function induce heightened PKA signaling in addition to membrane traffic defects

Loss-of-function mutations in the nonconventional myosin Vb (Myo5b) result in microvillus inclusion disease (MVID) and massive secretory diarrhea that often begins at birth. Myo5b mutations disrupt the apical recycling endosome (ARE) and membrane traffic, resulting in reduced surface expression of apical membrane proteins. ARE disruption also results in constitutive phosphoinositide-dependent kinase 1 gain of function. In MVID, decreased surface expression of apical anion channels involved in Cl^- extrusion, such as cystic fibrosis transmembrane conductance regulator (CFTR), should reduce fluid secretion into the intestinal lumen. But the opposite phenotype is observed. To explain this contradiction and the onset of diarrhea, we hypothesized that signaling effects downstream from Myo5b loss of function synergize with higher levels of glucocorticoids to activate PKA and CFTR. Data from intestinal cell lines, human MVID, and Myo5b KO mouse intestine revealed changes in the subcellular redistribution of PKA activity to the apical pole, increased CFTR phosphorylation, and establishment of apical cAMP gradients in Myo5b-defective cells exposed to physiological levels of glucocorticoids. These cells also displayed net secretory fluid fluxes and transepithelial currents mainly from PKA-dependent Cl^- secretion. We conclude that Myo5b defects result in PKA stimulation that activates residual channels on the surface when intestinal epithelia are exposed to glucocorticoids at birth.

The protective effects of hydrogen sulfide on the myocardial ischemia via regulating Bmal1

BACKGROUND

To investigate the effect of hydrogen peroxide (H₂S) on myocardial clock gene Bmal1 in ischemic cardiomyocytes.

MATERIALS & METHODS

Quantitative PCR (qPCR) was used to detect the expression of Bmal1 at the mRNA level in H9C2 rat cardiomyocytes. The protein expressions of Bax and Bcl-2, PI3K/Akt, caspase-3 were measured by western blotting. The levels of reactive oxygen species (ROS) were determined by ELISA.

RESULTS

The expression level of clock gene Bmal1 demonstrated a clock rhythm of periodic oscillation within 24 h. Compared with the control group, H₂S treatment maintained the rhythm of the clock gene in ischemic cardiomyocytes and increased the transcription and expression levels of Bmal1. H₂S increased cell survival by activating PI3K/Akt signaling pathway, inhibiting mitochondrial apoptosis signaling, and reducing intracellular oxidative stress. PI3K/Akt and Bmal1 were demonstrated to be involved in H₂S protection of cardiomyocyte ischemia. Knockout of Bmal1 gene affects the degree of phosphorylation of Akt and Erk proteins, and the level of ROS production, resulting in a decrease in the protective effects of H₂S.

CONCLUSION

The expression level of Bmal1 has effects on the function of cardiomyocytes such as ROS production. The potential mechanism by which H₂S regulates clock genes may be related to the effect of clock genes on protein phosphorylation levels in ischemic cardiomyocytes.

Reversal of sorafenib resistance in hepatocellular carcinoma: epigenetically regulated disruption of 14-3-3η/hypoxia-inducible factor-1α

Sorafenib resistance is one of the main obstacles to the treatment of advanced/recurrent hepatocellular carcinoma (HCC). Here, sorafenib-resistant HCC cells and xenografts in nude mice were used as experimental models. A cohort of patients with advanced recurrent HCC who were receiving sorafenib therapy was used to assess the clinical significance of this therapy. Our data showed that 14-3-3η maintained sorafenib resistance in HCC. An analysis of the underlying molecular mechanisms revealed that 14-3-3η stabilizes hypoxia-inducible factor 1α (HIF-1α) through the inhibition of ubiquitin-dependent proteasome protein degradation, which leads to the maintenance of cancer stem cell (CSC) properties. We further found that microRNA-16 (miR-16) is a competent miRNA that reverses sorafenib resistance by targeting the 3'-UTR of 14-3-3η and thereby inhibits 14-3-3η/HIF-1α/CSC properties. In HCC patients, significant negative correlations were found between the expression of miR-16 and 14-3-3η, HIF-1α, or CSC properties. Further analysis showed that low miR-16 expression but high 14-3-3η expression can prognosticate sorafenib resistance and poor survival. Collectively, our present study indicated that miR-16/14-3-3η is involved in sorafenib resistance in HCC and that these two factors could be potential therapeutic targets and biomarkers for predicting the response to sorafenib treatment.

14-3-3 gene family in spotted sea bass (Lateolabrax maculatus): Genome-wide identification, phylogenetic analysis and expression profiles after salinity stress

The tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation (14-3-3) proteins are a group of highly conserved homologous and heterologous proteins involved in a wild range of physiological processes, including the regulation of many molecular phenomena under different environmental salinities. In this study, we identified eleven 14-3-3 genes from the spotted sea bass (Lateolabrax maculatus) genome and transcriptomic databases and verified their identities by conducting phylogenetic, syntenic and gene structure analyses. The spotted sea bass 14-3-3 genes are highly conserved based on sequence alignment, conserved domains and motifs, and tertiary structural feature. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis of 14-3-3 genes in gill of spotted sea bass under normal physiological conditions indicated that the expression level of 14-3-3 zeta was the highest among tested genes, followed by 14-3-3 theta. Furthermore, expression profiles of 14-3-3 genes in gill tissue (in vivo and in vitro) indicated that the 14-3-3 zeta and 14-3-3 theta genes were significantly induced by different environmental salinities in spotted sea bass, suggesting their potential involvement in response to salinity challenge. Our findings may lay the foundation for future functional studies on the 14-3-3 gene family in euryhaline teleosts.

Myosin 1F Regulates M1-Polarization by Stimulating Intercellular Adhesion in Macrophages

Intestinal macrophages are highly mobile cells with extraordinary plasticity and actively contribute to cytokine-mediated epithelial cell damage. The mechanisms triggering macrophage polarization into a proinflammatory phenotype are unknown. Here, we report that during inflammation macrophages enhance its intercellular adhesion properties in order to acquire a M1-phenotype. Using in vitro and in vivo models we demonstrate that intercellular adhesion is mediated by integrin-αVβ3 and relies in the presence of the unconventional class I myosin 1F (Myo1F). Intercellular adhesion mediated by αVβ3 stimulates M1-like phenotype in macrophages through hyperactivation of STAT1 and STAT3 downstream of ILK/Akt/mTOR signaling. Inhibition of integrin-αVβ3, Akt/mTOR, or lack of Myo1F attenuated the commitment of macrophages into a pro-inflammatory phenotype. In a model of colitis, Myo1F deficiency strongly reduces the secretion of proinflammatory cytokines, decreases epithelial damage, ameliorates disease activity, and enhances tissue repair. Together our findings uncover an unknown role for Myo1F as part of the machinery that regulates intercellular adhesion and polarization in macrophages.

mTORC1 Prevents Epithelial Damage During Inflammation and Inhibits Colitis-Associated Colorectal Cancer Development

Epithelial cells lining the intestinal mucosa constitute a selective-semipermeable barrier acting as first line of defense in the organism. The number of those cells remains constant during physiological conditions, but disruption of epithelial cell homeostasis has been observed in several pathologies. During colitis, epithelial cell proliferation decreases and cell death augments. The mechanism responsible for these changes remains unknown. Here, we show that the pro-inflammatory cytokine IFNγ contributes to the inhibition of epithelial cell proliferation in intestinal epithelial cells (IECs) by inducing the activation of mTORC1. Activation of mTORC1 in response to IFNγ was detected in IECs present along the crypt axis and in colonic macrophages. mTORC1 inhibition enhances cell proliferation, increases DNA damage in IEC. In macrophages, mTORC1 inhibition strongly reduces the expression of pro-inflammatory markers. As a consequence, mTORC1 inhibition exacerbated disease activity, increased mucosal damage, enhanced ulceration, augmented cell infiltration, decreased survival and stimulated tumor formation in a model of colorectal cancer CRC associated to colitis. Thus, our findings suggest that mTORC1 signaling downstream of IFNγ prevents epithelial DNA damage and cancer development during colitis.

Vimentin Diversity in Health and Disease

Vimentin is a protein that has been linked to a large variety of pathophysiological conditions, including cataracts, Crohn's disease, rheumatoid arthritis, HIV and cancer. Vimentin has also been shown to regulate a wide spectrum of basic cellular functions. In cells, vimentin assembles into a network of filaments that spans the cytoplasm. It can also be found in smaller, non-filamentous forms that can localise both within cells and within the extracellular microenvironment. The vimentin structure can be altered by subunit exchange, cleavage into different sizes, re-annealing, post-translational modifications and interacting proteins. Together with the observation that different domains of vimentin might have evolved under different selection pressures that defined distinct biological functions for different parts of the protein, the many diverse variants of vimentin might be the cause of its functional diversity. A number of review articles have focussed on the biology and medical aspects of intermediate filament proteins without particular commitment to vimentin, and other reviews have focussed on intermediate filaments in an in vitro context. In contrast, the present review focusses almost exclusively on vimentin, and covers both ex vivo and in vivo data from tissue culture and from living organisms, including a summary of the many phenotypes of vimentin knockout animals. Our aim is to provide a comprehensive overview of the current understanding of the many diverse aspects of vimentin, from biochemical, mechanical, cellular, systems biology and medical perspectives.

SRARP and HSPB7 are epigenetically regulated gene pairs that function as tumor suppressors and predict clinical outcome in malignancies

Deletions of chromosome 1p36 are common in cancers; however, despite extensive studies, there has been limited success for discovering candidate tumor suppressors in this region. SRARP has recently been identified as a novel corepressor of the androgen receptor (AR) and is located on chromosome 1p36. Here, bioinformatics analysis of large tumor datasets was performed to study SRARP and its gene pair, HSPB7. In addition, using cancer cell lines, mechanisms of SRARP and HSPB7 regulation and their molecular functions were investigated. This study demonstrated that SRARP and HSPB7 are a gene pair located 5.2 kb apart on 1p36.13 and are inactivated by deletions and epigenetic silencing in malignancies. Importantly, SRARP and HSPB7 have tumor suppressor functions in clonogenicity and cell viability associated with the downregulation of Akt and ERK. SRARP expression is inversely correlated with genes that promote cell proliferation and signal transduction, which supports its functions as a tumor suppressor. In addition, AR exerts dual regulatory effects on SRARP, and although an increased AR activity suppresses SRARP transcription, a minimum level of AR activity is required to maintain baseline SRARP expression in AR+ cancer cells. Furthermore, as observed with SRARP, HSPB7 interacts with the 14-3-3 protein, presenting a shared molecular feature between SRARP and HSPB7. Of note, genome- and epigenome-wide associations of SRARP and HSPB7 with survival strongly support their tumor suppressor functions. In particular, DNA hypermethylation, lower expression, somatic mutations, and lower copy numbers of SRARP are associated with worse cancer outcome. Moreover, DNA hypermethylation and lower expression of SRARP in normal adjacent tissues predict poor survival, suggesting that SRARP inactivation is an early event in carcinogenesis. In summary, SRARP and HSPB7 are tumor suppressors that are commonly inactivated in malignancies. SRARP inactivation is an early event in carcinogenesis that is strongly associated with worse survival, presenting potential translational applications.

Overexpression of the 14-3-3γ protein in uterine leiomyoma cells results in growth retardation and increased apoptosis

Protein 14-3-3γ was significantly reduced in human uterine leiomyoma compared to the adjacent normal myometrium tissue. To investigate the possible link between the reduced 14-3-3γ expression and uterine leiomyoma growth, we have overexpressed 14-3-3γ protein in uterine leiomyomal cells and its effects on cell proliferation and apoptosis were analyzed. Over-expression of 14-3-3γ was achieved by transducing into two types of uterine leiomyoma cells (primary culture cells and immortal stem cells) with a 14-3-3γ expressing adenovirus vector. Differentially expressed proteins were screened by the proteomics tool (TMT-LCTMS), followed by PANTHER database analysis to single out specifically modified signaling pathway proteins, which were confirmed by Phospho-MAPK Antibody Array and Western blots analysis. The results showed that increase in 14-3-3γ expression in both two types of human uterine leiomyoma cells inhibited cell proliferation and induced apoptosis. Proteomic screening has found 42 proteins, among 5846, that were significantly affected. PANTHER database and GeneMANIA analysis of the differentially expressed proteins have found that proteins involved in apoptosis signaling and cytoskeletal/adhesion were among the ones affected the most. Further analysis of the key signaling pathways have found that over-expression of 14-3-3γ resulted in reductions in the phosphorylations of multiple signaling molecules, including AKT, pan, ERK1/2, GSK-3 α/β, MEK1/2, Foxo1 and Vimentin. In conclusion, the loss of 14-3-3γ may have causal effects on the growth of uterine leiomyoma, which may function through modifying multiple signaling pathways, including AKT-Foxo and/or MEK1/2-ERK1/2.

14-3-3 proteins: an important regulator of autophagy in diseases

Autophagy is a cell digestion process that determines cell fate by promoting cell survival or inducing cell death in a cell context-dependent manner. Several classical signaling pathways, such as phosphoinositide-3-kinase and mammalian target of rapamycin, tightly regulate autophagy. 14-3-3 proteins regulate various signaling pathways by phosphorylation-dependent binding with partner proteins. 14-3-3 proteins also regulate autophagy by binding with autophagy-related proteins such as Beclin-1 and hVPS34. This review summarizes the role of 14-3-3 proteins in the control of autophagy in cancer, neurodegenerative diseases and other pathological conditions.

Small-Molecule Stabilization of 14-3-3 Protein-Protein Interactions Stimulates Axon Regeneration

Damaged central nervous system (CNS) neurons have a poor ability to spontaneously regenerate, causing persistent functional deficits after injury. Therapies that stimulate axon growth are needed to repair CNS damage. 14-3-3 adaptors are hub proteins that are attractive targets to manipulate cell signaling. We identify a positive role for 14-3-3s in axon growth and uncover a developmental regulation of the phosphorylation and function of 14-3-3s. We show that fusicoccin-A (FC-A), a small-molecule stabilizer of 14-3-3 protein-protein interactions, stimulates axon growth in vitro and regeneration in vivo. We show that FC-A stabilizes a complex between 14-3-3 and the stress response regulator GCN1, inducing GCN1 turnover and neurite outgrowth. These findings show that 14-3-3 adaptor protein complexes are druggable targets and identify a new class of small molecules that may be further optimized for the repair of CNS damage.

Cortactin deficiency causes increased RhoA/ROCK1-dependent actomyosin contractility, intestinal epithelial barrier dysfunction, and disproportionately severe DSS-induced colitis

The intestinal epithelium constitutes a first line of defense of the innate immune system. Epithelial dysfunction is a hallmark of intestinal disorders such as inflammatory bowel diseases (IBDs). The actin cytoskeleton controls epithelial barrier integrity but the function of actin regulators such as cortactin is poorly understood. Given that cortactin controls endothelial permeability, we hypothesized that cortactin is also important for epithelial barrier regulation. We found increased permeability in the colon of cortactin-KO mice that was accompanied by reduced levels of ZO-1, claudin-1, and E-cadherin. By contrast, claudin-2 was upregulated. Cortactin deficiency increased RhoA/ROCK1-dependent actomyosin contractility, and inhibition of ROCK1 rescued the barrier defect. Interestingly, cortactin deficiency caused increased epithelial proliferation without affecting apoptosis. KO mice did not develop spontaneous colitis, but were more susceptible to dextran sulfate sodium colitis and showed severe colon tissue damage and edema formation. KO mice with colitis displayed strong mucus deposition and goblet cell depletion. In healthy human colon tissues, cortactin co-localized with ZO-1 at epithelial cell contacts. In IBDs patients, we observed decreased cortactin levels and loss of co-localization with ZO-1. Thus, cortactin is a master regulator of intestinal epithelial barrier integrity in vivo and could serve as a suitable target for pharmacological intervention in IBDs.

A Circular RNA Binds To and Activates AKT Phosphorylation and Nuclear Localization Reducing Apoptosis and Enhancing Cardiac Repair

As central nodes in cardiomyocyte signaling, nuclear AKT appears to play a cardio-protective role in cardiovascular disease. Here we describe a circular RNA, circ-Amotl1 that is highly expressed in neonatal human cardiac tissue, and potentiates AKT-enhanced cardiomyocyte survival. We hypothesize that circ-Amotl1 binds to PDK1 and AKT1, leading to AKT1 phosphorylation and nuclear translocation. In primary cardiomyocytes, epithelial cells, and endothelial cells, we found that forced circ-Amotl1 expression increased the nuclear fraction of pAKT. We further detected increased nuclear pAKT in circ-Amotl1-treated hearts. In vivo, circ-Amotl1 expression was also found to be protective against Doxorubicin (Dox)-induced cardiomyopathy. Putative PDK1- and AKT1-binding sites were then identified in silico. Blocking oligonucleotides could reverse the effects of exogenous circ-Amotl1. We conclude that circ-Amotl1 physically binds to both PDK1 and AKT1, facilitating the cardio-protective nuclear translocation of pAKT.

pVHL suppresses Akt/β-catenin-mediated cell proliferation by inhibiting 14-3-3ζ expression

The mechanisms controlling degradation of cytosolic β-catenin are important for regulating β-catenin co-transcriptional activity. Loss of von Hippel–Lindau protein (pVHL) has been shown to stabilize β-catenin, increasing β-catenin transactivation and β-catenin-mediated cell proliferation. However, the role of phosphoinositide 3-kinase (PI3K)/Akt in the regulation of β-catenin signaling downstream from pVHL has never been addressed. Here, we report that hyperactivation of PI3K/Akt in cells lacking pVHL contributes to the stabilization and nuclear accumulation of active β-catenin. PI3K/Akt hyperactivation is facilitated by the up-regulation of 14-3-3ζ and the down-regulation of 14-3-3ε, 14-3-3η and 14-3-3θ. Up-regulation of 14-3-3ζ in response to pVHL is important for the recruitment of PI3K to the cell membrane and for stabilization of soluble β-catenin. In contrast, 14-3-3ε and 14-3-3η enhanced PI3K/Akt signaling by inhibiting PI3K and PDK1, respectively. Thus, our results demonstrated that 14-3-3 family members enhance PI3K/Akt/β-catenin signaling in order to increase proliferation. Inhibition of Akt activation and/or 14-3-3 function strongly reduces β-catenin signaling and decreases cell proliferation. Thus, inhibition of Akt and 14-3-3 function efficiently reduces cell proliferation in 786-0 cells characterized by hyperactivation of β-catenin signaling due to pVHL loss.

CUE domain-containing protein 2 promotes the Warburg effect and tumorigenesis

Cancer progression depends on cellular metabolic reprogramming as both direct and indirect consequence of oncogenic lesions; however, the underlying mechanisms are still poorly understood. Here, we report that CUEDC2 (CUE domain-containing protein 2) plays a vital role in facilitating aerobic glycolysis, or Warburg effect, in cancer cells. Mechanistically, we show that CUEDC2 upregulates the two key glycolytic proteins GLUT3 and LDHA via interacting with the glucocorticoid receptor (GR) or 14-3-3ζ, respectively. We further demonstrate that enhanced aerobic glycolysis is essential for the role of CUEDC2 to drive cancer progression. Moreover, using tissue microarray analysis, we show a correlation between the aberrant expression of CUEDC2, and GLUT3 and LDHA in clinical HCC samples, further demonstrating a link between CUEDC2 and the Warburg effect during cancer development. Taken together, our findings reveal a previously unappreciated function of CUEDC2 in cancer cell metabolism and tumorigenesis, illustrating how close oncogenic lesions are intertwined with metabolic alterations promoting cancer progression.

The pro-inflammatory cytokines IFNγ/TNFα increase chromogranin A-positive neuroendocrine cells in the colonic epithelium

The gastrointestinal tract is the largest hormone-producing organ in the body due to a specialized cell population called enteroendocrine cells (EECs). The number of EECs increases in the mucosa of inflammatory bowel disease patients; however, the mechanisms responsible for these changes remain unknown. Here, we show that the pro-inflammatory cytokines interferon γ (IFNγ) and tumor necrosis factor α (TNFα) or dextran sulfate sodium (DSS)-induced colitis increase the number of EECs producing chromogranin A (CgA) in the colonic mucosa of C57BL/6J mice. CgA-positive cells were non-proliferating cells enriched with inactive phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and autophagy markers. Moreover, inhibition of Akt and autophagy prevented the increase in CgA-positive cells after IFNγ/TNFα treatment. Similarly, we observed that CgA-positive cells in the colonic mucosa of patients with colitis expressed Akt and autophagy markers. These findings suggest that Akt signaling and autophagy control differentiation of the intestinal EEC lineage during inflammation.