Characterizing ambulatory function in children with PPP2R5D-related neurodevelopmental disorder

BACKGROUND

Individuals with PPP2R5D-related neurodevelopmental disorder have an atypical gait pattern characterized by ataxia and incoordination. Structured, quantitative assessments are needed to further understand the impact of these impairments on function.

RESEARCH QUESTION

How do gait parameters and ambulatory function of individuals with PPP2R5D-related neurodevelopmental disorder compare to age and sex matched healthy norms?

METHODS

Twenty-six individuals with PPP2R5D pathogenic genetic variants participated in this observational, single visit study. Participants completed at least one of the following gait assessments: quantitative gait analysis at three different speeds (preferred pace walking (PPW), fast paced walking (FPW) and running, six-minute walk test (6MWT), 10-meter walk run (10MWR), and timed up and go (TUG). Descriptive statistics were used to summarize gait variables. Percent of predicted values were calculated using published norms. Paired t-tests and regression analyses were used to compare gait variables.

RESULTS

The median age of the participants was 8 years (range 4-27) and eighteen (69.2 %) were female. Individuals with PPP2R5D-related neurodevelopmental disorder walked slower and with a wider base of support than predicted for their age and sex. Stride velocity ranged from 48.9 % to 70.1 % and stride distance from 58.5 % to 81.9 % of predicted during PPW. Percent of predicted distance walked on the 6MWT ranged from 30.6 % to 71.1 % representing varied walking impairment. Increases in stride distance, not cadence, were associated with changes in stride velocity in FPW (R2 = 0.675, p =< 0.001) and running conditions (R2 = 0.918, p =< 0.001).

SIGNIFICANCE

We quantitatively assessed the abnormal gait in individuals with PPP2R5D-related neurodevelopmental disorder. These impairments may affect ability to adapt to environmental changes and participation in daily life. Rehabilitative interventions targeting gait speed and balance may improve function and safety for individuals with PPP2R5D-related neurodevelopmental disorder.

Sit4 Genetically Interacts with Vps27 to Regulate Mitochondrial Function and Lifespan in Saccharomyces cerevisiae

The Sit4 protein phosphatase plays a key role in orchestrating various cellular processes essential for maintaining cell viability during aging. We have previously shown that SIT4 deletion promotes vacuolar acidification, mitochondrial derepression, and oxidative stress resistance, increasing yeast chronological lifespan. In this study, we performed a proteomic analysis of isolated vacuoles and yeast genetic interaction analysis to unravel how Sit4 influences vacuolar and mitochondrial function. By employing high-resolution mass spectrometry, we show that sit4Δ vacuolar membranes were enriched in Vps27 and Hse1, two proteins that are part of the endosomal sorting complex required for transport-0. In addition, SIT4 exhibited a negative genetic interaction with VPS27, as sit4∆vps27∆ double mutants had a shortened lifespan compared to sit4∆ and vps27∆ single mutants. Our results also show that Vps27 did not increase sit4∆ lifespan by improving protein trafficking or vacuolar sorting pathways. However, Vps27 was critical for iron homeostasis and mitochondrial function in sit4∆ cells, as sit4∆vps27∆ double mutants exhibited high iron levels and impaired mitochondrial respiration. These findings show, for the first time, cross-talk between Sit4 and Vps27, providing new insights into the mechanisms governing chronological lifespan.

Non-negligible inhibition effect of microcystin-LR biodegradation products target to protein phosphatase 2A

Though biodegradation is an important regulation pathway for microcystins (MCs) pollution, more consideration needs to be given to the potential risk associated with related biodegradation products (MC-BDPs). In this work, typical MCLR-BDPs were prepared and their toxicity was evaluated by protein phosphatases (PPs) inhibition assay. Results showed the initial ring opening of MCLR played a crucial role in detoxification. However, partial MCLR-BDPs still retained the critical structures and thus exhibited certain toxicity (2.8-43.5% of MCLR). With the aid of molecular simulation, the mechanism for the potential toxicity of BDPs targeting PP2A was elucidated. The initial ring opening made the loss of hydrogen bond Leu2←Arg89, and pi-H bond Adda5-His191, which was responsible for the significant reduction in the toxicity of MCLR-BDP. However, the key hydrogen bonds MeAsp3←Arg89, Glu6←Arg89, Adda5←Asn117, Adda5←His118, Arg4→Pro213, Arg4←Arg214, Ala1←Arg268, and Mdha7←Arg268, metal bond Glu6-Mn12+, and ionic bonds Glu6-Arg89, and Glu6-Mn22+ were preserved in varying degrees. Above preserved interactions maintained the interactions between PP2A and Mn2+ ions (reducing the exposure of Mn2+ ions). Above preserved interactions also hindered the combination of phosphate groups to Arg214 residual and thus exhibited potential toxicity.

Caregiver-reported dental manifestations in individuals with genetic neurodevelopmental disorders

BACKGROUND

Children with neurodevelopmental disorders (NDDs) often have poor oral health and dental abnormalities. An increasing number of genes have been associated with neurodevelopmental conditions affecting the oral cavity, but the specific dental features associated with many genes remain unknown.

AIM

To report the types and frequencies of dental manifestations in children with neurodevelopmental conditions of known genetic cause.

DESIGN

A 30-question survey assesing ectodermal and dental features was administered through Simons Searchlight, with which formed a recontactable cohort of individuals with genetic NDDs often associated with autism spectrum disorder (ASD).

RESULTS

Data were collected from a largely paediatric population with 620 affected individuals across 39 genetic conditions and 145 unaffected siblings without NDDs for comparison. Drooling, difficulty accessing dental care, late primary teeth eruption, abnormal primary and permanent teeth formation, misshapen nails, and hair loss were more frequent in individuals with NDDs. Additionally, we evidenced an association between three new pathogenic gene variant/oral manifestation pairs: CSNK2A1/unusual primary teeth, DYRK1A/late primary teeth eruption, and PPP2R5D/sialorrhea.

CONCLUSION

Our results demonstrate that genetic NDDs caused by mutations in CSNK2A1, DYRK1A, and PP2R5D are associated with unique dental manifestations, and knowledge of these features can be helpful to personalize dental care.

Pharmacogenomics of intravenous immunoglobulin response in Kawasaki disease

Introduction

Kawasaki disease (KD) is a diffuse vasculitis in children. Response to high dose intravenous gamma globulin (IVIG), the primary treatment, varies according to genetic background. We sought to identify genetic loci, which associate with treatment response using whole genome sequencing (WGS).

Method

We performed WGS in 472 KD patients with 305 IVIG responders and 167 non-responders defined by AHA clinical criteria. We conducted logistic regression models to test additive genetic effect in the entire cohort and in four subgroups defined by ancestry information markers (Whites, African Americans, Asians, and Hispanics). We performed functional mapping and annotation using FUMA to examine genetic variants that are potentially involved IVIG non-response. Further, we conducted SNP-set [Sequence] Kernel Association Test (SKAT) for all rare and common variants.

Results

Of the 43,288,336 SNPs (23,660,970 in intergenic regions, 16,764,594 in introns and 556,814 in the exons) identified, the top ten hits associated with IVIG non-response were in FANK1, MAP2K3:KCNJ12, CA10, FRG1DP, CWH43 regions. When analyzed separately in ancestry-based racial subgroups, SNPs in several novel genes were associated. A total of 23 possible causal genes were pinpointed by positional and chromatin mapping. SKAT analysis demonstrated association in the entire MANIA2, EDN1, SFMBT2, and PPP2R5E genes and segments of CSMD2, LINC01317, HIVEPI, HSP90AB1, and TTLL11 genes.

Conclusions

This WGS study identified multiple predominantly novel understudied genes associated with IVIG response. These data can serve to inform regarding pathogenesis of KD, as well as lay ground work for developing treatment response predictors.

Fly clock, my clock, and lamin B receptor

In the fruit fly Drosophila melanogaster, circadian rhythm was disrupted when the inner nuclear membrane protein lamin B receptor (LBR) was depleted from its clock neurons (Proc. Natl. Acad. Sci. USA 118, e2019756118. 2021; https://doi.org/10. 1073/pnas.2019756118 and Research 6, 0139, 2023; https://doi.org/10.34133/research.0139). Ordinarily, the clock proteinPERIOD (PER) forms foci close to the inner nuclear membrane in the circadian clock's repression phase. The size, number, and location of foci near the nuclear membrane oscillate with a 24-h rhythm. When LBR was absent the foci did not form. The PER foci bring per and other clock genes close to the nuclear envelope, where their transcription is silenced. Then, in the circadian clock's activation phase, the PER protein gradually gets degraded and the foci disappear. The clock genes, including per, relocate to the nucleus interior where they resume transcription. Rhythmic re-positioning of clock genes between nucleus periphery and interior, correlates with their repression and activation in the circadian cycle. Absence of LBR disrupted this rhythm. Phosphorylation of PER promoted the formation of foci whereas dephosphorylation by protein phosphatase 2A causedthem to disappear. LBR promoted focus formation by destabilizing the catalytic subunit of protein phosphatase 2A. The lbr gene is no stranger to this journal. The first hint that vertebrate LBR is also a sterol biosynthesis enzyme, specifically, a sterol C14 reductase, was reported here (J. Genet. 73, 33-41, 1994; https://www.ias.ac.in/article/fulltext/jgen/073/01/0033-0041). Mutations in the human Lbr gene cause a range of phenotypes--from the relatively benign Pelger-Huet anomaly to the perinatally lethal Greenberg skeletal dysplasia.Drosophila, like all insects, is a sterol auxotroph. The fly orthologue of vertebrate lbr genes encodes a protein (dLBR) that shares several properties with vertebrate LBR proteins, with one notable exception. While human LBR complemented theyeast Saccharomyces cerevisiae erg24 mutant which lacks sterol C14 reductase activity, dLBR did not (J. Cell. Sci. 117, 2015-28, 2004; https://doi.org/10.1242/jcs.01052). Despite not possessing sterol reductase activity, dLBR retains significant sequence homology with vertebrate LBRs which have this activity. An undergraduate summer trainee in my laboratory obtained early (unpublished) evidence that dLBR lost sterol reductase activity during evolution. She transferred adult drosophila flies to vials containing a medium made of agar, dextrose, and dried and powdered mycelium of the filamentous fungus Neurospora crassa. On medium made with wild-type mycelium, theflies mated, laid eggs, hatched larvae, and developed pupae which eclosed progeny adult flies. The life cycle was no different than on 'regular' fly food composed of agar, dextrose and yeast extract. However, on a medium made with mycelium from a sterol C14 reductase null mutant, the flies laid eggs which hatched and released larvae, but the larvae failed to pupate, and no adult progeny flies emerged. This was because the fly lacks a sterol C14 reductase. The wild-type sterol, ergosterol, is a precursor of the steroid hormone ecdysone needed for molting and metamorphosis. Can expression of vertebrate LBR in dLBR-depleted fly clock neurons restore circadian rhythm? Can expression of vertebrate LBR enable flies to complete their life cycle on mutant Neurospora medium? Does LBR regulate the vertebrate clock in a like manner? If yes, then is the sterol reductase activity dispensable in this role? These are some questions that came to my mind on a recent morning walk. The walk itself was a much-cherished outcome of my circadian clock.

White spot syndrome virus hijacks host PP2A-FOXO axes to promote its propagation

Viruses have developed superior strategies to escape host defenses or exploit host components and enable their infection. The forkhead box transcription factor O family proteins (FOXOs) are reportedly utilized by human cytomegalovirus during their reactivation in mammals, but if FOXOs are exploited by viruses during their infection remains unclear. In the present study, we found that the FOXO of kuruma shrimp (Marsupenaeus japonicus) was hijacked by white spot syndrome virus (WSSV) during infection. Mechanistically, the expression of leucine carboxyl methyl transferase 1 (LCMT1) was up-regulated during the early stages of WSSV infection, which activated the protein phosphatase 2A (PP2A) by methylation, leading to dephosphorylation of FOXO and translocation into the nucleus. The FOXO directly promoted transcription of the immediate early gene, wsv079 of WSSV, which functioned as a transcriptional activator to initiate the expression of viral early and late genes. Thus, WSSV utilized the host LCMT1-PP2A-FOXO axis to promote its replication during the early infection stage. We also found that, during the late stages of WSSV infection, the envelope protein of WSSV (VP26) promoted PP2A activity by directly binding to FOXO and the regulatory subunit of PP2A (B55), which further facilitated FOXO dephosphorylation and WSSV replication via the VP26-PP2A-FOXO axis in shrimp. Overall, this study reveals novel viral strategies by which WSSV hijacks host LCMT1-PP2A-FOXO or VP26-PP2A-FOXO axes to promote its propagation, and provides clinical targets for WSSV control in shrimp aquaculture.

RNF149 confers cisplatin resistance in esophageal squamous cell carcinoma via destabilization of PHLPP2 and activating PI3K/AKT signalling

Chemo-resistance has been identified as a crucial factor contributing to tumor recurrence and a leading cause of worse prognosis in patients with ESCC. Therefore, unravel the critical regulators and effective strategies to overcome drug resistance will have a significant clinical impact on the disease. In our study we found that RNF149 was upregulated in ESCC and high RNF149 expression was associated with poor prognosis with ESCC patients. Functionally, we have demonstrated that overexpression of RNF149 confers CDDP resistance to ESCC; however, inhibition of RNF149 reversed this phenomenon both in vitro and in vivo. Mechanistically, we demonstrated that RNF149 interacts with PH domain and leucine rich repeat protein phosphatase 2 (PHLPP2) and induces E3 ligase-dependent protein degradation of PHLPP2, substantially activating the PI3K/AKT signalling pathway in ESCC. Additionally, we found that inhibition of PI3K/AKT signalling pathway by AKT siRNA or small molecule inhibitor significantly suppressed RNF149-induced CDDP resistance. Importantly, RNF149 locus was also found to be amplified not only in ESCC but also in various human cancer types. Our data suggest that RNF149 might function as an oncogenic gene. Targeting the RNF149/PHLPP2/PI3K/Akt axis may be a promising prognostic factor and valuable therapeutic target for malignant tumours.

Protein Phosphatase 2A as a Therapeutic Target in Pulmonary Diseases

New disease targets and medicinal chemistry approaches are urgently needed to develop novel therapeutic strategies for treating pulmonary diseases. Emerging evidence suggests that reduced activity of protein phosphatase 2A (PP2A), a complex heterotrimeric enzyme that regulates dephosphorylation of serine and threonine residues from many proteins, is observed in multiple pulmonary diseases, including lung cancer, smoke-induced chronic obstructive pulmonary disease, alpha-1 antitrypsin deficiency, asthma, and idiopathic pulmonary fibrosis. Loss of PP2A responses is linked to many mechanisms associated with disease progressions, such as senescence, proliferation, inflammation, corticosteroid resistance, enhanced protease responses, and mRNA stability. Therefore, chemical restoration of PP2A may represent a novel treatment for these diseases. This review outlines the potential impact of reduced PP2A activity in pulmonary diseases, endogenous and exogenous inhibitors of PP2A, details the possible PP2A-dependent mechanisms observed in these conditions, and outlines potential therapeutic strategies for treatment. Substantial medicinal chemistry efforts are underway to develop therapeutics targeting PP2A activity. The development of specific activators of PP2A that selectively target PP2A holoenzymes could improve our understanding of the function of PP2A in pulmonary diseases. This may lead to the development of therapeutics for restoring normal PP2A responses within the lung.

Does modulation of tau hyperphosphorylation represent a reasonable therapeutic strategy for Alzheimer's disease? From preclinical studies to the clinical trials

Protein kinases (PKs) have emerged as one of the most intensively investigated drug targets in current pharmacological research, with indications ranging from oncology to neurodegeneration. Tau protein hyperphosphorylation was the first pathological post-translational modification of tau protein described in Alzheimer's disease (AD), highlighting the role of PKs in neurodegeneration. The therapeutic potential of protein kinase inhibitors (PKIs)) and protein phosphatase 2 A (PP2A) activators in AD has recently been explored in several preclinical and clinical studies with variable outcomes. Where a number of preclinical studies demonstrate a visible reduction in the levels of phospho-tau in transgenic tauopathy models, no reduction in neurofibrillary lesions is observed. Amongst the few PKIs and PP2A activators that progressed to clinical trials, most failed on the efficacy front, with only a few still unconfirmed and potential positive trends. This suggests that robust preclinical and clinical data is needed to unequivocally evaluate their efficacy. To this end, we take a systematic look at the results of preclinical and clinical studies of PKIs and PP2A activators, and the evidence they provide regarding the utility of this approach to evaluate the potential of targeting tau hyperphosphorylation as a disease modifying therapy.

Activation of the PP2A-B56α heterocomplex synergizes with venetoclax therapies in AML through BCL2 and MCL1 modulation

Venetoclax combination therapies are becoming the standard of care in acute myeloid leukemia (AML). However, the therapeutic benefit of these drugs in older/unfit patients is limited to only a few months, highlighting the need for more effective therapies. Protein phosphatase 2A (PP2A) is a tumor suppressor phosphatase with pleiotropic functions that becomes inactivated in ∼70% of AML cases. PP2A promotes cancer cell death by modulating the phosphorylation state in a variety of proteins along the mitochondrial apoptotic pathway. We therefore hypothesized that pharmacological PP2A reactivation could increase BCL2 dependency in AML cells and, thus, potentiate venetoclax-induced cell death. Here, by using 3 structurally distinct PP2A-activating drugs, we show that PP2A reactivation synergistically enhances venetoclax activity in AML cell lines, primary cells, and xenograft models. Through the use of gene editing tools and pharmacological approaches, we demonstrate that the observed therapeutic synergy relies on PP2A complexes containing the B56α regulatory subunit, of which expression dictates response to the combination therapy. Mechanistically, PP2A reactivation enhances venetoclax-driven apoptosis through simultaneous inhibition of antiapoptotic BCL2 and extracellular signal-regulated kinase signaling, with the latter decreasing MCL1 protein stability. Finally, PP2A targeting increases the efficacy of the clinically approved venetoclax and azacitidine combination in vitro, in primary cells, and in an AML patient-derived xenograft model. These preclinical results provide a scientific rationale for testing PP2A-activating drugs with venetoclax combinations in AML.

PP1, PP2A and PP2B Interplay in the Regulation of Sperm Motility: Lessons from Protein Phosphatase Inhibitors

Male fertility relies on the ability of spermatozoa to fertilize the egg in the female reproductive tract (FRT). Spermatozoa acquire activated motility during epididymal maturation; however, to be capable of fertilization, they must achieve hyperactivated motility in the FRT. Extensive research found that three protein phosphatases (PPs) are crucial to sperm motility regulation, the sperm-specific protein phosphatase type 1 (PP1) isoform gamma 2 (PP1γ2), protein phosphatase type 2A (PP2A) and protein phosphatase type 2B (PP2B). Studies have reported that PP activity decreases during epididymal maturation, whereas protein kinase activity increases, which appears to be a requirement for motility acquisition. An interplay between these PPs has been extensively investigated; however, many specific interactions and some inconsistencies remain to be elucidated. The study of PPs significantly advanced following the identification of naturally occurring toxins, including calyculin A, okadaic acid, cyclosporin, endothall and deltamethrin, which are powerful and specific PP inhibitors. This review aims to overview the protein phosphorylation-dependent biochemical pathways underlying sperm motility acquisition and hyperactivation, followed by a discussion of the PP inhibitors that allowed advances in the current knowledge of these pathways. Since male infertility cases still attain alarming numbers, additional research on the topic is required, particularly using other PP inhibitors.

PP2ARts1 antagonizes Rck2-mediated hyperosmotic stress signaling in yeast

In Saccharomyces cerevisiae, impairment of protein phosphatase PP2ARts1 leads to temperature and hyperosmotic stress sensitivity, yet the underlying mechanism and the scope of action of the phosphatase in the stress response remain elusive. Using a quantitative mass spectrometry-based approach we have identified a set of putative substrate proteins that show both hyperosmotic stress- and PP2ARts1-dependent changes in their phosphorylation pattern. A comparative analysis with published MS-shotgun data revealed that the phosphorylation status of many of these sites is regulated by the MAPKAP kinase Rck2, suggesting that the phosphatase antagonizes Rck2 signaling. Detailed gel mobility shift assays and protein-protein interaction analysis strongly indicate that Rck2 activity is directly regulated by PP2ARts1 via a SLiM B56-family interaction motif, revealing how PP2ARts1 influences the response to hyperosmotic stress in Yeast.

Hypoglycemia due to PI3K/AKT/mTOR signaling pathway defects: two novel cases and review of the literature

INTRODUCTION

The PI3K/AKT/mTOR signaling pathway is important for the regulation of multiple biological processes, including cellular growth and glucose metabolism. Defects of the PI3K/AKT/mTOR signaling pathway are not usually considered among the genetic causes of recurrent hypoglycemia in childhood. However, accumulating evidence links hypoglycemia with defects of this pathway.

CASE REPORTS AND REVIEW

We describe here two cases of macrocephaly and hypoglycemia bearing genetic defects in genes involved in the PI3K/AKT/mTOR pathway. The first patient was diagnosed with a PTEN hamartoma tumour syndrome (PTHS) due to the de novo germline missense mutation c.[492 + 1G > A] of the PTEN gene. The second patient presented the autosomal dominant mental retardation-35 (MDR35) due to the heterozygous missense mutation c.592G > A in the PPP2R5D gene. A review of the literature on hypoglycemia and PI3K/AKT/mTOR signaling pathway defects, with a special focus on the metabolic characterization of hypoglycemia, is included.

CONCLUSIONS

PI3K/AKT/mTOR pathway defects should be included in the differential diagnosis of patients with hypoglycemia and macrocephaly. Clinical suspicion and molecular confirmation are important, not just for an accurate genetic counselling but also for defining the follow-up management, including cancer surveillance. The biochemical profile of hypoglycemia varies among patients. While most patients are characterized by low plasmatic insulin levels, hyperinsulinemia has also been observed. Large patient cohorts are needed to gain a comprehensive profile of the biochemical patterns of hypoglycemia in such defects and eventually guide targeted therapeutic interventions.

Relationship between osteoporosis and benign paroxysmal positional vertigo based on evidence-based medicine and bioinformatics

It has been reported that osteoporosis is a possible risk factor of benign paroxysmal positional vertigo (BPPV).

PURPOSE

We analyzed the correlation between osteoporosis and BPPV and the possible mechanism by performing evidence-based medicine meta-analysis and bioinformatics analysis.

METHODS

Initially, English articles related to osteoporosis and BPPV were obtained through PubMed and EMBASE databases. Stata12.0 software was used for meta-analysis to calculate the odd ratio (OR) and 95% confidence interval (CI) of outcome indicators, and the heterogeneity was evaluated by subgroup analysis, publication bias evaluation, and sensitivity analysis. In addition, microarray datasets related to BPPV and osteoporosis were obtained from gene expression omnibus (GEO) database to screen differentially expressed genes. At last, a mouse model of osteoporosis was established by bilateral oophorectomy for validation. RT-qPCR and Western blot analysis were performed to determine expression of related factors in mouse tissues.

RESULTS

Osteoporosis was suggested as an important risk factor for BPPV through meta-analysis of these 12 articles. It was found that PPP2CA was upregulated in BPPV and low bone mineral density (BMD) samples. Moreover, PPP2CA induced dephosphorylation of BCL2, which may be involved in BPPV through regulation of BMD. Through this mechanism, silencing of PPP2CA could elevate the incidence of BPPV by promoting bone remodeling and reducing the density of otoconia around the macula.

CONCLUSIONS

PPP2CA reduces BMD expression by inducing dephosphorylation of BCL2, which may be one of the mechanisms responsible for the onset of BPPV in osteoporosis.

1HN, 13C, and 15N backbone resonance assignments of the SET/TAF-1β/I2PP2A oncoprotein (residues 23-225)

SET (TAF-1β/I2PP2A) is a ubiquitously expressed, multifunctional protein that plays a role in regulating diverse cellular processes, including cell cycle progression, migration, apoptosis, transcription, and DNA repair. SET expression is ubiquitous across all cell types. However, it is overexpressed or post-translationally modified in several solid tumors and blood cancers, where expression levels are correlated with worsening clinical outcomes. SET exerts its oncogenic effects primarily through the formation of antagonistic protein complexes with the tumor suppressor, protein phosphatase 2A (PP2A), and the well-known metastasis suppressor, nm23-H1. PP2A inhibition is often observed as a secondary driver of tumorigenesis and metastasis in human cancers. Preclinical studies have shown that the pharmacological reactivation of PP2A combined with potent inhibitors of the primary driver oncogene produces synergistic cell death and decreased drug resistance. Therefore, the development of novel inhibitors of the SET-PP2A interaction presents an attractive approach to reactivation of PP2A, and thereby, tumor suppression. NMR provides a unique platform to investigate protein targets in their natively folded state to identify protein and small-molecule ligands and report on the protein internal dynamics. The backbone ¹H^N, ¹³C, and ¹⁵N NMR resonance assignments were completed for the 204 amino acid nucleosome assembly protein-1 (NAP-1) domain of the human SET oncoprotein (residues 23-225). These assignments provide a vital first step toward the development of novel PP2A reactivators via SET-selective inhibition.

Survival-associated alternative splicing events interact with the immune microenvironment in stomach adenocarcinoma

BACKGROUND

Alternative splicing (AS) increases the diversity of mRNA during transcription; it might play a role in alteration of the immune microenvironment, which could influence the development of immunotherapeutic strategies against cancer.

AIM

To obtain the transcriptomic and clinical features and AS events in stomach adenocarcinoma (STAD) from the database. The overall survival data associated with AS events were used to construct a signature prognostic model for STAD.

METHODS

Differentially expressed immune-related genes were identified between subtypes on the basis of the prognostic model. In STAD, 2042 overall-survival-related AS events were significantly enriched in various pathways and influenced several cellular functions. Furthermore, the network of splicing factors and overall-survival-associated AS events indicated potential regulatory mechanisms underlying the AS events in STAD.

RESULTS

An eleven-AS-signature prognostic model (CD44|14986|ES, PPHLN1|21214|AT, RASSF4|11351|ES, KIAA1147|82046|AP, PPP2R5D|76200|ES, LOH12CR1|20507|ES, CDKN3|27569|AP, UBA52|48486|AD, CADPS|65499|AT, SRSF7| 53276|RI, and WEE1|14328|AP) was constructed and significantly related to STAD overall survival, immune cells, and cancer-related pathways. The differentially expressed immune-related genes between the high- and low-risk score groups were significantly enriched in cancer-related pathways.

CONCLUSION

This study provided an AS-related prognostic model, potential mechanisms for AS, and alterations in the immune microenvironment (immune cells, genes, and pathways) for future research in STAD.

Deciphering the Influence of Cigarette Smoke Carcinogens on CNS Associated Biomolecules: A Computational Synergistic Approach

BACKGROUND

Human health issues caused by Cigarette Smoke Carcinogens (CSC) are increasing rapidly every day and challenging the scientific community to provide a better understanding in order to avoid its impact on communities. Cigarette smoke also contains tobacco-based chemical compounds harmful to human beings, either smokers or non-smokers.

OBJECTIVE

We have tested 7H-Dibenzo[c,g]carbazole (7H-DBC) and Dibenz[a,h]acridine (DBAD) derivatives of Asz-arenes along with N'-Nitrosoanabasine (NAB) and N-Nitrosoanatabine (NAT) derivatives of N-Nitrosamines molecular interaction with CNS biomolecules.

METHODS

Computational synergistic approaches like system biology and molecular interaction techniques were implemented to conduct the analysis.

RESULTS

CSC efficiently interacted with NRAS, KRAS, CDH1, and RAC1 molecular targets in CNS. We have also performed the interactome analysis followed by system biology approaches and found that HSPA8 is the most important hub protein for the network generated for CSC-hampered genes of CNS. We have also identified 6 connector proteins, namely TP53, HSP90AA1, PPP2CA, CDH1, CTNNB1, and ARRB1. Further analysis revealed that NRAS and CDH1 have maximum interactions with all the selected CSC.

CONCLUSION

The obtained structural analysis data could be utilized to assess the carcinogenic effect of CSC and could be useful in the treatment of CNS diseases and disorders induced, especially by tobacco-specific carcinogens, or it could also be used in vivo/ in vitro experimentation model designing.

Microcystin-leucine arginine exhibits immunomodulatory roles in testicular cells resulting in orchitis

Microcystin-leucine arginine (MC-LR) causes testicular inflammation and hinders spermatogenesis. However, the molecular mechanisms underlying the immune responses to MC-LR in the testis have not been elucidated in detail. In this study, we show that MC-LR induced immune responses in Sertoli cells (SC), germ cells (GC), and Leydig cells (LC) via activating phosphatidylinositol 3-kinase (PI3K)/AKT/nuclear factor kappa B (NF-κB), resulting in the production of pro-inflammatory cytokines and chemokines including tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and chemokine (C-X-C motif) ligand 10 (CXCL10). The observed effects were attributed to reduced activity of protein phosphatases 2A (PP2A) as a result of binding of MC-LR to the catalytic subunit of PP2A in SC and GC. By contrast, innate immune responses were triggered by Toll-like receptor 2 (TLR2) in LC because MC-LR could not enter into the LC and subsequently inhibit the PP2A activity. PI3K/AKT/NF-κB were also activated in SC, GC, and LC in vivo, with the enrichment of TNF-α, IL-6, MCP-1, and CXCL10 in the testis. Following chronic exposure, MC-LR-treated mice exhibited decreased sperm counts and abnormal sperm morphology. Our data demonstrate that MC-LR can activate innate immune responses in testicular cells, which provides novel insights to explore the mechanism associated with MC-LR-induced orchitis.

Interrelationship between Protein Phosphatase-2A and Cytoskeletal Architecture during the Endothelial Cell Response to Soluble Products Produced by Human Head and Neck Cancer

Tumor neovascularization is necessary for the progressive development of all solid tumors, including head and neck squamous cell carcinomas (HNSCCs). The angiogenic process includes increased endothelial cell motility. Our prior studies have shown the importance of protein phos-phatase-2A (PP-2A) in restricting endothelial cell motility. Because motility is regulated by the polymerization/depolymerization of the cellular cytoskeleton, the present study defined the interrelationship between PP-2A and the cytoskeleton during endothelial cell responses to HNSCC-derived angiogenic factors. PP-2A was shown to colocalize with microtubules of unstimulated endothelial cells. However, exposure to HNSCC-derived products resulted in a more diffuse distribution of PP-2A staining and a loss of filamentous tubulin. The feasibility of pharmacologically preventing this cytoskeletal disorganization as a means of blocking tumor-induced angiogenesis was tested. This was accomplished by use of 1α,25-dihydroxyvitamin D3[1,25 (OH)2D3] and all- trans-retinoic acid to indirectly stimulate PP-2A activity through their capacity to elevated intracellular levels of the second messenger ceramide. Pretreatment of endothelial cells with either 1,25(OH)2D3or retinoic acid prevented the cytoskeletal disorganization that otherwise occurs in endothelial cells on exposure to HNSCC-derived products. These studies support the feasibility of using elevation of PP-2A to prevent the mor-phogenic component of the angiogenic process that is stimulated by HNSCC-derived factors.

[The role of protein phosphatase 2A B56β holoenzyme in the regulation of heavy metal CdCl2 induced cytotoxicity]

OBJECTIVE

To investigate the role of holoenzyme containing Protein Phosphatase 2A B56β in regulating CdCl2 induced cytotoxicity.

METHOD

CdCl2-induced cytotoxicity in normal human cell line L-02, AFB1-transformed hepatic cell line L-02 RT-AFB1 and tumor cell line Bel7402 was measured by modified MTT assay. Stable cell lines L-02 SHAKT, L-02 SHB56β, L-02 RT-AFB1-B56β and Bel7402-B56β were generated by infecting L-02 cells or Bel7402 cells with retroviral vectors encoding lentiviral AKT shRNA, lentiviral B56β shRNA and B56β. The relative cell viability was measured in normal human cell line AFB1-transformed hepatic cell line and tumor cell line when treated by CdCl2 (0, 20, 40, 80, 160 µmol/L). After treated by wortmannin (2.5, 5.0 µmol/L) combined with 40 µmol/L CdCl2, Western blot was applied to measure the expression of associated protein in L-02.Western blot was applied to measure the expression of B56β, MT (metallothionein), AKT, and p-AKT in these cell lines treated by CdCl2.

RESULTS

The levels of MT were 0.12 ± 0.02, 0.06 ± 0.06 in L-02 RT-AFB1 and Bel7402, which were lower than L02 (0.92 ± 0.14) (F = 1 148.16, P < 0.001) when treated by 40 µmol/L CdCl2. When treated by 40 µmol/L CdCl2, the expression of p-AKT in L-02 SHAKT-1 and L-02 SHAKT-2 were 0.08 ± 0.02, 0.08 ± 0.05, which levels were lower than L-02 SHGFP (0.18 ± 0.15) (F = 724.70, P < 0.001); and the expression of MT were both 0.62 ± 0.16 in L-02 SHAKT-1 and L-02 SHAKT-2, which levels were higher than L-02 SHGFP (0.22 ± 0.14) (F = 94.73, P < 0.001). After treated by wortmannin (2.5, 5.0 µmol/L) combined with 40 µmol/L CdCl2, the expression of p-AKT in L-02 were 0.28 ± 0.07, 0.15 ± 0.11, which levels were lower than wortmannin untreated cells (0.52 ± 0.11) (F = 578.57, P < 0.001); and the expreesion of MT were 1.62 ± 0.80, 1.08 ± 0.15, which levels were higher than wortmannin untreated cells (0.69 ± 0.18) (F = 12.34, P < 0.001). When treated by 40 µmol/L CdCl2, the levels of p-AKT in L-02 SHB56β-1 and L-02 SHB56β-2 were 0.57 ± 0.13, 0.59 ± 0.02, which were higher than L-02 SHGFP (0.32 ± 0.02) (F = 87.16, P < 0.001); and the levels of MT were 0.35 ± 0.07, 0.20 ± 0.03 in L-02 SHB56β-1 and L-02 SHB56β-2, which were lower than L-02 SHGFP (1.51 ± 0.13) (F = 2 457.10, P < 0.001). After treated by 40 µmol/L CdCl2, the expression of p-AKT in L-02 RT-AFB1-B56β and Bel7402-B56β were 0.10 ± 0.11, 0.09 ± 0.01, which were lower than L-02 RT-AFB1 (0.36 ± 0.01) and Bel7402 (0.43 ± 0.11) (F = 877.62, P < 0.001); and the levels of MT were 0.92 ± 0.13, 0.95 ± 0.08 in L-02 RT-AFB1-B56β and Bel7402-B56β,which were higher than L-02 RT-AFB1 (0.44 ± 0.12) and Bel7402 (0.77 ± 0.06) (F = 51.97, P < 0.001).

CONCLUSION

Protein phosphatase 2A complexes containing B56β participated in the regulation of MT expression through direct dephosphorylation of AKT, finally affected the cytotoxicity responding to CdCl2. Our study revealed a key signaling pathways of PP2A involved in heavy metals induced cytotoxicity.

Characterization of Protein Phosphatase 2A Acting on Phosphorylated Plasma Membrane Aquaporin of Tulip Petals

A protein phosphatase holo-type enzyme (38, 65, and 75 kDa) preparation and a free catalytic subunit (38 kDa) purified from tulip petals were characterized as protein phosphatase 2A (PP2A) by immunological and biochemical approaches. The plasma membrane containing the putative plasma membrane aquaporin (PM-AQP) was prepared from tulip petals, phosphorylated in vitro, and used as the substrate for both of the purified PP2A preparations. Although both preparations dephosphorylated the phosphorylated PM-AQP at 20 degrees C, only the holo-type enzyme preparation acted at 5 degrees C on the phosphorylated PM-AQP with higher substrate specificity, suggesting that regulatory subunits are required for low temperature-dependent dephosphorylation of PM-AQP in tulip petals.