Leucine-rich Nuclear phosphoprotein-32A Research Articles

C/EBPβ: A transcription factor associated with the irreversible progression of Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative disorder distinguished by a swift cognitive deterioration accompanied by distinctive pathological hallmarks such as extracellular Aβ (β-amyloid) peptides, neuronal neurofibrillary tangles (NFTs), sustained neuroinflammation, and synaptic degeneration. The elevated frequency of AD cases and its proclivity to manifest at a younger age present a pressing challenge in the quest for novel therapeutic interventions. Numerous investigations have substantiated the involvement of C/EBPβ in the progression of AD pathology, thus indicating its potential as a therapeutic target for AD treatment. Several studies have demonstrated an elevation in the expression level of C/EBPβ among individuals afflicted with AD. Consequently, this review predominantly delves into the association between C/EBPβ expression and the pathological progression of Alzheimer's disease, elucidating its underlying molecular mechanism, and pointing out the possibility that C/EBPβ can be a new therapeutic target for AD. A systematic literature search was performed across multiple databases, including PubMed, Google Scholar, and so on, utilizing predetermined keywords and MeSH terms, without temporal constraints. The inclusion criteria encompassed diverse study designs, such as experimental, case-control, and cohort studies, restricted to publications in the English language, while conference abstracts and unpublished sources were excluded. Overexpression of C/EBPβ exacerbates the pathological features of AD, primarily by promoting neuroinflammation and mediating the transcriptional regulation of key molecular pathways, including δ-secretase, apolipoprotein E4 (APOE4), acidic leucine-rich nuclear phosphoprotein-32A (ANP32A), transient receptor potential channel 1 (TRPC1), and Forkhead BoxO (FOXO). The correlation between overexpression of C/EBPβ and the pathological development of AD, along with its molecular mechanisms, is evident. Investigating the pathways through which C/EBPβ regulates the development of AD reveals numerous multiple vicious cycle pathways exacerbating the pathological progression of the disease. Furthermore, the exacerbation of pathological progression due to C/EBPβ overexpression and its molecular mechanism is not limited to AD but also extends to other neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), and multiple sclerosis (MS). The overexpression of C/EBPβ accelerates the irreversible progression of AD pathophysiology. Additionally, C/EBPβ plays a crucial role in mediating multiple pathways linked to AD pathology, some of which engender vicious cycles, leading to the establishment of feedback mechanisms. To sum up, targeting C/EBPβ could hold promise as a therapeutic strategy not only for AD but also for other degenerative diseases.

Time- and Concentration-Dependent Stimulation of Oxidative Stress in Chondrocytes by Intracellular Soluble Urate.

Gout could result in irreversible bone erosion, and chondrocyte might be involved in the process. Increased soluble urate is the early stage of gout and is strongly oxidative. To explore the effect of intracellular urate on the oxidative status of chondrocytes. A chondrocyte model was used. Serial concentrations of exogenous urate were incubated with chondrocytes for increasing amounts of time. Reactive oxygen species (ROS), oxidant, and anti-oxidant molecules were measured with biochemical assays, rt-PCR, and western blot. A urate transport inhibitor and oxidative inhibitors were used to confirm the effect of exogenous urate. All concentrations of exogenous urate stimulated the production of ROS in a time- and concentration-dependent manner, as well as oxidant molecules, including hydrogen peroxide (H2O2), nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, nitric oxide (NO) inducible nitric oxide synthase (iNOS), and these effects, could be inhibited by oxidant inhibitors. However, anti-oxidant molecules, including acidic leucine-rich nuclear phosphoprotein-32A (ANP32A), ataxia-telangiectasia mutated (ATM), heme oxygenase-1 (HO-1), and the transcription factor nuclear factor erythroid 2 (NF-E2)-related (Nrf2), was decreased by high concentrations of exogenous urate after prolonged incubation, but not by low to medium concentrations of exogenous urate. By inhibiting soluble urate trafficking, benzbromarone significantly suppressed the effect of urate stimulus on the oxidant and anti-oxidant molecules. Intracellular soluble urate could regulate chondrocyte redox balance in a time and concentration-dependent manner, and would be a target for regulating and protecting chondrocyte function in the early gout stage.

Glaucoma-Associated CDR1 Peptide Promotes RGC Survival in Retinal Explants through Molecular Interaction with Acidic Leucine Rich Nuclear Phosphoprotein 32A (ANP32A).

Glaucoma is a complex, multifactorial optic neuropathy mainly characterized by the progressive loss of retinal ganglion cells (RGCs) and their axons, resulting in a decline of visual function. The pathogenic molecular mechanism of glaucoma is still not well understood, and therapeutic strategies specifically addressing the neurodegenerative component of this ocular disease are urgently needed. Novel immunotherapeutics might overcome this problem by targeting specific molecular structures in the retina and providing direct neuroprotection via different modes of action. Within the scope of this research, the present study showed for the first time beneficial effects of the synthetic CDR1 peptide SCTGTSSDVGGYNYVSWYQ on the viability of RGCs ex vivo in a concentration-dependent manner compared to untreated control explants (CTRL, 50 µg/mL: p < 0.05 and 100 µg/mL: p < 0.001). Thereby, this specific peptide was identified first as a potential biomarker candidate in the serum of glaucoma patients and was significantly lower expressed in systemic IgG molecules compared to healthy control subjects. Furthermore, MS-based co-immunoprecipitation experiments confirmed the specific interaction of synthetic CDR1 with retinal acidic leucine-rich nuclear phosphoprotein 32A (ANP32A; p < 0.001 and log2 fold change > 3), which is a highly expressed protein in neurological tissues with multifactorial biological functions. In silico binding prediction analysis revealed the N-terminal leucine-rich repeat (LRR) domain of ANP32A as a significant binding site for synthetic CDR1, which was previously reported as an important docking site for protein-protein interactions (PPI). In accordance with these findings, quantitative proteomic analysis of the retinae ± CDR1 treatment resulted in the identification of 25 protein markers, which were significantly differentially distributed between both experimental groups (CTRL and CDR1, p < 0.05). Particularly, acetyl-CoA biosynthesis I-related enzymes (e.g., DLAT and PDHA1), as well as cytoskeleton-regulating proteins (e.g., MSN), were highly expressed by synthetic CDR1 treatment in the retina; on the contrary, direct ANP32A-interacting proteins (e.g., NME1 and PPP2R4), as well as neurodegenerative-related markers (e.g., CEND1), were identified with significant lower abundancy in the CDR1-treated retinae compared to CTRL. Furthermore, retinal protein phosphorylation and histone acetylation were also affected by synthetic CDR1, which are both partially controlled by ANP32A. In conclusion, the synthetic CDR1 peptide provides a great translational potential for the treatment of glaucoma in the future by eliciting its neuroprotective mechanism via specific interaction with ANP32A's N terminal LRR domain.

Sevoflurane inhibits histone acetylation and contributes to cognitive dysfunction by enhancing the expression of ANP32A in aging mice

Postoperative cognitive dysfunction (POCD) is a major clinical complication after surgery under general anesthesia, particularly in elderly patients, but the mechanisms remain unclear. We recently found that the anaesthetization of aging C57BL/6 J mice (14–16 months) with sevoflurane (3%, two hours each day for three consecutive days) can induce cognitive dysfunction and synaptic plasticity deficits. Further studies demonstrated that sevoflurane induced ANP32A (acidic leucine-rich nuclear phosphoprotein-32A) overexpression by stimulating C/EBPβ (CCAAT/enhancer binding protein-β), which could suppress histone acetylation at H3K18, H3K14, H4K5, and H4K12 and decrease the binding of H3K18 and H3K14 to the promoters of GluN2B and GluN2A, respectively. These results suggest that sevoflurane can inhibit histone acetylation and contribute to cognitive dysfunction by enhancing the expression of ANP32A in aging mice. Our study provides new insights into aging-associated POCD and potential molecular markers for protection.

HYPOXIA AND LOW WNT SIGNALING PROMOTE ANP32A EXPRESSION IN CARTILAGE

Purpose: We previously showed that acidic leucine-rich nuclear phosphoprotein-32A (ANP32A) plays a key protective role in osteoarthritis (OA) by preventing oxidative stress. In OA cartilage, ANP32A is downregulated as compared to non-OA cartilage. Thus, maintaining or increasing ANP32A levels may protect against OA. Yet, factors regulating ANP32A expression remain unknown. Here, we aim to uncover these regulators in order to identify mechanisms that can be targeted to promote ANP32A expression in the articular cartilage.

Behavioral sensitization induced by methamphetamine causes differential alterations in gene expression and histone acetylation of the prefrontal cortex in rats

BackgroundMethamphetamine (METH) is one of the most widely abused illicit substances worldwide; unfortunately, its addiction mechanism remains unclear. Based on accumulating evidence, changes in gene expression and chromatin modifications might be related to the persistent effects of METH on the brain. In the present study, we took advantage of METH-induced behavioral sensitization as an animal model that reflects some aspects of drug addiction and examined the changes in gene expression and histone acetylation in the prefrontal cortex (PFC) of adult rats.MethodsWe conducted mRNA microarray and chromatin immunoprecipitation (ChIP) coupled to DNA microarray (ChIP-chip) analyses to screen and identify changes in transcript levels and histone acetylation patterns. Functional enrichment analyses, including Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, were performed to analyze the differentially expressed genes. We then further identified alterations in ANP32A (acidic leucine-rich nuclear phosphoprotein-32A) and POU3F2 (POU domain, class 3, transcription factor 2) using qPCR and ChIP-PCR assays.ResultsIn the rat model of METH-induced behavioral sensitization, METH challenge caused 275 differentially expressed genes and a number of hyperacetylated genes (821 genes with H3 acetylation and 10 genes with H4 acetylation). Based on mRNA microarray and GO and KEGG enrichment analyses, 24 genes may be involved in METH-induced behavioral sensitization, and 7 genes were confirmed using qPCR. We further examined the alterations in the levels of the ANP32A and POU3F2 transcripts and histone acetylation at different periods of METH-induced behavioral sensitization. H4 hyperacetylation contributed to the increased levels of ANP32A mRNA and H3/H4 hyperacetylation contributed to the increased levels of POU3F2 mRNA induced by METH challenge-induced behavioral sensitization, but not by acute METH exposure.ConclusionsThe present results revealed alterations in transcription and histone acetylation in the rat PFC by METH exposure and provided evidence that modifications of histone acetylation contributed to the alterations in gene expression caused by METH-induced behavioral sensitization.

Identifying factors that regulate ANP32A expression using a novel bioinformatic analysis pipeline

Purpose: Osteoarthritis (OA) is the most common chronic joint disease and is a leading cause of disability. It has a complex pathogeny and causes damage to the articular cartilage, increased joint-associated bone remodelling, and synovial inflammation. Currently, no cure exists and the molecular mechanisms maintaining cartilage homeostasis remain incompletely defined. Previously, an association between polymorphisms in the acidic leucine-rich nuclear phosphoprotein-32A (ANP32A) gene and OA was described. Then, our group showed that ANP32A plays a key protective role in OA by preventing oxidative stress via increasing the transcription of the ATM kinase. Also, we demonstrated that ANP32A is downregulated in OA cartilage as compared to non-OA cartilage. Therefore, maintaining the levels of ANP32A seems to be of crucial importance to preserve joint health and prevent the development and progression of OA. Yet the factors that regulate ANP32A in the joint remain unknown. In this study, we aim to investigate factors that regulate ANP32A expression since such knowledge may lead to the identification of specific novel targets for OA therapy. Methods: An in-house developed bioinformatic pipeline was used in which four bioinformatic tools (BindDB, CONSITE, PROMO and TFsitescan) were interrogated for regulatory factors that are predicted to interact with the ANP32A promotor. The sequence of the ANP32A promotor was obtained using the Eukaryotic Promotor Database (EPD). The Results from these four tools were assembled and then corrected for occurring synonyms. After this, we selected hits that were predicted by two or more databases. An in silico specificity analysis was performed to identify genes with predicted specificity for ANP32A regulation. In this analysis, we excluded hits that also seemed to modulate genes that characterize the chondrocyte identity, namely Aggrecan and Collagen2a1, as well as hits modulating the housekeeping gene Actin. Afterwards, network analysis using StringDB and Humanbase tools was performed, as well as pathway enrichment analysis using the Ingenuity Pathway Analysis (IPA) software. Results: We retrieved 209 hits that were predicted to interact with the ANP32A promoter in silico, of which 49 hits were simultaneously predicted by at least two different bioinformatic tools. After applying the specificity analysis, 16 hits were retained. Network analysis suggested several interesting pathways that may potentially modulate the expression of ANP32A. First, Wnt signaling appeared in the analysis using both the StringDB tool and the IPA software for the 49 hits. Of note, two Wnt signaling TCF/LEF transcription factors were present among the 16 final hits obtained after applying the specificity analysis. Wnt hyper-activation is known to contribute to OA and targeting this pathway is becoming increasingly interesting in the treatment of OA. Second, the network analysis indicated the hypoxia pathway as a potential regulator for ANP32A expression. This pathway is noteworthy since the oxygen gradients in OA cartilage are known to be disturbed. Lastly, network analysis further pointed out cellular senescence (StringDB tool and IPA analysis) and histone modifications (StringDB tool) among the enriched pathways. Both the senescence pathway and alterations in histone modifications have been linked to OA. Conclusions: The bioinformatic pipeline suggested 16 potential regulatory factors for ANP32A expression. Combined with the network analysis, we identified Wnt signaling, hypoxia, cellular senescence and histone modifications as potential regulatory networks for ANP32A transcription. In our future experiments, we will further investigate the significance of these in silico findings and their potential clinical implications in OA.

ANP32A promotes the proliferation, migration and invasion of hepatocellular carcinoma by modulating the HMGA1/STAT3 pathway.

Acidic leucine-rich nuclear phosphoprotein-32A (ANP32A) has been reported to play an essential role in the development and progression of various human cancers. However, its expression pattern and possible mechanism in human hepatocellular carcinoma (HCC) remain to be elucidated. In this study, we used western blot and immunohistochemical staining to detect protein expression. The effects of ANP32A on the proliferation, migration and invasion of HCC cells were examined using 5-ethynyl-20-deoxyuridine (EdU), colony formation, CCK-8, and transwell assays. RT-qPCR was performed to detect mRNA expression. The interaction between ANP32A and the high mobility group A1 (HMGA1) mRNA was assessed using RNA immunoprecipitation (RIP). The tumorigenicity of ANP32A was assessed by establishing a xenograft tumor model in Balb/c nude mice. We found that the ANP32A protein was expressed at high levels in patients with HCC, which was associated with a poor prognosis. Functional experiments revealed that the silencing of ANP32A inhibited the proliferation, migration, and invasion of HCC cells, whereas overexpression of ANP32A promoted these processes. Further investigations indicated that ANP32A bound the HMGA1 mRNA and maintained its stability to promote the expression of HMGA1, thereby increasing the expression and activation of STAT3. Finally, a xenograft tumor model of Balb/c nude mice confirmed the tumorigenicity of ANP32A. This study found that ANP32A is up-regulated in patients with HCC and may accelerate the proliferation, migration and invasion of HCC cells by modulating the HMGA1/STAT3 pathway.

ANP32A is a hub molecule regulating a protective network against osteoarthritis

Purpose: Osteoarthritis (OA), the most common joint disease for which no effective therapy currently exists, has a complex pathogeny with diverse interacting factors causing articular cartilage damage and alterations in other joint tissues. We previously described an association between polymorphisms in the acidic leucine-rich nuclear phosphoprotein-32A (ANP32A) gene and OA. Recently, we discovered that ANP32A protects against OA by promoting expression of antioxidant enzyme ATM in cartilage, thereby reducing oxidative stress.

Acidic leucine-rich nuclear phosphoprotein-32A expression contributes to adverse outcome in acute myeloid leukemia

BackgroundAcidic leucine-rich nuclear phosphoprotein-32A (ANP32A) is a novel regulator of histone H3 acetylation and promotes leukemogenesis in acute myeloid leukemia (AML). However, its prognostic value in AML remains unclear.MethodsIn this study, we evaluated the prognostic significance of ANP32A expression using two independent large cohorts of cytogenetically normal AML (CN-AML) patients. Multivariable analysis in CN-AML group was also presented. Based on the ANP32A expression, its related genes, dysregulation of pathways, interaction network analysis between microRNAs and target genes, as well as methylation analysis were performed to unveil the complex functions behind ANP32A.ResultsHere we demonstrated overexpression of ANP32A was notably associated with unfavorable outcome in two independent cohorts of CN-AML patients (OS: P=0.012, EFS: P=0.005, n=185; OS: P=0.041, n=232), as well as in European Leukemia Net (ELN) Intermediate-I group (OS: P=0.018, EFS: P=0.045, n=115), National Comprehensive Cancer Network (NCCN) Intermediate Risk AML group (OS: P=0.048, EFS: P=0.039, n=225), and non-M3 AML group (OS: P=0.034, EFS: P=0.011, n=435). Multivariable analysis further validated ANP32A as a high-risk factor in CN-AML group. Multi-omics analysis presented overexpression of ANP32A was associated with aberrant expression of oncogenes and tumor suppressor, up/down-regulation of metabolic and immune-related pathways, dysregulation of microRNAs, and hypomethylation on CpG island and 1st Exon regions.ConclusionsWe proved ANP32A as a novel, potential unfavorable prognosticator and therapeutic target for AML.

PHAP1 promotes glioma cell proliferation by regulating the Akt/p27/stathmin pathway.

PHAP1 (Putative HLA‐DR‐associated protein 1), also termed acidic leucine‐rich nuclear phosphoprotein 32A (ANP32A), Phosphoprotein 32 (pp32) or protein phosphatase 2A inhibitor (I1PP2A), is a multifunctional protein aberrantly expressed in multiple types of human cancers. However, its expression pattern and clinical relevance in human glioma remain unknown. In this study, Western blotting and immunohistochemistry analysis demonstrated PHAP1 protein was highly expressed in glioma patients, especially in those with high‐grade disease. Publicly available data also revealed high levels of PHAP1 were associated with poor prognosis in glioma patients. The functional studies showed that knock‐down of PHAP1 suppressed the proliferation of glioma cells, while overexpression of PHAP1 facilitated it. The iTRAQ proteomic analysis suggested that stathmin might be a potential downstream target of PHAP1. Consistently, PHAP1 knock‐down significantly decreased the expression of stathmin, while overexpression of PHAP1 increased it. Also, the upstream negative regulator, p27, expression levels increased upon PHAP1 knock‐down and decreased when PHAP1 was overexpressed. As a result, the phosphorylated Akt (S473), an upstream regulator of p27, expression levels decreased upon silencing of PHAP1, but elevated after PHAP1 overexpression. Importantly, we demonstrate the p27 down‐regulation, stathmin up‐regulation and cell proliferation acceleration induced by PHAP1 overexpression were dependent on Akt activation. In conclusion, the above results suggest that PHAP1 expression is elevated in glioma patients, which may accelerate the proliferation of glioma cells by regulating the Akt/p27/stathmin pathway.

ANP32A regulates histone H3 acetylation and promotes leukemogenesis.

Deregulation of key regulators of histone modification is important in the initiation and progression of human leukemia. Acidic leucine-rich nuclear phosphoprotein-32A (ANP32A) participates in histone acetylation and its role in acute myeloid leukemia remains unclear. Here we observed significant upregulation of ANP32A in primary AML cells, which was essential for AML cell proliferation, survival, and colony formation. Integrative analysis of the genome-wide histone H3 acetylation and gene expression demonstrated that ANP32A deficiency reduced histone H3 acetylation, in accordance with changes in gene expression. Notably, significant histone H3 acetylation enrichment was associated with mRNA changes in lipid-related genes, including APOC1, PCSK9, P2RX1, and LPPR3. Indeed, over-expression of APOC1 partially compensated the proliferation-defect phenotype in ANP32A deficient AML cells while APOC1 knockdown alone mimicked the effect of ANP32A deficiency. Collectively, our data indicate that ANP32A is a novel regulator of histone H3 acetylation and promotes leukemogenesis.

ANP32A modulates cell growth by regulating p38 and Akt activity in colorectal cancer

Acidic leucine-rich nuclear phosphoprotein-32A (ANP32A) possesses multiple biochemical activities, has been found to be decreased or absent in malignant tumors. However, new findings have shown that it is expressed in greater amounts in advanced cancers than in early-stage tumors. The role and clinical significance of ANP32A in colorectal cancer (CRC) is still unknown. In the present study, the expression of ANP32A was assessed in 68CRC patients by IHC, and then the correlation of its expression with clinicopathological factors was investigated using the Allred, Klein and immune response scoring system analysis. Western blot and real-time PCR analyses were used to assess ANP32A expression and the activity of Akt and p38 in cancer and normal tissues. These data indicated a significant association between ANP32A expression and the activity of Akt and p38, besides the tumor differentiation status in CRC patients. IHC and western blotting data revealed that ANP32A was overexpressed in CRC patients, and ANP32A levels were higher in poorly differentiated tumors. Protein and mRNA analysis revealed that with a high expression of ANP32A, the activation of Akt was enhanced, while the p-38 phosphorylation level was decreased in CRC tissues. MTT assay and functional studies revealed that knockdown of ANP32A inhibited cell growth and induced p38 phosphorylation and Akt dephosphorylation. The present study indicated that ANP32A promoted CRC proliferation by inhibition of p38 and activation of Akt signaling pathways and suggested that ANP32A may play a potential role in CRC diagnosis and therapy.

ANP32A Regulates Histone 3 Acetylation and Promotes Leukemogenesis in AML

Leukemia initiation and progression not only depend on genetic alterations but also on abnormal epigenetic changes that cause disorder of gene expression. Acidic leucine-rich nuclear phosphoprotein-32A (ANP32A) binds directly to histone tails, preferentially to unmodified histone H3 tails (Schneider et al., 2004; Seo et al., 2002). Although ANP32A inhibits histone acetyltransferase activity in vitro (Seo et al., 2002), loss of ANP32A leads to decreased histone 3 acetylation (acetyl-H3) levels on interferon-stimulated genes in human cervical carcinoma HeLa S3 cells (Kadota et al., 2011). Aberrant ANP32A expression has been observed in many solid tumors, which involves in diverse processes depending on the cell context (Brody et al., 2004; Hoffarth et al., 2008), yet mechanisms are still unknown. Furthermore, there has as yet been no specific investigation into the role of ANP32A in acute myeloid leukemia (AML).We found that ANP32A expression was upregulated at both mRNA and protein levels in patients with AML. In AML primary cells from patients, ANP32A KD decreased cell proliferation and colony formation ability. In addition, ANP32A KD induced apoptosis and cell cycle arrest at G1 phase accompanied with the downregulated protein expression of survival or cell cycle progress genes BCL2, CDK4, CCND1 and the upregulated protein expression of pro-apoptosis genes BAK, BAD, cleaved caspase 3. These findings were also verified in various subtypes of AML cell lines and Mll-Af9 pre-leukemic cells. Thus, ANP32A is essential for cell growth via the promotion of cell-cycle progression and inhibition of apoptosis in AML.Given that ANP32A associates with histone acetylation modification, we analyzed the effect of ANP32A depletion on acetyl-H3 and histone 4 acetylation (acetyl-H4). Western blot analysis showed that ANP32A KD caused global decrease of acetyl-H3, but no effect on the global level of acetyl-H4. To investigate the mechanism of ANP32A in AML, ChIP-seq and gene expression microarray experiments were performed to determine acetyl-H3 enrichment and transcriptome profiles, respectively, in ANP32A KD and control K562 cells. We found a positive correlation between changes in gene expression and changes in acetyl-H3 (r=0.16, p<10-4), especially for differential expression genes (DEGs; r=0.40, p<10-4). Moreover, we also found genes with decreased acetyl-H3 enrichment displayed lower expression levels compared with genes with increased acetyl-H3 enrichment (p<10-3). Thus, ANP32A alters acetyl-H3 modification in association with changes in gene expression.Gene set enrichment analysis (GSEA) revealed that ANP32A KD significantly decreased the acetyl-H3 enrichment levels at genes of lipid metabolism signatures (e.g. lipid metabolic process, cholesterol homeostasis). Transcriptome profile analysis using GSEA showed that gene expression levels of lipid metabolic process signature were also reduced after ANP32A KD. We further identified 4 genes (APOC1, CNKSR3, H19, PCSK9) which had significantly lower levels of mRNA expression (p<10-2, FDR<10-2, FC>1.5) and decreased levels of acetyl-H3 enrichment (p<10-2, FDR<10-2, FC>1.5) in ANP32A KD cells. Apolipoprotein CI(APOC1) was the most significantly downregulated gene among these 4 genes, with decreased acetyl-H3 on its promoter. To explore whether lipid metabolism as a downstream effector of ANP32A contributes to ANP32A function in AML, re-introduction of APOC1 was performed in ANP32A KD THP1 or K562 cells. Re-introduction of APOC1 significantly rescued the inhibition of cell growth in ANP32A KD AML cells, also upregulated protein expression of BCL2, CDK4 and CCND1, showing that ANP32A functions in AML partially depending on APOC1. Importantly, APOC1 depletion decreased cell proliferation of AML cells in vitro, consistent with the point of view that complex lipid alterations contribute to endoplasmic reticulum stress-induced apoptosis in cancer cells (Beloribi-Djefaflia et al., 2016; Iurlaro et al., 2016).Overall, our data suggest ANP32A as a novel regulator of leukemogenesis in AML. ANP32A may involve in the regulation of genome-wide histone 3 acetylation that alters the expression of multiple genes, including lipid metabolism related gene APOC1. Thus, ANP32A is a promising drug target for AML therapy. DisclosuresNo relevant conflicts of interest to declare.

Acidic leucine-rich nuclear phosphoprotein-32A (ANP32A) association with lymph node metastasis predicts poor survival in oral squamous cell carcinoma patients.

Acidic leucine-rich nuclear phosphoprotein-32A (ANP32A) is a multifunctional protein aberrantly expressed in various types of cancers. However, its expression pattern and clinical significance in oral squamous cell carcinoma (OSCC) remains unclear. In this study, we immunohistochemically investigated the expression pattern of ANP32A in 259 OSCC patients and the results were correlated with clinicopathological factors using Allred, Klein and Immunoreactive scoring (IRS) system. Our data indicated that high expression of ANP32A was significantly associated with N stage and tumor differentiation status in OSCC patients. High ANP32A expression with N2/N3 stage had an increased mortality risk than low ANP32A expressing OSCC patients with N0/N1 stage. Functional studies revealed that knockdown of ANP32A significantly decreased the migration and invasion ability thereby concomitantly increasing E-cadherin and decreasing Slug, Claudin-1 and Vimentin expression in vitro. These results suggest that ANP32A is commonly increased in oral squamous cell carcinoma and ANP32A protein could act as a potential biomarker for prognosis assessment of oral cancer patients with lymph node metastasis.

High-resolution crystal structure of the leucine-rich repeat domain of the human tumour suppressor PP32A (ANP32A).

Acidic leucine-rich nuclear phosphoprotein 32A (PP32A) is a tumour suppressor whose expression is altered in many cancers. It is an apoptotic enhancer that stimulates apoptosome-mediated caspase activation and also forms part of a complex involved in caspase-independent apoptosis (the SET complex). Crystals of a fragment of human PP32A corresponding to the leucine-rich repeat domain, a widespread motif suitable for protein-protein interactions, have been obtained. The structure has been refined to 1.56 Å resolution. This domain was previously solved at 2.4 and 2.69 Å resolution (PDB entries 2je0 and 2je1, respectively). The new high-resolution structure shows some differences from previous models: there is a small displacement in the turn connecting the first α-helix (α1) to the first β-strand (β1), which slightly changes the position of α1 in the structure. The shift in the turn is observed in the context of a new crystal packing unrelated to those of previous structures.

Sphingosine Interaction with Acidic Leucine-rich Nuclear Phosphoprotein-32A (ANP32A) Regulates PP2A Activity and Cyclooxygenase (COX)-2 Expression in Human Endothelial Cells

Sphingolipid metabolites regulate cell fate by acting on specific cellular targets. Although the influence of sphingolipids in cellular signaling has been well recognized, the exact molecular targets and how these targets influence cellular signaling mechanisms remain poorly understood. Toward this goal, we used affinity chromatography coupled with proteomics technology and identified acidic leucine-rich nuclear phosphoprotein-32A (ANP32A), an inhibitor of protein phosphatase 2A (PP2A) as a direct target of sphingosine, N,N'-dimethyl sphingosine (DMS) and phytosphingosine but not dihydrosphingosine or sphingosine 1-phosphate. Treatment of human umbilical vein endothelial cells (HUVEC) with DMS, which is not phosphorylated by sphingosine kinases, led to the activation of PP2A activity. Suppression of ANP32A with siRNA enhanced basal and DMS-activated PP2A activity suggesting that the sphingoid base binds to and relieves the inhibitory action of ANP32A on the PP2A complex. Indeed, DMS relieved the ANP32A-mediated inhibition of PP2A enzyme complex in vitro. Interestingly, DMS treatment induced the p38 stress-activated protein kinase (SAPK) and expression of cyclooxygenase (COX)-2 transcript and protein. Knockdown of ANP32A expression further induced p38 SAPK and COX-2. These data identify ANP32A as a novel molecular target of sphingoid bases that regulates cellular signaling events and inflammatory gene expression.