Human CPPED1 belongs to calcineurin-like metallophosphoesterase superfamily and dephosphorylates PI3K-AKT pathway component PAK4

CircCDK1 blocking IGF2BP2-mediated m6A modification of CPPED1 promotes laryngeal squamous cell carcinoma metastasis via the PI3K/AKT signal pathway

BACKGROUND

Circular RNA (circRNA) is a novel noncoding RNA (ncRNA) that plays a critical role in various cancers. However, the clinical significance, biological function, and molecular mechanisms of circRNAs in laryngeal squamous cell carcinoma (LSCC) remain unclear.

METHODS

A circRNA array was performed to identify the differentially expressed circRNAs. In vitro and in vivo assays were proceeded to verify the biological function of circCDK1 in LSCC. RNA pulldown assays and RNA immunoprecipitation (RIP) were used to confirm the binding between circCDK1 and insulin-like growth factor 2 mRNA binding protein 2(IGF2BP2). The MeRIP assay was then used to identified the N6-methyladenisine (m6A) methylation of calcineurin like phosphatase domain containing1 (CPPED1).

RESULTS

Hsa_circ_0005774 (circCDK1) was found upregulated in LSCC tissues compared to adjacent normal tissues. The level of circCDK1 was positively correlated with poor prognosisof LSCC patients. In vitro and in vivo, circCDK1 promoted migration and invasion of LSCC cells. Mechanistically, eukaryotic translation initiation factor4A3(EIF4A3) induced biogenesis of circCDK1 by binding to its flanking. By competitively binding to IGF2BP2, circCDK1 blocked the m6A modification of CPPED1 in IGF2BP2-dependent manner. Moreover, the circCDK1-mediated decrease of CPPED1 activated the PI3K/AKT signal pathway to facilitate progression of LSCC.

CONCLUSIONS

Our findings demonstrated that EIF4A3-induced upregulation of circCDK1 promoted LSCC metastasis via EIF4A3-circCDK1-IGF2BP2-CPPED1 to activate PI3K-AKT signal pathway. CircCDK1 might serve as a new diagnostic and prognostic marker or potential therapeutic target for LSCC.

The potential function of SP1 and CPPED1 in restenosis after percutaneous coronary intervention

OBJECTIVES

Impacts of molecular pathways have been discussed recently on restenosis after percutaneous coronary intervention (PCI). Hence, this study aimed to explore the impact of calcineurin-like phosphoesterase domain containing 1 (CPPED1) and specificity protein 1 (SP1) on restenosis after PCI.

METHODS

A carotid balloon injury rat model was established, followed by western blot analysis of SP1 and CPPED1 expression in carotid artery (CA) tissues. After SP1 and CPPED1 were overexpressed, the neointimal hyperplasia and luminal stenosis were assessed. In addition, EPC underwent hypoxia/reoxygenation (H/R) treatment to construct an endothelial injury cell model. Then, cell proliferation, apoptosis, intracellular reactive oxygen species (ROS), and Ca²⁺ concentration were detected with cell counting kit-8 (CCK-8), flow cytometry, Chloromethyl-2'7'-dichlorofluorescein diacetate (CM-H2DCFDA) penetrant, and Fluo-4 AM staining, respectively. The binding relationship between SP1 and CPPED1 was verified by dual-luciferase reporter and chromatin immunoprecipitation (ChIP) assays.

RESULTS

SP1 and CPPED1 were lowly expressed in the model rats with carotid balloon injury. Mechanistically, SP1 bound to the promoter region of CPPED1 to activate CPPED1 expression. Overexpressing SP1 or CPPED1 lowered neointimal formation and restenosis rate, thus promoting the recovery of carotid balloon injury in rats. Meanwhile, SP1 and CPPED1 upregulation reduced ROS levels, Ca²⁺ concentration, and apoptosis of EPCs, accompanied by accelerated EPC viability.

CONCLUSIONS

SP1 or CPPED1 overexpression reduced neointimal formation and restenosis rate in carotid balloon injury.

SPTBN1 attenuates rheumatoid arthritis synovial cell proliferation, invasion, migration and inflammatory response by binding to PIK3R2

BACKGROUND

As an autoimmune systemic disorder, rheumatoid arthritis (RA) features chronic inflammation as well as synovial infiltration of immune cells. This study was designed with the purpose of discussing the hidden mechanism of SPTBN1 and exploring favorable molecular-targeted therapies.

METHODS

With the application of RT-qPCR and western blot, the expressions of SPTBN1 and PIK3R2 before or after transfection were estimated. Besides, Cell Counting Kit-8, Edu, wound healing, transwell, enzyme-linked immunosorbent assay, and TUNEL were adopted for the evaluation of the viability, proliferation, migration, invasion, inflammatory response, and apoptosis of fibroblast-like synoviocyte (FLS). In addition, the interaction of SPTBN1 and PIK3R2 was testified by applying immunoprecipitation (IP) and western blot was utilized for the assessment of migration-, apoptosis-, and PI3K/AKT signal-related proteins.

RESULTS

It was discovered that SPTBN1 declined in RA synovial cells and its overexpression repressed the proliferation, migration, invasion, and inflammation of RA-FLSs but promoted apoptosis. IP confirmed that SPTBN1 could bind to PIK3R2 in FLSs. To further figure out the hidden mechanism of SPTBN1 in RA, a series of functional experiments were carried out and the results demonstrated that the reduced expressions of MMP2, MMP9, IL-8, IL-1β, IL-6, and Bcl2 as well as increased levels of Bax and cleaved caspase3 in SPTBN1-overexpressed RA-FLSs were reversed by PIK3R2 depletion, revealing that SPTBN1 repressed the migration and inflammation and promoted the apoptosis of RA-FLSs via binding to PIK3R2. Results obtained from western blot also revealed that PIK3R2 interference ascended the contents of p-PI3K and p-AKT in SPTBN1-overexpressed RA-FLSs, implying that SPTBN1 repressed PI3K/AKT signal in RA via PIK3R2.

DISCUSSION

SPTBN1 alleviated the proliferation, migration, invasion, and inflammation in RA via interacting with PIK3R2.

A single-cell analysis of thymopoiesis and thymic iNKT cell development in pigs

Many aspects of the porcine immune system remain poorly characterized, which poses a barrier to improving swine health and utilizing pigs as preclinical models. Here, we employ single-cell RNA sequencing (scRNA-seq) to create a cell atlas of the early-adolescent pig thymus. Our data show conserved features as well as species-specific differences in cell states and cell types compared with human thymocytes. We also describe several unconventional T cell types with gene expression profiles associated with innate effector functions. This includes a cell census of more than 11,000 differentiating invariant natural killer T (iNKT) cells, which reveals that the functional diversity of pig iNKT cells differs substantially from the iNKT0/1/2/17 subset differentiation paradigm established in mice. Our data characterize key differentiation events in porcine thymopoiesis and iNKT cell maturation and provide important insights into pig T cell development.

Human placental proteomics and exon variant studies link AAT/SERPINA1 with spontaneous preterm birth

BACKGROUND

Preterm birth is defined as live birth before 37 completed weeks of pregnancy, and it is a major problem worldwide. The molecular mechanisms that lead to onset of spontaneous preterm birth are incompletely understood. Prediction and evaluation of the risk of preterm birth is challenging as there is a lack of accurate biomarkers. In this study, our aim was to identify placental proteins that associate with spontaneous preterm birth.

METHODS

We analyzed the proteomes from placentas to identify proteins that associate with both gestational age and spontaneous labor. Next, rare and potentially damaging gene variants of the identified protein candidates were sought for from our whole exome sequencing data. Further experiments we performed on placental samples and placenta-associated cells to explore the location and function of the spontaneous preterm labor-associated proteins in placentas.

RESULTS

Exome sequencing data revealed rare damaging variants in SERPINA1 in families with recurrent spontaneous preterm deliveries. Protein and mRNA levels of alpha-1 antitrypsin/SERPINA1 from the maternal side of the placenta were downregulated in spontaneous preterm births. Alpha-1 antitrypsin was expressed by villous trophoblasts in the placenta, and immunoelectron microscopy showed localization in decidual fibrinoid deposits in association with specific extracellular proteins. siRNA knockdown in trophoblast-derived HTR8/SVneo cells revealed that SERPINA1 had a marked effect on regulation of the actin cytoskeleton pathway, Slit-Robo signaling, and extracellular matrix organization.

CONCLUSIONS

Alpha-1 antitrypsin is a protease inhibitor. We propose that loss of the protease inhibition effects of alpha-1 antitrypsin renders structures critical to maintaining pregnancy susceptible to proteases and inflammatory activation. This may lead to spontaneous premature birth.

Human CPPED1 belongs to calcineurin-like metallophosphoesterase superfamily and dephosphorylates PI3K-AKT pathway component PAK4

Protein kinases and phosphatases regulate cellular processes by reversible phosphorylation and dephosphorylation events. CPPED1 is a recently identified serine/threonine protein phosphatase that dephosphorylates AKT1 of the PI3K-AKT signalling pathway. We previously showed that CPPED1 levels are down-regulated in the human placenta during spontaneous term birth. In this study, based on sequence comparisons, we propose that CPPED1 is a member of the class III phosphodiesterase (PDE) subfamily within the calcineurin-like metallophosphoesterase (MPE) superfamily rather than a member of the phosphoprotein phosphatase (PPP) or metal-dependent protein phosphatase (PPM) protein families. We used a human proteome microarray to identify 36 proteins that putatively interact with CPPED1. Of these, GRB2, PAK4 and PIK3R2 are known to regulate the PI3K-AKT pathway. We further confirmed CPPED1 interactions with PAK4 and PIK3R2 by coimmunoprecipitation analyses. We characterized the effect of CPPED1 on phosphorylation of PAK4 and PIK3R2 in vitro by mass spectrometry. CPPED1 dephosphorylated specific serine residues in PAK4, while phosphorylation levels in PIK3R2 remained unchanged. Our findings indicate that CPPED1 may regulate PI3K-AKT pathway activity at multiple levels. Higher CPPED1 levels may inhibit PI3K-AKT pathway maintaining pregnancy. Consequences of decreased CPPED1 expression during labour remain to be elucidated.