Protein Phosphatase Research Articles

PP2Ac Regulates Autophagy via Mediating mTORC1 and ULK1 During Osteoclastogenesis in the Subchondral Bone of Osteoarthritis.

The molecular mechanism underlying abnormal osteoclastogenesis triggering subchondral bone remodeling in osteoarthritis (OA) is still unclear. Here, single-cell and bulk transcriptomics sequencing analyses are performed on GEO datasets to identify key molecules and validate them using knee joint tissues from OA patients and rat OA models. It is found that the catalytic subunit of protein phosphatase 2A (PP2Ac) is highly expressed during osteoclastogenesis in the early stage of OA and is correlated with autophagy. Knockdown or inhibition of PP2Ac weakened autophagy during osteoclastogenesis. Furthermore, the ULK1 expression of the downstream genes is significantly increased when PP2Ac is knocked down. PP2Ac-mediated autophagy is dependent on ULK1 phosphorylation activity during osteoclastogenesis, which is associated with enhanced dephosphorylation of ULK1 Ser637 residue regulating at the post-translational level. Additionally, mTORC1 inhibition facilitated the expression level of PP2Ac during osteoclastogenesis. In animal OA models, decreasing the expression of PP2Ac ameliorated early OA progression. The findings suggest that PP2Ac is also a promising therapeutic target in early OA.

BCL2 interacting protein 3 as a potential biomarker for Alzheimer’s disease: an observational study

As important organelles for energy production, mitochondria exhibit dysfunction as an early hallmark of Alzheimer’s disease, potentially leading to cell death and impaired brain function. The mitophagy receptors BCL2 interacting protein 3 and BCL2 interacting protein 3 like (NIX), which are regulated by protein phosphatase targeting COQ7 (PPTC7), play crucial roles in controlling the quantity of mitochondria within cells. In this study, we found that the expression level of BCL2 interacting protein 3 was positively correlated with Mini-Mental State Examination scores, indicating that a lower BCL2 interacting protein 3 expression was associated with a higher degree of dementia. Under pathological conditions of Alzheimer’s disease, the expression levels of protein phosphatase targeting COQ7, BCL2 interacting protein 3, and BCL2 interacting protein 3 like were decreased. Overall, BCL2 interacting protein 3 may serve as a potential biomarker of Alzheimer’s disease.

Protein phosphatase PP2Cα S-glutathionylation regulates cell migration

Redox signaling is a fundamental mechanism that controls all major biological processes partly via protein cysteine oxidations, including S-glutathionylation. Despite over 2,000 cysteines identified to form S-glutathionylation in databases, the identification of redox cysteines functionally linked to a biological process of interest remains challenging. Here, we demonstrate a strategy combining glutathionylation proteomic database, bioinformatics, and biological screening, which resulted in the identification of S-glutathionylated proteins, including PP2Cα, as redox players of cell migration. We showed that PP2Cα, a prototypical magnesium-dependent serine/threonine phosphatase, is susceptible to S-glutathionylation selectively at non-conserved C314. PP2Cα glutathionylation causes increased migration and invasion of breast cancer cell lines in oxidative stress or upon hydrogen peroxide production. Mechanistically, PP2Cα glutathionylation modulates its protein-protein interactions, activating c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) pathways to elevate migration and invasion. In addition, PP2Cα glutathionylation occurs in response to epidermal-growth factor, supporting a serine/threonine phosphatase PP2Cα as a new redox player in growth factor signal transduction.

Short-Term Statin Therapy Induces Hepatic Insulin Resistance Through HNF4α/PAQR9/PPM1α Axis Regulated AKT Phosphorylation.

Statins, the first-line medication for dyslipidemia, are linked to an increased risk of type 2 diabetes. But exactly how statins cause diabetes is yet unknown. In this study, a developed short-term statin therapy on hyperlipidemia mice show that hepatic insulin resistance is a cause of statin-induced diabetes. Statin medication raises the expression of progesterone and adiponectin receptor 9 (PAQR9) in liver, which inhibits insulin signaling through degradation of protein phosphatase, Mg2+/Mn2+ dependent 1 (PPM1α) to activate ERK pathway. STIP1 homology and U-box containing protein 1 (STUB1) is found to mediate ubiquitination of PPM1α promoted by PAQR9. On the other hand, decreased activity of hepatocyte nuclear factor 4 alpha (HNF4α) seems to be the cause of PAQR9 expression under statin therapy. The interventions on PAQR9, including deletion of PAQR9, caloric restriction and HNF4α activation, are all effective treatments for statin-induced diabetes, while liver specific over-expression of PPM1α is another possible tactic. The results reveal the importance of HNF4α-PAQR9-STUB1-PPM1α axis in controlling the statin-induced hepatic insulin resistance, offering a fresh insight into the molecular mechanisms underlying statin therapy.

Reversible control of kinase signaling through chemical-induced dephosphorylation

The coordination between kinases and phosphatases is crucial for regulating the phosphorylation levels of essential signaling molecules. Methods enabling precise control of kinase activities are valuable for understanding the kinase functions and for developing targeted therapies. Here, we use the abscisic acid (ABA)-induced proximity system to reversibly control kinase signaling by recruiting phosphatases. Using this method, we found that the oncogenic tyrosine kinase BCR::ABL1 can be inhibited by recruiting various cytoplasmic phosphatases. We also discovered that the oncogenic serine/threonine kinase BRAF(V600E), which has been reported to bypass phosphorylation regulation, can be positively regulated by protein phosphatase 1 (PP1) and negatively regulated by PP5. Additionally, we observed that the dual-specificity kinase MEK1 can be inhibited by recruiting PP5. This suggests that bifunctional molecules capable of recruiting PP5 to MEK or RAF kinases could be promising anticancer drug candidates. Thus, the ABA-induced dephosphorylation method enables rapid screening of phosphatases to precisely control kinase signaling.

The BDNF-ERK/MAPK axis reduces phosphatase and actin regulator1, 2 and 3 (PHACTR1, 2 and 3) mRNA expressions in cortical neurons.

Actin rearrangement and phosphorylation-dephosphorylation in the nervous system contribute to plastic alteration of neuronal structure and function. Phosphatase and actin regulator (PHACTR) family members are actin- and protein phosphatase 1 (PP1)-binding proteins. Because some family members act as regulators of neuronal morphology, studying the regulatory mechanisms of PHACTR is valuable for understanding the basis of neuronal circuit formation. Although expression patterns of PHACTR family molecules (PHACTR1-4) vary across distinct brain areas, little is known about the extracellular ligands that influence their mRNA levels. In this study, we focused on an important neurotrophin, brain-derived neurotrophic factor (BDNF), and examined its effect on mRNA expression of PHACTR family member in cortical neurons. PHACTR1-3, but not PHACTR4, were affected by stimulation of primary cultured cortical neurons with BDNF; namely, sustained downregulation of their mRNA levels was observed. The observed downregulation was blocked by an inhibitor of the extracellular signal-regulated protein kinase/mitogen-activated protein kinase (ERK/MAPK) pathway, U0126, suggesting that ERK/MAPK plays an inhibitory role for gene induction of PHACTR1-3. These findings aid the elucidation of how BDNF regulates actin- and PP1-related neuronal functions.

Cantharidin and sodium fluoride attenuate the negative inotropic effect of the A1-adenosine receptor agonist N6-(R)-phenylisopropyl adenosine in isolated human atria.

Cantharidin and sodium fluoride inhibit the activity of serine/threonine protein phosphatases 1 (PP1) and 2A (PP2A) and increase the force of contraction in human atrial preparations. R-phenylisopropyl adenosine (R-PIA) acts as an agonist at A1-adenosine receptors. R-PIA exerts a negative inotropic effect on human atria. The effect of R-PIA-and its various manifestations-are currently explained as a function of the inhibition of sarcolemmal adenylyl cyclase activity and/or opening of sarcolemmal potassium channels. We hypothesise that cantharidin and sodium fluoride may attenuate the negative inotropic effect of R-PIA. During open heart surgery, trabeculae carneae from the right atrium were obtained for human atrial preparations (HAPs). These trabeculae were mounted in organ baths and electrically stimulated at 1Hz. Furthermore, we studied isolated electrically stimulated left atrial (LA) preparations from female wild-type mice (CD1). The force of contraction was recorded under isometric conditions. R-PIA (1µM) exerted a rapid negative inotropic effect in the HAPs and mice LA preparations. These negative inotropic effects of R-PIA were attenuated by pre-incubation for 30min with 100-µM cantharidin in HAPs, but not in mice LA preparations. Adenosine signals via A1 receptors in a species-specific pathway in mammalian atria. We postulate that R-PIA, at least in part, exerts a negative inotropic effect via activation of serine/threonine phosphatases in the human atrium.

PPP1R14B-mediated phosphorylation enhances protein stability of RPS6KA1 to promote hepatocellular carcinoma tumorigenesis

Hepatocellular carcinoma (HCC) is one of the most prevalent cancers worldwide with a poor clinical prognosis. Protein phosphatase 1 regulatory subunit 14B (PPP1R14B) is an unidentified protein phosphatase 1 regulatory subunit that is associated with the occurrence and development of various cancers. Recently, PPP1R14B was found to contribute to paclitaxel resistance and cell progression in triple-negative breast cancer; however, the role of PPP1R14B in HCC is unknown. Here, we found that PPP1R14B was highly expressed in HCC tissues, which suggested a poor prognosis. Knockdown of PPP1R14B significantly inhibited the survival and tumorigenic ability of HCC cells, while overexpression of PPP1R14B had the opposite effects. Mechanistically, Ribosomal Protein S6 Kinase type 1(RPS6KA1) was identified as the target gene of PPP1R14B. PPP1R14B maintained the stability and phosphorylation of RPS6KA1, and positively regulated activation of the AKT/NF-κB pathway. Importantly, PPP1R14B-deficient tumor suppression could be partially restored by wild-type but not phosphorylated mutant RPS6KA1. Taken together, these findings shed light on the function and mechanism of PPP1R14B in HCC progression, indicating PPP1R14B is a promising molecular target for the treatment of HCC.

DUSP5 deficiency suppresses the progression of acute kidney injury by enhancing autophagy through AMPK/ULK1 pathway

Acute kidney injury (AKI) represents a critical clinical disease characterized by the rapid decline in renal function, carrying a substantial burden of morbidity and mortality. The treatment of AKI is frequently limited by its variable clinical presentations and intricate pathophysiology, highlighting the urgent need for a deeper understanding of its pathogenesis and potential therapeutic targets. Dual-specific protein phosphatase 5 (DUSP5), a member of the serine-threonine phosphatase family, possesses the capability to dephosphorylate extracellular regulated protein kinases (ERK). DUSP5 has emerged as a pivotal player in modulating metabolic signals, inflammatory responses, and cancer progression, while also being closely associated with various kidney diseases. This study systematically scrutinized the function and mechanism of DUSP5 in AKI for the first time, unveiling a substantial increase in DUSP5 expression during AKI. Moreover, DUSP5 knockdown was observed to attenuate the production of inflammatory factors and apoptotic cells in renal tubular epithelial cells by enhancing AMPK/ULK1-mediated autophagy, thus improving renal function. In a word, DUSP5 knockdown in AKI effectively impede disease progression by activating autophagy. This finding holds promise for introducing fresh perspectives and targets for AKI treatment.

Alternating binding and p97-mediated dissociation of SDS22 and I3 recycles active PP1 between holophosphatases

Protein phosphatase-1 catalytic subunit (PP1) joins diverse targeting subunits to form holophosphatases that regulate many cellular processes. Newly synthesized PP1 is known to be transiently sequestered in an inhibitory complex with Suppressor-of-Dis2-number-2 (SDS22) and Inhibitor-3 (I3), which is disassembled by the ATPases Associated with diverse cellular Activities plus (AAA+) protein p97. Here, we show that the SDS22-PP1-I3 complex also acts as a thermodynamic sink for mature PP1 and that cycles of SDS22-PP1-I3 formation and p97-driven disassembly regulate PP1 function and subunit exchange beyond PP1 biogenesis. Förster Resonance energy transfer (FRET) analysis of labeled proteins in vitro revealed that in the p97-mediated disassembly step, both SDS22 and I3 dissociate concomitantly, releasing PP1. In presence of a targeting subunit, for instance Growth Arrest and DNA Damage-inducible protein 34 (GADD34), liberated PP1 formed an active holophosphatase that dephosphorylated its substrate, eukaryotic translation initiation factor 2 alpha (eIF2α). Inhibition of p97 results in displacement of the GADD34 targeting subunit by rebinding of PP1 to SDS22 and I3 indicating that the SDS22-PP1-I3 complex is thermodynamically favored. Likewise, p97 inhibition in cells causes rapid sequestration of PP1 by free SDS22 and I3 at the expense of other subunits. This suggests that PP1 exists in a steady state maintained by spontaneous SDS22-PP1-I3 formation and adenosine triphosphate (ATP) hydrolysis, p97-driven disassembly that recycles active PP1 between different holophosphatase complexes to warrant a dynamic holophosphatase landscape.

Loss of Smek1 Induces Tauopathy and Triggers Neurodegeneration by Regulating Microtubule Stability.

Suppressor of Mek1 (Smek1) is a regulatory subunit of protein phosphatase 4. Genome-wide association studies have shown the protective effect of SMEK1 in Alzheimer's disease (AD). However, the physiological and pathological roles of Smek1 in AD and other tauopathies are largely unclear. Here, the role of Smek1 in preventing neurodegeneration is investigated in tauopathy. Smek1 is downregulated in the aged human brain. Through single-cell sequencing, a novel neuronal cluster is identified that possesses neurodegenerative characteristics in Smek1-/- mice. Smek1 deficiency caused markedly more severe motor and cognitive impairments in mice, as well as neuronal loss, gliosis, and tau hyperphosphorylation at major glycogen synthase kinase 3β (Gsk3β) sites. Protein-protein interaction analysis revealed that the Ran-binding domain (RanBD) in the N-terminus of Smek1 facilitated binding with kinesin family member 2A (Kif2a). Depletion of Smek1 resulted in cytoplasmic aggregation of Kif2a, axon outgrowth defects, and impaired mitochondrial axonal trafficking. Downregulation of Kif2a markedly attenuated tau hyperphosphorylation and axon outgrowth defects in shSmek1 cells. For the first time, this study demonstrates that Smek1 deficiency progressively induces neurodegeneration by exacerbating tau pathology and mitochondrial dysfunction in an age-dependent manner.

The ULK1 effector BAG2 regulates autophagy initiation by modulating AMBRA1 localization

Autophagy initiation is regulated by the ULK1 kinase complex. To gain insights into functions of the holo-complex, we generated a deep interactome by combining affinity purification- and proximity labeling-mass spectrometry of all four complex members: ULK1, ATG13, ATG101, and RB1CC1/FIP200. Under starvation conditions, the ULK1 complex interacts with several protein and lipid kinases and phosphatases, implying the formation of a signalosome. Interestingly, several selective autophagy receptors also interact with ULK1, indicating the activation of selective autophagy pathways by nutrient starvation. One effector of the ULK1 complex is the HSC/HSP70 co-chaperone BAG2, which regulates the subcellular localization of the VPS34 lipid kinase complex member AMBRA1. Depending on the nutritional status, BAG2 has opposing roles. In growth conditions, the unphosphorylated form of BAG2 sequesters AMBRA1, attenuating autophagy induction. In starvation conditions, ULK1 phosphorylates BAG2 on Ser31, which supports the recruitment of AMBRA1 to the ER membrane, positively affecting autophagy.

Protein phosphatase 2A regulates blood cell proliferation and differentiation in Drosophila larval lymph glands.

Protein phosphatase 2A (PP2A), one of the most abundant protein phosphatases, has divergent functions in multiple types of cells. Its inactivation has been closely associated with leukemia diseases. However, the physiological function of PP2A for hematopoiesis has been poorly understood in organisms. Drosophila hematopoiesis parallels the vertebrate counterpart in developmental and functional features but involves a much simpler hematopoietic system. Here, utilizing the Drosophila major larval hematopoietic organ lymph gland, we studied the function of PP2A for hematopoiesis in vivo. By knocking down the expression of Pp2A-29B that encodes the scaffold subunit of the PP2A holoenzyme complex, we found that PP2A silencing in the differentiating hemocytes resulted in their excessive proliferation. Furthermore, this PP2A inhibition downregulated the expression of Smoothened (Smo), a crucial component in the Hedgehog pathway, and smo overexpression was able to rescue the phenotypes of PP2A depletion, indicating that Smo functions as a downstream effector of PP2A to restrict the hemocyte proliferation. PDGF/VEGF-receptor (Pvr) overexpression also restored the Smo expression and lymph gland morphology of PP2A silencing, suggesting a PP2A-Pvr-Smo axis to regulate lymph gland growth and hemocyte proliferation. Moreover, inhibiting PP2A activity in the blood progenitor cells promoted their differentiation, but which was independent with Smo. Together, our data suggested that PP2A plays a dual role in the Drosophila lymph gland by preserving the progenitor population and restraining the hemocyte proliferation, to properly regulate the hematopoietic process.

TaNAC1 boosts powdery mildew resistance by phosphorylation-dependent regulation of TaSec1a and TaCAMTA4 via PP2Ac/CDPK20.

The integrity of wheat (Triticum aestivum) production is increasingly jeopardized by the fungal pathogen Blumeria graminis f. sp. tritici (Bgt), particularly amid the vicissitudes of climate change. Here, we delineated the role of a wheat transcription factor, TaNAC1, which precipitates cellular apoptosis and fortifies resistance against Bgt. Utilizing BiFC, co-immunoprecipitation, protein quantification, luciferase report assays, we determined that cytoplasmic TaNAC1-7A undergoes phosphorylation at the S184/S258 sites by TaCDPK20, facilitating its nuclear translocation. This migration appears to prime further phosphorylation by TaMPK1, thereby enhancing transcriptional regulatory activity. Notably, the apoptotic activity of phosphorylated TaNAC1-7A is negatively modulated by the nuclear protein phosphatase PP2Ac. Furthermore, activation of TaNAC1 phosphorylation initiates transcription of downstream genes TaSec1a and TaCAMTA4, through binding to the C[T/G]T[N7]A[A/C]G nucleic acid motif. Suppression of TaNAC1, TaCDPK20, and TaMPK1 in wheat compromises its resistance to Bgt strain E09, whereas overexpression of TaNAC1 and silencing of PP2Ac markedly elevate resistance levels. Our results reveal the pivotal role of TaNAC1 in basal resistance which is mediated by its effects on homotypic fusion, vacuolar protein sorting, and the expression of defense-related genes. The findings highlight the potential through targeting TaNAC1 and its regulators as a strategy for improving wheat's resistance to fungal pathogens.

Bud14 function is crucial for spindle pole body size maintenance.

Spindle pole bodies (SPB), the functional equivalent of centrosomes in yeast, duplicate through generation of a new SPB next to the old one. However, SPBs are dynamic structures that can grow and exchange, and mechanisms that regulate SPB size remain largely unknown. This study aims to elucidate the role of Bud14 in SPB size maintenance in Saccharomyces cerevisiae. We employed quantitative fluorescence microscopy to assess the relative and absolute amounts of SPB structural proteins at SPBs of wildtype cells and in cells lacking BUD14 (bud14Δ). Quantifications were performed using asynchronous cell cultures, as well as cultures synchronously progressing through the cell cycle and upon different cell cycle arrests. We also utilized mutants that allow the separation of Bud14 functions. Our results indicate that higher levels of SPB inner, outer, and central plaque proteins are present at the SPBs of bud14Δ cells compared to wildtype cells during anaphase, as well as during nocodazole-induced M-phase arrest. However, during α-factor mediated G1 arrest, inner and outer plaque proteins responded differently to the absence of BUD14. A Bud14 mutant that cannot interact with the Protein Phosphatase 1 (Glc7) phenocopied bud14Δ in terms of SPB-bound levels of the inner plaque protein Spc110, whereas disruption of Bud14-Kel1-Kel2 complex did not alter Spc110 levels at SPBs. In cells synchronously released from α-factor arrest, lack of Bud14-Glc7 caused increase of Spc110 at the SPBs at early stages of the cell cycle. We identified Bud14 as a critical protein for SPB size maintenance. The interaction of Bud14 with Glc7, but not with the Kelch proteins, is indispensable for restricting levels of Spc110 incorporated into the SPBs.

Development and evaluation of the model for acute kidney injury in patients with cardiac arrest after successful resuscitation

BackgroundThis study aims to construct a clinical prediction model and create a visual line chart depicting the risk of acute kidney injury (AKI) following resuscitation in cardiac arrest (CA) patients. Additionally, the study aims to validate the clinical predictive accuracy of the developed model.MethodsData were retrieved from the Dryad database, and publicly shared data were downloaded. This retrospective cohort study included 347 successfully resuscitated patients post-cardiac arrest from the Dryad database. Demographic and clinical data of patients in the database, along with their renal function during hospitalization, were included. Through data analysis, the study aimed to explore the relevant influencing factors of acute kidney injury (AKI) in patients after cardiopulmonary resuscitation. The study constructed a line chart prediction model using multivariate logistic regression analysis with post-resuscitation shock status (Post-resuscitation shock refers to the condition where, following successful cardiopulmonary resuscitation after cardiac arrest, some patients develop cardiogenic shock.), C reactive protein (CRP), Lactate dehydrogenase (LDH), and Alkaline phosphatase (ALP) identified as predictive factors. The predictive efficiency of the fitted model was evaluated by the area under the curve (AUC) of the receiver operating characteristic (ROC) curve.ResultsMultivariate logistic regression analysis showed that post-resuscitation shock status, CRP, LDH, and PAL were the influencing factors of AKI after resuscitation in CA patients. The calibration curve test indicated that the prediction model was well-calibrated, and the results of the Decision Curve Analysis (DCA) demonstrated the clinical utility of the model constructed in this study.ConclusionPost-resuscitation shock status, CRP, LDH, and ALPare the influencing factors for AKI after resuscitation in CA patients. The clinical prediction model constructed based on the above indicators has good clinical discriminability and practicality.

Photo-Claisen Rearrangement in a Coumarin-Caged Peptide Leads to a Surprising Enzyme Hyperactivation.

Protein phosphatase-1 (PP1) is a ubiquitous enzyme that counteracts hundreds of kinases in cells. PP1 interacts with regulatory proteins via an RVxF peptide motif that binds to a hydrophobic groove on the enzyme. PP1-disrupting peptides (PDPs) compete with these regulatory proteins, leading to the release of the active PP1 subunit and promoting substrate dephosphorylation. Building on previous strategies employing the ortho-nitrobenzyl (o-Nb) group as a photocage to control PDP activity, we introduced coumarin derivatives into a PDP via an ether bond to explore their effects on PP1 activity. Surprisingly, our study revealed that the coumarin-caged peptides (PDP-DEACM and PDP-CM) underwent a photo-Claisen rearrangement, resulting in an unexpected hyperactivation of PP1. Our findings underscore the importance of linker design in controlling uncaging efficiency of photocages and highlight the need for comprehensive in vitro analysis before cellular experiments.

Docking interactions determine substrate specificity of members of a widespread family of protein phosphatases

How protein phosphatases achieve specificity for their substrates is a major outstanding question. PPM family serine/threonine phosphatases are widespread in bacteria and eukaryotes, where they dephosphorylate target proteins with a high degree of specificity. In bacteria, PPM phosphatases control diverse transcriptional responses by dephosphorylating anti-anti-sigma factors of the STAS domain family, exemplified by B. subtilis phosphatases SpoIIE, which controls cell-fate during endospore formation, and RsbU, which initiates the General Stress Response. Using a combination of forward genetics, biochemical reconstitution, and AlphaFold2 structure prediction, we identified a conserved, tripartite substrate docking interface comprised of three variable loops on the surface of the PPM phosphatase domains of SpoIIE and RsbU that recognize the three-dimensional structure of the substrate protein. Non-conserved amino acids in these loops facilitate the accommodation of the cognate substrate and prevent dephosphorylation of the non-cognate substrate. Together, single-amino acid substitutions in these three elements cause an over five-hundred fold change in specificity. Our data additionally suggest that substrate-docking interactions regulate phosphatase specificity through a conserved allosteric switch element that controls the catalytic efficiency of the phosphatase by positioning the metal cofactor and substrate. We hypothesize that this is a generalizable mechanistic model for PPM family phosphatase substrate specificity. Importantly, the substrate docking interface with the phosphatase is only partially overlapping with the much more extensive interface with the upstream kinase, suggesting the possibility that kinase and phosphatase specificity evolved independently.

MiR-449a mediated repression of the cell cycle machinery prevents neuronal apoptosis

Aberrant activation of the cell cycle of terminally-differentiated neurons results in their apoptosis and is known to contribute to neuronal loss in various neurodegenerative disorders like Alzheimer's Disease. However, the mechanisms that regulate Cell Cycle Related Neuronal Apoptosis (CRNA) are poorly understood. We identified several miRNA that are dysregulated in neurons from a transgenic APP/PS1 mouse model for AD (TgAD). Several of these miRNA are known to and/or are predicted to target cell cycle-related genes. Detailed investigation on miR-449a revealed: a. it promotes neuronal differentiation by suppressing the neuronal cell cycle; b. its expression in cortical neurons was impaired in response to amyloid peptide Aβ42; c. loss of its expression resulted in aberrant activation of the cell cycle leading to apoptosis. miR-449a may prevent CRNA by targeting cyclin D1 and protein phosphatase CDC25A, which are important for G1-S transition. Importantly, the lentiviral mediated delivery of miR-449a in TgAD mouse brain significantly reverted the defects in learning and memory, which are associated with AD.

Clinical characteristics, longitudinal adaptive functioning, and association with electroencephalogram activity in PPP2R5D-related neurodevelopmental disorder.

Protein phosphatase 2 regulatory subunit B56δ related neurodevelopmental disorder (PPP2R5D-related NDD) is largely caused by de novo heterozygous missense PPP2R5D variants. We report medical characteristics, longitudinal adaptive functioning, and in-person neurological, motor, cognitive, and electroencephalogram (EEG) activity for PPP2R5D-related NDD. Forty-two individuals (median age 6 years, range = 0.8-25.3) with pathogenic/likely pathogenic PPP2R5D variants were assessed, and almost all variants were missense (97.6%) and de novo (85.7%). Common clinical symptoms were developmental delay, hypotonia, macrocephaly, seizures, autism, behavioral challenges, and sleep problems. The mean Gross motor functional measure-66 was 60.2 ± 17.3% and the mean Revised upper limb module score was 25.9 ± 8.8. The Vineland-3 adaptive behavior composite score (VABS-3 ABC) at baseline was low (M = 61.7 ± 16.8). VABS-3 growth scale value scores increased from baseline in all subdomains (range = 0.6-5.9) after a mean follow-up of 1.3 ± 0.3 years. EEG beta and gamma power were negatively correlated with VABS-3 score; p < 0.05. Individuals had a mean Quality-of-life inventory-disability score of 74.7 ± 11.4. Twenty caregivers (80%) had a risk of burnout based on the Caregiver burden inventory. Overall, the most common clinical manifestations of PPP2R5D-related NDD were impaired cognitive, adaptive function, and motor skills; and EEG activity was associated with adaptive functioning. This clinical characterization describes the natural history in preparation for clinical trials.