Loss of PI3k activity of inositol polyphosphate multikinase impairs PDK1-mediated AKT activation, cell migration, and intestinal homeostasis

IPMK depletion influences genome-wide DNA methylation

Inositol polyphosphate multikinase (IPMK) is emerging as a critical regulator of nuclear functions. While earlier studies in yeast and cell lines linked IPMK to gene expression, recent work reveals its role in modulating histone acetylation through the activation of histone deacetylases 1/3 (HDAC1/3). Interestingly, HDAC1/3 interact with DNA methyltransferase 1 (DNMT1), stabilizing DNMT1 and promoting DNA methylation. As an HDAC1/3 activator, IPMK may thereby influence DNA methylation dynamics. This study investigates how the genetic depletion of IPMK influences DNA methylation, though the role of its kinase activity remains untested. Using long-read Oxford nanopore sequencing, we conducted methylation analysis for >28 millions of CpG sites and discovered that IPMK deletion results in over 22,000 differentially methylated regions (DMRs). Integrating affected genes by DMRs and RNA-seq data, we found that 35 genes show an inverse correlation between methylation in promoter regions and gene expression. Pathway analysis revealed that genes related to tissue remodeling and hematopoiesis are affected. Notably, MMP14 and LIF showed significant methylation changes in promoter regions under IPMK deletion, resulting in decreased mRNA and protein expression. Collectively, this study identifies IPMK as a novel regulator of DNA methylation. While this study did not investigate the role of IPMK's kinase activity in regulating DNA methylation, future studies will determine whether IPMK's effects on DNA methylation are driven by its kinase activity or by kinase-independent mechanisms.

Effects of hydroxypropyl starch on intestinal health and transcriptome of geese

In recent years, gout resulting from uric acid metabolism disorders has led to significant economic losses in goose production. The intestine is a vital organ crucial for uric acid metabolism. Hydroxypropyl starch (HPS) is a resistant starch modified from natural starch, which can enhance intestinal health as a dietary ingredient fiber. In this study, 240 30-day-old Yangzhou geese with similar body weights were divided into three groups: The control group (CG) received a basal diet + 5% corn starch; the hydroxypropyl starch group (HPS) and the sodium urate group (SU) were given a basal diet + 5% hydroxypropyl starch. The experiment lasted for 21 days, and the SU group was administered 30 mg of sodium urate per day during the last 4 days of the study. The results indicated that the level of uric acid in the HPS group was 56.6 µmol/L, significantly lower than that in the CG group (70.8 µmol/L) and the SU group (129.7 µmol/L). The morphological findings revealed that the ileum of the CG group and the SU group exhibited varying degrees of damage, while the HPS group maintained complete structure. The villus height and the ratio of villus height to crypt depth in the HPS group were significantly higher compared to those in the CG and SU groups, while the crypt depth was significantly lower than that in the SU group. A total of 1462 differentially expressed genes (DEGs) were identified at the transcriptome level. GO and KEGG functional enrichment analyses indicated that the DEGs were significantly enriched in the Brush border membrane, Brush border, PPAR signaling pathway, PI3K-Akt signaling pathway, and other related processes. Subsequent analysis revealed that HPS up-regulated the expression of genes associated with intestinal function (such as SLC5A12 and SLC5A8), structure (including NR5A2, IPMK), and uric acid metabolism (PDZK1). The accuracy and reliability of transcriptome sequencing data were confirmed by RT-qPCR. In this study, we systematically demonstrated that HPS can improve intestinal morphology and reduce serum uric acid levels, emphasizing its potential as a dietary supplement for geese.

Inositol polyphosphate multikinase regulates Th1 and Th17 cell differentiation by controlling Akt-mTOR signaling

Activated proinflammatory T helper (Th) cells, including Th1 and Th17 cells, drive immune responses against pathogens and contribute to autoimmune diseases. We show that the expression of inositol polyphosphate multikinase (IPMK), an enzyme essential for inositol phosphate metabolism, is highly induced in Th1 and Th17 subsets. Deletion of IPMK in CD4+ T cells leads to diminished Th1- and Th17-mediated responses, reducing resistance to Leishmania major and attenuating experimental autoimmune encephalomyelitis. IPMK-deficient CD4+ T cells show impaired activation and Th17 differentiation, linked to the decreased activation of Akt, mTOR, and STAT3. Mechanistically, IPMK functions as a phosphatidylinositol 3-kinase to regulate phosphatidylinositol (3,4,5)-trisphosphate (PtdIns(3,4,5)P3) production, promoting T cell activation and effector functions. In IPMK-deficient CD4+ T cells, T cell receptor-stimulated PtdIns(3,4,5)P3 generation is abolished by wortmannin, suggesting IPMK acts in a wortmannin-sensitive manner. These findings establish IPMK as a critical regulator of Th1 and Th17 differentiation, underscoring its role in maintaining immune homeostasis.

The inositol phosphate signalling network in physiology and disease

Combinatorial substitution of phosphate groups on the inositol ring gives rise to a plethora of inositol phosphates (InsPs) and inositol pyrophosphates (PP-InsPs). These small molecules constitute an elaborate metabolic and signalling network that influences nearly every cellular function. This review delves into the knowledge accumulated over the past decades regarding the biochemical principles and significance of InsP metabolism. We focus on the biological actions of InsPs in mammals, with an emphasis on recent findings regarding specific target proteins. We further discuss the roles of InsP metabolism in contributing to physiological homeostasis and pathological conditions. A deeper understanding of InsPs and their metabolic pathways holds the potential to address unresolved questions and propel advances towards therapeutic applications.

Inositol Hexaphosphate (InsP6) Activates the HDAC1/3 Epigenetic Axis to Maintain Intestinal Barrier Function

HDACs (histone deacetylase) play a crucial role in regulating gene expression, and the inhibition of these enzymes is gaining attention as a promising therapeutic approach for cancer treatment. Despite their significant physiological and clinical importance, the mechanisms of HDAC activation remain poorly understood. This study reveals that inositol polyphosphate multikinase (IPMK) is essential for activating HDAC1 and HDAC3 in cell lines and mice. IPMK deletion or inactivation of its kinase activity selectively impairs HDAC1/3's deacetylase activity, significantly influencing gene expression. Disruption of the IPMK-HDAC1/3 epigenetic axis results in transcriptional upregulation of matrix metalloproteinase (MMP) genes, exacerbating cell and intestinal permeability. Remarkably, treatment of IPMK KO cells with cell-permeable inositol hexaphosphate (InsP6) rescues these defects. This study elucidates the role of IPMK's kinase activity in HDAC1/3 activation and its implications for intestinal barrier function.

I told you to stop: obscurin's role in epithelial cell migration

The giant cytoskeletal protein obscurin contains multiple cell signaling domains that influence cell migration. Here, we follow each of these pathways, examine how these pathways modulate epithelial cell migration, and discuss the cross-talk between these pathways. Specifically, obscurin uses its PH domain to inhibit phosphoinositide-3-kinase (PI3K)-dependent migration and its RhoGEF domain to activate RhoA and slow cell migration. While obscurin's effect on the PI3K pathway agrees with the literature, obscurin's effect on the RhoA pathway runs counter to most other RhoA effectors, whose activation tends to lead to enhanced motility. Obscurin also phosphorylates cadherins, and this may also influence cell motility. When taken together, obscurin's ability to modulate three independent cell migration pathways is likely why obscurin knockout cells experience enhanced epithelial to mesenchymal transition, and why obscurin is a frequently mutated gene in several types of cancer.

βA3/A1-crystallin is an epigenetic regulator of histone deacetylase 3 (HDAC3) in the retinal pigmented epithelial (RPE) cells

The retinal pigmented epithelial (RPE) cells maintain retinal homeostasis, and alterations in their function contribute to non-exudative age-related macular degeneration (AMD) 1,2 . Here, we explore the intricate relationship between RPE cells, epigenetic modifications, and the development of AMD. Importantly, the study reveals a substantial decrease in histone deacetylase 3 (HDAC3) activity and elevated histone acetylation in the RPE of human AMD donor eyes. To investigate epigenetic mechanisms in AMD development, we used a mouse model with RPE-specific Cryba1 knockout 3-5 , revealing that the loss of βA3/A1-crystallin selectively reduces HDAC3 activity, resulting in increased histone acetylation. βA3/A1-crystallin activates HDAC3 by facilitating its interaction with the casein kinase II (CK2) and phosphorylating HDAC3, as well as by regulating intracellular InsP6 (phytic acid) levels, required for activating HDAC3. These findings highlight a novel function of βA3/A1-crystallin as an epigenetic regulator of HDAC3 in the RPE cells and provide insights into potential therapeutic strategies in non-exudative AMD.

Design, synthesis and cellular characterization of a new class of IPMK kinase inhibitors

Many genetic studies have established the kinase activity of inositol phosphate multikinase (IPMK) is required for the synthesis of higher-order inositol phosphate signaling molecules, the regulation of gene expression and control of the cell cycle. These genetic studies await orthogonal validation by specific IPMK inhibitors, but no such inhibitors have been synthesized. Here, we report complete chemical synthesis, cellular characterization, structure-activity relationships and rodent pharmacokinetics of a novel series of highly potent IPMK inhibitors. The first-generation compound 1 (UNC7437) decreased cellular proliferation and tritiated inositol phosphate levels in metabolically labeled human U251-MG glioblastoma cells. Compound 1 also regulated the transcriptome of these cells, selectively regulating genes that are enriched in cancer, inflammatory and viral infection pathways. Further optimization of compound 1 eventually led to compound 15 (UNC9750), which showed improved potency and pharmacokinetics in rodents. Compound 15 specifically inhibited cellular accumulation of InsP 5 , a direct product of IPMK kinase activity, while having no effect on InsP 6 levels, revealing a novel metabolic signature detected for the first time by rapid chemical attenuation of cellular IPMK activity. These studies designed, optimized and synthesized a new series of IPMK inhibitors, which reduces glioblastoma cell growth, induces a novel InsP 5 metabolic signature, and reveals novel aspects inositol phosphate cellular metabolism and signaling.

X-ray crystallographic analyses of 14 IPMK inhibitor complexes

Inositol polyphosphate multikinase (IPMK) is a ubiquitously expressed kinase that has been linked to several cancers. Here, we report 14 new co-crystal structures (1.7Å - 2.0Å resolution) of human IPMK complexed with various IPMK inhibitors developed by another group. The new structures reveal two ordered water molecules that participate in hydrogen-bonding networks, and an unoccupied pocket in the ATP-binding site of human IPMK. New Protein Data Bank (PDB) codes of these IPMK crystal structures are: 8V6W (1.95Å), 8V6X (1.75Å), 8V6Y (1.70Å), 8V6Z (1.85Å), 8V70 (1.85Å), 8V71 (1.70Å), 8V72 (2.0Å), 8V73 (1.90Å), 8V74 (1.85Å), 8V75 (1.85Å), 8V76 (1.95Å), 8V77 (1.95Å), 8V78 (1.95Å), 8V79 (1.95Å).

Influence of β-catenin signaling on neurogenesis in neuropsychiatric disorders: Anxiety and depression

It has been proven that stress, mainly in the early years of life, can lead to anxiety and mood problems. Current treatments for psychiatric disorders are not enough, and some of them show intolerable side effects, emphasizing the urgent need for new treatment targets. Hence, a better understanding of the different brain networks, which are involved in the response to anxiety and depression, may evoke treatments with more specific targets. One of these targets is β-catenin that regulates brain circuits. β-Catenin has a dual response toward stress, which may influence coping or vulnerability to stress response. Indeed, β-catenin signaling involves several processes such as inflammation-directed brain repair, inflammation-induced brain damage, and neurogenesis. Interestingly, β-catenin reduction is accompanied by low neurogenesis, which leads to anxiety and depression. However, in another state, this reduction activates a compensatory mechanism that enhances neurogenesis to protect against depression but may precipitate anxiety. Thus, understanding the molecular mechanism of β-catenin could enhance our knowledge about anxiety and depression's pathophysiology, potentially improving clinical results by targeting it. Herein, the different states of β-catenin were discussed, shedding light on possible drugs that showed action on psychiatric disorders through β-catenin.

Systematic assessment of the ecotoxicological effects and mechanisms of biochar-derived dissolved organic matter (DOM) on the earthworm Eisenia fetida

Biochar-derived dissolved organic matter (DOM) contains toxic substances that are first released into the soil after biochar application. However, the ecological risks of biochar-derived DOM on soil invertebrate earthworms are unclear. Therefore, this study investigated the ecological risks and toxic mechanisms of sewage sludge biochar (SSB)-derived DOM on the earthworm Eisenia fetida (E. fetida) via microcosm experiments. DOM exposure induced earthworm death, growth inhibition, and cocoon decline. Moreover, DOM, especially the 10% DOM300 (derived from SSB prepared at 300 °C) treatments, disrupted the antioxidant defense response and lysosomal stability in earthworms. Integrated biomarker response v2 (IBRv2) analysis was performed to assess the comprehensive toxicity of DOM in E. fetida, and the results revealed that DOM300 might exert more hazardous effects on earthworms than DOM500 (prepared at 500 °C) and DOM700 (prepared at 700 °C), as revealed by increases in the IBRv2 value of 3.48-18.21. Transcriptome analysis revealed that 10% DOM300 exposure significantly disrupted carbohydrate and protein digestion and absorption and induced endocrine disorder. Interestingly, 10% DOM300 exposure also significantly downregulated the expression of genes involved in signaling pathways, e.g., the P13K-AKT, cGMP-PKG, and ErbB signaling pathways, which are related to cell growth, survival, and metabolism, suggesting that DOM300 might induce neurotoxicity in E. fetida. Altogether, these results may contribute to a better understanding of the toxicity and defense mechanisms of biochar-derived DOM on earthworms, especially during long-term applications, and thus provide guidelines for using biochar as a soil amendment.

Inositol polyphosphate multikinase modulates free fatty acids-induced insulin resistance in primary mouse hepatocytes

Insulin resistance is a critical mediator of the development of nonalcoholic fatty liver disease (NAFLD). An excess influx of fatty acids to the liver is thought to be a pathogenic cause of insulin resistance and the development of NAFLD. Although elevated levels of free fatty acids (FFA) in plasma contribute to inducing insulin resistance and NAFLD, the molecular mechanism is not completely understood. This study aimed to determine whether inositol polyphosphate multikinase (IPMK), a regulator of insulin signaling, plays any role in FFA-induced insulin resistance in primary hepatocytes. Here, we show that excess FFA decreased IPMK expression, and blockade of IPMK decrease attenuated the FFA-induced suppression of protein kinase B (Akt) phosphorylation in primary mouse hepatocytes (PMH). Moreover, overexpression of IPMK prevented the FFA-induced suppression of Akt phosphorylation by insulin, while knockout of IPMK exacerbated insulin resistance in PMH. In addition, treatment with MG132, a proteasomal inhibitor, inhibits FFA-induced decrease in IPMK expression and Akt phosphorylation in PMH. Furthermore, treatment with the antioxidant N-acetyl cysteine (NAC) significantly attenuated the FFA-induced reduction of IPMK and restored FFA-induced insulin resistance in PMH. In conclusion, our findings suggest that excess FFA reduces IPMK expression and contributes to the FFA-induced decrease in Akt phosphorylation in PMH, leading to insulin resistance. Our study highlights IPMK as a potential therapeutic target for preventing insulin resistance and NAFLD.

Alcohol Dependence Modulates Amygdalar mTORC2 and PKCε Expression in a Rodent Model

Multiple alcohol use disorder (AUD)-related behavioral alterations are governed by protein kinase C epsilon (PKCε), particularly in the amygdala. Protein kinase C (PKC) is readily phosphorylated at Ser729 before activation by the mTORC2 protein complex. In keeping with this, the current study was conducted to assess the variations in mTORC2 and PKCε during different ethanol exposure stages. The following groups of rats were employed: control, acute, chronic, ethanol withdrawal (EW), and EW + ethanol (EtOH). Ethanol-containing and non-ethanol-containing modified liquid diets (MLDs) were administered for 27 days. On day 28, either saline or ethanol (2.5 g/kg, 20% v/v) was intraperitoneally administered, followed by bilateral amygdala extraction. PKCε mRNA levels were noticeably increased in the amygdala of the EW + EtOH and EW groups. Following chronic ethanol consumption, the stress-activated map kinase-interacting protein 1 (Sin1) gene expression was markedly decreased. In the EW, EW + EtOH, and chronic ethanol groups, there was a profound increase in the protein expression of mTOR, Sin1, PKCε, and phosphorylated PKCε (Ser729). The PKCε gene and protein expressions showed a statistically significant moderate association, according to a correlation analysis. Our results suggest that an elevated PKCε protein expression in the amygdala during EW and EW + EtOH occurred at the transcriptional level. However, an elevation in the PKCε protein expression, but not its mRNA, after chronic ethanol intake warrants further investigation to fully understand the signaling pathways during different episodes of AUD.