Clathrin-mediated endocytosis (CME) internalizes cell-surface receptors via clathrin-coated invaginations of the plasma membrane. Both clathrin and endocytic cargo are recruited to these sites by the adaptor protein complex AP2. AP2 cycles between a closed cytoplasmic conformation and an open membrane-bound state, and efficient CME requires both conformations and their dynamic interconversion. The mechanisms regulating these conformational changes, which include post-translational modifications of the AP2, remain incompletely understood. Here, we report that, in human cell lines, p70S6 kinase phosphorylates the μ2 subunit of the AP2 and that the phosphorylation of serine 45 (S45) depends on p70S6K activity. Loss of S45-μ2 phosphorylation results in decreased internalization of canonical CME cargo, such as transferrin and PDGF receptors. In Caenorhabditis elegans, lack of S45-μ2 phosphorylation produces directionally similar but markedly weaker phenotypes than AP2 loss of function. Live imaging and computational dynamic modelling suggest that S45-μ2 phosphorylation has an impact on the conformational changes of the AP2 complex. These findings identify a p70S6K-dependent mechanism that modulates AP2 function and further strengthen the importance of post-translational regulation in controlling CME.

Midkine (MDK), a multifunctional growth factor, has been implicated in promoting tumor progression, yet its role in glioblastoma (GBM) remains insufficiently characterized. To investigate MDK’s function in glioma, we integrated four RNA-Seq datasets into a harmonized cohort of 1,017 adult gliomas, including 256 GBM samples. We complemented this with freshly collected human GBM tissues and matched primary cell cultures to evaluate MDK expression and secretion patterns, further contextualized using single-cell RNA-Seq. Finally, we tested the impact of GBM-derived MDK on macrophage secretome composition to validate our in silico observations. We found that MDK expression increases with tumor grade in IDHwildtype gliomas, accompanied by a shift in isoform proportions favoring the canonical MDK transcript. High MDK expression was associated with poor prognosis specifically in GBM, where the MDKhigh subgroup comprised 75% of cases. MDKhigh GBMs exhibited a distinctive multiomic signature, including elevated chemokine and cytokine expression. Functionally, GBM-derived MDK induced macrophages to secrete multiple cytokines and chemokines, suggesting its role in reshaping the tumor microenvironment. Our findings reveal MDK’s previously underappreciated role in GBM aggressiveness and immune modulation, underscoring its potential as a biomarker and actionable therapeutic target for most GBM patients.

Endometriosis is a common chronic gynaecological disorder related to the presence of ectopic foci of endometrial-like tissue, mostly in the pelvic cavity. Pathogenesis of this disease may be associated with epithelial-to-mesenchymal transition (EMT), a phenomenon defined by morphological and functional changes from epithelial to mesenchymal cell phenotype. The role of EMT in the development of endometriotic lesions remains poorly understood. There is also little known about the role of EMT in the eutopic endometrium in course of the menstrual cycle. Therefore, the present study was aimed at investigating the expression of major EMT-related genes of TGF-β, ZEB, SNAIL, CDH, and miR200 families in eutopic endometrium of women with and without endometriosis in the proliferative and secretory phase of the menstrual cycle. The study included 46 women with endometriosis and 30 control women without symptoms of the disease. Eutopic endometrial tissue samples were collected during the mid-proliferative and mid-secretory phases. Tissue localization of the tested factors was detected by immunohistochemical staining. Expression of specific RNAs was evaluated by quantitative RT-PCR. Differences between groups were determined using the Student’s t-test, Wilcoxon matched-pairs signed rank test or Mann–Whitney U-test. All investigated factors were expressed in the eutopic endometrium, both at the protein and mRNA levels. Comparison of mRNA expression during different cycle phases has revealed a significant upregulation of SNAI2 mRNA in the secretory phase in both the endometriosis and control groups. The secretory phase was also associated with a decreased expression of CDH2 mRNA in the control group. However, a similar difference was not revealed in the endometriosis patients. There were no differences in mRNA levels of the other tested EMT-related factors between the endometriosis and control groups, regardless of the cycle phase. The present study shows that SNAI2 expression is upregulated during the secretory phase of the menstrual cycle, thus suggesting its role in the physiology of the cyclic endometrial changes. However, our data argue for a limited role of EMT in eutopic endometrium in the pathogenesis of endometriosis. These findings put new light on the physiology of the endometrium and the role of EMT in the pathogenesis of endometriosis.

Clathrin-mediated endocytosis (CME) is a process in which ligands and their corresponding receptors at the cell surface are internalized via clathrin-coated invaginations of the plasma membrane. Both clathrin and endocytic cargo are recruited to the clathrin-coated pit by the adaptor protein complex AP2. AP2 resides in the cytoplasm in the closed conformation and opens upon interacting with the plasma membrane. Effective CME requires both pools of AP2, open and closed, and effective transition between these states but the mechanisms regulating this transition are only partially understood. Here, we report that serine 45 (S45) of the µ2 subunit of the AP2 complex is phosphorylated in a p70S6 kinase-dependent manner in HeLa cells both with hyperactivated mTOR signaling and under basal conditions. We demonstrate that the loss of S45-µ2 phosphorylation results in decreased internalization of canonical CME cargo such as transferrin and PDGF receptors. In Caenorhabditis elegans, the absence of S45-µ2 phosphorylation produces the dumpy phenotype characteristic of the loss of function of AP2. Our live imaging experiments further suggest that these phenotypes might arise because S45-μ2 phosphorylation is needed for conformational changes of the AP2 complex. These findings uncover a mechanism central to CME control and extend our knowledge on the role of post-translational modifications of AP2 components in regulating the function of this complex. ### Competing Interest Statement The authors have declared no competing interest.

Endometriosis is a common chronic disorder characterized by the growth of endometrium-like tissue outside the uterine cavity. The disease is associated with chronic inflammation and pelvic pain and may have an impact on the patient’s fertility. The causative factors and pathophysiology of the disease are still poorly recognized. The dysregulation of the immune system, aberrant tissue remodeling, and angiogenesis contribute to the disease progression. In endometriosis patients, the proteins regulating the breakdown and reorganization of the connective tissue, e.g., collagenases, and other proteases, as well as their inhibitors, show an incorrect pattern of expression. Here, we report that the expression of reversion-inducing cysteine-rich protein with Kazal motifs (RECK), one of the inhibitors of connective tissue proteases, is elevated in endometrioma cysts as compared to normal endometrium from unaffected women. We also demonstrate a reduced level of miR200b in endometriotic tissue that correlates with RECK mRNA levels. Furthermore, we employ the 12Z cell line, derived from a peritoneal endometriotic lesion, and the Ishikawa cell line, originating from endometrial adenocarcinoma to identify RECK as a direct target of miR200b. The described effect of miR200b on RECK, together with the aberrant expression of both genes in endometrioma, may help to understand the role played by the tissue remodeling system in the pathogenesis of endometriosis.

Proteasome inhibitors are moieties targeting the proteolytic activity of a proteasome, with demonstrated efficacy in certain hematological malignancies and candidate drugs in other types of cancer, including glioblastoma (GBM). They disturb the levels of proteasome-regulated proteins and lead to the cell cycle inhibition and apoptosis of GBM cells. The accumulation of cell cycle inhibitors p21 and p27, and decreased levels of prosurvival molecules NFKB, survivin, and MGMT, underlie proteasome inhibitors' cytotoxicity when used alone or in combination with the anti-GBM cytostatic drug temozolomide (TMZ). The evidence gathered in preclinical studies substantiated the design of clinical trials that employed the two most promising proteasome inhibitors, bortezomib and marizomib. The drug safety profile, maximum tolerated dose, and interaction with other drugs were initially evaluated, mainly in recurrent GBM patients. A phase III study on newly diagnosed GBM patients who received marizomib as an adjuvant to the Stupp protocol was designed and completed in 2021, with the Stupp protocol receiving patients as a parallel control arm. The data from this phase III study indicate that marizomib does not improve the PFS and OS of GBM patients; however, further analysis of the genetic and epigenetic background of each patient tumor may shed some light on the sensitivity of individual patients to proteasome inhibition. The mutational and epigenetic makeup of GBM cells, like genetic alterations to TP53 and PTEN, or MGMT promoter methylation levels may actually determine the response to proteasome inhibition.

Abstract Chemokines play an integral role in cancer immunoevasion by modulating leukocyte infiltration. They selectively increase the migration of immunosuppressive cells while impairing the infiltration of cytotoxic lymphocytes with potent antitumor activity. Some cancer-associated chemokines may also enhance tumor progression by acting as growth factors or promoting epithelial-mesenchymal transition. Here, we acquired fresh human glioblastoma (GBM) tissues to define chemokine expression patterns in GBM tumors by integrating bulk and single-cell RNA sequencing of both tumor and healthy brain tissues along with Luminex secretome profiling of GBM primary cell cultures. Extensive mapping of GBM-associated chemokines has enabled us to gain insight into intratumoral chemokine-mediated cell-to-cell communication. Among others, we identified CCL7 and midkine (MDK) to play a crucial role in the formation of the hostile tumor microenvironment (TME) in GBM. We hypothesize that these chemoattractants can facilitate the GBM tumor growth by recruiting M2 macrophages, promoting epithelial-mesenchymal transition, and activating the prosurvival PI3K-Akt pathway. Indeed, high expression of both chemokines was linked to poor overall survival. Additionally, by integrating the data, we further identified the cellular source of the most abundantly secreted chemokines in GBM tumors. Since immune cells require TME infiltration to mediate an appropriate antitumor response, impaired tumor infiltration is one of the critical limiting factors for cancer cell therapy. Our chemokine atlas provides novel targets to enhance adoptive cell therapies by improving the potential of effector cells for tumor homing and anticancer activities in GBM. This research was funded by the National Science Centre, Poland (2020/37/B/NZ6/02191), the Polish Ministry of Science and Higher Education (grant number DI2018 020548), and the National Centre for Research and Development (STRATEGMED3/307326/6/NCBR/2017).

Despite numerous efforts aiming to characterise glioblastoma pathology (GBM) and discover new therapeutic strategies, GBM remains one of the most challenging tumours to treat. Here we propose the optimisation of in vitro culturing of GBM patient-derived cells, namely the establishment of GBM-derived cultures and their maintenance at oxygen tension mimicking oxygenation conditions occurring within the tumour. To globally analyse cell states, we performed the transcriptome analysis of GBM patient-derived cells kept as spheroids in serum-free conditions at the reduced oxygen tension (5% O2), cells cultured at atmospheric oxygen (20% O2), and parental tumour. Immune cells present in the tumour were depleted, resulting in the decreased expression of the immune system and inflammation-related genes. The expression of genes promoting cell proliferation and DNA repair was higher in GBM cell cultures when compared to the relevant tumour sample. However, lowering oxygen tension to 5% did not affect the proliferation rate and expression of cell cycle and DNA repair genes in GBM cell cultures. Culturing GBM cells at 5% oxygen was sufficient to increase the expression of specific stemness markers, particularly the PROM1 gene, without affecting neural cell differentiation markers. GBM spheroids cultured at 5% oxygen expressed higher levels of hypoxia-inducible genes, including those encoding glycolytic enzymes and pro-angiogenic factors. The genes up-regulated in cells cultured at 5% oxygen had higher expression in parental GBMs compared to that observed in 20% cell cultures, suggesting the preservation of the hypoxic component of GBM transcriptome at 5% oxygen and its loss in standard culture conditions. Evaluation of expression of those genes in The Cancer Genome Atlas dataset comprising samples of normal brain tissue, lower-grade gliomas and GBMs indicated the expression pattern of the indicated genes was specific for GBM. Moreover, GBM cells cultured at 5% oxygen were more resistant to temozolomide, the chemotherapeutic used in GBM therapy. The presented comparison of GBM cultures maintained at high and low oxygen tension together with analysis of tumour transcriptome indicates that lowering oxygen tension during cell culture may more allegedly reproduce tumour cell behaviour within GBM than standard culture conditions (e.g., atmospheric oxygen tension). Low oxygen culture conditions should be considered as a more appropriate model for further studies on glioblastoma pathology and therapy.

The development of an effective method of melanocyte isolation and culture is necessary for basic and clinical studies concerning skin diseases, including skin pigmentation disorders and melanoma. In this paper, we describe a novel, non-enzymatic and effective method of skin melanocyte and metastatic melanoma cell isolation and culture (along with the spontaneous spheroid creation) from skin or lymph node explants. The method is based on the selective harvesting of melanocytes and melanoma cells emigrating from the cultured explants. Thereby, isolated cells retain their natural phenotypical features, such as expression of tyrosinase and Melan-A as well as melanin production and are not contaminated by keratinocytes and fibroblasts. Such melanocyte and melanoma cell cultures may be very useful for medical and cosmetology studies, including studies of antitumor therapies.

Curcumin (diferuloylmethane) derived from the rhizome of Curcuma longa L. has been used for thousands of years in traditional Chinese medicine and Ayurvedic medicine in Asian countries to treat liver diseases, rheumatoid diseases, diabetes, atherosclerosis, infectious diseases and cancer. It exhibits a wide range of pharmacological properties, which include antioxidant, anti-inflammatory, antimutagenic, antimicrobial and anticancer activity. Herein the mechanisms of curcumin impact on oxidative stress, angiogenesis and inflammatory processes are described indicating that curcumin use may inhibit those pathological conditions and restore body homeostasis. Its effectiveness was also proved for major eye diseases. In this review, the influence of curcumin on eye diseases, such as glaucoma, cataract, age-related macular degeneration, diabetic retinopathy, corneal neovascularization, corneal wound healing, dry eye disease, conjunctivitis, pterygium, anterior uveitis are reported. The analysis of a number of clinical and preclinical investigations indicates that curcumin may be used as a therapeutic agent in the treatment of various eye disorders.

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Background: Glycogen synthase kinase-3 beta (GSK3 beta) is a key regulator of cellular homeostasis. In neurons, GSK3 beta contributes to the control of neuronal transmission and plasticity, but its role in epilepsy remains to be defined. Methods: Biochemical and electrophysiological methods were used to assess the role of GSK3 beta in regulating neuronal transmission and epileptogenesis. GSK3 beta activity was increased genetically in GSK3 beta[S9A] mice. Its effects on neuronal transmission and epileptogenesis induced by kainic acid were assessed by field potential recordings in mice brain slices and video electroencephalography in vivo. The ion channel expression was measured in brain samples from mice and followed by analysis in samples from patients with temporal lobe epilepsy or focal cortical dysplasia in correlation to GSK3 beta phosphorylation. Findings: Higher GSK3 beta activity decreased the progression of kainic acid induced epileptogenesis. At the biochemical level, higher GSK3 beta activity increased the expression of hyperpolarization-activated cyclic nucleotide-gated (HCN) channel 4 under basal conditions and in the epileptic mouse brain and decreased phosphorylation of the glutamate alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subunit GluA1 at Serine 831 under basal conditions. Moreover, we found a significant correlation between higher inhibitory-GSK3 beta phosphorylation at Serine 9 and higher activating GluA1 phosphorylation at Serine 845 in brain samples from epileptic patients. Interpretation: Our data imply GSK3 beta activity in the protection of neuronal networks from hyper-activation in response to epileptogenic stimuli and indicate that the anti-epileptogenic function of GSK3 beta involves modulation of HCN4 level and the synaptic AMPA receptors pool. (c) 2018 The Authors. Published by Elsevier B.V.

The selective and neuronal activity-dependent degradation of synaptic proteins appears to be crucial for long-term synaptic plasticity. One such protein is activity-regulated cytoskeleton-associated protein (Arc), which regulates the synaptic content of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPAR), excitatory synapse strength and dendritic spine morphology. The levels of Arc protein are tightly regulated, and its removal occurs via proteasome-mediated degradation that requires prior ubiquitination. Glycogen synthase kinases α and β (GSK3α, GSKβ; collectively named GSK3α/β) are serine-threonine kinases with abundant expression in the central nervous system. Both GSK3 isozymes are tonically active under basal conditions, but their activity is regulated by intra- and extracellular factors, intimately involved in neuronal activity. Similar to Arc, GSK3α and GSK3β contribute to synaptic plasticity and the structural plasticity of dendritic spines. The present study identified Arc as a GSK3α/β substrate and showed that GSKβ promotes Arc degradation under conditions that induce de novo Arc synthesis. We also found that GSK3α/β inhibition potentiated spine head thinning that was caused by the prolonged stimulation of N-methyl-D-aspartate receptors (NMDAR). Furthermore, overexpression of Arc mutants that were resistant to GSK3β-mediated phosphorylation or ubiquitination resulted in a stronger reduction of dendritic spine width than wildtype Arc overexpression. Thus, GSK3β terminates Arc expression and limits its effect on dendritic spine morphology. Taken together, the results identify GSK3α/β-catalyzed Arc phosphorylation and degradation as a novel mechanism for controlling the duration of Arc expression and function.

Glycogen synthase kinases-3β (GSK3β) is a key regulator of cell homeostasis. In neurons, GSK3β contributes to control of neuronal transmission and plasticity. Despite extensive studies in non-neuronal cells, crosstalk between GSK3β and other signaling pathways remains not well defined in neurons. In the present study, we report that GSK3β positively affected the activity of effectors of mammalian target of rapamycin complex 1 (mTORC1) and complex 2 (mTORC2), in mature neurons in vitro and in vivo. GSK3β also promoted prosurvival signaling and attenuated kainic acid-induced apoptosis. Our study identified GSK3β as a positive regulator of prosurvival signaling, including the mTOR pathway, and indicates the possible neuroprotective role of GSK3β in models of pharmacologically induced excitotoxicity.

Although memories appear to be elusive phenomena, they are stored in the network of physical connections between neurons. Dendritic spines, which are actin-rich dendritic protrusions, serve as the contact points between networked neurons. The spines' shape contributes to the strength of signal transmission. To acquire and store information, dendritic spines must remain plastic, i.e., able to respond to signals, by changing their shape. We asked whether glycogen synthase kinase (GSK) 3α and GSK3β, which are implicated in diseases with neuropsychiatric symptoms, such as Alzheimer's disease, bipolar disease and schizophrenia, play a role in a spine structural plasticity. We used Latrunculin B, an actin polymerization inhibitor, and chemically induced Long-Term Depression to trigger fast spine shape remodeling in cultured hippocampal neurons. Spine shrinkage induced by either stimulus required GSK3α activity. GSK3β activity was only important for spine structural changes after treatment with Latrunculin B. Our results indicate that GSK3α is an essential component for short-term spine structural plasticity. This specific function should be considered in future studies of neurodegenerative diseases and neuropsychiatric conditions that originate from suboptimal levels of GSK3α/β activity.

The shape of the dendritic arbor is one of the criteria of neuron classification and reflects functional specialization of particular classes of neurons. The development of a proper dendritic branching pattern strongly relies on interactions between the extracellular environment and intracellular processes responsible for dendrite growth and stability. We previously showed that mammalian target of rapamycin (mTOR) kinase is crucial for this process. In this work, we performed a screen for modifiers of dendritic growth in hippocampal neurons, the expression of which is potentially regulated by mTOR. As a result, we identified Cyr61, an angiogenic factor with unknown neuronal function, as a novel regulator of dendritic growth, which controls dendritic growth in a beta 1-integrin-dependent manner.

Dendrites are the main site of information input into neurons. Their development is a multistep process controlled by mammalian target of rapamycin (mTOR) among other proteins. mTOR is a serine/threonine protein kinase that forms two functionally distinct complexes in mammalian cells: mTORC1 and mTORC2. However, the one that contributes to mammalian neuron development remains unknown. This work used short hairpin RNA against Raptor and Rictor, unique components of mTORC1 and mTORC2, respectively, to dissect mTORC involvement in this process. We provide evidence that both mTOR complexes are crucial for the proper dendritic arbor morphology of hippocampal neurons. These two complexes are required for dendritic development both under basal conditions and upon the induction of mTOR-dependent dendritic growth. We also identified Akt as a downstream effector of mTORC2 needed for proper dendritic arbor morphology, the action of which required mTORC1 and p70S6K1.

Neuroprotective and/or neuroregenerative activity of FK506, its derivatives, and to a lesser extent cyclosporin A (CsA) in animal models of neurodegenerative diseases of different etiology have been reported. Here, we verified a hypothesis that the most likely mechanism of their neuroprotective action is inhibition of the early steps of inflammatory activation of microglia by interference with mitogen-activated protein kinase (MAPK) signaling. The effect of immunosuppressants on lipopolysaccharide (LPS)-induced changes in morphology, proliferation, and motility of rat primary microglial cultures was evaluated. FK506 and CsA directly inhibited LPS-induced microglia activation and inflammatory responses. While both drugs efficiently reduced the expression of iNOS and the release of nitric oxide, only FK506 strongly inhibited the expression of Cox-2 and secretion of the mature form of IL-1β. FK506 strongly reduced LPS-induced activation of MAPK, and its downstream signaling crucial for inflammatory responses. Comparative analysis of global gene expression in rat ischemic brains and in LPS-stimulated microglial cultures revealed many genes and signaling pathways regulated in the same way in both systems. FK506 treatment blocked a majority of genes induced by an ischemic insult in the cortex, in particular inflammatory/innate immunity and apoptosis-related genes. Microglia-mediated inflammation is considered as one of the most important components of brain injury after trauma or stroke; thus, effective and multifaceted blockade of microglial activation by FK506 has clinical relevance and potential therapeutic implications.