Cytoskeletal Rearrangements Research Articles

The Nephrotoxin Puromycin Aminonucleoside Induces Injury in Kidney Organoids Differentiated from Induced Pluripotent Stem Cells.

Kidney diseases, including acute kidney injury (AKI) and chronic kidney disease (CKD), which can progress to end stage renal disease (ESRD), are a worldwide health burden. Organ transplantation or kidney dialysis are the only effective available therapeutic tools. Therefore, in vitro models of kidney diseases and the development of prospective therapeutic options are urgently needed. Within the kidney, the glomeruli are involved in blood filtration and waste excretion and are easily affected by changing cellular conditions. Puromycin aminonucleoside (PAN) is a nephrotoxin, which can be employed to induce acute glomerular damage and to model glomerular disease. For this reason, we generated kidney organoids from three iPSC lines and treated these with PAN in order to induce kidney injury. Morphological observations revealed the disruption of glomerular and tubular structures within the kidney organoids upon PAN treatment, which were confirmed by transcriptome analyses. Subsequent analyses revealed an upregulation of immune response as well as inflammatory and cell-death-related processes. We conclude that the treatment of iPSC-derived kidney organoids with PAN induces kidney injury mediated by an intertwined network of inflammation, cytoskeletal re-arrangement, DNA damage, apoptosis and cell death. Furthermore, urine-stem-cell-derived kidney organoids can be used to model kidney-associated diseases and drug discovery.

Cardiovascular, Lymphatic, and Ocular Health in Space.

Life on Earth has evolved continuously under Earth’s 1 G force and the protection of the magnetosphere. Thus, astronauts exhibit maladaptive physiological responses during space travel. Exposure to harmful cosmic radiation and weightlessness are unique conditions to the deep-space environment responsible for several spaceflight-associated risks: visual impairment, immune dysfunction, and cancer due to cosmic radiation in astronauts. The evidence thus reviewed indicates that microgravity and cosmic radiation have deleterious effects on the cardiovascular, lymphatic, and vision systems of astronauts on long-duration space missions. The mechanisms responsible for the decline in these systems are potentially due to cytoskeletal filament rearrangement, endothelial dysfunction, and muscular atrophy. These factors may alter fluid hemodynamics within cardiovascular and lymphatic vasculatures such that greater fluid filtration causes facial and intracranial edema. Thus, microgravity induces cephalad fluid shifts contributing to spaceflight-associated neuro-ocular syndrome (SANS). Moreover, visual impairment via retinal ischemia and altered nitric oxide production may alter endothelial function. Based on rodent studies, cosmic radiation may exacerbate the effects of microgravity as observed in impaired endothelium and altered immunity. Relevant findings help understand the extent of these risks associated with spaceflight and suggest relevant countermeasures to protect astronaut health during deep-space missions.

Biochemical investigation of the impact of Zcl278 on Cdc42/Ack interaction

The Ras superfamily of small G proteins are involved in cell-signaling processes that, ifnot regulated, can lead to disordered cell multiplication, apoptosis inhibition, and tumorigenesis.They function as molecular switches, which through a GTP/GDP exchange cycle, switch on(GTP-bound) or off (GDP-bound) cellular activities. Overexpression of these proteins has beenlinked to many diseases including various cancers. Cdc42, a member of the Rho subfamily ofRas superfamily of small G proteins, participates in the regulation of many cellular processesincluding cell adhesion, mitosis, and cytoskeletal rearrangements.

Mercury impairs human primary endometrial stromal cell function†.

Heavy metal exposures could compromise endometrial cells. Although studies assessed mercury toxicity in cell lines, limited data are available on the concentration of mercury that damage human endometrial stromal cells (hEnSCs) and alter endometrial function. This research aims to study the effects of mercury exposure on cell viability and functional features of hEnSCs. Primary hEnSCs were isolated from 23 endometrial biopsies obtained from healthy donors. After in vitro mercury exposure cell viability of hEnSCs was evaluated via tetrazolium salt metabolism and oxidative stress was assessed by 2', 7'-dichlorofluorescin diacetate assay. hEnSCs were decidualized in vitro in the presence of mercury (0, 25, 50, 75, 250, and 350 nM). Decidualization was evaluated based on prolactin and insulin-like growth factor-binding protein (IGFBP1) secretion and cytoskeletal rearrangement (F-actin staining). Cell proliferation and apoptosis were evaluated by Ki67 immunostaining and TUNEL assay. Mercury doses of 250 nM (P = 0.028) and 500 nM (P = 0.026) increased reactive oxygen species production in hEnSCs after 24 h. Cell viability significantly decreased after 48 h and 72 h (P < 0.05) of mercury exposure at 500 nM. After in vitro decidualization and mercury treatment, decidual hEnSCs showed a dose-dependent decrease in prolactin and IGFBP1 secretion, particularly at 350 nM (P = 0.016). Cell proliferation was decreased in hEnSCs treated with 350 nM mercury (P < 0.001); an increase in apoptosis followed a dose-dependent trend in non-decidual and decidual hEnSCs. These findings support that mercury-induced damage could be due to an increase in ROS production.

NIPEP-IBD; A SYNTHETIC PEPTIDE TARGETING NOVEL MOLECULE, INTEGRIN BETA 1, TO RESTITUTE INTESTINAL EPITHELIAL CELLS FOR INFLAMMATORY BOWEL DISEASE (IBD) TREATMENT

Abstract Under Inflammatory bowel disease (IBD), impaired intestinal barrier from lumen is highly associated with ongoing IBD symptoms and it also contributes as a precursor for IBD. Current IBD therapeutics lack on mucosal regeneration, which the unmet needs could be the next first in class therapeutics for IBD. Here, we propose NIPEP-IBD, a synthetically modified peptide that promotes adhesion, migration, and differentiation of intestinal epithelial cells via interaction of integrin beta 1. From NIBEC’s specialized peptide discovery platform screening, specifically sequenced peptide has been selected for regenerative functional peptide, termed NIPEP-IBD. NIPEP-IBD selectively targeted and bound to integrin beta 1 protein, and its interaction was also verified in vitro, using immunoprecipitation and immunofluorescence assays on epithelial cells. Consequently, NIPEP-IBD increased integrin beta 1 expression, followed by phosphorylated FAK and RhoA proteins. As FAK-RhoA signaling pathway is known to modulate cytoskeletal rearrangement and maturation of epithelial cells, tight junction markers and rapid wound closure of epithelial cells was accelerated by NIPEP-IBD induction. The effect of NIPEP-IBD was further analyzed in vivo IBD model. DSS-induced colitis mouse model was used to analyze therapeutic effect of NIPEP-IBD in each IP and PO administration, and impaired mucosa layer by DSS was recovered by NIPEP-IBD, verified with H&amp;E staining. Moreover, NIPEP-IBD treated mice showed reduced immune cell infiltration in colon tissue and reduced pro-inflammatory cytokines in plasma. In vivo fluorescence imaging system was further used to track distribution of NIPEP-IBD, and NIPEP-IBD specifically binds to impaired epithelium, co-localized with integrin beta 1 protein. The following GLP toxicity studies, ADME studies, and PK studies demonstrated that safety of NIPEP-IBD was verified as a therapeutic agent. Therefore, NIPEP-IBD is a safe and effective therapeutic peptide on IBD patients by restituting epithelial layer of colon and maintain its remission.

LPS induces pulmonary microvascular endothelial cell barrier dysfunction by upregulating ceramide production

The specific role of ceramides in pulmonary microvascular endothelial cell (PMVEC) barrier dysfunction remains unclear. In the present study, pretreatment with pan-caspase inhibitors significantly reduced LPS-induced PMVEC apoptosis and helped to stimulate PMVEC barrier reconstruction after 12 h but had no effect on PMVEC barrier dysfunction in the first 8 h. Further studies showed that imipramine, an acid sphingomyelinase (ASMase) inhibitor, significantly inhibited LPS-induced barrier dysfunction, while an siRNA targeting serine palmityl transferase subunit 1 (SPTLC1) and the pharmacological inhibitor myriocin did not inhibit early acute barrier dysfunction but significantly inhibited PMVEC apoptosis and apoptosis-dependent delayed barrier dysfunction. In addition, LPS was shown to activate RhoA by inducing transient receptor potential channel 6 (TRPC6) overexpression and calcium influx through the ASMase/ceramide pathway, and activation of RhoA further induced the cytoskeletal rearrangement of PMVECs and destruction of intercellular junctions, ultimately leading to early acute PMVEC barrier dysfunction. However, regarding apoptosis-dependent delayed barrier dysfunction, the ceramide-induced de novo synthesis pathway in paracellular cells induced the apoptosis of PMVECs, in which Txnip overexpression inhibited Trx activity and subsequently activated ASK1 in the context of LPS-induced PMVEC apoptosis, acting upstream of the ceramide-induced activation of p38 MAPK and JNK. At the same time, in rats with LPS- or exogenous C8 ceramide-induced ALI, ceramide was demonstrated to play an important role in lung injury by inducing the Txnip/TRX/ASK1/P38 and JNK pathways. Thus, the Txnip/TRX/ASK1/p38 and JNK pathways might be involved in ceramide-mediated PMVEC apoptosis in LPS-induced ALI.

NIPEP-IBD; A SYNTHETIC PEPTIDE TARGETING NOVEL MOLECULE, INTEGRIN BETA 1, TO RESTITUTE INTESTINAL EPITHELIAL CELLS FOR INFLAMMATORY BOWEL DISEASE (IBD) TREATMENT

Under Inflammatory bowel disease (IBD), impaired intestinal barrier from lumen is highly associated with ongoing IBD symptoms and it also contributes as a precursor for IBD. Current IBD therapeutics lack on mucosal regeneration, which the unmet needs could be the next first in class therapeutics for IBD. Here, we propose NIPEP-IBD, a synthetically modified peptide that promotes adhesion, migration, and differentiation of intestinal epithelial cells via interaction of integrin beta 1. From NIBEC’s specialized peptide discovery platform screening, specifically sequenced peptide has been selected for regenerative functional peptide, termed NIPEP-IBD. NIPEP-IBD selectively targeted and bound to integrin beta 1 protein, and its interaction was also verified in vitro, using immunoprecipitation and immunofluorescence assays on epithelial cells. Consequently, NIPEP-IBD increased integrin beta 1 expression, followed by phosphorylated FAK and RhoA proteins. As FAK-RhoA signaling pathway is known to modulate cytoskeletal rearrangement and maturation of epithelial cells, tight junction markers and rapid wound closure of epithelial cells was accelerated by NIPEP-IBD induction. The effect of NIPEP-IBD was further analyzed in vivo IBD model. DSS-induced colitis mouse model was used to analyze therapeutic effect of NIPEP-IBD in each IP and PO administration, and impaired mucosa layer by DSS was recovered by NIPEP-IBD, verified with H&E staining. Moreover, NIPEP-IBD treated mice showed reduced immune cell infiltration in colon tissue and reduced pro-inflammatory cytokines in plasma. In vivo fluorescence imaging system was further used to track distribution of NIPEP-IBD, and NIPEP-IBD specifically binds to impaired epithelium, co-localized with integrin beta 1 protein. The following GLP toxicity studies, ADME studies, and PK studies demonstrated that safety of NIPEP-IBD was verified as a therapeutic agent. Therefore, NIPEP-IBD is a safe and effective therapeutic peptide on IBD patients by restituting epithelial layer of colon and maintain its remission.

Calponin 1 contributes to myofibroblast differentiation of human pleural mesothelial cells.

Pleural mesothelial cells (PMCs) can become myofibroblasts via mesothelial-mesenchymal transition (MesoMT) and contribute to pleural organization, fibrosis, and rind formation. However, how these transformed mesothelial cells contribute to lung fibrosis remains unclear. Here, we investigated the mechanism of contractile myofibroblast differentiation of PMCs. Transforming growth factor-β (TGF-β) induced marked upregulation of calponin 1 expression, which was correlated with notable cytoskeletal rearrangement in human PMCs (HPMCs) to produce stress fibers. Downregulation of calponin 1 expression reduced stress fiber formation. Interestingly, induced stress fibers predominantly contain α-smooth muscle actin (αSMA) associated with calponin 1 but not β-actin. Calponin 1-associated stress fibers also contained myosin II and α-actinin. Furthermore, focal adhesions were aligned with the produced stress fibers. These results suggest that calponin 1 facilitates formation of stress fibers that resemble contractile myofibrils. Supporting this notion, TGF-β significantly increased the contractile activity of HPMCs, an effect that was abolished by downregulation of calponin 1 expression. We infer that differentiation of HPMCs to contractile myofibroblasts facilitates stiffness of scar tissue in pleura to promote pleural fibrosis (PF) and that upregulation of calponin 1 plays a central role in this process.

Prediction and validation of host-pathogen interactions by a versatile inference approach using Aspergillus fumigatus as a case study

Biological networks are characterized by diverse interactions and dynamics in time and space. Many regulatory modules operate in parallel and are interconnected with each other. Some pathways are functionally known and annotated accordingly, e.g., endocytosis, migration, or cytoskeletal rearrangement. However, many interactions are not so well characterized. For reconstructing the biological complexity in cellular networks, we combine here existing experimentally confirmed and analyzed interactions with a protein-interaction inference framework using as basis experimentally confirmed interactions from other organisms. Prediction scoring includes sequence similarity, evolutionary conservation of interactions, the coexistence of interactions in the same pathway, orthology as well as structure similarity to rank and compare inferred interactions. We exemplify our inference method by studying host-pathogen interactions during infection of Mus musculus (phagolysosomes in alveolar macrophages) with Aspergillus fumigatus (conidia, airborne, asexual spores). Three of nine predicted critical host-pathogen interactions could even be confirmed by direct experiments. Moreover, we suggest drugs that manipulate the host-pathogen interaction.

Rab31 promotes the invasion and metastasis of cervical cancer cells by inhibiting MAPK6 degradation.

Persistent infection with high-risk human papillomavirus (HPV) is the main risk factor for cervical cancer. Our mass spectrometry data showed that the Ras-associated binding protein Rab31 was upregulated by HPV; however, little is known regarding the role of Rab31 in the metastasis of cervical cancer cells. In this study, we showed that Rab31 was highly expressed in cervical cancer tissues and cells, and both HPV E6 and E7 promoted the expression of Rab31. Rab31 knockdown inhibited while Rab31 overexpression promoted the migration and invasion capabilities of cervical cancer cells. Additionally, Rab31 knockdown inhibited the epithelial-mesenchymal transition (EMT) and cytoskeletal rearrangement in cervical cancer cells. Furthermore, Rab31 interacted with mitogen-activated protein kinase 6 (MAPK6), and Rab31 knockdown inhibited the expression of MAPK6, which was mainly localized in the cytoplasm. More importantly, Rab31 knockdown promoted and Rab31 overexpression inhibited MAPK6 degradation. Accordingly, MAPK6 overexpression restored the decreased migration potential caused by Rab31 knockdown. Finally, a xenograft mouse model showed that Rab31 knockdown in cervical cancer cells led to reduced tumor growth and impaired lung and liver metastasis in vivo. In conclusion, Rab31 plays a crucial role in cervical cancer metastasis by inhibiting MAPK6 degradation. Thus, Rab31 may serve as a novel therapeutic target to manage cervical cancer.

Apigenin regulates the migration, invasion, and autophagy of hepatocellular carcinoma cells by downregulating YAP.

Apigenin is an edible flavonoid with anticancer properties; however, the underlying mechanisms in hepatocellular carcinoma (HCC) remain to be clarified. In the present study, we demonstrated that apigenin decreased the viability of both SMMC-7721 and SK-Hep1 cells in a dose-dependent manner, and inhibited the migration and invasion of HCC cells with different metastatic potential by regulating actin cytoskeletal rearrangements. Moreover, we showed that apigenin decreased the expression of YAP, and subsequently reduced migration and invasion by modulating the expression of the epithelial-mesenchymal transition (EMT) markers, and promoted the autophagy of HCC cells by regulating the expression of autophagy-related genes. Collectively, the present findings might provide a novel mechanism for the therapeutic application of apigenin in HCC.

Cortactin Promotes Effective AGS Cell Scattering by Helicobacter pylori CagA, but Not Cellular Vacuolization and Apoptosis Induced by the Vacuolating Cytotoxin VacA.

Cortactin is an actin-binding protein and actin-nucleation promoting factor regulating cytoskeletal rearrangements in eukaryotes. Helicobacter pylori is a gastric pathogen that exploits cortactin to its own benefit. During infection of gastric epithelial cells, H. pylori hijacks multiple cellular signaling pathways, leading to the disruption of key cell functions. Two bacterial virulence factors play important roles in this scenario, the vacuolating cytotoxin VacA and the translocated effector protein CagA of the cag type IV secretion system (T4SS). Specifically, by overruling the phosphorylation status of cortactin, H. pylori alternates the activity of molecular interaction partners of this important protein, thereby manipulating the performance of cytoskeletal rearrangements, endosomal trafficking and cell movement. Based on shRNA knockdown and other studies, it was previously reported that VacA utilizes cortactin for its cellular uptake, intracellular travel and induction of apoptosis by a mitochondria-dependent mechanism, while CagA induces cell scattering, motility and elongation. To investigate the role of cortactin in these phenotypes in more detail, we produced a complete knockout mutant of cortactin in the gastric adenocarcinoma cell line AGS by CRISPR-Cas9. These cells were infected with H. pylori wild-type or various isogenic mutant strains. Unexpectedly, cortactin deficiency did not prevent the uptake and formation of VacA-dependent vacuoles, nor the induction of apoptosis by internalized VacA, while the induction of T4SS- and CagA-dependent AGS cell movement and elongation were strongly reduced. Thus, we provide evidence that cortactin is required for the function of internalized CagA, but not VacA.

AUTS2 Gene: Keys to Understanding the Pathogenesis of Neurodevelopmental Disorders.

Neurodevelopmental disorders (NDDs), including autism spectrum disorders (ASD) and intellectual disability (ID), are a large group of neuropsychiatric illnesses that occur during early brain development, resulting in a broad spectrum of syndromes affecting cognition, sociability, and sensory and motor functions. Despite progress in the discovery of various genetic risk factors thanks to the development of novel genomics technologies, the precise pathological mechanisms underlying the onset of NDDs remain elusive owing to the profound genetic and phenotypic heterogeneity of these conditions. Autism susceptibility candidate 2 (AUTS2) has emerged as a crucial gene associated with a wide range of neuropsychological disorders, such as ASD, ID, schizophrenia, and epilepsy. AUTS2 has been shown to be involved in multiple neurodevelopmental processes; in cell nuclei, it acts as a key transcriptional regulator in neurodevelopment, whereas in the cytoplasm, it participates in cerebral corticogenesis, including neuronal migration and neuritogenesis, through the control of cytoskeletal rearrangements. Postnatally, AUTS2 regulates the number of excitatory synapses to maintain the balance between excitation and inhibition in neural circuits. In this review, we summarize the knowledge regarding AUTS2, including its molecular and cellular functions in neurodevelopment, its genetics, and its role in behaviors.

Scaffold polarity proteins Par3A and Par3B share redundant functions while Par3B acts independent of atypical protein kinase C/Par6 in podocytes to maintain the kidney filtration barrier

Glomerular diseases are a major cause for chronic kidney disorders. In most cases podocyte injury is causative for disease development. Cytoskeletal rearrangements and morphological changes are hallmark features of podocyte injury and result in dedifferentiation and loss of podocytes. Here, we establish a link between the Par3 polarity complex and actin regulators necessary to establish and maintain podocyte architecture by utilizing mouse and Drosophila models to characterize the functional role of Par3A and Par3B and its fly homologue Bazooka invivo. Only simultaneous inactivation of both Par3 proteins caused a severe disease phenotype. Rescue experiments in Drosophila nephrocytes revealed atypical protein kinase C (aPKC)-Par6 dependent and independent effects. While Par3A primarily acts via aPKC-Par6, Par3B function was independent of Par6. Actin-associated synaptopodin protein levels were found to be significantly upregulated upon loss of Par3A/B in mouse podocytes. Tropomyosin2, which shares functional similarities with synaptopodin, was also elevated in Bazooka depleted nephrocytes. The simultaneous depletion of Bazooka and Tropomyosin2 resulted in a partial rescue of the Bazooka knockdown phenotype and prevented increased Rho1-GTP, a member of a GTPase protein family regulating the cytoskeleton. The latter contribute to the nephrocyte phenotype observed upon loss of Bazooka. Thus, we demonstrate that Par3 proteins share a high functional redundancy but also have specific functions. Par3A acts in an aPKC-Par6 dependent way and regulates RhoA-GTP levels, while Par3B exploits Par6 independent functions influencing synaptopodin localization. Hence, Par3A and Par3B link elements of polarity signaling and actin regulators to maintain podocyte architecture.

GSK3β Activity in Reward Circuit Functioning and Addiction

Glycogen synthase kinase-3β (GSK3β), primarily described as a regulator of glycogen metabolism, is a molecular hub linking numerous signaling pathways and regulates many cellular processes like cytoskeletal rearrangement, cell migration, apoptosis, and proliferation. In neurons, the kinase is engaged in molecular events related to the strengthening and weakening of synapses, which is a subcellular manifestation of neuroplasticity. Dysregulation of GSK3β activity has been reported in many neuropsychiatric conditions, like schizophrenia, major depressive disorder, bipolar disorder, and Alzheimer’s disease. In this review, we describe the kinase action in reward circuit-related structures in health and disease. The effect of pharmaceuticals used in the treatment of addiction in the context of GSK3β activity is also discussed.

Excitatory neurotransmission activates compartmentalized calcium transients in Müller glia without affecting lateral process motility.

Neural activity has been implicated in the motility and outgrowth of glial cell processes throughout the central nervous system. Here, we explore this phenomenon in Müller glia, which are specialized radial astroglia that are the predominant glial type of the vertebrate retina. Müller glia extend fine filopodia-like processes into retinal synaptic layers, in similar fashion to brain astrocytes and radial glia that exhibit perisynaptic processes. Using two-photon volumetric imaging, we found that during the second postnatal week, Müller glial processes were highly dynamic, with rapid extensions and retractions that were mediated by cytoskeletal rearrangements. During this same stage of development, retinal waves led to increases in cytosolic calcium within Müller glial lateral processes and stalks. These regions comprised distinct calcium compartments, distinguished by variable participation in waves, timing, and sensitivity to an M1 muscarinic acetylcholine receptor antagonist. However, we found that motility of lateral processes was unaffected by the presence of pharmacological agents that enhanced or blocked wave-associated calcium transients. Finally, we found that mice lacking normal cholinergic waves in the first postnatal week also exhibited normal Müller glial process morphology. Hence, outgrowth of Müller glial lateral processes into synaptic layers is determined by factors that are independent of neuronal activity.

The Antioxidant Phytochemical Schisandrin A Promotes Neural Cell Proliferation and Differentiation after Ischemic Brain Injury.

Schisandrin A (SCH) is a natural bioactive phytonutrient that belongs to the lignan derivatives found in Schisandra chinensis fruit. This study aims to investigate the impact of SCH on promoting neural progenitor cell (NPC) regeneration for avoiding stroke ischemic injury. The promoting effect of SCH on NPCs was evaluated by photothrombotic model, immunofluorescence, cell line culture of NPCs, and Western blot assay. The results showed that neuron-specific class III beta-tubulin (Tuj1) was positive with Map2 positive nerve fibers in the ischemic area after using SCH. In addition, Nestin and SOX2 positive NPCs were significantly (p < 0.05) increased in the penumbra and core. Further analysis identified that SCH can regulate the expression level of cell division control protein 42 (Cdc42). In conclusion, our findings suggest that SCH enhanced NPCs proliferation and differentiation possible by Cdc42 to regulated cytoskeletal rearrangement and polarization of cells, which provides new hope for the late recovery of stroke.

A MEKK1 - JNK mitogen activated kinase (MAPK) cascade module is active in Echinococcus multilocularis stem cells.

The metacestode larval stage of the fox-tapeworm Echinococcus multilocularis causes alveolar echinococcosis by tumour-like growth within the liver of the intermediate host. Metacestode growth and development is stimulated by host-derived cytokines such as insulin, fibroblast growth factor, and epidermal growth factor via activation of cognate receptor tyrosine kinases expressed by the parasite. Little is known, however, concerning signal transmission to the parasite nucleus and cross-reaction with other parasite signalling systems. Using bioinformatic approaches, cloning, and yeast two-hybrid analyses we identified a novel mitogen-activated kinase (MAPK) cascade module that consists of E. multilocularis orthologs of the tyrosine kinase receptor interactor Growth factor receptor-bound 2, EmGrb2, the MAPK kinase kinase EmMEKK1, a novel MAPK kinase, EmMKK3, and a close homolog to c-Jun N-terminal kinase (JNK), EmMPK3. Whole mount in situ hybridization analyses indicated that EmMEKK1 and EmMPK3 are both expressed in E. multilocularis germinative (stem) cells but also in differentiated or differentiating cells. Treatment with the known JNK inhibitor SP600125 led to a significantly reduced formation of metacestode vesicles from stem cells and to a specific reduction of proliferating stem cells in mature metacestode vesicles. We provide evidence for the expression of a MEKK1-JNK MAPK cascade module which, in mammals, is crucially involved in stress responses, cytoskeletal rearrangements, and apoptosis, in E. multilocularis stem cells. Inhibitor studies indicate an important role of JNK signalling in E. multilocularis stem cell survival and/or maintenance. Our data are relevant for molecular and cellular studies into crosstalk signalling mechanisms that govern Echinococcus stem cell function and introduce the JNK signalling cascade as a possible target of chemotherapeutics against echinococcosis.

α4/α9 Integrins Coordinate Epithelial Cell Migration Through Local Suppression of MAP Kinase Signaling Pathways.

Adhesion of basal keratinocytes to the underlying extracellular matrix (ECM) plays a key role in the control of skin homeostasis and response to injury. Integrin receptors indirectly link the ECM to the cell cytoskeleton through large protein complexes called focal adhesions (FA). FA also function as intracellular biochemical signaling platforms to enable cells to respond to changing extracellular cues. The α4β1 and α9β1 integrins are both expressed in basal keratinocytes, share some common ECM ligands, and have been shown to promote wound healing in vitro and in vivo. However, their roles in maintaining epidermal homeostasis and relative contributions to pathological processes in the skin remain unclear. We found that α4β1 and α9β1 occupied distinct regions in monolayers of a basal keratinocyte cell line (NEB-1). During collective cell migration (CCM), α4 and α9 integrins co-localized along the leading edge. Pharmacological inhibition of α4β1 and α9β1 integrins increased keratinocyte proliferation and induced a dramatic change in cytoskeletal remodeling and FA rearrangement, detrimentally affecting CCM. Further analysis revealed that α4β1/α9β1 integrins suppress extracellular signal-regulated kinase (ERK1/2) activity to control migration through the regulation of downstream kinases including Mitogen and Stress Activated Kinase 1 (MSK1). This work demonstrates the roles of α4β1 and α9β1 in regulating migration in response to damage cues.

Kinase play-off on lipid turf hints at a molecular basis for new-found tumor-suppressor activity of PKCs

Migration of cells mediates key life processes starting from the beginning of life, through development and adulthood (1). This essential process is a teleological culmination of a complex molecular circuitry that generates signals that propagate like waves to orchestrate cytoskeletal rearrangements necessary for cell motion. To set the stage for discussing the role of kinases, which are proteins that transfer phosphate moieties to bio-molecular substrates, and are putative “star” players in cell migration, let us attempt to create a simplistic mental sketch of this intricate molecular interplay.