The control of cell motility and epithelial morphogenesis by Jun kinases

The lincRNA JUNI regulates the stress-dependent induction of c-Jun, cellular migration and survival through the modulation of the DUSP14-JNK axis

Cancer cells employ adaptive mechanisms to survive various stressors, including genotoxic drugs. Understanding the factors promoting survival is crucial for developing effective treatments. In this study, we unveil a previously unexplored long non-coding RNA, JUNI (JUN-DT, LINC01135), which is upregulated by genotoxic drugs through the activation of stress-activated MAPKs, JNK, and p38 and consequently exerts positive control over the expression of its adjacent gene product c-Jun, a well-known oncoprotein, which transduces signals to multiple transcriptional outputs. JUNI regulates cellular migration and has a crucial role in conferring cellular resistance to chemotherapeutic drugs or UV radiation. Depletion of JUNI markedly increases the sensitivity of cultured cells and spheroids to chemotherapeutic agents. We identified 57 proteins interacting with JUNI. The activity of one of them the MAPK phosphatase and inhibitor, DUSP14, is counteracted by JUNI, thereby, facilitating efficient JNK phosphorylation and c-Jun induction when cells are exposed to UV radiation. The antagonistic interplay with DUSP14 contributes not only to c-Jun induction but also augments the survival of UV-exposed cells. In summary, we introduce JUNI as a novel stress-inducible regulator of c-Jun, positioning it as a potential target for enhancing the sensitivity of cancer cells to chemotherapy.

Low-intensity pulsed ultrasound of different intensities differently affects myocardial ischemia/reperfusion injury by modulating cardiac oxidative stress and inflammatory reaction

Introduction

The prevalence of ischemic heart disease has reached pandemic levels worldwide. Early revascularization is currently the most effective therapy for ischemic heart diseases but paradoxically induces myocardial ischemia/reperfusion (MI/R) injury. Cardiac inflammatory reaction and oxidative stress are primarily involved in the pathology of MI/R injury. Low-intensity pulsed ultrasound (LIPUS) has been demonstrated to reduce cell injury by protecting against inflammatory reaction and oxidative stress in many diseases, including cardiovascular diseases, but rarely on MI/R injury.

Methods

This study was designed to clarify whether LIPUS alleviates MI/R injury by alleviating inflammatory reaction and oxidative stress. Simultaneously, we have also tried to confirm which intensity of the LIPUS might be more suitable to ameliorate the MI/R injury, as well as to clarify the signaling mechanisms. MI/R and simulated ischemia/reperfusion (SI/R) were respectively induced in Sprague Dawley rats and human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs). LIPUS treatment, biochemical measurements, cell death assay, estimation of cardiac oxidative stress and inflammatory reaction, and protein detections by western blotting were performed according to the protocol.

Results

In our study, both in vivo and in vitro, LIPUS of 0.1 W/cm2 (LIPUS0.1) and 0.5 W/cm2 (LIPUS0.5) make no significant difference in the cardiomyocytes under normoxic condition. Under the hypoxic condition, MI/R injury, inflammatory reaction, and oxidative stress were partially ameliorated by LIPUS0.5 but were significantly aggravated by LIPUS of 2.5 W/cm2 (LIPUS2.5) both in vivo and in vitro. The activation of the apoptosis signal-regulating kinase 1 (ASK1)/c-Jun N-terminal kinase (JNK) pathway in cardiomyocytes with MI/R injury was partly rectified LIPUS0.5 both in vivo and in vitro.

Conclusion

Our study firstly demonstrated that LIPUS of different intensities differently affects MI/R injury by regulating cardiac inflammatory reaction and oxidative stress. Modulations on the ASK1/JNK pathway are the signaling mechanism by which LIPUS0.5 exerts cardioprotective effects. LIPUS0.5 is promising for clinical translation in protecting against MI/R injury. This will be great welfare for patients suffering from MI/R injury.

Lack of apoptosis leads to cellular senescence and tumorigenesis in Drosophila epithelial cells

Programmed cell death (apoptosis) is a homeostasis program of animal tissues designed to remove cells that are unwanted or are damaged by physiological insults. To assess the functional role of apoptosis, we have studied the consequences of subjecting Drosophila epithelial cells defective in apoptosis to stress or genetic perturbations that normally cause massive cell death. We find that many of those cells acquire persistent activity of the JNK pathway, which drives them into senescent status, characterized by arrest of cell division, cell hypertrophy, Senescent Associated ß-gal activity (SA-ß-gal), reactive oxygen species (ROS) production, Senescent Associated Secretory Phenotype (SASP) and migratory behaviour. We have identified two classes of senescent cells in the wing disc: 1) those that localize to the appendage part of the disc, express the upd, wg and dpp signalling genes and generate tumour overgrowths, and 2) those located in the thoracic region do not express wg and dpp nor they induce tumour overgrowths. Whether to become tumorigenic or non-tumorigenic depends on the original identity of the cell prior to the transformation. We also find that the p53 gene contributes to senescence by enhancing the activity of JNK.

Analysis of the Anti-Tumour Effect of Xuefu Zhuyu Decoction Based on Network Pharmacology and Experimental Verification in Drosophila

Background: Tumours are among the most lethal diseases that heavily endanger human health globally. Xuefu Zhuyu Decoction (XFZYD) is a prescription used to treat blood-activating stasis. Although XFZYD has been shown to suppress migration and invasion of tumour cells, the active ingredients, potential targets, and underlying mechanism remain largely elusive. Purpose: To identify the prospective ingredients and major targets of XFZYD against tumours, and evaluate the efficacy and potential molecular mechanisms of XFZYD extract on tumour growth and invasion. Methods: We predicted that XFZYD might act on 80 targets through 128 active components using the network pharmacology analysis method. In addition, we prepared an XFZYD aqueous extract and employed the RasV12/lgl -/- -induced Drosophila tumour model to carry out experimental verification. Results: XFZYD did not exhibit any side effects on development, viability, and fertility. Furthermore, XFZYD significantly impeded tumour size and invasion at moderate concentrations and suppressed the increased phosphorylation of JNK but strongly enhanced the expression of Caspase 3 in the RasV12/lgl -/- model. Finally, the mRNA level of the transcription complex AP-1 component c-FOS was remarkably reduced. In contrast, the transcription of three pro-apoptotic genes was significantly increased when XFZYD was used to treat the tumour model. Conclusion: The study findings suggest that XFZYD may promote tumour cell apoptosis by activating caspase signalling to control primary growth and hinder tumour cell invasion by suppressing JNK/AP-1 signalling activity, thus providing a potential therapeutic strategy for XFZYD in the clinical treatment of cancer and other related diseases.

SUMOylation of Jun fine-tunes the Drosophila gut immune response

Post-translational modification by the small ubiquitin-like modifier, SUMO can modulate the activity of its conjugated proteins in a plethora of cellular contexts. The effect of SUMO conjugation of proteins during an immune response is poorly understood in Drosophila. We have previously identified that the transcription factor Jra, the Drosophila Jun ortholog and a member of the AP-1 complex is one such SUMO target. Here, we find that Jra is a regulator of the Pseudomonas entomophila induced gut immune gene regulatory network, modulating the expression of a few thousand genes, as measured by quantitative RNA sequencing. Decrease in Jra in gut enterocytes is protective, suggesting that reduction of Jra signaling favors the host over the pathogen. In Jra, lysines 29 and 190 are SUMO conjugation targets, with the Jra^K29R+K190R double mutant being SUMO conjugation resistant (SCR). Interestingly, a Jra^SCR fly line, generated by CRISPR/Cas9 based genome editing, is more sensitive to infection, with adults showing a weakened host response and increased proliferation of Pseudomonas. Transcriptome analysis of the guts of Jra^SCR and Jra^WT flies suggests that lack of SUMOylation of Jra significantly changes core elements of the immune gene regulatory network, which include antimicrobial agents, secreted ligands, feedback regulators, and transcription factors. Mechanistically, SUMOylation attenuates Jra activity, with the TFs, forkhead, anterior open, activating transcription factor 3 and the master immune regulator Relish being important transcriptional targets. Our study implicates Jra as a major immune regulator, with dynamic SUMO conjugation/deconjugation of Jra modulating the kinetics of the gut immune response.

The intestine has a resident population of commensal microorganisms against which the immune machinery is tuned to show low or no reactivity. In contrast, when pathogenic microorganisms are ingested, the gut responds by activating signaling cascades that lead to the killing and clearance of the pathogen. In this study, we examine the role played by the well-known transcription factor Jun in regulating the immune response in the Drosophila gut. We find that loss of Jun leads to the change in intensity and kinetics of the gut immune transcriptome. The transcriptional profile indicates a stronger response when Jun activity is reduced. Also, animals infected with Pseudomonas entomophila live longer when Jun signaling is reduced. Further, we find that Jun is post-translationally modified on Lys29 and Lys190 by SUMO. To understand the effect of SUMO-conjugation of Jun, we create by state-of-the-art CRISPR/Cas9 genome editing a Drosophila line where Jun is resistant to SUMOylation. This line is more sensitive to infection, with a weaker host-defense response. Our data suggest that Jun Signaling favors the pathogen by dampening the immune response. SUMO conjugation of Jun reverses the dampening and strengthens the immune response in favor of the host. Dynamic SUMOylation of Jun thus fine-tunes the gut immune response to pathogens.

Low-Intensity Focused Ultrasound Stimulation Ameliorates Working Memory Dysfunctions in Vascular Dementia Rats via Improving Neuronal Environment

Working memory impairment is one of the remarkable cognitive dysfunctions induced by vascular dementia (VD), and it is necessary to explore an effective treatment. Recently, low-intensity focused ultrasound stimulation (LIFUS) has been found notable neuroprotective effects on some neurological diseases, including VD. However, whether it could ameliorate VD-induced working memory impairment was still not been clarified. The purpose of this study was to address this issue and the underlying mechanism. We established VD rat model using the bilateral common carotid artery occlusion (BCCAO) and applied the LIFUS (center frequency = 0.5 MHz; I_spta = 500 mW/cm², 10 mins/day) to bilateral medial prefrontal cortex (mPFC) for 2 weeks since 2 weeks after the surgery. The main results showed that the LIFUS could significantly improve the performance of VD rats in the specific working memory tasks (delayed nonmatch-to-sample task and step-down task), which might be associated with the improved synaptic function. We also found the improvement in the cerebral blood flow (CBF) and reduced neuroinflammation in mPFC after LIFUS treatment indicated by the inhibition of Toll-like receptor (TLR4)/nuclear factor kappa B (NF-κB) pathway and the decrease of proinflammatory cytokines. The amelioration of CBF and neuroinflammation may promote the living environment of the neurons in VD which then contribute to the survival of neurons and the improvement in synaptic function. Taken together, our findings indicate that LIFUS targeted mPFC can effectively ameliorate reward-based spatial working memory and fear working memory dysfunctions induced by VD via restoring the living environment, survivability, and synaptic functions of the neurons in mPFC of VD rats. This study adds to the evidence that LIFUS could become a promising and non-invasive treatment strategy for the clinical treatment of central nervous system diseases related to cognitive impairments in the future.

Dissection of the Regulatory Elements of the Complex Expression Pattern of Puckered, a Dual-Specificity JNK Phosphatase

For developmental processes, we know most of the gene networks controlling specific cell responses. We still have to determine how these networks cooperate and how signals become integrated. The JNK pathway is one of the key elements modulating cellular responses during development. Yet, we still know little about how the core components of the pathway interact with additional regulators or how this network modulates cellular responses in the whole organism in homeostasis or during tissue morphogenesis. We have performed a promoter analysis, searching for potential regulatory sequences of puckered (puc) and identified different specific enhancers directing gene expression in different tissues and at different developmental times. Remarkably, some of these domains respond to the JNK activity, but not all. Altogether, these analyses show that puc expression regulation is very complex and that JNK activities participate in non-previously known processes during the development of Drosophila.

Genomic signatures of the unjamming transition in compressed human bronchial epithelial cells

Epithelial tissue can transition from a jammed, solid-like, quiescent phase to an unjammed, fluid-like, migratory phase, but the underlying molecular events of the unjamming transition (UJT) remain largely unexplored. Using primary human bronchial epithelial cells (HBECs) and one well-defined trigger of the UJT, compression mimicking the mechanical effects of bronchoconstriction, here, we combine RNA sequencing data with protein-protein interaction networks to provide the first genome-wide analysis of the UJT. Our results show that compression induces an early transcriptional activation of the membrane and actomyosin network and a delayed activation of the extracellular matrix (ECM) and cell-matrix networks. This response is associated with a signaling cascade that promotes actin polymerization and cellular motility through the coordinated interplay of downstream pathways including ERK, JNK, integrin signaling, and energy metabolism. Moreover, in nonasthmatic versus asthmatic HBECs, common genomic patterns associated with ECM remodeling suggest a molecular connection between airway remodeling, bronchoconstriction, and the UJT.

Deltex cooperates with TRAF6 to promote apoptosis and cell migration through Eiger-independent JNK activation in Drosophila

JNK signaling is a highly conserved signaling pathway that regulates a broad spectrum of cellular processes including cell proliferation, migration, and apoptosis. In Drosophila, JNK signaling is activated by binding of the tumor necrosis factor (TNF) Eiger to its receptor Wengen, and a conserved signaling cascade operates that culminates into activation of dual phosphatase Puckered thereby triggering apoptosis. The tumor necrosis factor receptor (TNFR) associated factor 6 (TRAF6) is an adaptor protein, which transduces the signal from TNFRs and Toll-like receptor/interleukin-1 receptor superfamily to induce a wide spectrum of cellular responses. TRAF6 also acts as the adaptor protein that mediates Eiger/JNK signaling in Drosophila. In a genetic interaction study, deltex (Dx) was identified as a novel interactor of TRAF6. Dx is well known to regulate Notch signaling in a context-dependent manner. Our data suggest that combinatorial action of Dx and TRAF6 enhances the Dx-induced wing nicking phenotype by inducing caspase-mediated cell death. Co-expression of Dx and TRAF6 also results in enhanced invasive behavior and perturbs the normal morphology of cells. The cooperative action of Dx and TRAF6 is attributed to JNK activation, which also leads to ectopic wingless (Wg) and decapentaplegic (Dpp) expression. Our results also reveal that the endocytic pathway component Rab7 may play a pivotal role in the regulation of Dx-TRAF6-mediated activation of JNK signaling. Here, we present the fact that Dx and TRAF6 together activate JNK signaling in an Eiger-independent mechanism.

Overexpression of Wnt7a enhances radiosensitivity of non-small-cell lung cancer via the Wnt/JNK pathway

The Wingless-type protein 7a (Wnt7a) plays an antiproliferative role in non-small-cell lung cancer (NSCLC). Previous studies have indicated that Wnt7a expression was downregulated in radiation-resistant NSCLC cells. However, little is known about its biological functions and molecular mechanisms in radiosensitivity of NSCLC. Thus, NSCLC cell proliferation and apoptosis in response to Wnt7a overexpression and/or radiation were determined by 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyl-tertazolium bromide (MTT) assay and flow cytometry, respectively. The activation of the Wnt/cJun N-terminal kinase (JNK) and Wnt/β-catenin signaling pathways were further examined by western blot in NSCLC cell lines H1650 and A549. Wnt7a overexpression combined with radiation-inhibited cell proliferation and induced apoptosis in NSCLC cell lines compared to Wnt7a overexpression or radiotherapy alone. In addition, the phosphorylation of JNK, but not β-catenin, was congruent with the changes in Wnt7a overexpression and/or radiation. Moreover, the Wnt/JNK pathway could induce the apoptosis of NSCLC cells through the mitochondrial pathway. Inhibition of the Wnt/JNK signaling pathway by SP600125, a JNK inhibitor, contributed to proliferation induction in NSCLC cells. Taken together, these results showed that Wnt7a overexpression sensitized NSCLC cell lines to radiotherapy through the Wnt/JNK signaling pathway.

Pro-apoptotic and pro-proliferation functions of the JNK pathway of Drosophila: roles in cell competition, tumorigenesis and regeneration

The Jun N-terminal kinase (JNK) is a member of the mitogen-activated protein kinase family. It appears to be conserved in all animal species where it regulates important physiological functions involved in apoptosis, cell migration, cell proliferation and regeneration. In this review, we focus on the functions of JNK in Drosophila imaginal discs, where it has been reported that it can induce both cell death and cell proliferation. We discuss this apparent paradox in the light of recent findings and propose that the pro-apoptotic and the pro-proliferative functions are intrinsic properties of JNK activity. Whether one function or another is predominant depends on the cellular context.

Inducible microRNA-200c decreases motility of breast cancer cells and reduces filamin A

Cancer progression and metastases are frequently related to changes of cell motility. Amongst others, the microRNA-200c (miR-200c) was shown to maintain the epithelial state of cells and to hamper migration. Here, we describe two miR-200c inducible breast cancer cell lines, derived from miR-200c knock-out MCF7 cells as well as from the miR-200c-negative MDA-MB-231 cells and report on the emerging phenotypic effects after miR-200s induction. The induction of miR-200c expression seems to effect a rapid reduction of cell motility, as determined by 1D microlane migration assays. Sustained expression of miR200c leads to a changed morphology and reveals a novel mechanism by which miR-200c interferes with cytoskeletal components. We find that filamin A expression is attenuated by miRNA-200c induced downregulation of the transcription factors c-Jun and MRTF/SRF. This potentially novel pathway that is independent of the prominent ZEB axis could lead to a broader understanding of the role that miR200c plays in cancer metastasis.

Autologous micrograft accelerates endogenous wound healing response through ERK-induced cell migration

Defective cell migration causes delayed wound healing (WH) and chronic skin lesions. Autologous micrograft (AMG) therapies have recently emerged as a new effective and affordable treatment able to improve wound healing capacity. However, the precise molecular mechanism through which AMG exhibits its beneficial effects remains unrevealed. Herein we show that AMG improves skin re-epithelialization by accelerating the migration of fibroblasts and keratinocytes. More specifically, AMG-treated wounds showed improvement of indispensable events associated with successful wound healing such as granulation tissue formation, organized collagen content, and newly formed blood vessels. We demonstrate that AMG is enriched with a pool of WH-associated growth factors that may provide the starting signal for a faster endogenous wound healing response. This work links the increased cell migration rate to the activation of the extracellular signal-regulated kinase (ERK) signaling pathway, which is followed by an increase in matrix metalloproteinase expression and their extracellular enzymatic activity. Overall we reveal the AMG-mediated wound healing transcriptional signature and shed light on the AMG molecular mechanism supporting its potential to trigger a highly improved wound healing process. In this way, we present a framework for future improvements in AMG therapy for skin tissue regeneration applications.

Mitogen-Activated Protein Kinases (MAPKs) and Cholangiocarcinoma: The Missing Link

In recent years, the incidence of both liver and biliary tract cancer has increased. Hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA) are the two most common types of hepatic malignancies. Whereas HCC is the fifth most common malignant tumor in Western countries, the prevalence of CCA has taken an alarming increase from 0.3 to 2.1 cases per 100,000 people. The lack of specific biomarkers makes diagnosis very difficult in the early stages of this fatal cancer. Thus, the prognosis of CCA is dismal and surgery is the only effective treatment, whilst recurrence after resection is common. Even though chemotherapy and radiotherapy may prolong survival in patients with CCA, the 5-year survival rate is still very low—a significant global problem in clinical diagnosis and therapy. The mitogen-activated protein kinase (MAPK) pathway plays an important role in signal transduction by converting extracellular stimuli into a wide range of cellular responses including inflammatory response, stress response, differentiation, survival, and tumorigenesis. Dysregulation of the MAPK cascade involves key signaling components and phosphorylation events that play an important role in tumorigenesis. In this review, we discuss the pathophysiological role of MAPK, current therapeutic options, and the current situation of MAPK-targeted therapies in CCA.

Development of Effective Therapeutics Targeting HER3 for Cancer Treatment

HER3 is the third member of the human epidermal growth factor receptor (HER/EGFR) family, and unlike its other family members, is unique due to its minimal intrinsic kinase activity. As a result, HER3 has to interact with another receptor tyrosine kinase (RTK), such as EGFR or HER2, in order to activate the PI-3 K/Akt, MEK/MAPK, Jak/Stat pathways, as well as Src kinase. Over-expression of HER3 in various human cancers promotes tumor progression by increasing metastatic potential and acting as a major cause of treatment failure. Effective inhibition of HER3, and/or the key downstream mediators of HER3 signaling, is thought to be required to overcome resistance and enhance therapeutic efficacy. To date, there is no known HER3-targeted therapy that is approved for breast cancer, with a number of anti-HER3 antibodies current in various stages of development and clinical testing. Recent data suggests that the epigenetic strategy of using a histone deacetylase (HDAC) inhibitor, or functional cooperative miRNAs, may be an effective way to abrogate HER3 signaling. Here, we summarize the latest advances in our understanding of the mechanism of HER3 signaling in tumor progression, with continuing research towards the identification of therapeutic anti-HER3 antibodies. We will also examine the potential to develop novel epigenetic approaches that specifically target the HER3 receptor, along with important key downstream mediators that are involved in cancer treatment.

Protein oligomerization is the biochemical process highly up-regulated in porcine oocytes before in vitro maturation (IVM)

A wide variety of mechanisms controlling oligomerization are observed. The dynamic nature of protein oligomerization is important for bioactivity control. The oocyte must undergo a series of changes to become a mature form before it can fully participate in the processes associated with its function as a female gamete. The growth of oocytes in the follicular environment is accompanied by surrounding somatic cumulus (CCs) and granulosa cells (GCs). It has been shown that oocytes tested before and after in vitro maturation (IVM) differ significantly in the transcriptomic and proteomic profiles. The aim of this study was to determine new proteomic markers for the oligomerization of porcine oocyte proteins that are associated with cell maturation competence. The Affymetrix microarray assay was performed to examine the gene expression profile associated with protein oligomerization in oocytes before and after IVM. In total, 12258 different transcriptomes were analyzed, of which 419 genes with lower expression in oocytes after IVM. We found 9 genes: GJA1, VCP, JUP, MIF, MAP3K1, INSR, ANGPTL4, EIF2AK3, DECR1, which were significantly down-regulated in oocytes after IVM (in vitro group) compared to oocytes analyzed before IVM (in vivo group). The higher expression of genes involved in the oligomerization of the protein before IVM indicates that they can be recognized as important markers of biological activation of proteins necessary for the further growth and development of pig embryos.

Requirement for and polarized localization of integrin proteins during Drosophila wound closure

Wound reepithelialization is an evolutionarily conserved process in which skin cells migrate as sheets to heal the breach and is critical to prevent infection but impaired in chronic wounds. Integrin heterodimers mediate attachment between epithelia and underlying extracellular matrix and also act in large signaling complexes. The complexity of the mammalian wound environment and evident redundancy among integrins has impeded determination of their specific contributions to reepithelialization. Taking advantage of the genetic tools and smaller number of integrins in Drosophila, we undertook a systematic in vivo analysis of integrin requirements in the reepithelialization of skin wounds in the larva. We identify αPS2-βPS and αPS3-βPS as the crucial integrin dimers and talin as the only integrin adhesion component required for reepithelialization. The integrins rapidly accumulate in a JNK-dependent manner in a few rows of cells surrounding a wound. Intriguingly, the integrins localize to the distal margin in these cells, instead of the frontal or lamellipodial distribution expected for proteins providing traction and recruit nonmuscle myosin II to the same location. These findings indicate that signaling roles of integrins may be important for epithelial polarization around wounds and lay the groundwork for using Drosophila to better understand integrin contributions to reepithelialization.

Understanding the biology of HER3 receptor as a therapeutic target in human cancer

HER3 belongs to the human epidermal growth factor receptor (HER) family which also includes HER1/EGFR/erbB1, HER2/erbB2, and HER4/erbB4. As a unique member of the HER family, HER3 lacks or has little intrinsic tyrosine kinase activity. It frequently co-expresses and forms heterodimers with other receptor tyrosine kinases (RTKs) in cancer cells to activate oncogenic signaling, especially the PI-3K/Akt pathway and Src kinase. Elevated expression of HER3 has been observed in a wide variety of human cancers and associates with a worse survival in cancer patients with solid tumors. Studies on the underlying mechanism implicate HER3 expression as a major cause of treatment failure in cancer therapy. Activation of HER3 signaling has also been shown to promote cancer metastasis. These data strongly support the notion that therapeutic inactivation of HER3 and/or its downstream signaling is required to overcome treatment resistance and improve the outcomes of cancer patients.

Repression of MAP3K1 expression and JNK activity by canonical Wnt signaling

Morphogenesis is a complex and highly coordinated process orchestrated by temporal spatial activity of developmental pathways. How the different pathways interact to guide the developmental program remains an intriguing and open question. MAP3K1-JNK and Wnt are signaling pathways crucial for embryonic eyelid closure, an epithelial morphogenetic event conserved in mammals. Here we used a mouse model of eyelid development and genetic and biochemistry tools to investigate the relationships between the two pathways. We found that Wnt activation repressed MAP3K1 expression. Using Axin-LacZ reporter mice, spatial Wnt activity was detected in the leading edge of the developing eyelid. Conditional knockout of Wntless (Wls) in ocular surface ectoderm blocked eyelid formation, and significantly increased MAP3K1 expression in eyelid cells at the nasal canthus region. Conversely, knockout of Dkk2, encoding a canonical Wnt antagonist, resulted in an increase of Wnt activity in cells at the upper eyelid margin near the nasal canthus. Up-regulation of Wnt signaling in the Dkk2-knockout embryos corresponded to down-regulation of MAP3K1 expression. In vitro data showed that Wnt3a treatment decreased MAP3K1 promoter activity, whereas activation of Wnt by lithium chloride inhibited MAP3K1 expression, and attenuated MAP3K1-mediated JNK activity. Our data identify a unique signal crosstalk between Wnt signaling and the MAP3K1-JNK pathway in epithelial morphogenesis.

Stress-activated MAPKs and CRM1 regulate the subcellular localization of Net1A to control cell motility and invasion

The neuroepithelial cell transforming gene 1A (Net1A, an isoform of Net1) is a RhoA subfamily guanine nucleotide exchange factor (GEF) that localizes to the nucleus in the absence of stimulation, preventing it from activating RhoA. Once relocalized in the cytosol, Net1A stimulates cell motility and extracellular matrix invasion. In the present work, we investigated mechanisms responsible for the cytosolic relocalization of Net1A. We demonstrate that inhibition of MAPK pathways blocks Net1A relocalization, with cells being most sensitive to JNK pathway inhibition. Moreover, activation of the JNK or p38 MAPK family pathway is sufficient to elicit Net1A cytosolic localization. Net1A relocalization stimulated by EGF or JNK activation requires nuclear export mediated by CRM1. JNK1 (also known as MAPK8) phosphorylates Net1A on serine 52, and alanine substitution at this site prevents Net1A relocalization caused by EGF or JNK activation. Glutamic acid substitution at this site is sufficient for Net1A relocalization and results in elevated RhoA signaling to stimulate myosin light chain 2 (MLC2, also known as MYL2) phosphorylation and F-actin accumulation. Net1A S52E expression stimulates cell motility, enables Matrigel invasion and promotes invadopodia formation. These data highlight a novel mechanism for controlling the subcellular localization of Net1A to regulate RhoA activation, cell motility, and invasion.

"Positive Regulation of RNA Metabolic Process" Ontology Group Highly Regulated in Porcine Oocytes Matured In Vitro: A Microarray Approach

The cumulus-oocyte complexes (COCs) growth and development during folliculogenesis and oogenesis are accompanied by changes involving synthesis and accumulation of large amount of RNA and proteins. In this study, the transcriptomic profile of genes involved in “oocytes RNA synthesis” in relation to in vitro maturation in pigs was investigated for the first time. The RNA was isolated from oocytes before and after in vitro maturation (IVM). Interactions between differentially expressed genes/proteins belonging to “positive regulation of RNA metabolic process” ontology group were investigated by STRING10 software. Using microarray assays, we found expression of 12258 porcine transcripts. Genes with fold change higher than |2| and with corrected p value lower than 0.05 were considered as differentially expressed. The ontology group “positive regulation of RNA metabolic process” involved differential expression of AR, INHBA, WWTR1, FOS, MEF2C, VEGFA, IKZF2, IHH, RORA, MAP3K1, NFAT5, SMARCA1, EGR1, EGR2, MITF, SMAD4, APP, and NR5A1 transcripts. Since all of the presented genes were downregulated after IVM, we suggested that they might be significantly involved in regulation of RNA synthesis before reaching oocyte MII stage. Higher expression of “RNA metabolic process” related genes before IVM indicated that they might be recognized as important markers and specific “transcriptomic fingerprint” of RNA template accumulation and storage for further porcine embryos growth and development.

Dickkopf-4 is frequently overexpressed in epithelial ovarian carcinoma and promotes tumor invasion

Background

Dickkopf-4 (DKK4), a member of DKK family, appears to be a divergent protein. It remained multi-biological functions in carcinogenesis. The effect of DKK4 on the ovarian cancer cells remains unclear. This study detected the clinical significance of DKK4 in epithelial ovarian cancer (EOC) patients and its role in invasion.

Methods

QRT-PCR and western blot analysis were used to examine the levels of DKK4 mRNA and protein in 33 EOC tissues and 33 benign ovarian tumors. Immunohistochemical analysis was performed to assess DKK4 expression in 239 EOC samples. siRNA-mediated DKK4 silence was conducted. Transwell assay was used to detect the invasive ability. Phalloidin was used to stain the formations of actin filaments.

Results

The expressions of DKK4 mRNA and protein were elevated in EOC tissues as compared with those in benign ovarian tumors (p = 0.001 and <0.0001 respectively). Immunohistochemical results showed the strong expression of DKK4 protein was positively associated with late FIGO stage (p = 0.005) and poor disease free survival in univariate and multivariate analysis (p < 0.0001 and p = 0.001, respectively). SiRNA-mediated DKK4 knockdown inhibited cell invasive ability (all p < 0.0001) and the formations of actin filaments. DKK4 could promote the phosphration of c-JUN and JNK (p < 0.0001 and p = 0.001, respectively).

Conclusions

Our results indicated that DKK4 might be contributed to predicting EOC progression and prognosis. DKK4 could promote the invasion of EOC through JNK activation.

Slit-Robo Repulsive Signaling Extrudes Tumorigenic Cells from Epithelia

Cells dynamically interact throughout animal development to coordinate growth and deter disease. For example, cell-cell competition weeds out aberrant cells to enforce homeostasis. In Drosophila, tumorigenic cells mutant for the cell polarity gene scribble (scrib) are actively eliminated from epithelia when surrounded by wild-type cells. While scrib cell elimination depends critically on JNK signaling, JNK-dependent cell death cannot sufficiently explain scrib cell extirpation. Thus, how JNK executed cell elimination remained elusive. Here, we show that repulsive Slit-Robo2-Ena signaling exerts an extrusive force downstream of JNK to eliminate scrib cells from epithelia by disrupting E-cadherin. While loss of Slit-Robo2-Ena in scrib cells potentiates scrib tumor formation within the epithelium, Robo2-Ena hyperactivation surprisingly triggers luminal scrib tumor growth following excess extrusion. This extrusive signaling is amplified by a positive feedback loop between Slit-Robo2-Ena and JNK. Our observations provide a potential causal mechanism for Slit-Robo dysregulation in numerous human cancers.

Embryologic and Fetal Development of the Human Eyelid

Purpose:

To review the recent data about eyelid morphogenesis, and outline a timeline for eyelid development from the very early stages during embryonic life till final maturation of the eyelid late in fetal life.

Methods:

The authors extensively review major studies detailing human embryologic and fetal eyelid morphogenesis. These studies span almost a century and include some more recent cadaver studies. Numerous studies in the murine model have helped to better understand the molecular signals that govern eyelid embryogenesis. The authors summarize the current findings in molecular biology, and highlight the most significant studies in mice regarding the multiple and interacting signaling pathways involved in regulating normal eyelid morphogenesis.

Results:

Eyelid morphogenesis involves a succession of subtle yet strictly regulated morphogenetic episodes of tissue folding, proliferation, contraction, and even migration, which may occur simultaneously or in succession.

Conclusions:

Understanding the extraordinary process of building eyelid tissue in embryonic life, and deciphering its underlying signaling machinery has far reaching clinical implications beyond understanding the developmental abnormalities involving the eyelids, and may pave the way for achieving scar-reducing therapies in adult mammalian wounds, or control the spread of malignancies.

The authors describe in detail the recent advances in the knowledge of embryological and fetal development of the eyelids, and briefly outline the molecular basis of eyelid morphogenesis.

TGF-β Down-regulates Apolipoprotein M Expression through the TAK-1-JNK-c-Jun Pathway in HepG2 Cells

Apolipoprotein M (apoM) is a relatively novel apolipoprotein that plays pivotal roles in many dyslipidemia-associated diseases; however, its regulatory mechanisms are poorly understood. Many cytokines have been identified that down-regulate apoM expression in HepG2 cells, among which transforming growth factor-β (TGF-β) exerts the most potent effects. In addition, c-Jun, a member of the activated protein 1 (AP-1) family whose activity is modulated by c-Jun N-terminal kinase (JNK), decreases apoM expression at the transcriptional level by binding to the regulatory element in the proximal apoM promoter. In this study, we investigated the molecular mechanisms through which TGF-β decreases the apoM level in HepG2 cells. The results revealed that TGF-β inhibited apoM expression at both the mRNA and protein levels in a dose- and time-dependent manner and that it suppressed apoM secretion. These effects were attenuated by treatment of cells with either SP600125 (JNK inhibitor) or c-Jun siRNA. 5Z-7-oxozeaenol [(a TGF-β-activated kinase 1 (TAK-1) inhibitor)] also attenuated the TGF-β-mediated inhibition of apoM expression and suppressed the activation of JNK and c-Jun. These results have demonstrated that TGF-β suppresses apoM expression through the TAK-1-JNK-c-Jun pathway in HepG2 cells.

The core planar cell polarity gene, Vangl2, directs adult corneal epithelial cell alignment and migration

This study shows that the core planar cell polarity (PCP) genes direct the aligned cell migration in the adult corneal epithelium, a stratified squamous epithelium on the outer surface of the vertebrate eye. Expression of multiple core PCP genes was demonstrated in the adult corneal epithelium. PCP components were manipulated genetically and pharmacologically in human and mouse corneal epithelial cells in vivo and in vitro. Knockdown of VANGL2 reduced the directional component of migration of human corneal epithelial (HCE) cells without affecting speed. It was shown that signalling through PCP mediators, dishevelled, dishevelled-associated activator of morphogenesis and Rho-associated protein kinase directs the alignment of HCE cells by affecting cytoskeletal reorganization. Cells in which VANGL2 was disrupted tended to misalign on grooved surfaces and migrate across, rather than parallel to the grooves. Adult corneal epithelial cells in which Vangl2 had been conditionally deleted showed a reduced rate of wound-healing migration. Conditional deletion of Vangl2 in the mouse corneal epithelium ablated the normal highly stereotyped patterns of centripetal cell migration in vivo from the periphery (limbus) to the centre of the cornea. Corneal opacity owing to chronic wounding is a major cause of degenerative blindness across the world, and this study shows that Vangl2 activity is required for directional corneal epithelial migration.

JNK Signaling: Regulation and Functions Based on Complex Protein-Protein Partnerships

The c-Jun N-terminal kinases (JNKs), as members of the mitogen-activated protein kinase (MAPK) family, mediate eukaryotic cell responses to a wide range of abiotic and biotic stress insults. JNKs also regulate important physiological processes, including neuronal functions, immunological actions, and embryonic development, via their impact on gene expression, cytoskeletal protein dynamics, and cell death/survival pathways. Although the JNK pathway has been under study for >20 years, its complexity is still perplexing, with multiple protein partners of JNKs underlying the diversity of actions. Here we review the current knowledge of JNK structure and isoforms as well as the partnerships of JNKs with a range of intracellular proteins. Many of these proteins are direct substrates of the JNKs. We analyzed almost 100 of these target proteins in detail within a framework of their classification based on their regulation by JNKs. Examples of these JNK substrates include a diverse assortment of nuclear transcription factors (Jun, ATF2, Myc, Elk1), cytoplasmic proteins involved in cytoskeleton regulation (DCX, Tau, WDR62) or vesicular transport (JIP1, JIP3), cell membrane receptors (BMPR2), and mitochondrial proteins (Mcl1, Bim). In addition, because upstream signaling components impact JNK activity, we critically assessed the involvement of signaling scaffolds and the roles of feedback mechanisms in the JNK pathway. Despite a clarification of many regulatory events in JNK-dependent signaling during the past decade, many other structural and mechanistic insights are just beginning to be revealed. These advances open new opportunities to understand the role of JNK signaling in diverse physiological and pathophysiological states.

Wnt-11 overexpression promoting the invasion of cervical cancer cells

Wnt-11 is a positive regulator of the Wnt signaling pathway, which plays a crucial role in carcinogenesis. However, Wnt-11 expression in cervical cancer has not been well investigated. The aim of this study was to investigate the role of Wnt-11 in cervical tumor proliferation and invasion. This study examined 24 normal cervical squamous epithelia, 29 cervical intraepithelial neoplasia (CIN), and 78 cervical cancer samples. The expression of Wnt-11 was investigated by immunohistochemistry and quantitative reverse transcription-polymerase chain reaction analysis. The expression of the high-risk human papilloma virus (HR-HPV) E6 oncoprotein was also investigated by immunohistochemistry. In addition, the expression of Wnt-11, HR-HPV E6, JNK-1, phosphorylated JNK-1(P-JNK1), and β-catenin was examined by western blot analysis following Wnt-11 knockdown or overexpression in HeLa or SiHa cells, respectively. The promotion of cervical cancer cell proliferation and invasion was investigated using the cell counting kit-8 and Matrigel invasion assay, respectively. Wnt-11 and HR-HPV E6 expression increased in a manner that corresponded with the progression of cervical cancer and was significantly correlated with the International Federation of Gynecology and Obstetrics cancer stage, lymph node metastasis, tumor size, and HPV infection. Wnt-11 protein expression was positively associated with HR-HPV E6 protein expression in all 78 cervical cancer samples (P < 0.001). Furthermore, Wnt-11 was positively associated with P-JNK1 expression and promoted cervical cancer cell proliferation and invasion. These observations suggest that the increased Wnt-11 expression observed in cervical cancer cells may lead to the phosphorylation and activation of JNK-1 and significantly promote tumor cell proliferation and cell migration/invasion through activation of the Wnt/JNK pathway. Consequently, Wnt-11 may serve as a novel target for cervical cancer therapy.

Molecular biology and genetics of embryonic eyelid development

The embryology of the eyelid is a complex process that includes interactions between the surface ectoderm and mesenchymal tissues. In the mouse and human, the eyelids form and fuse before birth; they open prenatally in the human and postnatally in the mouse. In the mouse, cell migration is stimulated by different growth factors such as FGF10, TGF-α, Activin B, and HB-EGF. These growth factors modulate downstream BMP4 signaling, the ERK cascade, and JNK/c-JUN. Several mechanisms, such as the Wnt/β-catenin signaling pathway, may inhibit and regulate eyelid fusion. Eyelid opening, on the other hand, is driven by the BMP/Smad signaling system. Several human genetic disorders result from dysregulation of the above molecular pathways.

Ectodermal Wnt controls nasal pit morphogenesis through modulation of the BMP/FGF/JNK signaling axis

BACKGROUND

Mutations of WNT3, WNT5A, WNT9B, and WNT11 genes are associated with orofacial birth defects, including nonsyndromic cleft lip with cleft palate in humans. However, the source of Wnt ligands and their signaling effects on the orofacial morphogenetic process remain elusive.

RESULTS

Using Foxg1-Cre to impair Wnt secretion through the inactivation of Gpr177/mWls, we investigate the relevant regulation of Wnt production and signaling in nasal-facial development. Ectodermal ablation of Gpr177 leads to severe facial deformities resulting from dramatically reduced cell proliferation and increased cell death due to a combined loss of WNT, FGF and BMP signaling in the developing facial prominence. In the invaginating nasal pit, the Gpr177 disruption also causes a detrimental effect on migration of the olfactory epithelial cells into the mesenchymal region. The blockage of Wnt secretion apparently impairs the olfactory epithelial cells through modulation of JNK signaling.

CONCLUSIONS

Our study thus suggests the head ectoderm, including the facial ectoderm and the neuroectoderm, as the source of canonical as well as noncanonical Wnt ligands during early development of the nasal-facial prominence. Both β-catenin-dependent and -independent signaling pathways are required for proper development of these morphogenetic processes.

A novel link between FMR gene and the JNK pathway provides clues to possible role in malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive form of thoracic cancer with poor prognosis. While some studies have identified the molecular alterations associated with MPM, little is known about their role in MPM. For example, fragile X mental retardation (FMR) gene is up-regulated in MPM but its role in MPM is unknown. Here, utilizing Drosophila genetics, I investigate the possible role FMR may be playing in MPM. I provide evidence which suggests that FMR may contribute to tumorigenesis by up-regulating a matrix metalloprotease (MMP) and by degrading the basement membrane (BM), both important for tumor metastasis. I also demonstrate a novel link between FMR and the JNK pathway and suggest that the effects of FMR in MPM could in part be mediated by up-regulation of the JNK pathway.

Gene-Environment Interactions Target Mitogen-activated Protein 3 Kinase 1 (MAP3K1) Signaling in Eyelid Morphogenesis

Gene-environment interactions determine the biological outcomes through mechanisms that are poorly understood. Mouse embryonic eyelid closure is a well defined model to study the genetic control of developmental programs. Using this model, we investigated how exposure to dioxin-like environmental pollutants modifies the genetic risk of developmental abnormalities. Our studies reveal that mitogen-activated protein 3 kinase 1 (MAP3K1) signaling is a focal point of gene-environment cross-talk. Dioxin exposure, acting through the aryl hydrocarbon receptor (AHR), blocked eyelid closure in genetic mutants in which MAP3K1 signaling was attenuated but did not disturb this developmental program in either wild type or mutant mice with attenuated epidermal growth factor receptor or WNT signaling. Exposure also markedly inhibited c-Jun phosphorylation in Map3k1(+/-) embryonic eyelid epithelium, suggesting that dioxin-induced AHR pathways can synergize with gene mutations to inhibit MAP3K1 signaling. Our studies uncover a novel mechanism through which the dioxin-AHR axis interacts with the MAP3K1 signaling pathways during fetal development and provide strong empirical evidence that specific gene alterations can increase the risk of developmental abnormalities driven by environmental pollutant exposure.

Congenital upper eyelid coloboma: embryologic, nomenclatorial, nosologic, etiologic, pathogenetic, epidemiologic, clinical, and management perspectives

Purpose:

To review the recent literature and describe the authors’ experience with congenital upper eyelid coloboma.

Methods:

In this review, we will summarize the embryologic and etiopathogenetic bases of congenital upper eyelid coloboma, and study the published clinical reports. We will also attempt to briefly shed some light on the rarer syndromic curiosities associated with upper eyelid coloboma.

Results:

Congenital upper eyelid colobomas are one of the few nontraumatic oculoplastic emergencies that may occasionally present in the first few days of life with a corneal ulcer and may even present with impending perforation. They can present with or without corneopalpebral adhesions, may be isolated findings or a part of a larger spectrum of congenital anomalies as in the case of Fraser syndrome or Goldenhar syndrome, or could be associated with other rare curiosities that could challenge the clinician with a huge diagnostic dilemma.

Conclusions:

Existing literature dealing with congenital colobomas of the upper eyelid is fraught with nosologic problems, confusing etiologies, and overlapping clinical features. We attempted to clarify the salient clinical features, outline the management principles, and until a time in the not-so-distant future where advances in molecular genetic testing would help redefine the etiology and the diverse clinical spectrum of genetic diseases associated with upper eyelid colobomas, we propose a simplified classification scheme based on the relation of the coloboma to the cornea, the presence or absence of systemic features, and all the syndromic and nonsyndromic associations of congenital coloboma of the upper eyelid known today.

In this review, the authors will describe the pathogenesis of upper eyelid coloboma, suggest a new simplified classification system, describe the clinical picture in detail, clarify the various syndromic associations of upper eyelid coloboma, and lay out the basic surgical principles of management.

Voxel-based analysis of the immediate early gene, c-jun, in the honey bee brain after a sucrose stimulus

Immediate early genes (IEGs) have served as useful markers of brain neuronal activity in mammals, and more recently in insects. The mammalian canonical IEG, c-jun, is part of regulatory pathways conserved in insects and has been shown to be responsive to alarm pheromone in honey bees. We tested whether c-jun was responsive in honey bees to another behaviourally relevant stimulus, sucrose, in order to further identify the brain regions involved in sucrose processing. To identify responsive regions, we developed a new method of voxel-based analysis of c-jun mRNA expression. We found that c-jun is expressed in somata throughout the brain. It was rapidly induced in response to sucrose stimuli, and it responded in somata near the antennal and mechanosensory motor centre, mushroom body calices and lateral protocerebrum, which are known to be involved in sucrose processing. c-jun also responded to sucrose in somata near the lateral suboesophageal ganglion, dorsal optic lobe, ventral optic lobe and dorsal posterior protocerebrum, which had not been previously identified by other methods. These results demonstrate the utility of voxel-based analysis of mRNA expression in the insect brain.

Regulation of a serine protease homolog by the JNK pathway during thoracic development of Drosophila melanogaster

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Scarface is up-regulated in peripodial epithelium and peripodial stalk cells in wing disc.

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Overexpression of JNK pathway causes up-regulation of scarface.

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Down regulation of JNK pathway results in down regulation of scarface.

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Scarface knockdown in wing disc phenocopies JNK pathway defect.

The importance of the Jun N-terminal Kinase (JNK) pathway during normal development and tumor invasion has been well documented in Drosophila. Here, this pathway plays important roles in epithelial morphogenesis, wound healing, apoptosis, immunity and regulation of lifespan. However, which downstream molecules facilitate these effects is not very well elucidated. In this study, data are presented on a serine protease homolog (SPH), scarface. These data show that scarface is under regulatory control of the JNK pathway and that this pathway is both necessary and sufficient for its expression within the context of thoracic development. Consequently, down-regulation of scarface results in a thoracic-cleft phenotype that phenocopies the JNK pathway defect. A possible role of scarface during thoracic development in Drosophila is discussed.

A RING to rule them all? Insights into the Map3k1 PHD motif provide a new mechanistic understanding into the diverse roles of Map3k1

Despite the sizable number of components that comprise Mapk cascades, Map3k1 is the only element that contains both a kinase domain and a plant homeodomain (PHD) motif, allowing Map3k1 to regulate the protein phosphorylation and ubiquitin proteasome systems. As such, Map3k1 has complex roles in the regulation of cell death, survival, migration and differentiation. Numerous mouse and human genetic analyses have demonstrated that Map3k1 is of critical importance for the immune system, cardiac tissue, testis, wound healing, tumorigenesis and cancer. Recent gene knockin of Map3k1 to mutate the E2 binding site within the Map3k1 PHD motif and high throughput ubiquitin protein array screening for Map3k1 PHD motif substrates provide critical novel insights into Map3k1 PHD motif signal transduction and bring a brand-new understanding to Map3k1 signaling in mammalian biology.

The MEKK1 PHD ubiquitinates TAB1 to activate MAPKs in response to cytokines

Unlike the other MAP3Ks, MEKK1 (encoded by Map3k1) contains a PHD motif. To understand the role of this motif, we have created a knockin mutant of mouse Map3k1 (Map3k1^mPHD) with an inactive PHD motif. Map3k1^mPHD ES cells demonstrate that the MEKK1 PHD controls p38 and JNK activation during TGF-β, EGF and microtubule disruption signalling, but does not affect MAPK responses to hyperosmotic stress. Protein microarray profiling identified the adaptor TAB1 as a PHD substrate, and TGF-β- or EGF-stimulated Map3k1^mPHD ES cells exhibit defective non-canonical ubiquitination of MEKK1 and TAB1. The MEKK1 PHD binds and mediates the transfer of Lys63-linked poly-Ub, using the conjugating enzyme UBE2N, onto TAB1 to regulate TAK1 and MAPK activation by TGF-β and EGF. Both the MEKK1 PHD and TAB1 are critical for ES-cell differentiation and tumourigenesis. Map3k1^mPHD/+ mice exhibit aberrant cardiac tissue, B-cell development, testis and T-cell signalling.

Antioxidants maintain E-cadherin levels to limit Drosophila prohemocyte differentiation

Mitochondrial reactive oxygen species (ROS) regulate a variety of biological processes by networking with signal transduction pathways to maintain homeostasis and support adaptation to stress. In this capacity, ROS have been shown to promote the differentiation of progenitor cells, including mammalian embryonic and hematopoietic stem cells and Drosophila hematopoietic progenitors (prohemocytes). However, many questions remain about how ROS alter the regulatory machinery to promote progenitor differentiation. Here, we provide evidence for the hypothesis that ROS reduce E-cadherin levels to promote Drosophila prohemocyte differentiation. Specifically, we show that knockdown of the antioxidants, Superoxide dismutatase 2 and Catalase reduce E-cadherin protein levels prior to the loss of Odd-skipped-expressing prohemocytes. Additionally, over-expression of E-cadherin limits prohemocyte differentiation resulting from paraquat-induced oxidative stress. Furthermore, two established targets of ROS, Enhancer of Polycomb and FOS, control the level of E-cadherin protein expression. Finally, we show that knockdown of either Superoxide dismutatase 2 or Catalase leads to an increase in the E-cadherin repressor, Serpent. As a result, antioxidants and targets of ROS can control E-cadherin protein levels, and over-expression of E-cadherin can ameliorate the prohemocyte response to oxidative stress. Collectively, these data strongly suggest that ROS promote differentiation by reducing E-cadherin levels. In mammalian systems, ROS promote embryonic stem cell differentiation, whereas E-cadherin blocks differentiation. However, it is not known if elevated ROS reduce E-cadherin to promote embryonic stem cell differentiation. Thus, our findings may have identified an important mechanism by which ROS promote stem/progenitor cell differentiation.

Hair curvature: a natural dialectic and review

Although hair forms (straight, curly, wavy, etc.) are present in apparently infinite variations, each fibre can be reduced to a finite sequence of tandem segments of just three types: straight, bent/curly, or twisted. Hair forms can thus be regarded as resulting from genetic pathways that induce, reverse or modulate these basic curvature modes. However, physical interconversions between twists and curls demonstrate that strict one-to-one correspondences between them and their genetic causes do not exist. Current hair-curvature theories do not distinguish between bending and twisting mechanisms. We here introduce a multiple papillary centres (MPC) model which is particularly suitable to explain twisting. The model combines previously known features of hair cross-sectional morphology with partially/completely separated dermal papillae within single follicles, and requires such papillae to induce differential growth rates of hair cortical material in their immediate neighbourhoods. The MPC model can further help to explain other, poorly understood, aspects of hair growth and morphology. Separate bending and twisting mechanisms would be preferentially affected at the major or minor ellipsoidal sides of fibres, respectively, and together they exhaust the possibilities for influencing hair-form phenotypes. As such they suggest dialectic for hair-curvature development. We define a natural-dialectic (ND) which could take advantage of speculative aspects of dialectic, but would verify its input data and results by experimental methods. We use this as a top-down approach to first define routes by which hair bending or twisting may be brought about and then review evidence in support of such routes. In particular we consider the wingless (Wnt) and mammalian target of rapamycin (mTOR) pathways as paradigm pathways for molecular hair bending and twisting mechanisms, respectively. In addition to the Wnt canonical pathway, the Wnt/Ca(2+) and planar cell polarity (PCP) pathways, and others, can explain many alternatives and specific variations of hair bending phenotypes. Mechanisms for hair papilla budding or its division by bisection or fission can explain MPC formation. Epithelial-to-mesenchymal (EMT) and mesenchymal-to-epithelial (MET) transitions, acting in collaboration with epithelial-mesenchymal communications are also considered as mechanisms affecting hair growth and its bending and twisting. These may be treated as sub-mechanisms of an overall development from neural-crest stem cell (NCSC) lineages to differentiated hair follicle (HF) cell types, thus providing a unified framework for hair growth and development.

Leader cell positioning drives wound-directed collective migration in TGFβ-stimulated epithelial sheets

Motility analysis of collectively migrating epithelial sheets reveals the interplay between cellular density and leader cell positioning throughout a collective group, as well as the functional role of leader cell constraint in directing a migrating group of cells.

During wound healing and cancer metastasis, cells are frequently observed to migrate in collective groups. This mode of migration relies on the cooperative guidance of leader and follower cells throughout the collective group. The upstream determinants and molecular mechanisms behind such cellular guidance remain poorly understood. We use live-cell imaging to track the behavior of epithelial sheets of keratinocytes in response to transforming growth factor β (TGFβ), which stimulates collective migration primarily through extracellular regulated kinase 1/2 (Erk1/2) activation. TGFβ-treated sheets display a spatial pattern of Erk1/2 activation in which the highest levels of Erk1/2 activity are concentrated toward the leading edge of a sheet. We show that Erk1/2 activity is modulated by cellular density and that this functional relationship drives the formation of patterns of Erk1/2 activity throughout sheets. In addition, we determine that a spatially constrained pattern of Erk1/2 activity results in collective migration that is primarily wound directed. Conversely, global elevation of Erk1/2 throughout sheets leads to stochastically directed collective migration throughout sheets. Our study highlights how the spatial patterning of leader cells (cells with elevated Erk1/2 activity) can influence the guidance of a collective group of cells during wound healing.

The development of a novel high throughput computational tool for studying individual and collective cellular migration

Understanding how cells migrate individually and collectively during development and cancer metastasis can be significantly aided by a computation tool to accurately measure not only cellular migration speed, but also migration direction and changes in migration direction in a temporal and spatial manner. We have developed such a tool for cell migration researchers, named Pathfinder, which is capable of simultaneously measuring the migration speed, migration direction, and changes in migration directions of thousands of cells both instantaneously and over long periods of time from fluorescence microscopy data. Additionally, we demonstrate how the Pathfinder software can be used to quantify collective cell migration. The novel capability of the Pathfinder software to measure the changes in migration direction of large populations of cells in a spatiotemporal manner will aid cellular migration research by providing a robust method for determining the mechanisms of cellular guidance during individual and collective cell migration.

JNK is a novel regulator of intercellular adhesion

c-Jun N-terminal Kinase (JNK) is a family of protein kinases, which are activated by stress stimuli such as inflammation, heat stress and osmotic stress, and regulate diverse cellular processes including proliferation, survival and apoptosis. In this review, we focus on a recently discovered function of JNK as a regulator of intercellular adhesion. We summarize the existing knowledge regarding the role of JNK during the formation of cell-cell junctions. The potential mechanisms and implications for processes requiring dynamic formation and dissolution of cell-cell junctions including wound healing, migration, cancer metastasis and stem cell differentiation are also discussed.

Tumor necrosis factor-α promotes bile ductular transdifferentiation of mature rat hepatocytes in vitro

We previously showed that mature hepatocytes could transdifferentiate into bile ductular cells when placed in a collagen-rich microenvironment. To explore the mechanism of transdifferentiation, we examined whether inflammatory cytokines affected the phenotype of hepatocytes in a three-dimensional culture system. Spheroidal aggregates of rat hepatocytes were embedded within a type I collagen gel matrix and cultured in the presence of various cytokines. In the control, hepatocytes gradually lost expression of albumin, tyrosine aminotransferase, and hepatocyte nuclear factor (HNF)-4α, while aberrantly expressed bile ductular markers, including cytokeratin 19 (CK 19) and spermatogenic immunoglobulin superfamily (SgIGSF). Among the cytokines examined, tumor necrosis factor (TNF)-α inhibited expression of albumin and HNF-4α, both at mRNA and protein levels. After culturing for 2 weeks with TNF-α, hepatocytic spheroids were transformed into extensively branching tubular structures composed of CK 19- and SgIGSF-positive small cuboidal cells. These cells responded to secretin with an increase in secretion and expressed functional bile duct markers. TNF-α also induced the phosphorylation of Jun N-terminal kinase (JNK) and c-Jun, and the morphogenesis was inhibited by SP600125, a specific JNK inhibitor. Furthermore, in chronic rat liver injury induced by CCl(4) , ductular reaction in the centrilobular area demonstrated strong nuclear staining of phosphorylated c-Jun. Our results demonstrate that TNF-α promotes the ductular transdifferentiation of hepatocytes and suggest a role of TNF-α in the pathogenesis of ductular reaction.

Mummy, A UDP-N-acetylglucosamine pyrophosphorylase, modulates DPP signaling in the embryonic epidermis of Drosophila

The evolutionarily conserved JNK/AP-1 (Jun N-terminal kinase/activator protein 1) and BMP (Bone Morphogenetic Protein) signaling cascades are deployed hierarchically to regulate dorsal closure in the fruit fly Drosophila melanogaster. In this developmental context, the JNK/AP-1 signaling cascade transcriptionally activates BMP signaling in leading edge epidermal cells. Here we show that the mummy (mmy) gene product, which is required for dorsal closure, functions as a BMP signaling antagonist. Genetic and biochemical tests of Mmy's role as a BMP-antagonist indicate that its function is independent of AP-1, the transcriptional trigger of BMP signal transduction in leading edge cells. pMAD (phosphorylated Mothers Against Dpp) activity data show the mmy gene product to be a new type of epidermal BMP regulator - one which transforms a BMP ligand from a long- to a short-range signal. mmy codes for the single UDP-N-acetylglucosamine pyrophosphorylase in Drosophila, and its requirement for attenuating epidermal BMP signaling during dorsal closure points to a new role for glycosylation in defining a highly restricted BMP activity field in the fly. These findings add a new dimension to our understanding of mechanisms modulating the BMP signaling gradient.

Jun N-terminal kinase maintains tissue integrity during cell rearrangement in the gut

Tissue elongation is a fundamental morphogenetic process that generates the proper anatomical topology of the body plan and vital organs. In many elongating embryonic structures, tissue lengthening is driven by Rho family GTPase-mediated cell rearrangement. During this dynamic process, the mechanisms that modulate intercellular adhesion to allow individual cells to change position without compromising structural integrity are not well understood. In vertebrates, Jun N-terminal kinase (JNK) is also required for tissue elongation, but the precise cellular role of JNK in this context has remained elusive. Here, we show that JNK activity is indispensable for the rearrangement of endoderm cells that underlies the elongation of the Xenopus gut tube. Whereas Rho kinase is necessary to induce cell intercalation and remodel adhesive contacts, we have found that JNK is required to maintain cell-cell adhesion and establish parallel microtubule arrays; without JNK activity, the reorganizing endoderm dissociates. Depleting polymerized microtubules phenocopies this effect of JNK inhibition on endoderm morphogenesis, consistent with a model in which JNK regulates microtubule architecture to preserve adhesive contacts between rearranging gut cells. Thus, in contrast to Rho kinase, which generates actomyosin-based tension and cell movement, JNK signaling is required to establish microtubule stability and maintain tissue cohesion; both factors are required to achieve proper cell rearrangement and gut extension. This model of gut elongation has implications not only for the etiology of digestive tract defects, but sheds new light on the means by which intra- and intercellular forces are balanced to promote topological change, while preserving structural integrity, in numerous morphogenetic contexts.

The actin cross-linker Filamin/Cheerio mediates tumor malignancy downstream of JNK signaling

Cell shape dynamics, motility, and cell proliferation all depend on the actin cytoskeleton. Malignant cancer cells hijack the actin network to grow and migrate to secondary sites. Understanding the function of actin regulators is therefore of major interest. In the present study, we identify the actin cross-linking protein Filamin/Cheerio (Cher) as a mediator of malignancy in genetically defined Drosophila tumors. We show that in invasive tumors, resulting from cooperation of activated Ras with disrupted epithelial cell polarity, Cher is upregulated in a Jun N-terminal kinase (JNK)-dependent manner. Although dispensable in normal epithelium, Cher becomes required in the tumor cells for their growth and invasiveness. When deprived of Cher, these tumor clones lose their full potential to proliferate and breach tissue boundaries. Instead, the Cher-deficient clones remain confined within the limits of their source epithelium, permitting survival of the host animal. Through interaction with the myosin II heavy chain subunit, Cher is likely to strengthen the cortical actomyosin network and reinforce mechanical tension within the invasive tumors. Accordingly, Cher is required for aberrant expression of genes downstream of the Hippo/Yorkie signaling in the tumor tissue. Our study identifies Cher as a new target of JNK signaling that links cytoskeleton dynamics to tumor progression.

JNK pathway activation is controlled by Tao/TAOK3 to modulate ethanol sensitivity

Neuronal signal transduction by the JNK MAP kinase pathway is altered by a broad array of stimuli including exposure to the widely abused drug ethanol, but the behavioral relevance and the regulation of JNK signaling is unclear. Here we demonstrate that JNK signaling functions downstream of the Sterile20 kinase family gene tao/Taok3 to regulate the behavioral effects of acute ethanol exposure in both the fruit fly Drosophila and mice. In flies tao is required in neurons to promote sensitivity to the locomotor stimulant effects of acute ethanol exposure and to establish specific brain structures. Reduced expression of key JNK pathway genes substantially rescued the structural and behavioral phenotypes of tao mutants. Decreasing and increasing JNK pathway activity resulted in increased and decreased sensitivity to the locomotor stimulant properties of acute ethanol exposure, respectively. Further, JNK expression in a limited pattern of neurons that included brain regions implicated in ethanol responses was sufficient to restore normal behavior. Mice heterozygous for a disrupted allele of the homologous Taok3 gene (Taok3Gt) were resistant to the acute sedative effects of ethanol. JNK activity was constitutively increased in brains of Taok3Gt/+ mice, and acute induction of phospho-JNK in brain tissue by ethanol was occluded in Taok3Gt/+ mice. Finally, acute administration of a JNK inhibitor conferred resistance to the sedative effects of ethanol in wild-type but not Taok3Gt/+ mice. Taken together, these data support a role of a TAO/TAOK3-JNK neuronal signaling pathway in regulating sensitivity to acute ethanol exposure in flies and in mice.