Ginsenoside Rb1 attenuates lipopolysaccharide-induced chronic neuroinflammation in mice by tuning glial cell polarization

Objective:To evaluate whether ginsenoside Rb1(Rb1) can attenuate lipopolysaccharide(LPS)-induced chronic neuroinflammation in mice and to explore its relationship with glial cell polarization.Methods:Intraperitoneal injection with an escalating dose of LPS was used to establish a chronic neuroinflammation model in mice.Once LPS was initiated,10 or 20 mg/kg Rbl,or sterile saline,was administered for 14 consecutive days.Open field test and beam walking test were used to monitor the changes in behavior.The concentration of cytokines in the serum and brain were used to monitor the systemic inflammation and neuroinflammation,respectively.Molecules specific to each glial cell phenotype were used to investigate glial cell polarization.Results:Mice in the LPS group had reduced spontaneous activities and impaired beam walking performance.Rbl obviously eased LPS-induced behavior distu rbances.Regarding the levels of serum cytokines,both tumor necrosis factor-α(TNF-α) and interleukin-1β(IL-1β) were significantly increased,while interleukin-10(IL-10) and transforming growth factor β(TGF-β) remarkably decreased after LPS treatment(all P <.001).Rb1 treatment significantly attenuated LPS-induced serum cytokine changes(all P <.05).The results of quantitative polymerase chain reaction and western blotting showed that the mRNA and protein expression levels of TNF-α and complement component 3(C3) in the brain were significantly increased after LPS treatment(all P<.01).Rbl treatment significantly inhibited LPS-induced inflammation in the brain(all P <.05).Glial cell polarization analysis showed that M1 and M2 microglia,and A1 astrocytes increased following LPS treatment,while A2 astrocytes decreased.Rb1 treatment reduced M1 and M2 microglia,and A1 astrocytes,and significantly increased A2 astrocytes.Conclusion:Rb1 can attenuate chronic neuroinflammation induced by LPS in mice,which may be partially attributable to its fine tuning of microglia and astrocyte polarization.Rb1 has potential value for treating neurodegenerative diseases.

IL-6 prevents Th2 cell polarization by promoting SOCS3-dependent suppression of IL-2 signaling

Defective interleukin-6 (IL-6) signaling has been associated with Th2 bias and elevated IgE levels. However, the underlying mechanism by which IL-6 prevents the development of Th2-driven diseases remains unknown. Using a model of house dust mite (HDM)-induced Th2 cell differentiation and allergic airway inflammation, we showed that IL-6 signaling in allergen-specific T cells was required to prevent Th2 cell differentiation and the subsequent IgE response and allergic inflammation. Th2 cell lineage commitment required strong sustained IL-2 signaling. We found that IL-6 turned off IL-2 signaling during early T-cell activation and thus inhibited Th2 priming. Mechanistically, IL-6-driven inhibition of IL-2 signaling in responding T cells was mediated by upregulation of Suppressor Of Cytokine Signaling 3 (SOCS3). This mechanism could be mimicked by pharmacological Janus Kinase-1 (JAK1) inhibition. Collectively, our results identify an unrecognized mechanism that prevents the development of unwanted Th2 cell responses and associated diseases and outline potential preventive interventions.

Macrophage polarization in nerve injury： do Schwann cells play a role？

In response to peripheral nerve injury, the inflammatory response is almost entirely comprised of infiltrating macrophages. Macrophages are a highly plastic, heterogenic immune cell, playing an indispensable role in peripheral nerve injury, clearing debris and regulating the microenvironment to allow for efficient regeneration. There are several cells within the microenvironment that likely interact with macrophages to support their function – most notably the Schwann cell, the glial cell of the peripheral nervous system. Schwann cells express several ligands that are known to interact with receptors expressed by macrophages, yet the effects of Schwann cells in regulating macrophage phenotype remains largely unexplored. This review discusses macrophages in peripheral nerve injury and how Schwann cells may regulate their behavior.

The role of Rho GTPase family in cochlear hair cells and hearing

Rho GTPases are essential regulators of the actin cytoskeleton.They are involved in various physiological and biochemical processes such as the regulation of cytoskeleton dynamics,development,proliferation,survival,and regeneration.During the development of cochlear hair cells,Rho GTPases are activated by various extracellular signals through membrane receptors to further stimulate multiple downstream effectors.Specifically,RhoA,Cdc42,and Rac1,members of the classical subfamily of the Rho GTPase family,regulate the development and maintenance of cilia by inducing the polymerization of actin monomers and stabilizing actin filaments.In addition,they also regulate the normal morphology orientation of ciliary bundles in auditory hair cells,which is an important element of cell polarity regulation.Moreover,the actin-related pathways mediated by RhoA,Cdc42,and Rac1 also play a role in the motility of outer hair cells,indicating that the function of Rho GTPases is crucial in the highly polar auditory sensory system.In this review,we focus on the expression of RhoA,Cdc42,and Rac1 in cochlear hair cells and how these small molecules participate in ciliary bundle morphogenesis and cochlear hair cell movement.We also discuss the progress of current research investigating the use of these small molecules as drug targets for deafness treatment.

Mutual regulation of microglia and astrocytes after Gas6 inhibits spinal cord injury

Invasive inflammation and excessive scar formation are the main reasons for the difficulty in repairing nervous tissue after spinal cord injury.Microglia and astrocytes play key roles in the spinal cord injury micro-environment and share a close interaction.However,the mechanisms involved remain unclear.In this study,we found that after spinal cord injury,resting microglia(M0)were polarized into pro-inflammatory phenotypes(MG1 and MG3),while resting astrocytes were polarized into reactive and scar-forming phenotypes.The expression of growth arrest-specific 6(Gas6)and its receptor Axl were significantly down-regulated in microglia and astrocytes after spinal cord injury.In vitro experiments showed that Gas6 had negative effects on the polarization of reactive astrocytes and pro-inflammatory microglia,and even inhibited the cross-regulation between them.We further demonstrated that Gas6 can inhibit the polarization of reactive astrocytes by suppressing the activation of the Yes-associated protein signaling pathway.This,in turn,inhibited the polarization of pro-inflammatory microglia by suppressing the activation of the nuclear factor-κB/p65 and Janus kinase/signal transducer and activator of transcription signaling pathways.In vivo experiments showed that Gas6 inhibited the polarization of pro-inflammatory microglia and reactive astrocytes in the injured spinal cord,thereby promoting tissue repair and motor function recovery.Overall,Gas6 may play a role in the treatment of spinal cord injury.It can inhibit the inflammatory pathway of microglia and polarization of astrocytes,attenuate the interaction between microglia and astrocytes in the inflammatory microenvironment,and thereby alleviate local inflammation and reduce scar formation in the spinal cord.

Guided cell migration on a graded micropillar substrate

Cell migration is facilitated by the interaction of living cells and their local microenvironment.The local topography is one of the key factors regulating cell migration.Interaction between the surface topography and the cell behaviors is critical to understanding tissue development and regeneration.In this study,a dynamic mask photolithography technique has been utilized to fabricate a surface with graded micropillars.It has been demonstrated that the cells have been successfully guided to migrate from the sparse zone to the dense zone.The cell polarization angle has been characterized in both sparse zone and the dense zone.Compared to the dense zone,the cells in the sparse zone are more aligned along the direction of the micropillar spacing gradient,which enables the guided cell migration.Moreover,the effects of the micropillar spacing gradient,micropillar diameter,and micropillar height have been investigated in terms of the cell migration speed and cell spreading area.Finally,two issues significantly affecting the cell migration have been discussed:trapped cells between the micropillars and cell clusters.

A Traceable Cancer Model: DNA Damage, Fragile Site-SMGs, Mitotic Slippage, 4n-Genome-Reduction to Fitness-Gained, Initiating, 2n First Cells

We have known since 1976 that cancer evolves clonally from one initiated normal human cell, the first cell. Today we see that this fact has been overshadowed from federal funding choice of the mutation theory (MT), which not yet has shown tumorigenesis-initiation in normal human cells. Our suggested, death signaled, stress model from time delayed S-period (replication slowness), causing repair instability from under-replicated lesions in repetitive DNAs, herein has the objective of revealing, significant literature support from a mini-review. We reasoned that early versus late S-period stress would have different outcomes: early the slowness affecting mitotic slippage with diploid re-replication to 4n cells whereas late-S, with milder stress effect, producing diploid cells. In cancer burden, near-half is diploid, but tetraploid solid tumors have the attention. The initial 4n cells were special with orderly genomic reductive division to diploid first cells with measurable fitness-gain from hours-reduced total cell cycle time. Experimental data from Coxsakie-B3 virus infected normal fibroblasts, reiterated 4n cell production from death-signaled recovery-cells with progressive cell-phenotypic changes to polygonal and roundness cell-shapes, indistinguishable from diagnostic/prognostic cancer morphology. The 4n cells showed a self-inflicted 90° turn of the 4n nucleus before division, affecting a perpendicular orientation of the fitness-gained first cells relative to neighboring cells. In an illustrated cell cycle drawing with early and late S-period stress, it became clear that coding genes on borders of repair unstable satellite, repetitive DNA regions, could become mutated. We found these mutations to be tumor SMGs (significantly mutated genes). Evidential material was presented for loss of function genetics driving tumorigenesis to a parasitic lifestyle.

PI3K/SHIP2/PTEN pathway in cell polarity and hepatitis C virus pathogenesis

Hepatitis C virus(HCV) infects hepatocytes, polarized cells in the liver. Chronic HCV infection often leads to steatosis, fibrosis, cirrhosis and hepatocellular carcinoma, and it has been identified as the leading cause of liver transplantation worldwide. The HCV replication cycle is dependent on lipid metabolism and particularly an accumulation of lipid droplets in host cells. Phosphoinositides(PIs) are minor phospholipids enriched in different membranes and their levels are tightly regulated by specific PI kinases and phosphatases. PIs are implicated in a vast array of cellular responses that are central to morphogenesis, such as cytoskeletal changes, cytokinesis and the recruitment of downstream effectors to govern mechanisms involved in polarization and lumen formation. Important reviews of the literature identified phosphatidylinositol(Ptd Ins) 4-kinases, and their lipid products Ptd Ins(4)P, as critical regulators of the HCV life cycle. SH2-containing inositol polyphosphate 5-phosphatase(SHIP2), phosphoinositide 3-kinase(PI3K) and their lipid products Ptd Ins(3,4)P2 and Ptd Ins(3,4,5)P3, respectively, play an important role in the cell membrane and are key to the establishment of apicobasal polarity and lumen formation. In this review, we will focus on these new functions of PI3 K and SHIP2, and their deregulation by HCV, causing a disruption of apicobasal polarity, actin organization and extracellular matrix assembly. Finally we will highlight the involvement of this pathway in the event of insulin resistance and nonalcoholic fatty liver disease related to HCV infection.

Novel heat shock protein Hsp70L1 activates dendritic cells and acts as a Th1 polarizing adjuvant

Heat shock proteins (HSPs) are reported to act as effective adjuvants to elicit anti-tumor and anti-infection immunity. Here, we report that Hsp70-like protein 1 (Hsp70L1), a novel HSP derived from human dendritic cells (DCs), has potent adjuvant effects that polarize responses toward Th1. With a calculated molecular weight of 54.8 kDa, Hsp70L1 is smaller in size than Hsp70 but resembles it both structurally and functionally. Hsp70L1 shares common receptors on DCs with Hsp70 and can interact with DCs, promoting DC maturation and stimulating secretion of the proinflammatory cytokines interleukin 12p70 (IL-12p70), IL-1beta, tumor necrosis factor-alpha (TNF-alpha), and the chemokines IP-10, macrophage inflammatory protein-1alpha (MIP-1alpha), MIP-1beta, and normal T cell expressed and secreted (RANTES). The induction of interferon-gamma-inducible protein 10 (IP-10) secretion by Hsp70L1 is not shared by Hsp70, and other functional differences include more potent stimulation of DC IL-12p70, CC-chemokine, and CCR7 and CXCR4 expression by Hsp70L1. Immunization of mice with the hybrid peptide Hsp70L1-ovalbumin(OVA)(257-264) induces an OVA(257-264)-specific Th1 response and cytotoxic T lymphocyte (CTL) that results in significant inhibition of E.G7-OVA tumor growth. The ability of Hsp70L1 to activate DCs indicates its potential as a novel adjuvant for use with peptide immunizations; the Hsp70L1 antigen peptide hybrid may serve as a more effective vaccine for the control of cancer and infectious diseases.

The Role of the Southern Hemisphere Polar Cell on Antarctic Sea Ice Variability

The study explores modes of variability in the Southern Polar Cell and their relationship with known global climate modes and Antarctic sea ice. It is found that Polar Cell is barotropic in nature and 500 hPa geo-potential height (Z500) field can satisfactorily represent variability in the Polar Cell. First, three leading Empirical Orthogonal Function (EOF) modes of Z500 account for nearly 80% of observed variability in the Polar Cell. Dominant mode (PC1500) comprises of high pressure divergence zone over Antarctica. Second leading mode (PC2500) is low pressure zone covering Amundsen-Bellingshausen Sea (ABS) similar to ABS low feature. A new climate mode called Polar Coastal Index (PCI) is defined, which describes more than 15% and close to 30% variability of circumpolar trough and ABS low, respectively. Out of four modes defined in this study, only PCI and PC2500 show linear trends and clear seasonality. Interestingly, both modes are affected by modulation of ABS low due to tropical ENSO forcing. SAM signature is present in Polar Cell as PC1500 shares large variance with it. The largest impact on sea ice comes from PC2500 followed by PC1500 in the Antarctic Dipole regions. However, this study suggests contemporary sea ice trends cannot be sustained, and can reverse given that trends in PCI and PC2500 favour a reversal. These results indicate that ENSO-driven Polar Cell variability plays a crucial role influencing Antarctic sea ice as it interacts with other climate modes and leads the combined impact at the interannual time scale.

Prostate tumor neuroendocrine differentiation via EMT: The road less traveled

The long-standing challenge in the treatment of prostate cancer is to overcome therapeutic resistance during progression to lethal disease.Aberrant transforming-growth factor-b(TGF-b)signaling accelerates prostate tumor progression in a transgenic mouse model via effects on epithelial-mesenchymal transition(EMT),and neuroendocrine differentiation driving tumor progression to castration-resistant prostate cancer(CRPC).Neuroendocrine prostate cancer(NEPC)is highly aggressive exhibiting reactivation of developmental programs associated with EMT induction and stem cell-like characteristics.The androgen receptor(AR)is a critical driver of tumor progression as well as therapeutic response in patients with metastatic CRPC.The signaling interactions between the TGF-β mechanistic network and AR axis impact the EMT phenotypic conversions,and perturbation of epithelial homeostasis via EMT renders a critical venue for epithelial derived tumors to become invasive,acquire the neuroendocrine phenotype,and rapidly metastasize.Combinations of microtubule targeting taxane chemotherapy and androgen/AR targeting therapies have survival benefits in CRPC patients,but therapeutic resistance invariability develops,leading to mortality.Compelling evidence from our group recently demonstrated that chemotherapy(cabazitaxel,second line taxane chemotherapy),or TGF-β receptor signaling targeted therapy,caused reversion of EMT to mesenchymal-epithelial transition and tumor re-differentiation,in in vitro and in vivo prostate cancer models.In this review,we discuss the functional contribution of EMT dynamic changes to the development of the neuroendocrine phenotypedthe newly characterized pathological feature of prostate tumors in the context of the tumor microenvironment-navigated cell lineage changes and the role of this neuroendocrine phenotype in metastatic progression and therapeutic resistance.

Genome‑wide characterization of the Rho family in cotton provides insights into fiber development

Background:Cotton is the source of natural fibers globally,fulfilling 90%of the textile industry’s requirements.However,fiber development is a complex biological process comprising four stages.Fiber develops from a single cell,and cell elongation is a vital process in fiber development.Therefore,it is pertinent to understand and exploit mechanisms underlying cell elongation during fiber development.A previous report about cell division control protein 42(CDC-42)with its key role in cell elongation in eukaryotes inspired us to explore its homologs Rho GTPases for understanding of cell elongation during cotton fiber development.Result:We classified 2066 Rho proteins from 8 Gossypium species into 5 and 8 groups within A and D sub-genomes,respectively.Asymmetric evolution of Rho members was observed among five tetraploids.Population fixation statistics between two short and long fiber genotypes identified highly diverged regions encompassing 34 Rho genes in G.hirustum,and 31 of them were retained through further validation by genome wide association analysis(GWAS).Moreover,a weighted gene co-expression network characterized genome-wide expression patteren of Rho genes based on previously published transcriptome data.Twenty Rho genes from five modules were identified as hub genes which were potentially related to fiber development.Interaction networks of 5 Rho genes based on transcriptional abundance and gene ontology(GO)enrichment emphasized the involvement of Rho in cell wall biosynthesis,fatty acid elongation,and other biological processes.Conclusion:Our study characterized the Rho proteins in cotton,provided insights into the cell elongation of cotton fiber and potential application in cotton fiber improvement.

Omics Views of Mechanisms for Cell Fate Determination in Early Mammalian Development

During mammalian preimplantation development,a totipotent zygote undergoes several cell cleavages and two rounds of cell fate determination,ultimately forming a mature blastocyst.Along with compaction,the establishment of apicobasal cell polarity breaks the symmetry of an embryo and guides subsequent cell fate choice.Although the lineage segregation of the inner cell mass(ICM)and trophectoderm(TE)is the first symbol of cell differentiation,several molecules have been shown to bias the early cell fate through their inter-cellular variations at much earlier stages,including the 2-and 4-cell stages.The underlying mechanisms of early cell fate determination have long been an important research topic.In this review,we summarize the molecular events that occur during early embryogenesis,as well as the current understanding of their regulatory roles in cell fate decisions.Moreover,as powerful tools for early embryogenesis research,single-cell omics techniques have been applied to both mouse and human preimplantation embryos and have contributed to the discovery of cell fate regulators.Here,we summarize their applications in the research of preimplantation embryos,and provide new insights and perspectives on cell fate regulation.

Planar cell polarity regulators in asymmetric organogenesis during development and disease

The phenomenon of planar cell polarity is critically required for a myriad of morphogenetic processes in metazoan and is accurately controlled by several conserved modules.Six“core”proteins,including Friz zled,Flamingo(Celsr),Van Gogh(Vangl),Dishevelled,Prickle,and Diego(Ankrd6),are major components of the Wnt/planar cell polarity pathway.The Fat/Dchs protocadherins and the Scrib polarity complex also function to instruct cellular polarization.In vertebrates,all these pathways are essential for tissue and organ morphogenesis,such as neural tube closure,left-right symmetry breaking,heart and gut morphogenesis,lung and kidney branching,stereociliary bundle orientation,and proximal-distal limb elongation.Mutations in planar polarity genes are closely linked to various congenital diseases.Striking advances have been made in deciphering their contribution to the establishment of spatially oriented pattern in developing or gans and the maintenance of tissue homeostasis.The challenge remains to clarify the complex interplay of different polarity pathways in organogenesis and the link of cell polarity to cell fate specification.Inter disciplinary approaches are also important to understand the roles of mechanical forces in coupling cellular polarization and differentiation.This review outlines current advances on planar polarity regulators in asymmetric organ formation,with the aim to identify questions that deserve further investigation.

Comparative architecture in monolithic perovskite/silicon tandem solar cells

Inorganic-organic metal halide perovskite light harvester-based perovskite solar cells(PSCs)with widely tunable bandgap have achieved rapid growth in power conversion efficiency,which exceeds 25%now.It is deliberated that if a semitransparent solar cell made of wider bandgap materials was placed on top of a narrow bandgap materials-based solar cell such as a silicon solar cell,with proper optical and electrical arrangements,the resultant tandem device consisting of two subcells could more effectively utilize the solar spectrum than a single junction solar cell.In a perovskite/silicon tandem solar cell(PSTSC),a semitransparent PSC with a wider bandgap is placed on top of a narrow bandgap silicon solar cell.The PSC efficiently harvests the higher energy photons in the ultraviolet and visible regions of the solar spectrum while the silicon solar cell can convert the photons of the infrared region to power.The PSTSC is proposed as a potential candidate to overcome the Shockley-Queisser limit of single-junction silicon solar cells.Though the theoretical limit of a PSTSC is calculated as~42%,its actual efficiency achieved until now is less than 30%.Therefore,a great scope of research exists in improving the efficiency of PSTSCs.Current issues of stability and upscaling of the device in PSCs are also a matter of concern for PSTSCs.A tandem device consists of multiple parts,and different configurations can be applied,thus tuning the architecture of the device.Altering various parts may result in significant changes in the efficiency of the device.In this review,competing architectures of otherwise comparable devices are compared in terms of photovoltaic properties.Thus,future directions to improve the efficiency of the device based on architecture design are proposed herein.In particular,the influence of the polarity of PSCs and the surface morphology of silicon solar cells(both front and rear)on determining the properties of the PSTSC are discussed.

Microtubule-associated deacetylase HDAC6 promotes angiogenesis by regulating cell migration in an EB1-dependent manner

Angiogenesis,a process by which the preexisting blood vasculature gives rise to new capillary vessels,is associated with a variety of physiologic and pathologic conditions.However,the molecular mechanism underlying this important process remains poorly understood.Here we show that histone deacetylase 6(HDAC6),a microtubule-associated enzyme critical for cell motility,contributes to angiogenesis by regulating the polarization and migration of vascular endothelial cells.Inhibition of HDAC6 activity impairs the formation of new blood vessels in chick embryos and in angioreactors implanted in mice.The requirement for HDAC6 in angiogenesis is corroborated in vitro by analysis of endothelial tube formation and capillary sprouting.Our data further show that HDAC6 stimulates membrane ruffling at the leading edge to promote cell polarization.In addition,microtubule end binding protein 1(EB1)is important for HDAC6 to exert its activity towards the migration of endothelial cells and generation of capillary-like structures.These results thus identify HDAC6 as a novel player in the angiogenic process and offer novel insights into the molecular mechanism governing endothelial cell migration and angiogenesis.

Disruption of Planar Cell Polarity Pathway Attributable to Valproic Acid-Induced Congenital Heart Disease through Hdac3 Participation in Mice

Background： Valproic acid （VPA） exposure during pregnancy has been proven to contribute to congenital heart disease （CHD）. Our previous findings implied that disruption of planar cell polarity （PCP） signaling pathway in cardiomyocytes might be a factor for the cardiac teratogenesis of VPA. In addition, the teratogenic ability of VPA is positively correlated to its histone deacetylase （HDAC） inhibition activity. This study aimed to investigate the effect of the VPA on cardiac morphogenesis, HDAC1/2/3, and PCP key genes （Vangl2/Scrib/Rac 1）, subsequently screening out the specific HDACs regulating PCP pathway. Methods： VPA was administered to pregnant C57BL mice at 700 mg/kg intraperitoneally on embryonic day ! 0.5. Dams were sacrificed on E15.5, and death/absorption rates of embryos were evaluated. Embryonic hearts were observed by hematoxylin-eosin staining to identify cardiac abnormalities. H9C2 cells （undifferentiated rat cardiomyoblasts） were transfected with Hdac1/2/3 specific small interfering RNA （siRNA）. Based on the results of siRNA transfection, cells were transfected with Hdac3 expression plasmid and subsequently mock-treated or treated with 8.0 mmol/L VPA. Hdac1/2/3 as well as Vangl2/Scrib/Racl mRNA and protein levels were determined by real-time quantitative polymerase chain reaction and Western blotting, respectively. Total HDAC activity was detected by colorimetric assay.Results： VPA could induce CHD （P 〈 0.001） and inhibit mRNA or protein expression of Hdac1/2/3 as well as Vangl2/Scrib in fetal hearts, in association with total Hdac activity repression （all P 〈 0.05）. In vitro, Hdac3 inhibition could significantly decrease Vangl2/Scrib expression （P 〈 0.01 ）, while knockdown of Hdac 1/2 had no influence （P 〉 0.05）, VPA exposure dramatically decreased the expression of Vanlg2/Scrib together with Hdac activity （P 〈 0.01 ）, while overexpression of Hdac3 could rescue the VPA-induced inhibition （P 〉 0.05）. Conclusion： VPA could inhibit Hdac1/2/3, Vang12/Scrib, or total Hdac activity both in vitro and in vivo and Hdac3 might participate in the process of VPA-induced cardiac developmental anomalies.

Loss of liver kinase B1 causes planar polarity defects in cochlear hair cells in mice

The tumor suppressor gene liver kinase B1 （LKB1）, also called STKll, encodes a serine/threonine kinase. LKB1 plays crucial roles in cell differentiation, proliferation, and polarity. In this study, LKB1 conditional knockout mice （LKB1pax2 CKO mice） were generated using Pax2-Cre mice to investigate the function of LKB1 in inner ear hair cells during early embryonic period. LKB1Pax2 CKO mice died perinatally. Immunofluorescence and scanning electron microscopy revealed that stereociliary bundles in LKB1Pax2 CKO mice were clustered and misoriented, respectively. Moreover, ectopic distribution of kinocilium bundles resulting from abnormal migration of kinocilium was observed in the mutant mice. The orientation of stereociliary bundles and the migration of kinocilia are critical indicators of planar cell polarity （PCP） of hair cells. LKB1 deficiency in LKB1Pax2 CKO mice thus disrupted hair cell planar polarity during embryonic development. Our results suggest that LKB1 is required in PCP formation in cochlear hair cells in mice.

The septin complex links the catenin complex to the actin cytoskeleton for establishing epithelial cell polarity

Cell polarity is essential for spatially regulating of physiological processes in metazoans by which hormonal stimulation‒secretion coupling is precisely coupled for tissue homeostasis and organ communications.However,the molecular mechanisms underlying epithelial cell polarity establishment remain elusive.Here,we show that septin cytoskeleton interacts with catenin complex to organize a functional domain to separate apical from basal membranes in polarized epithelial cells.Using polarized epithelial cell monolayer as a model system with transepithelial electrical resistance as functional readout,our studies show that septins are essential for epithelial cell polarization.Our proteomic analyses discovered a novel septin‒catenin complex during epithelial cell polarization.The functional relevance of septin‒catenin complex was then examined in three-dimensional(3D)culture in which suppression of septins resulted in deformation of apical lumen in cysts,a hallmark seen in polarity-deficient 3D cultures and animals.Mechanistically,septin cytoskeleton stabilizes the association of adherens catenin complex with actin cytoskeleton,and depletion or disruption of septin cytoskeleton liberates adherens junction and polarity complexes into the cytoplasm.Together,these findings reveal a previously unrecognized role for septin cytoskeleton in the polarization of the apical‒basal axis and lumen formation in polarized epithelial cells.

Planar cell polarity genes, Celsr1-3, in neural development

flamingo is among the ＇core＇ planar cell-polarity genes, protein of which belongs to a unique cadherin subfamily. In contrast to the classic cadherins, composed of several extracellular cadherin repeats, one transmembrane domain and one cytoplasmic segment linked to catenin binding, Drosophila Flamingo has seven transmembrane segments and a cytoplasmic tail with no catenin-binding sequence. In Drosophila, Flamingo has pleotropic roles in controlling epithelial polarity and neuronal morphogenesis. Three mammalian orthologs of flamingo, Celsrl-3, are widely expressed in the nervous system. Recent work has shown that Celsrl-3 play important roles in neural development, such as in axon guidance, neuronal migration, and cilium polarity. CeIsrl-3 single-gene knockout mice exhibit different phenotypes, but there are cooperative interactions among these genes.