Search

The epidermis is the outermost layer of the skin and the body’s primary barrier to external pathogens; however, the early epidermal immune response remains to be mechanistically understood. We show that the chemokine CXCL14, produced by epidermal keratinocytes, exhibits robust circadian fluctuations and initiates innate immunity. Clearance of the skin pathogen Staphylococcus aureus in nocturnal mice was associated with CXCL14 expression, which was high during subjective daytime and low at night. In contrast, in marmosets, a diurnal primate, circadian CXCL14 expression was reversed. Rhythmically expressed CXCL14 binds to S. aureus DNA and induces inflammatory cytokine production by activating Toll-like receptor (TLR)9-dependent innate pathways in dendritic cells and macrophages underneath the epidermis. CXCL14 also promoted phagocytosis by macrophages in a TLR9-independent manner. These data indicate that circadian production of the epidermal chemokine CXCL14 rhythmically suppresses skin bacterial proliferation in mammals by activating the innate immune system., 体内時計は夜間に自然免疫を発動 --皮膚ケモカインによる自然免疫機構--. 京都大学プレスリリース. 2022-06-16., Biological clocks set for skin immunity. 京都大学プレスリリース. 2022-06-21.

CXCL14 is a primordial chemokine that plays multiple roles in tumor suppression, autoimmune arthritis, and obesity-associated insulin resistance. However, the underlying molecular mechanisms are unclear. Here, we show that CXCL14 transports various types of CpG oligodeoxynucleotide (ODN) into the endosomes and lysosomes of bone marrow-derived dendritic cells (DCs), thereby activating Toll-like receptor 9 (TLR9). A combination of CpG ODN (ODN2395) plus CXCL14 induced robust production of IL-12 p40 by wild-type, but not Tlr9-knockout, DCs. Consistent with this, ODN2395-mediated activation of DCs was significantly attenuated in Cxcl14-knockout mice. CXCL14 bound CpG ODN with high affinity at pH 7.5, but not at pH 6.0, thereby enabling efficient delivery of CpG ODN to TLR9 in the endosome/lysosome. Furthermore, the CXCL14-CpG ODN complex specifically bound to high affinity CXCL14 receptors on DCs. Thus, CXCL14 serves as a specific carrier of CpG DNA to sensitize TLR9-mediated immunosurveillance., Highlights • CXCL14 specifically binds CpG DNA with high affinity. • CXCL14/CpG DNA complex is efficiently transported into dendritic cells. • CXCL14/CpG DNA induces cytokine production via Toll-like receptor 9. We discovered that CXCL14 specifically binds CpG DNAs with high affinity and transports them into the endosomes and lysosomes of dendritic cells (DCs). Consequently, Toll-like receptor 9 (Tlr9) in DCs was activated, thereby leading to robust production of IL-12 p40 and IL-6. These activities of CXCL14 were not observed in Tlr9-deficient DCs. Moreover, CpG DNA (ODN2395)-mediated activation of DCs was significantly attenuated in Cxcl14-knockout mice. Therefore, CXCL14 plays an important role in the Tlr9-mediated immunosurveillance against pathogens and cancers. From the clinical point of view, CXCL14/CpG DNA could be useful as a new type of vaccine adjuvant.

We carried out liquid chromatography-tandem mass spectrometry analysis of metabolites in mice. Those metabolome data showed that hepatic glucose content is reduced, but that brain glucose content is unaffected, during fasting, consistent with the priority given to brain glucose consumption during fasting. The molecular mechanisms for this preferential glucose supply to the brain are not fully understood. We also showed that the fasting-induced production of the ketone body β-hydroxybutyrate (β-OHB) enhances expression of the glucose transporter gene Slc2a1 (Glut1) via histone modification. Upon β-OHB treatment, Slc2a1 expression was up-regulated, with a concomitant increase in H3K9 acetylation at the critical cis-regulatory region of the Slc2a1 gene in brain microvascular endothelial cells and NB2a neuronal cells, shown by quantitative PCR analysis and chromatin immunoprecipitation assay. CRISPR/Cas9-mediated disruption of the Hdac2 gene increased Slc2a1 expression, suggesting that it is one of the responsible histone deacetylases (HDACs). These results confirm that β-OHB is a HDAC inhibitor and show that β-OHB plays an important role in fasting-induced epigenetic activation of a glucose transporter gene in the brain.

Latrophilin2 (Lphn2) is an adhesion-class of G protein-coupled receptor with an unknown function in development. Here, we show that Xenopus laevis lphn2 (Xlphn2) is involved in the migration and differentiation of neural crest (NC) cells and placode patterning in Xenopus laevis embryos. Although Xlphn2 mRNA was detected throughout embryogenesis, it was expressed more abundantly in the placode region. Morpholino antisense oligonucleotide-mediated knockdown of Xlphn2 caused abnormal migration of NC cells, irregular epibranchial placode segmentation, and defective cartilage formation. Transplantation of fluorescently-labeled NC regions of wild-type embryos into Xlphn2 morpholino-injected embryos reproduced the defective NC cell migration, indicating that Xlphn2 regulates the migration of NC cells in a non-cell autonomous manner. Our results suggest that Xlphn2 is essential for placode patterning and as a guidance molecule for NC cells.

Activation of the CXCL12–CXCR4 pathway is crucial for the migration of hematopoietic stem cells, various immune cells, and malignant tumor cells. Here, we show that another CXC chemokine, CXCL14, specifically binds to CXCR4 with high affinity and inhibits the CXCL12-mediated chemotaxis of human leukemia-derived cell lines and CD34+ hematopoietic progenitor cells. Thus, CXCL14 functions as a natural inhibitor of CXCL12. Our observations suggest that CXCL14 represents, along with CXCR7, molecules that co-evolved with the CXCL12–CXCR4 axis to modulate important physiological processes in development, stem cell maintenance, and immune responses.Structured summary of protein interactionsCXCR4 physically interacts with CXCL14 anti bait coimmunoprecipitation by (View interaction).

CXCL14 is a member of the CXC chemokine family. CXCL14 possesses chemoattractive activity for activated macrophages, immature dendritic cells and natural killer cells. CXCL14-deficient mice do not exhibit clear immune system abnormalities, suggesting that the function of CXCL14 can be compensated for by other chemokines. However, CXCL14 does appear to have unique biological roles. It suppresses the in vivo growth of lung and head-and-neck carcinoma cells, whereas the invasiveness of breast and prostate cancer cells appears to be promoted by CXCL14. Moreover, recent evidence revealed that CXCL14 participates in glucose metabolism, feeding behaviour-associated neuronal circuits, and anti-microbial defense. Based on the expression patterns of CXCL14 and CXCL12 during embryonic development and in the perinatal brain in mice, the functions of these two chemokines may be opposite or interactive. Although CXCL14 receptors have not yet been identified, the intracellular activity of CXCL14 in breast cancer cells suggests that the CXCL14 receptor(s) and signal transduction pathway(s) may be different from those of conventional CXC-type chemokines.

Leucine-rich repeats and immunoglobulin-like domains 3(Lrig3) was identified by microarray analysis among genes that show differential expression during gastrulation in Xenopus laevis. Lrig3 was expressed in the neural plate and neural crest (NC) at neurula stages, and in NC derivatives and other dorsal structures during tailbud stages. A prominent consequence of the morpholino-induced inhibition of Lrig3 expression was impaired NC formation, as revealed by the suppression of marker genes, including Slug, Sox9 and Foxd3. In the NC induction assay involving Chordin plus Wnt3a-injected animal caps, Lrig3 morpholino inhibited expression of Slug, Sox9 and Foxd3, but not of Pax3 and Zic1. In line with this, Lrig3 knockdown prevented NC marker induction by Pax3 and Zic1, suggesting that Lrig3 acts downstream of these two genes in NC formation. Injection of Lrig3 and Wnt3a led to low-level induction of NC markers and enhanced induction of Fgf3,Fgf4 and Fgf8 in animal caps, suggesting a positive role for Lrig3 in Wnt signaling. Lrig3 could attenuate Fgf signaling in animal caps,did interact with Fgf receptor 1 in cultured cells and, according to context,decreased or increased the induction of NC markers by Fgf. We suggest that Lrig3 functions in NC formation in Xenopus by modulating the Wnt and Fgf signaling pathways.

The Wnt–PCP (planar cell polarity, PCP) pathway regulates cell polarity and convergent extension movements during axis formation in vertebrates by activation of Rho and Rac, leading to the re-organization of the actin cytoskeleton. Rho and Rac activation require guanine nucleotide-exchange factors (GEFs), but the identity of the GEF involved in Wnt–PCP-mediated convergent extension is unknown. Here we report the identification of the weak-similarity GEF (WGEF) gene by a microarray-based screen for notochord enriched genes, and show that WGEF is involved in Wnt-regulated convergent extension. Overexpression of WGEF activated RhoA and rescued the suppression of convergent extension by dominant-negative Wnt-11, whereas depletion of WGEF led to suppression of convergent extension that could be rescued by RhoA or Rho-associated kinase activation. WGEF protein preferentially localized at the plasma membrane, and Frizzled-7 induced colocalization of Dishevelled and WGEF. WGEF protein can bind to Dishevelled and Daam-1, and deletion of the Dishevelled-binding domain generates a hyperactive from of WGEF. These results indicate that WGEF is a component of the Wnt–PCP pathway that connects Dishevelled to Rho activation.

The Spemann organizer secretes several antagonists of growth factors during gastrulation. We describe a novel secreted protein, Mig30, which is expressed in the anterior endomesoderm of the Spemann organizer. Mixer-inducible gene 30 (Mig30) was isolated as a target of Mixer, a homeobox gene required for endoderm development. The Mig30 gene encodes a secreted protein containing a cysteine-rich domain and an immunoglobulin-like domain that belongs to the insulin-like growth factor-binding protein family. Overexpression of Mig30 in the dorsal region results in the retardation of morphogenetic movements during gastrulation and leads to microcephalic embryos. Overexpression of Mig30 also inhibits activin-induced elongation of ectodermal explants without affecting gene expression patterns in mesoderm and endoderm. These results suggest that Mig30 is involved in the regulation of morphogenetic movements during gastrulation in the extracellular space of the Spemann organizer.

CXCL12 and CXCL14 are evolutionarily conserved members of the CXC-type chemokine family. CXCL12 binds specifically to the G-protein-coupled receptor CXCR4 to induce the migration of primordial germ cells, hematopoietic stem cells, and inflammation-associated immune cells. In addition, CXCL12-CXCR4 signaling is often enhanced in malignant tumor cells and facilitates increased proliferation as well as metastasis. Although macrophage migration inhibitory factor and extracellular ubiquitin interact with CXCR4 as agonistic factors, CXCL12 was believed to be the sole chemokine ligand for CXCR4. However, a very recent report revealed that CXCL14 binds to CXCR4 with high affinity and efficiently inhibits CXCL12-mediated chemotaxis of hematopoietic progenitor and leukemia-derived cells. CXCL14 does not directly cross-compete with CXCL12 for the CXCR4 binding but instead inactivates CXCR4 via receptor internalization. Because both CXCL12 and CXCL14 are expressed during embryogenesis and brain development in mice, these two chemokines could function in an interactive fashion. We propose that the CXCL14 gene has been conserved from fish to man due to its role in fine-tuning the strength of CXCL12-mediated signal transduction. In addition to its biological implications, the above finding will be important for designing anti-cancer compounds targeting the CXCL12-CXCR4 signaling axis. In fact, a stabilized dimeric peptide containing the C-terminal 51–77 amino acid residues of CXCL14 has been shown to have stronger CXCL12 antagonistic activity than full-length CXCL14.

CXCL14 is a primordial CXC-type chemokine that induces migration of immature dendritic cells (DCs), tissue resident macrophages, and natural killer cells. It has been reported that CXCL14 plays multiple roles in tumor suppression, exacerbation of autoimmune arthritis, and induction of obesity-associated insulin resistance. However, underlying molecular mechanisms of these phenomena remain to be elucidated. Although CXCL14 binds to the CXCL12 receptor CXCR4 with high affinity, chemoattractive activity of CXCL14 is much weaker than CXCL12. In this study, we newly discovered that CXCL14 specifically binds to CpG DNA and activates Toll-like receptor 9 (TLR9), thereby inducing inflammatory cytokines such as IL-6, IL-12 p40, and TNFa in mouse bone marrow-derived dendritic cells (BMDCs). Cell surface expression levels of MHC class-II and CD86 in BMDCs were also enhanced by the combination of CpG DNA and CXCL14. In this experimental setting, CXCL14 interacted with certain classes of CpG DNA, but not with RNA ligands for TLR3 and TLR8. In addition, this CpG DNA-cooperative activity was not present in CXCL8 and CXCL12, excluding a nonspecific interaction between CpG DNA and an alkaline chemokine. In BMDCs and inguinal lymph node DCs, intracellular transport of a low concentration of CpG DNA was greatly enhanced by the addition of CXCL14. Confocal microscopical analyses revealed that CpG DNA and CXCL14 mainly co-localized in EEA1+ endosome and LAMP1+ lysosomal compartments where TLR9 is present. Furthermore, we demonstrated that CXCL14 binds to CpG DNA in vitro in the neutral pH condition with high affinity (Kd=9.8 nM). This interaction was completely dissociated in pH 6.0, implying that CpG DNA can be released and passed to TLR9 in the endosome and lysosome. Consistent with our hypothesis, induction of IL-12 p40, MHC class-II, and CD86 by the combination of CpG DNA and CXCL14 was not observed in BMDCs derived from TLR9 knockout (KO) mice. Moreover, after systemic administration of CpG DNA, plasma concentration of IL-12 p40 and frequency of MHC-class II+CD11c+CD8+DCs in spleen were significantly decreased in CXCL14-deficient mice when compared to littermate control mice. Taken together, these results demonstrated that CXCL14 serves as a specific carrier for CpG DNA into conventional DCs for activating TLR9-mediated adaptive immune system. This is also the first demonstration of a DNA sensing function of chemokine. The combination of CXCL14 and CpG DNA would be a promising vaccine adjuvant for enhancing immnunosurveillance against pathogens and malignant cancers. Disclosures Tanegashima: Tokyo Metropolitan Institute of Medical Science: Patents & Royalties. Takahashi:Tokyo Metropolitan Institute of Medical Science: Patents & Royalties. Tsuji:Tokushima University: Patents & Royalties. Shigenaga:Tokushima University: Patents & Royalties. Otaka:Tokushima University: Patents & Royalties.

We recently reported that CXCL14 binds to CXCR4 with high affinity and inhibits CXCL12-mediated chemotaxis. Here we found that the C-terminal 51–77 amino acid residues of CXCL14 are responsible for CXCR4 binding. A disulfide dimer peptide of CXCL14(51–77) bound to CXCR4 with comparable affinity to full length CXCL14, and exhibited CXCL12 inhibitor activity. CXCR4 was efficiently internalized upon binding of dimeric CXCL14(51–77), thereby being reduced on the cell surface. Substitution of 5 amino acid residues in combination with the use of an oxime linker for dimerization increased the solubility and chemical stability of the dimeric CXCL14(51–77).

BACKGROUND: CXCL14 is a chemoattractant for macrophages and immature dendritic cells. We recently reported that CXCL14-deficient (CXCL14(-/-)) female mice in the mixed background are protected from obesity-induced hyperglycemia and insulin resistance. The decreased macrophage infiltration into visceral adipose tissues and the increased insulin sensitivity of skeletal muscle contributed to these phenotypes. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we performed a comprehensive study for the body weight control of CXCL14(-/-) mice in the C57BL/6 background. We show that both male and female CXCL14(-/-) mice have a 7-11% lower body weight compared to CXCL14(+/-) and CXCL14(+/+) mice in adulthood. This is mainly caused by decreased food intake, and not by increased energy expenditure or locomotor activity. Reduced body weight resulting from the CXCL14 deficiency was more pronounced in double mutant CXCL14(-/-)ob/ob and CXCL14(-/-)A(y) mice. In the case of CXCL14(-/-)A(y) mice, oxygen consumption was increased compared to CXCL14(+/-)A(y) mice, in addition to the reduced food intake. In CXCL14(-/-) mice, fasting-induced up-regulation of Npy and Agrp mRNAs in the hypothalamus was blunted. As intracerebroventricular injection of recombinant CXCL14 did not change the food intake of CXCL14(-/-) mice, CXCL14 could indirectly regulate appetite. Intriguingly, the food intake of CXCL14(-/-) mice was significantly repressed when mice were transferred to a novel environment. CONCLUSIONS/SIGNIFICANCE: We demonstrated that CXCL14 is involved in the body weight control leading to the fully obese phenotype in leptin-deficient or A(y) mutant mice. In addition, we obtained evidence indicating that CXCL14 may play an important role in central nervous system regulation of feeding behavior.

We compared the transcriptome in the developing notochord of Xenopus laevis embryos with that of other embryonic regions. A coordinated and intense activation of a large set of secretory pathway genes was observed in the notochord, but not in notochord precursors in the axial mesoderm at early gastrula stage. The genes encoding Xbp1 and Creb3l2 were also activated in the notochord. These two transcription factors are implicated in the activation of secretory pathway genes during the unfolded protein response, where cells react to the stress of a build-up of unfolded proteins in their endoplasmic reticulum. Xbp1 and Creb3l2 are differentially expressed but not differentially activated in the notochord. Reduction of expression of Xbp1 or Creb3l2 by injection of antisense morpholinos led to strong deficits in notochord but not somitic muscle development. In addition, the expression of some, but not all, genes encoding secretory proteins was inhibited by injection of xbp1 morpholinos. Furthermore, expression of activated forms of Xbp1 or Creb3l2 in animal explants could activate a similar subset of secretory pathway genes. We conclude that coordinated activation of a battery of secretory pathway genes mediated by Xbp1 and Creb/ATF factors is a characteristic and necessary feature of notochord formation.