DSCAM Deficiency Leads to Premature Spine Maturation and Autism-like Behaviors.

Mutations in some cell adhesion molecules (CAMs) cause abnormal synapse formation and maturation, and serve as one of the potential mechanisms of autism spectrum disorders (ASDs). Recently, DSCAM (Down syndrome cell adhesion molecule) was found to be a high-risk gene for autism. However, it is still unclear how DSCAM contributes to ASD. Here, we show that DSCAM expression was downregulated following synapse maturation, and that DSCAM deficiency caused accelerated dendritic spine maturation during early postnatal development. Mechanistically, the extracellular domain of DSCAM interacts with neuroligin1 (NLGN1) to block the NLGN1-neurexin1ß (NRXN1ß) interaction. DSCAM extracellular domain was able to rescue spine overmaturation in DSCAM knockdown neurons. Precocious spines in DSCAM-deficient mice showed increased glutamatergic transmission in the developing cortex and induced autism-like behaviors, such as social novelty deficits and repetitive behaviors. Thus, DSCAM might be a repressor that prevents premature spine maturation and excessive glutamatergic transmission, and its deficiency could lead to autism-like behaviors. Our study provides new insight into the potential pathophysiological mechanisms of ASDs.SIGNIFICANCE STATEMENTDSCAM is not only associated with Down syndrome but is also a strong autism risk gene based on large-scale sequencing analysis. However, it remains unknown exactly how DSCAM contributes to autism. In mice, either neuron- and astrocyte-specific or pyramidal neuron-specific DSCAM deficiencies resulted in autism-like behaviors and enhanced spatial memory. In addition, DSCAM knockout or knockdown in pyramidal neurons led to increased dendritic spine maturation. Mechanistically, the extracellular domain of DSCAM binds to NLGN1 and inhibits NLGN1-NRXN1ß interaction, which can rescue abnormal spine maturation induced by DSCAM deficiency. Our research demonstrates that DSCAM negatively modulates spine maturation, and that DSCAM deficiency leads to excessive spine maturation and autism-like behaviors, thus providing new insight into a potential pathophysiological mechanism of autism.

EDIL3 deficiency ameliorates adverse cardiac remodelling by neutrophil extracellular traps (NET)-mediated macrophage polarization.

AIMS: After myocardial infarction (MI), injured cardiomyocytes recruit neutrophils and monocytes/macrophages to myocardium, which in turn initiates inflammatory and reparative cascades, respectively. Either insufficient or excessive inflammation impairs cardiac healing. As an endogenous inhibitor of neutrophil adhesion, EDIL3 plays a crucial role in inflammatory regulation. However, the role of EDIL3 in MI remains obscure. We aimed to define the role of EDIL3 in cardiac remodelling after MI. METHODS AND RESULTS: Serum EDIL3 levels in MI patients were negatively associated with MI biomarkers. Consistently, WT mice after MI showed low levels of cardiac EDIL3. Compared with WT mice, Edil3-/- mice showed improvement of post-MI adverse remodelling, as they exhibited lower mortality, better cardiac function, shorter scar length, and smaller LV cavity. Accordingly, infarcted hearts of Edil3-/- mice contained fewer cellular debris and lower amounts of fibrosis content, with decreased collagen I/III expression and the percentage of α-smooth muscle actin myofibroblasts. Mechanistically, EDIL3 deficiency did not affect the recruitment of monocytes or T cells, but enhanced neutrophil recruitment and following expansion of pro-inflammatory Mertk-MHC-IIlo-int (myeloid-epithelial-reproductive tyrosine kinase/major histocompatibility complex II) macrophages. The injection of neutrophil-specific C-X-C motif chemokine receptor 2 antagonist eliminated the differences in macrophage polarization and cardiac function between WT and Edil3-/- mice after MI. Neutrophil extracellular traps (NETs), which were more abundant in the hearts of Edil3-/- mice, contributed to Mertk-MHC-IIlo-int polarization via Toll-like receptor 9 pathway. The inhibition of NET formation by treatment of neutrophil elastase inhibitor or DNase I impaired macrophage polarization, increased cellular debris and aggravated cardiac adverse remodelling, thus removed the differences of cardiac function between WT and Edil3-/- mice. Totally, EDIL3 plays an important role in NET-primed macrophage polarization and cardiac remodelling during MI. CONCLUSION: We not only reveal that EDIL3 deficiency ameliorates adverse cardiac healing via NET-mediated pro-inflammatory macrophage polarization but also discover a new crosstalk between neutrophil and macrophage after MI.

Age-related degradation of tectorial membrane dynamics with loss of CEACAM16.

Studies of genetic disorders of sensorineural hearing loss have been instrumental in delineating mechanisms that underlie the remarkable sensitivity and selectivity that are hallmarks of mammalian hearing. For example, genetic modifications of TECTA and TECTB, which are principal proteins that comprise the tectorial membrane (TM), have been shown to alter auditory thresholds and frequency tuning in ways that can be understood in terms of changes in the mechanical properties of the TM. Here, we investigate effects of genetic modification targeting CEACAM16, a third important TM protein. Loss of CEACAM16 has been recently shown to lead to progressive reductions in sensitivity. Whereas age-related hearing losses have previously been linked to changes in sensory receptor cells, the role of the TM in progressive hearing loss is largely unknown. Here, we show that TM stiffness and viscosity are significantly reduced in adult mice that lack functional CEACAM16 relative to age-matched wild-type controls. By contrast, these same mechanical properties of TMs from juvenile mice that lack functional CEACAM16 are more similar to those of wild-type mice. Thus, changes in hearing phenotype align with changes in TM material properties and can be understood in terms of the same TM wave properties that were previously used to characterize modifications of TECTA and TECTB. These results demonstrate that CEACAM16 is essential for maintaining TM mechanical and wave properties, which in turn are necessary for sustaining the remarkable sensitivity and selectivity of mammalian hearing with increasing age.

MIR21-induced loss of junctional adhesion molecule A promotes activation of oncogenic pathways, progression and metastasis in colorectal cancer.

Junctional adhesion molecules (JAMs) play a critical role in cell permeability, polarity and migration. JAM-A, a key protein of the JAM family, is altered in a number of conditions including cancer; however, consequences of JAM-A dysregulation on carcinogenesis appear to be tissue dependent and organ dependent with significant implications for the use of JAM-A as a biomarker or therapeutic target. Here, we test the expression and prognostic role of JAM-A downregulation in primary and metastatic colorectal cancer (CRC) (n = 947). We show that JAM-A downregulation is observed in ~60% of CRC and correlates with poor outcome in four cohorts of stages II and III CRC (n = 1098). Using JAM-A knockdown, re-expression and rescue experiments in cell line monolayers, 3D spheroids, patient-derived organoids and xenotransplants, we demonstrate that JAM-A silencing promotes proliferation and migration in 2D and 3D cell models and increases tumour volume and metastases in vivo. Using gene-expression and proteomic analyses, we show that JAM-A downregulation results in the activation of ERK, AKT and ROCK pathways and leads to decreased bone morphogenetic protein 7 expression. We identify MIR21 upregulation as the cause of JAM-A downregulation and show that JAM-A rescue mitigates the effects of MIR21 overexpression on cancer phenotype. Our results identify a novel molecular loop involving MIR21 dysregulation, JAM-A silencing and activation of multiple oncogenic pathways in promoting invasiveness and metastasis in CRC.

Periostin deficiency attenuates lipopolysaccharide- and obesity-induced adipose tissue fibrosis.

Periostin (POSTN) is a type of matricellular protein, but its functions in adipose fibrosis remain unclear. Here, we found that POSTN expression is significantly increased in mouse adipose tissue after treatment with lipopolysaccharide (LPS) or a high-fat diet (HFD) and that adipose progenitor cells are the main source of POSTN. In our mouse model of fibrosis, POSTN deletion protected mice from adipose fibrosis, probably through reducing the accumulation of macrophages and promoting adipocyte differentiation of progenitor cells. Taken together, our study demonstrates that POSTN deficiency attenuates adipose tissue fibrosis and improves insulin resistance, providing new insights into the diagnosis and treatment of type II diabetes by targeting adipose tissue fibrosis.

CDCP1 on Dendritic Cells Contributes to the Development of a Model of Kawasaki Disease.

The etiology and pathology of Kawasaki disease (KD) remain elusive. Cub domain-containing protein 1 (CDCP1), a cell-surface protein that confers poor prognosis of patients with certain solid tumors, was recently identified as one of the most significantly upregulated genes in SARS-CoV-2-infected children who developed systemic vasculitis, a hallmark of KD. However, a potential role of CDCP1 in KD has not previously been explored. In this study, we found that CDCP1 knockout (KO) mice exhibited attenuated coronary and aortic vasculitis and decreased serum Candida albicans water-soluble fraction (CAWS)-specific IgM/IgG2a and IL-6 concentrations compared with wild-type mice in an established model of KD induced by CAWS administration. CDCP1 expression was not detectable in cardiomyocytes, cardio fibroblasts, or coronary endothelium, but constitutive expression of CDCP1 was observed on dendritic cells (DCs) and was upregulated by CAWS stimulation. CAWS-induced IL-6 production was significantly reduced in CDCP1 KO DCs, in association with impaired Syk-MAPK signaling pathway activation. These novel findings suggest that CDCP1 might regulate KD development by modulating IL-6 production from DCs via the Syk-MAPK signaling pathway.

MAGI1 inhibits the AMOTL2/p38 stress pathway and prevents luminal breast tumorigenesis.

Alterations to cell polarization or to intercellular junctions are often associated with epithelial cancer progression, including breast cancers (BCa). We show here that the loss of the junctional scaffold protein MAGI1 is associated with bad prognosis in luminal BCa, and promotes tumorigenesis. E-cadherin and the actin binding scaffold AMOTL2 accumulate in MAGI1 deficient cells which are subjected to increased stiffness. These alterations are associated with low YAP activity, the terminal Hippo-pathway effector, but with an elevated ROCK and p38 Stress Activated Protein Kinase activities. Blocking ROCK prevented p38 activation, suggesting that MAGI1 limits p38 activity in part through releasing actin strength. Importantly, the increased tumorigenicity of MAGI1 deficient cells is rescued in the absence of AMOTL2 or after inhibition of p38, demonstrating that MAGI1 acts as a tumor-suppressor in luminal BCa by inhibiting an AMOTL2/p38 stress pathway.

Differential Contribution of Cadm1-Cadm3 Cell Adhesion Molecules to Peripheral Myelinated Axons.

Cell adhesion proteins of the Cadm (SynCAM/Necl) family regulate myelination and the organization of myelinated axons. In the peripheral nervous system (PNS), intercellular contact between Schwann cells and their underlying axons is believed to be mediated by binding of glial Cadm4 to axonal Cadm3 or Cadm2. Nevertheless, given that distinct neurons express different combinations of the Cadm proteins, the identity of the functional axonal ligand for Cadm4 remains to be determined. Here, we took a genetic approach to compare the phenotype of Cadm4 null mice, which exhibit abnormal distribution of Caspr and Kv1 potassium channels, with mice lacking different combinations of Cadm1-Cadm3 genes. We show that in contrast to mice lacking the single Cadm1, Cadm2, or Cadm3 genes, genetic ablation of all three phenocopies the abnormalities detected in the absence of Cadm4. Similar defects were observed in double mutant mice lacking Cadm3 and Cadm2 (i.e., Cadm3-/-/Cadm2-/-) or Cadm3 and Cadm1 (i.e., Cadm3-/-/Cadm1-/-), but not in mice lacking Cadm1 and Cadm2 (i.e., Cadm1-/-/Cadm2-/-). Furthermore, axonal organization abnormalities were also detected in Cadm3 null mice that were heterozygous for the two other axonal Cadms. Our results identify Cadm3 as the main axonal ligand for glial Cadm4, and reveal that its absence could be compensated by the combined action of Cadm2 and Cadm1.SIGNIFICANCE STATEMENT Myelination by Schwann cells enables fast conduction of action potentials along motor and sensory axons. In these nerves, Schwann cell-axon contact is mediated by cell adhesion molecules of the Cadm family. Cadm4 in Schwann cells regulates axonal ensheathment and myelin wrapping, as well as the organization of the axonal membrane, but the identity of its axonal ligands is not clear. Here, we reveal that Cadm mediated axon-glia interactions depend on a hierarchical adhesion code that involves multiple family members. Our results provide important insights into the molecular mechanisms of axon-glia communication, and the function of Cadm proteins in PNS myelin.

Functional investigation of the coronary artery disease gene SVEP1.

A missense variant of the sushi, von Willebrand factor type A, EGF and pentraxin domain containing protein 1 (SVEP1) is genome-wide significantly associated with coronary artery disease. The mechanisms how SVEP1 impacts atherosclerosis are not known. We found endothelial cells (EC) and vascular smooth muscle cells to represent the major cellular source of SVEP1 in plaques. Plaques were larger in atherosclerosis-prone Svep1 haploinsufficient (ApoE-/-Svep1+/-) compared to Svep1 wild-type mice (ApoE-/-Svep1+/+) and ApoE-/-Svep1+/- mice displayed elevated plaque neutrophil, Ly6Chigh monocyte, and macrophage numbers. We assessed how leukocytes accumulated more inside plaques in ApoE-/-Svep1+/- mice and found enhanced leukocyte recruitment from blood into plaques. In vitro, we examined how SVEP1 deficiency promotes leukocyte recruitment and found elevated expression of the leukocyte attractant chemokine (C-X-C motif) ligand 1 (CXCL1) in EC after incubation with missense compared to wild-type SVEP1. Increasing wild-type SVEP1 levels silenced endothelial CXCL1 release. In line, plasma Cxcl1 levels were elevated in ApoE-/-Svep1+/- mice. Our studies reveal an atheroprotective role of SVEP1. Deficiency of wild-type Svep1 increased endothelial CXCL1 expression leading to enhanced recruitment of proinflammatory leukocytes from blood to plaque. Consequently, elevated vascular inflammation resulted in enhanced plaque progression in Svep1 deficiency.

Desert Hedgehog-Driven Endothelium Integrity Is Enhanced by Gas1 (Growth Arrest-Specific 1) but Negatively Regulated by Cdon (Cell Adhesion Molecule-Related/Downregulated by Oncogenes).

OBJECTIVE: Evidences accumulated within the past decades identified hedgehog signaling as a new regulator of endothelium integrity. More specifically, we recently identified Dhh (desert hedgehog) as a downstream effector of Klf2 (Kruppel-like factor 2) in endothelial cells (ECs). The purpose of this study is to investigate whether hedgehog coreceptors Gas1 (growth arrest-specific 1) and Cdon (cell adhesion molecule-related/downregulated by oncogenes) may be used as therapeutic targets to modulate Dhh signaling in ECs. Approach and Results: We demonstrated that both Gas1 and Cdon are expressed in adult ECs and relied on either siRNAs- or EC-specific conditional knockout mice to investigate their role. We found that Gas1 deficiency mainly phenocopies Dhh deficiency especially by inducing VCAM-1 (vascular cell adhesion molecule 1) and ICAM-1 (intercellular adhesion molecule 1) overexpression while Cdon deficiency has opposite effects by promoting endothelial junction integrity. At a molecular level, Cdon prevents Dhh binding to Ptch1 (patched-1) and thus acts as a decoy receptor for Dhh, while Gas1 promotes Dhh binding to Smo (smoothened) and as a result potentiates Dhh effects. Since Cdon is upregulated in ECs treated by inflammatory cytokines, including TNF (tumor necrosis factor)-α and Il (interleukin)-1ß, we then tested whether Cdon inhibition would promote endothelium integrity in acute inflammatory conditions and found that both fibrinogen and IgG extravasation were decreased in association with an increased Cdh5 (cadherin-5) expression in the brain cortex of EC-specific Cdon knockout mice administered locally with Il-1ß. CONCLUSIONS: Altogether, these results demonstrate that Gas1 is a positive regulator of Dhh in ECs while Cdon is a negative regulator. Interestingly, Cdon blocking molecules may then be used to promote endothelium integrity, at least in inflammatory conditions.

The erythroblastic island niche: modeling in health, stress, and disease.

Erythropoiesis is one of the most demanding processes in the body, with more than 2 million red blood cells produced every second. Multiple hereditary and acquired red blood cell disorders arise from this complex system, with existing treatments effective in managing some of these conditions but few offering a long-term cure. Finding new treatments relies on the full understanding of the cellular and molecular interactions associated with the production and maturation of red blood cells, which take place within the erythroblastic island niche. The elucidation of processes associated within the erythroblastic island niche in health and during stress erythropoiesis has relied on in vivo modeling in mice, with complexities dissected using simple in vitro systems. Recent progress using state-of-the-art stem cell technology and gene editing has enabled a more detailed study of the human niche. Here, we review these different models and describe how they have been used to identify and characterize the cellular and molecular pathways associated with red blood cell production and maturation. We speculate that these systems could be applied to modeling red blood cell diseases and finding new druggable targets, which would prove especially useful for patients resistant to existing treatments. These models could also aid in research into the manufacture of red blood cells in vitro to replace donor blood transfusions, which is the most common treatment of blood disorders.

Close homolog of L1-deficient ameliorates inflammatory bowel disease by regulating the balance of Th17/Treg.

OBJECTIVE: The aim of this study is to investigate the role of close homolog of L1 (CHL1) on inflammatory bowel disease (IBD), and the correlation with the balance of Th17/Treg. METHODS: Dextran sodium sulfate (DSS)-induced IBD mice model was established. CHL1 knockout (KO) mice and CHL1 wild-type (WT) mice were subjected to DSS. CHL1 expression was detected using qRT-PCR. Weight was recorded daily, and disease activity index (DAI) score was assessed. The colon length and histological changes were measured. The number of neutrophils, macrophages and T cells was observed by immunohistochemistry. The expression of inflammatory cytokines and the proportion of Th17/Treg cells were detected by qRT-PCR and flow cytometry. The expression of RORγt, STAT3 and Foxp3 was detected by using immunohistochemistry and Western blot. RESULTS: CHL1 expression was upregulated in DSS-induced IBD mice. DSS-CHLl-KO mice exhibited less weight loss than the DSS-CHLl-WT mice. The DAI score and histological score were decreased in DSS-CHLl-KO mice compared with DSS-CHLl-WT mice, while colon length was increased. Number of neutrophils, macrophages and T cells, and expression of TNF-α, IL-6, IL-17A, IL-21 and IL-23 were decreased in DSS-CHLl-KO mice, while IL-10 expression was increased. Moreover, CHL1-deficient inhibited Th17 cells differentiation and promoted Treg cells differentiation in IBD mice. CHL1-deficient also inhibited the expression of RORγt and STAT3, and promoted the expression of Foxp3 in IBD mice. CONCLUSION: CHL1-deficient reduces the inflammatory response by regulating the balance of Th17/Treg in mice with IBD. CHL1 is expected to be a new target for the treatment of IBD.

Blocking integrin α4ß7-mediated CD4 T cell recruitment to the intestine and liver protects mice from western diet-induced non-alcoholic steatohepatitis.

BACKGROUND & AIMS: The heterodimeric integrin receptor α4ß7 regulates CD4 T cell recruitment to inflamed tissues, but its role in the pathogenesis of non-alcoholic steatohepatitis (NASH) is unknown. Herein, we examined the role of α4ß7-mediated recruitment of CD4 T cells to the intestine and liver in NASH. METHODS: Male littermate F11r+/+ (control) and junctional adhesion molecule A knockout F11r-/- mice were fed a normal diet or a western diet (WD) for 8 weeks. Liver and intestinal tissues were analyzed by histology, quantitative reverse transcription PCR (qRT-PCR), 16s rRNA sequencing and flow cytometry. Colonic mucosa-associated microbiota were analyzed using 16s rRNA sequencing. Liver biopsies from patients with NASH were analyzed by confocal imaging and qRT-PCR. RESULTS: WD-fed knockout mice developed NASH and had increased hepatic and intestinal α4ß7+ CD4 T cells relative to control mice who developed mild hepatic steatosis. The increase in α4ß7+ CD4 T cells was associated with markedly higher expression of the α4ß7 ligand mucosal addressin cell adhesion molecule 1 (MAdCAM-1) in the colonic mucosa and livers of WD-fed knockout mice. Elevated MAdCAM-1 expression correlated with increased mucosa-associated Proteobacteria in the WD-fed knockout mice. Antibiotics reduced MAdCAM-1 expression indicating that the diet-altered microbiota promoted colonic and hepatic MAdCAM-1 expression. α4ß7 blockade in WD-fed knockout mice significantly decreased α4ß7+ CD4 T cell recruitment to the intestine and liver, attenuated hepatic inflammation and fibrosis, and improved metabolic indices. MAdCAM-1 blockade also reduced hepatic inflammation and fibrosis in WD-fed knockout mice. Hepatic MAdCAM-1 expression was elevated in patients with NASH and correlated with higher expression of α4 and ß7 integrins. CONCLUSIONS: These findings establish α4ß7/MAdCAM-1 as a critical axis regulating NASH development through colonic and hepatic CD4 T cell recruitment. LAY SUMMARY: Non-alcoholic steatohepatitis (NASH) is an advanced and progressive form of non-alcoholic fatty liver disease (NAFLD), and despite its growing incidence no therapies currently exist to halt NAFLD progression. Herein, we show that blocking integrin receptor α4ß7-mediated recruitment of CD4 T cells to the intestine and liver not only attenuates hepatic inflammation and fibrosis, but also improves metabolic derangements associated with NASH. These findings provide evidence for the potential therapeutic application of α4ß7 antibody in the treatment of human NASH.

CD44 Can Compensate for IgSF11 Deficiency by Associating with the Scaffold Protein PSD-95 during Osteoclast Differentiation.

Differentiation of osteoclasts, which are specialized multinucleated macrophages capable of bone resorption, is driven primarily by receptor activator of NF-κB ligand (RANKL). Additional signaling from cell surface receptors, such as cell adhesion molecules (CAMs), is also required for osteoclast maturation. Previously, we have demonstrated that immunoglobulin superfamily 11 (IgSF11), a member of the immunoglobulin-CAM (IgCAM) family, plays an important role in osteoclast differentiation through association with the scaffold protein postsynaptic density protein 95 (PSD-95). Here, we demonstrate that the osteoclast-expressed CAM CD44 can compensate for IgSF11 deficiency when cell-cell interaction conditions are suboptimal by associating with PSD-95. Impaired osteoclast differentiation in IgSF11-deficient (IgSF11-/-) cultures was rescued by antibody-mediated stimulation of CD44 or by treatment with low-molecular-weight hyaluronan (LMW-HA), a CD44 ligand. Biochemical analysis revealed that PSD-95, which is required for osteoclast differentiation, associates with CD44 in osteoclasts regardless of the presence or absence of IgSF11. RNAi-mediated knockdown of PSD-95 abrogated the effects of either CD44 stimulation or LMW-HA treatment on osteoclast differentiation, suggesting that CD44, similar to IgSF11, is functionally associated with PSD-95 during osteoclast differentiation. Taken together, these results reveal that CD44 can compensate for IgSF11 deficiency in osteoclasts through association with PSD-95.

Western diet-induced increase in colonic bile acids compromises epithelial barrier in nonalcoholic steatohepatitis.

There is compelling evidence implicating intestinal permeability in the pathogenesis of nonalcoholic steatohepatitis (NASH), but the underlying mechanisms remain poorly understood. Here we examined the role of bile acids (BA) in western diet (WD)-induced loss of colonic epithelial barrier (CEB) function in mice with a genetic impairment in intestinal epithelial barrier function, junctional adhesion molecule A knockout mice, F11r-/- . WD-fed knockout mice developed severe NASH, which was associated with increased BA concentration in the cecum and loss of CEB function. Analysis of cecal BA composition revealed selective increases in primary unconjugated BAs in the WD-fed mice, which correlated with increased abundance of microbial taxa linked to BA metabolism. In vitro permeability assays revealed that chenodeoxycholic acid (CDCA), which was elevated in the cecum of WD-fed mice, increased paracellular permeability, while the BA-binding resin sevelamer hydrochloride protected against CDCA-induced loss of barrier function. Sequestration of intestinal BAs by in vivo delivery of sevelamer to WD-fed knockout mice attenuated colonic mucosal inflammation and improved CEB. Sevelamer also reduced hepatic inflammation and fibrosis, and improved metabolic derangements associated with NASH. Collectively, these findings highlight a hitherto unappreciated role for BAs in WD-induced impairment of the intestinal epithelial barrier in NASH.

CRISPLD1: a novel conserved target in the transition to human heart failure.

Heart failure is a major health problem worldwide with a significant morbidity and mortality rate. Although studied extensively in animal models, data from patients at the compensated disease stage are lacking. We sampled myocardium biopsies from aortic stenosis patients with compensated hypertrophy and moderate heart failure and used transcriptomics to study the transition to failure. Sequencing and comparative analysis of analogous samples of mice with transverse aortic constriction identified 25 candidate genes with similar regulation in response to pressure overload, reflecting highly conserved molecular processes. The gene cysteine-rich secretory protein LCCL domain containing 1 (CRISPLD1) is upregulated in the transition to failure in human and mouse and its function is unknown. Homology to ion channel regulatory toxins suggests a role in Ca2+ cycling. CRISPR/Cas9-mediated loss-of-function leads to dysregulated Ca2+ handling in human-induced pluripotent stem cell-derived cardiomyocytes. The downregulation of prohypertrophic, proapoptotic and Ca2+-signaling pathways upon CRISPLD1-KO and its upregulation in the transition to failure implicates a contribution to adverse remodeling. These findings provide new pathophysiological data on Ca2+ regulation in the transition to failure and novel candidate genes with promising potential for therapeutic interventions.

Periostin Promotes Colorectal Tumorigenesis through Integrin-FAK-Src Pathway-Mediated YAP/TAZ Activation.

Periostin is a multifunctional extracellular matrix protein involved in various inflammatory diseases and tumor metastasis; however, evidence regarding whether and how periostin actively contributes to inflammation-associated tumorigenesis remains elusive. Here, we demonstrate that periostin deficiency significantly inhibits the occurrence of colorectal cancer in azoxymethane/dextran sulfate sodium-treated mice and in ApcMin/+ mice. Moreover, periostin deficiency attenuates the severity of colitis and reduces the proliferation of tumor cells. Mechanistically, stromal fibroblast-derived periostin activates FAK-Src kinases through integrin-mediated outside-in signaling, which results in the activation of YAP/TAZ and, subsequently, IL-6 expression in tumor cells. Conversely, IL-6 induces periostin expression in fibroblasts by activating STAT3, which ultimately facilitates colorectal tumor development. These findings provide the evidence that periostin promotes colorectal tumorigenesis, and identify periostin- and IL-6-mediated tumor-stroma interaction as a promising target for treating colitis-associated colorectal cancer.

Close Homolog of L1 Regulates Dendritic Spine Density in the Mouse Cerebral Cortex Through Semaphorin 3B.

Dendritic spines in the developing mammalian neocortex are initially overproduced and then eliminated during adolescence to achieve appropriate levels of excitation in mature networks. We show here that the L1 family cell adhesion molecule Close Homolog of L1 (CHL1) and secreted repellent ligand Semaphorin 3B (Sema3B) function together to induce dendritic spine pruning in developing cortical pyramidal neurons. Loss of CHL1 in null mutant mice in both genders resulted in increased spine density and a greater proportion of immature spines on apical dendrites in the prefrontal and visual cortex. Electron microscopy showed that excitatory spine synapses with postsynaptic densities were increased in the CHL1-null cortex, and electrophysiological recording in prefrontal slices from mutant mice revealed deficiencies in excitatory synaptic transmission. Mechanistically, Sema3B protein induced elimination of spines on apical dendrites of cortical neurons cultured from wild-type but not CHL1-null embryos. Sema3B was secreted by the cortical neuron cultures, and its levels increased when cells were treated with the GABA antagonist gabazine. In vivo CHL1 was coexpressed with Sema3B in pyramidal neuron subpopulations and formed a complex with Sema3B receptor subunits Neuropilin-2 and PlexinA4. CHL1 and NrCAM, a closely related L1 adhesion molecule, localized primarily to distinct spines and promoted spine elimination to Sema3B or Sema3F, respectively. These results support a new concept in which selective spine elimination is achieved through different secreted semaphorins and L1 family adhesion molecules to sculpt functional neural circuits during postnatal maturation.SIGNIFICANCE STATEMENT Dendritic spines in the mammalian neocortex are initially overproduced and then pruned in adolescent life through unclear mechanisms to sculpt maturing cortical circuits. Here, we show that spine and excitatory synapse density of pyramidal neurons in the developing neocortex is regulated by the L1 adhesion molecule, Close Homolog of L1 (CHL1). CHL1 mediated spine pruning in response to the secreted repellent ligand Semaphorin 3B and associated with receptor subunits Neuropilin-2 and PlexinA4. CHL1 and related L1 adhesion molecule NrCAM localized to distinct spines, and promoted spine elimination to Semaphorin 3B and -3F, respectively. These results support a new concept in which selective elimination of individual spines and nascent synapses can be achieved through the action of distinct secreted semaphorins and L1 adhesion molecules.

The role of vasodilator-stimulated phosphoprotein (VASP) in the control of hepatic gluconeogenic gene expression.

During periods in which glucose absorption from the gastrointestinal (GI) tract is insufficient to meet body requirements, hepatic gluconeogenesis plays a key role to maintain normal blood glucose levels. The current studies investigated the role in this process played by vasodilatory-associated phosphoprotein (VASP), a protein that is phosphorylated in hepatocytes by cAMP/protein kinase A (PKA), a key mediator of the action of glucagon. We report that following stimulation of hepatocytes with 8Br-cAMP, phosphorylation of VASP preceded induction of genes encoding key gluconeogenic enzymes, glucose-6-phosphatase (G6p) and phosphoenolpyruvate carboxykinase (Pck1), and that VASP overexpression enhanced this gene induction. Conversely, hepatocytes from mice lacking VASP (Vasp-/-) displayed blunted induction of gluconeogenic enzymes in response to cAMP, and Vasp-/- mice exhibited both greater fasting hypoglycemia and blunted hepatic gluconeogenic enzyme gene expression in response to fasting in vivo. These effects of VASP deficiency were associated with reduced phosphorylation of both CREB (a key transcription factor for gluconeogenesis that lies downstream of PKA) and histone deacetylase 4 (HDAC4), a combination of effects that inhibit transcription of gluconeogenic genes. These data support a model in which VASP functions as a molecular bridge linking the two key signal transduction pathways governing hepatic gluconeogenic gene expression.