[Understanding New Regulatory Mechanism of TCR Signal Transduction].

Signal-transducing adaptor protein-2 (STAP-2) is a unique scaffold protein that regulates several immunological signaling pathways, including LIF/LIF receptor and LPS/TLR4 signals. STAP-2 is required for Fas/FasL-dependent T cell apoptosis and SDF-1α-induced T cell migration. Conversely, STAP-2 modulates integrin-mediated T cell adhesion, suggesting that STAP-2 is essential for several negative and positive T cell functions. However, whether STAP-2 is involved in T cell-antigen receptor (TCR)-mediated T cell activation is unknown. STAP-2 deficiency was recently reported to suppress TCR-mediated T cell activation by inhibiting LCK-mediated CD3ζ and ZAP-70 activation. Using STAP-2 deficient mice, it was demonstrated that STAP-2 is required for the pathogenesis of Propionibacterium acnes-induced granuloma formation and experimental autoimmune encephalomyelitis. Here, detailed functions of STAP-2 in TCR-mediated T cell activation, and how STAP-2 affects the pathogenesis of T cell-mediated inflammation and immune diseases, are reviewed.

Dll4 Inhibition Promotes Graft Retention in Fat Grafting Enriched with Adipose-Derived Stem Cells.

Autologous fat grafting is among the safest and most effective treatments for soft-tissue restoration and augmentation, and many efforts have been made to improve its efficiency, including adipose-derived stem cell (ASC) supplementation. Here, we investigated the role of Notch ligand Delta-like ligand 4 (Dll4) in angiogenesis within grafted fat and its effect on graft retention, as well as the effect of Dll4 inhibition on ASC supplementation. Using a murine fat graft model, we investigated the expression of Dll4 in fat grafts and assessed the graft volume, vascularity, and perfusion within the graft, and ASC differentiation patterns depending on the blockade of Dll4. The underlying mechanism of Dll4 inhibition on ASC supplemented fat grafts was investigated using transcriptome analysis. Dll4 was highly expressed in vascular endothelial cells (ECs) within grafted fat, where Dll4-blocking antibody treatment-induced angiogenesis, promoting fat graft retention. In addition, its effect on fat graft retention was synergistically improved when ASCs were concomitantly supplemented. The expression of junctional proteins was increased in ECs, and inflammatory processes were downregulated in grafted fat upon ASC supplementation and Dll4 inhibition. Dll4 inhibition induced vascularization within the grafted fat, thereby promoting graft retention and exhibiting synergistic effects with concomitant ASC supplementation. This study serves as a basis for developing new potential therapeutic approaches targeting Dll4 to improve graft retention after cell-assisted transfer.

PSTPIP1-LYP phosphatase interaction: structural basis and implications for autoinflammatory disorders.

Mutations in the adaptor protein PSTPIP1 cause a spectrum of autoinflammatory diseases, including PAPA and PAMI; however, the mechanism underlying these diseases remains unknown. Most of these mutations lie in PSTPIP1 F-BAR domain, which binds to LYP, a protein tyrosine phosphatase associated with arthritis and lupus. To shed light on the mechanism by which these mutations generate autoinflammatory disorders, we solved the structure of the F-BAR domain of PSTPIP1 alone and bound to the C-terminal homology segment of LYP, revealing a novel mechanism of recognition of Pro-rich motifs by proteins in which a single LYP molecule binds to the PSTPIP1 F-BAR dimer. The residues R228, D246, E250, and E257 of PSTPIP1 that are mutated in immunological diseases directly interact with LYP. These findings link the disruption of the PSTPIP1/LYP interaction to these diseases, and support a critical role for LYP phosphatase in their pathogenesis.

Functions of CNKSR2 and Its Association with Neurodevelopmental Disorders.

The Connector Enhancer of Kinase Suppressor of Ras-2 (CNKSR2), also known as CNK2 or MAGUIN, is a scaffolding molecule that contains functional protein binding domains: Sterile Alpha Motif (SAM) domain, Conserved Region in CNK (CRIC) domain, PSD-95/Dlg-A/ZO-1 (PDZ) domain, Pleckstrin Homology (PH) domain, and C-terminal PDZ binding motif. CNKSR2 interacts with different molecules, including RAF1, ARHGAP39, and CYTH2, and regulates the Mitogen-Activated Protein Kinase (MAPK) cascade and small GTPase signaling. CNKSR2 has been reported to control the development of dendrite and dendritic spines in primary neurons. CNKSR2 is encoded by the CNKSR2 gene located in the X chromosome. CNKSR2 is now considered as a causative gene of the Houge type of X-linked syndromic mental retardation (MRXHG), an X-linked Intellectual Disability (XLID) that exhibits delayed development, intellectual disability, early-onset seizures, language delay, attention deficit, and hyperactivity. In this review, we summarized molecular features, neuronal function, and neurodevelopmental disorder-related variations of CNKSR2.

Smad4 mediates Bmf involvement in sheep granulosa cell apoptosis.

Bcl-2-modifying factor (Bmf) functions to mediate follicular atresia and oocyte growth in mice. It has been proven that TGF-ß can induce Bmf expression via the Smad4 pathway in a variety of cells, and then induce cell apoptosis. Based on this, we hypothesized that Smad4 and Bmf may play important roles in the apoptosis of granulosa cells (GCs) in domestic animals. This study used small-tailed Han sheep follicular GCs cultured in vitro as a model system, and overexpression or interference experiments, to explore the biological roles of Bmf and reveal the preliminary regulatory mechanisms between Smad4 and Bmf in the process of GCs' apoptosis. We found that the proliferation rate of sheep GCs was significantly increased after the knockdown of Bmf, whereas overexpressing Bmf increased the apoptosis rate of GCs, results also verified by the expression patterns of PCNA, Bcl-2, and Bax genes. After the Smad4 knockdown, the apoptosis rate of GCs was increased, while the mRNA and protein expression of Bmf was significantly up-regulated. A rescue experiment verified that the Bmf knockdown could alleviate GCs' apoptosis induced by Smad4 knockdown. In conclusion, our study not only elucidated an important role for Bmf in the apoptosis of sheep GCs but also revealed a new regulatory pathway between Smad4 and Bmf in this process.

PACSIN proteins in vivo: Roles in development and physiology.

Protein kinase C and casein kinase substrate in neurons (PACSINs), or syndapins (synaptic dynamin-associated proteins), are a family of proteins involved in the regulation of cell cytoskeleton, intracellular trafficking and signalling. Over the last twenty years, PACSINs have been mostly studied in the in vitro and ex vivo settings, and only in the last decade reports on their function in vivo have emerged. We first summarize the identification, structure and cellular functions of PACSINs, and then focus on the relevance of PACSINs in vivo. During development in various model organisms, PACSINs participate in diverse processes, such as neural crest cell development, gastrulation, laterality development and neuromuscular junction formation. In mouse, PACSIN2 regulates angiogenesis during retinal development and in human, PACSIN2 associates with monosomy and embryonic implantation. In adulthood, PACSIN1 has been extensively studied in the brain and shown to regulate neuromorphogenesis, receptor trafficking and synaptic plasticity. Several genetic studies suggest a role for PACSIN1 in the development of schizophrenia, which is also supported by the phenotype of mice depleted of PACSIN1. PACSIN2 plays an essential role in the maintenance of intestinal homeostasis and participates in kidney repair processes after injury. PACSIN3 is abundant in muscle tissue and necessary for caveolar biogenesis to create membrane reservoirs, thus controlling muscle function, and has been linked to certain genetic muscular disorders. The above examples illustrate the importance of PACSINs in diverse physiological or tissue repair processes in various organs, and associations to diseases when their functions are disturbed.

The role of ambra1 in Pb-induced developmental neurotoxicity in zebrafish.

Lead is a highly toxic metal that displays developmental neurotoxicity. Ambra1 plays a crucial role in embryonic neural development. At present, the role of Ambra1 in lead-induced developmental neurotoxicity remains unknown. In this study, we investigated the mechanism of Ambra1 concerning its role in lead-induced neurotoxicity. Zebrafish (Danio rerio) embryos were exposed to 0.1, 1, or 10 µM Pb until 5 days post-fertilization, and their locomotor activity was significantly impaired by the 10 µM treatment. Meanwhile, Pb reduced the expression of ambra1a and ambra1b in the brain at 48 and 72 h post-fertilization. Overexpression of ambra1a or ambra1b reversed Pb-induced alterations in locomotor activity, and decreased the apoptotic cell numbers in the brains of Pb-treated zebrafish. Our data reveal a novel protective role of Ambra1 against Pb-induced neural damage in the developing zebrafish.

GAB1 alleviates septic lung injury by inhibiting the TLR4/ NF-κB pathway.

Sepsis, with its high morbidity and mortality, is a difficult problem in critical care medicine. The purpose of this study is to investigate the involvement of GRB2-associated binding protein 1 (GAB1) in septic lung injury. Lipopolysaccharide (LPS)-induced mouse model and A549 cell model were used to simulate septic lung injury. Haematoxylin and eosin (H&E) staining was used to observe the pathological changes. The terminal-deoxynucleotidyl transferase/(TdT)-mediated dUTP-biotin nick end labelling (TUNEL) staining and flow cytometry were used to detect apoptosis. The levels of inflammatory factors in the bronchoalveolar lavage fluid (BALF) were determined by enzyme-linked immunosorbent assay (ELISA). In LPS-induced sepsis mice, GAB1 expression was markedly reduced, and GAB1 overexpression significantly attenuated cell apoptosis and decreased levels of macrophages, neutrophils, and inflammatory factors in the BALF. Our results also demonstrated that GAB1 overexpression significantly reduced LPS-induced apoptosis and inflammation of A549 cells. More importantly, GAB1 overexpression significantly inhibited the Toll-like receptor/ NFkappaB (TLR4/NF-κB) pathway, while silencing GAB1 significantly activated the TLR4/NF-κB pathway and induced apoptosis and increased expression of inflammatory factors. However, the TLR4 inhibitor TAK-242 eliminated the effect of GAB1 silencing on A549. In conclusion, GAB1 is a key regulator of sepsis by inhibiting TLR4/NF-κB mediated apoptosis and inflammation.

Spred1 deficit promotes treatment resistance and transformation of chronic phase CML.

Spred1 is highly expressed in normal hematopoietic stem cells (HSCs). Lack of Spred1 function has been associated with aberrant hematopoiesis and acute leukemias. In chronic myelogenous leukemia (CML), Spred1 is reduced in patients with accelerated phase (AP) or blast crisis (BC) CML, thereby suggesting that deficit of this protein may contribute to disease transformation. In fact, Spred1 knockout (KO) in SCLtTA/BCR-ABL CML mice either globally, or restricted to hematopoietic cells (i.e., HSCs) or to endothelial cells (ECs), led to transformation of chronic phase (CP) CML into AP/BC CML. Upon BCR-ABL induction, all three Spred1 KO CML models showed AP/BC features. However, compared with global Spred1 KO, the AP/BC phenotypes of HSC-Spred1 KO and EC-Spred1 KO CML models were attenuated, suggesting a concurrent contribution of Spred1 deficit in multiple compartments of the leukemic bone marrow niche to the CML transformation. Spred1 KO, regardless if occurred in HSCs or in ECs, increased miR-126 in LSKs (Lin-Sca-1+c-Kit+), a population enriched in leukemic stem cells (LSCs), resulting in expansion of LSCs, likely through hyperactivation of the MAPK/ERK pathway that augmented Bcl-2 expression and stability. This ultimately led to enhancement of Bcl-2-dependent oxidative phosphorylation that supported homeostasis, survival and activity of LSCs and drove AP/BC transformation.

BTBD7 accelerates the epithelial-mesenchymal transition, proliferation and invasion of prostate cancer cells.

PURPOSE: To investigate the potential function of BTBD7 in prostate cancer (PCa) development and the underlying molecular mechanism. METHODS: Serum levels of BTBD7 in PCa patients were examined by qRT-PCR. Regulatory effects of BTBD7 on viability and invasiveness were detected by CCK-8 and Transwell assay, respectively. Moreover, Western blot analysis was conducted to examine protein levels of epithelial-mesenchymal transition (EMT) markers (E-cadherin and N-cadherin) in PCa cells intervened by BTBD7. RESULTS: Serum level of BTBD7 was increased in PCa patients, especially those with Gleason score ≥8 or TNM staging Ⅲ+Ⅳ. Knockdown of BTBD7 attenuated the viability and invasiveness of PCa cells, which upregulated E-cadherin and downregulated N-cadherin. CONCLUSION: Serum level of BTBD7 increases in PCa patients. It accelerates PCa development by triggering proliferative and invasive potentials, as well as EMT.

MicroRNA-139-5p Alleviates High Glucose-Triggered Human Retinal Pigment Epithelial Cell Injury by Targeting LIM-Only Factor 4.

Diabetic retinopathy (DR) is a type of diabetes complication, which can result in loss of vision in adults worldwide. Increasing evidence has revealed that microRNAs (miRs) can regulate DR progression. Thus, the present study was aimed at assessing the possible mechanism of miR-139-5p in high glucose- (HG-) incubated retinal pigment epithelial (ARPE-19) cells. The present results demonstrated that miR-139-5p expression was notably reduced in the serum samples of patients with DR, as well as in ARPE-19 cells treated with HG in a time-dependent manner. Moreover, miR-139-5p was markedly overexpressed by transfection of miR-139-5p mimics into ARPE-19 cells. Overexpression of miR-139-5p markedly induced cell viability and repressed HG-triggered apoptosis. Furthermore, overexpression of miR-139-5p relived HG-enhanced oxidative stress injury. It was found that HG induced malondialdehyde levels but decreased superoxide dismutase and glutathione peroxidase activities in ARPE-19 cells. In addition, overexpression of miR-139-5p could markedly decrease intracellular stress. The results demonstrated that overexpression of miR-139-5p effectively repressed HG-activated inflammation, as indicated by the upregulation of inflammation cytokines, including TNF-α, IL-6, and Cox-2, in ARPE-19 cells. Subsequently, it was identified that LIM-only factor 4 (LMO4) could act as a downstream target for miR-139-5p. LMO4 expression was significantly increased in patients with DR and HG-treated ARPE-19 cells. Mechanistically, knockdown of LMO4 reversed the biological role of miR-139-5p in proliferation, apoptosis, oxidative stress, and release of inflammation factors in vitro. Collectively, these results suggested that miR-139-5p significantly decreased ARPE-19 cell injury caused by HG by inducing proliferation and suppressing cell apoptosis, oxidant stress, and inflammation by modulating LMO4.

Sam68 contributes to intestinal inflammation in experimental and human colitis.

Sam68 is an RNA-binding protein with an adaptor role in signal transduction. Our previous work identified critical proinflammatory and apoptotic functions for Sam68, downstream of the TNF/TNFR1 and TLR2/3/4 pathways. Recent studies have shown elevated Sam68 in inflamed tissues from rheumatoid arthritis and ulcerative colitis (UC) patients, suggesting that Sam68 contributes to chronic inflammatory diseases. Here, we hypothesized that deletion of Sam68 is protective against experimental colitis in vivo, via reductions in TNF-associated inflammatory signaling. We used Sam68 knockout (KO) mice to study the role of Sam68 in experimental colitis, including its contributions to TNF-induced inflammatory gene expression in three-dimensional intestinal organoid cultures. We also studied the expression of Sam68 and inflammatory genes in colon tissues of UC patients. Sam68 KO mice treated with an acute course of DSS exhibited significantly less weight loss and histopathological inflammation compared to wild-type controls, suggesting that Sam68 contributes to experimental colitis. Bone marrow transplants showed no pathologic role for hematopoietic cell-specific Sam68, suggesting that non-hematopoietic Sam68 drives intestinal inflammation. Gene expression analyses showed that Sam68 deficiency reduced the expression of proinflammatory genes in colon tissues from DSS-treated mice, as well as TNF-treated three-dimensional colonic organoids. We also found that inflammatory genes, such as TNF, CCR2, CSF2, IL33 and CXCL10, as well as Sam68 protein, were upregulated in inflamed colon tissues of UC patients. This report identifies Sam68 as an important inflammatory driver in response to intestinal epithelial damage, suggesting that targeting Sam68 may hold promise to treat UC patients.

Ubiquitin Ligases CBL and CBL-B Maintain the Homeostasis and Immune Quiescence of Dendritic Cells.

Dendritic cells (DCs) are composed of multiple lineages of hematopoietic cells and orchestrate immune responses upon detecting the danger and inflammatory signals associated with pathogen and damaged tissues. Under steady-state, DCs are maintained at limited numbers and the functionally quiescent status. While it is known that a fine balance in the DC homeostasis and activation status is also important to prevent autoimmune diseases and hyperinflammation, mechanisms that control DC development and activation under stead-state remain not fully understood. Here we show that DC-specific ablation of CBL and CBL-B (CBL-/-CBL-B-/-) leads to spontaneous liver inflammation and fibrosis and early death of the mice. The mutant mice have a marked expansion of classic CD8α+/CD103+ DCs (cDC1s) in peripheral lymphoid organs and the liver. These DCs exhibit atypical activation phenotypes characterized by an increased production of inflammatory cytokines and chemokines but not the cell surface MHC-II and costimulatory ligands. While the mutant mice also have massive T cell activation, lymphocytes are not required for the disease development. The CBL-/-CBL-B-/- mutation enhances FLT3-mTOR signaling, due to defective FLT3 ubiquitination and degradation. Blockade of FLT3-mTOR signaling normalizes the homeostasis of cDC1s and attenuates liver inflammation. Our result thus reveals a critical role of CBLs in the maintenance of DC homeostasis and immune quiescence. This regulation could be relevant to liver inflammatory diseases and fibrosis in humans.

Avian Metapneumovirus Subgroup C Induces Mitochondrial Antiviral Signaling Protein Degradation through the Ubiquitin-Proteasome Pathway.

The mitochondrial antiviral signaling (MAVS) protein, a critical adapter, links the upstream recognition of viral RNA to downstream antiviral signal transduction. However, the interaction mechanism between avian metapneumovirus subgroup C (aMPV/C) infection and MAVS remains unclear. Here, we confirmed that aMPV/C infection induced a reduction in MAVS expression in Vero cells in a dose-dependent manner, and active aMPV/C replication was required for MAVS decrease. We also found that the reduction in MAVS occurred at the post-translational level rather than at the transcriptional level. Different inhibitors were used to examine the effect of proteasome or autophagy on the regulation of MAVS. Treatment with a proteasome inhibitor MG132 effectively blocked MAVS degradation. Moreover, we demonstrated that MAVS mainly underwent K48-linked ubiquitination in the presence of MG132 in aMPV/C-infected cells, with amino acids 363, 462, and 501 of MAVS being pivotal sites in the formation of polyubiquitin chains. Finally, E3 ubiquitin ligases for MAVS degradation were screened and identified and RNF5 targeting MAVS at Lysine 363 and 462 was shown to involve in MAVS degradation in aMPV/C-infected Vero cells. Overall, these results reveal the molecular mechanism underlying aMPV/C infection-induced MAVS degradation by the ubiquitin-proteasome pathway.

WAC, a novel GBM tumor suppressor, induces GBM cell apoptosis and promotes autophagy.

WAC is closely related to the occurrence and development of tumors. However, its role in human glioblastoma (GBM) and its potential regulatory mechanisms have not been investigated. This study demonstrated that WAC is downregulated in GBM, and its low expression predicts a poor prognosis. We investigated the effect of WAC on the proliferation of glioma cells through a CCK-8 assay, EdU incorporation, and cell formation. The effects of WAC on apoptosis and autophagy in glioma were determined by flow cytometry, TUNEL detection, immunofluorescence, q-PCR, WB, and scanning electron microscopy. We found that overexpression of WAC inhibited the proliferation of glioma cells, promoted apoptosis, and induced autophagy. Therefore, WAC is likely to play a role as a new regulatory molecule in glioma.

Influences of lncRNA HEIH and DKK3 on the clinical features and prognosis of gastric cancer.

PURPOSE: To detect differential expressions of HEIH and DKK3 in gastric cancer (GC) samples, and to elucidate their influences on clinical features and disease prognosis. METHODS: The expression levels of HEIH and DKK3 in GC tissues and adjacent normal ones (>5 cm) were detected by qRT-PCR. Correlation between HEIH and DKK3 levels in GC tissues was analyzed by Pearson's correlation analysis. Sensitivity and specificity of detecting HEIH and DKK3 levels in diagnosing GC were assessed by reactive oxygen species (ROC). 5-year survival in each patient was followed up. Risk factors of prognosis in GC patients were examined by Cox regression model. RESULTS: HEIH was upregulated, and DKK3 was downregulated in GC tissues, displaying a negative correlation. Both HEIH and DKK3 were correlated to tumor diameter, lymph node metastasis and TNM staging. Combined detection of HEIH and DKK3 levels showed high specificity and sensitivity in the diagnosis of GC. Tumor diameter, lymph node metastasis, TNM staging, HEIH and DKK3 levels were independent risk factors for the prognosis of GC. CONCLUSION: The upregulated HEIH and downregulated DKK3 in GC samples showed a negative correlation between each other. HEIH and DKK3 levels were closely linked to tumor diameter, lymph node metastasis and TNM staging in GC patients. These are promising biomarkers for predicting the prognosis of GC.

The Hippo pathway regulates density-dependent proliferation of iPSC-derived cardiac myocytes.

Inducing cardiac myocytes to proliferate is considered a potential therapy to target heart disease, however, modulating cardiac myocyte proliferation has proven to be a technical challenge. The Hippo pathway is a kinase signaling cascade that regulates cell proliferation during the growth of the heart. Inhibition of the Hippo pathway increases the activation of the transcription factors YAP/TAZ, which translocate to the nucleus and upregulate transcription of pro-proliferative genes. The Hippo pathway regulates the proliferation of cancer cells, pluripotent stem cells, and epithelial cells through a cell-cell contact-dependent manner, however, it is unclear if cell density-dependent cell proliferation is a consistent feature in cardiac myocytes. Here, we used cultured human iPSC-derived cardiac myocytes (hiCMs) as a model system to investigate this concept. hiCMs have a comparable transcriptome to the immature cardiac myocytes that proliferate during heart development in vivo. Our data indicate that a dense syncytium of hiCMs can regain cell cycle activity and YAP expression and activity when plated sparsely or when density is reduced through wounding. We found that combining two small molecules, XMU-MP-1 and S1P, increased YAP activity and further enhanced proliferation of low-density hiCMs. Importantly, these compounds had no effect on hiCMs within a dense syncytium. These data add to a growing body of literature that link Hippo pathway regulation with cardiac myocyte proliferation and demonstrate that regulation is restricted to cells with reduced contact inhibition.

A new underlying mechanism for the neuroprotective effect of bosutinib: Reverting toxicity-induced PARylation in SIN1-mediated neurotoxicity.

Increased levels of reactive oxygen and nitrogen species play an important role in the development and progression of neurodegenerative diseases, such as Alzheimer's and Parkinson's disease. The overproduction of these highly reactive chemical species leads to DNA damage and subsequent activation of the poly(ADP-ribose)polymerase (PARP) enzyme. Several studies have demonstrated the potential use of PARP inhibitors for neuroprotection. We previously reported that the dual Src/Abl kinase inhibitor bosutinib (BOS) decreases PARP activity and acts as a chemosensitizer in cancer cells. In this study, we evaluated the neuroprotective potential of BOS with respect to its inhibitory effect on cellular poly(ADP-ribos)ylation (PARylation) using a 3-morpholinosydnonimine (SIN1)-mediated cellular toxicity model. Our data suggest that pretreatment with BOS, especially at lower doses, significantly decreased the level of SIN1-induced cellular PARylation. This regulation pattern of PARylation was found to be associated with the protective effect of BOS against SIN1 on the viability of retinoic acid-differentiated SH-SY5Y cells. Furthermore, while PARP-1 expression was decreased, phosphorylation of SAPK/JNK was not reverted at the observed neuroprotective doses of BOS. In conclusion, we suggest a novel mechanism for the neuroprotective effect of BOS involving the inhibition of cellular PARylation.

The Emerging Role of Sfrp5 and Wnt5a in the Pathogenesis of Obesity: Implications for a Healthy Diet and Lifestyle.

In recent decades, the prevalence of obesity has risen dramatically worldwide among all age groups. Obesity is characterized by excess fat accumulation and chronic low-grade inflammation. The adipose tissue functions as a metabolically active endocrine organ secreting adipokines. A novel duo of adipokines, the anti-inflammatory secreted frizzled-related protein 5 (Sfrp5) and the proinflammatory wingless type mouse mammary tumor virus (MMTV) integration site family member 5A (Wnt5a), signal via the non-canonical Wnt pathway. Recent evidence suggests that Sfpr5 and Wnt5a play a key role in the pathogenesis of obesity and its metabolic complications. This review summarizes the current knowledge on the novel regulatory system of anti-inflammatory Sfrp5 and pro-inflammatory Wnt5a, and their relation to obesity and obesity-related complications. Future studies are required to investigate the potential role of Sfrp5 and Wnt5a as biomarkers for monitoring the response to lifestyle interventions and for predicting the development of cardiometabolic risk factors. These adipokines may also serve as novel therapeutic targets for obesity-related disorders.

The Golgi-Associated PDZ Domain Protein Gopc/PIST Is Required for Synaptic Targeting of mGluR5.

In neuronal cells, many membrane receptors interact via their intracellular, C-terminal tails with PSD-95/discs large/ZO-1 (PDZ) domain proteins. Some PDZ proteins act as scaffold proteins. In addition, there are a few PDZ proteins such as Gopc which bind to receptors during intracellular transport. Gopc is localized at the trans-Golgi network (TGN) and binds to a variety of receptors, many of which are eventually targeted to postsynaptic sites. We have analyzed the role of Gopc by knockdown in primary cultured neurons and by generating a conditional Gopc knockout (KO) mouse line. In neurons, targeting of neuroligin 1 (Nlgn1) and metabotropic glutamate receptor 5 (mGlu5) to the plasma membrane was impaired upon depletion of Gopc, whereas NMDA receptors were not affected. In the hippocampus and cortex of Gopc KO animals, expression levels of Gopc-associated receptors were not altered, while their subcellular localization was disturbed. The targeting of mGlu5 to the postsynaptic density was reduced, coinciding with alterations in mGluR-dependent synaptic plasticity and deficiencies in a contextual fear conditioning paradigm. Our data imply Gopc in the correct subcellular sorting of its associated mGlu5 receptor in vivo.