Synaptic Wnt/GSK3ß Signaling Hub in Autism.

Hundreds of genes have been associated with autism spectrum disorders (ASDs) and the interaction of weak and de novo variants derive from distinct autistic phenotypes thus making up the "spectrum." The convergence of these variants in networks of genes associated with synaptic function warrants the study of cell signaling pathways involved in the regulation of the synapse. The Wnt/ß-catenin signaling pathway plays a central role in the development and regulation of the central nervous system and several genes belonging to the cascade have been genetically associated with ASDs. In the present paper, we review basic information regarding the role of Wnt/ß-catenin signaling in excitatory/inhibitory balance (E/I balance) through the regulation of pre- and postsynaptic compartments. Furthermore, we integrate information supporting the role of the glycogen synthase kinase 3ß (GSK3ß) in the onset/development of ASDs through direct modulation of Wnt/ß-catenin signaling. Finally, given GSK3ß activity as key modulator of synaptic plasticity, we explore the potential of this kinase as a therapeutic target for ASD.

Early Transcriptional Changes Induced by Wnt/ß-Catenin Signaling in Hippocampal Neurons.

Wnt/ß-catenin signaling modulates brain development and function and its deregulation underlies pathological changes occurring in neurodegenerative and neurodevelopmental disorders. Since one of the main effects of Wnt/ß-catenin signaling is the modulation of target genes, in the present work we examined global transcriptional changes induced by short-term Wnt3a treatment (4 h) in primary cultures of rat hippocampal neurons. RNAseq experiments allowed the identification of 170 differentially expressed genes, including known Wnt/ß-catenin target genes such as Notum, Axin2, and Lef1, as well as novel potential candidates Fam84a, Stk32a, and Itga9. Main biological processes enriched with differentially expressed genes included neural precursor (GO:0061364, p-adjusted = 2.5 × 10-7), forebrain development (GO:0030900, p-adjusted = 7.3 × 10-7), and stem cell differentiation (GO:0048863 p-adjusted = 7.3 × 10-7). Likewise, following activation of the signaling cascade, the expression of a significant number of genes with transcription factor activity (GO:0043565, p-adjusted = 4.1 × 10-6) was induced. We also studied molecular networks enriched upon Wnt3a activation and detected three highly significant expression modules involved in glycerolipid metabolic process (GO:0046486, p-adjusted = 4.5 × 10-19), learning or memory (GO:0007611, p-adjusted = 4.0 × 10-5), and neurotransmitter secretion (GO:0007269, p-adjusted = 5.3 × 10-12). Our results indicate that Wnt/ß-catenin mediated transcription controls multiple biological processes related to neuronal structure and activity that are affected in synaptic dysfunction disorders.

The Reelin receptor ApoER2 is a cargo for the adaptor protein complex AP-4: Implications for Hereditary Spastic Paraplegia.

Adaptor protein complex 4 (AP-4) is a heterotetrameric complex that promotes export of selected cargo proteins from the trans-Golgi network. Mutations in each of the AP-4 subunits cause a complicated form of Hereditary Spastic Paraplegia (HSP). Herein, we report that ApoER2, a receptor in the Reelin signaling pathway, is a cargo of the AP-4 complex. We identify the motif ISSF/Y within the ApoER2 cytosolic domain as necessary for interaction with the canonical signal-binding pocket of the µ4 (AP4M1) subunit of AP-4. AP4E1- knock-out (KO) HeLa cells and hippocampal neurons from Ap4e1-KO mice display increased co-localization of ApoER2 with Golgi markers. Furthermore, hippocampal neurons from Ap4e1-KO mice and AP4M1-KO human iPSC-derived cortical i3Neurons exhibit reduced ApoER2 protein expression. Analyses of biosynthetic transport of ApoER2 reveal differential post-Golgi trafficking of the receptor, with lower axonal distribution in KO compared to wild-type neurons, indicating a role of AP-4 and the ISSF/Y motif in the axonal localization of ApoER2. Finally, analyses of Reelin signaling in mouse hippocampal and human cortical KO neurons show that AP4 deficiency causes no changes in Reelin-dependent activation of the AKT pathway and only mild changes in Reelin-induced dendritic arborization, but reduces Reelin-induced ERK phosphorylation, CREB activation, and Golgi deployment. This work thus establishes ApoER2 as a novel cargo of the AP-4 complex, suggesting that defects in the trafficking of this receptor and in the Reelin signaling pathway could contribute to the pathogenesis of HSP caused by mutations in AP-4 subunits.

The Reelin Receptor ApoER2 is a Cargo for the Adaptor Protein Complex AP-4: Implications for Hereditary Spastic Paraplegia.

Adaptor protein complex 4 (AP-4) is a heterotetrameric complex that promotes protein export from the trans -Golgi network. Mutations in each of the AP-4 subunits cause a complicated form of Hereditary Spastic Paraplegia (HSP). Herein, we report that ApoER2, a receptor in the Reelin signaling pathway, is a cargo of the AP-4 complex. We identify the motif ISSF/Y within the ApoER2 cytosolic domain as necessary for interaction with the canonical signal-binding pocket of the µ4 (AP4M1) subunit of AP-4. AP4E1 -knock-out (KO) HeLa cells and hippocampal neurons from Ap4e1 -KO mice display increased Golgi localization of ApoER2. Furthermore, hippocampal neurons from Ap4e1 -KO mice and AP4M1 -KO human iPSC-derived cortical i3Neurons exhibit reduced ApoER2 protein expression. Analyses of biosynthetic transport of ApoER2 reveal differential post-Golgi trafficking of the receptor, with lower axonal distribution in KO compared to wild-type neurons, indicating a role of AP-4 and the ISSF/Y motif in the axonal localization of ApoER2. Finally, analyses of Reelin signaling in mouse hippocampal and human cortical KO neurons show that AP4 deficiency causes no changes in Reelin-dependent activation of the AKT pathway and only mild changes in Reelin-induced dendritic arborization, but reduces Reelin-induced ERK phosphorylation, CREB activation, and Golgi deployment. Altogether, this work establishes ApoER2 as a novel cargo of the AP-4 complex, suggesting that defects in the trafficking of this receptor and in the Reelin signaling pathway could contribute to the pathogenesis of HSP caused by mutations in AP-4 subunits.

[Results of pancreaticoduodenectomy in the treatment of periampullary tumors]. / Resultados actuales de la pancreatoduodenectomía para el tratamiento de los tumores periampulares y análisis de factores pronósticos de sobrevida.

BACKGROUND: The diagnosis and treatment of periampullary tumors represents a challenge for current medicine. AIM: To review the results of pancreaticoduodenectomy (PDD) in the treatment of periampullary tumors and to identify risk factors that impact the long-term survival. PATIENTS AND METHODS: We performed a retrospective study of patients who underwent a PDD for periampullary tumors between 1993 and 2009. We reviewed perioperative results and long term survival. We performed a multivariate analysis for long-term survival. RESULTS: A PDD was performed in 181 patients aged 58 ± 12 years (98 females). Pyloric preservation was done in 53% and a pancreatogastric anastomosis was used in 94% of cases. Morbidity was 62% and postoperative mortality was 5.5%. Pancreatic cancer was the most frequent pathological finding in 41%, followed by ampullary cancer in 28% and distal bile duct cancer in 16%. Median survival was 17 months, with a five years survival of 24%. Survival for ampullary tumors was 28 months with a five years survival of 32%. The median and five years survival were 14 months and 16% for bile duct cancer and 11 months and 14% for pancreatic cancer. Multivariate analysis identified tumor type (pancreas /bile duct) and lymph node dissemination as independent predictors of mortality. CONCLUSIONS: One quarter of patients experienced long term survival. Mortality predictors were tumor type and lymph node dissemination.

Wnt/ß-Catenin-Dependent Transcription in Autism Spectrum Disorders.

Autism spectrum disorders (ASD) is a heterogeneous group of neurodevelopmental disorders characterized by synaptic dysfunction and defects in dendritic spine morphology. In the past decade, an extensive list of genes associated with ASD has been identified by genome-wide sequencing initiatives. Several of these genes functionally converge in the regulation of the Wnt/ß-catenin signaling pathway, a conserved cascade essential for stem cell pluripotency and cell fate decisions during development. Here, we review current information regarding the transcriptional program of Wnt/ß-catenin signaling in ASD. First, we discuss that Wnt/ß-catenin gain and loss of function studies recapitulate brain developmental abnormalities associated with ASD. Second, transcriptomic approaches using patient-derived induced pluripotent stem cells (iPSC) cells, featuring mutations in high confidence ASD genes, reveal a significant dysregulation in the expression of Wnt signaling components. Finally, we focus on the activity of chromatin-remodeling proteins and transcription factors considered high confidence ASD genes, including CHD8, ARID1B, ADNP, and TBR1, that regulate Wnt/ß-catenin-dependent transcriptional activity in multiple cell types, including pyramidal neurons, interneurons and oligodendrocytes, cells which are becoming increasingly relevant in the study of ASD. We conclude that the level of Wnt/ß-catenin signaling activation could explain the high phenotypical heterogeneity of ASD and be instrumental in the development of new diagnostics tools and therapies.

Golgi Complex Dynamics and Its Implication in Prevalent Neurological Disorders.

Coupling of protein synthesis with protein delivery to distinct subcellular domains is essential for maintaining cellular homeostasis, and defects thereof have consistently been shown to be associated with several diseases. This function is particularly challenging for neurons given their polarized nature and differential protein requirements in synaptic boutons, dendrites, axons, and soma. Long-range trafficking is greatly enhanced in neurons by discrete mini-organelles resembling the Golgi complex (GC) referred to as Golgi outposts (GOPs) which play an essential role in the development of dendritic arborization. In this context, the morphology of the GC is highly plastic, and the polarized distribution of this organelle is necessary for neuronal migration and polarized growth. Furthermore, synaptic components are readily trafficked and modified at GOP suggesting a function for this organelle in synaptic plasticity. However, little is known about GOPs properties and biogenesis and the role of GOP dysregulation in pathology. In this review, we discuss current literature supporting a role for GC dynamics in prevalent neurological disorders such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and epilepsy, and examine the association of these disorders with the wide-ranging effects of GC function on common cellular pathways regulating neuronal excitability, polarity, migration, and organellar stress. First, we discuss the role of Golgins and Golgi-associated proteins in the regulation of GC morphology and dynamics. Then, we consider abnormal GC arrangements observed in neurological disorders and associations with common neuronal defects therein. Finally, we consider the cell signaling pathways involved in the modulation of GC dynamics and argue for a master regulatory role for Reelin signaling, a well-known regulator of neuronal polarity and migration. Determining the cellular pathways involved in shaping the Golgi network will have a direct and profound impact on our current understanding of neurodevelopment and neuropathology and aid the development of novel therapeutic strategies for improved patient care and prognosis.

Positive cystic duct margin at index cholecystectomy in incidental gallbladder cancer is an important negative prognosticator.

BACKGROUND: Prognostic factors following index-cholecystectomy in patients with incidental gallbladder cancer (IGBC) are poorly understood. The aim of this study was to assess the value of the initial cystic duct margin status as a prognosticator factor and to aid in clinical decision making to move forward with curative intent oncologic extended resection (OER). METHODS: This retrospective study included patients with IGBC who underwent subsequent OER with curative intent at 2 centers (USA and Chile) between 1999 and 2016., Patients with and without evidence of residual cancer (RC) at OER were included. Pathologic features were examined, and predictors of overall survival (OS) were analyzed. RESULTS: The study included 179 patients. Thirty-three patients (17%) had a positive cystic duct margin at the index cholecystectomy. Forty-two patients (23%) underwent resection of the common bile duct. OS was significantly worse in the patients with a positive cystic duct margin at index cholecystectomy (OS rates at 5 years, 34% vs 57%; p = 0.032). Following multivariate analysis, only a positive cystic duct margin at index cholecystectomy was predictive of worse OS in patients with no evidence of residual cancer (RC) at OER (hazard ratio, 1.7 95%CI 1.04-2.78; p = 0.034). CONCLUSIONS: A positive cystic duct margin at index-cholecystectomy is a strong independent predictor of worse OS even if no further cancer is found at OER. In patients with positive cystic duct margin and no RC at OER common bile duct resection leads to improved outcomes.

Wnt/ß-catenin signaling stimulates the expression and synaptic clustering of the autism-associated Neuroligin 3 gene.

Synaptic abnormalities have been described in individuals with autism spectrum disorders (ASD). The cell-adhesion molecule Neuroligin-3 (Nlgn3) has an essential role in the function and maturation of synapses and NLGN3 ASD-associated mutations disrupt hippocampal and cortical function. Here we show that Wnt/ß-catenin signaling increases Nlgn3 mRNA and protein levels in HT22 mouse hippocampal cells and primary cultures of rat hippocampal neurons. We characterized the activity of mouse and rat Nlgn3 promoter constructs containing conserved putative T-cell factor/lymphoid enhancing factor (TCF/LEF)-binding elements (TBE) and found that their activity is significantly augmented in Wnt/ß-catenin cell reporter assays. Chromatin immunoprecipitation (ChIP) assays and site-directed mutagenesis experiments revealed that endogenous ß-catenin binds to novel TBE consensus sequences in the Nlgn3 promoter. Moreover, activation of the signaling cascade increased Nlgn3 clustering and co- localization with the scaffold PSD-95 protein in dendritic processes of primary neurons. Our results directly link Wnt/ß-catenin signaling to the transcription of the Nlgn3 gene and support a functional role for the signaling pathway in the dysregulation of excitatory/inhibitory neuronal activity, as is observed in animal models of ASD.

Total esophagogastrectomy plus extended lymphadenectomy with transverse colon interposition: A treatment for extensive esophagogastric junction cancer.

AIM: To review the post-operative morbidity and mortality of total esophagogastrectomy (TEG) with second barrier lymphadenectomy (D2) with interposition of a transverse colon and to determine the oncological outcomes of TEG D2 with interposition of a transverse colon. METHODS: This study consisted of a retrospective review of patients with a cancer diagnosis who underwent TEG between 1997 and 2013. Demographic data, surgery protocols, complications according to Clavien-Dindo classifications, final pathological reports, oncological follow-ups and causes of death were recorded. We used the TNM 2010 and Japanese classifications for nodal dissection of gastric cancer. We used descriptive statistical analysis and Kaplan-Meier survival curves. A P-value of less than 0.05 was considered statistically significant. RESULTS: The series consisted of 21 patients (80.9% men). The median age was 60 years. The 2 main surgical indications were extensive esophagogastric junction cancers (85.7%) and double cancers (14.2%). The mean total surgery time was 405 min (352-465 min). Interposition of a transverse colon through the posterior mediastinum was used for replacement in all cases. Splenectomy was required in 13 patients (61.9%), distal pancreatectomy was required in 2 patients (9.5%) and resection of the left adrenal gland was required in 1 patient (4.7%). No residual cancer surgery was achieved in 75.1% of patients. A total of 71.4% of patients had a postoperative complication. Respiratory complications were the most frequently observed complication. Postoperative mortality was 5.8%. Median follow-up was 13.4 mo. Surgery specific survival at 5 years of follow-up was 32.8%; for patients with curative surgery, it was 39.5% at 5 years. CONCLUSION: TEG for cancer with interposition of a transverse colon is a very complex surgery, and it presents high post-operative morbidity and adequate oncological outcomes.

Resultados actuales de la pancreatoduodenectomía para el tratamiento de los tumores periampulares y análisis de factores pronósticos de sobrevida / Results of pancreaticoduodenectomy in the treatment of periampullary tumors

Background: The diagnosis and treatment of periampullary tumors represents a challenge for current medicine. Aim: To review the results of pancreaticoduodenectomy (PDD) in the treatment of periampullary tumors and to identify risk factors that impact the long-term survival. Patients and Methods: We performed a retrospective study of patients who underwent a PDD for periampullary tumors between 1993 and 2009. We reviewed perioperative results and long term survival. We performed a multivariate analysis for long-term survival. Results: A PDD was performed in 181 patients aged 58 ± 12 years (98 females). Piloric preservation was done in 53 percent and a pancreatogastric anastomosis was used in 94 percent of cases. Morbidity was 62 percent and postoperative mortality was 5.5 percent. Pancreatic cancer was the most frequent pathological finding in 41 percent, followed by ampullary cancer in 28 percent and distal bile duct cancer in 16 percent. Median survival was 17 months, with a five years survival of 24 percent. Survival for ampullary tumors was 28 months with a five years survival of 32 percent. The median and five years survival were 14 months and 16 percent for bile duct cancer and 11 months and 14 percent for pancreatic cancer. Multivariate analysis identified tumor type (pancreas /bile duct) and lymph node dissemination as independent predictors of mortality. Conclusions: One quarter of patients experienced long term survival. Mortality predictors were tumor type and lymph node dissemination.