Efficacy of GV1001 with gemcitabine/capecitabine in previously untreated patients with advanced pancreatic ductal adenocarcinoma having high serum eotaxin levels (KG4/2015): an open-label, randomised, Phase 3 trial.

BACKGROUND: The TeloVac study indicated GV1001 did not improve the survival of advanced pancreatic ductal adenocarcinoma (PDAC). However, the cytokine examinations suggested that high serum eotaxin levels may predict responses to GV1001. This Phase III trial assessed the efficacy of GV1001 with gemcitabine/capecitabine for eotaxin-high patients with untreated advanced PDAC. METHODS: Patients recruited from 16 hospitals received gemcitabine (1000 mg/m2, D 1, 8, and 15)/capecitabine (830 mg/m2 BID for 21 days) per month either with (GV1001 group) or without (control group) GV1001 (0.56 mg; D 1, 3, and 5, once on week 2-4, 6, then monthly thereafter) at random in a 1:1 ratio. The primary endpoint was overall survival (OS) and secondary end points included time to progression (TTP), objective response rate, and safety. RESULTS: Total 148 patients were randomly assigned to the GV1001 (n = 75) and control groups (n = 73). The GV1001 group showed improved median OS (11.3 vs. 7.5 months, P = 0.021) and TTP (7.3 vs. 4.5 months, P = 0.021) compared to the control group. Grade >3 adverse events were reported in 77.3% and 73.1% in the GV1001 and control groups (P = 0.562), respectively. CONCLUSIONS: GV1001 plus gemcitabine/capecitabine improved OS and TTP compared to gemcitabine/capecitabine alone in eotaxin-high patients with advanced PDAC. CLINICAL TRIAL REGISTRATION: NCT02854072.

Dual role of deubiquitinating enzyme USP19 regulates mitotic progression and tumorigenesis by stabilizing survivin.

Survivin is a component of the chromosomal passenger complex, which includes Aurora B, INCENP, and Borealin, and is required for chromosome segregation and cytokinesis. We performed a genome-wide screen of deubiquitinating enzymes for survivin. For the first time, we report that USP19 has a dual role in the modulation of mitosis and tumorigenesis by regulating survivin expression. Our results found that USP19 stabilizes and interacts with survivin in HCT116 cells. USP19 deubiquitinates survivin protein and extends its half-life. We also found that USP19 functions as a mitotic regulator by controlling the downstream signaling of survivin protein. Targeted genome knockout verified that USP19 depletion leads to several mitotic defects, including cytokinesis failure. In addition, USP19 depletion results in significant enrichment of apoptosis and reduces the growth of tumors in the mouse xenograft. We envision that simultaneous targeting of USP19 and survivin in oncologic drug development would increase therapeutic value and minimize redundancy.

Malignant potential of small pancreatic neuroendocrine neoplasm and its risk factors: A multicenter nationwide study.

BACKGROUND: Pancreatic neuroendocrine neoplasms (PNENs) show heterogeneous biological behavior, and most small PNENs show indolent features. Consequently, selected cases can be considered for observation only, according to the National Comprehensive Cancer Network guideline, however, supporting clinical evidence is lacking. We investigated the clinical course of small PNENs and their risk factors for malignant potential. METHODS: A total of 158 patients with small pathologically confirmed PNENs ≤2 cm in initial imaging were retrospectively enrolled from 14 institutions. The primary outcome was any metastasis or recurrence event during follow-up. RESULTS: The median age was 57 years (range, 22-82 years), and 86 patients (54%) were female. The median tumor size at initial diagnosis was 13 mm (range, 7-20 mm). PNENs were pathologically confirmed by surgery in 137 patients and by EUS-guided fine needle aspiration biopsy (EUS-FNAB) in 21 patients. Eight patients underwent EUS-FNAB followed by surgical resection. The results of WHO grade were available in 150 patients, and revealed 123 grade 1, 25 grade 2, and 2 neuroendocrine carcinomas. A total of 145 patients (92%) underwent surgical resection, and three patients had regional lymph node metastasis. During the entire follow-up of median 45.6 months, 11 metastases or recurrences (7%) occurred. WHO grade 2 (HR 13.97, 95% CI 2.60-75.03, p = 0.002) was the only predictive factor for malignant potential in multivariable analysis. CONCLUSIONS: WHO grade is responsible for the malignant potential of small PNENs ≤2 cm. Thus, EUS-FNAB could be recommended in order to provide early treatment strategies of small PNENs.

Somatic Mutations in TSC1 and TSC2 Cause Focal Cortical Dysplasia.

Focal cortical dysplasia (FCD) is a major cause of the sporadic form of intractable focal epilepsies that require surgical treatment. It has recently been reported that brain somatic mutations in MTOR account for 15%-25% of FCD type II (FCDII), characterized by cortical dyslamination and dysmorphic neurons. However, the genetic etiologies of FCDII-affected individuals who lack the MTOR mutation remain unclear. Here, we performed deep hybrid capture and amplicon sequencing (read depth of 100×-20,012×) of five important mTOR pathway genes-PIK3CA, PIK3R2, AKT3, TSC1, and TSC2-by using paired brain and saliva samples from 40 FCDII individuals negative for MTOR mutations. We found that 5 of 40 individuals (12.5%) had brain somatic mutations in TSC1 (c.64C>T [p.Arg22Trp] and c.610C>T [p.Arg204Cys]) and TSC2 (c.4639G>A [p.Val1547Ile]), and these results were reproducible on two different sequencing platforms. All identified mutations induced hyperactivation of the mTOR pathway by disrupting the formation or function of the TSC1-TSC2 complex. Furthermore, in utero CRISPR-Cas9-mediated genome editing of Tsc1 or Tsc2 induced the development of spontaneous behavioral seizures, as well as cytomegalic neurons and cortical dyslamination. These results show that brain somatic mutations in TSC1 and TSC2 cause FCD and that in utero application of the CRISPR-Cas9 system is useful for generating neurodevelopmental disease models of somatic mutations in the brain.

A prospective, randomized, multicenter clinical trial comparing 25-gauge and 20-gauge biopsy needles for endoscopic ultrasound-guided sampling of solid pancreatic lesions.

BACKGROUND: Various core biopsy needles have previously been developed for endoscopic ultrasound-guided fine-needle biopsy (EUS-FNB). However, the properties of needle gauge in the diagnostic outcomes of solid pancreatic lesions remain unknown. This trial compared the procurement rates of histologic cores from solid pancreatic lesions with EUS-FNB using 20- and 25-gauge (G) FNB needles. METHODS: In a prospective randomized multicenter clinical trial, patients with solid pancreatic lesions underwent EUS-FNB with either a 20-gauge or a 25-gauge FNB needle. The rates of histologic core procurement, overall diagnostic accuracy, and adverse events were compared between the two groups (20-gauge or 25-gauge FNB needle). RESULTS: In total, 88 patients (48 men, 40 women, mean age 65.7 years) were enrolled. No significant differences were found in the demographic characteristics between the two groups (20-gauge or 25-gauge FNB needle). The procurement rate of histologic cores in the 20-guage FNB needle group (41/45, 91.1%) was significantly higher than that in the 25-guage FNB needle group (32/43, 74.4%, P = 0.037). However, no significant differences were found in the overall diagnostic accuracy between 20-guage FNB needle (40/45, 88.9%) and 25-guage FNB needle (34/43, 79.1%, P = 0.208). No procedure-related adverse events were observed in either group. CONCLUSIONS: Although both FNB needles provided high overall diagnostic accuracy, the reliability of the 20-guage FNB needle is better than the 25-guage FNB needle when retrieving samples for histological analysis.

Preparation and Characterization of the Sputtered TiAlN Coatings Using a Ti-Al Alloy Metal Target.

Titanium aluminium nitride (TiAlN) ternary coatings were deposited on glass substrates by means of reactive magnetron sputtering technique, using a Ti-Al alloy metal target (Ti0.5Al0.5). The depositions were performed at various N2 and Ar flux ratios of N2/(Ar + N2) ═ 33, 50, 67, 83%. The structure, morphology, chemical composition and mechanical properties were investigated by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), energy dispersive X-ray spectroscopy (EDS), and nano indenter (MTS System), respectively. The orientation of coatings depends on the flux ratios of N2/(Ar + N2) and substrate temperature. The coatings deposited with N2/(Ar + N2) ratios of 33, 50 at.% consists of pyramid-like column grains separated by porous and voids, which can be attributed to cubic-TiN (220) preferred orientation. The coatings deposited with N2/(Ar + N2) greater than 67% exhibits the phase of hexagonal-AlN and cubic-TiN. The surface of coatings becomes more compact and smoother with the N2/(Ar + N2) ratios increase. The coatings deposited with N2/(Ar+N2) ratio of 83% shows the largest hardness of 21.5 GPa, which is attributed to the preferred (200) orientation. However, this hardness increases significantly with increasing substrate temperature. The coatings deposited at more than 100 °C exhibited the (111) and/or (200) orientation. The amounts of grains grown along the (111) and (200) orientations play a significant role on the mechanical performance of TiAlN coatings. Four independent mechanisms, such as TiAlN stoichiometry and lattice parameter, the (111) preferred growth orientation, and the density increases (elimination of void), were found to contribute to the enhancement of TiAlN mechanical performance.

Aggressive intravenous hydration with lactated Ringer's solution for prevention of post-ERCP pancreatitis: a prospective randomized multicenter clinical trial.

BACKGROUND AND STUDY AIMS : The present study aimed to determine the type of intravenous hydration that is best suited to reducing the incidence of post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis. PATIENTS AND METHODS: In a prospective randomized multicenter trial, average-to-high risk patients who underwent first-time ERCP were randomly assigned to three groups (1:1:1) who received: aggressive intravenous hydration (3 mL/kg/h during ERCP, a 20-mL/kg bolus and 3 mL/kg/h for 8 hours after ERCP) with either lactated Ringer's solution (LRS) or normal saline solution (NSS), or standard intravenous hydration with LRS (1.5 mL/kg/h during and for 8 hours after ERCP). The primary end point was post-ERCP pancreatitis (PEP). RESULTS: 395 patients were enrolled, and 385 completed the protocols. The three groups showed no significant differences in demographic characteristics. There was a significant difference in the intention-to-treat (ITT) PEP rate between the aggressive LRS group (3.0 %, 95 % confidence interval [CI] 0.1 % - 5.9 %; 4 /132), the aggressive NSS group (6.7 %, 95 %CI 2.5 % - 10.9 %; 9 /134) and the standard LRS group (11.6 %, 95 %CI 6.1 % - 17.2 %; 15 /129; P = 0.03). In the two-group comparisons, the ITT PEP rate was significantly lower for the aggressive LRS group than for the standard LRS group (relative risk [RR] 0.26, 95 %CI 0.08 - 0.76; P = 0.008). There was no significant difference in the ITT PEP rate between the aggressive NSS group and the standard LRS group (RR 0.57, 95 %CI 0.26 - 1.27; P = 0.17). CONCLUSION: Aggressive hydration with LRS is the best approach to intravenous hydration for the prevention of PEP in average-to-high risk patients.

Lower expression of endogenous intestinal alkaline phosphatase may predict worse prognosis in patients with Crohn's disease.

BACKGROUNDS: Intestinal alkaline phosphatase (IAP) plays important role in gut homeostasis. We aimed to evaluate the expression of endogenous IAP and to assess the clinical course according to the expression of endogenous IAP in patients with Crohn's disease (CD). METHODS: A total of 32 consecutive patients (14 males) with CD were included in the study. We measured the level of endogenous iAP in inflamed and noninflamed colonic mucosa. To verify the inflammation status, we measured the level of mRNA for IL-6, TNF-α, and TLR-4. We monitored the clinical courses of patients during follow-up after acquisition of biopsy specimens. RESULTS: Median age of patients was 22.5 years (range, 15-49). Median CD activity index (CDAI, range) was 93.7 (22.8~ 154.9). There were colonic involvements in all patients and perianal involvement in 43.8% patients. The mRNA levels of IL-6 (p = 0.005) and TLR-4 (p = 0.013) in inflamed mucosa were significantly higher than those in non-inflamed mucosa. However, there was no difference of expression of TNF-α mRNA (p = 0.345). During a 14-month follow-up (range, 9 months-54 months), there were 19 patients with clinical recurrences. There were 9 patients (9/19, 47.4%) with IAP expression ratio (inflamed to non-inflamed) ≤ 1.0 in patients with clinical recurrence while there was one patient (1/13, 7.7%) with IAP ratio ≤ 1.0 in patients without clinical recurrence (p = 0.024). CONCLUSION: Lower expression of IAP in inflamed mucosa compared to non-inflamed mucosa may be associated with clinical recurrence in patients with CD.

Efficient Generation of Dopamine Neurons by Synthetic Transcription Factor mRNAs.

Generation of functional dopamine (DA) neurons is an essential step for the development of effective cell therapy for Parkinson's disease (PD). The generation of DA neurons can be accomplished by overexpression of DA-inducible genes using virus- or DNA-based gene delivery methods. However, these gene delivery methods often cause chromosomal anomalies. In contrast, mRNA-based gene delivery avoids this problem and therefore is considered safe to use in the development of cell-based therapy. Thus, we used mRNA-based gene delivery method to generate safe DA neurons. In this study, we generated transformation-free DA neurons by transfection of mRNA encoding DA-inducible genes Nurr1 and FoxA2. The delivery of mRNA encoding dopaminergic fate inducing genes proved sufficient to induce naive rat forebrain precursor cells to differentiate into neurons exhibiting the biochemical, electrophysiological, and functional properties of DA neurons in vitro. Additionally, the generation efficiency of DA neurons was improved by the addition of small molecules, db-cAMP, and the adjustment of transfection timing. The successful generation of DA neurons using an mRNA-based method offers the possibility of developing clinical-grade cell sources for neuronal cell replacement treatment for PD.

Nuclear receptor Nurr1 agonists enhance its dual functions and improve behavioral deficits in an animal model of Parkinson's disease.

Parkinson's disease (PD), primarily caused by selective degeneration of midbrain dopamine (mDA) neurons, is the most prevalent movement disorder, affecting 1-2% of the global population over the age of 65. Currently available pharmacological treatments are largely symptomatic and lose their efficacy over time with accompanying severe side effects such as dyskinesia. Thus, there is an unmet clinical need to develop mechanism-based and/or disease-modifying treatments. Based on the unique dual role of the nuclear orphan receptor Nurr1 for development and maintenance of mDA neurons and their protection from inflammation-induced death, we hypothesize that Nurr1 can be a molecular target for neuroprotective therapeutic development for PD. Here we show successful identification of Nurr1 agonists sharing an identical chemical scaffold, 4-amino-7-chloroquinoline, suggesting a critical structure-activity relationship. In particular, we found that two antimalarial drugs, amodiaquine and chloroquine stimulate the transcriptional function of Nurr1 through physical interaction with its ligand binding domain (LBD). Remarkably, these compounds were able to enhance the contrasting dual functions of Nurr1 by further increasing transcriptional activation of mDA-specific genes and further enhancing transrepression of neurotoxic proinflammatory gene expression in microglia. Importantly, these compounds significantly improved behavioral deficits in 6-hydroxydopamine lesioned rat model of PD without any detectable signs of dyskinesia-like behavior. These findings offer proof of principle that small molecules targeting the Nurr1 LBD can be used as a mechanism-based and neuroprotective strategy for PD.

Self-expandable metal stents for choledocholithiasis in Billroth II gastrectomy patients.

BACKGROUND: Efficient ampullary intervention is essential for endoscopic retrograde cholangiopancreatography (ERCP) in patients with a prior Billroth II gastrectomy. We retrospectively evaluated the safety and effectiveness of ampullary intervention using fully covered self-expandable metal stents (FCSEMSs) for the management of common bile duct (CBD) stones in a subset of patients with a history of Billroth II gastrectomy. METHODS: This retrospective analysis involved patients with a prior Billroth II gastrectomy who underwent ampullary intervention with FCSEMSs for the management of CBD stones. The factors associated with FCSEMSs placement, treatment success, and procedural complications were analyzed. RESULTS: A group of 15 patients (10 males; median age, 78 years) underwent biliary metal stent placement for high degree of CBD angulation (6), small or flat papilla with unclear margin (5), current use of double antiplatelet agents or an anticoagulant (2), unwanted instrumentation of the cystic duct (1), and insecure position of the scope (1). Ampullary intervention with FCSEMSs was successful in all patients. After dilating the ampulla of Vater and building a durable conduit with FCSEMSs immediately, CBD stones were removed successfully from all patients in a single session. A mild post-ERCP pancreatitis occurred in one patient, who recovered without complications. CONCLUSION: Ampullary intervention with FCSEMSs is safe and effective for the management of CBD stones in a subset of patients with a history of Billroth II gastrectomy.

Restoration of common bile duct diameter within 2 weeks after endoscopic stone retraction is a preventive factor for stone recurrence.

BACKGROUND: Little information is available about the relationship between restoration of common bile duct (CBD) diameter after endoscopic stone retraction and recurrence of CBD stones in elderly patients. The present study was to determine whether restoration of CBD diameter is a preventive factor for CBD stone recurrence in elderly patients who underwent endoscopic retrograde cholangiopancreatography (ERCP). METHODS: From January 2006 to December 2010, 238 patients underwent the first and the second session of ERCP for the removal of CBD stones. Among them, 173 were over 65 years old. These patients were divided into recurrent group and non-recurrent group. Restoration of CBD diameter and patients' characteristics were compared. RESULTS: There was no statistical difference in patients' characteristics, associated diseases, or ERCP-related complications between the two groups. Reduction of CBD diameter was significantly larger in the non-recurrent group (2.7 ±â€¯1.7 mm) compared to that in the recurrent group (1.4 ±â€¯2.3 mm, P = 0.002). The proportion of patients with restoration of CBD diameter were significantly lower in the recurrent group (6/42, 14.3%) compared with that in the non-recurrent group (67/131, 51.1%) (P < 0.01). CONCLUSIONS: There is an inverse relationship between restoration of CBD diameter and CBD stone recurrence. Therefore, patients without restoration of CBD diameter within 2 weeks after endoscopic stone removal should be monitored more frequently.

Regulation of c-Myc Expression by Ahnak Promotes Induced Pluripotent Stem Cell Generation.

We have previously reported that Ahnak-mediated TGFß signaling leads to down-regulation of c-Myc expression. Here, we show that inhibition of Ahnak can promote generation of induced pluripotent stem cells (iPSC) via up-regulation of endogenous c-Myc. Consistent with the c-Myc inhibitory role of Ahnak, mouse embryonic fibroblasts from Ahnak-deficient mouse (Ahnak(-/-) MEF) show an increased level of c-Myc expression compared with wild type MEF. Generation of iPSC with just three of the four Yamanaka factors, Oct4, Sox2, and Klf4 (hereafter 3F), was significantly enhanced in Ahnak(-/-) MEF. Similar results were obtained when Ahnak-specific shRNA was applied to wild type MEF. Of note, expressionof Ahnak was significantly induced during the formation of embryoid bodies from embryonic stem cells, suggesting that Ahnak-mediated c-Myc inhibition is involved in embryoid body formation and the initial differentiation of pluripotent stem cells. The iPSC from 3F-infected Ahnak(-/-) MEF cells (Ahnak(-/-)-iPSC-3F) showed expression of all stem cell markers examined and the capability to form three primary germ layers. Moreover, injection of Ahnak(-/-)-iPSC-3F into athymic nude mice led to development of teratoma containing tissues from all three primary germ layers, indicating that iPSC from Ahnak(-/-) MEF are bona fide pluripotent stem cells. Taken together, these data provide evidence for a new role for Ahnak in cell fate determination during development and suggest that manipulation of Ahnak and the associated signaling pathway may provide a means to regulate iPSC generation.

Foxa2 acts as a co-activator potentiating expression of the Nurr1-induced DA phenotype via epigenetic regulation.

Understanding how dopamine (DA) phenotypes are acquired in midbrain DA (mDA) neuron development is important for bioassays and cell replacement therapy for mDA neuron-associated disorders. Here, we demonstrate a feed-forward mechanism of mDA neuron development involving Nurr1 and Foxa2. Nurr1 acts as a transcription factor for DA phenotype gene expression. However, Nurr1-mediated DA gene expression was inactivated by forming a protein complex with CoREST, and then recruiting histone deacetylase 1 (Hdac1), an enzyme catalyzing histone deacetylation, to DA gene promoters. Co-expression of Nurr1 and Foxa2 was established in mDA neuron precursor cells by a positive cross-regulatory loop. In the presence of Foxa2, the Nurr1-CoREST interaction was diminished (by competitive formation of the Nurr1-Foxa2 activator complex), and CoREST-Hdac1 proteins were less enriched in DA gene promoters. Consequently, histone 3 acetylation (H3Ac), which is responsible for open chromatin structures, was strikingly increased at DA phenotype gene promoters. These data establish the interplay of Nurr1 and Foxa2 as the crucial determinant for DA phenotype acquisition during mDA neuron development.

Promotion of Cortical Neurogenesis from the Neural Stem Cells in the Adult Mouse Subcallosal Zone.

Neurogenesis occurs spontaneously in the subventricular zone (SVZ) of the lateral ventricle in adult rodent brain, but it has long been debated whether there is sufficient adult neurogenesis in human SVZ. Subcallosal zone (SCZ), a posterior continuum of SVZ closely associated with posterior regions of cortical white matter, has also been reported to contain adult neural stem cells (aNSCs) in both rodents and humans. However, little is known whether SCZ-derived aNSC (SCZ-aNSCs) can produce cortical neurons following brain injury. We found that SCZ-aNSCs exhibited limited neuronal differentiation potential in culture and after transplantation in mice. Neuroblasts derived from SCZ initially migrated toward injured cortex regions following brain injury, but later exhibited apoptosis. Overexpression of anti-apoptotic bcl-xL in the SCZ by retroviral infection rescued neuroblasts from cell death in the injured cortex, but neuronal maturation was still limited, resulting in atrophy. In combination with Bcl-xL, infusion of brain-derived neurotropic factor rescued atrophy, and importantly, a subset of such SCZ-aNSCs differentiated and attained morphological and physiological characteristics of mature, excitatory neurons. These results suggest that the combination of anti-apoptotic and neurotrophic factors might enable the use of aNSCs derived from the SCZ in cortical neurogenesis for neural replacement therapy.

Subjective taste to polyethylene glycol is associated with efficacy of right colon preparation.

AIM: A prospective observational trial with preparations using polyethylene glycol (PEG) to compare patient compliance and adverse events according to individual subjective taste. METHODS: A total of 299 outpatients (mean ± standard deviation [SD] 56.5 ± 13.8 years, 172 males) were recruited for our study. We assessed the efficacy of bowel preparation, subjective taste to their regimens, compliance and adverse events during the preparation. RESULTS: We achieved adequate preparation in 267 (89.3%). A total of 124 patients (41.5%) had 'unacceptable taste' to their regimens. The patients with acceptable taste had better compliance than the patients with unacceptable taste (p = .009). The patients with unacceptable taste had more frequent adverse events such as nausea, vomiting and abdominal bloating than the patients with acceptable taste (all p < .001, Table 2). Patients with unacceptable taste (16.1%) had more frequent inadequate preparation in overall colon than patients with acceptable taste (6.9%, p = .011). There was a significant difference in the efficacy of preparation of right colon between the two groups (p = .004). CONCLUSION: Subjective taste to PEG is associated with efficacy of right colon preparation. In addition, subjective taste to PEG is associated with compliance and adverse events.

LIN28A enhances the therapeutic potential of cultured neural stem cells in a Parkinson's disease model.

The original properties of tissue-specific stem cells, regardless of their tissue origins, are inevitably altered during in vitro culturing, lessening the clinical and research utility of stem cell cultures. Specifically, neural stem cells derived from the ventral midbrain lose their dopamine neurogenic potential, ventral midbrain-specific phenotypes, and repair capacity during in vitro cell expansion, all of which are critical concerns in using the cultured neural stem cells in therapeutic approaches for Parkinson's disease. In this study, we observed that the culture-dependent changes of neural stem cells derived from the ventral midbrain coincided with loss of RNA-binding protein LIN28A expression. When LIN28A expression was forced and sustained during neural stem cell expansion using an inducible expression-vector system, loss of dopamine neurogenic potential and midbrain phenotypes after long-term culturing was blocked. Furthermore, dopamine neurons that differentiated from neural stem cells exhibited remarkable survival and resistance against toxic insults. The observed effects were not due to a direct action of LIN28A on the differentiated dopamine neurons, but rather its action on precursor neural stem cells as exogene expression was switched off in the differentiating/differentiated cultures. Remarkable and reproducible behavioural recovery was shown in all Parkinson's disease rats grafted with neural stem cells expanded with LIN28A expression, along with extensive engraftment of dopamine neurons expressing mature neuronal and midbrain-specific markers. These findings suggest that LIN28A expression during stem cell expansion could be used to prepare therapeutically competent donor cells.

Bidirectional Signaling of Neuregulin-2 Mediates Formation of GABAergic Synapses and Maturation of Glutamatergic Synapses in Newborn Granule Cells of Postnatal Hippocampus.

Expression of neuregulin-2 (NRG2) is intense in a few regions of the adult brain where neurogenesis persists; however, little is understood about its role in developments of newborn neurons. To study the role of NRG2 in synaptogenesis at different developmental stages, newborn granule cells in rat hippocampal slice cultures were labeled with retrovirus encoding tetracycline-inducible microRNA targeting NRG2 and treated with doxycycline (Dox) at the fourth or seventh postinfection day (dpi). The developmental increase of GABAergic postsynaptic currents (GPSCs) was suppressed by the early Dox treatment (4 dpi), but not by late treatment (7 dpi). The late Dox treatment was used to study the effect of NRG2 depletion specific to excitatory synaptogenesis. The Dox effect on EPSCs emerged 4 d after the impairment in dendritic outgrowth became evident (10 dpi). Notably, Dox treatment abolished the developmental increases of AMPA-receptor mediated EPSCs and the AMPA/NMDA ratio, indicating impaired maturation of glutamatergic synapses. In contrast to GPSCs, Dox effects on EPSCs and dendritic growth were independent of ErbB4 and rescued by concurrent overexpression of NRG2 intracellular domain. These results suggest that forward signaling of NRG2 mediates GABAergic synaptogenesis and its reverse signaling contributes to dendritic outgrowth and maturation of glutamatergic synapses. SIGNIFICANCE STATEMENT: The hippocampal dentate gyrus is one of special brain regions where neurogenesis persists throughout adulthood. Synaptogenesis is a critical step for newborn neurons to be integrated into preexisting neural network. Because neuregulin-2 (NRG2), a growth factor, is intensely expressed in these regions, we investigated whether it plays a role in synaptogenesis and dendritic growth. We found that NRG2 has dual roles in the development of newborn neurons. For GABAergic synaptogenesis, the extracellular domain of NRG2 acts as a ligand for a receptor on GABAergic neurons. In contrast, its intracellular domain was essential for dendritic outgrowth and glutamatergic synapse maturation. These results imply that NRG2 may play a critical role in network integration of newborn neurons.