Locally Activating TrkB Receptor Generates Actin Waves and Specifies Axonal Fate

Actin waves are filamentous actin (F-actin)-rich structures that initiate in the somato-neuritic area and move toward neurite ends. The upstream cues that initiate actin waves are poorly understood. Here, using an optogenetic approach (Opto-cytTrkB), we found that local activation of the TrkB receptor around the neurite end initiates actin waves and triggers neurite elongation. During actin wave generation, locally activated TrkB signaling in the distal neurite was functionally connected with preferentially localized Rac1 and its signaling pathways in the proximal region. Moreover, TrkB activity changed the location of ankyrinG––the master organizer of the axonal initial segment-and initiated the stimulated neurite to acquire axonal characteristics. Taken together, these findings suggest that local Opto-cytTrkB activation switches the fate from minor to major axonal neurite during neuronal polarization by generating actin waves.C. 2019 Elsevier Ltd.11Nsciescopu

Marriage Intention among Korean Young Adults: Trends and Influencing Factors

The recent increase in the tendency of people to marry late or to opt out of marriage entirely is among the key contributors to Korea’s low fertility rate. One possible cause of this tendency may be a change in how marriage is valued among Korea’s youth. The marriage intentions of young adults can be classified into “positive”, “negative”, and “neutral”. Over time, positive marriage intentions have declined across all age groups (2010: 61% → 2020: 39%; ages 25–29), with no significant change in negative marriage intentions. In contrast, neutral marriage intentions have increased significantly (2010: 36% → 2020: 53%; ages 25–29). This phenomenon may be attributable to the increase in the number of young adults who prioritize survival over thinking about the future. However, neutral marriage values can be changed into positive values at any time. A holistic overview of Korean society is necessary to determine how the values of young adults might be influenced to align with a traditional life process

Noninvasive optical activation of Flp recombinase for genetic manipulation in deep mouse brain regions

Spatiotemporal control of gene expression or labeling is a valuable strategy for identifying functions of genes within complex neural circuits. Here, we develop a highly light-sensitive and efficient photoactivatable Flp recombinase (PA-Flp) that is suitable for genetic manipulation in vivo. The highly light-sensitive property of PA-Flp is ideal for activation in deep mouse brain regions by illumination with a noninvasive light-emitting diode. In addition, PA-Flp can be extended to the Cre-lox system through a viral vector as Flp-dependent Cre expression platform, thereby activating both Flp and Cre. Finally, we demonstrate that PA-Flp-dependent, Cre-mediated Ca(v)3.1 silencing in the medial septum increases object-exploration behavior in mice. Thus, PA-Flp is a noninvasive, highly efficient, and easy-to-use optogenetic module that offers a side-effect-free and expandable genetic manipulation tool for neuroscience research. © The Author(s) 2019.11Nsciescopu

Light-inducible receptor tyrosine kinases that regulate neurotrophin signalling

Receptor tyrosine kinases (RTKs) are a family of cell-surface receptors that have a key role in regulating critical cellular processes. Here, to understand and precisely control RTK signalling, we report the development of a genetically encoded, photoactivatable Trk (tropomyosin-related kinase) family of RTKs using a light-responsive module based on Arabidopsis thaliana cryptochrome 2. Blue-light stimulation (488-nm) of mammalian cells harbouring these receptors robustly upregulates canonical Trk signalling. A single light stimulus triggers transient signalling activation, which is reversibly tuned by repetitive delivery of blue-light pulses. In addition, the light-provoked process is induced in a spatially restricted and cell-specific manner. A prolonged patterned illumination causes sustained activation of extracellular signal-regulated kinase and promotes neurite outgrowth in a neuronal cell line, and induces filopodia formation in rat hippocampal neurons. These light-controllable receptors are expected to create experimental opportunities to spatiotemporally manipulate many biological processes both in vitro and in vivo. © 2014 Macmillan Publishers Limited.139391Nsciescopu

Antitumor Effects of Intra-Arterial Delivery of Albumin-Doxorubicin Nanoparticle Conjugated Microbubbles Combined with Ultrasound-Targeted Microbubble Activation on VX2 Rabbit Liver Tumors

Image-guided intra-arterial therapies play a key role in the management of hepatic malignancies. However, limited clinical outcomes suggest the need for new multifunctional drug delivery systems to enhance local drug concentration while reducing systemic adverse reactions. Therefore, we developed the albumin-doxorubicin nanoparticle conjugated microbubble (ADMB) to enhance therapeutic efficiency by sonoporation under exposure to ultrasound. ADMB demonstrated a size distribution of 2.33 ± 1.34 µm and a doxorubicin loading efficiency of 82.7%. The echogenicity of ADMBs was sufficiently generated in the 2–9 MHz frequency range and cavitation depended on the strength of the irradiating ultrasound. In the VX2 rabbit tumor model, ADMB enhanced the therapeutic efficiency under ultrasound exposure, compared to free doxorubicin. The intra-arterial administration of ADMBs sufficiently reduced tumor growth by five times, compared to the control group. Changes in the ADC values and viable tumor fraction supported the fact that the antitumor effect of ADMBs were enhanced by evidence of necrosis ratio (over 70%) and survival tumor cell fraction (20%). Liver toxicity was comparable to that of conventional therapies. In conclusion, this study shows that tumor suppression can be sufficiently maximized by combining ultrasound exposure with intra-arterial ADMB administration

Neurotrophin-3 regulates synapse development by modulating TrkC-PTPσ synaptic adhesion and intracellular signaling pathways

Neurotrophin-3 (NT-3) is a secreted neurotrophic factor that binds neurotrophin receptor tyrosine kinase C (TrkC), which in turn binds to presynaptic protein tyrosine phosphatase σ (PTPσ) to govern excitatory synapse development. However, whether and how NT-3 cooperates with the TrkC-PTPσ synaptic adhesion pathway and TrkC-mediated intracellular signaling pathways in rat cultured neurons has remained unclear. Here, we report that NT-3 enhances TrkC binding affinity for PTPσ. Strikingly, NT-3 treatment bidirectionally regulates the synaptogenic activity of TrkC: at concentrations of 10–25 ng/ml, NT-3 further enhanced the increase in synapse density induced by TrkC overexpression, whereas at higher concentrations, NT-3 abrogated TrkC-induced increases in synapse density. Semiquantitative immunoblotting and optogenetics-based imaging showed that 25 ng/ml NT-3 or light stimulation at a power that produced a comparable level of NT-3 (6.25 μW) activated only extracellular signal-regulated kinase (ERK) and Akt, whereas 100 ng/ml NT-3 (light intensity, 25 μW) further triggered the activation of phospholipase C-γ1 and CREB independently of PTPσ. Notably, disruption of TrkC intracellular signaling pathways, extracellular ligand binding, or kinase activity by point mutations compromised TrkC-induced increases in synapse density. Furthermore, only sparse, but not global, TrkC knock-down in cultured rat neurons significantly decreased synapse density, suggesting that intercellular differences in TrkC expression level are critical for its synapse-promoting action. Together, our data demonstrate that NT-3 is a key factor in excitatory synapse development that may direct higher-order assembly of the TrkC/PTPσ complex and activate distinct intracellular signaling cascades in a concentration-dependent manner to promote competition-based synapse development processes. © 2016 the authors115141sciescopu

Angiographic complete revascularization versus incomplete revascularization in patients with diabetes mellitus

Background Considering the nature of diabetes mellitus (DM) in coronary artery disease, it is unclear whether complete revascularization is beneficial or not in patients with DM. We investigated the clinical impact of angiographic complete revascularization in patients with DM. Methods A total of 5516 consecutive patients (2003 patients with DM) who underwent coronary stenting with 2nd generation drug-eluting stent were analyzed. Angiographic complete revascularization was defined as a residual SYNTAX (SYNergy between percutaneous coronary intervention with TAXus and cardiac surgery) score of 0. The patient-oriented composite outcome (POCO, including all-cause death, any myocardial infarction, and any revascularization) and target lesion failure (TLF) at three years were analyzed. Results Complete revascularization was associated with a reduced risk of POCO in DM population [adjusted hazard ratio (HR) 0.70, 95% confidence interval (CI) 0.52-0.93, p = 0.016], but not in non-DM population (adjusted HR 0.90, 95% CI 0.69-1.17, p = 0.423). The risk of TLF was comparable between the complete and incomplete revascularization groups in both DM (adjusted HR 0.75, 95% CI 0.49-1.16, p = 0.195) and non-DM populations (adjusted HR 1.11, 95% CI 0.75-1.63, p = 0.611). The independent predictors of POCO were incomplete revascularization, multivessel disease, left main disease and low ejection fraction in the DM population, and old age, peripheral vessel disease, and low ejection fraction in the non-DM population. Conclusions The clinical benefit of angiographic complete revascularization is more prominent in patients with DM than those without DM after three years of follow-up. Relieving residual disease might be more critical in the DM population than the non-DM population. Trial registration The Grand Drug-Eluting Stent registry NCT03507205.N

Efficacy and safety of dual antiplatelet therapy after coronary stenting in patients with chronic kidney disease.

BACKGROUND We compared efficacy and safety of short- (3 or 6 months) versus long-term (≥12 months) dual antiplatelet therapy (DAPT) after drug-eluting stent (DES) implantation, according to the presence of chronic kidney disease (CKD). METHODS Patient-level pooled analysis was performed with 7242 patients (87.2% with 2nd generation DES) from 5 randomized controlled trials. RESULTS In both CKD (1273 patients) and non-CKD (5969 patients) population, the rates of patient-oriented composite outcomes at 1-year (POCO, all-cause death, any myocardial infarction [MI], stroke and TIMI major bleeding) were not different between the short- and long-term DAPT (hazard ratio [HR] 1.19, 95% confidence interval [CI] 0.76-1.86, P=.449 in CKD population; HR 1.14, 95% CI 0.83-1.56, P=.434 in non-CKD population). The rates of coronary thrombotic events (any MI and definite/probable stent thrombosis) also did not differ between short- and long-term DAPT in either CKD or non-CKD population. As for bleeding events, long-term DAPT increased the TIMI major bleeding (HR 2.91, 95% CI 1.31-6.48, P=.009) in non-CKD population. The similar trend was observed with long-term DAPT in CKD population. But it did not reach statistical significance (HR 3.15, 95% CI 0.64-15.63, P=.160). CONCLUSIONS The rates of POCO and coronary thrombotic events were significantly higher in patients with CKD compared with those without CKD, which were not affected by short- or long-term DAPT. Higher bleeding incidence by long-term DAPT was only observed in non-CKD patients but not in CKD patients. Further large scale studies are warranted to confirm our findings

Optogenetic control of endogenous Ca2+ channels in vivo

Calcium (Ca2+) signals that are precisely modulated in space and time mediate a myriad of cellular processes, including contraction, excitation, growth, differentiation and apoptosis1. However, study of Ca2+ responses has been hampered by technological limitations of existing Ca2+-modulating tools. Here we present OptoSTIM1, an optogenetic tool for manipulating intracellular Ca2+ levels through activation of Ca2+-selective endogenous Ca2+ release−activated Ca2+ (CRAC) channels. Using OptoSTIM1, which combines a plant photoreceptor2,3 and the CRAC channel regulator STIM1 (ref. 4), we quantitatively and qualitatively controlled intracellular Ca2+ levels in various biological systems, including zebrafish embryos and human embryonic stem cells. We demonstrate that activating OptoSTIM1 in the CA1 hippocampal region of mice selectively reinforced contextual memory formation. The broad utility of OptoSTIM1 will expand our mechanistic understanding of numerous Ca2+-associated processes and facilitate screening for drug candidates that antagonize Ca2+ signals.131351sciescopu