Human iPSC-derived neurons and cerebral organoids establish differential effects of germline NF1 gene mutations

Neurofibromatosis type 1 (NF1) is a common neurodevelopmental disorder caused by a spectrum of distinct germline NF1 gene mutations, traditionally viewed as equivalent loss-of-function alleles. To specifically address the issue of mutational equivalency in a disease with considerable clinical heterogeneity, we engineered seven isogenic human induced pluripotent stem cell lines, each with a different NF1 patient NF1 mutation, to identify potential differential effects of NF1 mutations on human central nervous system cells and tissues. Although all mutations increased proliferation and RAS activity in 2D neural progenitor cells (NPCs) and astrocytes, we observed striking differences between NF1 mutations on 2D NPC dopamine levels, and 3D NPC proliferation, apoptosis, and neuronal differentiation in developing cerebral organoids. Together, these findings demonstrate differential effects of NF1 gene mutations at the cellular and tissue levels, suggesting that the germline NF1 gene mutation is one factor that underlies clinical variability

Patient-derived iPSC-cerebral organoid modeling of the 17q11.2 microdeletion syndrome establishes CRLF3 as a critical regulator of neurogenesis

Neurodevelopmental disorders are often caused by chromosomal microdeletions comprising numerous contiguous genes. A subset of neurofibromatosis type 1 (NF1) patients with severe developmental delays and intellectual disability harbors such a microdeletion event on chromosome 17q11.2, involving the NF1 gene and flanking regions (NF1 total gene deletion [NF1-TGD]). Using patient-derived human induced pluripotent stem cell (hiPSC)-forebrain cerebral organoids (hCOs), we identify both neural stem cell (NSC) proliferation and neuronal maturation abnormalities in NF1-TGD hCOs. While increased NSC proliferation results from decreased NF1/RAS regulation, the neuronal differentiation, survival, and maturation defects are caused by reduced cytokine receptor-like factor 3 (CRLF3) expression and impaired RhoA signaling. Furthermore, we demonstrate a higher autistic trait burden in NF1 patients harboring a deleterious germline mutation in the CRLF3 gene (c.1166T\u3eC, p.Leu389Pro). Collectively, these findings identify a causative gene within the NF1-TGD locus responsible for hCO neuronal abnormalities and autism in children with NF1

Origin of Thermally Stimulated Currents in Sodium Silicate Glasses

Thermally stimulated polarization and depolarization currents have been measured for silicate glasses containing from 4 to 14.8 mol% Na2O. Insulating electrodes and the microstructure of these phase separated glasses affect the observed current peaks which are attributed to dipole orientation polarization or interfacial polarization

Upregulation of synaptotagmin IV inhibits transmitter release in PC12 cells with targeted synaptotagmin I knockdown

Abstract Background The function of synaptotagmins (syt) in Ca2+-dependent transmitter release has been attributed primarily to Ca2+-dependent isoforms such as syt I. Recently, syt IV, an inducible Ca2+-independent isoform has been implicated in transmitter release. We postulated that the effects of syt IV on transmitter release are dependent on the expression of syt I. Results To test this, we increased syt IV expression in PC12 cells by either upregulation with forskolin treatment or overexpression with transfection. Two separately generated stable PC12 cell lines with syt I expression abolished by RNAi targeting were used and compared to control cells. We measured catecholamine release from single vesicles by amperometry and neuropeptide Y release from populations of cells by an immunoassay. In syt I targeted cells with forskolin-induced syt IV upregulation, amperometry measurements showed a reduction in the number of release events and the total amount of transmitter molecules released per cell. In cells with syt IV overexpressed, similar amperometry results were obtained, except that the rate of expansion for full fusion was slowed. Neuropeptide Y (NPY) release from syt I knockdown cells was decreased, and overexpression of syt IV did not rescue this effect. Conclusions These data support an inhibitory effect of syt IV on release of vesicles and their transmitter content. The effect became more pronounced when syt I expression was abolished.</p

The effect of approach/avoidance training on alcohol consumption is mediated by change in alcohol action tendency

Contains fulltext : 126061.pdf (publisher's version ) (Open Access)Training people to respond to alcohol images by making avoidance joystick movements can affect subsequent alcohol consumption, and has shown initial efficacy as a treatment adjunct. However, the mechanisms that underlie the training's efficacy are unknown. The present study aimed to determine 1) whether the training's effect is mediated by a change in action tendency or a change in selective attention, and 2) whether the training's effect is moderated by individual differences in working memory capacity (WMC). Three groups of social drinkers (total N = 74) completed either approach-alcohol training, avoid-alcohol training or a sham-training on the Approach-Avoidance Task (AAT). Participants' WMC was assessed prior to training, while their alcohol-related action tendency and selective attention were assessed before and after the training on the recently developed Selective-Attention/Action Tendency Task (SA/ATT), before finally completing an alcohol taste-test. There was no significant main effect of approach/avoidance training on alcohol consumption during the taste-test. However, there was a significant indirect effect of training on alcohol consumption mediated by a change in action tendency, but no indirect effect mediated by a change in selective attention. There was inconsistent evidence of WMC moderating training efficacy, with moderation found only for the effect of approach-alcohol training on the AAT but not on the SA/ATT. Thus approach/avoidance training affects alcohol consumption specifically by changing the underlying action tendency. Multiple training sessions may be required in order to observe more substantive changes in drinking behaviour.10 p

Effects of Chemically Doped Bioactive Borate Glass on Neuron Regrowth and Regeneration

Peripheral nerve injuries present challenges to regeneration. Currently, the gold standard for nerve repair is an autograft that results in another region of the body suffering nerve damage. Previously, bioactive borate glass (BBG) has been studied in clinical trials to treat patients with non-healing wounds, and we have reported that BBG is conducive for soft tissue repair. BBG provides structural support, degrades in a non-cytotoxic manner, and can be chemically doped. Here, we tested a wide range of chemical compounds that are reported to have neuroprotective characteristics to promote regeneration of peripheral neurons after traumatic injury. We hypothesized that chemical dopants added in trace amounts to BBG would improve neuronal survival and neurite outgrowth from dorsal root ganglion (DRG) explants. We measured neurite outgrowth from whole DRG explants, and survival rates of dissociated neurons and support cells that comprise the DRG. Results show that chemically doped BBGs have differentially variable effects on neuronal survival and outgrowth, with iron, gallium, and zinc improving outgrowth of neurons, and iodine causing the most detriment to neurons. Because chemically doped BBGs support increased nerve regrowth and survival, they show promise for use in peripheral nerve regeneration