Regulation of neural gene transcription by optogenetic inhibition of the RE1-silencing transcription factor.

Optogenetics provides new ways to activate gene transcription; however, no attempts have been made as yet to modulate mammalian transcription factors. We report the light-mediated regulation of the repressor element 1 (RE1)-silencing transcription factor (REST), a master regulator of neural genes. To tune REST activity, we selected two protein domains that impair REST-DNA binding or recruitment of the cofactor mSin3a. Computational modeling guided the fusion of the inhibitory domains to the light-sensitive Avena sativa light-oxygen-voltage-sensing (LOV) 2-phototrophin 1 (AsLOV2). By expressing AsLOV2 chimeras in Neuro2a cells, we achieved light-dependent modulation of REST target genes that was associated with an improved neural differentiation. In primary neurons, light-mediated REST inhibition increased Na(+)-channel 1.2 and brain-derived neurotrophic factor transcription and boosted Na(+) currents and neuronal firing. This optogenetic approach allows the coordinated expression of a cluster of genes impinging on neuronal activity, providing a tool for studying neuronal physiology and correcting gene expression changes taking place in brain diseases.

Diabetic ketoacidosis with central nervous system involvement: Conventional and advanced magnetic resonance neuroimaging findings.

Diabetic ketoacidosis (DKA) is a serious complication in children with diabetes mellitus type 1 (DM1). In rare and severe cases DKA may be complicated by cerebral edema, central brain herniation and cerebral infarctions. We present the magnetic resonance imaging findings in a child with DKA and central nervous system involvement; diffusion tensor imaging (DTI) and functional MRI (fMRI) were performed to assess the white matter integrity of sensory pathways and cortical sensory processing. Conventional imaging showed bilateral uncal herniation, effacement of the perimesencephalic cisterns, wide ischemic lesions in the posterior cerebral artery (PCA) territories, sagging brainstem and Duret's hemorrhage consistent with signs of central brain herniation and intracranial hypertension. Advanced MRI showed a possible left-sided cortical reorganization for sensory function, with underlying left cortico-talamic and cortico-spinal pathways less severely impaired. Knowledge of the full framework in these conditions is of vital importance for timely patient management; advanced neuroimaging techniques may be considered as prognostic indicators in those cases with extensive involvement of eloquent brain areas.

Multi-Magnet Cochlear Implant Technology and Magnetic Resonance Imaging: The Safety Issue.

Despite the spread of novel-generation cochlear-implant (CI) magnetic systems, access to magnetic resonance imaging (MRI) for CI recipients is still limited due to safety concerns. The aim of this study is to assess and record the experiences of Hires Ultra 3D (Advanced Bionics) recipients who underwent an MRI examination. A multicentric European survey about this topic was conducted focusing on safety issues, and the results were compared with the current literature. We collected a total of 65 MRI scans performed in 9 otologic referral centers for a total of 47 Hires Ultra 3D recipients, including, for the first time, 2 children and 3 teenagers. Preventive measures were represented by scanning time and sedation for children. Head wrapping was used in eight cases, and six of the eight cases received local anesthesia, even if both measures were not needed. Only three patients complained of pain (3/65 examinations, 4.6%) due to the tight head bandage, and one of the three cases required MRI scan interruption. No other adverse events were reported. We believe that these results should encourage MRI execution in accordance with manufacturer recommendations for Ultra 3D recipients.

An uncommon presentation of Wernicke-Korsakoff's syndrome in pregnancy: Case report.

Wernicke's encephalopathy is an acute neuropsychiatric syndrome resulting from severe thiamine (vitamin B1) deficiency. Symptoms occur with an acute onset and may vary according to the brain area involved. Altered consciousness is the most common clinical feature, together with ocular abnormalities and ataxia. We report the case of a pregnant women affected by pre-gestational hyperthyroidism that caused an uncommon presentation of Wernicke's encephalopathy. Symptoms differed from the classic triad and diagnosis was made possible by a thorough analysis of anamnestic factors and brain MRI. Alongside thiamine supplementation, a multidisciplinary approach which included physiokinesis and a phoniatric support was fundamental for the patient's recovery.

The VersaLive platform enables microfluidic mammalian cell culture for versatile applications.

Microfluidic-based cell culture allows for precise spatio-temporal regulation of microenvironment, live cell imaging and better recapitulation of physiological conditions, while minimizing reagents' consumption. Despite their usefulness, most microfluidic systems are designed with one specific application in mind and usually require specialized equipment and expertise for their operation. All these requirements prevent microfluidic-based cell culture to be widely adopted. Here, we designed and implemented a versatile and easy-to-use perfusion cell culture microfluidic platform for multiple applications (VersaLive) requiring only standard pipettes. Here, we showcase the multiple uses of VersaLive (e.g., time-lapse live cell imaging, immunostaining, cell recovery, cell lysis, plasmid transfection) in mammalian cell lines and primary cells. VersaLive could replace standard cell culture formats in several applications, thus decreasing costs and increasing reproducibility across laboratories. The layout, documentation and protocols are open-source and available online at https://versalive.tigem.it/ .

MRI in Late-Onset Rasmussen Encephalitis: A Long-Term Follow-Up Study.

Late-onset Rasmussen encephalitis (LoRE) is a rare unihemispheric progressive inflammatory disorder causing neurological deficits and epilepsy. The long-term radiological evolution has never been fully described. We retrospectively analyzed the MR images of 13 LoRE patients from a total of 136 studies, and searched for focal areas of volume loss or signal intensity abnormality in grey matter or white matter. Each subject had a median of nine MRI studies (IQR 7-13). Frontal and temporal lobes were the most affected regions (13/13 and 8/13, respectively) and showed the greatest worsening over time in terms of atrophic changes (9/13 and 5/8, respectively). A milder cortical atrophy was found in the insular and parietal lobes. The caudate nucleus was affected in seven patients. Hyperintensities of grey matter and white matter on T2-WI and FLAIR images were observed in all patients, and transiently in eight patients. In two cases out of the latter patients, these transient alterations evolved into atrophy of the same region. Disease duration was significantly associated with signal abnormalities in the grey matter at last follow-up. LoRE MRI alterations are milder, and their progression is markedly slower compared to radiological findings described in the childhood form.

Engineering REST-Specific Synthetic PUF Proteins to Control Neuronal Gene Expression: A Combined Experimental and Computational Study.

Regulation of gene transcription is an essential mechanism for differentiation and adaptation of organisms. A key actor in this regulation process is the repressor element 1 (RE1)-silencing transcription factor (REST), a transcriptional repressor that controls more than 2000 putative target genes, most of which are neuron-specific. With the purpose of modulating REST expression, we exploited synthetic, ad hoc designed, RNA binding proteins (RBPs) able to specifically target and dock to REST mRNA. Among the various families of RBPs, we focused on the Pumilio and FBF (PUF) proteins, present in all eukaryotic organisms and controlling a variety of cellular functions. Here, a combined experimental and computational approach was used to design and test 8- and 16-repeat PUF proteins specific for REST mRNA. We explored the conformational properties and atomic features of the PUF-RNA recognition code by Molecular Dynamics simulations. Biochemical assays revealed that the 8- and 16-repeat PUF-based variants specifically bind the endogenous REST mRNA without affecting its translational regulation. The data also indicate a key role of stacking residues in determining the binding specificity. The newly characterized REST-specific PUF-based constructs act as excellent RNA-binding modules and represent a versatile and functional platform to specifically target REST mRNA and modulate its endogenous expression.

MiRNAs confer phenotypic robustness to gene networks by suppressing biological noise.

miRNAs are small non-coding RNAs able to modulate target gene expression. It has been postulated that miRNAs confer robustness to biological processes, but clear experimental evidence is still missing. Here, using a synthetic biological approach, we demonstrate that microRNAs provide phenotypic robustness to transcriptional regulatory networks by buffering fluctuations in protein levels. We construct a network motif in mammalian cells exhibiting a 'toggle-switch' phenotype in which two alternative protein expression levels define its ON and OFF states. The motif consists of an inducible transcription factor that self-regulates its own transcription and that of a miRNA against the transcription factor itself. We confirm, using mathematical modelling and experimental approaches, that the microRNA confers robustness to the toggle-switch by enabling the cell to maintain and transmit its state. When absent, a dramatic increase in protein noise level occurs, causing the cell to randomly switch between the two states.

Design and construction of a versatile synthetic network for bistable gene expression in mammalian systems.

We constructed and modeled a novel synthetic network which may be able to exhibit bistable expression of a reporter gene in mammalian cells. This network is based on an aptamer-fused short-hairpin RNA (shRNA) directed against a single mRNA encoding both a EGFP reporter gene and the repressor tTR-KRAB, which, in turn, represses transcription of the shRNA. The activity of the shRNA can be controlled by an inducer molecule (theophylline) which prevents the aptamer-fused shRNA to be properly processed. Repression of the tTR-KRAB can be relieved by treatment with doxycyline. This reciprocal negative feed-back loop can exhibit a bistable response, as shown through the mathematical analysis performed here. Specifically, the network can be controlled to induce sustained expression of a shRNA, or the reporter gene, with a transient input of two different inducer molecules.