Neuronal network dysfunction in a model for Kleefstra syndrome mediated by enhanced NMDAR signaling

Kleefstra syndrome (KS) is a neurodevelopmental disorder caused by mutations in the histone methyltransferase EHMT1. To study the impact of decreased EHMT1 function in human cells, we generated excitatory cortical neurons from induced pluripotent stem (iPS) cells derived from KS patients. Neuronal networks of patient-derived cells exhibit network bursting with a reduced rate, longer duration, and increased temporal irregularity compared to control networks. We show that these changes are mediated by upregulation of NMDA receptor (NMDAR) subunit 1 correlating with reduced deposition of the repressive H3K9me2 mark, the catalytic product of EHMT1, at the GRIN1 promoter. In mice EHMT1 deficiency leads to similar neuronal network impairments with increased NMDAR function. Finally, we rescue the KS patient-derived neuronal network phenotypes by pharmacological inhibition of NMDARs. Summarized, we demonstrate a direct link between EHMT1 deficiency and NMDAR hyperfunction in human neurons, providing a potential basis for more targeted therapeutic approaches for KS

Synthesis of γ-, δ-, and ε-Lactams by Asymmetric Transfer Hydrogenation of N-(tert-Butylsulfinyl)iminoesters

Highly enantiomerically enriched γ- and δ-lactams have been prepared by a simple and very efficient procedure that involves the asymmetric transfer hydrogenation of N-(tert-butylsulfinyl)iminoesters followed by desulfinylation of the nitrogen atom and spontaneous cyclization to the desired lactams during the basic workup procedure. Five- and six-membered ring lactams bearing aromatic, heteroaromatic, and aliphatic substituents have been obtained in very high yields and ee’s up to >99%. A slight modification of the procedure also allowed the preparation of ε-lactams in good yields and very high enantioselectivities. Both enantiomers of the final lactams could be prepared with equal efficiency by changing the absolute configuration of the sulfinyl chiral auxiliary

High serotonin levels during brain development alter the structural input-output connectivity of neural networks in the rat somatosensory layer IV

Contains fulltext : 125661.pdf (publisher's version ) (Open Access)Homeostatic regulation of serotonin (5-HT) concentration is critical for "normal" topographical organization and development of thalamocortical (TC) afferent circuits. Down-regulation of the serotonin transporter (SERT) and the consequent impaired reuptake of 5-HT at the synapse, results in a reduced terminal branching of developing TC afferents within the primary somatosensory cortex (S1). Despite the presence of multiple genetic models, the effect of high extracellular 5-HT levels on the structure and function of developing intracortical neural networks is far from being understood. Here, using juvenile SERT knockout (SERT(-/-)) rats we investigated, in vitro, the effect of increased 5-HT levels on the structural organization of (i) the TC projections of the ventroposteromedial thalamic nucleus toward S1, (ii) the general barrel-field pattern, and (iii) the electrophysiological and morphological properties of the excitatory cell population in layer IV of S1 [spiny stellate (SpSt) and pyramidal cells]. Our results confirmed previous findings that high levels of 5-HT during development lead to a reduction of the topographical precision of TCA projections toward the barrel cortex. Also, the barrel pattern was altered but not abolished in SERT(-/-) rats. In layer IV, both excitatory SpSt and pyramidal cells showed a significantly reduced intracolumnar organization of their axonal projections. In addition, the layer IV SpSt cells gave rise to a prominent projection toward the infragranular layer Vb. Our findings point to a structural and functional reorganization of TCAs, as well as early stage intracortical microcircuitry, following the disruption of 5-HT reuptake during critical developmental periods. The increased projection pattern of the layer IV neurons suggests that the intracortical network changes are not limited to the main entry layer IV but may also affect the subsequent stages of the canonical circuits of the barrel cortex

Modulation of Mitochondriotropic Properties of Cyanine Dyes by in Organello Copper-Free Click Reaction

Cyanine dyes show a general propensity to localize to polarized mitochondria. This mitochondriotropism was used to perform a copper-free click reaction in the mitochondria of living cells. The in organello reaction of a Cy3 and Cy5 dye led to a product that was easily traceable by Förster resonance energy transfer (FRET). As determined by confocal laser scanning microscopy, the Cy3-Cy5 conjugate showed enhanced retention in mitochondria as compared to the starting compounds. This enhancement of a favorable property can be achieved by synthesis in organello but not outside mitochondria

Modulation of mitochondriotropic properties of cyanine dyes by in organello copper-free click reaction

Cyanine dyes show a general propensity to localize to polarized mitochondria. This mitochondriotropism was used to perform a copper-free click reaction in the mitochondria of living cells. The in organello reaction of a Cy3 and Cy5 dye led to a product that was easily traceable by Förster resonance energy transfer (FRET). As determined by confocal laser scanning microscopy, the Cy3-Cy5 conjugate showed enhanced retention in mitochondria as compared to the starting compounds. This enhancement of a favorable property can be achieved by synthesis in organello but not outside mitochondria

The Object Space Task reveals increased expression of cumulative memory in a mouse model of Kleefstra syndrome

Contains fulltext : 222203.pdf (publisher's version ) (Open Access

The Cytoskeletal Adaptor Obscurin-Like 1 Interacts with the Human Papillomavirus 16 (HPV16) Capsid Protein L2 and Is Required for HPV16 Endocytosis

The human papillomavirus (HPV) capsid protein L2 is essential for viral entry. To gain a deeper understanding of the role of L2, we searched for novel cellular L2-interacting proteins. A yeast two-hybrid analysis uncovered the actin-depolymerizing factor gelsolin, the membrane glycoprotein dysadherin, the centrosomal protein 68 (Cep68), and the cytoskeletal adaptor protein obscurin-like 1 protein (OBSL1) as putative L2 binding molecules. Pseudovirus (PsV) infection assays identified OBSL1 as a host factor required for gene transduction by three oncogenic human papillomavirus types, HPV16, HPV18, and HPV31. In addition, we detected OBSL1 expression in cervical tissue sections and noted the involvement of OBSL1 during gene transduction of primary keratinocytes by HPV16 PsV. Complex formation of HPV16 L2 with OBSL1 was demonstrated in coimmunofluorescence and coimmunoprecipitation studies after overexpression of L2 or after PsV exposure. We observed a strong colocalization of OBSL1 with HPV16 PsV and tetraspanin CD151 at the plasma membrane, suggesting a role for OBSL1 in viral endocytosis. Indeed, viral entry assays exhibited a reduction of viral endocytosis in OBSL1-depleted cells. Our results suggest OBSL1 as a novel L2-interacting protein and endocytosis factor in HPV infection. IMPORTANCE Human papillomaviruses infect mucosal and cutaneous epithelia, and the high-risk HPV types account for 5% of cancer cases worldwide. As recently discovered, HPV entry occurs by a clathrin-, caveolin-, and dynamin-independent endocytosis via tetraspanin-enriched microdomains. At present, the cellular proteins involved in the underlying mechanism of this type of endocytosis are under investigation. In this study, the cytoskeletal adaptor OBSL1 was discovered as a previously unrecognized interaction partner of the minor capsid protein L2 and was identified as a proviral host factor required for HPV16 endocytosis into target cells. The findings of this study advance the understanding of a so far less well-characterized endocytic pathway that is used by oncogenic HPV subtypes

A modular approach for multifunctional polymersomes with controlled adhesive properties

The bottom-up approach in synthetic biology involves the engineering of synthetic cells by designing biological and chemical building blocks, which can be combined in order to mimic cellular functions. The first step for mimicking a living cell is the design of an appropriate compartment featuring a multifunctional membrane. This is of particular interest since it allows for the selective attachment of different groups or molecules to the membrane. In this context, we report on a modular approach for polymeric vesicles, so-called polymersomes, with a multifunctional surface, namely hydroxyl, alkyne and acrylate groups. We demonstrate that the surface of the polymersome can be functionalized to facilitate imaging, via dye molecules, or to improve the specific adhesion to surfaces by using a biotin functionalization. This generally applicable multifunctionality allows for the covalent integration of various molecules in the membrane of a synthetic cell