Culture of dissociated hippocampal neurons

Optical Regulation of Class C GPCRs by Photoswitchable Orthogonal Remotely Tethered Ligands

G protein-coupled receptors (GPCRs) respond to a wide range of extracellular cues to initiate complex downstream signaling cascades that control myriad aspects of cell function. Despite a long-standing appreciation of their importance to both basic physiology and disease treatment, it remains a major challenge to understand the dynamic activation patterns of GPCRs and the mechanisms by which they modulate biological processes at the molecular, cellular, and tissue levels. Unfortunately, classical methods of pharmacology and genetic knockout are often unable to provide the requisite precision needed to probe such questions. This is an especially pressing challenge for the class C GPCR family which includes receptors for the major excitatory and inhibitory neurotransmitters, glutamate and GABA, which signal in a rapid, spatially-delimited manner and contain many different subtypes whose roles are difficult to disentangle. The desire to manipulate class C GPCRs with spatiotemporal precision, genetic targeting, and subtype specificity has led to the development of a variety of photopharmacological tools. Of particular promise are the photoswitchable orthogonal remotely tethered ligands ("PORTLs") which attach to self-labeling tags that are genetically encoded into full length, wild-type metabotropic glutamate receptors (mGluRs) and allow the receptor to be liganded and un-liganded in response to different wavelengths of illumination. While powerful for studying class C GPCRs, a number of detailed considerations must be made when working with these tools. The protocol included here should provide a basis for the development, characterization, optimization, and application of PORTLs for a wide range of GPCRs.

Cultivation of Purified Primary Purkinje Cells from Rat Cerebella

Primary neurons are difficult to cultivate because they are often part of a complex tissue, and synaptically connected to numerous other cell types. These circumstances often prevent us from unveiling molecular and metabolic mechanisms of distinct cells, as functional signals or assays cannot clearly be correlated with them due to interfering signals from other parts of the culture. We therefore present an up-to-date method for obtaining a highly purified neuronal culture of Purkinje cells. In the past, Purkinje cells were successfully isolated from young mouse cerebella, but this protocol was never adapted to other mammals. We therefore provide an updated and adjusted protocol for Purkinje cell isolation from rat instead of mouse cerebella. To purify Purkinje cells, we obtained perinatal rat cerebella, dissociated them and performed a Percoll gradient centrifugation to segregate the smaller and larger cell fractions. In a second step, we performed an immunopanning procedure to enrich only Purkinje cells from the large cell fraction. Based on former protocols, we used a different antibody for the immunopanning procedure and adjusted several aspects from the initial protocol to improve the yield and vitality of Purkinje cells. We provide RT-qPCR-based purity data obtained with this protocol and show the behaviour and the growth of these purified Purkinje cells. We provide a highly reproducible purification protocol for Purkinje cell cultures of high purity that allows functional analysis and downstream assays on living rat Purkinje cells and further morphological growth analysis in future.

Systematic Localization and Identification of SUMOylation Substrates in Knock-In Mice Expressing Affinity-Tagged SUMO1

Protein SUMOylation is a posttranslational protein modification that is emerging as a key regulatory process in neurobiology. To date, however, SUMOylation in vivo has only been studied cursorily. Knock-in mice expressing His6-HA-SUMO1 from the Sumo1 locus allow for the highly specific localization and identification of endogenous SUMO1 substrates under physiological and pathophysiological conditions. By making use of the HA-tag and using wild-type mice for highly stringent negative control samples, SUMO1 targets can be specifically localized in and purified from cultured mouse nerve cells and mouse tissues.