Biology subjects

Kern, G.

Publications and source records attributed to Kern, G..

4 recordsLinked to original sources

bioRxiv2023

IL-4 shaping glutamatergic synapse like structures for more mature iPSC derived neuron phenotypes

The prototypical pleiotropic anti-inflammatory cytokine IL-4 not only acts on immune cells but also has important roles in the nervous system mediating antinociception and neuroregeneration. Therefore, we explored the expression of IL-4, its receptors IL4RA and IL13RA1 and downstream signaling components together with morphological and functional assays as well as transcriptomic profiling in human nociceptors differentiating from induced pluripotent stem cells (iNocs). IL-4 induced de novo formation of synaptic boutons immunoreactive for vesicular glutamate transporter vGLUT1 in iNocs which express both, components of the IL-4 receptor complex (IL-4RA and IL-13RA1) and signaling machinery (Jak1/2, STAT6, PKC isoforms, translation factor EiF4E) during differentiation. Pharmacological inhibition of these translational or cellular signaling components reduced the synaptogenic effect. IL-4 induced distinct transcriptomic changes associated with biological process ontologies for "neuron projection development", "axonogenesis" and "synapse", "cellular process involved in reproduction in multicellular organism", "regulation of membrane potential" and "calcium ion transmembrane transport". This partially reflected injury-induced transcriptional changes of mouse nerve injury models which contribute to regenerative processes in peripheral nerve but possibly also to reconnecting primary afferent neurons to their projections in the spinal dorsal horn and indicates a critical role for IL-4 in the control of developing and established neuronal networks.

neuroscience↗

bioRxiv2023

Protocol for mapping of the supplementary motor area using repetitive navigated transcranial magnetic stimulation

Structured abstractO_ST_ABSBackgroundC_ST_ABSDamage to the supplementary motor area (SMA) for example during surgery can lead to impairments of motor and language function. A detailed preoperative mapping of functional boarders of the SMA could therefore aid preoperative diagnostics in these patients. ObjectiveThe aim of this study was the development of a repetitive nTMS protocol for non-invasive functional mapping of the SMA while assuring effects are indeed caused by SMA stimulation rather than activation of M1. MethodsTo this purpose the SMA in the dominant hemisphere of twelve healthy subjects (28.2 {+/-} 7.7 years, 6 females) was mapped using repetitive nTMS at 20 Hz (120% RMT), while subjects performed a finger tapping task. The location of induced errors was marked in each subjects individual MRI. To further validate the protocol, effects of SMA stimulation were directly compared to effects of M1 stimulation in four different tasks. ResultsMapping of the SMA was possible for all subjects, yet varying effect sizes were observed. Stimulation of the SMA led to a significant reduction of finger taps compared to baseline (BL: 45 taps, SMA: 35.5 taps; p < 0.01). Line tracing, writing and targeting of circles was less accurate during SMA compared to M1 stimulation. ConclusionMapping of the SMA using repetitive nTMS is feasible. While errors induced in the SMA are not entirely independent of M1 due to the proximity of both regions, disruption of the SMA induces functionally distinct errors. These error maps can aid preoperative diagnostics in patients with SMA related lesions.

neuroscience↗

bioRxiv2021

NOCICEPTRA: Gene and microRNA signatures and their trajectories characterizing human iPSC-derived nociceptor maturation

Nociceptors are primary afferent neurons serving the reception of acute pain but also the transit into maladaptive pain disorders. Since native human nociceptors are hardly available for mechanistic functional research, and rodent models do not necessarily mirror human pathologies in all aspects, human iPSC-derived nociceptors (iDN) offer superior advantages as a human model system. Unbiased mRNA::microRNA co-sequencing, immunofluorescence staining and qPCR validations, revealed expression trajectories as well as miRNA target spaces throughout the transition of pluripotent cells into iDNs. mRNA and miRNA candidates emerged as regulatory hubs for neurite outgrowth, synapse development and ion channel expression. The exploratory data analysis tool NOCICEPTRA is provided as a containerized platform to retrieve experimentally determined expression trajectories, and to query custom gene sets for pathway and disease enrichments. Querying NOCICEPTRA for marker genes of cortical neurogenesis revealed distinct similarities and differences for cortical and peripheral neurons. The platform provides a public domain neuroresource to exploit the entire data sets and explore miRNA and mRNA as hubs regulating human nociceptor differentiation and function.

neuroscience↗

bioRxiv2018

Dynamics of human protein kinases linked to drug selectivity

Protein kinases are major drug targets, but the development of highly-selective inhibitors has been challenging due to the similarity of their active sites. The observation of distinct structural states of the fully-conserved Asp-Phe-Gly (DFG) loop has put the concept of conformational selection for the DFG-state at the center of kinase drug discovery. Recently, it was shown that Gleevec selectivity for the Tyr-kinases Abl was instead rooted in conformational changes after drug binding. Here, we investigate whether protein dynamics after binding is a more general paradigm for drug selectivity by characterizing the binding of several approved drugs to the Ser/Thr-kinase Aurora A. Using a combination of biophysical techniques, we propose a universal drug-binding mechanism, that rationalizes selectivity, affinity and long on-target residence time for kinase inhibitors. These new concepts, where protein dynamics in the drug-bound state plays the crucial role, can be applied to inhibitor design of targets outside the kinome.\n\neLife digestThe Ser/Thr kinase Aurora A is an important target for the development of new anticancer therapies. A longstanding question is how to specifically and effectively inhibit only this kinase in a background of over 550 protein kinases with very similar structures. To this end, understanding the inhibition mechanism of Aurora A by different drugs is essential. Here, we characterize the kinetic mechanism of three distinct kinase drugs, Gleevec (Imatinib), Danusertib (PHA739358) and AT9283 (Pyrazol-4-yl Urea) for Aurora A. We show that inhibitor affinities do not rely exclusively on the recognition of a specific conformation of the Asp-Phe-Gly loop of the kinase. Our quantitative kinetics data put forward an opposing mechanism in which a slow conformational change after drug binding (i.e., induced-fit step) dictates drug affinity.

cancer biology↗