Biology subjects

Reinhard, J.

Publications and source records attributed to Reinhard, J..

4 recordsLinked to original sources

bioRxiv2022

Brevican, Neurocan, Tenascin-C and Tenascin-R Act as Important Regulators of the Interplay between Perineuronal Nets, Synaptic Integrity, Inhibitory Interneurons and Otx2

Fast-spiking parvalbumin interneurons are critical for the function of mature cortical inhibitory circuits. Most of these neurons are enwrapped by a specialized extracellular matrix structure (ECM) called perineuronal net (PNN), which can regulate their synaptic input. In this study, we investigated the relationship between PNNs, parvalbumin interneurons and synaptic distribution on these cells in the adult primary visual cortex (V1) of quadruple knockout mice deficient for the ECM molecules brevican, neurocan, tenascin-C and tenascin-R. We used super-resolution structured illumination microscopy (SIM) to analyze PNN structure and associated synapses. Additionally, we examined parvalbumin and calretinin interneuron populations. We observed a reduction in the number of PNN-enwrapped cells and a clear disorganization of the PNN structure in the quadruple knockout V1. This was accompanied by an imbalance of inhibitory and excitatory synapses with a reduction of inhibitory and an increase of excitatory synaptic elements along the PNNs. Also, the number of parvalbumin interneurons was reduced in the quadruple knockout, while calretinin interneurons, which do not wear PNNs did not display differences in number. Interestingly, we found the transcription factor Otx2 homeoprotein positive cell population also reduced. Otx2 is crucial for parvalbumin and PNN maturation and a positive feedback loop between these parameters has been described. Collectively, these data indicate an important role of brevican, neurocan, tenascin-C and tenascin-R in regulating the interplay between PNNs, inhibitory interneurons, synaptic distribution as well as Otx2 in the V1.

neuroscience↗

bioRxiv2022

Protein profiling of WERI RB1 and etoposide resistant WERI ETOR reveals new insights into topoisomerase inhibitor resistance in retinoblastoma

Chemotherapy resistance is one of the reasons for eye loss in patients with retinoblastoma (RB). RB chemotherapy resistance has been studied in different cell culture models such as WERI RB1. In addition, chemotherapy resistant RB subclones like the etoposide resistant WERI ETOR cell line have been established to improve the understanding of chemotherapy resistance in RB. The objective of this study was to characterize cell line models of an etoposide sensitive WERI RB1 and its etoposide resistant subclone WERI ETOR by proteomic analysis. Subsequently, quantitative proteomic data served for correlation analysis with known drug perturbation profiles. Methodically, WERI RB1 and WERI ETOR were cultured and prepared for quantitative mass spectrometry (MS). This was carried out in a data-independent acquisition (DIA) mode (Sequential Window Acquisition of All Theoretical Mass Spectra, SWATH-MS). The raw SWATH files were processed using neural networks in a library free mode along with machine learning algorithms. Pathway enrichment was performed using the REACTOME pathway resource and correlated to the Molecular Signature Database (MSigDB) hallmark gene set collections for functional annotation. Furthermore, a drug connectivity analysis using the L1000 database was used to correlate the mechanism-of-action (MOA) for different anticancer reagents to WERI RB1/WERI ETOR signatures. A total of 4,756 proteins were identified across all samples, showing a distinct clustering between the groups. Of these proteins, 64 were significantly altered (q < 0.05 & log2FC |>2|, 22% higher in WERI ETOR). Pathway analysis revealed an enriched metabolic pathway for "retinoid metabolism and transport" in WERI ETOR and for "sphingolipid de novo biosynthesis" in WERI RB1. In addition, this study revealed similar protein signatures of topoisomerase inhibitors in WERI ETOR as well as ATPase inhibitors, acetylcholine receptor antagonists and vascular endothelial growth factor receptor (VEGFR) inhibitors in WERI RB1. In this study, WERI RB1 and WERI ETOR were analyzed as a cell line model for chemotherapy resistance in RB using data-independent MS. The global proteome identified activation of "sphingolipid de novo biosynthesis" in WERI RB1 and revealed future potential treatment options for etoposide resistance in RB.

cancer biology↗

bioRxiv2020

Nested versus independent sampling: Solving the mystery of contradictory species-area relationships

AO_SCPLOWBSTRACTC_SCPLOWSpecies-area relationships (SARs) describe how the number of species increases with the size of the area surveyed, and they usually take the shape of a power law on regional spatial scales. A meta-review of empirical data has shown that the exponent of the power law is on average larger when the areas are sampled in a nested manner, compared to sampling of independent areas such as islands of different sizes. As this is in contrast to ecological reasoning, we performed computer simulations of three qualitatively different models that generate species distributions in space and time by the mechanisms of speciation, dispersal, and extinction. We find that in all cases and over a wide parameter range the SARs obtained by nested sampling have a smaller slope in the regional scale than those obtained by independent sampling. We explain the discrepancy to the empirical data by the different spatial scales on which the two types of empirical investigations were performed.

ecology↗

bioRxiv2019

Systematic cysteine-crosslinking in native membranes establishes the transmembrane architecture in Ire1 clusters

The endoplasmic reticulum (ER) is a key organelle of membrane biogenesis and crucial for the folding of both membrane and secretory proteins. Sensors of the unfolded protein response (UPR) monitor the unfolded protein load in the ER and convey effector functions for maintaining ER homeostasis. Aberrant compositions of the ER membrane, referred to as lipid bilayer stress, are equally potent activators of the UPR. How the distinct signals from lipid bilayer stress and unfolded proteins are processed by the conserved UPR transducer Ire1 remains unknown. Here, we have generated a functional, cysteine-less variant of Ire1 and performed systematic cysteine crosslinking experiments in native membranes to establish its transmembrane architecture in signaling-active clusters. We show that the transmembrane helices of two neighboring Ire1 molecules adopt an X-shaped configuration independent of the primary cause for ER stress. This suggests that different forms of stress converge in a common, signaling-active transmembrane architecture of Ire1. SummaryThe endoplasmic reticulum (ER) is a hotspot of lipid biosynthesis and crucial for the folding of membrane and secretory proteins. The unfolded protein response (UPR) controls the size and folding capacity of the ER. The conserved UPR transducer Ire1 senses both unfolded proteins and aberrant lipid compositions to mount adaptive responses. Using a biochemical assay to study Ire1 in signaling-active clusters, Vath et al. provide evidence that the neighboring transmembrane helices of clustered Ire1 form an X irrespectively of the primary cause of ER stress. Hence, different forms of ER stress converge in a common, signaling-active transmembrane architecture of Ire1.

biochemistry↗