Biology subjects

Welle, A.

Publications and source records attributed to Welle, A..

4 recordsLinked to original sources

bioRxiv2022

Brain injuries and complex motor learning suppress Olig2 in a subpopulation of oligodendrocyte precursor cells

Oligodendrocyte precursor cells (OPCs) are uniformly distributed in the mammalian brain, however their function is rather heterogeneous in respect to their origin, location, receptor/channel expression and age. The basic helix-loop-helix transcription factor Olig2 is expressed in all OPCs as a pivotal determinant of their differentiation. Here, we identified a subset (2-26%) of OPCs lacking Olig2 in various brain regions including cortex, corpus callosum, CA1 and dentate gyrus. These Olig2 negative (Olig2neg) OPCs were enriched in the juvenile brain and decreased subsequently with age, being rarely detectable in the adult brain. However, the loss of this population was not due to apoptosis or microglia-dependent phagocytosis. Unlike Olig2pos OPCs, these subset cells could not be labelled for the mitotic marker Ki67. And, accordingly, BrdU was incorporated only by a three-day long-term labeling but not by a two-hour short pulse, suggesting these cells do not proliferate any more but were derived from proliferating OPCs. The Olig2neg OPCs exhibited a less complex morphology than Olig2pos ones. Olig2neg OPCs preferentially remain in a precursor stage rather than differentiating into highly branched oligodendrocytes. Changing the adjacent brain environment, e.g. by acute injuries or by complex motor learning tasks stimulated the transition of Olig2pos OPCs to Olig2neg cells in the adult. Taken together, our results demonstrate that OPCs transiently suppress Olig2 upon changes of the brain activity. Table of Contents Image O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=145 SRC="FIGDIR/small/496631v1_ufig1.gif" ALT="Figure 1"> View larger version (51K): org.highwire.dtl.DTLVardef@1f8bc79org.highwire.dtl.DTLVardef@11dd807org.highwire.dtl.DTLVardef@51d2e9org.highwire.dtl.DTLVardef@1edf9a1_HPS_FORMAT_FIGEXP M_FIG C_FIG Main points: A subset of OPCs do not express Olig2, of which population peaks in the juvenile brain while wanes with age. Plastic changes of the brain by acute injuries or complex motor learning stop the expression of Olig2 in OPCs.

neuroscience↗

bioRxiv2022

Compound interaction screen on a photoactivatable cellulose membrane (CISCM) identifies drug targets

Identifying the protein targets of drugs is an important but tedious process. Existing proteomic approaches enable unbiased target identification but lack the throughput needed to screen larger compound libraries. Here, we present a compound interaction screen on a photoactivatable cellulose membrane (CISCM) that enables target identification of several drugs in parallel. To this end, we use diazirine-based undirected photoaffinity labeling (PAL) to immobilize compounds on cellulose membranes. Functionalized membranes are then incubated with protein extract and specific targets are identified via quantitative affinity purification and mass spectrometry. CISCM reliably identifies known targets of natural products in less than three hours of analysis time per compound. In summary, we show that combining undirected photoimmobilization of compounds on cellulose with quantitative interaction proteomics provides an efficient means to identify the targets of natural products.

biochemistry↗

bioRxiv2019

A one-step biofunctionalization strategy of electrospun scaffolds enables spatially selective presentation of biological cues

To recapitulate the heterogeneous complexity of tissues in our body with synthetic mimics of the extracellular matrix (ECM), it is important to develop methods that can easily allow the selective functionalization of defined spatial domains. Here, we introduce a facile method to functionalize microfibrillar meshes with different reactive groups able to bind biological moieties in a one-step reaction. The resulting scaffolds proved to selectively support a differential neurite growth after being seeded with dorsal root ganglia. Considering the general principles behind the method developed, this is a promising strategy to realize enhanced biomimicry of native ECM for different regenerative medicine applications.

bioengineering↗

bioRxiv2018

Sodium chloride is an ionic checkpoint for human Th2 cell responses and shapes the atopic skin microenvironment

One sentence summarySodium is an ionic checkpoint for the induction and amplification of human Th2 cell responses and shapes the atopic skin microenvironment, where it could serve as a novel therapeutic target for Th2 mediated diseases.\n\nAbstractThere has been a strong increase in the incidence of allergic diseases over the last 50 years. Environmental factors most likely account for this phenomenon. However, the nature of these factors and the mode of action by which they induce the type 2 immune deviation, which is characteristic of atopic diseases, remains unclear. It has previously been reported that dietary sodium chloride promotes the polarization of Th17 cells with implications for autoimmune diseases such as multiple sclerosis. Here, we demonstrate that sodium chloride also potently promotes Th2 cell responses on multiple regulatory levels. Sodium chloride enhanced IL-4 and IL-13 production while suppressing IFN-{gamma} production in effector T cells. It diverted alternative T cell fates into the Th2 cell phenotype and also induced de novo Th2 cell polarization from naive T cell precursors. Mechanistically, it exerted its effects via the osmosensitive transcription factor NFAT-5 and the kinase SGK-1, which regulated Th2 signature cytokines and master transcription factors in hyperosmolar salt conditions. The skin of patients suffering from atopic dermatitis contained highly elevated amounts of sodium compared to non-lesional atopic and healthy skin. This demonstrates that sodium chloride represents a so far overlooked cutaneous microenvironmental factor in atopic dermatitis that can induce Th2 cell responses, the orchestrators of allergic diseases. Together, our data propose ionic signaling through sodium chloride as a novel checkpoint and potential therapeutic target for type 2 immunity and its associated allergic diseases.

immunology↗