Biology subjects

Renz, M.

Publications and source records attributed to Renz, M..

3 recordsLinked to original sources

bioRxiv2023

Repeated FRAP of the actin-binding protein CapG in the cell nucleus - a functional assay for EGF signaling in the single live breast cancer cell

Compartmentalization and differential distribution of proteins within a cell maintain cellular function and viability. CapG is the only gelsolin-related actin-binding protein that distributes in steady state diffusively throughout cytoplasm and cell nucleus. To detect changes in CapGs nuclear shuttling in response to external stimuli on the single cell level, we established repeated FRAP experiments of one and the same breast cancer cell. With this experimental set up, we found that ATP-depletion reversibly decreased CapGs shuttling into the cell nucleus. The addition of epidermal growth factor (EGF) increased CapGs nuclear shuttling within minutes. Serum-starvation doubled the number of breast cancer cells from 40% to 80% displaying increased CapG shuttling in response to EGF. Testing five different potential CapG phosphorylation sites, we found that serine 70 mediates the increase in CapGs nuclear shuttling triggered by EGF. Thus, repeated FRAP of CapG in the cell nucleus can be used as functional readout of signaling cascades in the same single live breast cancer cell.

cancer biology↗

bioRxiv2022

Thirty years of deforestation within the entire ranges of nine endangered lemur species (3 CR, 4 EN, 2 VU) in northwestern Madagascar

Forest cover change is of particular concern in tropical regions. In this study, we investigate the degree of deforestation in the entire ranges of nine highly threatened lemur species in northwestern Madagascar. Landsat satellite images were acquired from four different time stages (1990, 2000, 2011, 2020), classified into forest/non-forest, and changes quantified. Forest cover declined from 17.5% to 9.3% within the last 30 years. This decline varied across four protected areas (PAs) investigated: the forest cover of Ankarafantsika National Park (ANP) declined only moderately over time (from 76.3% to 67.4%), while it declined drastically in other PAs (e.g., from 54.9% to 18.9%, Bongolava Forest Corridor). Two lemur taxa are most affected (Lepilemur otto, Microcebus bongolavensis) by having only very few isolated forest patches left within their ranges (approximately 542.7 km{superscript 2}). For two other species (L. ahmansoni, L. aeeclis), most of the remaining forest is concentrated in two coastal PAs (in total 627.2 and 477.9 km{superscript 2}, respectively), while those species occurring inside ANP (5 taxa) experienced rather stable forest coverage until 2020. A reversal of these deforestation trends and active reforestation measures are desperately needed to reduce habitat loss for these nine lemur species. A practical experience-based guideline is therefore provided.

ecology↗

bioRxiv2018

Cytoplasmic self-organization established by internal lipid membranes in the interplay with either actin or microtubules

Cells harbor an intrinsic organization of their components. Specific protein structures, as the centrosome, have been described master regulators of cell organization. In the absence of these key elements, however, cytoplasmic selforganization has nevertheless been observed. Cytoplasmic self-organization was postulated to arise from the interaction of microtubules with molecular motors on lipid membrane surfaces.\n\nHere, we show that lipid membranes are capable of organizing both major cytoskeletal systems, microtubules and actin, even if one or the other cytoskeletal system is completely paralyzed. A microfluidic droplet system and Xenopus oocyte extracts enabled us to build an artificial cell and study minimal requirements for cellular self-organization. Mathematical modeling reveals the interaction of lipid membranes with any filament system through molecular motors as a universal principle of cytoplasmic self-organization. Both cytoskeletal systems form mechanisms to establish robust 2-dimensional selforganization and self-centering. Pharmacologic inhibition of the cytoskeletal network systems helps dissect specific contributions of each network in the interplay with lipid membranes with regards to 2- and 3-dimensional organization, time and length scale of cytoplasmic organization and the degree of concentration of the centered elements. While microtubules provide 3-dimensional polarity, actin filaments ensure fast and dense compaction and long-range organization.

cell biology↗