Biology subjects

Jung, E.

Publications and source records attributed to Jung, E..

24 records · Page 2Linked to original sources

bioRxiv2021

A connectivity signature for glioblastoma

Tumor cell extensions called tumor microtubes (TMs) in glioma resemble neurites during neurodevelopment and connect glioma cells to a network that has considerable relevance for tumor progression and therapy resistance. The determination of interconnectivity in individual tumors has been challenging and the impact of tumor cell connectivity on patient survival remained unresolved so far. Here, a connectivity signature from single-cell RNA-sequenced (scRNA-Seq) xenografted primary glioblastoma (GB) cells was established and clinically validated. Thirty-four of 40 connectivity genes were related to neurogenesis, neural tube development or glioma progression, including the TM-network-relevant GAP43 gene. Astrocytic-like and mesenchymal-like GB cells had the highest connectivity signature scores in scRNA-Seq data of patient-derived xenografts and patient samples. In 230 human GBs, high connectivity correlated with the mesenchymal expression subtype, TP53 wildtype, and with dismal patient survival. CHI3L1 was identified as a robust molecular marker of connectivity. Thus, the connectivity signature allows novel insights into brain tumor biology, provides a proof-of-principle that tumor cell connectivity is relevant for patients prognosis, and serves as a robust biomarker that can be used for future clinical trials. Statement of significanceIntegration of GB cells into functional networks drives tumor progression and resistance. Here, we established and validated a novel connectivity gene expression signature of single GB cells and whole tumors that can be easily applied to clinical and preclinical samples. It is shown that connectivity is determining prognosis combining molecular, functional and clinical insights into the disease.

cancer biology↗

bioRxiv2021

Rapid Directed Molecular Evolution of Fluorescent Proteins in Mammalian Cells

In vivo imaging of model organisms is heavily reliant on fluorescent proteins with high intracellular brightness. Here we describe a practical method for rapid optimization of fluorescent proteins via directed molecular evolution in cultured mammalian cells. Using this method, we were able to perform screening of large gene libraries containing up to 2{middle dot}107 independent random genes of fluorescent proteins expressed in HEK cells completing one iteration directed evolution in a course of [~]8 days. We employed this approach to develop a set of green and near-infrared fluorescent proteins with enhanced intracellular brightness. The developed near-infrared fluorescent proteins demonstrated high performance for fluorescent labeling of neurons in culture and in vivo in model organisms such as C.elegans, Drosophila, zebrafish, and mice. Spectral properties of the optimized near-infrared fluorescent proteins enabled crosstalk-free multicolor imaging in combination with common green and red fluorescent proteins, as well as dual-color near-infrared fluorescence imaging. The described method has a great potential to be adopted by protein engineers due to its simplicity and practicality. We also believe that the new enhanced fluorescent proteins will find wide application for in vivo multicolor imaging of small model organisms.

molecular biology↗

bioRxiv2020

Gated feedforward inhibition in the frontal cortex releases goal-directed action

Cortical circuits process sensory information and generate motor signals in animals performing perceptual tasks. However, it is still unclear how sensory inputs generate motor signals in the cortex to initiate goal-directed action. Here, we identified a visual-to-motor inhibitory circuit in the anterior cingulate cortex (ACC) that induced action initiation in mice performing visual Go/No-go tasks. Interestingly, higher activity in sensory neurons and faster suppression in motor neurons of the ACC predicted faster reaction times. Notably, optogenetic activation of visual inputs in the ACC evoked strong suppression of neighboring motor neurons by activating fast-spiking sensory neurons and drove task-relevant actions in mice via activating striatal neurons. Finally, the ACC network activity maintained low during spontaneous and perceptual actions and increased during action cancellation in response to the stop signals. Collectively, our data demonstrate that visual salience in the frontal cortex exerts gated feedforward inhibition to release goal-directed actions.

neuroscience↗

bioRxiv2020

CDC50A dependent phosphatidylserine exposure induces inhibitory post-synapse elimination by microglia

Glia contribute to synapse elimination through phagocytosis in the central nervous system. Despite important roles during development and neurological disorders, the "eat-me" signal that initiates glia-mediated phagocytosis of synapses remains largely elusive. Here, by generating inducible conditional knockout mice of Cdc50a, we induced stable exposure of phosphatidylserine in the neuronal outer membrane. Surprisingly, acute Cdc50a deletion in neurons causes specific loss of inhibitory post-synapses without affecting other synapses, thereby generating excessive excitability with appearance of seizure. Ablating microglia or deleting microglial Mertk rescues the loss of inhibitory post-synapses, indicating that microglial phagocytosis is responsible for inhibitory post-synapse elimination. Moreover, inhibitory post-synapses in normal juvenile brains also use phosphatidylserine for synapse pruning by microglia, suggesting that phosphatidylserine may serve as a general "eat-me" signal for inhibitory post-synapse elimination. One Sentence SummaryCdc50a dependent phosphatidylserine exposure functions as an "eat-me" signal for microglia-dependent inhibitory post-synapse elimination

neuroscience↗

bioRxiv2020

Tumor-infiltrating nerves create an electro-physiologically active microenvironment and contribute to treatment resistance

Patients with densely innervated tumors do poorly as compared to those with sparsely innervated disease. Why some tumors heavily recruit nerves while others do not, remains unknown as does the functional contribution of tumor-infiltrating nerves to cancer. Moreover, while patients receive chemotherapeutic treatment, whether these drugs affect nerve recruitment has not been tested. Using a murine model of ovarian cancer, we show that tumor-infiltrating sensory nerves potentiate tumor growth, decrease survival, and contribute to treatment resistance. Furthermore, matched patient samples show significantly increased tumor innervation following chemotherapy. In vitro analysis of tumor-released extracellular vesicles (sEVs) shows they harbor neurite outgrowth activity. These data suggest that chemotherapy may alter sEV cargo, endowing it with robust nerve recruiting capacity.

cancer biology↗

bioRxiv2019

Organogenesis and Distribution of the Ocular Lymphatic Vessels in the Anterior Eye: Implication to Glaucoma Surgery Site Selection

Glaucoma surgeries, such as trabeculectomy, are performed to lower the intraocular pressure to reduce the risk of vision loss. The surgeries create a new passage in the eye that reroutes the aqueous humor outflow to the subconjunctival space, where the fluid is presumably absorbed by the conjunctival lymphatics. However, the current knowledge of these ocular surface lymphatics remains limited. Here, we characterized the biology and function of the ocular lymphatics using transgenic lymphatic reporter mice and rats. We found that the limbal and conjunctival lymphatic networks are progressively formed by a primary lymphatic vessel that grows out from the nasal-side medial canthus region at the time of birth. This primary lymphatic vessel immediately branches out and invades the limbus and conjunctiva, and then simultaneously encircles the cornea in a bidirectional manner. As a result, the distribution of the ocular lymphatic is significantly polarized toward the nasal side, and the limbal lymphatics are directly connected to the conjunctival lymphatics. New lymphatic spouts are mainly produced from the nasal-side limbal lymphatics, posing the nasal side of the eye more responsive to fluid drainage and inflammatory stimuli. Consistently, when a fluorescent tracer was injected, fluid clearance was much more efficient in the nasal side than the temporal side of the eyes. In comparison, blood vessels are evenly distributed on the front surface of the eyes. We found that these distinct vascular distribution patterns were also conserved in human eyes. Together, our study demonstrated that the ocular surface lymphatics are more densely present in the nasal side and uncovered the potential clinical benefits in selecting the nasal side as a surgical site for glaucoma surgeries to improve the fluid drainage.

developmental biology↗