Biology subjects

Mann, F.

Publications and source records attributed to Mann, F..

8 recordsLinked to original sources

bioRxiv2025

Neural function of Netrin-1 in precancerous lesions of the pancreas

The nervous system undergoes dynamic structural remodeling to infiltrate cancerous tumors, contributing to their growth and progression. Emerging evidence indicates that neuroplasticity initiates early, with nerve terminals detecting and responding to tissue changes even during precancerous stages. Notably, dense sympathetic axon sprouting has been observed around pancreatic intraepithelial neoplasia (PanIN), a common precursor lesion to pancreatic cancer. However, the molecular signals driving this early neuroplasticity and its functional consequences remain poorly understood. Here, we identify the axon guidance molecule Netrin-1 as a key factor secreted by pancreatic cells within precursor lesions of pancreatic cancer. Netrin-1 promotes sympathetic axon growth and branching through its receptor, Deleted in Colorectal Cancer (DCC). Inhibition of Netrin-1 disrupts sympathetic axon remodeling while accelerating PanIN formation and progression, driven by increased precancerous cell proliferation. Furthermore, human pancreatic tissue analysis corroborates Netrin-1 expression in precursor lesions. These findings suggest that Netrin-1-driven sympathetic neuroplasticity plays a protective role in the precancerous microenvironment by modulating local cellular dynamics, providing new insights into early cancer progression.

cancer biology↗

bioRxiv2023

Pancreatic Schwann cell reprogramming supports cancer-associated neuronal remodeling

The peripheral nervous system is a key regulator of cancer progression. In pancreatic ductal adenocarcinoma (PDAC), the sympathetic branch of the autonomic nervous system inhibits cancer development. This inhibition is associated with extensive sympathetic nerve sprouting in early pancreatic cancer precursor lesions. However, the underlying mechanisms behind this process remain unclear. This study aimed to investigate the roles of pancreatic Schwann cells in the structural plasticity of sympathetic neurons. We examined the changes in the number and distribution of Schwann cells in a transgenic mouse model of PDAC and in a model of metaplastic pancreatic lesions induced by chronic inflammation. Schwann cells proliferated and expanded simultaneously with new sympathetic nerve sprouts in metaplastic/neoplastic pancreatic lesions. Sparse genetic labeling showed that individual Schwann cells in these lesions had a more elongated and branched structure than those under physiological conditions. Schwann cells overexpressed proinflammatory and neurotrophic factors, including glial cell-derived neurotrophic factor (GDNF). Sympathetic neurons upregulated the GDNF receptor and promoted cell growth in response to GDNF in vitro. Selective genetic deletion of Gdnf in Schwann cells completely blocked sympathetic nerve sprouting in metaplastic pancreatic lesions in vivo. This study demonstrated that pancreatic Schwann cells underwent adaptive reprogramming during early cancer development, supporting a protective antitumor neuronal response. These finding could help to develop new strategies to modulate cancer associated neural plasticity. MAIN POINTSO_LINon-myelinating pancreatic Schwann cells associate with sympathetic axon terminals supplying the pancreas. C_LIO_LIPancreatic Schwann cells proliferate and undergo adaptive reprogramming in response to chronic inflammation and the development of pancreatic cancer. C_LIO_LIGlial cell line-derived neurotrophic factor expression in reprogrammed pancreatic Schwann cells promotes Schwann cell expansion and sympathetic axon sprouting in pancreatic cancer precursor lesions. C_LI

neuroscience↗

bioRxiv2023

Neuronal miR-17-5p contributes to interhemispheric cortical connectivity defects induced by prenatal alcohol exposure

Prenatal alcohol exposure (PAE) is the leading cause of non-genetic intellectual disabilities in the Western world and is responsible of a wide spectrum of neurodevelopmental disorders referred to as Fetal Alcohol Spectrum Disorders (FASD). Structural and functional deficits in brain connectivity have been reported in FASD patients; still, whether and how PAE affects the axonal development of neurons and disrupts the wiring between brain regions is not known. Here, we developed a mouse model of moderate alcohol exposure during prenatal brain wiring to study the impact of PAE on corpus callosum (CC) development, a major white matter tract reported to be affected in FASD patients. Our results show that PAE induces aberrant navigation of interhemispheric CC axons that persist even after the end of the exposure, causing their ectopic termination in the contralateral cortex. Furthermore, these defects in interhemispheric connectivity persist into adulthood and are associated with defective bilateral sensorimotor coordination in behavioral tasks requiring cortical control and interhemispheric communication. Finally, we identified neuronal miR-17-5p and its target Ephrin type A receptor 4 (EphA4) as mediators of the effect of alcohol on the contralateral targeting of CC axons. Taken together, our results suggest that alteration of miRNA-mediated regulation of axon guidance signaling by prenatal alcohol exposure affects interhemispheric cortical connectivity and associated behavior in FASD.

neuroscience↗

bioRxiv2021

A fluorescent nanosensor paint reveals the heterogeneity of dopamine release from neurons at individual release sites

The neurotransmitter dopamine is released from discrete axonal structures called varicosities. Its release is essential in behaviour and is critically implicated in prevalent neuropsychiatric diseases. Existing dopamine detection methods are not able to detect and distinguish discrete dopamine release events from multiple varicosities. This prevents an understanding of how dopamine release is regulated across populations of discrete varicosities. Using a near infrared fluorescent (980 nm) dopamine nanosensor paint (AndromeDA), we show that action potential-evoked dopamine release is highly heterogeneous across release sites and also requires molecular priming. Using AndromeDA, we visualize dopamine release at up to 100 dopaminergic varicosities simultaneously within a single imaging field with high temporal resolution (15 images/s). We find that hotspots of dopamine release are highly heterogeneous and are detected at only ~17% of all varicosities. In neurons lacking Munc13 proteins, which prime synaptic vesicles, dopamine release is abolished during electrical stimulation, demonstrating that dopamine release requires vesicle priming. In summary, AndromeDA reveals the spatiotemporal organization of dopamine release.

neuroscience↗

bioRxiv2020

Sympathetic axonal sprouting induces changes in macrophage populations and protects against pancreatic cancer

Recent evidence has highlighted the presence of neuronal nerve processes in the tumor microenvironment. However, the origin of intra-tumoral nerves remains poorly known, in part because of technical difficulties in tracing nerve fibers via regular histological preparations. Here, we employed three-dimensional (3D) imaging of cleared tissues for a comprehensive analysis of sympathetic innervation in pancreatic ductal adenocarcinoma (PDAC). The results support two independent, but coexisting, mechanisms: passive engulfment of pre-existing nerves within tumors and active, localized sprouting of nerve terminals into non-neoplastic lesions and tumor periphery. Nerve ablation revealed an inverse correlation between sympathetic innervation and tumor growth and spread. Furthermore, sympathectomy increased CD163+ macrophage levels, which contributed to worse outcomes. Altogether, our findings revealed protective properties of the sympathetic nervous system in PDAC immunity and progression that could pave the way for new treatments.

cancer biology↗

bioRxiv2019

Programmed transport and release of nanoscale cargo by immune cells

Transport and delivery of (nanoscale) materials are crucial for many applications in biomedicine. However, controlled uptake, transport and triggered release of such cargo remains challenging. In this study, we use human immune cells (neutrophilic granulocytes, neutrophils) and program them to perform these tasks in vitro. For this purpose, we let neutrophils phagocytose a nanoscale cargo. As an example, we used DNA-functionalized single-walled carbon nanotubes (SWCNT) that fluoresce in the near infrared (980 nm) and serve as sensors for small molecules. Cells still migrate, follow chemical gradients and respond to inflammatory signals after uptake of the cargo. To program release, we make use of neutrophil extracellular trap formation (NETosis), a novel cell death mechanism that leads to chromatin swelling and subsequent rupture of the cellular membrane and release of the cells whole content. By using the process of NETosis we can program the time point of cargo release via the initial concentration of stimuli such as phorbol 12-myristate-13-acetate (PMA) or lipopolysaccharide (LPS). At intermediate stimulation with LPS (100 g/ml), cells continue to migrate, follow gradients and surface cues for around 30 minutes and up to several hundred micrometers until they stop and release their cargo. The transported and released SWCNT sensor cargo is still functional as shown by subsequent detection of the neurotransmitter dopamine and reactive oxygen species (H2O2). In summary, we hijack a biological process (NETosis) and demonstrate how neutrophils can be used for programmed transport and delivery of functional nanomaterials.

biophysics↗

bioRxiv2019

Subthreshold psychosis symptoms associated with molecular genetic risk in a population-based cohort: Findings from Generation Scotland

ImportanceSubthreshold psychosis symptoms in the general population may be associated with genetic risk for schizophrenia. In this analysis, empirically-derived symptom factor scores led to a detection of significant and robust polygenic signal.\n\nObjectiveThis study sought to optimize genetic association with data-driven symptom factor scores, accounting for cohort factor structure and sex differences.\n\nDesignEFA-derived symptom factor scores were regressed onto PRS for schizophrenia in models accounting for age and genetic ancestry principal components. Follow-up examination of symptom factor score associations with other related genetic risks included ADHD, autism, bipolar disorder, major depression, and neuroticism.\n\nParticipantsThis study examined the newly expanded symptom dataset from the Northern European ancestry cohort, Generation Scotland: Scottish Family Health Study (N = 9,105 individuals 18-65 years of age) comprising common variant and subthreshold psychosis symptom data. A total of 5,391 females and 3,713 males with age M[SD] = 45.2 [13] were included in the final analyses.\n\nMain Outcome and MeasureSubthreshold psychosis symptoms were measured using the Schizotypal Personality Questionnaire-Brief (SPQ-B). Primary phenotypic factor scores and genome-wide polygenic risk scores (PRS) reflected weighted sum scores and were examined as continuous measures. Polygenic risk scores were calculated from genome-wide association summary statistics using 7,358,674 imputed common genetic variants passing quality control.\n\nResultsIn males, symptom factor scores were positively associated with polygenic risk for schizophrenia alone and implicated primarily interpersonal/negative symptoms. In females, symptom factor scores were positively associated with polygenic risks for ADHD and autism but not schizophrenia. Scores were robustly associated with genetic risk for neuroticism across both males and females.\n\nConclusions and RelevanceThis study detected a significant association of subthreshold psychosis symptoms with genetic risk for schizophrenia and neuroticism in a population-based sample. Furthermore, important sex differences suggest a need for better understanding of schizophrenia risk assessment in females.\n\nKey PointsO_ST_ABSQuestionC_ST_ABSWhat molecular genetic risks are associated with subthreshold psychosis symptoms in the general population?\n\nFindingsIn a large population-based cohort (N = 9,084), significant associations of polygenic risks with symptoms were observed. Symptoms were associated with genetic risk for schizophrenia in males, for ADHD and autism spectrum disorder in females, and for neuroticism across both males and females.\n\nMeaningAssociations of genetic risk with symptoms in the general population are highly significant and suggest important sex differences.

genetics↗

bioRxiv2019

Exfoliated near infrared fluorescent CaCuSi4O10 nanosheets with ultra-high photostability and brightness for biological imaging

Imaging of complex (biological) samples in the near infrared (nIR) range of the spectrum is beneficial due to reduced light scattering, absorption, phototoxicity and autofluorescence. However, there are only few near infrared fluorescent materials known and suitable for biomedical applications. Here, we exfoliate the layered pigment CaCuSi4O10 (known as Egyptian Blue, EB) via facile tip sonication into nanosheets (EB-NS) with ultra-high nIR fluorescence stability and brightness. The size of EB-NS can be tailored by tip sonication to diameters < 20 nm and heights down to 1 nm. EB-NS fluoresce at 910 nm and the total fluorescence intensity scales with the number of Cu2+ ions that serve as luminescent centers. Furthermore, EB-NS display no bleaching and ultra-high brightness compared to other nIR fluorophores. The versatility of EB-NS is demonstrated by in vivo single-particle tracking and microrheology measurements in developing Drosophila embryos. Additionally, we show that EB-NS can be uptaken by plants and remotely detected in a low cost stand-off detection setup despite strong plant background fluorescence. In summary, EB-NS are a highly versatile, bright, photostable and biocompatible nIR fluorescent material that has the potential for a wide range of bioimaging applications both in animal and plant systems.

biophysics↗