Biology subjects

Kersten, N.

Publications and source records attributed to Kersten, N..

7 recordsLinked to original sources

bioRxiv2026

Spatiotemporal proteomics elucidates trafficking and localization of Neuroligins to the axon initial segment plasma membrane

Neuronal development and function rely on precise sorting of membrane proteins to distinct neuronal domains, yet the underlying mechanisms remain incompletely understood. Here, we investigated the trafficking of two highly homologous NLGNs (NLGN1 and 2) which distinctly localize and function at excitatory and inhibitory synapses. By using spatiotemporal proteomics, genetic engineering and microscopy in CNS cultured neurons and organotypic slices, we dissected the itinerary of biosynthetic NLGNs, identifying co-cargoes and sorting routes to dendrites and the AIS. At the AIS, which contains only inhibitory synapses, both NLGN1 and NLGN2 are locally exocytosed. While NLGN2 is stably recruited to axo-axonic synapses by its extracellular domain and modulated by activity, NLGN1 is retrieved by endocytic mechanisms. We propose that biosynthetic NLGNs are co-sorted to the AIS PM where they detect pre-synaptic type. These findings may help to elucidate the role of AIS-localized NLGNs in shaping AIS structural and functional plasticity. HighlightsO_LISpatiotemporal proteomics elucidates interactome of biosynthetic NLGN1 in neurons C_LIO_LINLGN1 and NLGN2 are targeted to the AIS by kinesin-1 C_LIO_LINLGN2, but not NLGN1, is retained at axo-axonic synapses and modulated by activity C_LIO_LINLGN stability at the AIS plasma membrane is determined by the ectodomain C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=194 HEIGHT=200 SRC="FIGDIR/small/733123v1_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@a45909org.highwire.dtl.DTLVardef@1d171b0org.highwire.dtl.DTLVardef@17f132aorg.highwire.dtl.DTLVardef@1c33a8d_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2026

Calsyntenin-1 and calsyntenin-3 coordinate TGN exit of axonal cargoes

Neurons rely on precise biosynthetic protein transport from the soma to the axon and dendrites. Brain-enriched calsyntenins (CSTN1-3) are unique transmembrane adaptors that link cargo to kinesin-1 for transport. Yet, the neuronal distribution and interdependence of the three CSTN paralogs remain unclear. Here, we dissected their subcellular localization and contribution to biosynthetic protein transport. CSTN paralogs were predominantly localized to the TGN and axonal vesicles, with CSTN1 and CSTN3 showing higher expression levels than CSTN2. Depletion of either CSTN1 or CSTN3 affected axonal abundance of the other, suggesting that they function within the same pathway. Consistently, knockdown of CSTN1 or CSTN3, but not CSTN2, impaired the TGN exit and transport of multiple biosynthetic cargoes to the axon. Interestingly, most CSTN-positive vesicles exiting the TGN and in the axon were marked by the biosynthetic trafficking regulator RAB6A. Furthermore, we identified opposing, paralog-specific roles of CSTN1 and CSTN3 in regulating RAB6A levels at the TGN, thereby contributing to Golgi organization and axonal trafficking. Loss of CSTN1 reduced RAB6A and induced Golgi compaction, whereas loss of CSTN3 increased RAB6A and promoted Golgi dispersal. Together, we reveal that CSTN1 and CSTN3 have distinct, yet intersecting roles in the regulation of biosynthetic axonal transport.

Cell Biology↗

bioRxiv2025

The axonal ER couples translation and secretion machineries for local delivery of axonal transmembrane proteins to promote axonal development

Neuronal development and function rely on the polarized sorting of transmembrane proteins (TMPs). Most TMPs follow a conventional secretory pathway confined to the cell soma, where ER-translated TMPs exit the ER through ERES to reach the Golgi, prior to PM delivery. We recently found that the axonal ER regulates local translation; however, how this is linked to secretion remains unknown. Here, we find that axonally translated TMPs exit the ER and reach the axonal PM via an ERES-dependent/Golgi-independent route. Intriguingly, we uncover a feedback loop linking translation and secretion at axonal ERES. HDLBP-dependent TMP synthesis regulates ERES formation, and axonal ERES in turn modulate TMP translation. Subsequently, the NRZ-SEC22B tethering complex links local TMP ER exit to PM delivery, dependent on ER-PM contacts. Axonal ERES and these associated molecular players support axon growth and bouton assembly. We propose a novel mechanism in which coupling of axonal TMP synthesis and secretion is essential for neuronal development.

cell biology↗

bioRxiv2025

The microcephaly-associated protein YIPF5 differentially regulates ER-export

YIPF5 is a small ER-membrane protein implicated in ER-Golgi transport. Mutations in YIPF5 cause MEDS2 (microcephaly with simplified gyral pattern, epilepsy, and neonatal diabetes syndrome), a fatal disorder manifesting in early childhood. We demonstrate that YIPF5 is involved in ER export of a subset of proteins, including cargoes of the ER-export receptor SURF4, with which it directly interacts. In YIPF5 knockout cells, we observe a shift in the cell surface and secretome composition, marked by reduced neuronal adhesion molecules and increased secretion of ER chaperones influencing cell migration. YIPF5 depletion enhances cell migration in a wound-healing assay and alters SURF4 localization, causing elongated ERGIC53- and Rab1-positive tubules from COPII-labeled ER exit sites. Kinetic analysis suggests that YIPF5 negatively regulates SURF4-mediated ER export. In utero knockdown of Yipf5 in embryonic mouse brains induces premature neuronal migration and abnormal neuronal morphology. These findings suggest that YIPF5 and SURF4 coordinate ER export, and disruption may underlie cortical development defects leading to microcephaly.

cell biology↗

bioRxiv2024

Spatiotemporal proteomics reveals the biosynthetic lysosomal membrane protein interactome in neurons

Lysosomes are membrane-bound organelles critical for maintaining cellular homeostasis. Delivery of biosynthetic lysosomal proteins to lysosomes is crucial to orchestrate proper lysosomal function. However, it remains unknown how the delivery of biosynthetic lysosomal proteins to lysosomes is ensured in neurons, which are highly polarized cells. Here, we developed Protein Origin, Trafficking And Targeting to Organelle Mapping (POTATOMap), by combining trafficking synchronization and proximity-labelling based proteomics, to unravel the trafficking routes and interactome of the biosynthetic lysosomal membrane protein LAMP1 at specified time points. This approach, combined with advanced microscopy, enabled us to identify the neuronal domain-specific trafficking machineries of biosynthetic LAMP1. We revealed a role in replenishing axonal lysosomes, in delivery of newly synthesized axonal synaptic proteins, and interactions with RNA granules to facilitate hitchhiking in the axon. POTATOMap offers a robust approach to map out dynamic biosynthetic protein trafficking and interactome from their origin to destination.

cell biology↗

bioRxiv2022

Multi-view confounder detection for biomedical studies

In many biomedical studies an important first step is checking for confounding factors. For association studies, confounding can for example be caused by ethnic differences in the case and control groups. In many other settings there might be confounding factors like batch effects or founder effects that also need to be detected and controlled for1. Detecting confounding for data from one data source is well established (e.g., genomics data). Since more and more studies are now based on data from multiple data modalities (e.g., multi-omics), we evaluated whether multi-view confounder detection can benefit from state-of-the-art methods for multi-view data integration. Especially for clustering of multi-omics data, it has been shown that these methods can perform better than methods that treat the data modalities separately2. Our results show that multi-view confounder analysis is possible and that building on multi-view data integration methods is better than treating the different data modalities separately.

bioinformatics↗

bioRxiv2022

Protein profiling of breast carcinomas reveals expression of immune-suppressive factors and signatures relevant to patient outcome

BackgroundIn cancerous tissue, a complex interplay of tumour cells with different cell types from the tumour microenvironment is causing modulations in signalling processes. By directly assessing expression of a multitude of proteins and protein variants, extensive information on signalling pathways, their activation status and the effect of the immunological landscape can be obtained providing viable information for treatment response. MethodsProtein extracted from archived breast cancer tissue from patients without adjuvant therapy was subjected to high-throughput Western blotting using the DigiWest technology. Expression of 150 proteins and protein variants covering cell cycle control, apoptosis, Jak/Stat, MAPK-, Pi3K/Akt-, Wnt-, and, autophagic signalling as well as general tumour markers was monitored in a cohort of 84 patient samples. The degree of immune cell infiltration was investigated and set against treatment outcome by integrating patient specific follow-up data. ResultsCharacterization of the tumour microenvironment by monitoring CD8, CD11c, CD16 and CD68 expression revealed a strong correlation of event-free patient survival with immune cell infiltration. Furthermore, the presence of tumour infiltrating lymphocytes was linked to a pronounced activation of the Jak/Stat signalling pathway and apoptotic processes. Elevated phosphorylation of peroxisome proliferator-activated receptor gamma (PPAR{gamma}, pS112) in non-immune infiltrated tumour tissue suggests a novel immune evasion mechanism in breast cancer characterized by increased PPAR{gamma} activation. ConclusionMultiplexed immune cell marker assessment and protein profiling of tumour tissue provides functional signalling data facilitating breast cancer patient stratification.

cancer biology↗