Biology subjects

Schambony, A.

Publications and source records attributed to Schambony, A..

5 recordsLinked to original sources

bioRxiv2025

NCBP2-AS2 is a mitochondrial microprotein, regulates energy metabolism and neurogenesis, and is downregulated in Alzheimer's disease

Microproteins, short functional peptides encoded by small genes, are emerging as critical regulators of cellular processes, yet their roles in mitochondrial function and neurodegeneration remain underexplored. In this study, we identify NCBP2-AS2 as an evolutionarily conserved mitochondrial microprotein with significant roles in energy metabolism and neurogenesis. Using a combination of cellular and molecular approaches, including CRISPR/Cas9 knockout models, stoichiometric co- immunoprecipitation, and advanced imaging techniques, we demonstrate that NCBP2-AS2 localizes to the inner mitochondrial space and interacts with translocase of the inner membrane (TIM) chaperones. These interactions suggest a role in ATPase subunit transport, supported by the observed reductions in ATPase subunit levels and impaired glucose metabolism in NCBP2-AS2-deficient cells. In zebrafish, NCBP2-AS2 knockout led to increased astroglial proliferation, microglial abundance, and enhanced neurogenesis, particularly under amyloid pathology. Notably, we show that NCBP2-AS2 expression is consistently downregulated in human Alzheimers disease brains and zebrafish amyloidosis models, suggesting a conserved role in neurodegenerative pathology. These findings reveal a novel link between mitochondrial protein transport, energy metabolism, and neural regeneration, positioning NCBP2-AS2 as a potential therapeutic target for mitigating mitochondrial dysfunction and promoting neurogenesis in neurodegenerative diseases such as Alzheimers disease.

cell biology↗

bioRxiv2024

Cryogenic light microscopy with Angstrom precision deciphers structural conformations of PIEZO1

Despite the impressive progress in molecular biochemistry and biophysics, many questions regarding the conformational states of large (transmembrane) protein complexes persist. In the case of the PIEZO protein, investigations by cryogenic electron microscopy (Cryo-EM) and atomic force microscopy (AFM) have established a symmetric trimer structure with three long-bladed domains in a propeller-like configuration. A transition of PIEZO protein from curved to flat conformation is hypothesized to actuate closed and open channels for the flow of ions. However, conclusive high-resolution data on the molecular organization of PIEZO in its native form are lacking. To address this shortcoming, we exploit single-particle cryogenic light microscopy (spCryo-LM) to decipher the conformational states of the mouse PIEZO1 protein (mPIEZO1) in the cell membrane. Here, we implement a high-vacuum cryogenic shuttle to transfer shock-frozen unroofed cell membranes in and out of a cryostat for super-resolution microscopy at liquid helium temperature. By localizing fluorescent labels placed at the extremities of the three blades with [A]ngstrom precision, we ascertain three configurations of the protein with radii of 6, 12, and 20 nm as projected onto the membrane plane. Our data suggest that in the smallest configuration, the blades form a nano-dome structure that is more strongly curved than previously observed and predicted by AlphaFold-3. In the largest conformation, we believe the structure must fully unbend in an anticlockwise manner to form a flat extended state. We attribute the 12 nm conformation, the most frequently occupied state, to an intermediate state and discuss our results in the context of the findings from other groups. Combination of spCryo-LM and Cryo-EM measurements together with in situ photothermal stimulation promises to provide quantitative insight into the interplay between structure and function of PIEZO and other biomolecular complexes in their native environments.

biophysics↗

bioRxiv2020

High-precision protein-tracking with interferometric scattering microscopy

The mobility of proteins and lipids within the cell, sculpted oftentimes by the organisation of the membrane, reveals a great wealth of information on the function and interaction of these molecules as well as the membrane itself. Single particle tracking has proven to be a vital tool to study the mobility of individual molecules and unravel details of their behaviour. Interferometric scattering (iSCAT) microscopy is an emerging technique well suited for visualising the diffusion of gold nanoparticle-labelled membrane proteins to a spatial and temporal resolution beyond the means of traditional fluorescent labels. We discuss the applicability of interferometric single particle tracking (iSPT) microscopy to investigate the minutia in the motion of a protein through measurements visualising the mobility of the epidermal growth factor receptor in various biological scenarios on the live cell.

biophysics↗

bioRxiv2018

Interferometric scattering microscopy reveals microsecond nanoscopic protein motion on a live cell membrane

Much of the biological functions of a cell are dictated by the intricate motion of proteins within its membrane over a spatial range of nanometers to tens of micrometers and time intervals of microseconds to minutes. While this rich parameter space is not accessible to fluorescence microscopy, it can be within reach of interferometric scattering (iSCAT) particle tracking. Being sensitive even to single unlabeled proteins, however, iSCAT is easily accompanied by a large speckle-like background, which poses a substantial challenge for its application to cellular imaging. Here, we show that these difficulties can be overcome and demonstrate tracking of transmembrane epidermal growth factor receptors (EGFR) with nanometer precision in all three dimensions at up to microsecond speeds and tens of minutes duration. We provide unprecedented examples of nanoscale motion and confinement in ubiquitous processes such as diffusion in the plasma membrane, transport on filopodia, and endocytosis.

biophysics↗

bioRxiv2017

Connexin43 controls N-cadherin transcription during collective cell migration

Connexins are the primary components of gap junctions, providing direct links between cells in many physiological processes, including cell migration and cancer metastasis. Exactly how cell migration is controlled by gap junctions remains a mystery. To shed light on this, we investigated the role of Connexin43 in collective cell migration during embryo development using the neural crest, an embryonic cell population whose migratory behavior has been likened to cancer invasion. We discovered that Connexin43 is required for contact inhibition of locomotion by directly regulating the transcription of N-cadherin. For this function, the Connexin43 carboxy tail interacts with Basic Transcription Factor 3, which mediates its translocation to the nucleus. Together, they bind to the n-cad promotor regulating n-cad transcription. Thus, we uncover an unexpected, gap junction-independent role for Connexin43 in collective migration that illustrates the possibility that connexins, in general, may be important for a wide variety of cellular processes that we are only beginning to understand.\n\nHighlightsO_LICx43 regulates collective directional migration of neural crest cells\nC_LIO_LICx43 carboxy tail controls cell polarity via n-cad regulation\nC_LIO_LICx43 carboxy tail localises at the nucleus and that depends on BTF3\nC_LIO_LIBTF3 and Cx43 carboxy tail directly interact to bind and regulate n-cad promoter activity\nC_LI

developmental biology↗