Biology subjects

Gentzel, M.

Publications and source records attributed to Gentzel, M..

7 recordsLinked to original sources

bioRxiv2025

EGFL7 promotes immune evasion in glioma through its interaction with integrin β2

Glioblastoma is the most aggressive form of malignant brain cancer, characterized by an immunosuppressive microenvironment and immune evasion. Despite the success of immune checkpoint inhibitors in other cancers, immunotherapies such as anti-PD1 have shown limited efficacy in glioblastoma, underscoring the need to identify tumor-intrinsic mechanisms that sustain this immunosuppressive microenvironment and to develop more effective therapeutic strategies targeting them. Previously, the secreted factor epidermal growth factor-like protein 7 (EGFL7) has been shown to promote brain tumor growth by affecting the glioblastoma microenvironment (GME). However, its impact on the immune system remained enigmatic. Here, we studied the role of EGFL7 in shaping the immune landscape in glioblastoma and identified the underlying molecular mechanisms it engages to drive glioma immune evasion. Single-cell transcriptomic profiling of immune cells derived of glioblastoma revealed that EGFL7 promotes an immunosuppressive GME, characterized by enhanced T cell exhaustion and polarization of macrophages towards a protumorigenic state. Proteomic profiling of EGFL7s interactome in glioma revealed its interaction with integrin {beta}2 (ITGB2), an immune cell surface receptor involved in cell adhesion and migration. Mechanistic studies uncovered the central role of this interaction for immune evasion, which promoted T cell exhaustion and the polarization of macrophages towards a pro-tumorigenic state. Genetic perturbation of the EGFL7-ITGB2 axis attenuated immunosuppression and prolonged the survival of glioblastoma-bearing mice. Remarkably, a combinatorial regimen of anti-EGFL7 and the checkpoint inhibitor anti-PD1 improved the efficacy of this drug, which by itself did not improve glioma patient survival so far. In conclusion, our study provides unequivocal evidence that EGFL7 mediates immune evasion in glioma and has great potential to serve as an add-on drug target to improve immunotherapies not functional in glioblastoma patients so far.

cancer biology↗

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↗

bioRxiv2023

Seeding the meiotic DNA break machinery and initiating recombination on chromosome axes

Programmed DNA double-strand break (DSB) formation is a unique meiotic feature that initiates recombination-mediated linking of homologous chromosomes, thereby enabling chromosome number halving in meiosis. DSBs are generated on chromosome axes by heterooligomeric focal clusters of DSB-factors. Whereas DNA-driven protein condensation is thought to assemble the DSB-machinery, its targeting to chromosome axes is poorly understood. We discovered in mice that efficient biogenesis of DSB-machinery clusters requires seeding by axial IHO1 platforms, which are based on a DBF4-dependent kinase (DDK)-modulated interaction between IHO1 and the chromosomal axis component HORMAD1. IHO1-HORMAD1-mediated seeding of the DSB-machinery on axes ensures sufficiency of DSBs for efficient pairing of homologous chromosomes. Without IHO1-HORMAD1 interaction, residual DSBs depend on ANKRD31, which enhances both the seeding and the growth of DSB-machinery clusters. Thus, recombination initiation is ensured by complementary pathways that differentially support seeding and growth of DSB-machinery clusters, thereby synergistically enabling DSB-machinery condensation on chromosomal axes.

cell biology↗

bioRxiv2021

Shedding light on biosilica morphogenesis by comparative analysis of the silica-associated proteomes from three diatom species

O_LIMorphogenesis of the intricate patterns of diatom silica cell walls is a protein-guided process, yet to date only very few such silica morphogenetic proteins have been identified. Therefore, it is unknown whether all diatoms share conserved proteins of a basal silica forming machinery, and whether unique proteins are responsible for the morphogenesis of species specific silica patterns. C_LIO_LITo answer these questions, we extracted proteins from the silica of three diatom species (Thalassiosira pseudonana, Thalassiosira oceanica and Cyclotella cryptica) by complete demineralization of the cell walls. LC-MS/MS analysis of the extracts identified 92 proteins that we name Soluble Silicome Proteins (SSPs). C_LIO_LISurprisingly, no SSPs are common to all three species, and most SSPs showed very low similarity to one another in sequence alignments. In depth bioinformatics analyses revealed that SSPs can be grouped into distinct classes bases on short unconventional sequence motifs whose functions are yet unknown. The results from in vivo localization of selected SSPs indicates that proteins, which lack sequence homology but share unconventional sequence motifs may exert similar functions in the morphogenesis of the diatom silica cell wall. C_LI

molecular biology↗

bioRxiv2019

Allosteric structural alterations and auto-regulation of Rab5 GEF activity in Rabex5

Intracellular trafficking depends on the function of Rab GTPases, whose activation is regulated by guanine exchange factors (GEFs). The Rab5 GEF, Rabex5, was previously proposed to be autoinhibited by its C-terminus. Here, we studied full-length Rabex5 and Rabaptin5 proteins as well as domain deletion Rabex5 mutants using hydrogen deuterium exchange mass spectrometry. We generated a structural model of Rabex5, using chemical crosslinking mass spectrometry and integrative modeling techniques. Our results are inconsistent with the previous model of autoinhibition. By correlating structural changes with nucleotide exchange activity for each construct, we uncovered new auto-regulatory roles for the Ubiquitin binding domains and the Linker connecting those domains to the catalytic core of Rabex5. Our results suggest a more complex auto-regulation mechanism than previously thought and imply that Ubiquitin binding serves not only to position Rabex5 but to also control its Rab5 GEF activity through allosteric structural alterations.

biophysics↗

bioRxiv2017

MS Western, a method of multiplexed absolute protein quantification is a practical alternative to western blotting

Absolute quantification of proteins elucidates the molecular composition, regulation and dynamics of multiprotein assemblies and networks. Here we report on a method termed MS Western that accurately determines the molar abundance of dozens of user-selected proteins at the sub-femtomole level in whole cell or tissue lysates without metabolic or chemical labelling and without using specific antibodies. MS Western relies upon GeLC-MS/MS and quantifies proteins by in-gel co-digestion with an isotopically labelled QconCAT protein chimera composed of concatenated proteotypic peptides. It requires no purification of the chimera and relates the molar abundance of all proteotypic peptides to a single reference protein. In comparative experiments, MS Western outperformed immunofluorescence Western blotting by the protein detection specificity, linear dynamic range and sensitivity of protein quantification. To validate MS Western in an in vivo experiment, we quantified the molar content of zebrafish core histones H2A, H2B, H3 and H4 during ten stages of early embryogenesis. Accurate quantification (CV<10%) corroborated the anticipated histones equimolar stoichiometry and revealed an unexpected trend in their total abundance.

biochemistry↗

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↗