Biology subjects

Zehrer, A.

Publications and source records attributed to Zehrer, A..

2 recordsLinked to original sources

bioRxiv2025

Mutations in VPS18 lead to a neutrophil maturation defect associated with disturbed vesicle homeostasis

Neutrophils, the first cells to arrive at the site of inflammation, are rather short-lived cells and thus have to be constantly replenished. During neutrophil development, vesicle dynamics need to be fine-tuned and impaired vesicle trafficking has been linked to failure in neutrophil maturation. Here, we characterized the role of VPS18 as a central core component of CORVET & HOPS tethering complexes for neutrophil development. Using CRISPR/Cas9-engineered Hoxb8 cells with heterozygous mutations in Vps18, we found that VPS18 deficiency interfered with neutrophil development due to tethering complex instability. As a result, vesicle dynamics were impaired with a strong increase in LC3-II and p62 levels, indicating autophagosome accumulation and reduced autophagic flux. With transmission electron microscopy, we verified the increase in autophagosomes and also found irregularly shaped vesicular structures in Vps18 mutants. Subsequently, Vps18 mutant neutrophil progenitors underwent premature apoptosis. We described a novel patient with a heterozygous stop-gain mutation in VPS18 suffering from neutropenia and recurrent infections. To verify our findings in the human system, we used human induced pluripotent stem cells (iPSCs). Upon differentiation into neutrophils, loss of VPS18 resulted in an almost complete absence of iPSC-derived developing neutrophils. Heterozygous VPS18 mutant and patient mutation-harboring iPSCs were characterized by strongly reduced numbers of developing neutrophils. Zebrafish larvae with heterozygous mutations in vps18 were also characterized by significantly reduced neutrophil numbers. This study shows the pivotal impact of VPS18 for adequate vesicle dynamics during neutrophil development which might be relevant in the context of vesicle trafficking during granulopoiesis and congenital neutropenia.

physiology↗

bioRxiv2025

SCAMP3 is essential for proper formation and function of neutrophil granules

Host defense functions of neutrophils during infection critically depend on microbicidal and proteolytic proteins stored in primary, secondary and tertiary granules that are released into the phagosome or into the extracellular space upon degranulation. Granules are generated during granulopoiesis and impaired granule production or granule protein sorting has been linked to inefficient pathogen clearance resulting in recurrent bacterial and fungal infections. Here, we studied the role of the membrane protein secretory carrier associated membrane protein 3 (SCAMP3) for neutrophil defense functions. We generated Scamp3 knockout (KO) Hoxb8 cells and found that killing of Escherichia coli by Scamp3 KO Hoxb8 cell-derived neutrophils (dHoxb8 cells) was compromised as compared to control dHoxb8 cells in vitro. Mass spectrometric and Western blot analyses revealed a significant reduction of primary, secondary, and tertiary granule proteins in the genetic absence of Scamp3, resulting in a reduced overall granularity of these cells. Accordingly, degranulation was reduced in Scamp3 KO dHoxb8 cells compared to control dHoxb8 cells. Similarly, SCAMP3 deficiency in zebrafish resulted in reduced neutrophil granularity in comparison to wild-type animals. However, neutrophil migration towards sites of E. coli infection was unaffected in scamp3 KO zebrafish larvae. In summary, SCAMP3 represents an important novel player in granule equipment and degranulation, with key functions in neutrophil defense mechanisms during host-pathogen interactions in vitro. Brief summary sentence: The membrane protein secretory carrier associated membrane protein 3 (SCAMP3) is essential for proper protein equipment of neutrophil granules and Scamp3-deficient neutrophils have an impaired bacterial killing capacity in vitro.

physiology↗