Biology subjects

Hoogewijs, D.

Publications and source records attributed to Hoogewijs, D..

3 recordsLinked to original sources

bioRxiv2026

Calcium-dependent proteolysis of the chimeric androglobin reveals altered localization of its isolated globin domain

Androglobin (ADGB), a protein essential for spermatogenesis, is the most structurally unusual member of the vertebrate globin superfamily. It combines a calpain-like domain with a circularly permuted globin domain containing an embedded calmodulin-binding IQ motif, an architecture suggesting complex regulatory functions that remain poorly understood. Here, we investigated whether ADGB undergoes calcium-dependent post-translational processing, like it has been described for other calpains. ADGB underwent robust proteolytic processing upon calcium stimulation, generating several stable cleavage products following ectopic expression in mammalian cells. In vitro proteolysis assays demonstrated that ADGB cleavage requires cytoplasmic factor(s) and is strongly enhanced by Ca2+. While this process is sensitive to pan-calpain inhibition, siRNA-mediated knockdown excluded calpain 1 (CAPN1) and calpain 2 (CAPN2) as primary mediators of ADGB cleavage. In contrast, depletion of the calpain small regulatory subunit CAPNS1 markedly reduced calcium-dependent ADGB proteolysis, implicating a CAPNS1-associated calcium-responsive proteolytic pathway. Domain-mapping analyses localized the major cleavage hotspot between the N-terminal calpain-like domain and the globin-containing C-terminal region, indicating that proteolysis separates the protease-like and globin modules of the ADGB chimera. The isolated globin domain displayed enhanced interaction with calmodulin compared with full-length ADGB, whereas the extended C-terminal region impeded this interaction. Furthermore, unlike full-length ADGB, the isolated globin domain exhibited preferential localization to centrosomal structures. Collectively, these findings identify calcium-dependent proteolysis and altered subcellular localization of the isolated globin domain as previously unrecognized properties of ADGB that may be relevant to its role in ciliary biology.

Cell Biology↗

bioRxiv2024

Endogenously produced hydrogen cyanide serves as a novel mammalian gasotransmitter

Small, gaseous molecules, known as gasotransmitters (NO, CO, H2S), are produced endogenously in mammalian cells and serve important biological roles. Hydrogen cyanide, traditionally considered a cytotoxic molecule in mammals, serves as an endogenous mediator in several plants and bacterial species. Here we show that low concentrations of cyanide are generated endogenously in mouse liver and human hepatocytes. Cyanide production is stimulated by glycine, occurs at the low pH of lysosomes and requires peroxidase activity. Cyanide, in turn, is detectable in several cellular compartments. Cyanide is also detectable basally in the blood of mice; its levels increase after treatment of the animals with glycine. Rhodanese activity regulates endogenous cyanide levels. Cyanide, when generated endogenously at an optimal level, exerts stimulatory effects on mitochondrial bioenergetics, cell metabolism and cell proliferation. Dysregulation of endogenous cyanide, either below or above optimal levels, impairs cellular bioenergetics. The regulatory effects of cyanide are in part mediated by posttranslational modification of cysteine residues via protein cyanylation; cyanylated protein residues can be detected basally, and increase after treatment with glycine. Controlled low-dose cyanide supplementation exhibits cytoprotective effects, as demonstrated in hypoxia and reoxygenation models in vitro and in vivo. However, pathologically elevated cyanide production, as demonstrated in nonketotic hyperglycinemia - an autosomal recessive disease of glycine metabolism - is deleterious to the cells.

biochemistry↗

bioRxiv2021

Androglobin, a chimeric mammalian globin, is required for male fertility

Spermatogenesis is a highly specialised process, involving multiple dedicated pathways and regulatory check-points. Defects ultimately lead to male sub-fertility or sterility, and numerous aspects of mammalian sperm formation remain unknown. The predominant expression of the latest globin family member, androglobin (Adgb) in mammalian testis tissue prompted us to assess its physiological function in spermatogenesis. Adgb knockout mice display male infertility, reduced testis weight, impaired maturation of elongating spermatids, abnormal sperm shape and ultrastructural defects in microtubule and mitochondrial organisation. Epididymal sperm from Adgb knockout animals display multiple flagellar malformations including coiled, bifide or shortened flagella, and erratic acrosomal development. Following immunoprecipitation and mass spectrometry, we could identify septin 10 (Sept10) as interactor of Adgb. The Sept10-Adgb interaction was confirmed both in vivo using testis lysates, and in vitro by reciprocal co-immunoprecipitation experiments. Furthermore, absence of Adgb leads to mislocalisation of Sept10 in sperm, indicating defective manchette and sperm annulus formation. Finally, in vitro data suggest that Adgb contributes to Sept10 proteolysis in a calmodulin (CaM)-dependent manner. Collectively, our results provide evidence that Adgb is essential for murine spermatogenesis and further suggest that interdependence between Adgb and Sept10 is required for sperm head shaping via the manchette and proper flagellum formation.

developmental biology↗