Publications by authors named "Joshua Linnert"

Article Synopsis
  • Usher syndrome (USH) is a common hereditary sensory disorder that leads to progressive vision and hearing loss, linked to mutations in the ADGRV1 and CIB2 genes, associated with subtypes USH2C and USH1J.
  • The study identified proteins interacting with CIB2 and compared them with those of ADGRV1, revealing significant overlap in their networks, indicating shared cellular pathways.
  • Validation of these protein interactions showed mutual interaction between ADGRV1 and CIB2 and their role in primary cilia function, suggesting common molecular mechanisms in the pathogenesis of both Usher syndrome and Bardet-Biedl syndrome (BBS).
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VLGR1/ADGRV1 (very large G protein-coupled receptor-1) is the largest known adhesion G protein-coupled receptor. Mutations in VLGR1/ADGRV1 cause Usher syndrome (USH), the most common form of hereditary deaf-blindness, and have been additionally linked to epilepsy. Although VLGR1/ADGRV1 is almost ubiquitously expressed, little is known about the subcellular function and signalling of the VLGR1 protein and thus about mechanisms underlying the development of diseases.

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VLGR1/ADGRV1 (very large G protein-coupled receptor-1) is the largest adhesion G protein-coupled receptor (aGPCR). Mutations in VLGR1/ADGRV1 are associated with human Usher syndrome, the most common form of deaf-blindness, and also with epilepsy in humans and mice. VLGR1 is expressed almost ubiquitously but is mainly found in the CNS and in the sensory cells of the eye and inner ear.

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Human Usher syndrome (USH) is the most common form of hereditary combined deaf-blindness. USH is a complex genetic disorder, and the pathomechanisms underlying the disease are far from being understood, especially in the eye and retina. The gene encodes the scaffold protein harmonin which organizes protein networks due to binary interactions with other proteins, such as all USH proteins.

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Article Synopsis
  • VLGR1 (ADGRV1) is the largest member of the adhesion GPCR family, with mutations linked to Usher syndrome and childhood absence epilepsy.
  • Research shows VLGR1 interacts with proteins associated with the endoplasmic reticulum (ER) and mitochondria, particularly at mitochondria-associated ER membranes (MAMs).
  • Studies using various assays confirmed that VLGR1 is crucial for maintaining MAM structure and regulating calcium (Ca) homeostasis between the ER and mitochondria.
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Usher syndrome (USH) is the most common form of monogenic deaf-blindness. Loss of vision is untreatable and there are no suitable animal models for testing therapeutic strategies of the ocular constituent of USH, so far. By introducing a human mutation into the harmonin-encoding USH1C gene in pigs, we generated the first translational animal model for USH type 1 with characteristic hearing defect, vestibular dysfunction, and visual impairment.

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The ARF family of regulatory GTPases is ancient, with 16 members predicted to have been present in the last eukaryotic common ancestor. Our phylogenetic profiling of paralogues in diverse species identified four family members whose presence correlates with that of a cilium/flagellum: ARL3, ARL6, ARL13, and ARL16. No prior evidence links ARL16 to cilia or other cell functions, despite its presence throughout eukaryotes.

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ELMODs are a family of three mammalian paralogues that display GTPase-activating protein (GAP) activity toward a uniquely broad array of ADP-ribosylation factor (ARF) family GTPases that includes ARF-like (ARL) proteins. ELMODs are ubiquitously expressed in mammalian tissues, highly conserved across eukaryotes, and ancient in origin, being present in the last eukaryotic common ancestor. We described functions of ELMOD2 in immortalized mouse embryonic fibroblasts (MEFs) in the regulation of cell division, microtubules, ciliogenesis, and mitochondrial fusion.

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Article Synopsis
  • ELMOD2 is a GTPase-activating protein that influences mitochondrial fusion, microtubule stability, and cytokinesis by working with ARL2 and ARF6.
  • Mouse cells lacking ELMOD2 showed issues with cilia formation, including increased ciliation and abnormal morphology, suggesting a disruption in normal cilia-related processes.
  • The involvement of ELMOD2, ARL2, and Rootletin in a common pathway was suggested, important for controlling ciliary development and maintaining centrosome cohesion, with potential regulation occurring upstream of CP110 in the ciliation pathway.
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The identification of genetic defects that underlie inherited retinal diseases (IRDs) paves the way for the development of therapeutic strategies. Nonsense mutations caused approximately 12% of all IRD cases, resulting in a premature termination codon (PTC). Therefore, an approach that targets nonsense mutations could be a promising pharmacogenetic strategy for the treatment of IRDs.

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