Case-inspired exploration of renin mutations in autosomal dominant tubulointerstitial kidney disease: not all paths lead to the endoplasmic reticulum.

BACKGROUND: Autosomal dominant tubulointerstitial kidney disease (ADTKD) results from mutations in various genes, including REN, UMOD, MUC1, and HNF1B. ADTKD due to REN mutations (ADTKD-REN) is often characterized as a proteinopathy that triggers the endoplasmic reticulum stress (ERS) cascade, potentially sharing similarities with ADTKD-UMOD and ADTKD-MUC1 at the cellular level. This study, inspired by a patient harboring a W17R mutation, investigates ERS activation by this mutation alongside two other renin variants, W10R and L381P. METHODS: We established stable cell lines expressing both wild-type and mutated renin forms (W17R, W10R, and L381P). Using luciferase reporter assays, RT-qPCR, and confocal microscopy, we evaluated ERS activation, determined the cellular localization of the renin variants, and characterized the mitochondrial network in the W17R line. RESULTS: The L381P line exhibited ERS activation, including transcriptional upregulation of MANF and CRELD2. No ERS activation was observed in the W17R line, while the W10R line exhibited intermediate characteristics. Notably, the W17R variant was misrouted to the mitochondria resulting in changes of the mitochondrial network organisation. CONCLUSIONS: ERS activation is not a universal response to different renin mutations in ADTKD-REN. The pathogenesis of the W17R mutation may involve mitochondrial dysfunction rather than the ER pathway, albeit further research is needed to substantiate this hypothesis fully. Testing CRELD2 and MANF as targeted therapy markers for a specific subgroup of ADTKD-REN patients is recommended. Additionally, fludrocortisone treatment has shown efficacy in stabilizing the renal function of our patient over a four-year period without significant side effects.

Everybody wants to move-Evolutionary implications of trunk muscle differentiation in vertebrate species.

In our review we have completed current knowledge on myotomal myogenesis in model and non-model vertebrate species (fishes, amphibians, reptiles, birds and mammals) at morphological and molecular levels. Data obtained from these studies reveal distinct similarities and differences between amniote and anamniote species. Based on the available data, we decided to present evolutionary implications in vertebrate trunk muscle development. Despite the fact that in all vertebrates muscle fibres are multinucleated, the pathways leading to them vary between vertebrate taxa. In fishes during early myogenesis myoblasts differentiate into multinucleated lamellae or multinucleate myotubes. In amphibians, myoblasts fuse to form multinucleated myotubes or, bypassing fusion, directly differentiate into mononucleated myotubes. Furthermore, mononucleated myotubes were also observed during primary myogenesis in amniotes. The mononucleated state of myogenic cells could be considered as an old phylogenetic, plesiomorphic feature, whereas direct multinuclearity of myotubes has a synapomorphic character. On the other hand, the explanation of this phenomenon could also be linked to the environmental conditions in which animals develop. The similarities observed in vertebrate myogenesis might result from a conservative myogenic programme governed by the Pax3/Pax7 and myogenic regulatory factor (MRF) network, whereas differences in anamniotes and amniotes are established by spatiotemporal pattern expression of MRFs during muscle differentiation and/or environmental conditions.

Zebrafish: A Model for the Study of Toxicants Affecting Muscle Development and Function.

The rapid progress in medicine, agriculture, and allied sciences has enabled the development of a large amount of potentially useful bioactive compounds, such as drugs and pesticides. However, there is another side of this phenomenon, which includes side effects and environmental pollution. To avoid or minimize the uncontrollable consequences of using the newly developed compounds, researchers seek a quick and effective means of their evaluation. In achieving this goal, the zebrafish (Danio rerio) has proven to be a highly useful tool, mostly because of its fast growth and development, as well as the ability to absorb the molecules diluted in water through its skin and gills. In this review, we focus on the reports concerning the application of zebrafish as a model for assessing the impact of toxicants on skeletal muscles, which share many structural and functional similarities among vertebrates, including zebrafish and humans.

Assessment of the Preventive Effect of L-carnitine on Post-statin Muscle Damage in a Zebrafish Model.

Statins, such as lovastatin, are lipid-lowering drugs (LLDs) that have been used to treat hypercholesterolaemia, defined as abnormally elevated cholesterol levels in the patient's blood. Although statins are considered relatively safe and well tolerated, recipients may suffer from adverse effects, including post-statin myopathies. Many studies have shown that supplementation with various compounds may be beneficial for the prevention or treatment of side effects in patients undergoing statin therapy. In our study, we investigated whether L-carnitine administered to zebrafish larvae treated with lovastatin alleviates post-statin muscle damage. We found that exposure of zebrafish larvae to lovastatin caused skeletal muscle disruption observed as a reduction of birefringence, changes in muscle ultrastructure, and an increase in atrogin-1. Lovastatin also affected heart performance and swimming behaviour of larvae. Our data indicated that the muscle-protective effect of L-carnitine is partial. Some observed myotoxic effects, such as disruption of skeletal muscle and increase in atrogin-1 expression, heart contraction could be rescued by the addition of L-carnitine. Others, such as slowed heart rate and reduced locomotion, could not be mitigated by L-carnitine supplementation.

New insights into the criteria of functional heterozygosity of the Apis mellifera complementary sex determining gene-Discovery of a functional allele pair differing by a single amino acid.

The complementary sex determiner (csd) gene is responsible for controlling the sex-determination molecular switch in western honey bees (Apis mellifera): bees that are heterozygous for csd develop into females, whereas bees that are hemizygous or homozygous develop into males. The homozygous diploid males are destroyed at an early stage of their development. It has been proposed that the minimal number of amino acid differences between two csd alleles needed to fully determine femaleness is five and it has also been shown that smaller differences may result in forming an evolutionary intermediate that is not fully capable of female determination, but has increased fitness compared to the homozygous genotype. In this study, we have implemented a terminal restriction length polymorphism-based method of identifying and distinguishing paternal alleles in a given bee colony and assigning them to a particular maternal allele in order to gather information on large number of functional csd pairs and also to identify, to some extent, genotypes that are underrepresented or absent in bee colonies. The main finding of this study is the identification of a fully functional genotype consisting of csd alleles that differed from each other by a one amino acid position. The individuals carrying this genotype expressed only female-specific transcripts of feminizer and double-sex genes. By comparing the sequences differences between the csd pair identified in our study with those described earlier, we conclude that functional heterozygosity of the csd gene is dependent not only on the number of the amino acid differences but also on the sequence context and position of the change. The discovery of a functional allele pair differing by a single amino acid also implies that the generation of a new csd specificity may also occur during a single mutation step with no need for evolutionary intermediates accumulating further mutations.

Characterization of Hspb8 in Zebrafish.

Hspb8 is a member of the small heat shock protein (sHSP) family. Its expression is known to be upregulated under heat shock. This protein interacts with different partners and can, therefore, be involved in various processes relevant to tissue integrity and functioning. In humans, mutations in the gene encoding Hspb8 can lead to the development of various diseases such as myopathies and neuropathies. In our study, we aimed to perform an in-depth characterization of zebrafish Hspb8 during zebrafish development. We applied techniques such as RT-qPCR, Western blot, immunofluorescence, co-immunoprecipitation, LC-MS, and morpholino-mediated knockdown. We broadened the knowledge regarding zebrafish hspb8 expression during development under normal and heat shock conditions as well as its tissue- and subcellular-specific localization. A co-IP analysis allowed us to conclude that zebrafish Hspb8 can interact with proteins such as Bag3 and Hsc70, which are crucial for formation of an autophagy-inducing complex. We also demonstrated that hspb8 morpholino-mediated knockdown has an impact on zebrafish embryos' morphology, muscle ultrastructure, and motility behavior. Our research provides a valuable resource for the potential use of the zebrafish as a model for studying pathological conditions associated with hspb8 disorders.