Biology subjects

Ciura, S.

Publications and source records attributed to Ciura, S..

3 recordsLinked to original sources

bioRxiv2024

Functional assessment of a kcnb1 knock-out zebrafish to model KCNB1-related neurodevelopmental and epileptic disorders

KEY POINTSO_LIkcnb1 is expressed in distinct cell subtypes and various regions of the central nervous system in zebrafish C_LIO_LIBrain anatomy and neuronal circuits are not disrupted in the kcnb1 loss-of-function zebrafish model C_LIO_LILoss of kcnb1 leads to altered behavior phenotype, light and sound-induced locomotor impairments C_LIO_LIkcnb1 knock-out zebrafish exhibit increased locomotor sensitivity to PTZ and elevated expression of epileptogenesis-related genes C_LIO_LIkcnb1-/- larvae show spontaneous and provoked epileptiform-like electrographic activity associated with disrupted GABA regulation C_LI ObjectiveKCNB1 encodes an -subunit of the delayed-rectifier voltage-dependent potassium channel Kv2.1. De novo pathogenic variants of KCNB1 have been linked to developmental and epileptic encephalopathies (DEE), diagnosed in early childhood and sharing limited treatment options. Loss-of-function (LOF) of KCNB1 with dominant negative effects has been proposed as the pathogenic mechanism in these disorders. Here, we aim to characterize a knock-out (KO) zebrafish line targeting kcnb1 (kcnb1+/- and kcnb1-/-) for investigating DEEs. MethodsThis study presents the phenotypic analysis of a kcnb1 knock-out zebrafish model, obtained by CRISPR/Cas9 mutagenesis. Through a combination of immunohistochemistry, behavioral assays, electrophysiological recordings, and neurotransmitter quantifications, we have characterized the expression, function, and impact of this kcnb1 LOF model at early stages of development. ResultsIn wild-type larval zebrafish, kcnb1 was found in various regions of the central nervous system and in diverse cell subtypes including neurons, oligodendrocytes and microglial cells. Both kcnb1+/- and kcnb1-/- zebrafish displayed impaired swimming behavior and "epilepsy-like" features that persisted through embryonic and larval development, with variable severity. When exposed to the chemoconvulsant pentylenetetrazol (PTZ), both mutant models showed elevated locomotor activity. In addition, PTZ-exposed kcnb1-/- larvae exhibited higher bdnf mRNA expression and activated c-Fos positive neurons in the telencephalon. This same model presents spontaneous and provoked epileptiform-like electrographic activity associated with disrupted GABA regulation. In this KO model, neuronal circuit organization remained unaffected. SignificanceWe conclude that kcnb1 knock-out in zebrafish leads to early-onset phenotypic features reminiscent of DEEs, affecting neuronal functions and primarily inhibitory pathways in developing embryonic and larval brains. This study highlights the relevance of this model for investigating developmental neuronal signaling pathways in KCNB1-related DEEs.

neuroscience↗

bioRxiv2024

Spatial dynamics of peripheral and central nervous system infection by an interferon-inducing neuroinvasive virus

Organ-to-organ dissemination of viruses is a critical feature of host-virus interactions. In particular, neuroinvasive viruses are able to enter the central nervous systems (CNS), which may result in death or permanent neurological impairment. The complex mechanisms underpinning this spread are poorly understood, as they depend on a variety of parameters, including initial site of entry, route of access to the CNS, and immune responses. To better understand these phenomena, we analyzed the spatial dynamics of Sindbis virus (SINV) dissemination in transparent zebrafish larvae. Using fluorescent reporter viruses, we observed that SINV readily invaded the CNS after inoculation at various peripheral sites. From tail muscle, the virus used dorsal root ganglia (DRG) sensory neurons as a gateway to the spinal cord and further propagation to the brain. While peripheral infection was systematically transient, due to the key protective role of the strong and rapid type I interferon (IFN) response, CNS infection was persistent and more variable. Within the CNS, viral dissemination resulted both from long-distance axonal transport and short distance shedding, and IFN response was local, while it was systemic in the periphery. A mathematical model was built on this quantitative imaging foundation, that provided additional insight on the parameters of this infection, such as the rate of new virion production, estimated around 1 to 2 infective virions per productively infected cell per hour; the occurrences of CNS entry events, which was 2 to 3 per larva; or the impact of the IFN response, which did not only prevent new infections but accelerated the death of infected cells.

microbiology↗

bioRxiv2023

Abnormal autophagy is a critical mechanism in TANGO2-related rhabdomyolysis

Patients with pathogenic variants in the TANGO2 gene suffer from severe and recurrent rhabdomyolysis (RM) episodes precipitated by fasting. Since starvation promotes autophagy induction, we wondered whether TANGO2-related muscle symptoms result from autophagy insufficiency to meet cellular demands in stress conditions. Autophagy functioning was analyzed in vitro, in primary skeletal muscle cells from TANGO2 patients in basal and fasting conditions. In addition, we developed a tango2 morphant zebrafish model to assess the effect of tango2 knockdown (KD) on locomotor function and autophagy efficiency in vivo. We report that TANGO2 mutations are associated with decreased LC3-II levels upon starvation in primary muscle cells, but not in fibroblasts. In zebrafish larvae, tango2 knockdown induces locomotor defects characterized by reduced evoked movements which are exacerbated by exposure to atorvastatin, a compound known to cause RM. Importantly, RM features of tango2 KD are also associated with autophagy and mitophagy defects in zebrafish. Calpeptin treatment, a known activator of autophagy, is sufficient to rescue the locomotor properties, thanks to its beneficial effect on autophagy functioning in zebrafish and independently to its effect on calpain activity. LC3-II levels of primary muscle cells of TANGO2 patients are also improved by calpeptin treatment. Overall, we demonstrate that TANGO2 plays an important role in autophagy, and that autophagy efficiency is critical to prevent RM, thus giving rise to new therapeutic perspectives in the prevention of these life-threatening episodes in TANGO2 pathology.

cell biology↗