Bardet-Biedl syndrome (BBS) is a pleiotropic ciliopathy caused by dysfunction of the BBSome, a cargo adaptor essential for export of transmembrane receptors from cilia. Although actin-dependent ectocytosis has been proposed to compensate defective cargo retrieval, its molecular basis remains unclear, especially in relation to BBS pathology. In this study, we investigated how actin polymerization and ectocytosis are regulated within the cilium. Our findings reveal that ciliary CDC42, a RHO-family GTPase triggers in situ actin polymerization, ciliary ectocytosis, and cilia shortening in BBSome-deficient cells. Activation of the Sonic Hedgehog pathway further enhances CDC42 activity specifically in BBSome-deficient cilia. Inhibition of CDC42 in BBSome-deficient cells decreases the frequency and duration of ciliary actin polymerization events, causing buildup of G protein coupled receptor 161 (GPR161) in bulges along the axoneme during Sonic Hedgehog signaling. Overall, our study identifies CDC42 as a key trigger of ciliary ectocytosis. Hyperactive ciliary CDC42 and ectocytosis and the resulting loss of ciliary material might contribute to BBS disease severity.

• Klíčová slova
• Actin, Bardet-Biedl Syndrome, CDC42, Cilium, Ectocytosis,
• MeSH
• aktiny * metabolismus   MeSH
• Bardetův-Biedlův syndrom * metabolismus   genetika   patologie   MeSH
• cdc42 protein vázající GTP * metabolismus   genetika   MeSH
• cilie * metabolismus   MeSH
• lidé MeSH
• myši MeSH
• proteiny hedgehog metabolismus   MeSH
• receptory spřažené s G-proteiny metabolismus   genetika   MeSH
• signální transdukce MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• aktiny * MeSH
• cdc42 protein vázající GTP * MeSH
• proteiny hedgehog MeSH
• receptory spřažené s G-proteiny MeSH

Bardet-Biedl syndrome (BBS) is an archetypal ciliopathy caused by dysfunction of primary cilia. BBS affects multiple tissues, including the kidney, eye and hypothalamic satiety response. Understanding pan-tissue mechanisms of pathogenesis versus those which are tissue-specific, as well as gauging their associated inter-individual variation owing to genetic background and stochastic processes, is of paramount importance in syndromology. The BBSome is a membrane-trafficking and intraflagellar transport (IFT) adaptor protein complex formed by eight BBS proteins, including BBS1, which is the most commonly mutated gene in BBS. To investigate disease pathogenesis, we generated a series of clonal renal collecting duct IMCD3 cell lines carrying defined biallelic nonsense or frameshift mutations in Bbs1, as well as a panel of matching wild-type CRISPR control clones. Using a phenotypic screen and an unbiased multi-omics approach, we note significant clonal variability for all assays, emphasising the importance of analysing panels of genetically defined clones. Our results suggest that BBS1 is required for the suppression of mesenchymal cell identities as the IMCD3 cell passage number increases. This was associated with a failure to express epithelial cell markers and tight junction formation, which was variable amongst clones. Transcriptomic analysis of hypothalamic preparations from BBS mutant mice, as well as BBS patient fibroblasts, suggested that dysregulation of epithelial-to-mesenchymal transition (EMT) genes is a general predisposing feature of BBS across tissues. Collectively, this work suggests that the dynamic stability of the BBSome is essential for the suppression of mesenchymal cell identities as epithelial cells differentiate.

• Klíčová slova
• Bardet–Biedl syndrome, Wnt signalling, collecting duct cells, epithelial-to-mesenchymal transition, fibrosis, kidney, primary cilia,
• MeSH
• Bardetův-Biedlův syndrom * genetika   metabolismus   patologie   MeSH
• cilie metabolismus   MeSH
• lidé MeSH
• myši knockoutované MeSH
• myši MeSH
• proteiny asociované s mikrotubuly metabolismus   MeSH
• proteiny metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• Bbs1 protein, human MeSH Prohlížeč
• Bbs1 protein, mouse MeSH Prohlížeč
• proteiny asociované s mikrotubuly MeSH
• proteiny MeSH

Components of the intraflagellar transport (IFT) system that regulates the assembly of the primary cilium are co-opted by the non-ciliated T cell to orchestrate polarized endosome recycling and to sustain signaling during immune synapse formation. Here, we investigated the potential role of Bardet-Biedl syndrome 1 protein (BBS1), an essential core component of the BBS complex that cooperates with the IFT system in ciliary protein trafficking, in the assembly of the T cell synapse. We demonstrated that BBS1 allows for centrosome polarization towards the immune synapse. This function is achieved through the clearance of centrosomal F-actin and its positive regulator WASH1 (also known as WASHC1), a process that we demonstrated to be dependent on the proteasome. We show that BBS1 regulates this process by coupling the 19S proteasome regulatory subunit to the microtubule motor dynein for its transport to the centrosome. Our data identify the ciliopathy-related protein BBS1 as a new player in T cell synapse assembly that functions upstream of the IFT system to set the stage for polarized vesicular trafficking and sustained signaling. This article has an associated First Person interview with the first author of the paper.

• Klíčová slova
• Bardet–Biedl syndrome, Centrosome, Dynein, Immune synapse, Primary cilium, Proteasome,
• MeSH
• Bardetův-Biedlův syndrom * genetika   MeSH
• cilie * MeSH
• endozomy MeSH
• lidé MeSH
• polarita buněk MeSH
• proteiny asociované s mikrotubuly genetika   MeSH
• synapse MeSH
• T-lymfocyty MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• Bbs1 protein, human MeSH Prohlížeč
• proteiny asociované s mikrotubuly MeSH

Bardet-Biedl Syndrome (BBS) is a pleiotropic genetic disease caused by the dysfunction of primary cilia. The immune system of patients with ciliopathies has not been investigated. However, there are multiple indications that the impairment of the processes typically associated with cilia may have influence on the hematopoietic compartment and immunity. In this study, we analyze clinical data of BBS patients and corresponding mouse models carrying mutations in Bbs4 or Bbs18. We find that BBS patients have a higher prevalence of certain autoimmune diseases. Both BBS patients and animal models have altered red blood cell and platelet compartments, as well as elevated white blood cell levels. Some of the hematopoietic system alterations are associated with BBS-induced obesity. Moreover, we observe that the development and homeostasis of B cells in mice is regulated by the transport complex BBSome, whose dysfunction is a common cause of BBS. The BBSome limits canonical WNT signaling and increases CXCL12 levels in bone marrow stromal cells. Taken together, our study reveals a connection between a ciliopathy and dysregulated immune and hematopoietic systems.

• Klíčová slova
• Bardet-Biedl Syndrome, CXCL12, ciliopathy, immunity, obesity,
• MeSH
• autoimunitní nemoci * MeSH
• Bardetův-Biedlův syndrom * komplikace   genetika   MeSH
• cilie MeSH
• hematopoéza * genetika   MeSH
• lidé MeSH
• modely nemocí na zvířatech MeSH
• mutace MeSH
• myši MeSH
• proteiny asociované s mikrotubuly genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• BBS4 protein, mouse MeSH Prohlížeč
• proteiny asociované s mikrotubuly MeSH

Bardet-Biedl syndrome (BBS) is a pleiotropic ciliopathy caused by dysfunction of primary cilia. More than half of BBS patients carry mutations in one of eight genes encoding for subunits of a protein complex, the BBSome, which mediates trafficking of ciliary cargoes. In this study, we elucidated the mechanisms of the BBSome assembly in living cells and how this process is spatially regulated. We generated a large library of human cell lines deficient in a particular BBSome subunit and expressing another subunit tagged with a fluorescent protein. We analyzed these cell lines utilizing biochemical assays, conventional and expansion microscopy, and quantitative fluorescence microscopy techniques: fluorescence recovery after photobleaching and fluorescence correlation spectroscopy. Our data revealed that the BBSome formation is a sequential process. We show that the pre-BBSome is nucleated by BBS4 and assembled at pericentriolar satellites, followed by the translocation of the BBSome into the ciliary base mediated by BBS1. Our results provide a framework for elucidating how BBS-causative mutations interfere with the biogenesis of the BBSome.

• Klíčová slova
• BBSome, Bardet-Biedl Syndrome, Bardet-Biedl syndrome, assembly, ciliopathy, cilium, genetic disease, microscopic imaging, primary cilium, protein assembly, protein sorting,
• MeSH
• Bardetův-Biedlův syndrom genetika   metabolismus   patologie   MeSH
• buněčné linie MeSH
• cilie metabolismus   MeSH
• CRISPR-Cas systémy genetika   MeSH
• cytoplazma metabolismus   MeSH
• editace genu MeSH
• fluorescenční mikroskopie MeSH
• FRAP MeSH
• lidé MeSH
• mutace MeSH
• podjednotky proteinů genetika   metabolismus   MeSH
• proteiny asociované s mikrotubuly nedostatek   genetika   metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• Bbs1 protein, human MeSH Prohlížeč
• BBS4 protein, human MeSH Prohlížeč
• podjednotky proteinů MeSH
• proteiny asociované s mikrotubuly MeSH

Bardet-Biedl syndrome (BBS) is a recessive genetic disease causing multiple organ anomalies. Most patients carry mutations in genes encoding for the subunits of the BBSome, an octameric ciliary transport complex, or accessory proteins involved in the BBSome assembly or function. BBS proteins have been extensively studied using in vitro, cellular, and animal models. However, the molecular functions of particular BBS proteins and the etiology of the BBS symptoms are still largely elusive. In this study, we applied a meta-analysis approach to study the genotype-phenotype association in humans using our database of all reported BBS patients. The analysis revealed that the identity of the causative gene and the character of the mutation partially predict the clinical outcome of the disease. Besides their potential use for clinical prognosis, our analysis revealed functional differences of particular BBS genes in humans. Core BBSome subunits BBS2, BBS7, and BBS9 manifest as more critical for the function and development of kidneys than peripheral subunits BBS1, BBS4, and BBS8/TTC8, suggesting that incomplete BBSome retains residual function at least in the kidney.

• Klíčová slova
• BBS, BBSome, Bardet-Biedl syndrome, ciliopathy, genotype-phenotype, kidney disease, meta-analysis, rare disease,
• MeSH
• ADP-ribosylační faktory genetika   MeSH
• Bardetův-Biedlův syndrom diagnóza   genetika   MeSH
• fenotyp * MeSH
• genetická predispozice k nemoci * MeSH
• genetické asociační studie * metody   MeSH
• genotyp * MeSH
• kognitivní dysfunkce genetika   MeSH
• ledviny abnormality   MeSH
• lidé MeSH
• mutace MeSH
• nemoci ledvin vrozené   genetika   MeSH
• penetrance MeSH
• proteiny genetika   MeSH
• vrozené vady genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• metaanalýza MeSH
• práce podpořená grantem MeSH
• Názvy látek
• ADP-ribosylační faktory MeSH
• ARL6 protein, human MeSH Prohlížeč
• Bbs2 protein, human MeSH Prohlížeč
• proteiny MeSH

The transition zone (TZ) of eukaryotic cilia and flagella is a structural intermediate between the basal body and the axoneme that regulates ciliary traffic. Mutations in genes encoding TZ proteins (TZPs) cause human inherited diseases (ciliopathies). Here, we use the trypanosome to identify TZ components and localize them to TZ subdomains, showing that the Bardet-Biedl syndrome complex (BBSome) is more distal in the TZ than the Meckel syndrome (MKS) complex. Several of the TZPs identified here have human orthologs. Functional analysis shows essential roles for TZPs in motility, in building the axoneme central pair apparatus and in flagellum biogenesis. Analysis using RNAi and HaloTag fusion protein approaches reveals that most TZPs (including the MKS ciliopathy complex) show long-term stable association with the TZ, whereas the BBSome is dynamic. We propose that some Bardet-Biedl syndrome and MKS pleiotropy may be caused by mutations that impact TZP complex dynamics.

• Klíčová slova
• BBSome, MKS/B9 complex, cilium/flagellum, transition zone, trypanosome,
• MeSH
• Bardetův-Biedlův syndrom genetika   metabolismus   MeSH
• bazální tělíska metabolismus   ultrastruktura   MeSH
• cilie genetika   metabolismus   MeSH
• ciliopatie genetika   metabolismus   MeSH
• cytoskelet metabolismus   ultrastruktura   MeSH
• encefalokéla genetika   metabolismus   MeSH
• flagella genetika   metabolismus   ultrastruktura   MeSH
• fluorescenční mikroskopie MeSH
• kompartmentace buňky MeSH
• lidé MeSH
• mutace MeSH
• polycystická choroba ledvin genetika   metabolismus   MeSH
• poruchy ciliární motility genetika   metabolismus   MeSH
• proteom genetika   metabolismus   MeSH
• protozoální proteiny genetika   metabolismus   MeSH
• retinopathia pigmentosa MeSH
• RNA interference MeSH
• transmisní elektronová mikroskopie MeSH
• Trypanosoma genetika   metabolismus   ultrastruktura   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• proteom MeSH
• protozoální proteiny MeSH

Animal models and family studies led to the identification ofcases of rare monogenic forms of human obesity. Rare Mendelian syndromes as Prader-Willi syndrome and Bardet-Biedl syndrome represent cases of genetically determined obesity. Genome wide linkage and classical candidate gene studies were in general unsuccessful concerning the identification of genes of common obesity. On the other hand, genome-wide association studies (GWAS) were found to be effective, as also variants with only a minor effect have been detected. Seventeen polygenic variants influencing body weight regulation were clearly confirmed. It is assumed that more of these variants exist and therefore they might be identified in near future by GWAS. It is possible that the size effect of some variants can be within few grams of body weight. In order to detect variants with small effect there is a need of meta-analyses based on hundreds of thousands of individuals. Newly identified variants result in an increase of 0.06-0.33 kg/m2 of BMI per allele. In an adult of an average height of 170cm, it corresponds to 173-954 g per risk allele. It was estimated that subjects carrying 13 or more risk alleles were on average 1.46 body mass index units heavier (representing 3.7-4.7 kg) than carriers of less than three risk alleles. Further research should be focused on a gene-gene interaction. An interaction ofgene and environment should be statistically analyzed in adequate proband cohorts. If we are able to identify a large number of risk variants, the predisposition to a certain disease could be predicted. Currently a detailed family history has more predictive power.

• MeSH
• Alströmův syndrom genetika   MeSH
• Bardetův-Biedlův syndrom genetika   MeSH
• celogenomová asociační studie MeSH
• epigeneze genetická MeSH
• genetická predispozice k nemoci MeSH
• lidé MeSH
• obezita epidemiologie   genetika   MeSH
• Praderův-Williho syndrom genetika   MeSH
• tělesná hmotnost genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• anglický abstrakt MeSH
• časopisecké články MeSH
• přehledy MeSH

• Klíčová slova
• EYE MANIFESTATIONS *, LAURENCE-MOON-BIEDL SYNDROME *, PIGMENTATION DISORDERS *, RETINAL PIGMENTS *,
• MeSH
• Bardetův-Biedlův syndrom * MeSH
• Laurenceův-Moonův syndrom * MeSH
• lidé MeSH
• oční symptomy * MeSH
• poruchy pigmentace * MeSH
• retinální pigmenty * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• retinální pigmenty * MeSH

• Klíčová slova
• LAURENCE-MOON-BIEDL SYNDROME *, MENTAL DEFICIENCY *,
• MeSH
• Bardetův-Biedlův syndrom * MeSH
• Laurenceův-Moonův syndrom * MeSH
• lidé MeSH
• mentální retardace * MeSH
• Měsíc * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH