Browsing by Author "Kaplan, Oktay I."

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ARL13B regulates juxtaposed cilia-cilia elongation in BBSome dependent manner in Caenorhabditis elegans
(CELL PRESS, 2025) Turan, Merve Gul; Kantarci, Hanife; Cevik, Sebiha; Kaplan, Oktay I.; 0000-0002-0935-1929; 0000-0002-8733-0920; AGÜ, Yaşam ve Doğa Bilimleri Fakültesi, Moleküler Biyoloji ve Genetik Bölümü; Turan, Merve Gul; Kantarci, Hanife; Cevik, Sebiha; Kaplan, Oktay I.
The interaction of cilia with various cellular compartments, such as axons, has emerged as a new form of cellular communication. Cilia often extend in proximity to cilia from neighboring cells. However, the mechanisms driving this process termed juxtaposed cilia-cilia elongation (JCE) remain unclear. We use fluorescence-based visualization to study the mechanisms of coordinated cilia elongation in sensory neurons of Caenorhabditis elegans. Conducting a selective gene-based screening strategy reveals that ARL-13/ARL13B and MKS-5/RPGRIP1L are essential for JCE. We demonstrate that ARL-13 modulates JCE independently of cilia length. Loss of NPHP-2/inversin along with HDAC-6 enhances the cilia misdirection phenotype of arl-13 mutants, while disruption of the BBSome complex, but not microtubule components, partially suppresses the JCE defects in arl-13 mutants. We further show changes in the phospholipid compositions in arl-13 mutants. We suggest that ARL-13 contributes to JCE, in part, through the modulation of the ciliary membrane.
The Joubert syndrome protein CEP41 is excluded from the distal segment of cilia in C. elegans
(2021) Sebiha Cevik; Oktay I Kaplan; AGÜ, Yaşam ve Doğa Bilimleri Fakültesi, Biyomühendislik Bölümü; Cevik, Sebiha; Kaplan, Oktay I.
Rare diseases are a fundamental issue in today's world, affecting more than 300 million individuals worldwide. According to data from Orphanet and OMIM, about 50-60 new conditions are added to the list of over 6,000 clinically distinct diseases each year, rendering disease diagnosis and treatment even more challenging. Ciliopathies comprise a heterogeneous category of rare diseases made up of over 35 distinct diseases, including Joubert syndrome (JBTS; OMIM 213300), that are caused by functional and structural defects in cilia. JBTS is an autosomal recessive condition characterized by a range of symptoms, including cerebellar vermis hypoplasia and poor muscle tone. There are now a total of 38 genes that cause JBTS, almost all of which encode protein products that are found in cilia and cilia-associated compartments, such as the basal body and transition zone. CEP41 is a JBTS-associated protein that is found in cilia and the basal body of mammals, but its localization in other ciliary organisms remains elusive. C. elegans is an excellent model organism for studying the molecular mechanisms of rare diseases like JBTS. We, therefore, decided to use C. elegans to identify the localization of CEP41. Our microscopy analysis revealed that CEPH-41(CEntrosomal Protein Homolog 41) not only localizes to cilia but is excluded from the distal segment of the amphid and phasmid cilia in C. elegans. Furthermore, we discovered a putative X-box motif located in the promoter of ceph-41 and the expression of ceph-41 is regulated by DAF-19, a sole Regulatory Factor X (RFX) transcription factor.
Matching variants for functional characterization of genetic variants
(Oxford University Press, 2023) Cevik,Sabiha; Zhao,Pei; Zorluer,Atiyye; Pir, Mustafa S.; Bian, Wenyin; Kaplan, Oktay I.; 0000-0002-0935-1929; AGÜ, Yaşam ve Doğa Bilimleri Fakültesi, Moleküler Biyoloji ve Genetik Bölümü; Cevik, Sabiha; Zorluer, Atiye; Pir, Mustafa S.
Rapid and low-cost sequencing, as well as computer analysis, have facilitated the diagnosis of many genetic diseases, resulting in a substantial rise in the number of disease-associated genes. However, genetic diagnosis of many disorders remains problematic due to the lack of interpretation for many genetic variants, especially missenses, the infeasibility of high-throughput experiments on mammals, and the shortcomings of computational prediction technologies. Additionally, the available mutant databases are not well-utilized. Toward this end, we used Caenorhabditis elegans mutant resources to delineate the functions of eight missense variants (V444I, V517D, E610K, L732F, E817K, H873P, R1105K, and G1205E) and two stop codons (W937stop and Q1434stop), including several matching variants (MatchVar) with human in ciliopathy associated IFT-140 (also called CHE-11)//IFT140 (intraflagellar transport protein 140). Moreover, MatchVars carrying C. elegans mutants, including IFT-140(G680S) and IFT-140(P702A) for the human (G704S) (dbSNP: rs150745099) and P726A (dbSNP: rs1057518064 and a conflicting variation) were created using CRISPR/Cas9. IFT140 is a key component of IFT complex A (IFT-A), which is involved in the retrograde transport of IFT along cilia and the entrance of G protein-coupled receptors into cilia. Functional analysis of all 10 variants revealed that P702A and W937stop, but not others phenocopied the ciliary phenotypes (short cilia, IFT accumulations, mislocalization of membrane proteins, and cilia entry of nonciliary proteins) of the IFT-140 null mutant, indicating that both P702A and W937stop are phenotypic in C. elegans. Our functional data offered experimental support for interpreting human variants, by using ready-to-use mutants carrying MatchVars and generating MatchVars with CRISPR/Cas9.
MSABrowser: dynamic and fast visualization of sequence alignments, variations and annotations
(Oxford University Press, 2021) Torun, Furkan M.; Bilgin, Halil İbrahim; Kaplan, Oktay I.; AGÜ, Mühendislik Fakültesi, Bilgisayar Mühendisliği Bölümü; Bilgin, Halil İbrahim; Torun, Furkan M.; Kaplan, Oktay I.
Sequence alignment is an excellent way to visualize the similarities and differences between DNA, RNA or protein sequences, yet it is currently difficult to jointly view sequence alignment data with genetic variations, modifications such as post-translational modifications and annotations (i.e. protein domains). Here, we present the MSABrowser tool that makes it easy to co-visualize genetic variations, modifications and annotations on the respective positions of amino acids or nucleotides in pairwise or multiple sequence alignments. MSABrowser is developed entirely in JavaScript and works on any modern web browser at any platform, including Linux, Mac OS X and Windows systems without any installation. MSABrowser is also freely available for the benefit of the scientific community.
Protocol for determining the average speed and frequency of kinesin and dynein-driven intraflagellar transport (IFT) in C. elegans
(Cell Press, 2022) Turan, Merve G.; Kantarci, Hanife; Temtek, Sadiye D.; Cakici, Onur; Cevik, Sebiha; Kaplan, Oktay I.; 0000-0002-0935-1929; 0000-0002-8733-0920; AGÜ, Yaşam ve Doğa Bilimleri Fakültesi, Moleküler Biyoloji ve Genetik Bölümü; Turan, Merve G.; Kantarcı, Hanife; Temtek, Sadiye D.; Çakıcı, Onur; Çevik, Sebiha; Kaplan, Oktay I.
Here, we present a protocol to image a fluorescent-labeled intraflagellar transport (IFT) component in Caenorhabditis elegans with fluorescence microscopy, including steps of sample preparations, in vivo live-cell imaging, and post-microscopy analysis with kymographs. This protocol breaks down all processes into three categories: (1) pre-imaging preparations, (2) preparations for the time of image acquisition, and (3) post-imaging analyses. The protocol can be applied to determine the speed and frequency of moving particles. For complete details on the use and execution of this protocol, please refer to Cevik et al. (2021).
Subcellular localization of the voltage-gated K+ channel EGL-36 , a member of the KV3 subfamily, in the ciliated sensory neurons in C. elegans
(2021) Sebiha Cevik; Oktay I Kaplan; AGÜ, Yaşam ve Doğa Bilimleri Fakültesi, Biyomühendislik Bölümü; Cevik, Sebiha; Kaplan, Oktay I.
Delineated as the first cellular organelle in 1675 by Antonie van Leeuwenhoek, cilia did not receive much attention until the 2000s, when it became apparent that cilia played a key role in the development of embryos, a variety of signaling pathways. Therefore, collective efforts by many scientists have led to the identification of many novel ciliopathy and cilia genes, while we are still far from disclosing the complete components of cilia.Here we used the ciliated sensory neurons in C. elegans as a model system that revealed the voltage-gated K+ channel EGL-36 (a member of the Shaw subfamily) as a new component associated with cilia. The confocal microscopy examination of fluorescence tagged EGL-36 together with ciliary (IFT-140) or transition zone (MKS-6) markers reveal that EGL-36 is only expressed in subsets of the ciliated sensory neurons, where it partially overlaps with the basal body signals and predominantly localizes to the periciliary membrane compartment. This expression pattern along with studies of egl-36 gain-of-function variants indicates that egl-36 is not essential for ciliogenesis in C. elegans. Our data identify the voltage-gated K+ channel EGL-36 as a new cilia-associated protein, and future studies should reveal the functional significance of EGL-36 in cilia biogenesis.