Search results for "Connecting cilium"

The retinitis pigmentosa protein RP2 links pericentriolar vesicle transport between the Golgi and the primary cilium.

2010

Photoreceptors are complex ciliated sensory neurons. The basal body and periciliary ridge of photoreceptors function in association with the Golgi complex to regulate the export of proteins from the inner segment to the outer segment sensory axoneme. Here, we show that the retinitis pigmentosa protein RP2, which is a GTPase activating protein (GAP) for Arl3, localizes to the ciliary apparatus, namely the basal body and the associated centriole at the base of the photoreceptor cilium. Targeting to the ciliary base was dependent on N-terminal myristoylation. RP2 also localized to the Golgi and periciliary ridge of photoreceptors, which suggested a role for RP2 in regulating vesicle traffic an…

Identification of Novel Molecular Components of the Photoreceptor Connecting Cilium by Immunoscreens

2002

Abstract The connecting cilium of photoreceptor cells is the only intracellular link between the morphologically, functionally and biochemically different compartments of the inner and outer segments. The non-motile modified cilium plays an important role in the organization and the function of photoreceptor cells, namely in delivery and turnover of enzymes and substrates of the visual transduction cascade, and the photosensitive membranes of the outer segment. The protein components of the cilium participate in the intracellular transport through the cilium, in the outer segment disk morphogenesis and in the maintenance of discrete membrane domains. In order to identify yet unknown cytoske…

Rhodopsin transport in the membrane of the connecting cilium of mammalian photoreceptor cells

2000

The transport of the photopigment rhodopsin from the inner segment to the photosensitive outer segment of vertebrate photoreceptor cells has been one of the main remaining mysteries in photoreceptor cell biology. Because of the lack of any direct evidence for the pathway through the photoreceptor cilium, alternative extracellular pathways have been proposed. Our primary aim in the present study was to resolve rhodopsin trafficking from the inner to the outer segment. We demonstrate, predominantly by high-sensitive immunoelectron microscopy, that rhodopsin is also densely packed in the membrane of the photoreceptor connecting cilium. Present prominent labeling of rhodopsin in the ciliary mem…

Association of Whirlin with Cav1.3 (α1D) Channels in Photoreceptors, Defining a Novel Member of the Usher Protein Network

2010

Contains fulltext : 88383.pdf (Publisher’s version ) (Closed access) PURPOSE: Usher syndrome is the most common form of hereditary deaf-blindness. It is both clinically and genetically heterogeneous. The USH2D protein whirlin interacts via its PDZ domains with other Usher-associated proteins containing a C-terminal type I PDZ-binding motif. These proteins co-localize with whirlin at the region of the connecting cilium and at the synapse of photoreceptor cells. This study was undertaken to identify novel, Usher syndrome-associated, interacting partners of whirlin and thereby obtain more insights into the function of whirlin. METHODS: The database of ciliary proteins was searched for proteins…

2017

Several studies have demonstrated that the expression of odorant receptors (ORs) occurs in various tissues. These findings have served as a basis for functional studies that demonstrate the potential of ORs as drug targets for a clinical application. To the best of our knowledge, this report describes the first evaluation of the mRNA expression of ORs and the localization of OR proteins in the human retina that set a stage for subsequent functional analyses. RNA-Sequencing datasets of three individual neural retinae were generated using Next-generation sequencing and were compared to previously published but reanalyzed datasets of the peripheral and the macular human retina and to reference…

Insights into functional aspects of centrins from the structure of N-terminally extended mouse centrin 1

2006

AbstractCentrins are members of the family of Ca2+-binding EF-hand proteins. In photoreceptor cells, centrin isoform 1 is specifically localized in the non-motile cilium. This connecting cilium links the light-sensitive outer segment with the biosynthetic active inner segment of the photoreceptor cell. All intracellular exchanges between these compartments have to occur through this cilium. Three-dimensional structures of centrins from diverse organisms are known, showing that the EF-hand motifs of the N-terminal domains adopt closed conformations, while the C-terminal EF-hand motifs have open conformations. The crystal structure of an N-terminally extended mouse centrin 1 (MmCen1-L) resemb…

C21orf2 is mutated in recessive early-onset retinal dystrophy with macular staphyloma and encodes a protein that localises to the photoreceptor prima…

2015

Background/aim We have noted a phenotype of early-onset retinal dystrophy with macular staphyloma but without high myopia. The aim of this study is to report the underlying genetic mutations and the subcellular localisation of the gene product in the retina. Methods Retrospective case series (2012–2015); immunohistochemical analyses of mammalian retina for in situ protein localisation. Results All three probands were first noted to have decreased vision at 3–6 years old which worsened over time. At ages 39, 37 and 12 years old, all had similar retinal findings: dystrophic changes (retinal pigment epithelium mottling, vessel narrowing), macular staphyloma (despite only mild myopia or high hy…

SANS (USH1G) expression in developing and mature mammalian retina

2008

AbstractThe human Usher syndrome (USH) is the most common form of combined deaf-blindness. Usher type I (USH1), the most severe form, is characterized by profound congenital deafness, constant vestibular dysfunction and prepubertal-onset of retinitis pigmentosa. Five corresponding genes of the six USH1 genes have been cloned so far. The USH1G gene encodes the SANS (scaffold protein containing ankyrin repeats and SAM domain) protein which consists of protein motifs known to mediate protein–protein interactions. Recent studies indicated SANS function as a scaffold protein in the protein interactome related to USH.Here, we generated specific antibodies for SANS protein expression analyses. Our…

Centrins, gatekeepers for the light-dependent translocation of transducin through the photoreceptor cell connecting cilium

2006

Centrins are members of a highly conserved subgroup of the EF-hand superfamily of Ca(2+)-binding proteins commonly associated with centrosome-related structures. In the retina, centrins are also prominent components of the photoreceptor cell ciliary apparatus. Centrin isoforms are differentially localized at the basal body and in the lumen of the connecting cilium. All molecular exchanges between the inner and outer segments occur through this narrow connecting cilium. Ca(2+)-activated centrin isoforms bind to the visual heterotrimeric G-protein transducin via an interaction with the betagamma-subunit. Ca(2+)-dependent assemblies of centrin/G-protein complexes may regulate the transducin mo…

Evidence for Myosin VIIa-Driven Transport of Rhodopsin in the Plasma Membrane of the Photoreceptor-Connecting Cilium

2007

Defects in the gene encoding for the unconventional myosin VIIa leads to human Usher syndrome 1B, the most common form of hereditary combined blindness and deafness. To determine cellular function of myosin VIIa, we have investigated the subcellular localization of myosin VIIa in spacial relation relationship to potentially interacting proteins in mammalian photoreceptor cells. Western blot analysis of the axonemal fraction of photoreceptor cells by Western blot show that myosin VIIa and actin, as well as opsin, were present in the ciliary portion of the photoreceptors. Improved immunoelectron microscopy revealed that in mammalian photoreceptor cells, myosin VIIa was localized at the membra…