TY - JOUR A1 - Hanke-Gogokhia, Christin A1 - Frederick, Jeanne M. A1 - Zhang, Houbin A1 - Baehr, Wolfgang T1 - Binary Function of ARL3-GTP Revealed by Gene Knockouts JF - Retinal Degenerative Diseases : Mechanisms and Experimental Therapy N2 - UNC119 and PDE delta are lipid-binding proteins and are thought to form diffusible complexes with transducin-alpha and prenylated OS proteins, respectively, to mediate their trafficking to photoreceptor outer segments. Here, we investigate mechanisms of trafficking which are controlled by Arf-like protein 3 (Arl3), a small GTPase. The activity of ARL3 is regulated by a GEF (ARL13b) and a GAP (RP2). In a mouse germline knockout of RP2, ARL3-GTP is abundant as its intrinsic GTPase activity is extremely low. High levels of ARL3-GTP impair binding and trafficking of cargo to the outer segment. Germline knockout of ARL3 is embryonically lethal generating a syndromic ciliopathy-like phenotype. Retina-and rod-specific knockout of ARL3 allow to determine the precise mechanisms leading to photoreceptor degeneration. The knockouts reveal binary functions of ARL3-GTP as a key molecule in late-stage photoreceptor ciliogenesis and cargo displacement factor. KW - ARL3 KW - ARL13b KW - PDE delta KW - UNC119 KW - RP2 KW - Photoreceptor KW - Germline knockout KW - Retina disease Y1 - 2018 SN - 978-3-319-75402-4 SN - 978-3-319-75401-7 U6 - https://doi.org/10.1007/978-3-319-75402-4_39 SN - 0065-2598 SN - 2214-8019 VL - 1074 SP - 317 EP - 325 PB - Springer CY - Cham ER - TY - CHAP A1 - Hanke-Gogokhia, Christin A1 - Frederick, Jeanne M. A1 - Zhang, Houbin A1 - Baehr, Wolfgang T1 - ARL3 regulates transport of prenylated and acylated proteins to photoreceptor outer segment in mouse retina T2 - Investigative ophthalmology & visual science Y1 - 2015 SN - 0146-0404 SN - 1552-5783 VL - 56 IS - 7 PB - Association for Research in Vision and Opthalmology CY - Rockville ER - TY - JOUR A1 - Hanke-Gogokhia, Christin A1 - Wu, Zhijian A1 - Gerstner, Cecilia D. A1 - Frederick, Jeanne M. A1 - Zhang, Houbin A1 - Baehr, Wolfgang T1 - Arf-like Protein 3 (ARL3) Regulates Protein Trafficking and Ciliogenesis in Mouse Photoreceptors JF - The journal of biological chemistry N2 - Arf-like protein 3 (ARL3) is a ubiquitous small GTPase expressed in ciliated cells of plants and animals. Germline deletion of Arl3 in mice causes multiorgan ciliopathy reminiscent of Bardet-Biedl or Joubert syndromes. As photoreceptors are elegantly compartmentalized and have cilia, we probed the function of ARL3 (ADP-ribosylation factor (Arf)-like 3 protein) by generating rod photoreceptor-specific (prefix (rod)) and retina-specific (prefix (ret)) Arl3 deletions. In predegenerate (rod)Arl3(-/-) mice, lipidated phototransduction proteins showed trafficking deficiencies, consistent with the role of ARL3 as a cargo displacement factor for lipid-binding proteins. By contrast, (ret)Arl3(-/-) rods and cones expressing Cre recombinase during embryonic development formed neither connecting cilia nor outer segments and degenerated rapidly. Absence of cilia infers participation of ARL3 in ciliogenesis and axoneme formation. Ciliogenesis was rescued, and degeneration was reversed in part by subretinal injection of adeno-associated virus particles expressing ARL3-EGFP. The conditional knock-out phenotypes permitted identification of two ARL3 functions, both in the GTP-bound form as follows: one as a regulator of intraflagellar transport participating in photoreceptor ciliogenesis and the other as a cargo displacement factor transporting lipidated protein to the outer segment. Surprisingly, a farnesylated inositol polyphosphate phosphatase only trafficked from the endoplasmic reticulum to the Golgi, thereby excluding it from a role in photoreceptor cilia physiology. KW - animal model KW - gene knock-out KW - lipid-binding protein KW - photoreceptor KW - protein trafficking (Golgi) KW - retinal degeneration Y1 - 2016 U6 - https://doi.org/10.1074/jbc.M115.710954 SN - 0021-9258 SN - 1083-351X VL - 291 SP - 7142 EP - 7155 PB - American Society for Biochemistry and Molecular Biology CY - Bethesda ER - TY - JOUR A1 - Hanke-Gogokhia, Christin A1 - Zhang, Houbin A1 - Frederick, Jeanne M. A1 - Baehr, Wolfgang ED - Rickman, CB ED - LaVail, MM ED - Anderson, RE ED - Grimm, C ED - Hollyfield, J ED - Ash, J T1 - The Function of Arf-like Proteins ARL2 and ARL3 in Photoreceptors JF - Retinal Degenerative Diseases : Mechanisms and Experimental Therapy N2 - Arf-like proteins (ARLs) are ubiquitously expressed small G proteins of the RAS superfamily. In photoreceptors, ARL2 and ARL3 participate in the trafficking of lipidated membrane-associated proteins and colocalize in the inner segment with UNC119A and PDE delta. UNC119A and PDE delta are acyl-and prenyl-binding proteins, respectively, involved in trafficking of acylated (transducin-alpha subunit, nephrocystin NPHP3) and prenylated proteins (GRK1, PDE6). Germline Arl3 knockout mice do not survive beyond postnatal day 21 and display ciliary defects in multiple organs (kidney, liver and pancreas) as well as retinal degeneration. Conditional knockouts will be necessary to delineate mechanisms of protein transport in retina disease. KW - Arf-like protein 3 (ARL3) KW - Arf-like protein 2 (ARL2) KW - Phosphodiesterase delta-subunit (PDE delta) KW - unc-119 homolog (C. elegans) (UNC119A) KW - Retinitis pigmentosa protein 2 (RP2) KW - Rod photoreceptor Y1 - 2016 SN - 978-3-319-17121-0; 978-3-319-17120-3 U6 - https://doi.org/10.1007/978-3-319-17121-0_87 SN - 0065-2598 VL - 854 SP - 655 EP - 661 PB - Springer International Publishing AG CY - Cham ER - TY - JOUR A1 - Ronquillo, Cecinio C. A1 - Hanke-Gogokhia, Christin A1 - Revelo, Monica P. A1 - Frederick, Jeanne M. A1 - Jiang, Li A1 - Baehr, Wolfgang T1 - Ciliopathy-associated IQCB1/NPHP5 protein is required for mouse photoreceptor outer segment formation JF - The FASEB journal : the official journal of the Federation of American Societies for Experimental Biology N2 - Null mutations in the human IQCB1/NPHP5 (nephrocystin-5) gene that encodes NPHP5 are the most frequent cause of Senior-LOken syndrome, a ciliopathy that is characterized by Leber congenital amaurosis and nephronophthisis. We generated germline Nphp5-knockout mice by placing a -Geo gene trap in intron 4, thereby truncating NPHP5 at Leu87 and removing all known functional domains. At eye opening, Nphp5(-/-) mice exhibited absence of scotopic and photopic electroretinogram responses, a phenotype that resembles Leber congenital amaurosis. Outer segment transmembrane protein accumulation in Nphp5(-/-) endoplasmic reticulum was evident as early as postnatal day (P)6. EGFP-CETN2, a centrosome and transition zone marker, identified basal bodies in Nphp5(-/-) photoreceptors, but without fully developed transition zones. Ultrastructure of P6 and 10 Nphp5(-/-) photoreceptors revealed aberrant transition zones of reduced diameter. Nphp5(-/-) photoreceptor degeneration was complete at 1 mo of age but was delayed significantly in Nphp5(-/-);Nrl(-/-) (cone only) retina. Nphp5(-/-) mouse embryonic fibroblast developed normal cilia, and Nphp5(-/-) kidney histology at 1 yr of age showed no significant pathology. Results establish that nephrocystin-5 is essential for photoreceptor outer segment formation but is dispensable for kidney and mouse embryonic fibroblast ciliary formation. KW - Senior-LOken syndrome KW - nephronophthisis KW - Leber congenital amaurosis KW - nephrocystins Y1 - 2016 U6 - https://doi.org/10.1096/fj.201600511R SN - 0892-6638 SN - 1530-6860 VL - 30 SP - 3400 EP - 3412 PB - Federation of American Societies for Experimental Biology CY - Bethesda ER - TY - JOUR A1 - Zhang, Houbin A1 - Hanke-Gogokhia, Christin A1 - Jiang, Li A1 - Li, Xiaobo A1 - Wang, Pu A1 - Gerstner, Cecilia D. A1 - Frederick, Jeanne M. A1 - Yang, Zhenglin A1 - Baehr, Wolfgang T1 - Mistrafficking of prenylated proteins causes retinitis pigmentosa 2 JF - The FASEB journal : the official journal of the Federation of American Societies for Experimental Biology N2 - The retinitis pigmentosa 2 polypeptide (RP2) functions as a GTPase-activating protein (GAP) for ARL3 (Arf-like protein 3), a small GTPase. ARL3 is an effector of phosphodiesterase 6 Delta (PDE6D), a prenyl-binding protein and chaperone of prenylated protein in photoreceptors. Mutations in the human RP2 gene cause X-linked retinitis pigmentosa (XLRP) and cone-rod dystrophy (XL-CORD). To study mechanisms causing XLRP, we generated an RP2 knockout mouse. The RP2h(-/-) mice exhibited a slowly progressing rod-cone dystrophy simulating the human disease. RP2h(-/-) scotopic a-wave and photopic b-wave amplitudes declined at 1 mo of age and continued to decline over the next 6 mo. Prenylated PDE6 subunits and G-protein coupled receptor kinase 1 (GRK1) were unable to traffic effectively to the RP2h(-/-) outer segments. Mechanistically, absence of RP2 GAP activity increases ARL3-GTP levels, forcing PDE6D to assume a predominantly "closed" conformation that impedes binding of lipids. Lack of interaction disrupts trafficking of PDE6 and GRK1 to their destination, the photoreceptor outer segments. We propose that hyperactivity of ARL3-GTP in RP2 knockout mice and human patients with RP2 null alleles leads to XLRP resembling recessive rod-cone dystrophy. KW - rod-cone dystrophy KW - ARL3 KW - PDE6D KW - RP2 KW - XLRP Y1 - 2015 U6 - https://doi.org/10.1096/fj.14-257915 SN - 0892-6638 SN - 1530-6860 VL - 29 IS - 3 SP - 932 EP - 942 PB - Federation of American Societies for Experimental Biology CY - Bethesda ER -