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Bassetto M, Kolesnikov AV, Lewandowski D, Kiser JZ, Halabi M, Einstein DE, Choi EH, Palczewski K, Kefalov VJ, Kiser PD. Dominant role for pigment epithelial CRALBP in supplying visual chromophore to photoreceptors. Cell Rep 2024; 43:114143. [PMID: 38676924 DOI: 10.1016/j.celrep.2024.114143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 03/22/2024] [Accepted: 04/09/2024] [Indexed: 04/29/2024] Open
Abstract
Cellular retinaldehyde-binding protein (CRALBP) supports production of 11-cis-retinaldehyde and its delivery to photoreceptors. It is found in the retinal pigment epithelium (RPE) and Müller glia (MG), but the relative functional importance of these two cellular pools is debated. Here, we report RPE- and MG-specific CRALBP knockout (KO) mice and examine their photoreceptor and visual cycle function. Bulk visual chromophore regeneration in RPE-KO mice is 15-fold slower than in controls, accounting for their delayed rod dark adaptation and protection against retinal phototoxicity, whereas MG-KO mice have normal bulk visual chromophore regeneration and retinal light damage susceptibility. Cone pigment regeneration is significantly impaired in RPE-KO mice but mildly affected in MG-KO mice, disclosing an unexpectedly strong reliance of cone photoreceptors on the RPE-based visual cycle. These data reveal a dominant role for RPE-CRALBP in supporting rod and cone function and highlight the importance of RPE cell targeting for CRALBP gene therapies.
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Affiliation(s)
- Marco Bassetto
- Department of Physiology & Biophysics, University of California Irvine, Irvine, CA 92697, USA; Research Service, Tibor Rubin VA Long Beach Medical Center, Long Beach, CA 90822, USA; Center for Translational Vision Research, Gavin Herbert Eye Institute, Department of Ophthalmology, University of California Irvine, Irvine, CA 92697, USA
| | - Alexander V Kolesnikov
- Center for Translational Vision Research, Gavin Herbert Eye Institute, Department of Ophthalmology, University of California Irvine, Irvine, CA 92697, USA
| | - Dominik Lewandowski
- Center for Translational Vision Research, Gavin Herbert Eye Institute, Department of Ophthalmology, University of California Irvine, Irvine, CA 92697, USA
| | - Jianying Z Kiser
- Department of Physiology & Biophysics, University of California Irvine, Irvine, CA 92697, USA; Center for Translational Vision Research, Gavin Herbert Eye Institute, Department of Ophthalmology, University of California Irvine, Irvine, CA 92697, USA
| | - Maximilian Halabi
- Department of Physiology & Biophysics, University of California Irvine, Irvine, CA 92697, USA
| | - David E Einstein
- Department of Physiology & Biophysics, University of California Irvine, Irvine, CA 92697, USA; Research Service, Tibor Rubin VA Long Beach Medical Center, Long Beach, CA 90822, USA
| | - Elliot H Choi
- Center for Translational Vision Research, Gavin Herbert Eye Institute, Department of Ophthalmology, University of California Irvine, Irvine, CA 92697, USA
| | - Krzysztof Palczewski
- Department of Physiology & Biophysics, University of California Irvine, Irvine, CA 92697, USA; Center for Translational Vision Research, Gavin Herbert Eye Institute, Department of Ophthalmology, University of California Irvine, Irvine, CA 92697, USA; Department of Chemistry, University of California Irvine, Irvine, CA 92697, USA; Department of Molecular Biology and Biochemistry, University of California Irvine, Irvine, CA 92697, USA
| | - Vladimir J Kefalov
- Department of Physiology & Biophysics, University of California Irvine, Irvine, CA 92697, USA; Center for Translational Vision Research, Gavin Herbert Eye Institute, Department of Ophthalmology, University of California Irvine, Irvine, CA 92697, USA
| | - Philip D Kiser
- Department of Physiology & Biophysics, University of California Irvine, Irvine, CA 92697, USA; Research Service, Tibor Rubin VA Long Beach Medical Center, Long Beach, CA 90822, USA; Center for Translational Vision Research, Gavin Herbert Eye Institute, Department of Ophthalmology, University of California Irvine, Irvine, CA 92697, USA; Department of Clinical Pharmacy Practice, University of California Irvine, Irvine, CA 92697, USA.
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Kolesnikov AV, Murphy DP, Corbo JC, Kefalov VJ. Germline knockout of Nr2e3 protects photoreceptors in three distinct mouse models of retinal degeneration. Proc Natl Acad Sci U S A 2024; 121:e2316118121. [PMID: 38442152 PMCID: PMC10945761 DOI: 10.1073/pnas.2316118121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Accepted: 01/17/2024] [Indexed: 03/07/2024] Open
Abstract
Retinitis pigmentosa (RP) is a common form of retinal dystrophy that can be caused by mutations in any one of dozens of rod photoreceptor genes. The genetic heterogeneity of RP represents a significant challenge for the development of effective therapies. Here, we present evidence for a potential gene-independent therapeutic strategy based on targeting Nr2e3, a transcription factor required for the normal differentiation of rod photoreceptors. Nr2e3 knockout results in hybrid rod photoreceptors that express the full complement of rod genes, but also a subset of cone genes. We show that germline deletion of Nr2e3 potently protects rods in three mechanistically diverse mouse models of retinal degeneration caused by bright-light exposure (light damage), structural deficiency (rhodopsin-deficient Rho-/- mice), or abnormal phototransduction (phosphodiesterase-deficient rd10 mice). Nr2e3 knockout confers strong neuroprotective effects on rods without adverse effects on their gene expression, structure, or function. Furthermore, in all three degeneration models, prolongation of rod survival by Nr2e3 knockout leads to lasting preservation of cone morphology and function. These findings raise the possibility that upregulation of one or more cone genes in Nr2e3-deficient rods may be responsible for the neuroprotective effects we observe.
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Affiliation(s)
- Alexander V. Kolesnikov
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, CA92697
| | - Daniel P. Murphy
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO63110
| | - Joseph C. Corbo
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO63110
| | - Vladimir J. Kefalov
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, CA92697
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Tworak A, Kolesnikov AV, Hong JD, Choi EH, Luu JC, Palczewska G, Dong Z, Lewandowski D, Brooks MJ, Campello L, Swaroop A, Kiser PD, Kefalov VJ, Palczewski K. Rapid RGR-dependent visual pigment recycling is mediated by the RPE and specialized Müller glia. Cell Rep 2023; 42:112982. [PMID: 37585292 PMCID: PMC10530494 DOI: 10.1016/j.celrep.2023.112982] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 06/14/2023] [Accepted: 07/29/2023] [Indexed: 08/18/2023] Open
Abstract
In daylight, demand for visual chromophore (11-cis-retinal) exceeds supply by the classical visual cycle. This shortfall is compensated, in part, by the retinal G-protein-coupled receptor (RGR) photoisomerase, which is expressed in both the retinal pigment epithelium (RPE) and in Müller cells. The relative contributions of these two cellular pools of RGR to the maintenance of photoreceptor light responses are not known. Here, we use a cell-specific gene reactivation approach to elucidate the kinetics of RGR-mediated recovery of photoreceptor responses following light exposure. Electroretinographic measurements in mice with RGR expression limited to either cell type reveal that the RPE and a specialized subset of Müller glia contribute both to scotopic and photopic function. We demonstrate that 11-cis-retinal formed through photoisomerization is rapidly hydrolyzed, consistent with its role in a rapid visual pigment regeneration process. Our study shows that RGR provides a pan-retinal sink for all-trans-retinal released under sustained light conditions and supports rapid chromophore regeneration through the photic visual cycle.
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Affiliation(s)
- Aleksander Tworak
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA.
| | - Alexander V Kolesnikov
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA
| | - John D Hong
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA
| | - Elliot H Choi
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA
| | - Jennings C Luu
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA; Department of Pharmacology, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Grazyna Palczewska
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA; Polgenix, Inc., Department of Medical Devices, Cleveland, OH 44106, USA
| | - Zhiqian Dong
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA
| | - Dominik Lewandowski
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA
| | - Matthew J Brooks
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Laura Campello
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Anand Swaroop
- Neurobiology, Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Philip D Kiser
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA; Department of Physiology & Biophysics, University of California, Irvine, Irvine, CA 92697, USA; Department of Clinical Pharmacy Practice, University of California, Irvine, Irvine, CA 92697, USA; Research Service, VA Long Beach Healthcare System, Long Beach, CA 90822, USA
| | - Vladimir J Kefalov
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA; Department of Physiology & Biophysics, University of California, Irvine, Irvine, CA 92697, USA
| | - Krzysztof Palczewski
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA 92697, USA; Department of Physiology & Biophysics, University of California, Irvine, Irvine, CA 92697, USA; Department of Chemistry, University of California, Irvine, Irvine, CA 92697, USA; Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA 92697, USA.
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Poria D, Kolesnikov AV, Lee TJ, Salom D, Palczewski K, Kefalov VJ. Investigating the Role of Rhodopsin F45L Mutation in Mouse Rod Photoreceptor Signaling and Survival. eNeuro 2023; 10:ENEURO.0330-22.2023. [PMID: 36823167 PMCID: PMC9997694 DOI: 10.1523/eneuro.0330-22.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 01/16/2023] [Accepted: 01/24/2023] [Indexed: 02/25/2023] Open
Abstract
Rhodopsin is the critical receptor molecule which enables vertebrate rod photoreceptor cells to detect a single photon of light and initiate a cascade of molecular events leading to visual perception. Recently, it has been suggested that the F45L mutation in the transmembrane helix of rhodopsin disrupts its dimerization in vitro To determine whether this mutation of rhodopsin affects its signaling properties in vivo, we generated knock-in mice expressing the rhodopsin F45L mutant. We then examined the function of rods in the mutant mice versus wild-type controls, using in vivo electroretinography and transretinal and single cell suction recordings, combined with morphologic analysis and spectrophotometry. Although we did not evaluate the effect of the F45L mutation on the state of dimerization of the rhodopsin in vivo, our results revealed that F45L-mutant mice exhibit normal retinal morphology, normal rod responses as measured both in vivo and ex vivo, and normal rod dark adaptation. We conclude that the F45L mutation does not affect the signaling properties of rhodopsin in its natural setting.
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Affiliation(s)
- Deepak Poria
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, CA 92697
| | - Alexander V Kolesnikov
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, CA 92697
| | - Tae Jun Lee
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO 63110
| | - David Salom
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, CA 92697
| | - Krzysztof Palczewski
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, CA 92697
- Department of Chemistry, University of California, Irvine, CA 92697
- Department of Physiology and Biophysics, University of California, Irvine, CA 92697
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697
| | - Vladimir J Kefalov
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, CA 92697
- Department of Physiology and Biophysics, University of California, Irvine, CA 92697
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Kolesnikov AV, Lobysheva E, Gnana-Prakasam JP, Kefalov VJ, Kisselev OG. Regulation of rod photoreceptor function by farnesylated G-protein γ-subunits. PLoS One 2022; 17:e0272506. [PMID: 35939447 PMCID: PMC9359561 DOI: 10.1371/journal.pone.0272506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 07/20/2022] [Indexed: 11/19/2022] Open
Abstract
Heterotrimeric G-protein transducin, Gt, is a key signal transducer and amplifier in retinal rod and cone photoreceptor cells. Despite similar subunit composition, close amino acid identity, and identical posttranslational farnesylation of their Gγ subunits, rods and cones rely on unique Gγ1 (Gngt1) and Gγc (Gngt2) isoforms, respectively. The only other farnesylated G-protein γ-subunit, Gγ11 (Gng11), is expressed in multiple tissues but not retina. To determine whether Gγ1 regulates uniquely rod phototransduction, we generated transgenic rods expressing Gγ1, Gγc, or Gγ11 in Gγ1-deficient mice and analyzed their properties. Immunohistochemistry and Western blotting demonstrated the robust expression of each transgenic Gγ in rod cells and restoration of Gαt1 expression, which is greatly reduced in Gγ1-deficient rods. Electroretinography showed restoration of visual function in all three transgenic Gγ1-deficient lines. Recordings from individual transgenic rods showed that photosensitivity impaired in Gγ1-deficient rods was also fully restored. In all dark-adapted transgenic lines, Gαt1 was targeted to the outer segments, reversing its diffuse localization found in Gγ1-deficient rods. Bright illumination triggered Gαt1 translocation from the rod outer to inner segments in all three transgenic strains. However, Gαt1 translocation in Gγ11 transgenic mice occurred at significantly dimmer background light. Consistent with this, transretinal ERG recordings revealed gradual response recovery in moderate background illumination in Gγ11 transgenic mice but not in Gγ1 controls. Thus, while farnesylated Gγ subunits are functionally active and largely interchangeable in supporting rod phototransduction, replacement of retina-specific Gγ isoforms by the ubiquitous Gγ11 affects the ability of rods to adapt to background light.
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Affiliation(s)
- Alexander V. Kolesnikov
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, CA, United States of America
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Elena Lobysheva
- Department of Ophthalmology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Jaya P. Gnana-Prakasam
- Department of Ophthalmology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
| | - Vladimir J. Kefalov
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, CA, United States of America
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Physiology and Biophysics, University of California, Irvine, CA, United States of America
| | - Oleg G. Kisselev
- Department of Ophthalmology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Saint Louis, Missouri, United States of America
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Kolesnikov AV, Luu J, Jin H, Palczewski K, Kefalov VJ. Deletion of Protein Phosphatase 2A Accelerates Retinal Degeneration in GRK1- and Arr1-Deficient Mice. Invest Ophthalmol Vis Sci 2022; 63:18. [PMID: 35861670 PMCID: PMC9315073 DOI: 10.1167/iovs.63.8.18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Light detection in retinal rod photoreceptors is initiated by activation of the visual pigment rhodopsin. A critical, yet often-overlooked, step enabling efficient perception of light is rhodopsin dephosphorylation mediated by protein phosphatase 2A (PP2A). PP2A deficiency has been reported to impair rhodopsin regeneration after phosphorylation by G protein receptor kinase 1 (GRK1) and binding of arrestin (Arr1), thereby delaying rod dark adaptation. However, its effects on the viability of photoreceptors in the absence of GRK1 and Arr1 remain unclear. Here, we investigated the effects of PP2A deficiency in the absence of GRK1 or Arr1, both of which have been implicated in Oguchi disease, a form of night blindness. Methods Rod-specific mice lacking the predominant catalytic Cα-subunit of PP2A were crossed with the Grk1−/− or Arr1−/− strains to obtain double knockout lines. Rod photoreceptor viability was analyzed in histological cross-sections of the retina stained with hematoxylin and eosin, and rod function was evaluated by ex vivo electroretinography. Results PP2A deficiency alone did not impair photoreceptor viability up to 12 months of age. Retinal degeneration was more pronounced in rods lacking GRK1 compared to rods lacking Arr1, and degeneration was accelerated in both Grk1−/− or Arr1−/− strains where PP2A was also deleted. In Arr1−/− mice, rod maximal photoresponse amplitudes were reduced by 80% at 3 months, and this diminution was enhanced further with concomitant PP2A deficiency. Conclusions These results suggest that although PP2A is not required for the survival of rods, its deletion accelerates the degeneration induced by the absence of either GRK1 or Arr1.
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Affiliation(s)
- Alexander V Kolesnikov
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, California, United States
| | - Jennings Luu
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, California, United States.,Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States
| | - Hui Jin
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States
| | - Krzysztof Palczewski
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, California, United States.,Department of Physiology & Biophysics, University of California, Irvine, California, United States.,Department of Chemistry, University of California, Irvine, California, United States.,Department of Molecular Biology and Biochemistry, University of California, Irvine, California, United States
| | - Vladimir J Kefalov
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, California, United States.,Department of Physiology & Biophysics, University of California, Irvine, California, United States
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Widjaja-Adhi MAK, Kolesnikov AV, Vasudevan S, Park PSH, Kefalov VJ, Golczak M. Acyl-CoA:wax alcohol acyltransferase 2 modulates the cone visual cycle in mouse retina. FASEB J 2022; 36:e22390. [PMID: 35665537 DOI: 10.1096/fj.202101855rrr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 05/12/2022] [Accepted: 05/23/2022] [Indexed: 11/11/2022]
Abstract
The daylight and color vision of diurnal vertebrates depends on cone photoreceptors. The capability of cones to operate and respond to changes in light brightness even under high illumination is attributed to their fast rate of recovery to the ground photosensitive state. This process requires the rapid replenishing of photoisomerized visual chromophore (11-cis-retinal) to regenerate cone visual pigments. Recently, several gene candidates have been proposed to contribute to the cone-specific retinoid metabolism, including acyl-CoA wax alcohol acyltransferase 2 (AWAT2, aka MFAT). Here, we evaluated the role of AWAT2 in the regeneration of visual chromophore by the phenotypic characterization of Awat2-/- mice. The global absence of AWAT2 enzymatic activity did not affect gross retinal morphology or the rate of visual chromophore regeneration by the canonical RPE65-dependent visual cycle. Analysis of Awat2 expression indicated the presence of the enzyme throughout the murine retina, including the retinal pigment epithelium (RPE) and Müller cells. Electrophysiological recordings revealed reduced maximal rod and cone dark-adapted responses in AWAT2-deficient mice compared to control mice. While rod dark adaptation was not affected by the lack of AWAT2, M-cone dark adaptation both in isolated retina and in vivo was significantly suppressed. Altogether, these results indicate that while AWAT2 is not required for the normal operation of the canonical visual cycle, it is a functional component of the cone-specific visual chromophore regenerative pathway.
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Affiliation(s)
| | - Alexander V Kolesnikov
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, California, USA
| | - Sreelakshmi Vasudevan
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio, USA
| | - Paul S-H Park
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio, USA
| | - Vladimir J Kefalov
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, California, USA.,Department of Physiology and Biophysics, University of California, Irvine, California, USA
| | - Marcin Golczak
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA.,Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
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Kalinina AA, Kolesnikov AV, Kozyr AV, Kulikova NL, Zamkova MA, Kazansky DB, Khromykh LM. Preparative Production and Purification of Recombinant Human Cyclophilin A. Biochemistry (Mosc) 2022; 87:259-268. [PMID: 35526853 DOI: 10.1134/s0006297922030063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 02/15/2022] [Accepted: 02/15/2022] [Indexed: 06/14/2023]
Abstract
In this work, we developed the method of preparative production of recombinant human cyclophilin A (rhCypA) in Escherichia coli. The full-length cDNA encoding the gene of human CypA (CYPA) was amplified by RT-PCR from the total RNA of human T cell lymphoma Jurkat. The nucleotide sequence of CYPA was optimized to provide highly effective translation in E. coli. Recombinant CYPA DNA was cloned into the pET22b(+) vector, and the resulted expression plasmid was used to transform E. coli strain BL21(DE3)Gold. The recombinant producer strain of E. coli produced soluble rhCypA in the bacterial cytoplasm. The synthesis efficiency of rhCypA was up to 50% of the total cell protein allowing to produce rhCypA in the amount of 1 g per liter of the culture. We also developed the method for rhCypA purification, consisting of a single-step tandem anion exchange chromatography on DEAE- and Q-Sepharose columns. The protein purity was 95% according to electrophoresis (SDS-PAGE), and its contamination with endotoxin did not exceed 0.05 ng per 1 mg of the protein that met the requirements of European pharmacopoeia for injectable preparations. The produced recombinant protein exhibited functional features of native CypA, i.e., isomerase activity and chemokine activity as assessed by stimulation of migration of mouse bone marrow hematopoietic stem cells in vivo. The generated producer strain of E. coli is a super-producer and could be used for large-scale experimental studies of rhCypA and in its preclinical and clinical trials as a drug.
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Affiliation(s)
- Anastasiia A Kalinina
- N. N. Blokhin National Medical Research Center of Oncology, the Ministry of Health of the Russian Federation, Moscow, 115478, Russia
| | - Alexander V Kolesnikov
- State Research Center of Applied Microbiology and Biotechnology, Obolensk, Moscow Region, 142279, Russia
| | - Arina V Kozyr
- State Research Center of Applied Microbiology and Biotechnology, Obolensk, Moscow Region, 142279, Russia
| | - Natalia L Kulikova
- Institute of Immunological Engineering, Lyubuchany, Moscow Region, 142380, Russia
| | - Maria A Zamkova
- N. N. Blokhin National Medical Research Center of Oncology, the Ministry of Health of the Russian Federation, Moscow, 115478, Russia
| | - Dmitry B Kazansky
- N. N. Blokhin National Medical Research Center of Oncology, the Ministry of Health of the Russian Federation, Moscow, 115478, Russia
| | - Ludmila M Khromykh
- N. N. Blokhin National Medical Research Center of Oncology, the Ministry of Health of the Russian Federation, Moscow, 115478, Russia.
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Laradji A, Karakocak BB, Kolesnikov AV, Kefalov VJ, Ravi N. Hyaluronic Acid-Based Gold Nanoparticles for the Topical Delivery of Therapeutics to the Retina and the Retinal Pigment Epithelium. Polymers (Basel) 2021; 13:polym13193324. [PMID: 34641139 PMCID: PMC8512139 DOI: 10.3390/polym13193324] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 09/20/2021] [Accepted: 09/23/2021] [Indexed: 12/13/2022] Open
Abstract
The ocular immune privilege is a phenomenon brought about by anatomical and physiological barriers to shield the eye from immune and inflammation responses. While this phenomenon is beneficial for eyes protection, it is, at the same time, a hindrance for drug delivery to the posterior segment of the eye to treat retinal diseases. Some ocular barriers can be bypassed by intravitreal injections, but these are associated with several side effects and patient noncompliance, especially when frequent injections are required. As an alternative, applying drugs as an eye drop is preferred due to the safety and ease. This study investigated the possible use of topically-applied hyaluronic acid-coated gold nanoparticles as drug delivery vehicles to the back of the eye. The coated gold nanoparticles were topically applied to mouse eyes, and results were compared to topically applied uncoated gold nanoparticles and phosphate-buffered saline (PBS) solution. Retina sections from these mice were then analyzed using fluorescence microscopy, inductively coupled plasma mass spectrometry (ICP-MS), and transmission electron microscopy (TEM). All characterization techniques used in this study suggest that hyaluronic acid-coated gold nanoparticles have higher distribution in the posterior segment of the eye than uncoated gold nanoparticles. Electroretinogram (ERG) analysis revealed that the visual function of mice receiving the coated gold nanoparticles was not affected, and these nanoparticles can, therefore, be applied safely. Together, our results suggest that hyaluronic acid-coated gold nanoparticles constitute potential drug delivery vehicles to the retina when applied noninvasively as an eye drop.
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Affiliation(s)
- Amine Laradji
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA; (A.L.); (B.B.K.)
- Department of Veterans Affairs, St. Louis Medical Center, St. Louis, MO 63106, USA
| | - Bedia B. Karakocak
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA; (A.L.); (B.B.K.)
- Department of Veterans Affairs, St. Louis Medical Center, St. Louis, MO 63106, USA
| | - Alexander V. Kolesnikov
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, CA 92697, USA; (A.V.K.); (V.J.K.)
| | - Vladimir J. Kefalov
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, CA 92697, USA; (A.V.K.); (V.J.K.)
- Department of Physiology and Biophysics, University of California, Irvine, CA 92697, USA
| | - Nathan Ravi
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA; (A.L.); (B.B.K.)
- Department of Veterans Affairs, St. Louis Medical Center, St. Louis, MO 63106, USA
- Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, MO 63110, USA
- Correspondence:
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10
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Laradji AM, Kolesnikov AV, Karakoçak BB, Kefalov VJ, Ravi N. Redox-Responsive Hyaluronic Acid-Based Nanogels for the Topical Delivery of the Visual Chromophore to Retinal Photoreceptors. ACS Omega 2021; 6:6172-6184. [PMID: 33718708 PMCID: PMC7948240 DOI: 10.1021/acsomega.0c05535] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 02/04/2021] [Indexed: 05/08/2023]
Abstract
Delivering therapeutics to the posterior segment of the eye is challenging due to various anatomical and physical barriers. While significant improvements have been realized by introducing direct injections to diseased sites, these approaches come with potential side effects that can range from simple inflammation to severe retinal damage. The topical instillation of drugs remains a safer and preferred alternative for patients' compliance. Here, we report the synthesis of penetratin-complexed, redox-responsive hyaluronic acid-based nanogels for the triggered release and delivery of therapeutics to the posterior part of the eye via topical application. The synthesized nanogels were shown to release their load only when exposed to a reducing environment, similar to the cytoplasm. As a model drug, visual chromophore analog, 9-cis-retinal, was loaded into nanogels and efficiently delivered to the mouse retina's photoreceptors when applied topically. Electroretinogram measurements showed a partial recovery of photoreceptor function in all treated eyes versus untreated controls. To the best of our knowledge, this report constitutes the first attempt to use a topically applied triggered-release drug delivery system to target the pigmented layer of the retina, in addition to the first attempt to deliver the visual chromophore topically.
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Affiliation(s)
- Amine M. Laradji
- Department
of Ophthalmology and Visual Sciences, Washington
University School of Medicine, St. Louis, Missouri 63110, United States
- Department
of Veterans Affairs, St. Louis Medical Center, St. Louis, Missouri 63106, United States
| | - Alexander V. Kolesnikov
- Department
of Ophthalmology and Visual Sciences, Washington
University School of Medicine, St. Louis, Missouri 63110, United States
| | - Bedia B. Karakoçak
- Department
of Ophthalmology and Visual Sciences, Washington
University School of Medicine, St. Louis, Missouri 63110, United States
- Department
of Veterans Affairs, St. Louis Medical Center, St. Louis, Missouri 63106, United States
| | - Vladimir J. Kefalov
- Department
of Ophthalmology and Visual Sciences, Washington
University School of Medicine, St. Louis, Missouri 63110, United States
| | - Nathan Ravi
- Department
of Ophthalmology and Visual Sciences, Washington
University School of Medicine, St. Louis, Missouri 63110, United States
- Department
of Veterans Affairs, St. Louis Medical Center, St. Louis, Missouri 63106, United States
- Department
of Energy, Environmental, and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63110, United States
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11
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Kolesnikov AV, Kiser PD, Palczewski K, Kefalov VJ. Function of mammalian M-cones depends on the level of CRALBP in Müller cells. J Gen Physiol 2021; 153:211551. [PMID: 33216847 PMCID: PMC7685772 DOI: 10.1085/jgp.202012675] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 09/16/2020] [Accepted: 10/27/2020] [Indexed: 12/24/2022] Open
Abstract
Cone photoreceptors mediate daytime vision in vertebrates. The rapid and efficient regeneration of their visual pigments following photoactivation is critical for the cones to remain photoresponsive in bright and rapidly changing light conditions. Cone pigment regeneration depends on the recycling of visual chromophore, which takes place via the canonical visual cycle in the retinal pigment epithelium (RPE) and the Müller cell-driven intraretinal visual cycle. The molecular mechanisms that enable the neural retina to regenerate visual chromophore for cones have not been fully elucidated. However, one known component of the two visual cycles is the cellular retinaldehyde-binding protein (CRALBP), which is expressed both in the RPE and in Müller cells. To understand the significance of CRALBP in cone pigment regeneration, we examined the function of cones in mice heterozygous for Rlbp1, the gene encoding CRALBP. We found that CRALBP expression was reduced by ∼50% in both the RPE and retina of Rlbp1+/- mice. Electroretinography (ERG) showed that the dark adaptation of rods and cones is unaltered in Rlbp1+/- mice, indicating a normal RPE visual cycle. However, pharmacologic blockade of the RPE visual cycle revealed suppressed cone dark adaptation in Rlbp1+/- mice in comparison with controls. We conclude that the expression level of CRALPB specifically in the Müller cells modulates the efficiency of the retina visual cycle. Finally, blocking the RPE visual cycle also suppressed further cone dark adaptation in Rlbp1-/- mice, revealing a shunt in the classical RPE visual cycle that bypasses CRALBP and allows partial but unexpectedly rapid cone dark adaptation.
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Affiliation(s)
- Alexander V Kolesnikov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO
| | - Philip D Kiser
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA.,Department of Ophthalmology, Gavin Herbert Eye Institute, Center for Translation Vision Research, School of Medicine, University of California, Irvine, Irvine, CA.,Research Service, VA Long Beach Healthcare System, Long Beach, CA
| | - Krzysztof Palczewski
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA.,Department of Ophthalmology, Gavin Herbert Eye Institute, Center for Translation Vision Research, School of Medicine, University of California, Irvine, Irvine, CA.,Department of Chemistry, School of Medicine, University of California, Irvine, Irvine, CA
| | - Vladimir J Kefalov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO
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12
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Thebeau C, Zhang S, Kolesnikov AV, Kefalov VJ, Semenkovich CF, Rajagopal R. Light deprivation reduces the severity of experimental diabetic retinopathy. Neurobiol Dis 2020; 137:104754. [PMID: 31978605 DOI: 10.1016/j.nbd.2020.104754] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 01/13/2020] [Accepted: 01/20/2020] [Indexed: 12/30/2022] Open
Abstract
Illumination of the retina is a major determinant of energy expenditure by its neurons. However, it remains unclear whether light exposure significantly contributes to the pathophysiology of common retinal disease. Driven by the premise that light exposure reduces the metabolic demand of the retina, recent clinical trials failed to demonstrate a benefit for constant illumination in the treatment of diabetic retinopathy. Here, we instead ask whether light deprivation or blockade of visual transduction could modulate the severity of this common cause of blindness. We randomized adult mice with two different models of diabetic retinopathy to 1-3 months of complete dark housing. Unexpectedly, we find that diabetic mice exposed to short or prolonged light deprivation have reduced diabetes-induced retinal pathology, using measures of visual function, compared to control animals in standard lighting conditions. To corroborate these results, we performed assays of retinal vascular health in diabetic Gnat1-/- and Rpe65-/- mice, which lack phototransduction. Both mutants displayed less diabetes-associated retinal vascular disease compared to respective wild-type controls. Collectively, these results suggest that light-induced visual transduction promotes the development of diabetic retinopathy and implicate photoreceptors as an early source of visual pathology in diabetes.
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Affiliation(s)
- Christina Thebeau
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Sheng Zhang
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Alexander V Kolesnikov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Vladimir J Kefalov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Clay F Semenkovich
- Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, Saint Louis, MO 63110, USA; Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Rithwick Rajagopal
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO 63110, USA.
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13
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Kolesnikov AV, Chrispell JD, Osawa S, Kefalov VJ, Weiss ER. Phosphorylation at Serine 21 in G protein-coupled receptor kinase 1 (GRK1) is required for normal kinetics of dark adaption in rod but not cone photoreceptors. FASEB J 2019; 34:2677-2690. [PMID: 31908030 DOI: 10.1096/fj.201902535r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 11/25/2019] [Accepted: 12/05/2019] [Indexed: 12/22/2022]
Abstract
Timely recovery of the light response in photoreceptors requires efficient inactivation of photoactivated rhodopsin. This process is initiated by phosphorylation of its carboxyl terminus by G protein-coupled receptor kinase 1 (GRK1). Previously, we showed that GRK1 is phosphorylated in the dark at Ser21 in a cAMP-dependent manner and dephosphorylated in the light. Results in vitro indicate that dephosphorylation of Ser21 increases GRK1 activity, leading to increased phosphorylation of rhodopsin. This creates the possibility of light-dependent regulation of GRK1 activity and its efficiency in inactivating the visual pigment. To address the functional role of GRK1 phosphorylation in rods and cones in vivo, we generated mutant mice in which Ser21 is substituted with alanine (GRK1-S21A), preventing dark-dependent phosphorylation of GRK1. GRK1-S21A mice had normal retinal morphology, without evidence of degeneration. The function of dark-adapted GRK1-S21A rods and cones was also unaffected, as demonstrated by the normal amplitude and kinetics of their responses obtained by ex vivo and in vivo ERG recordings. In contrast, rod dark adaptation following exposure to bright bleaching light was significantly delayed in GRK1-S21A mice, suggesting that the higher activity of this kinase results in enhanced rhodopsin phosphorylation and therefore delays its regeneration. In contrast, dark adaptation of cones was unaffected by the S21A mutation. Taken together, these data suggest that rhodopsin phosphorylation/dephosphorylation modulates the recovery of rhodopsin to the ground state and rod dark adaptation. They also reveal a novel role for cAMP-dependent phosphorylation of GRK1 in regulating the dark adaptation of rod but not cone photoreceptors.
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Affiliation(s)
- Alexander V Kolesnikov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO, USA
| | - Jared D Chrispell
- Department of Cell Biology and Physiology, The University of North Carolina, Lineberger Comprehensive Cancer Center, Chapel Hill, NC, USA
| | - Shoji Osawa
- Department of Cell Biology and Physiology, The University of North Carolina, Lineberger Comprehensive Cancer Center, Chapel Hill, NC, USA
| | - Vladimir J Kefalov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO, USA
| | - Ellen R Weiss
- Department of Cell Biology and Physiology, The University of North Carolina, Lineberger Comprehensive Cancer Center, Chapel Hill, NC, USA
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14
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Gospe SM, Travis AM, Kolesnikov AV, Klingeborn M, Wang L, Kefalov VJ, Arshavsky VY. Photoreceptors in a mouse model of Leigh syndrome are capable of normal light-evoked signaling. J Biol Chem 2019; 294:12432-12443. [PMID: 31248988 DOI: 10.1074/jbc.ra119.007945] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 06/12/2019] [Indexed: 11/06/2022] Open
Abstract
Mitochondrial dysfunction is an important cause of heritable vision loss. Mutations affecting mitochondrial bioenergetics may lead to isolated vision loss or life-threatening systemic disease, depending on a mutation's severity. Primary optic nerve atrophy resulting from death of retinal ganglion cells is the most prominent ocular manifestation of mitochondrial disease. However, dysfunction of other retinal cell types has also been described, sometimes leading to a loss of photoreceptors and retinal pigment epithelium that manifests clinically as pigmentary retinopathy. A popular mouse model of mitochondrial disease that lacks NADH:ubiquinone oxidoreductase subunit S4 (NDUFS4), a subunit of mitochondrial complex I, phenocopies many traits of the human disease Leigh syndrome, including the development of optic atrophy. It has also been reported that ndufs4 -/- mice display diminished light responses at the level of photoreceptors or bipolar cells. By conducting electroretinography (ERG) recordings in live ndufs4 -/- mice, we now demonstrate that this defect occurs at the level of retinal photoreceptors. We found that this deficit does not arise from retinal developmental anomalies, photoreceptor degeneration, or impaired regeneration of visual pigment. Strikingly, the impairment of ndufs4 -/- photoreceptor function was not observed in ex vivo ERG recordings from isolated retinas, indicating that photoreceptors with complex I deficiency are intrinsically capable of normal signaling. The difference in electrophysiological phenotypes in vivo and ex vivo suggests that the energy deprivation associated with severe mitochondrial impairment in the outer retina renders ndufs4 -/- photoreceptors unable to maintain the homeostatic conditions required to operate at their normal capacity.
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Affiliation(s)
- Sidney M Gospe
- Department of Ophthalmology, Duke University, Durham, North Carolina 27710.
| | - Amanda M Travis
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina 27710
| | - Alexander V Kolesnikov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, Missouri 63110
| | - Mikael Klingeborn
- Department of Ophthalmology, Duke University, Durham, North Carolina 27710
| | - Luyu Wang
- Department of Ophthalmology, Duke University, Durham, North Carolina 27710
| | - Vladimir J Kefalov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, Missouri 63110
| | - Vadim Y Arshavsky
- Department of Ophthalmology, Duke University, Durham, North Carolina 27710; Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina 27710
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15
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Kiser PD, Kolesnikov AV, Kiser JZ, Dong Z, Chaurasia B, Wang L, Summers SA, Hoang T, Blackshaw S, Peachey NS, Kefalov VJ, Palczewski K. Conditional deletion of Des1 in the mouse retina does not impair the visual cycle in cones. FASEB J 2019; 33:5782-5792. [PMID: 30645148 PMCID: PMC6436658 DOI: 10.1096/fj.201802493r] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Cone photoreceptors are essential for vision under moderate to high illuminance and allow color discrimination. Their fast dark adaptation rate and resistance to saturation are believed to depend in part on an intraretinal visual cycle that supplies 11-cis-retinaldehyde to cone opsins. Candidate enzymes of this pathway have been reported, but their physiologic contribution to cone photoresponses remains unknown. Here, we evaluate the role of a candidate retinol isomerase of this pathway, sphingolipid δ4 desaturase 1 (Des1). Single-cell RNA sequencing analysis revealed Des1 expression not only in Müller glia but also throughout the retina and in the retinal pigment epithelium. We assessed cone functional dependence on Müller cell–expressed Des1 through a conditional knockout approach. Floxed Des1 mice, on a guanine nucleotide-binding protein subunit α transducin 1 knockout (Gnat1−/−) background to allow isolated recording of cone-driven photoresponses, were bred with platelet-derived growth factor receptor α (Pdgfrα)-Cre mice to delete Des1 in Müller cells. Conditional knockout of Des1 expression, as shown by tissue-selective Des1 gene recombination and reduced Des1 catalytic activity, caused no gross changes in the retinal structure and had no effect on cone sensitivity or dark adaptation but did slightly accelerate the rate of cone phototransduction termination. These results indicate that Des1 expression in Müller cells is not required for cone visual pigment regeneration in the mouse.—Kiser, P. D., Kolesnikov, A.V., Kiser, J. Z., Dong, Z., Chaurasia, B., Wang, L., Summers, S. A., Hoang, T., Blackshaw, S., Peachey, N. S., Kefalov, V. J., Palczewski, K. Conditional deletion of Des1 in the mouse retina does not impair the visual cycle in cones.
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Affiliation(s)
- Philip D Kiser
- Research Service, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, Ohio, USA.,Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Alexander V Kolesnikov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Jianying Z Kiser
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | | | - Bhagirath Chaurasia
- Department of Nutrition and Integrative Physiology (NUIP), University of Utah, Salt Lake City, Utah, USA.,Diabetes and Metabolism Research Center, University of Utah, Salt Lake City, Utah, USA
| | - Liping Wang
- Department of Nutrition and Integrative Physiology (NUIP), University of Utah, Salt Lake City, Utah, USA.,Diabetes and Metabolism Research Center, University of Utah, Salt Lake City, Utah, USA
| | - Scott A Summers
- Department of Nutrition and Integrative Physiology (NUIP), University of Utah, Salt Lake City, Utah, USA.,Diabetes and Metabolism Research Center, University of Utah, Salt Lake City, Utah, USA
| | - Thanh Hoang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Seth Blackshaw
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Neal S Peachey
- Research Service, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, Ohio, USA.,Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Vladimir J Kefalov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Krzysztof Palczewski
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA.,Department of Ophthalmology, Gavin Herbert Eye Institute, University of California-Irvine, School of Medicine, Irvine, California, USA
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16
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17
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Sarria I, Cao Y, Wang Y, Ingram NT, Orlandi C, Kamasawa N, Kolesnikov AV, Pahlberg J, Kefalov VJ, Sampath AP, Martemyanov KA. LRIT1 Modulates Adaptive Changes in Synaptic Communication of Cone Photoreceptors. Cell Rep 2018; 22:3562-3573. [PMID: 29590623 PMCID: PMC5902029 DOI: 10.1016/j.celrep.2018.03.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 02/10/2018] [Accepted: 02/28/2018] [Indexed: 12/15/2022] Open
Abstract
Cone photoreceptors scale dynamically the sensitivity of responses to maintain responsiveness across wide range of changes in luminance. Synaptic changes contribute to this adaptation, but how this process is coordinated at the molecular level is poorly understood. Here, we report that a cell adhesion-like molecule, LRIT1, is enriched selectively at cone photoreceptor synapses where it engages in a trans-synaptic interaction with mGluR6, the principal receptor in postsynaptic ON-bipolar cells. The levels of LRIT1 are regulated by the neurotransmitter release apparatus that controls photoreceptor output. Knockout of LRIT1 in mice increases the sensitivity of cone synaptic signaling while impairing its ability to adapt to background light without overtly influencing the morphology or molecular composition of photoreceptor synapses. Accordingly, mice lacking LRIT1 show visual deficits under conditions requiring temporally challenging discrimination of visual signals in steady background light. These observations reveal molecular mechanisms involved in scaling synaptic communication in the retina.
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Affiliation(s)
- Ignacio Sarria
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Yan Cao
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Yuchen Wang
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Norianne T Ingram
- Department of Ophthalmology, Stein Eye Institute, UCLA School of Medicine, Los Angeles, CA 90095, USA
| | - Cesare Orlandi
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Naomi Kamasawa
- Electron Microscopy Core Facility, Max Planck Florida Institute, Jupiter, FL 33458, USA
| | - Alexander V Kolesnikov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Johan Pahlberg
- Department of Ophthalmology, Stein Eye Institute, UCLA School of Medicine, Los Angeles, CA 90095, USA
| | - Vladimir J Kefalov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Alapakkam P Sampath
- Department of Ophthalmology, Stein Eye Institute, UCLA School of Medicine, Los Angeles, CA 90095, USA
| | - Kirill A Martemyanov
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA.
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18
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Kiser PD, Zhang J, Sharma A, Angueyra JM, Kolesnikov AV, Badiee M, Tochtrop GP, Kinoshita J, Peachey NS, Li W, Kefalov VJ, Palczewski K. Retinoid isomerase inhibitors impair but do not block mammalian cone photoreceptor function. J Gen Physiol 2018; 150:571-590. [PMID: 29500274 PMCID: PMC5881442 DOI: 10.1085/jgp.201711815] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 12/18/2017] [Accepted: 01/22/2018] [Indexed: 12/11/2022] Open
Abstract
RPE65 is a retinoid isomerase essential for rod function, but its contribution to cone vision is enigmatic. Using selective RPE65 inhibitors, Kiser et al. demonstrate that cone function depends only partially on continuous RPE65 activity, providing support for cone-specific regeneration mechanisms. Visual function in vertebrates critically depends on the continuous regeneration of visual pigments in rod and cone photoreceptors. RPE65 is a well-established retinoid isomerase in the pigment epithelium that regenerates rhodopsin during the rod visual cycle; however, its contribution to the regeneration of cone pigments remains obscure. In this study, we use potent and selective RPE65 inhibitors in rod- and cone-dominant animal models to discern the role of this enzyme in cone-mediated vision. We confirm that retinylamine and emixustat-family compounds selectively inhibit RPE65 over DES1, the putative retinoid isomerase of the intraretinal visual cycle. In vivo and ex vivo electroretinography experiments in Gnat1−/− mice demonstrate that acute administration of RPE65 inhibitors after a bleach suppresses the late, slow phase of cone dark adaptation without affecting the initial rapid portion, which reflects intraretinal visual cycle function. Acute administration of these compounds does not affect the light sensitivity of cone photoreceptors in mice during extended exposure to background light, but does slow all phases of subsequent dark recovery. We also show that cone function is only partially suppressed in cone-dominant ground squirrels and wild-type mice by multiday administration of an RPE65 inhibitor despite profound blockade of RPE65 activity. Complementary experiments in these animal models using the DES1 inhibitor fenretinide show more modest effects on cone recovery. Collectively, these studies demonstrate a role for continuous RPE65 activity in mammalian cone pigment regeneration and provide further evidence for RPE65-independent regeneration mechanisms.
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Affiliation(s)
- Philip D Kiser
- Research Service, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH .,Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH
| | - Jianye Zhang
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH
| | - Aditya Sharma
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO
| | - Juan M Angueyra
- Retinal Neurophysiology Section, National Eye Institute, Bethesda, MD
| | - Alexander V Kolesnikov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO
| | - Mohsen Badiee
- Department of Chemistry, College of Arts and Sciences, Case Western Reserve University, Cleveland, OH
| | - Gregory P Tochtrop
- Department of Chemistry, College of Arts and Sciences, Case Western Reserve University, Cleveland, OH
| | | | - Neal S Peachey
- Research Service, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, OH.,Cole Eye Institute, Cleveland Clinic, Cleveland, OH.,Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH
| | - Wei Li
- Retinal Neurophysiology Section, National Eye Institute, Bethesda, MD
| | - Vladimir J Kefalov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO
| | - Krzysztof Palczewski
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH
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19
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Zeninskaya NA, Kolesnikov AV, Ryabko AK, Shemyakin IG, Dyatlov IA, Kozyr AV. [Aptamers in the Treatment of Bacterial Infections: Problems and Prospects]. ACTA ACUST UNITED AC 2018; 71:350-8. [PMID: 29297663 DOI: 10.15690/vramn591] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Aptamers are short single-stranded oligonucleotides which are selected via targeted chemical evolution in vitro to bind a molecular target of interest. The aptamer selection technology is designated as SELEX (Systematic evolution of ligands by exponential enrichment). SELEX enables isolation of oligonucleotide aptamers binding a wide range of targets of interest with little respect for their nature and molecular weight. A number of applications of aptamer selection were developed ranging from biosensor technologies to antitumor drug discovery. First aptamer-based pharmaceutical (Macugen) was approved by FDA for clinical use in 2004, and since then more than ten aptamer-based drugs undergo various phases of clinical trials. From the medicinal chemist’s point of view, aptamers represent a new class of molecules suitable for the development of new therapeutics. Due to the stability, relative synthesis simplicity, and development of advanced strategies of target specific molecular selection, aptamers attract increased attention of drug discovery community. Difficulties of the development of next-generation antibiotics basing on the conventional basis of combinatorial chemistry and high-throughput screening have also amplified the interest to aptamer-based therapeutic candidates. The present article reviews the investigations focused on the development of antibacterial aptamers and discusses the potential and current limitations of the use of this type of therapeutic molecules.
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20
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Frederiksen R, Nymark S, Kolesnikov AV, Berry JD, Adler L, Koutalos Y, Kefalov VJ, Cornwall MC. Rhodopsin kinase and arrestin binding control the decay of photoactivated rhodopsin and dark adaptation of mouse rods. J Gen Physiol 2017; 148:1-11. [PMID: 27353443 PMCID: PMC4924931 DOI: 10.1085/jgp.201511538] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 06/06/2016] [Indexed: 12/22/2022] Open
Abstract
G-protein receptor kinase and arrestin 1 are required for inactivation of photoactivated vertebrate rhodopsin. Frederiksen et al. show that they additionally regulate the subsequent decay of inactive rhodopsin into opsin and all-trans retinal and therefore dark adaptation. Photoactivation of vertebrate rhodopsin converts it to the physiologically active Meta II (R*) state, which triggers the rod light response. Meta II is rapidly inactivated by the phosphorylation of C-terminal serine and threonine residues by G-protein receptor kinase (Grk1) and subsequent binding of arrestin 1 (Arr1). Meta II exists in equilibrium with the more stable inactive form of rhodopsin, Meta III. Dark adaptation of rods requires the complete thermal decay of Meta II/Meta III into opsin and all-trans retinal and the subsequent regeneration of rhodopsin with 11-cis retinal chromophore. In this study, we examine the regulation of Meta III decay by Grk1 and Arr1 in intact mouse rods and their effect on rod dark adaptation. We measure the rates of Meta III decay in isolated retinas of wild-type (WT), Grk1-deficient (Grk1−/−), Arr1-deficient (Arr1−/−), and Arr1-overexpressing (Arr1ox) mice. We find that in WT mouse rods, Meta III peaks ∼6 min after rhodopsin activation and decays with a time constant (τ) of 17 min. Meta III decay slows in Arr1−/− rods (τ of ∼27 min), whereas it accelerates in Arr1ox rods (τ of ∼8 min) and Grk1−/− rods (τ of ∼13 min). In all cases, regeneration of rhodopsin with exogenous 11-cis retinal is rate limited by the decay of Meta III. Notably, the kinetics of rod dark adaptation in vivo is also modulated by the levels of Arr1 and Grk1. We conclude that, in addition to their well-established roles in Meta II inactivation, Grk1 and Arr1 can modulate the kinetics of Meta III decay and rod dark adaptation in vivo.
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Affiliation(s)
- Rikard Frederiksen
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118
| | - Soile Nymark
- Department of Electronics and Communications Engineering, BioMediTech, Tampere University of Technology, 33720 Tampere, Finland
| | - Alexander V Kolesnikov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110
| | - Justin D Berry
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118
| | - Leopold Adler
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC 29425
| | - Yiannis Koutalos
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC 29425
| | - Vladimir J Kefalov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110
| | - M Carter Cornwall
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118
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21
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Potter C, Zhu W, Razafsky D, Ruzycki P, Kolesnikov AV, Doggett T, Kefalov VJ, Betleja E, Mahjoub MR, Hodzic D. Multiple Isoforms of Nesprin1 Are Integral Components of Ciliary Rootlets. Curr Biol 2017. [PMID: 28625779 DOI: 10.1016/j.cub.2017.05.066] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
SYNE1 (synaptic nuclear envelope 1) encodes multiple isoforms of Nesprin1 (nuclear envelope spectrin 1) that associate with the nuclear envelope (NE) through a C-terminal KASH (Klarsicht/Anc1/Syne homology) domain (Figure 1A) [1-4]. This domain interacts directly with the SUN (Sad1/Unc84) domain of Sun proteins [5-7], a family of transmembrane proteins of the inner nuclear membrane (INM) [8, 9], to form the so-called LINC complexes (linkers of the nucleoskeleton and cytoskeleton) that span the entire NE and mediate nuclear positioning [10-12]. In a stark departure from this classical depiction of Nesprin1 in the context of the NE, we report here that rootletin recruits Nesprin1α at the ciliary rootlets of photoreceptors and identify asymmetric NE aggregates of Nesprin1α and Sun2 that dock filaments of rootletin at the nuclear surface. In NIH 3T3 cells, we show that recombinant rootletin filaments also dock to the NE through the specific recruitment of an ∼600-kDa endogenous isoform of Nesprin1 (Nes1600kDa) and of Sun2. In agreement with the association of Nesprin1α with photoreceptor ciliary rootlets and the functional interaction between rootletin and Nesprin1 in fibroblasts, we demonstrate that multiple isoforms of Nesprin1 are integral components of ciliary rootlets of multiciliated ependymal and tracheal cells. Together, these data provide a novel functional paradigm for Nesprin1 at ciliary rootlets and suggest that the wide spectrum of human pathologies linked to truncating mutations of SYNE1 [13-15] may originate in part from ciliary defects.
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Affiliation(s)
- Chloe Potter
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
| | - Wanqiu Zhu
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
| | - David Razafsky
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
| | - Philip Ruzycki
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
| | - Alexander V Kolesnikov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
| | - Teresa Doggett
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
| | - Vladimir J Kefalov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
| | - Ewelina Betleja
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
| | - Moe R Mahjoub
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
| | - Didier Hodzic
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA.
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Kolesnikov AV, Kozyr AV, Ryabko AK, Shemyakin IG, Dyatlov IA. Immune response to Vi-antigen of Salmonella typhi is dependent on introduction of positive charge and shape of charged group into polysaccharide. DOKL BIOCHEM BIOPHYS 2017; 473:141-144. [PMID: 28510135 DOI: 10.1134/s1607672917020132] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Indexed: 11/23/2022]
Abstract
A model of a controlled conversion of polysaccharide Vi-antigen of S. typhi into zwitterionic antigen is proposed. The immunological properties of modifications of this antigen conjugated to a protein support were studied.
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Affiliation(s)
- A V Kolesnikov
- State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow oblast, 142279, Russia
| | - A V Kozyr
- State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow oblast, 142279, Russia.
| | - A K Ryabko
- State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow oblast, 142279, Russia
| | - I G Shemyakin
- State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow oblast, 142279, Russia
| | - I A Dyatlov
- State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow oblast, 142279, Russia
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23
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Kolesnikov AV, Kozyr AV, Ryabko AK, Shemyakin IG. Ultrasensitive detection of protease activity of anthrax and botulinum toxins by a new PCR-based assay. Pathog Dis 2015; 74:ftv112. [PMID: 26620058 DOI: 10.1093/femspd/ftv112] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/24/2015] [Indexed: 11/14/2022] Open
Abstract
Anthrax and botulism are dangerous infectious diseases that can be fatal unless detected and treated quickly. Fatalities from these diseases are primarily due to endopeptidase toxins secreted by the pathogens. Rapid and sensitive detection of the presence of active toxins is the key element for protection from natural outbreaks of anthrax and botulism, as well as from the threat of bioterrorism. We describe an ultrasensitive polymerase chain reaction (PCR)-based assay for detecting proteolytic activity of anthrax and botulinum toxins using composite probes consisting of covalent peptide-DNA conjugate for the detection of anthrax, and noncovalent protein-aptamer assembly to assay botulinum toxin activity. Probes immobilized on the solid-phase support are cleaved by toxins to release DNA, which is detected by real-time PCR. Both assays can detect subpicogram quantities of active toxins isolated from composite matrices. Special procedures were developed to isolate intact toxins from the matrices under mild conditions. The assay is rapid, uses proven technologies, and can be modified to detect other proteolytic and biopolymer-degrading enzymes.
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Affiliation(s)
- Alexander V Kolesnikov
- State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow Region 142279, Russia Institute of Immunological Engineering, Lyubuchany, Moscow Region 142380, Russia
| | - Arina V Kozyr
- State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow Region 142279, Russia
| | - Alyona K Ryabko
- State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow Region 142279, Russia
| | - Igor G Shemyakin
- State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow Region 142279, Russia
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Kolesnikov AV, Maeda A, Tang PH, Imanishi Y, Palczewski K, Kefalov VJ. Retinol dehydrogenase 8 and ATP-binding cassette transporter 4 modulate dark adaptation of M-cones in mammalian retina. J Physiol 2015; 593:4923-41. [PMID: 26350353 DOI: 10.1113/jp271285] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 09/02/2015] [Indexed: 12/13/2022] Open
Abstract
KEY POINTS This study explores the molecular mechanisms that regulate the recycling of chromophore required for pigment regeneration in mammalian cones. We report that two chromophore binding proteins, retinol dehydrogenase 8 (RDH8) and photoreceptor-specific ATP-binding cassette transporter (ABCA4) accelerate the dark adaptation of cones, first, directly, by facilitating the processing of chromophore in cones, and second, indirectly, by accelerating the turnover of chromophore in rods, which is then recycled and delivered to both rods and cones. Preventing competition with the rods by knocking out rhodopsin accelerated cone dark adaptation, demonstrating the interplay between rod and cone pigment regeneration driven by the retinal pigment epithelium (RPE). This novel interdependence of rod and cone pigment regeneration should be considered when developing therapies targeting the recycling of chromophore for rods, and evaluating residual cone function should be a critical test for such regimens targeting the RPE. ABSTRACT Rapid recycling of visual chromophore and regeneration of the visual pigment are critical for the continuous function of mammalian cone photoreceptors in daylight vision. However, the molecular mechanisms modulating the supply of visual chromophore to cones have remained unclear. Here we explored the roles of two chromophore-binding proteins, retinol dehydrogenase 8 (RDH8) and photoreceptor-specific ATP-binding cassette transporter 4 (ABCA4), in dark adaptation of mammalian cones. We report that young adult RDH8/ABCA4-deficient mice have normal M-cone morphology but reduced visual acuity and photoresponse amplitudes. Notably, the deletion of RDH8 and ABCA4 suppressed the dark adaptation of M-cones driven by both the intraretinal visual cycle and the retinal pigmented epithelium (RPE) visual cycle. This delay can be caused by two separate mechanisms: direct involvement of RDH8 and ABCA4 in cone chromophore processing, and an indirect effect from the delayed recycling of chromophore by the RPE due to its slow release from RDH8/ABCA4-deficient rods. Intriguingly, our data suggest that RDH8 could also contribute to the oxidation of cis-retinoids in cones, a key reaction of the retina visual cycle. Finally, we dissected the roles of rod photoreceptors and RPE for dark adaptation of M-cones. We found that rods suppress, whereas RPE promotes, cone dark adaptation. Thus, therapeutic approaches targeting the RPE visual cycle could have adverse effects on the function of cones, making the evaluation of residual cone function a critical test for regimens targeting the RPE.
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Affiliation(s)
- Alexander V Kolesnikov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO, 63110, USA
| | - Akiko Maeda
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH, 44106, USA.,Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Peter H Tang
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, 29425, USA.,Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Yoshikazu Imanishi
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Krzysztof Palczewski
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Vladimir J Kefalov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Saint Louis, MO, 63110, USA
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Kolesnikov AV, Kozyr AV, Schemyakin IG, Dyatlov IA. [CONTEMPORARY CONCEPTION OF IMMUNE RESPONSE ACTIVATION MECHA- NISM BY CONJUGATED POLYSACCHARIDE VACCINES]. Zh Mikrobiol Epidemiol Immunobiol 2015:97-106. [PMID: 26259279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Vaccination remains the most effective method of control of spread of a whole range of infections of both viral and bacterial nature. Many bacterial pathogens (Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae) carry polysaccharide capsule on the surface, that is one of the elements of protection from host organism immune system. At the same time, vaccination with bacteria exopolysaccharides (EPS) ensures infection neutralization. Effectiveness of such vaccine prophylaxis is limited by age of the vaccinated, intensity and duration of the immunity, development of secondary immune response. EPS conjugation with protein antigens was known for a long time to ensure activation of T-cell immunity against EPS and formation of secondary immune response. However, detailed studies of mechanism of immunity modulation by a protein partner as part of a glycoconjugate has not been carried out. T-lymphocyte activation was traditionally thought to occur exclusively due to peptide presentation, that are products of processing of protein component of the conjugate. Recently, information, accumulated in the field of natural carbohydrate, glycolipid and glycoprotein antigen presentation to T-cells, has generated interest in studying mechanisms of cell immunity activation by conjugated vaccines. Progress in this field, as well as development of novel chemical and biochemical, including combinative technologies of synthesis and study of these molecules, opens new opportunities for detailed understanding of mechanism of action for conjugated vaccines and creation of glycoconjugates with increased effectiveness of protective action.
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26
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Sarria I, Pahlberg J, Cao Y, Kolesnikov AV, Kefalov VJ, Sampath AP, Martemyanov KA. Sensitivity and kinetics of signal transmission at the first visual synapse differentially impact visually-guided behavior. eLife 2015; 4:e06358. [PMID: 25879270 PMCID: PMC4412108 DOI: 10.7554/elife.06358] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 04/11/2015] [Indexed: 12/29/2022] Open
Abstract
In the retina, synaptic transmission between photoreceptors and downstream ON-bipolar neurons (ON-BCs) is mediated by a GPCR pathway, which plays an essential role in vision. However, the mechanisms that control signal transmission at this synapse and its relevance to behavior remain poorly understood. In this study we used a genetic system to titrate the rate of GPCR signaling in ON-BC dendrites by varying the concentration of key RGS proteins and measuring the impact on transmission of signal between photoreceptors and ON-BC neurons using electroretinography and single cell recordings. We found that sensitivity, onset timing, and the maximal amplitude of light-evoked responses in rod- and cone-driven ON-BCs are determined by different RGS concentrations. We further show that changes in RGS concentration differentially impact visually guided-behavior mediated by rod and cone ON pathways. These findings illustrate that neuronal circuit properties can be modulated by adjusting parameters of GPCR-based neurotransmission at individual synapses. DOI:http://dx.doi.org/10.7554/eLife.06358.001 At the back of the eye, a structure called the retina contains several types of cell that convert light into the electrical signals that the brain interprets to produce vision. Cells called rods and cones detect the light, and then signal to other neurons in the retina that relay this information to the brain. Rods and cones are specialized to respond best to different visual features: cones detect color and can track rapid movement; whereas rods are more sensitive to low light levels and so enable night vision. All rods and cones communicate with particular types of neuron called an ‘ON bipolar cell’: rods send their information to rod-specific ON bipolar cells and cones to cone ON-bipolar cells. To maintain the differences in how visual features are detected, the signals sent by the rod or cone cells need to be tuned separately. Previous studies showed that bipolar cells rely on the action of proteins called RGSs to control how information is passed from rods and cones to ON bipolar cells. However, how the RGS proteins produce their effects is not well understood, and neither is their impact on vision or behavior. Sarria et al. used a genetic approach to create mice that progressively lost RGS proteins from their retina over the course of several weeks. Recording the nerve impulses produced by the bipolar cells as light shone on the retina revealed that RGS depletion affects these neurons in three ways: how sensitive they are to the signals sent by the rod and cone cells, how quickly they respond to a signal, and the size of the electrical response that they produce. Sarria et al. then investigated how these changes affected the behavior of the mice. To test the response of the rod cells, the mice performed tasks in dim light. This revealed that it was only when the sensitivity of the bipolar cells decreased that the mice performed worse. However, in a task involving fast-moving objects that investigated the response of cone cells, only changes to the speed of the response affected vision. Therefore, the RGS protein has different effects on the signals from rod cells and cone cells. These findings will be useful for understanding how different light sensitive cells in the retina communicate their signals to extract important visual features, allowing us to both see well at night and track rapid changes in scenery on a bright sunny day. DOI:http://dx.doi.org/10.7554/eLife.06358.002
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Affiliation(s)
- Ignacio Sarria
- Department of Neuroscience, The Scripps Research Institute, Jupiter, United States
| | - Johan Pahlberg
- Jules Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles, Los Angeles, United States
| | - Yan Cao
- Department of Neuroscience, The Scripps Research Institute, Jupiter, United States
| | - Alexander V Kolesnikov
- Department of Ophthalmology and Visual Sciences, Washington University in St.Louis, St. Louis, United States
| | - Vladimir J Kefalov
- Department of Ophthalmology and Visual Sciences, Washington University in St.Louis, St. Louis, United States
| | - Alapakkam P Sampath
- Jules Stein Eye Institute, Department of Ophthalmology, University of California, Los Angeles, Los Angeles, United States
| | - Kirill A Martemyanov
- Department of Neuroscience, The Scripps Research Institute, Jupiter, United States
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27
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Zhang N, Tsybovsky Y, Kolesnikov AV, Rozanowska M, Swider M, Schwartz SB, Stone EM, Palczewska G, Maeda A, Kefalov VJ, Jacobson SG, Cideciyan AV, Palczewski K. Protein misfolding and the pathogenesis of ABCA4-associated retinal degenerations. Hum Mol Genet 2015; 24:3220-37. [PMID: 25712131 DOI: 10.1093/hmg/ddv073] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 02/22/2015] [Indexed: 12/13/2022] Open
Abstract
Mutations in the ABCA4 gene are a common cause of autosomal recessive retinal degeneration. All mouse models to date are based on knockouts of Abca4, even though the disease is often caused by missense mutations such as the complex allele L541P;A1038V (PV). We now show that the PV mutation causes severe human disease whereas the V mutation alone causes mild disease. Mutant ABCA4 proteins expressed heterologously in mammalian cells retained normal cellular localization. However, basal and all-trans-retinal-stimulated ATPase activities were reduced substantially for P and PV but only mildly for V. Electron microscopy revealed marked structural changes and misfolding for the P and PV mutants but few changes for the V mutant, consistent with the disease severity difference in patients. We generated Abca4(PV/PV) knock-in mice homozygous for the complex PV allele to investigate the effects of this misfolding mutation in vivo. Mutant ABCA4 RNA levels approximated WT ABCA4 RNA levels but, surprisingly, only trace amounts of mutant ABCA4 protein were noted in the retina. RNA sequencing of WT, Abca4(-/-) and Abca4(PV/PV) mice revealed mild gene expression alterations in the retina and RPE. Similar to Abca4(-/-) mice, Abca4(PV/PV) mice showed substantial A2E and lipofuscin accumulation in their RPE cells but no retinal degeneration up to 12 months of age. Thus, rapid degradation of this large misfolded mutant protein in mouse retina caused little detectable photoreceptor degeneration. These findings suggest likely differences in the unfolded protein response between murine and human photoreceptors and support development of therapies directed at increasing this capability in patients.
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Affiliation(s)
- Ning Zhang
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology and
| | - Yaroslav Tsybovsky
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology and
| | - Alexander V Kolesnikov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid Avenue, Campus Box 8096, Saint Louis, MO 63110, USA
| | - Malgorzata Rozanowska
- Department of Ophthalmology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Malgorzata Swider
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Sharon B Schwartz
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Edwin M Stone
- Department of Ophthalmology, University of Iowa Carver College of Medicine, Iowa City, IA, USA Howard Hughes Medical Institute, Iowa City, IA, USA and
| | | | - Akiko Maeda
- Department of Ophthalmology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Vladimir J Kefalov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid Avenue, Campus Box 8096, Saint Louis, MO 63110, USA
| | - Samuel G Jacobson
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Artur V Cideciyan
- Department of Ophthalmology, Scheie Eye Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Krzysztof Palczewski
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology and
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Kolesnikov AV, Ryabko AK, Shemyakin IG, Kozyr AV. [Development of Specific Therapy to Category A Toxic Infections]. Vestn Ross Akad Med Nauk 2015:428-434. [PMID: 26710525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Category A select agents continue to be major threat to human population both as naturally occurring diseases and as potential weapon of bioterrorists. Anthrax and botulism are probably the most threatening agents as both have virtually uncontrolled natural reservoirs from which they can be isolated and propagated. Available specific antitoxin therapy of both diseases is outdated; its efficiency is questionable as well as safety of reactogenic or human-derived components used in treatment. Highly sensitive toxin detection techniques are still not as widespread as it needed for timely alerting medical services. There is urgent need of pre-exposure prophylaxis and postexposure specific antitoxin therapy for anthrax and botulism. Analysis of modern studies in the field suggests oligoclonal antibodies acting against receptor-binding toxin subunits and nucleic acid aptamers as allosteric inhibitors of metlloproteolytic toxin components as the most promising candidates for development of efficient antitoxin therapy.
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29
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Cain MD, Vo BQ, Kolesnikov AV, Kefalov VJ, Culican SM, Kerschensteiner D, Blumer KJ. An allosteric regulator of R7-RGS proteins influences light-evoked activity and glutamatergic waves in the inner retina. PLoS One 2013; 8:e82276. [PMID: 24349243 PMCID: PMC3857278 DOI: 10.1371/journal.pone.0082276] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 10/31/2013] [Indexed: 11/23/2022] Open
Abstract
In the outer retina, G protein-coupled receptor (GPCR) signaling mediates phototransduction and synaptic transmission between photoreceptors and ON bipolar cells. In contrast, the functions of modulatory GPCR signaling networks in the inner retina are less well understood. We addressed this question by determining the consequences of augmenting modulatory Gi/o signaling driven by endogenous transmitters. This was done by analyzing the effects of genetically ablating the R7 RGS-binding protein (R7BP), a membrane-targeting protein and positive allosteric modulator of R7-RGS (regulator of the G protein signaling 7) family that deactivates Gi/oα subunits. We found that R7BP is expressed highly in starburst amacrine cells and retinal ganglion cells (RGCs). As indicated by electroretinography and multielectrode array recordings of adult retina, ablation of R7BP preserved outer retina function, but altered the firing rate and latency of ON RGCs driven by rods and cones but not rods alone. In developing retina, R7BP ablation increased the burst duration of glutamatergic waves whereas cholinergic waves were unaffected. This effect on glutamatergic waves did not result in impaired segregation of RGC projections to eye-specific domains of the dorsal lateral geniculate nucleus. R7BP knockout mice exhibited normal spatial contrast sensitivity and visual acuity as assessed by optomotor reflexes. Taken together these findings indicate that R7BP-dependent regulation of R7-RGS proteins shapes specific aspects of light-evoked and spontaneous activity of RGCs in mature and developing retina.
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Affiliation(s)
- Matthew D. Cain
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Bradly Q. Vo
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Alexander V. Kolesnikov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Vladimir J. Kefalov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Susan M. Culican
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Daniel Kerschensteiner
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Kendall J. Blumer
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail:
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30
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Sakami S, Kolesnikov AV, Kefalov VJ, Palczewski K. P23H opsin knock-in mice reveal a novel step in retinal rod disc morphogenesis. Hum Mol Genet 2013; 23:1723-41. [PMID: 24214395 DOI: 10.1093/hmg/ddt561] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Retinal rod photoreceptor cells have double membrane discs located in their outer segments (ROS) that are continuously formed proximally from connecting cilia (CC) and phagocytized distally by the retinal pigmented epithelium. The major component of these rod discs, the light-sensitive visual pigment rhodopsin (Rho), consists of an opsin protein linked to 11-cis-retinal. The P23H mutation of rod opsin (P23H opsin) is the most common cause of human blinding autosomal dominant retinitis pigmentosa (adRP). A mouse model of adRP with this mutation (Rho(P23H/+)) shows low levels of P23H opsin protein, partial misalignment of discs and progressive retinal degeneration. However, the impact of mutant P23H opsin on the formation of abnormal discs is unclear and it is still unknown whether this mutant pigment can mediate phototransduction. Using transretinal ERG recordings, we demonstrate that P23H mutant Rho can trigger phototransduction but Rho(P23H/P23H) rods are ∼17 000-fold less sensitive to light than Rho(+/+) rods and produce abnormally fast photo-responses. By analyzing homozygous Rho(P23H/P23H) knock-in mice, we show that P23H opsin is transported to ciliary protrusions where it forms sagittally elongated discs. Transmission electron microscopy of postnatal day (PND) 14 Rho(P23H/+) mouse retina revealed disordered sagittally oriented discs before the onset of retinal degeneration. Surprisingly, we also observed smaller, immature sagittally oriented discs in PND14 Rho(+/)(-) and Rho(+/+) mice that were not seen in older animals. These findings provide fundamental insights into the pathogenesis of the P23H mutant opsin and reveal a novel early sagittally aligned disc formation step in normal ROS disc expansion.
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Affiliation(s)
- Sanae Sakami
- Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
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Kim JY, Zhao H, Martinez J, Doggett TA, Kolesnikov AV, Tang PH, Ablonczy Z, Chan CC, Zhou Z, Green DR, Ferguson TA. Noncanonical autophagy promotes the visual cycle. Cell 2013; 154:365-76. [PMID: 23870125 DOI: 10.1016/j.cell.2013.06.012] [Citation(s) in RCA: 257] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 05/06/2013] [Accepted: 06/06/2013] [Indexed: 01/08/2023]
Abstract
Phagocytosis and degradation of photoreceptor outer segments (POS) by retinal pigment epithelium (RPE) is fundamental to vision. Autophagy is also responsible for bulk degradation of cellular components, but its role in POS degradation is not well understood. We report that the morning burst of RPE phagocytosis coincided with the enzymatic conversion of autophagy protein LC3 to its lipidated form. LC3 associated with single-membrane phagosomes containing engulfed POS in an Atg5-dependent manner that required Beclin1, but not the autophagy preinitiation complex. The importance of this process was verified in mice with Atg5-deficient RPE cells that showed evidence of disrupted lysosomal processing. These mice also exhibited decreased photoreceptor responses to light stimuli and decreased chromophore levels that were restored with exogenous retinoid supplementation. These results establish that the interplay of phagocytosis and autophagy within the RPE is required for both POS degradation and the maintenance of retinoid levels to support vision.
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Affiliation(s)
- Ji-Young Kim
- Department of Ophthalmology and Visual Sciences, Washington University, St. Louis School of Medicine, St. Louis, MO 63110, USA
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Kozyr' AV, Luneva NM, Khlyntseva AE, Shemiakin IG, Krasavtseva ON, Kolesnikov AV. [Antibiotic-dependent selection of the E. coli clones with increased chaperone activity for highly-efficient production of the full-length soluble New Delhi metallo-beta-lactamase]. Mol Gen Mikrobiol Virusol 2013:15-22. [PMID: 24645273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The spread of the New Delhi metallo-beta-lactamase (NDM-1), a plasmid-borne enzyme conferring bacterial resistance to any known beta-lactam antibiotics, represents the global health threat. There is an urgent need to develop the efficient NDM-1 inhibitors of various mode of action thereby necessitating structural studies of the enzyme as well as analysis of the secretion pathway and localization of the protein. The recombinant full-length NDM-1 is produced in E. coli in the inactive form and is mostly accumulated in the inclusion bodies. The secreted recombinant NDM-1 forms are several N-terminally truncated species. The robust expression system capable of high-level production of the full-length NDM-1 and derivatives thereof is required to obtain NDM-1 in the quantities necessary for drug discovery, diagnostics, and research purposes. Therefore, we developed a new system that utilizes antibiotic pressure to select E. coli producing increased quantity of soluble NDM-1 and showed that an increase in the NDM-1 solubility occurs in the bacterial clones producing increased amounts in the chaperones.
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Zhang N, Kolesnikov AV, Jastrzebska B, Mustafi D, Sawada O, Maeda T, Genoud C, Engel A, Kefalov VJ, Palczewski K. Autosomal recessive retinitis pigmentosa E150K opsin mice exhibit photoreceptor disorganization. J Clin Invest 2012; 123:121-37. [PMID: 23221340 DOI: 10.1172/jci66176] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 10/04/2012] [Indexed: 12/13/2022] Open
Abstract
The pathophysiology of the E150K mutation in the rod opsin gene associated with autosomal recessive retinitis pigmentosa (arRP) has yet to be determined. We generated knock-in mice carrying a single nucleotide change in exon 2 of the rod opsin gene resulting in the E150K mutation. This novel mouse model displayed severe retinal degeneration affecting rhodopsin's stabilization of rod outer segments (ROS). Homozygous E150K (KK) mice exhibited early-onset retinal degeneration, with disorganized ROS structures, autofluorescent deposits in the subretinal space, and aberrant photoreceptor phagocytosis. Heterozygous (EK) mice displayed a delayed-onset milder retinal degeneration. Further, mutant receptors were mislocalized to the inner segments and perinuclear region. Though KK mouse rods displayed markedly decreased phototransduction, biochemical studies of the mutant rhodopsin revealed only minimally affected chromophore binding and G protein activation. Ablation of the chromophore by crossing KK mice with mice lacking the critical visual cycle protein LRAT slowed retinal degeneration, whereas blocking phototransduction by crossing KK mice with GNAT1-deficient mice slightly accelerated this process. This study highlights the importance of proper higher-order organization of rhodopsin in the native tissue and provides information about the signaling properties of this mutant rhodopsin. Additionally, these results suggest that patients heterozygous for the E150K mutation should be periodically reevaluated for delayed-onset retinal degeneration.
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Affiliation(s)
- Ning Zhang
- Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44160, USA
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Abstract
There are two distinct classes of image-forming photoreceptors in the vertebrate retina: rods and cones. Rods are able to detect single photons of light whereas cones operate continuously under rapidly changing bright light conditions. Absorption of light by rod- and cone-specific visual pigments in the outer segments of photoreceptors triggers a phototransduction cascade that eventually leads to closure of cyclic nucleotide-gated channels on the plasma membrane and cell hyperpolarization. This light-induced change in membrane current and potential can be registered as a photoresponse, by either classical suction electrode recording technique or by transretinal electroretinogram recordings (ERG) from isolated retinas with pharmacologically blocked postsynaptic response components. The latter method allows drug-accessible long-lasting recordings from mouse photoreceptors and is particularly useful for obtaining stable photoresponses from the scarce and fragile mouse cones. In the case of cones, such experiments can be performed both in dark-adapted conditions and following intense illumination that bleaches essentially all visual pigment, to monitor the process of cone photosensitivity recovery during dark adaptation. In this video, we will show how to perform rod- and M/L-cone-driven transretinal recordings from dark-adapted mouse retina. Rod recordings will be carried out using retina of wild type (C57Bl/6) mice. For simplicity, cone recordings will be obtained from genetically modified rod transducin α-subunit knockout (Tα(-/-)) mice which lack rod signaling(8).
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Affiliation(s)
- Alexander V Kolesnikov
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, Washington, USA.
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Lomonosova E, Kolesnikov AV, Kefalov VJ, Kisselev OG. Signaling states of rhodopsin in rod disk membranes lacking transducin βγ-complex. Invest Ophthalmol Vis Sci 2012; 53:1225-33. [PMID: 22266510 DOI: 10.1167/iovs.11-9350] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To characterize the possible role of transducin Gtβγ-complex in modulating the signaling properties of photoactivated rhodopsin and its lifetime in rod disc membranes and intact rods. METHODS Rhodopsin photolysis was studied using UV-visible spectroscopy and rapid scanning spectroscopy in the presence of hydroxylamine in highly purified wild-type and Gtγ-deficient mouse rod disc membranes. Complex formation between photoactivated rhodopsin and transducin was measured by extra-metarhodopsin (meta) II assay. Recovery of dark current and flash sensitivity in individual intact wild-type and Gtγ-deficient mouse rods was measured by single-cell suction recordings. RESULTS Photoconversion of rhodopsin to meta I/meta II equilibrium proceeds normally after elimination of the Gtβγ-complex. The meta I/meta II ratio, the rate of meta II decay, the reactivity of meta II toward hydroxylamine, and the rate of meta III formation in Gtγ-deficient rod disc membranes were identical with those observed in wild-type samples. Under low-intensity illumination, the amount of extra-meta II in Gtγ-deficient discs was significantly reduced. The initial rate of dark current recovery after 12% rhodopsin bleach was three times faster in Gtγ-deficient rods, whereas the rate of the late current recovery was largely unchanged. Mutant rods also exhibited faster postbleach recovery of flash sensitivity. CONCLUSIONS Photoactivation and thermal decay of rhodopsin proceed similarly in wild-type and Gtγ-deficient mouse rods, but the complex formation between photoactivated rhodopsin and transducin is severely compromised in the absence of Gtβγ. The resultant lower transduction activation contributes to faster photoresponse recovery after a moderate pigment bleach in Gtγ-deficient rods.
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Affiliation(s)
- Elena Lomonosova
- Department of Ophthalmology, Saint Louis University School of Medicine, Saint Louis, MO, USA
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Kolesnikov AV, Kozyr' AV, Shemiakin IG. [Prospects for application of aptamers in diagnostics of bacterial infections]. Mol Gen Mikrobiol Virusol 2012:3-8. [PMID: 22937563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Nucleic acid-based aptamers are widely accepted as promising tools for development of a plethora of diagnostic and therapeutic preparations, as well as means ofenvironmental monitoring. Aptamers can be regarded as fully synthetic analogs of antibodies. At the same time, certain properties ofaptamers render them superior to antibodies in terms of development of new diagnostic and monitoring systems that combine high sensitivity and specificity with high reproducibility and inexpensive manufacturing. In particular, the aptamers tailored to bind biomolecules and live cells can be employed in solving the problem of combining short analysis time with high sensitivity and specificity in detection of pathogenic bacteria. The present review summarizes the current state of the techniques developed for aptamer-based detection of bacteria and their components and discusses the potential of their practical application.
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Kuznetsov NA, Kozyr AV, Dronina MA, Smirnov IV, Kaliberda EN, Mikhailova AG, Rumsh LD, Fedorova OS, Gabibov AG, Kolesnikov AV. Pre-steady-state kinetics of interaction of wild-type and multiple drug-resistant HIV protease with first and second generation inhibitory drugs. DOKL BIOCHEM BIOPHYS 2011; 440:239-43. [PMID: 22095129 DOI: 10.1134/s1607672911050139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Indexed: 11/22/2022]
Affiliation(s)
- N A Kuznetsov
- Institute of Chemical Biology and Fundamental Medicine, Russian Academy of Sciences, Novosibirsk, Russia
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Estevez ME, Kolesnikov AV, Ala-Laurila P, Crouch RK, Govardovskii VI, Cornwall MC. The 9-methyl group of retinal is essential for rapid Meta II decay and phototransduction quenching in red cones. J Gen Physiol 2009; 134:137-50. [PMID: 19635855 PMCID: PMC2717693 DOI: 10.1085/jgp.200910232] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Accepted: 07/13/2009] [Indexed: 11/21/2022] Open
Abstract
Cone photoreceptors of the vertebrate retina terminate their response to light much faster than rod photoreceptors. However, the molecular mechanisms underlying this rapid response termination in cones are poorly understood. The experiments presented here tested two related hypotheses: first, that the rapid decay rate of metarhodopsin (Meta) II in red-sensitive cones depends on interactions between the 9-methyl group of retinal and the opsin part of the pigment molecule, and second, that rapid Meta II decay is critical for rapid recovery from saturation of red-sensitive cones after exposure to bright light. Microspectrophotometric measurements of pigment photolysis, microfluorometric measurements of retinol production, and single-cell electrophysiological recordings of flash responses of salamander cones were performed to test these hypotheses. In all cases, cones were bleached and their visual pigment was regenerated with either 11-cis retinal or with 11-cis 9-demethyl retinal, an analogue of retinal lacking the 9-methyl group. Meta II decay was four to five times slower and subsequent retinol production was three to four times slower in red-sensitive cones lacking the 9-methyl group of retinal. This was accompanied by a significant slowing of the recovery from saturation in cones lacking the 9-methyl group after exposure to bright (>0.1% visual pigment photoactivated) but not dim light. A mathematical model of the turn-off process of phototransduction revealed that the slower recovery of photoresponse can be explained by slower Meta decay of 9-demethyl visual pigment. These results demonstrate that the 9-methyl group of retinal is required for steric chromophore-opsin interactions that favor both the rapid decay of Meta II and the rapid response recovery after exposure to bright light in red-sensitive cones.
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Affiliation(s)
- Maureen E Estevez
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118, USA.
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Zakharova MY, Kuznetsov NA, Dubiley SA, Kozyr AV, Fedorova OS, Chudakov DM, Knorre DG, Shemyakin IG, Gabibov AG, Kolesnikov AV. Substrate recognition of anthrax lethal factor examined by combinatorial and pre-steady-state kinetic approaches. J Biol Chem 2009; 284:17902-13. [PMID: 19359249 DOI: 10.1074/jbc.m807510200] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lethal factor (LF), a zinc-dependent protease of high specificity produced by Bacillus anthracis, is the effector component of the binary toxin that causes death in anthrax. New therapeutics targeting the toxin are required to reduce systemic anthrax-related fatalities. In particular, new insights into the LF catalytic mechanism will be useful for the development of LF inhibitors. We evaluated the minimal length required for formation of bona fide LF substrates using substrate phage display. Phage-based selection yielded a substrate that is cleaved seven times more efficiently by LF than the peptide targeted in the protein kinase MKK6. Site-directed mutagenesis within the metal-binding site in the LF active center and within phage-selected substrates revealed a complex pattern of LF-substrate interactions. The elementary steps of LF-mediated proteolysis were resolved by the stopped-flow technique. Pre-steady-state kinetics of LF proteolysis followed a four-step mechanism as follows: initial substrate binding, rearrangement of the enzyme-substrate complex, a rate-limiting cleavage step, and product release. Examination of LF interactions with metal ions revealed an unexpected activation of the protease by Ca(2+) and Mn(2+). Based on the available structural and kinetic data, we propose a model for LF-substrate interaction. Resolution of the kinetic and structural parameters governing LF activity may be exploited to design new LF inhibitors.
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Affiliation(s)
- Maria Yu Zakharova
- M. M. Shemyakin & Yu. A. Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997
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Belova EV, Kolesnikov AV, Zakharova MI, Dubileĭ SA, Diatlov IA, Shemiakin IG. [Characteristics of the immune response to the lethal toxin of Bacillus anthracis]. Bioorg Khim 2008; 34:639-44. [PMID: 19060938 DOI: 10.1134/s1068162008050063] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We and other authors have recently shown that the pattern of the immune response to components of anthrax, the Bacillus anthracis lethal toxin, is complex. In addition to neutralizing antibodies, the antitoxin antibody pool contains antibodies enhancing the toxin lethal action. We mapped the epitopes in the protective antigen that are responsible for the induction of both antibody types. In this study, we obtained new data on the cytotoxicity of the B. anthracis lethal toxin toward the J774 A.1 cell line in the presence of monoclonal antibodies to various domains of the protective antigen and the lethal factor. The role of the Fc fragment of immunoglobulins in enhancing the lethal toxin action was shown. These results may serve as a basis for the development of a new generation vaccine for anthrax.
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Ponomarenko NA, Pillet D, Paon M, Vorobiev II, Smirnov IV, Adenier H, Avalle B, Kolesnikov AV, Kozyr AV, Thomas D, Gabibov AG, Friboulet A. Anti-idiotypic antibody mimics proteolytic function of parent antigen. Biochemistry 2007; 46:14598-609. [PMID: 18020454 DOI: 10.1021/bi7013954] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Functional imaging of subtilisin Carlsberg active center by the idiotypic network yielded a catalytic anti-idiotypic antibody with endopeptidase, amidase, and esterase activities. A monoclonal antibody inhibitory to subtilisin (Ab1 5-H4) was employed as the template for guiding the idiotypic network to produce the catalytic anti-idiotypic Ab2 6B8-E12. Proteolytic activity of 6B8-E12 was demonstrated by zymography using self-quenched fluorescein-BSA conjugate and in a coupled assay detecting Ab2-dependent RNase A inactivation. Cleavage of peptide substrates by 6B8-E12 revealed distinct patterns of hydrolysis with high preference for aromatic residues before or after the scissile bond. Catalytic activity of Ab2 was inhibited by phenylmethylsulfonyl fluoride, a mechanism-based inhibitor of serine hydrolases. 5-H4 and 6B8-E12 were cloned, produced in Escherichia coli as single-chain variable fragments (scFvs), and purified. Kinetic parameters for amidolytic and esterolytic activities were similar in Ab2 and its scFv derivative. Although the antigen-specific portion of 6B8-E12 possesses no primary structure similarity to subtilisin, it mimics proteolytic and amidolytic functions of the parental antigen, albeit with 4 orders of magnitude slower acceleration rates. The lack of detectable endopeptidase activity of 6B8-E12 scFv raises interesting issues concerning general evolution of catalytic activity. The in silico 3D models of Ab1 and Ab2 revealed strong structural similarity to known anti-protease antibodies and to abzymes, respectively. These results indicate that the idiotypic network is capable, to a significant extent, of reproducing catalytic apparatus of serine proteases and further validate the use of imaging of enzyme active centers by the immune system for induction of abzymes accelerating energy-demanding amide bond hydrolysis.
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Affiliation(s)
- Natalia A Ponomarenko
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry RAS, 16/10, Miklukho-Maklaya str, Moscow, 117997, Russia
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Stoliar VP, Zubkov AD, Kolesnikov AV. [About the medical information individual carrier for the Air Forces flying staff]. Voen Med Zh 2007; 328:11-6. [PMID: 17580483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
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Kolesnikov AV, Ala-Laurila P, Shukolyukov SA, Crouch RK, Wiggert B, Estevez ME, Govardovskii VI, Cornwall MC. Visual cycle and its metabolic support in gecko photoreceptors. Vision Res 2006; 47:363-74. [PMID: 17049961 DOI: 10.1016/j.visres.2006.08.024] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2006] [Revised: 08/15/2006] [Accepted: 08/16/2006] [Indexed: 11/30/2022]
Abstract
Photoreceptors of nocturnal geckos are transmuted cones that acquired rod morphological and physiological properties but retained cone-type phototransduction proteins. We have used microspectrophotometry and microfluorometry of solitary isolated green-sensitive photoreceptors of Tokay gecko to study the initial stages of the visual cycle within these cells. These stages are the photolysis of the visual pigment, the reduction of all-trans retinal to all-trans retinol, and the clearance of all-trans retinol from the outer segment (OS) into the interphotoreceptor space. We show that the rates of decay of metaproducts (all-trans retinal release) and retinal-to-retinol reduction are intermediate between those of typical rods and cones. Clearance of retinol from the OS proceeds at a rate that is typical of rods and is greatly accelerated by exposure to interphotoreceptor retinoid-binding protein, IRBP. The rate of retinal release from metaproducts is independent of the position within the OS, while its conversion to retinol is strongly spatially non-uniform, being the fastest at the OS base and slowest at the tip. This spatial gradient of retinol production is abolished by dialysis of saponin-permeabilized OSs with exogenous NADPH or substrates for its production by the hexose monophosphate pathway (NADP+glucose-6-phosphate or 6-phosphogluconate, glucose-6-phosphate alone). Following dialysis by these agents, retinol production is accelerated by several-fold compared to the fastest rates observed in intact cells in standard Ringer solution. We propose that the speed of retinol production is set by the availability of NADPH which in turn depends on ATP supply within the outer segment. We also suggest that principal source of this ATP is from mitochondria located within the ellipsoid region of the inner segment.
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Affiliation(s)
- A V Kolesnikov
- Institute for Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia
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Bagaudinov KG, Zubkov AD, Kolesnikov AV, Abdulaev RA, Reutov AV, Abdulaev IA. [Optimization of early diagnostic methods and surgical treatment of thyroid nodal neoplasm in flying staff]. Voen Med Zh 2006; 327:29-31. [PMID: 17236669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
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45
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Ala-Laurila P, Kolesnikov AV, Crouch RK, Tsina E, Shukolyukov SA, Govardovskii VI, Koutalos Y, Wiggert B, Estevez ME, Cornwall MC. Visual cycle: Dependence of retinol production and removal on photoproduct decay and cell morphology. ACTA ACUST UNITED AC 2006; 128:153-69. [PMID: 16847097 PMCID: PMC2151530 DOI: 10.1085/jgp.200609557] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The visual cycle is a chain of biochemical reactions that regenerate visual pigment following exposure to light. Initial steps, the liberation of all-trans retinal and its reduction to all-trans retinol by retinol dehydrogenase (RDH), take place in photoreceptors. We performed comparative microspectrophotometric and microfluorometric measurements on a variety of rod and cone photoreceptors isolated from salamander retinae to correlate the rates of photoproduct decay and retinol production. Metapigment decay rate was spatially uniform within outer segments and 50-70 times faster in the cells that contained cone-type pigment (SWS2 and M/LWS) compared to cells with rod-type pigment (RH1). Retinol production rate was strongly position dependent, fastest at the base of outer segments. Retinol production rate was 10-40 times faster in cones with cone pigments (SWS2 and M/LWS) than in the basal OS of rods containing rod pigment (RH1). Production rate was approximately five times faster in rods containing cone pigment (SWS2) than the rate in basal OS of rods containing the rod pigment (RH1). We show that retinol production is defined either by metapigment decay rate or RDH reaction rate, depending on cell type or outer segment region, whereas retinol removal is defined by the surface-to-volume ratio of the outer segment and the availability of retinoid binding protein (IRBP). The more rapid rates of retinol production in cones compared to rods are consistent with the more rapid operation of the visual cycle in these cells.
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Affiliation(s)
- Petri Ala-Laurila
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118, USA.
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Kolesnikov AV, Shukolyukov SA, Cornwall MC, Govardovskii VI. Recombination reaction of rhodopsin in situ studied by photoconversion of “indicator yellow”. Vision Res 2006; 46:1665-75. [PMID: 16153675 DOI: 10.1016/j.visres.2005.07.032] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2005] [Revised: 07/21/2005] [Accepted: 07/28/2005] [Indexed: 11/17/2022]
Abstract
We measured the kinetics of recombination of 11-cis-retinal with opsin in intact frog rod outer segment (ROS). The rhodopsin in ROS was bleached and allowed to decay to "indicator yellow," a photoproduct where all-trans-retinal is partly free, and partly bound to non-specific amino groups of disk membranes. By briefly illuminating the "indicator yellow" by an intense 465 or 380-nm flash, we then photoconverted all-trans-retinal to (mostly) the 11-cis- form thus introducing into ROS a certain amount of cis-chromophore. The recombination of cis-retinal with opsin and the formation of rhodopsin were followed by fast single-cell microspectrophotometry. Regeneration proceeded with a time constant of approximately 3.5 min; up to 27% of bleached visual pigment was restored. The regenerated pigment consisted of 91% rhodopsin (11-cis-chromophore) and 9% of presumably isorhodopsin (9-cis-chromophore). The recombination of 11-cis-retinal with opsin inside the ROS proceeds substantially faster than rhodopsin regeneration in the intact eye and, hence, is not the rate-limiting step in the visual cycle.
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Affiliation(s)
- A V Kolesnikov
- Institute for Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, 194223 St. Petersburg, Russia
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Abstract
The recovery of rod responsiveness after saturating flashes is greatly retarded above a certain critical level of rhodopsin bleaching (approximately 0.1%). A mathematical description of the process of turn-off of the phototransduction cascade allows attributing different phases of the recovery to specific products of rhodopsin photolysis. The fast phase is determined by quenching of metarhodopsin II and activated transducin. The slow phase is controlled by decay of partially inactivated (phosphorylated and arrestin-bound) metarhodopsins, and by regeneration of rhodopsin. The transition between the two regimes of adaptation is rather abrupt, occurring within a few-fold range of stimulus intensity. This marks the border between reversal of light adaptation and dark adaptation, as it is commonly defined.
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Affiliation(s)
- M L Firsov
- Institute for Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, 44 Thorez Prospect, 194223 St. Petersburg, Russia
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Zakharova MY, Kozyr AV, Ignatova AN, Vinnikov IA, Shemyakin IG, Kolesnikov AV. Purification of filamentous bacteriophage for phage display using size-exclusion chromatography. Biotechniques 2005; 38:194, 196, 198. [PMID: 15727124 DOI: 10.2144/05382bm04] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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49
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Kozyr' AV, Bobik TV, Ignatova AN, Kolesnikov AV. [Production of DNA-hydrolyzing antibody BV04-01 Fab fragment in methylotrophic yeast Pichia pastoris]. Mol Biol (Mosk) 2004; 38:1067-75. [PMID: 15612595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
Efficient system for producing the recombinant Fab of DNA-hydrolyzing antibody BV04-01 in metylotrophic yeast Pichia pastoris was developed. Addition of peptides encompassing the Jun-Fos leucine zipper at the C-termini of the antibody chains facilitated the in vivo assembling of the Fab. The yield of secreted functionally active BV04-01 Fab was about 3 mg/L. Catalytic efficiency of supercoiled DNA hydrolysis by the Fab obtained was 1.8 x 10(6) M(-1) min(-1).
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50
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Govardovskiĭ VI, Shukoliukov SA, Kolesnikov AV, Golobkova EI. [Visual cycle and dark adaptation: a new approach in research]. Ross Fiziol Zh Im I M Sechenova 2004; 90:1015-25. [PMID: 15552367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
Visual cycle is the series of reactions that support regeneration of the visual pigmen after its photolysis in retinal rods and cones. Inherited or acquired deficiencies of the visual cycle impair dark adaptation and lead to a series of visual disorders. The paper describes a new approach to study of the visual cycle that uses fast dichroic microspectrophotometer. The method allows studying interconversion of bleaching products in single intact photoreceptors in condition approaching the situation in vivo. Using this approach, we established a complete scheme of transitions between metarhodopsins, retinal and retinol in amphibian rods. It appeared that the decay of metarhodopsins controls both the time course of rod dark adaptation following small bleaches and the production of retinol that is the substrate for rhodopsin regeneration. We also obtained novel data on kinetics of the decay of cone metapigments that was found to be by an order of magnitude faster than in rods. Possible application of the method for further study of the visual cycle in normal and pathological conditions is discussed.
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