Disturbing Gtp-Binding Protein Function Through Microinjection Into The Visual Cell Of Limulus

Stieve, H.; Niemeyer, Barbara A.; Aktories, Klaus; Hamm, Heidi E.

doi:10.1515/znc-1992-11-1220

Cited by 11 publications

(5 citation statements)

References 16 publications

(21 reference statements)

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“…Several reports have now clearly shown a role for the small GTP-binding proteins of the rho class in the modulation of the actin cytoskeleton (for review see Nobes and Hall, 1994; also see the Introduction). A functional role for small GTP-binding proteins in phototransduction has also been suggested in squid and bovine photoreceptors (Wieland et al, 1990;Petrov et al, 1994) and Limulus photoreceptors (Stieve et al, 1992). Small GTP-binding proteins of the rab family are critical for the intracellular transport of rhodopsin-containing vesicles (Deretic and Papermaster, 1993).…”

Section: Discussionmentioning

confidence: 98%

In vivo requirement of protein prenylation for maintenance of retinal cytoarchitecture and photoreceptor structure.

Pittler

Fliesler

Fisher

et al. 1995

The Journal of Cell Biology

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Abstract. Recent studies have demonstrated that inhibition of mevalonate synthesis in cultured cells leads to altered cell morphology due to inhibition of protein prenylation. To investigate the effects in vivo of mevalonate deprivation in nondividing, terminally differentiated neural cells, we have analyzed the effects on retinal tissue of intravitreal injection of lovastatin, a potent inhibitor of the mevalonate-producing enzyme, HMGCoA reductase. A single injection of lovastatin (0.25 ~mol) produced profound dysplastic-like changes in adult rat retinas primarily involving the photoreceptor layer. Within 2 d after injection, photoreceptor nuclei migrated in a circular pattern resulting in the formation of rosette-like structures by 4 d. Also during this period, photoreceptor inner and outer segment degeneration was evident. By 21 d, intact photoreceptor nuclei with remnants of inner and outer segments were dispersed throughout all retinal layers. To investigate the biochemical specificity of the lovastatin-induced alterations, and to distinguish the relative importance of the various branches of the mevalonate pathway, the incorpoTation of [3H]acetate into retinal lipids was examined in the presence and absence of metabolic inhibitors. HPLC analysis of lovastatin-treated retinas revealed a dramatic reduction in the incorporation of intravitreally injected [3H]acetate into nonsaponifiable lipids, compared with controls. In contrast, intravitreal injection of NB-598, a specific inhibitor of squalene epoxidase, eliminated the conversion of newly synthesized squalene to sterols without obvious pathology. Hence, involvement of the sterol branch of isoprenoid metabolism in the lovastatin-induced morphologic disruption was obviated. Intravitreal injection of 0.27 ixmol of N-acetyl-S-trans,trans-farnesyl-L-cysteine (AFC), an inhibitor of carboxyl methyltransferase activity and prenylated protein function, produced morphologic changes that were virtually indistinguishable from those induced with lovastatin. These results implicate a defect in protein prenylation in the lovastatin-induced retinal degeneration, and suggest the presence of a dynamic pathway in the retina that requires isoprenylated proteins to maintain retinal cytoarchitecture.

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Section: Discussionmentioning

confidence: 98%

In vivo requirement of protein prenylation for maintenance of retinal cytoarchitecture and photoreceptor structure.

Pittler

Fliesler

Fisher

et al. 1995

The Journal of Cell Biology

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“…Therefore, Rho is considered to be involved in the photosensitive melanophore response as a signal transducer. In visual cells, a small (20-30 kDa) GTP-binding protein is also reported to contribute to signal transduction in visual cells in addition to Gt (59)(60)(61). Again, it is speculated that the light-induced response of Xenopus tadpole melanophores may be regulated by molecular mechanisms similar to those of photon signal transduction in visual cells (58).…”

Section: Signaling Pathway In the Action Of Light On Chromatophoresmentioning

confidence: 99%

Direct Reception of Light by Chromatophores of Lower Vertebrates

Oshima

2001

Pigment Cell Research

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Rapid color changes of lower vertebrates are caused by the motile activities of pigment cells (chromatophores) present in the skin tissue. Chromatophore motility is generally regulated by neural and/or by endocrine systems. However, in some cases, light also induces pigment aggregation or dispersion directly, which suggests the existence of visual pigments in chromatophores. In fact, some opsins, including melanopsin, have been identified. This article reviews light‐sensitive chromatophores of lower vertebrates. Photoreceptive molecules (visual pigments) and signal transduction of light via a GTP‐binding protein (G protein) are also discussed.

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“…The same antibody only very weakly labeled electron-microscopic sections of cuttlefish photoreceptor cells (Schraermeyer et al, 1995). On the other hand, in Limulus ventral photoreceptors, the microinjection of a monoclonal antibody against the a-subunit of transducin reduced the amplitude of the light-evoked receptor current (Stieve et al, 1992). These observations indicate that if additional types of G-protein are involved in the phototransduction of Limulus and Sepia, they might not have much sequence homology with the GTP-binding core of transducin.…”

Section: Discussionmentioning

confidence: 94%

“…Microinjections of the non-hydrolyzable GDP analog GDP-/3-S suppressed dose dependently the light response of this preparation (Fein, 1986;Stieve et al, 1992), and the injection of antibody directed against the a-subunit of G q blocked one component of the light-induced receptor current . Microinjections of the non-hydrolyzable GDP analog GDP-/3-S suppressed dose dependently the light response of this preparation (Fein, 1986;Stieve et al, 1992), and the injection of antibody directed against the a-subunit of G q blocked one component of the light-induced receptor current .…”

Section: Introductionmentioning

confidence: 90%

“…Electrophysiological studies on the role of G-proteins in phototransduction were mainly done in the Limulus ventral photoreceptor. Microinjections of the non-hydrolyzable GDP analog GDP-/3-S suppressed dose dependently the light response of this preparation (Fein, 1986;Stieve et al, 1992), and the injection of antibody directed against the a-subunit of G q blocked one component of the light-induced receptor current . However, only a few biochemical studies on these photoreceptors are available, and with the exception of a preliminary report (Schremser et al, 1995) direct biochemical or immunocytochemical evidence for the existence of G q in Limulus photoreceptors is lacking.…”

Section: Introductionmentioning

confidence: 90%

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Immunological demonstration of G_q-protein inLimulusphotoreceptors

1997

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The phototransduction cascade in invertebrates involves the coupling of rhodopsin activation to the action of the enzyme phospholipase C. This step is performed by G-proteins. An antibody against the a-subunit of a mouse G q type G-protein recognized protein bands in Western blots of lateral eye and ventral nerve photoreceptors of Limulus. The protein bands had an apparent molecular mass of about 42 kDa. The antibody also recognized protein bands of a similar molecular mass in immunoblots of brain and intestine tissue. Immunoreactivity was found in lateral eye frozen sections where it was confined to the rhabdom region. When the antibody was applied to ultrathin sections of ventral nerve photoreceptors, the highest density of labeling was found on the rhabdomeral microvilli, but gold particles were also scattered in the cytoplasm. We conclude that a G-protein of the type G q participates in the phototransduction of Limulus.

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Disturbing Gtp-Binding Protein Function Through Microinjection Into The Visual Cell Of Limulus

Cited by 11 publications

References 16 publications

In vivo requirement of protein prenylation for maintenance of retinal cytoarchitecture and photoreceptor structure.

In vivo requirement of protein prenylation for maintenance of retinal cytoarchitecture and photoreceptor structure.

Direct Reception of Light by Chromatophores of Lower Vertebrates

Immunological demonstration of G_q-protein inLimulusphotoreceptors

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Disturbing Gtp-Binding Protein Function Through Microinjection Into The Visual Cell Of Limulus

Cited by 11 publications

References 16 publications

In vivo requirement of protein prenylation for maintenance of retinal cytoarchitecture and photoreceptor structure.

In vivo requirement of protein prenylation for maintenance of retinal cytoarchitecture and photoreceptor structure.

Direct Reception of Light by Chromatophores of Lower Vertebrates

Immunological demonstration of Gq-protein inLimulusphotoreceptors

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Immunological demonstration of G_q-protein inLimulusphotoreceptors