Gecko ι-crystallin: How cellular retinol-binding protein became an eye lens ultraviolet filter

Werten, Paul J.L.; Röll, Beate; Aalten, D.M.F. van; Jong, Wilfried W. de

doi:10.1073/pnas.97.7.3282

Cited by 11 publications

(5 citation statements)

References 41 publications

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“…Sphaerodactylus and Narudasia have lens crystallin composition similar to nocturnal geckos (Röll, ). However, many other diurnal genera have recruited the CRBPI protein to bind with 3,4‐didehydroretinol (vitamin A 2 ) to filter harmful ultraviolet light (Werten, Roll, van Aalten & de Jong, ). The presence of CRBPI in the lens is unique to Lygodactylus , Phelsuma , Pristurus , Gonatodes , Quedenfeldtia and African Cnemaspis , and is not found in the lenses of any other vertebrates (Röll, Amons & deJong, ; Röll & Schwemer, ; Röll, ).…”

Section: Discussionmentioning

confidence: 99%

Into the light: diurnality has evolved multiple times in geckos

Gamble

Greenbaum

Jackman

et al. 2015

Biol J Linn Soc Lond

141

148

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Geckos are the only major lizard group consisting mostly of nocturnal species. Nocturnality is presumed to have evolved early in gecko evolution and geckos possess numerous adaptations to functioning in low light and at low temperatures. However, not all gecko species are nocturnal and most diurnal geckos have their own distinct adaptations to living in warmer, sunlit environments. We reconstructed the evolution of gecko activity patterns using a newly generated time‐calibrated phylogeny. Our results provide the first phylogenetic analysis of temporal activity patterns in geckos and confirm an ancient origin of nocturnality at the root of the gecko tree. We identify multiple transitions to diurnality at a variety of evolutionary time scales and transitions back to nocturnality occur in several predominantly diurnal clades. The scenario presented here will be useful in reinterpreting existing hypotheses of how geckos have adapted to varying thermal and light environments. These results can also inform future research of gecko ecology, physiology, morphology and vision as it relates to changes in temporal activity patterns. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, ●●, ●●–●●.

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Section: Discussionmentioning

confidence: 99%

Into the light: diurnality has evolved multiple times in geckos

Gamble

Greenbaum

Jackman

et al. 2015

Biol J Linn Soc Lond

141

148

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“…For example, the lenses of diurnal geckos that are exposed to high light intensities accumulate -crystallin, a cellular retinol-binding protein type 1 adapted to bind vitamin A 2 . 30,31 In addition to presumably affecting the refractive index of the lens, the -crystallin-vitamin A 2 complex is thought to protect the retina by absorbing shortwave radiation. By analogy with the dual roles of lens crystallins, ALDH3 may protect against oxidative damage of light-induced lipid peroxidations and absorption of ultraviolet light in the mammalian cornea.…”

Section: Function Of the Abundant Water-soluble Intracellular Cornealmentioning

confidence: 99%

“…In the lens, the ␣-crystallins were recruited from ubiquitous, nonenzymatic small heatshock proteins, 6 and -crystallin was recruited from cellular retinol-binding protein in geckos. 30,31 In the cornea, gelsolin is the predominant water-soluble, intracellular protein in the corneas of some fish. 24…”

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confidence: 99%

Enigma of the Abundant Water-Soluble Cytoplasmic Proteins of the Cornea

Piatigorsky

2001

Cornea

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It is accepted that the taxon-specific, multifunctional crystallins (small heat-shock proteins and enzymes) serve structural roles contributing to the transparent and refractive properties of the lens. The transparent cornea also accumulates unexpectedly high proportions of taxon-specific, multifunctional proteins particularly, but not only, in the epithelium. For example, aldehyde dehydrogenase 3 (ALDH3) is the main water-soluble protein in corneal epithelial cells of most mammals (but ALDH1 predominates in the rabbit), whereas gelsolin predominates in the zebrafish corneal epithelium. Moreover, some invertebrates (e.g., squid and scallop) accumulate proteins in their corneas that are similar to their lens crystallins. Pax-6, among other transcription factors, is implicated in development and tissue-specific gene expression of the lens and cornea. Environmental factors appear to influence gene expression in the cornea, but not the lens. Although no direct proof exists, the diverse, abundant corneal proteins may have evolved a crystallinlike role, in addition to their enzymatic or cytoskeletal functions, by a gene sharing mechanism similar to the lens crystallins. Consequently, it is proposed that the cornea and lens be considered as a single refractive unit, called here the "refracton," to emphasize their similarities and common function.

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“…It is noteworthy in this connection that homologies have been noted between peptides of a human kidney thyroid hormone-binding protein (71) and -crystallin, an enzymatically inactive kangaroo lens enzyme-crystallin homologous to bacterial ornithine cyclodeaminase (75). The binding of 3,4-didehydroretinol by -crystallin, a crystallin related to cellular retinolbinding protein type 1, to create an ultraviolet filter in lenses of diurnal geckos is a striking case of the importance of a crystallin binding a ligand for a biological function (76).…”

Section: Discussionmentioning

confidence: 99%

Ω-Crystallin of the Scallop Lens

Piatigorsky¹,

Kozmík²,

Horwitz³

et al. 2000

Journal of Biological Chemistry

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While many of the diverse crystallins of the transparent lens of vertebrates are related or identical to metabolic enzymes, much less is known about the lens crystallins of invertebrates. Here we investigate the complex eye of scallops. Electron microscopic inspection revealed that the anterior, single layered corneal epithelium overlying the cellular lens contains a regular array of microvilli that we propose might contribute to its optical properties. The sole crystallin of the scallop eye lens was found to be homologous to ⍀-crystallin, a minor crystallin in cephalopods related to aldehyde dehydrogenase (ALDH) class 1/2. Scallop ⍀-crystallin (officially designated ALDH1A9) is 55-56% identical to its cephalopod homologues, while it is 67 and 64% identical to human ALDH 2 and 1, respectively, and 61% identical to retinaldehyde dehydrogenase/-crystallin of elephant shrews. Like other enzyme-crystallins, scallop ⍀-crystallin appears to be present in low amounts in nonocular tissues. Within the scallop eye, immunofluorescence tests indicated that ⍀-crystallin expression is confined to the lens and cornea. Although it has conserved the critical residues required for activity in other ALDHs and appears by homology modeling to have a structure very similar to human ALDH2, scallop ⍀-crystallin was enzymatically inactive with diverse substrates and did not bind NAD or NADP. In contrast to mammalian ALDH1 and -2 and other cephalopod ⍀-crystallins, which are tetrameric proteins, scallop ⍀-crystallin is a dimeric protein. Thus, ALDH is the most diverse lens enzyme-crystallin identified so far, having been used as a lens crystallin in at least two classes of molluscs as well as elephant shrews.

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Gecko ι-crystallin: How cellular retinol-binding protein became an eye lens ultraviolet filter

Cited by 11 publications

References 41 publications

Into the light: diurnality has evolved multiple times in geckos

Into the light: diurnality has evolved multiple times in geckos

Enigma of the Abundant Water-Soluble Cytoplasmic Proteins of the Cornea

Ω-Crystallin of the Scallop Lens

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