Puzzle of crystallin diversity in eye lenses

Piatigorsky, Joram

doi:10.1002/aja.1001960408

Cited by 51 publications

(20 citation statements)

References 40 publications

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“…Although not an enzyme, ι-crystallin has been co-opted from another function for its optical role in the lens. This crystallin hallmark of being recruited from proteins with ubiquitous metabolic functions has led to the idea that crystallins are unified less by their protein phenotype than by their mode of high, lenspreferred gene expression (Carosa et al, 2002, Piatigorsky, 1993, Piatigorsky and Wistow, 1991. We have called the dual use of a single protein encoded in one gene, 'gene sharing' Wistow, 1989).…”

Section: A B C D E F B Amentioning

confidence: 99%

Cubozoan jellyfish: an Evo/Devo model for eyes and other sensory systems

Piatigorsky

Kozmík²

2004

Int. J. Dev. Biol.

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Cnidaria are the most basal phylum containing a well-developed visual system located on specialized sensory structures (rhopalia) with eyes and statocyts. We have been exploring the cubozoan jellyfish, Tripedalia cystophora. In addition to containing simple photoreceptive ocelli, each rhopalium in Tridedalia has a large and small complex, camera-type eye with a cellular lens containing three distinct families of crystallins which apparently serve non-lenticular functions. Thus, Tridpedalia recruited crystallins by a gene sharing strategy as have mollusks and vertebrates. Tripedalia has a single Pax gene, PaxB, which encodes a structural and functional Pax 2/5/8-like paired domain as well as an octapeptide and Pax6-like homeodomain. PaxB binds to and activates Tripedalia crystallin promoters (especially J3-crystallin) and the Drosophila rhodopsin rh6 gene in transfection tests and induces ectopic eyes in Drosophila. In situ hybridization showed that PaxB and crystallin genes are expressed in the lens, retina and statocysts. We suggest from these results that an ancestral PaxB gene was a primordial gene in eye evolution and that eyes and ears (mechanoreceptors) may have had a common evolutionary origin. Thus, the numerous structural and molecular features of Tridpalia rhopalia indicate that ancient cubozoan jellyfish are fascinating models for evo/devo insights into eyes and other sensory systems.

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Section: A B C D E F B Amentioning

confidence: 99%

Cubozoan jellyfish: an Evo/Devo model for eyes and other sensory systems

Piatigorsky

Kozmík²

2004

Int. J. Dev. Biol.

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“…From the definition of inductive interactions in development (Spemann, 1901), to the unfolding of a fascinating tale of evolution with the characterization of the lens crystallins (Piatigorsky, 1993) and the identification of ocular immune privilege and its mediators (Streilein, 1993), the vertebrate eye has yielded many insights into biological processes. It is difficult to imagine that the pace of discovery will slow given the enduring attraction of this organ as an object of investigation.…”

Section: Future Perspectivesmentioning

confidence: 99%

Apoptosis in mammalian eye development: lens morphogenesis, vascular regression and immune privilege

Lang

1997

Cell Death Differ

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Formation of the mammalian eye requires a complex series of tissue interactions that result in an organ of exquisite sensory capability. The early steps in eye development involve extensive cell death associated with morphogenesis. Later, suppression of programmed cell death is essential for tissue differentiation and in the adult, the immune privileged status of the eye is maintained in part through factors that induce inflammatory cell apoptosis. Experimental evidence suggests that suppression of apoptosis in cells of the lens lineage by fibroblast growth factors is one component of their action during lens morphogenesis. Fibroblast growth factors are also required for normal lens fiber-cell differentiation. This includes a degenerative step for organelles that is presumably an adaptation for the clearance of light scattering elements from the optic axis. The process of organelle degeneration may be related to apoptosis in a few of its features. Activelyinduced apoptosis becomes important for eye development as the temporary ocular vasculatures regress. This too, is presumably an adaptation for the disposal of cells that would disturb the passage of light to the retina. Ocular macrophages appear to be essential for the induction of apoptosis in the endothelial cells comprising the ocular vasculatures. In the adult, inflammatory cells entering the eye are exposed to the pro-apoptotic agents transforming growth factor-b2 and Fas ligand. The expression of these molecules in the eye, and their action in killing inflammatory cells, has evolved as a means of preventing inflammation and subsequent loss of vision. Thus, the eye offers a unique and versatile system for studying the role of programmed cell death in lens development, vascular regression and immune privilege.

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“…Therefore, it is possible that AP may function as a structural molecule rather than an enzyme. This situation would be analogous to that of the lens crystallins where structural molecules can be identical to some enzymes (Piatigorsky and Wistow, 1989;Piatigorsky, 1993). Therefore, whether chicken TNAP functions as an enzyme to loosen cell adhesive connections permitting cell migration, or provides a signal or scaffold for cells to migrate by, is yet to be determined.…”

Section: Discussionmentioning

confidence: 99%

Tissue‐nonspecific alkaline phosphatase participates in the establishment and growth of feather germs in embryonic chick skin cultures

Crawford

Weissig

Binette

et al. 1995

Developmental Dynamics

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Alkaline phosphatase activity is present in the mesoderm of embryonic chick skin and becomes spatially restricted to the dermal condensation of the developing feather germs. Inhibitors to tissue-nonspecific (liver/bone/kidney), but not intestinal, alkaline phosphatase inhibit the establishment and growth of feather germs in cultured skins. A window of maximum sensitivity to the inhibitor was observed to be the first day of culture when early development and establishment of pattern takes place. The cDNA for the avian tissue-nonspecific alkaline phosphatase was cloned and sequenced, and Southern analysis revealed a single copy of this gene in the avian genome. Northern analysis revealed that a 2.8 kb transcript for this form of alkaline phosphatase is present in developing skin. o 1995 Wiley-Liss, Inc.

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Puzzle of crystallin diversity in eye lenses

Cited by 51 publications

References 40 publications

Cubozoan jellyfish: an Evo/Devo model for eyes and other sensory systems

Cubozoan jellyfish: an Evo/Devo model for eyes and other sensory systems

Apoptosis in mammalian eye development: lens morphogenesis, vascular regression and immune privilege

Tissue‐nonspecific alkaline phosphatase participates in the establishment and growth of feather germs in embryonic chick skin cultures

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