Biomaterial Database

Messenger RNA for cataractous lens proteins are also present on normal lens polyribosomes. 1980

J C Weill, and G Leca, and A Vincent, and O Civelli, and Y Pouliquen

We have previously described an experimental model in vivo where cataract is induced by injection of the antimitotic bleomycin in the newborn rat. The first opacity of the lens appears 12--15 days after the injection of the drug concomitantly with a group of precise biochemical modifications among the soluble crystallins. These modifications are mainly the accumulation of two additional low-molecular-weight beta crystallin subunits (beta L subunits) and of several smaller alpha-crystallin polypeptides. Messenger RNA isolated from normal and cataractous lenses was assayed for translation in a cell-free wheat germ extract. Analysis of the translation products by one-dimensional and two-dimensional gel electrophoresis indicated that the messenger RNAs coding for the two beta L subunits are also present on normal lens polyribosomes. Purification and subsequent analysis by peptide mapping of the cataractous Beta L subunits suggest that they are precursor polypeptides of the normal low-molecular-weight beta-crystallins, which are no longer processed after translation and therefore accumulate in the pathological lens cell. On the other hand, in the translation of the cataractous mRNA in vitro, only the normal alpha chains are detected. These cataractous alpha-crystallins are therefore post-translational degradation products of the normal alpha polypeptides. This phenomenon seems similar to the one observed in the senescent lens. The possible involvement of these modifications in the etiology of this experimental cataract is discussed further.

UI	MeSH Term	Description	Entries
D007908	Lens, Crystalline	A transparent, biconvex structure of the EYE, enclosed in a capsule and situated behind the IRIS and in front of the vitreous humor (VITREOUS BODY). It is slightly overlapped at its margin by the ciliary processes. Adaptation by the CILIARY BODY is crucial for OCULAR ACCOMMODATION.	Eye Lens,Lens, Eye,Crystalline Lens
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D010455	Peptides	Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are considered to be larger versions of peptides that can form into complex structures such as ENZYMES and RECEPTORS.	Peptide,Polypeptide,Polypeptides
D011132	Polyribosomes	A multiribosomal structure representing a linear array of RIBOSOMES held together by messenger RNA; (RNA, MESSENGER); They represent the active complexes in cellular protein synthesis and are able to incorporate amino acids into polypeptides both in vivo and in vitro. (From Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)	Polysomes,Polyribosome,Polysome
D001761	Bleomycin	A complex of related glycopeptide antibiotics from Streptomyces verticillus consisting of bleomycin A2 and B2. It inhibits DNA metabolism and is used as an antineoplastic, especially for solid tumors.	BLEO-cell,Blanoxan,Blenoxane,Bleolem,Bleomicina,Bleomycin A(2),Bleomycin A2,Bleomycin B(2),Bleomycin B2,Bleomycin Sulfate,Bleomycins,Bleomycinum Mack,Bléomycine Bellon,BLEO cell,BLEOcell,Bellon, Bléomycine,Mack, Bleomycinum,Sulfate, Bleomycin
D002386	Cataract	Partial or complete opacity on or in the lens or capsule of one or both eyes, impairing vision or causing blindness. The many kinds of cataract are classified by their morphology (size, shape, location) or etiology (cause and time of occurrence). (Dorland, 27th ed)	Cataract, Membranous,Lens Opacities,Pseudoaphakia,Cataracts,Cataracts, Membranous,Lens Opacity,Membranous Cataract,Membranous Cataracts,Opacities, Lens,Opacity, Lens,Pseudoaphakias
D003459	Crystallins	A heterogeneous family of water-soluble structural proteins found in cells of the vertebrate lens. The presence of these proteins accounts for the transparency of the lens. The family is composed of four major groups, alpha, beta, gamma, and delta, and several minor groups, which are classed on the basis of size, charge, immunological properties, and vertebrate source. Alpha, beta, and delta crystallins occur in avian and reptilian lenses, while alpha, beta, and gamma crystallins occur in all other lenses.	Lens Proteins,Crystallin,Eye Lens Protein,Lens Protein, Eye,Protein, Eye Lens,Proteins, Lens
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D012333	RNA, Messenger	RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.	Messenger RNA,Messenger RNA, Polyadenylated,Poly(A) Tail,Poly(A)+ RNA,Poly(A)+ mRNA,RNA, Messenger, Polyadenylated,RNA, Polyadenylated,mRNA,mRNA, Non-Polyadenylated,mRNA, Polyadenylated,Non-Polyadenylated mRNA,Poly(A) RNA,Polyadenylated mRNA,Non Polyadenylated mRNA,Polyadenylated Messenger RNA,Polyadenylated RNA,RNA, Polyadenylated Messenger,mRNA, Non Polyadenylated
D014176	Protein Biosynthesis	The biosynthesis of PEPTIDES and PROTEINS on RIBOSOMES, directed by MESSENGER RNA, via TRANSFER RNA that is charged with standard proteinogenic AMINO ACIDS.	Genetic Translation,Peptide Biosynthesis, Ribosomal,Protein Translation,Translation, Genetic,Protein Biosynthesis, Ribosomal,Protein Synthesis, Ribosomal,Ribosomal Peptide Biosynthesis,mRNA Translation,Biosynthesis, Protein,Biosynthesis, Ribosomal Peptide,Biosynthesis, Ribosomal Protein,Genetic Translations,Ribosomal Protein Biosynthesis,Ribosomal Protein Synthesis,Synthesis, Ribosomal Protein,Translation, Protein,Translation, mRNA,mRNA Translations