Up‐regulation of novel intermediate filament proteins in primary fiber cells: An indicator of all vertebrate lens fiber differentiation?

The early embryonic development and expression patterns of the eye lens specific cytoskeletal proteins, CP49 and CP95, were determined for the chick and were found to be similar in both human and mouse. These proteins, as well as their homologs in other species, are obligate polymerization partners which form unique filamentous structures termed “beaded filaments.” CP49 and CP95 appeared as protein products after 3 days of embryonic development in the chick during the elongation of primary fiber cells. Although limited data were obtained for human embryos at these early developmental timepoints, they were consistent with the interpretation that the up‐regulation of these lens specific proteins began only after the initiation of lens vesicle closure. In situ hybridization with the mouse lens confirmed that message levels for beaded filament proteins were greatly elevated in differentiating primary fiber cells. Nuclease protection assays established that mRNA levels for CP49 remained relatively constant while CP95 mRNA levels increased once the process of secondary fiber formation was under way. Although present in relatively low abundance, the mRNA for a unique splice variant of CP49, CP49INS, was also detected early in embryonic development and into adulthood. Peptide‐specific antibodies directed against unique predicted sequences were able to confirm the protein expression of CP49INS in both embryonic and adult chick lens cells. These data present the first detailed study of the expression of CP49 and CP95 during early lens development. They suggest that the up‐regulated expression of CP49 and CP95 could serve as pan‐specific markers for all vertebrate lens fiber development. Anat Rec 258:25–33, 2000. © 2000 Wiley‐Liss, Inc.

[1]  A. Prescott,et al.  Gap junctions containing alpha8-connexin (MP70) in the adult mammalian lens epithelium suggests a re-evaluation of its role in the lens. , 1999, Experimental eye research.

[2]  J. Hess,et al.  Primary sequence, secondary structure, gene structure, and assembly properties suggests that the lens-specific cytoskeletal protein filensin represents a novel class of intermediate filament protein. , 1998, Experimental eye research.

[3]  D. Burt,et al.  The chicken CP49 gene contains an extra exon compared to the human CP49 gene which identifies an important step in the evolution of the eye lens intermediate filament proteins. , 1998, Gene.

[4]  E. Fuchs,et al.  A structural scaffolding of intermediate filaments in health and disease. , 1998, Science.

[5]  P. Lichter,et al.  The mouse filensin gene: structure and evolutionary relation to other intermediate filament genes , 1997, FEBS letters.

[6]  M. Wride.  Cellular and molecular features of lens differentiation: a review of recent advances. , 1996, Differentiation; research in biological diversity.

[7]  H. Naegeli,et al.  Recognition of DNA Adducts by Human Nucleotide Excision Repair , 1996, The Journal of Biological Chemistry.

[8]  A. Prescott,et al.  The beaded filament of the eye lens: an unexpected key to intermediate filament structure and function. , 1996, Trends in cell biology.

[9]  J. Hess,et al.  Gene Structure and cDNA Sequence Identify the Beaded Filament Protein CP49 as a Highly Divergent Type I Intermediate Filament Protein (*) , 1996, The Journal of Biological Chemistry.

[10]  S. Müller,et al.  Filensin and phakinin form a novel type of beaded intermediate filaments and coassemble de novo in cultured cells , 1996, The Journal of cell biology.

[11]  G. Eguchi,et al.  The predicted structure of chick lens CP49 and a variant thereof, CP49ins, the first vertebrate cytoplasmic intermediate filament protein with a lamin-like insertion in helix 1B. , 1995, Current eye research.

[12]  D. Goodenough,et al.  Changes in connexin expression and distribution during chick lens development. , 1995, Developmental biology.

[13]  P. Fitzgerald,et al.  Vimentin and CP49/filensin form distinct networks in the lens which are independently modulated during lens fibre cell differentiation. , 1995, Journal of cell science.

[14]  J. M. Carter,et al.  In vitro studies on the assembly properties of the lens proteins CP49, CP115: coassembly with alpha-crystallin but not with vimentin. , 1995, Experimental eye research.

[15]  A. Henkel,et al.  Quantification of proteins dissolved in an electrophoresis sample buffer. , 1994, Analytical biochemistry.

[16]  J. Ralton,et al.  Identification of two N-terminal non-alpha-helical domain motifs important in the assembly of glial fibrillary acidic protein. , 1994, Journal of cell science.

[17]  D. Paul,et al.  Molecular cloning and functional characterization of chick lens fiber connexin 45.6. , 1994, Molecular biology of the cell.

[18]  A. Merdes,et al.  The 47-kD lens-specific protein phakinin is a tailless intermediate filament protein and an assembly partner of filensin , 1993, The Journal of cell biology.

[19]  S. Remington,et al.  Chicken filensin: a lens fiber cell protein that exhibits sequence similarity to intermediate filament proteins. , 1993, Journal of cell science.

[20]  G. Wistow,et al.  Lens crystallins: gene recruitment and evolutionary dynamism. , 1993, Trends in biochemical sciences.

[21]  C. Ouzounis,et al.  Bovine filensin possesses primary and secondary structure similarity to intermediate filament proteins , 1993, The Journal of cell biology.

[22]  C. Klettner,et al.  Cyclic AMP-mediated phosphorylation and insolubilization of a 49-kDa cytoskeletal marker protein of lens fiber terminal differentiation. , 1993, Experimental eye research.

[23]  R. Grainger.  Embryonic lens induction: shedding light on vertebrate tissue determination. , 1992, Trends in genetics : TIG.

[24]  H. Horstmann,et al.  Filensin: a new vimentin-binding, polymerization-competent, and membrane-associated protein of the lens fiber cell , 1991, The Journal of cell biology.

[25]  T. Watanabe,et al.  Defect of a fiber cell-specific 94-kDa protein in the lens of inherited microphthalmic mutant mouse Elo. , 1991, Biochemical and biophysical research communications.

[26]  P. Fitzgerald,et al.  Immunologic conservation of the fiber cell beaded filament. , 1991, Current eye research.

[27]  M. Ireland,et al.  Initial characterization of lens beta-adrenergic receptors. , 1989, Investigative ophthalmology & visual science.

[28]  J. Piatigorsky.  Lens crystallins and their genes: diversity and tissue‐specific expression , 1989, FASEB journal : official publication of the Federation of American Societies for Experimental Biology.

[29]  G. Milligan,et al.  Antibodies directed against synthetic peptides distinguish between GTP-binding proteins in neutrophil and brain. , 1987, The Journal of biological chemistry.

[30]  J. McAvoy,et al.  Localisation of laminin and fibronectin during rat lens morphogenesis. , 1984, Differentiation; research in biological diversity.

[31]  H. Maisel,et al.  A cytoskeletal protein unique to lens fiber cell differentiation. , 1984, Experimental eye research.

[32]  H. Maisel,et al.  Identification of native actin filaments in chick lens fiber cells. , 1983, Experimental eye research.

[33]  H. Towbin,et al.  Electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets: procedure and some applications. , 1979, Proceedings of the National Academy of Sciences of the United States of America.

[34]  J. Mcavoy.  Cell division, cell elongation and the co-ordination of crystallin gene expression during lens morphogenesis in the rat. , 1978, Journal of embryology and experimental morphology.

[35]  P. O’Farrell.  High resolution two-dimensional electrophoresis of proteins. , 1975, The Journal of biological chemistry.

[36]  T. Kuwabara.  The maturation of the lens cell: a morphologic study. , 1975, Experimental eye research.

[37]  M. Perry,et al.  Electron microscope observations on some structural proteins of the chick lens. , 1972, Experimental eye research.

[38]  U. K. Laemmli,et al.  Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4 , 1970, Nature.

[39]  S. Modak,et al.  DNA synthesis and mitotic activity during early development of chick lens. , 1968, Developmental biology.

[40]  T. Wanko,et al.  Electron Microscope Study of Lens Fibers , 1959, The Journal of biophysical and biochemical cytology.

[41]  D. Goebel,et al.  Quantification and regulation of mRNAs encoding beaded filament proteins in the chick lens. , 1997, Current eye research.

[42]  P. Fitzgerald,et al.  Filensin is proteolytically processed during lens fiber cell differentiation by multiple independent pathways. , 1995, European journal of cell biology.

[43]  C. Louis,et al.  Cell-to-cell communication in a differentiating ovine lens culture system. , 1994, Investigative ophthalmology & visual science.

[44]  F. Studier,et al.  Use of T7 RNA polymerase to direct expression of cloned genes. , 1990, Methods in enzymology.

[45]  H. Maisel,et al.  A family of lens fiber cell specific proteins. , 1989, Lens and eye toxicity research.

[46]  P. Fitzgerald.  Age-related changes in a fiber cell-specific extrinsic membrane protein. , 1988, Current eye research.

[47]  J. Piatigorsky.  Gene expression and genetic engineering in the lens. Friedenwald lecture. , 1987, Investigative ophthalmology & visual science.

[48]  H. Maisel,et al.  Regional Differences in the Polypeptide Composition of Chick Lens Intracellular Matrix , 1977 .