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  1. Article: Insulin regulates expression of c-fos and c-jun and suppresses apoptosis of lens epithelial cells.

    Rampalli, A M / Zelenka, P S

    Cell growth & differentiation : the molecular biology journal of the American Association for Cancer Research

    1995  Volume 6, Issue 8, Page(s) 945–953

    Abstract: This study investigates whether insulin (a differentiation factor for lens epithelial cells) acts as a survival factor. In the absence of insulin, 6-day embryonic chicken lens epithelial explants undergo apoptosis as shown by changes in cell morphology, ... ...

    Abstract This study investigates whether insulin (a differentiation factor for lens epithelial cells) acts as a survival factor. In the absence of insulin, 6-day embryonic chicken lens epithelial explants undergo apoptosis as shown by changes in cell morphology, DNA fragmentation, and loss of trypan blue exclusion. Insulin inhibits these changes and promotes survival of the cells. Aurintricarboxylic acid suppresses the apoptosis of lens explants. In contrast to 6-day embryonic explants, 19-day embryonic explants survive in the absence of insulin, presumably due to an endogenous survival factor. To explore the mechanism of the action of insulin as a survival factor for 6-day embryonic lens explants, we compared the pattern of cell cycle markers (c-fos, c-jun, c-myc, p53, histone H3, thymidine kinase, and cyclin B) in both apoptotic and differentiating lens explants. In the presence of insulin, the expression of c-fos and c-jun was down-regulated after an initial induction. Expression of these genes was also induced in the absence of insulin, but mRNA levels remained elevated as the cells underwent apoptosis. In contrast, expression of c-myc, p53, histone H3, thymidine kinase, and cyclin B showed only minor differences in differentiating and apoptotic cells. Since c-fos and c-jun have been shown to play a role in apoptosis in other cell types, the ability of insulin to regulate expression of these genes may be central to its ability to act as a survival factor for lens epithelial cells.
    MeSH term(s) Animals ; Apoptosis/drug effects ; Base Sequence ; Cell Differentiation/drug effects ; Cell Survival/drug effects ; Cells, Cultured ; Chick Embryo ; Coloring Agents ; Depression, Chemical ; Epithelial Cells ; Epithelium/drug effects ; Epithelium/metabolism ; Gene Expression Regulation, Developmental/drug effects ; Genes, fos ; Genes, jun ; Insulin/pharmacology ; Lens, Crystalline/cytology ; Lens, Crystalline/drug effects ; Lens, Crystalline/metabolism ; Molecular Sequence Data ; Trypan Blue
    Chemical Substances Coloring Agents ; Insulin ; Trypan Blue (I2ZWO3LS3M)
    Language English
    Publishing date 1995-08
    Publishing country United States
    Document type Journal Article
    ZDB-ID 1034269-2
    ISSN 1044-9523
    ISSN 1044-9523
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 2903: Show issues Location:
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  2. Article: pRb and p107 regulate E2F activity during lens fiber cell differentiation.

    Rampalli, A M / Gao, C Y / Chauthaiwale, V M / Zelenka, P S

    Oncogene

    1998  Volume 16, Issue 3, Page(s) 399–408

    Abstract: During growth arrest and differentiation, activity of the E2F family of transcription factors is inhibited by interactions with pRb and the related proteins, p107 and p130. To determine which members of the E2F and pRb families may contribute to growth ... ...

    Abstract During growth arrest and differentiation, activity of the E2F family of transcription factors is inhibited by interactions with pRb and the related proteins, p107 and p130. To determine which members of the E2F and pRb families may contribute to growth arrest as lens epithelial cells differentiate into fiber cells, we examined the expression of individual E2F species and characterized the E2F protein complexes formed in rat lens epithelia and fibers. RT/PCR detected all five known members of the E2F family in lens epithelial cells, but only E2F-1, E2F-3, and E2F-5 in fiber cells. Proteins extracted from lens epithelia of newborn rats formed at least two specific complexes with an E2F consensus oligonucleotide. Proteins from lens fiber cells formed three specific complexes, one of which comigrated with an epithelial cell complex. Incubation of epithelial and fiber cell extracts with an antibody specific for p107 demonstrated that two fiber cell complexes and one epithelial cell complex contained p107. Although the remaining fiber cell complex did not react with antibodies to pRb or p130 in this assay, a strong reaction with pRb antibody was observed when the electromobility shifted complexes were subsequently immunoblotted (shift/Western assay). Immunocytochemistry confirmed that pRb protein is present in the nuclei of both epithelial cells and fiber cells. Immunoblotting of whole cell extracts with pRb antibody showed multiple, phosphorylated forms of pRb in the epithelial cells, but predominantly hypophosphorylated pRb in the fiber cells. None of the complexes formed with E2F were recognized exclusively by the p130 antibody, although the previously identified p107 complexes reacted weakly. The absence of p130/E2F complexes was correlated with the presence of multiple ubiquitinated forms of p130, especially in the fiber cells. Thus, although p130/E2F complexes are implicated in the terminal differentiation of many cell types, in differentiating lens fiber cells pRb and p107 seem to be the primary regulators of E2F activity.
    MeSH term(s) Animals ; Animals, Newborn ; Carrier Proteins ; Cell Cycle Proteins ; Cell Differentiation ; DNA/metabolism ; DNA-Binding Proteins ; E2F Transcription Factors ; E2F1 Transcription Factor ; E2F3 Transcription Factor ; E2F5 Transcription Factor ; Immunoblotting ; Immunoenzyme Techniques ; Lens, Crystalline/cytology ; Lens, Crystalline/metabolism ; Nuclear Proteins/biosynthesis ; Nuclear Proteins/metabolism ; Phosphoproteins/biosynthesis ; Phosphoproteins/metabolism ; Proteins ; Rats ; Rats, Wistar ; Retinoblastoma Protein/biosynthesis ; Retinoblastoma Protein/metabolism ; Retinoblastoma-Binding Protein 1 ; Retinoblastoma-Like Protein p130 ; Transcription Factor DP1 ; Transcription Factors/biosynthesis ; Transcription Factors/genetics ; Transcription Factors/metabolism ; Ubiquitins/metabolism
    Chemical Substances Carrier Proteins ; Cell Cycle Proteins ; DNA-Binding Proteins ; E2F Transcription Factors ; E2F1 Transcription Factor ; E2F3 Transcription Factor ; E2F5 Transcription Factor ; E2f1 protein, rat ; Nuclear Proteins ; Phosphoproteins ; Proteins ; Rbl2 protein, rat ; Retinoblastoma Protein ; Retinoblastoma-Binding Protein 1 ; Retinoblastoma-Like Protein p130 ; Transcription Factor DP1 ; Transcription Factors ; Ubiquitins ; DNA (9007-49-2)
    Language English
    Publishing date 1998-01-22
    Publishing country England
    Document type Journal Article
    ZDB-ID 639046-8
    ISSN 1476-5594 ; 0950-9232
    ISSN (online) 1476-5594
    ISSN 0950-9232
    DOI 10.1038/sj.onc.1201546
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 2218: Show issues Location:
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  3. Article: Expression of alternatively spliced PCTAIRE-1 mRNA in PC12 cells and neonatal rat brain.

    Gao, C Y / Chauthaiwale, V M / Rampalli, A M / Zelenka, P S

    Gene

    1996  Volume 176, Issue 1-2, Page(s) 243–247

    Abstract: A rat PCTAIRE-1 cDNA clone was isolated by immunoscreening of a PC12 cDNA library, followed by 5' RACE (rapid amplification of cDNA ends) to determine the 5' end. The rat PCTAIRE-1 cDNA sequence is 96% identical to mouse PCTAIRE-1 and contains an ... ...

    Abstract A rat PCTAIRE-1 cDNA clone was isolated by immunoscreening of a PC12 cDNA library, followed by 5' RACE (rapid amplification of cDNA ends) to determine the 5' end. The rat PCTAIRE-1 cDNA sequence is 96% identical to mouse PCTAIRE-1 and contains an alternatively spliced exon of 131 bp near the 5' end. Although a mouse cDNA containing this exon has been reported, examination of several mouse cell lines provided no evidence for expression of the corresponding mRNA (Okuda et al., 1992). In contrast, reverse transcription and polymerase chain reaction (RT/PCR) across this region using RNA from proliferating, differentiated, and apoptotic PC12 cells demonstrated that alternatively spliced forms of PCTAIRE-1 mRNA with and without this exon are expressed. Both forms of PCTAIRE-1 mRNA are also expressed in vivo in neonatal rat brain, although other tissues examined contained only the form lacking the alternatively spliced exon. In the absence of the alternatively spliced exon PCTAIRE-1 mRNA contains an open reading frame of 1488 bp, corresponding to a 55-kDa protein that is 97% identical to mouse PCTAIRE-1 protein. When the alternatively spliced exon is present, this open reading frame is terminated by a stop codon and a second open reading frame is initiated, predicting a second PCTAIRE-1 protein of 52 kDa. The two predicted PCTAIRE-1 proteins are identical downstream of the splice site, but share no homology at their N-terminal ends.
    MeSH term(s) Alternative Splicing ; Amino Acid Sequence ; Animals ; Animals, Newborn ; Base Sequence ; Cloning, Molecular ; Cyclin-Dependent Kinases ; DNA, Complementary ; Gene Expression ; Humans ; Molecular Sequence Data ; PC12 Cells ; Protein Biosynthesis ; Protein-Serine-Threonine Kinases/genetics ; RNA, Messenger ; Rats ; Sequence Analysis, DNA
    Chemical Substances DNA, Complementary ; RNA, Messenger ; Protein-Serine-Threonine Kinases (EC 2.7.11.1) ; Cyclin-Dependent Kinases (EC 2.7.11.22) ; PCTAIRE-1 protein kinase (EC 2.7.11.22)
    Language English
    Publishing date 1996-10-17
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 391792-7
    ISSN 1879-0038 ; 0378-1119
    ISSN (online) 1879-0038
    ISSN 0378-1119
    DOI 10.1016/0378-1119(96)83274-4
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 1357: Show issues Location:
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  4. Article: Changes in cyclin dependent kinase expression and activity accompanying lens fiber cell differentiation.

    Gao, C Y / Rampalli, A M / Cai, H C / He, H Y / Zelenka, P S

    Experimental eye research

    1999  Volume 69, Issue 6, Page(s) 695–703

    Abstract: Previous studies from this laboratory have shown that differentiating lens fiber cells contain two active cyclin dependent kinases (Cdks), Cdk1 and Cdk5. The present study was undertaken to explore the expression and regulation of six additional members ... ...

    Abstract Previous studies from this laboratory have shown that differentiating lens fiber cells contain two active cyclin dependent kinases (Cdks), Cdk1 and Cdk5. The present study was undertaken to explore the expression and regulation of six additional members of the Cdk family (Cdk2, Cdk3, Cdk4, Cdk6, Cdk7 and Cdk8) during lens differentiation. Differentiating lens fiber cells were separated from lens epithelial cells by microdissection of developing rat lenses [embryonic day 16 (E16) to postnatal day 8 (P8)] and Cdk expression was assessed by RT-PCR and immunoblotting. Two Cdks (Cdk3 and Cdk6) were not expressed in lens fiber cells or epithelial cells during this developmental period. In the lens epithelium, we detected proteins and mRNAs corresponding to all other Cdks examined (Cdk2, Cdk4, Cdk7, Cdk8) throughout this developmental period. Epithelial cells showed significant Cdk2 activity, which decreased with developmental age, but no significant activity was detected for Cdk4, Cdk7, or Cdk8. Fiber cells contained all four Cdk proteins and the corresponding Cdk mRNAs except for Cdk2 mRNA. None of the Cdks examined showed significant kinase activity in fiber cells. Immunoprecipitates of Cdk2 and Cdk4 from fiber cells contained p57(kip2), supporting the view that this Cdk inhibitor blocks the activity of these Cdks in lens fibers. In contrast, p57(kip2)did not co-immunoprecipitate with Cdk5 from lens fibers. These findings suggest that the differential affinity of p57(kip2)for members of the Cdk family may provide a mechanism for specific regulation of individual Cdks during fiber cell differentiation.
    MeSH term(s) Animals ; CDC2-CDC28 Kinases ; Cyclin-Dependent Kinase 2 ; Cyclin-Dependent Kinase 4 ; Cyclin-Dependent Kinases/genetics ; Cyclin-Dependent Kinases/metabolism ; DNA Primers ; Electrophoresis, Polyacrylamide Gel ; Embryonic Induction ; Epithelial Cells/metabolism ; Gene Expression ; Immunoblotting ; Lens, Crystalline/cytology ; Lens, Crystalline/embryology ; Lens, Crystalline/metabolism ; Precipitin Tests ; Protein-Serine-Threonine Kinases/genetics ; Protein-Serine-Threonine Kinases/metabolism ; Proto-Oncogene Proteins ; Rats ; Rats, Wistar ; Reverse Transcriptase Polymerase Chain Reaction
    Chemical Substances DNA Primers ; Proto-Oncogene Proteins ; Protein-Serine-Threonine Kinases (EC 2.7.11.1) ; CDC2-CDC28 Kinases (EC 2.7.11.22) ; Cdk2 protein, rat (EC 2.7.11.22) ; Cdk4 protein, rat (EC 2.7.11.22) ; Cyclin-Dependent Kinase 2 (EC 2.7.11.22) ; Cyclin-Dependent Kinase 4 (EC 2.7.11.22) ; Cyclin-Dependent Kinases (EC 2.7.11.22) ; cyclin-dependent kinase-activating kinase (EC 2.7.11.22)
    Language English
    Publishing date 1999-12
    Publishing country England
    Document type Journal Article
    ZDB-ID 80122-7
    ISSN 1096-0007 ; 0014-4835
    ISSN (online) 1096-0007
    ISSN 0014-4835
    DOI 10.1006/exer.1999.0749
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 163: Show issues Location:
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