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D L Rimm

Publications and source records attributed to D L Rimm.

At least 55 records · Page 3Linked to original sources
PubMed1996

Expression of a candidate cadherin in T lymphocytes.

Cadherins are homotypic adhesion molecules that classically mediate interactions between cells of the same type in solid tissues. In addition, E-cadherin is able to support homotypic adhesion of epidermal Langerhans cells to keratinocytes (Tang, A., Amagai, M., Granger, L. G., Stanley, J. R. & Udey, M. C. (1993) Nature (London) 361, 82-85) and heterotypic adhesion of mucosal epithelial cells to E-cadherin-negative intestinal intraepithelial T lymphocytes. Thus, we hypothesized that cadherins may play a wider role in cell-to-cell adhesion events involving T lymphocytes. We searched for a cadherin or cadherins in T lymphocytes with a pan-cadherin antiserum and antisera against alpha- or beta-catenin, molecules known to associate with the cytoplasmic domain of cadherins. The anti-beta-catenin antisera coimmunoprecipitated a radiolabeled species in T-lymphocyte lines that had a molecular mass of 129 kDa and was specifically immunoblotted with the pan-cadherin antiserum. Also, the pan-cadherin antiserum directly immunoprecipitated a 129-kDa radiolabeled species from an 125I surface-labeled Jurkat human T-cell leukemic cell line. After V8 protease digestion, the peptide map of this pan-cadherin-immunoprecipitated, 129-kDa species exactly matched that of the 129-kDa species coimmunoprecipitated with the beta-catenin antiserum. These results demonstrate that T lymphocytes express a catenin-associated protein that appears to be a member of the cadherin superfamily and may contribute to T cell-mediated immune surveillance.

Animals↗
PubMed1996

Atypical reparative change on cervical/vaginal smears may be associated with dysplasia.

The Bethesda System for classifying cervical/vaginal smears has divided reparative changes into two categories: typical and atypical. Although atypical repair may be grouped with atypical squamous cells of unknown significance (ASCUS), this study selected cases specifically diagnosed as atypical reparative changes (ARC), which showed streaming sheets of cells and enlarged nuclei with nucleoli and anisonucleosis. Our goal was to determine the validity of grouping atypical repair with ASCUS. All cases were received by the Medical College of Virginia-Virginia Commonwealth University (MCV-VCU) pathology department in a 6-month period in 1993. Of 196 cases, 55 (28%) were biopsied within a subsequent 3-6-month period. Of these, 27 also carried a diagnosis of ASCUS (9), low-grade squamous intraepithelial lesion (LGSIL) (15), or high-grade squamous intraepithelial lesion (HGSIL) (3). The remaining 28 were presumably biopsied on the basis of clinical concern regarding a diagnosis of ARC. This group, which represents only 14% of the total with the ARC diagnosis, showed a spectrum of histologic changes from squamous metaplasia and chronic cervicitis to HGSIL. Surprisingly, 25% of these patients (7 of 28) showed changes of LGSIL or higher, including 2 (7%) showing HGSIL. This level of higher grade histologic findings justifies separation of atypical from typical repair. Although there are some cases with a significant histologic abnormality found with a cytologic diagnosis of ARC, the percentage of cases is not nearly as high as the 60% range seen associated with the diagnosis of ASCUS. Due to the lack of consensus on the clinical management of ASCUS, we find no justification to separate the diagnosis of ARC from that of ASCUS.

Biopsy↗
PubMed1995

Alpha 1(E)-catenin is an actin-binding and -bundling protein mediating the attachment of F-actin to the membrane adhesion complex.

Calcium-dependent homotypic cell-cell adhesion, mediated by molecules such as E-cadherin, guides the establishment of classical epithelial cell polarity and contributes to the control of migration, growth, and differentiation. These actions involve additional proteins, including alpha- and beta-catenin (or plakoglobin) and p120, as well as linkage to the cortical actin cytoskeleton. The molecular basis for these interactions and their hierarchy of interaction remain controversial. We demonstrate a direct interaction between F-actin and alpha (E)-catenin, an activity not shared by either the cytoplasmic domain of E-cadherin or beta-catenin. Sedimentation assays and direct visualization by transmission electron microscopy reveal that alpha 1(E)-catenin binds and bundles F-actin in vitro with micromolar affinity at a catenin/G-actin monomer ratio of approximately 1:7 (mol/mol). Recombinant human beta-catenin can simultaneously bind to the alpha-catenin/actin complex but does not bind actin directly. Recombinant fragments encompassing the amino-terminal 228 residues of alpha 1(E)-catenin or the carboxyl-terminal 447 residues individually bind actin in cosedimentation assays with reduced affinity compared with the full-length protein, and neither fragment bundles actin. Except for similarities to vinculin, neither region contains sequences homologous to established actin-binding proteins. Collectively these data indicate that alpha 1 (E)-catenin is a novel actin-binding and -bundling protein and support a model in which alpha 1(E)-catenin is responsible for organizing and tethering actin filaments at the zones of E-cadherin-mediated cell-cell contact.

Actins↗
PubMed1995

Autoantibodies specific for villin found in patients with colon cancer and other colitides.

We have sought evidence for blood-borne autoantigens from the apical regions of the intestinal epithelial cell that are associated with specific gastrointestinal diseases. While a wide range of brush border-specific proteins are antigenic in various disease states, significantly increased levels of autoantibody to villin, a 95-kDa protein microvillar actin-binding protein, were identified by western blot in colon cancer patients' sera. Examination of a population with a range of colonic diseases showed that anti-villin antibody is most prevalent in patients with colon cancer at significantly higher (P < 0.005) levels than normal controls. We conclude that cryptic antigens within the brush border, specifically including villin, incite an active autoimmune response. The pathological significance of these antibodies remains to be determined. These anti-villin antibodies also may provide a unique noninvasive approach for the detection of gastrointestinal pathology.

Acute Disease↗
PubMed1995

Receptor protein tyrosine phosphatase PTPmu associates with cadherins and catenins in vivo.

The extracellular segment of the receptor-type type protein tyrosine phosphatase PTPmu, possesses an MAM domain, an immunoglobulin domain, and four fibronectin type-III repeats. It binds homophilically, i.e., PTPmu on the surface of one cell binds to PTPmu on an apposing cell, and the binding site lies within the immunoglobulin domain. The intracellular segment of PTPmu has two PTP domains and a juxtamembrane segment that is homologous to the conserved intracellular domain of the cadherins. In cadherins, this segment interacts with proteins termed catenins to mediate association with the actin cytoskeleton. In this article, we demonstrate that PTPmu associates with a complex containing cadherins, alpha- and beta-catenin in mink lung (MvLu) cells, and in rat heart, lung, and brain tissues. Greater than 80% of the cadherin in the cell is cleared from Triton X-100 lysates of MvLu cells after immunoprecipitation with antibodies to PTPmu; however, the complex is dissociated when lysates are prepared in more stringent, SDS-containing RIPA buffer. In vitro binding studies demonstrated that the intracellular segment of PTPmu binds directly to the intracellular domain of E-cadherin, but not to alpha- or beta-catenin. Consistent with their ability to interact in vivo, PTPmu, cadherins, and catenins all localized to points of cell-cell contact in MvLu cells, as assessed by immunocytochemical staining. After pervanadate treatment of MvLu cells, which inhibits cellular tyrosine phosphatase activity including PTPmu, the cadherins associated with PTPmu are now found in a tyrosine-phosphorylated form, indicating that the cadherins may be an endogenous substrate for PTPmu. These data suggest that PTPmu may be one of the enzymes that regulates the dynamic tyrosine phosphorylation, and thus function, of the cadherin/catenin complex in vivo.

Animals↗
PubMed1995

Reduced alpha-catenin and E-cadherin expression in breast cancer.

BACKGROUND: The expression of the homotypic cell adhesion protein, E-cadherin, is reduced in many types of cancer. The loss of this protein may be associated with metastasis because alteration of its function is required for invasion in vitro, and decreased expression has been associated with more aggressive tumor behavior in vivo. It is likely that the loss of downstream effector elements in the cadherin adhesion cascade may also disrupt cell-cell interactions and thereby promote invasion, but direct evidence for this has been lacking. One such effector element is alpha-catenin, a cytoplasmic protein related to vinculin that is associated in vivo with E-cadherin. EXPERIMENTAL DESIGN: In the present study, antibodies prepared to recombinant human alpha-catenin and recombinant human E-cadherin have been used to explore by immunocytochemistry the steady state levels of these proteins in a series of 26 cancers of the breast. RESULTS: The expression of alpha-catenin was reduced or lost more frequently (81% of cases) than was the expression of E-cadherin (63% of cases). Cases with absent E-cadherin expression uniformly lacked alpha-catenin. Eight of the 26 patients (31%) had known metastatic disease at the time of biopsy; yet, all patients with normal alpha-catenin staining in their tumors were free of known metastatic disease (four patients). CONCLUSIONS: Together with previous data on E-cadherin, these results suggest that reduced steady state levels of alpha-catenin may be a sensitive marker for disturbances in the adhesive function of the junctional complex and suggest that failure of at least one component of the cadherin-mediated cell-cell adhesion cascade is a common feature of breast, and presumably other, epithelial tumors.

Adult↗
PubMed1994

Adhesion between epithelial cells and T lymphocytes mediated by E-cadherin and the alpha E beta 7 integrin.

In contrast to sessile cell types, lymphocytes migrate through the vasculature to become diffusely distributed in tissues or organized in lymphoid structures. A complex array of adhesion molecules including selectins, integrins and their counter-receptors mediate lymphocyte homing and migration into tissues and may be constitutively expressed or induced. However, the molecules that mediate the tissue-specific retention of lymphocytes within the parenchyma have not been identified. Along the epithelium at the basolateral surface of enterocytes, intestinal intraepithelial lymphocytes are found. These T cells of the mucosal immune system serve as a model for the tissue-specific compartmentalization of lymphocytes. We investigated whether the localization of these intestinal intraepithelial lymphocytes could be mediated by specific interactions between adhesion molecules expressed selectively on this subpopulation of T cells and tissue-restricted adhesion molecules on epithelial cells. Here we show that heterotypic adhesive interactions between epithelial cells and intraepithelial lymphocytes in vitro are mediated by E-cadherin and the alpha E beta 7 integrin.

Animals↗
PubMed1994

Molecular cloning reveals alternative splice forms of human alpha(E)-catenin.

At least three proteins (alpha, beta, and gamma catenin) comprise the cytoplasmic domain of the cadherin cell-cell adhesion complex. We have cloned and sequenced human epithelial alpha(E)-catenin and have identified two distinct transcripts, designated alpha 1- and alpha 2-. The human alpha 1(E)-catenin transcript predicts a 907 aa sequence 97% identical to mouse alpha-catenin. The second transcript, alpha 2(E)-catenin, displays a 24 amino acid insertion after codon 812, yielding a 931 amino acid protein (GenBank #L23805). Analysis by RT-PCR and Northern blotting detects one or both transcripts in epithelial and non-epithelial tissues. Southern blotting indicates that both arise from a single gene. The alternative transcription site in alpha-catenin is analogous to the splice site in vinculin that creates met alpha-vinculin, extending the homology between alpha-catenin and vinculin. These data with the reported structure of other catenin genes suggest that vinculin and alpha-catenin generate a superfamily of proteins mediating membrane-cytoskeletal associations.

Alternative Splicing↗
PubMed1994

Molecular cloning of human E-cadherin suggests a novel subdivision of the cadherin superfamily.

The gene encoding full-length human E-cadherin has been cloned and sequenced from liver and colon cDNA libraries (GenBank Accession #L08599). The predicted molecular mass of the unglycosylated and unprocessed protein is 97,000. The human protein conserves most features of the classical cadherins. In its cytoplasmic domain, two approximately 30-35 aminoacid conserved sequence motifs are recognized. These cadherin homology domains have been termed "CH2" and "CH3", and are characteristic of the classical cadherins, but absent or divergent in the more distantly related cadherins such as desmosomal cadherin, T-cadherin, fat, and the human ret oncogene. Given these findings and the importance of cytoplasmic interactions to cadherin function, a subclassification of the cadherin superfamily based on cytoplasmic domain homologies is proposed. This subclassification provides a framework in future studies for understanding the distinct down-stream signaling cascades associated with each cadherin.

Base Sequence↗
PubMed1991

Analysis of cDNA clones for Acanthamoeba profilin-I and profilin-II shows end to end homology with vertebrate profilins and a small family of profilin genes.

We have cloned and sequenced full length cDNAs for Acanthamoeba profilin-I and profilin-II. The genes and the encoded proteins are nearly identical except for the region between bp 121 and 210 where 35% of the nucleotides and 47% of amino acids differ. Most of these substitutions are conservative, although three of them are responsible for the differences in the isoelectric points of the isoforms [Kaiser et al., Cell Biol., 102:221-226, 1986]. The DNA sequence revealed six corrections in the previously published protein sequence of profilin-I [Ampe et al., J. Biol. Chem. 260:834-840, 1985] and for the first time resolved the ambiguities at the five positions where profilin-IA and -IB differ. The DNA sequence of profilin-II also allowed us to make two corrections in the protein sequence [Ampe et al., FEBS Lett. 228:17-21, 1988a]. Probes prepared from the cDNAs revealed 1 profilin-IA gene, one strongly cross-hybridizing profilin-I gene and one strongly reacting profilin-II gene on Southern blots of Acanthamoeba DNA. Weaker reactions with other genomic DNA fragments leave open the possibility of one additional gene each for profilin-I and profilin-II. Four different profilin RNAs were resolved on Northern blots. It possible to align the sequences of the three Acanthamoeba profilins with the sequences of nine other profilins from five different phyla. There are only two invariant residues in these profilin sequences, but many pairwise identities and conservative substitutions that indicate considerable divergence of this family of proteins from its ancestral precursor.

Acanthamoeba↗
PubMed1990

Identification of functional regions on the tail of Acanthamoeba myosin-II using recombinant fusion proteins. I. High resolution epitope mapping and characterization of monoclonal antibody binding sites.

We used a series of COOH-terminally deleted recombinant myosin molecules to map precisely the binding sites of 22 monoclonal antibodies along the tail of Acanthamoeba myosin-II. These antibodies bind to 14 distinguishable epitopes, some separated by less than 10 amino acids. The positions of the binding sites visualized by electron microscopy agree only approximately with the physical positions of these sites on the alpha-helical coiled-coil tail. On the other hand, the epitope map agrees precisely with competitive binding studies: all antibodies that share an epitope compete with each other for binding to myosin. Antibodies with adjacent epitopes can compete with each other at linear distances up to 5 or 6 nm, and many antibodies that bind 3-7-nm apart can enhance the binding of each other to myosin. Most of the antibodies that bind to the distal 37 nm of the tail disrupt assembly of octameric minifilaments and, depending upon the exact location of the binding site, stop assembly at specific steps yielding, for example, monomers, antiparallel dimers, parallel dimers or antiparallel tetramers. The effects of these antibodies on assembly identify sites on the tail that are required for individual steps in minifilament assembly. Experiments on the assembly of truncated myosin-II tails have revealed a complementary group of sites that participate in the assembly reactions (Sinard, J.H., D.L. Rimm, and T.D. Pollard. 1990. J. Cell Biol. 111:2417-2426). Antibodies that bind to the distal tail but do not affect assembly appear to have a low affinity for myosin-II. Antibodies that bind to the proximal 50 nm of the tail do not inhibit the assembly of minifilaments. Many antibodies that bind to the tail of myosin-II, even some that have no obvious effect on minifilament assembly, can inhibit the actomyosin ATPase activity and the contraction of an actin gel formed in crude extracts. An antibody that binds between amino acids 1447 and 1467 inhibits the phosphorylation of serine residues distal to residue 1483.

Acanthamoeba↗
PubMed1990

Identification of functional regions on the tail of Acanthamoeba myosin-II using recombinant fusion proteins. II. Assembly properties of tails with NH2- and COOH-terminal deletions.

We used purified fusion proteins containing parts of the Acanthamoeba myosin-II tail to localize those regions of the tail responsible for each of the three steps in the successive dimerization mechanism (Sinard, J. H., W. F. Stafford, and T. D. Pollard. 1989. J. Cell Biol. 107:1537-1547) for Acanthamoeba myosin-II minifiliment assembly. Fusion proteins containing the terminal approximately 90% of the myosin-II tail assemble normally, but deletions within the last 100 amino acids of the tail sequence alter or prevent assembly. The first step in minifilament assembly, formation of antiparallel dimers, requires the COOH-terminal approximately 30 amino acids that are thought to form a nonhelical domain at the end of the coiled-coil. The second step, formation of antiparallel tetramers, requires the last approximately 40 residues in the coiled-coil. The final step, the association of two antiparallel tetramers to form the completed octameric minifilament, requires residues approximately 40-70 from the end of the coiled-coil. A region of the tail near the junction with the heads is important for tight packing of the tails in the minifilaments. Divalent cations induce the lateral aggregation of minifilaments formed from native myosin-II or fusion proteins containing a nonmyosin "head," but under the same conditions fusion proteins composed essentially only of myosin tail sequences with very little nonmyosin sequences form paracrystals. The region of the tail necessary for this paracrystal formation lies NH2-terminal to amino acid residue 1,468 in the native myosin-II sequence.

Acanthamoeba↗
PubMed1989

New plasmid vectors for high level synthesis of eukaryotic fusion proteins in Escherichia coli.

Production of eukaryotic proteins in Escherichia coli has become rather simple since commercially available bacteriophage and plasmid vector systems allow investigators to select the optimal system for their particular problem. A common question is which system to use to produce the largest quantity of soluble recombinant protein with minimal, if any, bacterial protein fused to it. We have constructed a new set of plasmid vectors that produce large amounts of a fusion proteins that contain less than 25 amino acids of bacterial protein. We started with pATH-1, a plasmid expression vector comprised of the trpEp promoter and 37 kDa of the TrpE protein followed by a M13mp13 multiple cloning site for insertion of sequences to be expressed. We deleted the majority of the eukaryotic trpE sequence to produce a multiple frame, multiple enzyme cloning site, plasmid expression vector set called pRX. Transformation of E. coli CAG-456 (Baker et al., 1984) with this vector with an Acanthamoeba myosin tail sequence inserted in the correct frame yields a fusion protein that represents 45% of the total soluble protein. We have produced and purified 100 mg of this Acanthamoeba myosin-II fusion protein per liter of cell suspension.

Acanthamoeba↗
PubMed1989

Location of the head-tail junction of myosin.

The tails of double-headed myosin molecules consist of an alpha-helical/coiled-coil structure composed of two identical polypeptides with a heptad repeat of hydrophobic amino acids that starts immediately after a conserved proline near position 847. Both muscle and nonmuscle myosins have this heptad repeat and it has been assumed that proline 847 is physically located at the head-tail junction. We present two lines of evidence that this assumption is incorrect. First, we localized the binding sites of several monoclonal antibodies on Acanthamoeba myosin-II both physically, by electron microscopy, and chemically, with a series of truncated myosin-II peptides produced in bacteria. These data indicate that the head-tail junction is located near residue 900. Second, we compared the lengths of two truncated recombinant myosin-II tails with native myosin-II. The distances from the NH2 termini to the tips of these short tails confirms the rise per residue (0.148 nm/residue) and establishes that the 86-nm tail of myosin-II must start near residue 900. We propose that the first 53 residues of heptad repeat of Acanthamoeba myosin-II and other myosins are located in the heads and the proteolytic separation of S-1 from rod occurs within the heads.

Acanthamoeba↗
PubMed1989

Purification and characterization of an Acanthamoeba nuclear actin-binding protein.

Immunolocalization of monoclonal antibodies to Acanthamoeba myosin I showed a cross-reactive protein in nuclei (Hagen, S. J., D. P. Kiehart, D. A. Kaiser, and T. D. Pollard. 1986. J. Cell Biol. 103:2121-2128). This protein is antigenically related to myosin I in that nine monoclonal antibodies and three polyclonal antibodies are cross-reactive. However, studies with affinity-purified antibodies and two-dimensional peptide maps show that the protein is not a proteolytic product of myosin I. We have used cell fractionation and column chromatography to purify this protein. It is a dimer of 34-kD polypeptides with a Stokes' radius of 4 nm. A polyclonal antisera generated against the purified protein confirms the nuclear localization seen with the cross-reactive monoclonal antibodies. The 34-kD protein binds actin filaments in an ATP-insensitive manner with a Kd of approximately 0.25 microM without cross-linking, severing, or capping. No ATPase activity was detected in the presence or absence of actin. It also binds to DNA. These unique properties suggest we have discovered a new class of actin-binding protein. We have given this protein the name NAB for "nuclear actin-binding" protein.

Acanthamoeba↗
PubMed1989

Obesity and heredity in the etiology of non-insulin-dependent diabetes mellitus in 32,662 adult white women.

Obesity and family history of non-insulin-dependent diabetes mellitus were examined in a cross-sectional study of 32,662 white women in the United States and Canada who were members of the TOPS (Take Off Pounds Sensibly) Club, Inc., with respect to the association between these two factors and the prevalence of diabetes by using questionnaire data originally collected in 1969. A family history index based upon the reported presence of diabetes among siblings, parents, and grandparents was used to grade hereditary factors on a scale of zero to five. The ratio of actual to ideal weight was used to categorize levels of obesity. The prevalence of diabetes increased consistently with increasing levels of either obesity or family history. The two factors appear to present independent risks for diabetes. Among women with no family history of diabetes, the odds ratio for diabetes associated with a weight 75 per cent or more above ideal in comparison with a weight less than 10 per cent above ideal was 7.2. Among women who were less than 10 per cent above ideal weight for their height, a comparison between women with a family history index of 1.5 or greater and women with no family history of the disease showed an odds ratio for diabetes of 6.0. Women with both risk factors (family history index of 1.5 or greater and relative weight of 1.75 or greater) had an overall odds ratio for diabetes of 22.8 when compared with women who had no family history of diabetes and a weight less than 10 per cent above ideal. Further analysis showed the combination of these factors to have a positive synergistic effect. The interaction follows a multiplicative pattern.

Adult↗