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A Starzinski-Powitz

Publications and source records attributed to A Starzinski-Powitz.

At least 37 records · Page 2Linked to original sources
PubMed1991

Expression of M-cadherin, a member of the cadherin multigene family, correlates with differentiation of skeletal muscle cells.

Cadherins, a multigene family of transmembrane glycoproteins, mediate Ca(2+)-dependent intercellular adhesion. They are thought to be essential for the control of morphogenetic processes, including myogenesis. Here we report the identification and characterization of the cDNA of another member of the cadherin family, M-cadherin (M for muscle), from differentiating muscle cells. The longest open reading frame of the cDNAs isolated contains almost the entire coding region of the mature M-cadherin as determined by sequence homology to the known cadherins. M-cadherin mRNA is present at low levels in myoblasts and is upregulated in myotube-forming cells. In mouse L cells (fibroblasts), M-cadherin mRNA is undetectable. This expression pattern indicates that M-cadherin is part of the myogenic program and may provide a trigger for terminal muscle differentiation.

Amino Acid Sequence↗
PubMed1991

The human embryonic myosin alkali light chain gene: use of alternative promoters and 3' non-coding regions.

Recently we have found evidence that the human embryonic myosin alkali light chain (MLC1 emb) gene has two functional promoters and that its mRNAs exhibit heterogeneity in their 3'untranslated regions (UTR). To study this more in detail we have isolated and characterized the human MLC1emb gene. We focussed in particular on 2 kilobases of 5'flanking region and the alternative 3'UTRs. RNA primer extension and S1 mapping analyses revealed that the MLC1emb gene can indeed be driven either by a proximal or a distal promoter, both in fetal and adult cardiac tissue. These MLC1emb RNAs can contain either the proximal or distal 3'UTR. In contrast to this, in fetal as well as adult masseter muscle MLC1emb mRNA is predominantly transcribed from the proximal promoter and contains mainly the distal 3'UTR. These results explain the known heterogeneity of MLC1emb mRNAs. Finally, we present evidence that the murine MLC1emb gene also contains a functional distal promoter element which has hitherto been undetected.

Animals↗
PubMed1991

Formation of new muscle fibres and tumours after injection of cultured myogenic cells.

We examined the effects of implantation of cultured myogenic cells from a permanent cell line into soleus muscles of histocompatible adult mice. Myogenic cells (10(6) or 10(4)) were implanted into intact muscles, muscles frozen with liquid nitrogen, paralysed with botulinum toxin or reinnervated after long-term (seven months) denervation. Formation of numerous muscle fibres in myogenic cell-injected muscles raised the total number of fibres up to ten times above control by four weeks. Larger effects were found in freeze-damaged than in paralysed muscles. The new fibres had small calibers, considerable length (greater than 1.3 mm, maximum distance over which serial sections were made), were multinucleated and were oriented parallel to the large-diameter fibres of the host muscles. In some experiments beta-galactosidase, introduced into myogenic cells via retroviral transfection, was detected in small and large muscle fibres 4-20 weeks after implantation, indicating survival of the grafted cells and formation of mosaic (host-donor) and new fibres of donor origin. Muscle weight increased significantly and, rather surprisingly, a parallel increase was found in isometric tetanic tension of isolated nerve-muscle preparations; thus tension per mg muscle tissue was not different from normal. By eight weeks reduction of acetylcholine sensitivity and down-regulation of neural cell adhesion molecule to normal were observed, indicating that synaptic transmission at the new fibres was mature. After different periods of time (5-20 weeks, depending on the subclone used) tumours developed in most but not all injected limbs (37 out of 39). The tumours were destructive to the muscles and were classified as rhabdomyosarcomas. Prior to tumour formation, neural cell adhesion molecule positive cells reappeared in the muscles; since the myogenic cells initially produced differentiated muscle fibres, it appears that malignant growth is induced by factors in vivo. Thus, at present the outcome of such implantation is unpredictable.

Acetylcholinesterase↗
PubMed1990

Heterogenic mRNAs with an identical protein-coding region of the human embryonic myosin alkali light chain in skeletal muscle cells.

The formation of human myotubes in culture is accompanied by the induction of developmentally regulated, muscle-specific genes. We have studied the expression of human myosin light chain proteins and mRNAs during myogenesis in culture, in particular the skeletal embryonic myosin light chain 1 (MC1emb), which is indistinguishable from MLC1 of adult atrial cardiac muscle (MLC1A) as has been shown for rodent and bovine MLC1emb. We have identified distinct MLC1emb/MLC1A mRNAs in cultured human skeletal muscle cells that differ in their 5' and 3' untranslated regions but contain identical protein-coding regions. The alternative 3' untranslated region is detectable also in RNA of human atria. The different MLC1emb RNAs are likely to be encoded by one gene. It appears that the two MLC1emb 5' untranslated regions of the human gene are specific for man. In the mouse, only one 5' untranslated region of the MLC1emb gene has been detected.

Amino Acid Sequence↗
PubMed1990

Cross-reactivity of monoclonal antibody Leu-19 with some neuroectodermal and other non-immune tissues.

Leu-19 antigen is a 200-220 kDa surface glycoprotein, initially detected on natural killer (NK) cells exhibiting non-major histocompatibility complex-restricted cytotoxicity. Using a monoclonal antibody (mAb) directed against the Leu-19 molecule, we were unable to identify NK cells immunohistologically in cryostat sections of neuroectodermal tumors. Instead, mAb Leu-19 cross-reacted with the surfaces of the tumor cells, except for melanomas. It stained mesodermal tumor cells less intensely and did not stain those of carcinoma metastases. In three plasmacytomas, cells were observed, most likely NK cells, which extend Leu-19-positive cell processes towards to the unstained tumor cells. Furthermore, the Leu-19 antigen was identified on physiological tissues, especially on all neuroendocrine cells analyzed. The cross-reactions observed with Leu-19 mAb were confirmed using mAb NKH-1, which is also directed against the Leu-19 molecule. Thus, the expression of Leu-19 on neuroectodermal cells is another example of antigen sharing between specialized immune cells and the nervous system.

Adult↗
PubMed1989

Determination of RNA content in postischemic gerbil brain by in situ hybridization.

Brief periods of cerebral ischemia result in prolonged inhibition of protein synthesis. In CA1 sector of hippocampus inhibition is irreversible, leading to delayed death of pyramidal neurons. In order to study the possible role of gene transcription in this process, expression of four individual RNAs was investigated in the gerbil brain after 5 min of global cerebral ischemia by in situ hybridization with the following nucleic acid probes: plasmid pMr100 (ribosomal RNA sequences), plasma pAG82 (cytochrome c oxidase sequences), plasmid p629 (amyloid A4 precursor protein of Alzheimer's disease, pre-A4 protein), and plasmid pHF beta A-1 (beta-actin sequences). Cytochrome c oxidase mRNA and ribosomal RNA did not show any changes in expression up to 48 hr after ischemia. After longer recirculation times they gradually declined in the CA1 sector of hippocampus in parallel with the morphological manifestation of delayed neuronal death. The pre-A4 mRNA transiently decreased after 8 hr of recirculation of the CA1 sector but then recovered before it finally disappeared in parallel with delayed neuronal death. The beta-actin mRNA transiently appeared to increase after 8 hr of recirculation in the stratum radiatum of hippocampus but then also declined and disappeared when CA1 neurons began to disintegrate. The possible significance of these changes in the pathogenesis of ischemic neuronal damage is discussed.

Actins↗
PubMed1989

Lymphocyte antigen Leu-19 as a molecular marker of regeneration in human skeletal muscle.

Antigen Leu-19 (Leu19-Ag), a 200- to 220-kDa surface glycoprotein, was originally identified on a subset of human peripheral lymphocytes exhibiting non-major histocompatibility complex-restricted cytotoxicity. Here we report that monoclonal antibody Leu-19 (mAb-Leu19) labels structures in human skeletal muscle: (i) satellite cells, which form the stem cell pool of muscle fiber regeneration, both in normal and diseased muscle; (ii) myotubes and myotube projections in regions of muscle fiber repair; (iii) periodically organized fibrillar structures in areas of regeneration; (iv) the surface of myoblasts and developing myotubes in culture. mAb-Leu19 precipitated a protein of approximately 200 kDa from cultured muscle cells. Our data show that Leu19-Ag is expressed on muscle-specific components of myosegments in repair and thus represents a molecular marker of muscle regeneration. On the basis of this molecular marker and using laser scan microscopy, it is possible to visualize at the light microscopic level hitherto undetectable details of muscle regeneration in routine cryostat sections.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1989

Regulated expression of nuclear protein(s) in myogenic cells that binds to a conserved 3' untranslated region in pro alpha 1 (I) collagen cDNA.

We describe the identification and DNA-binding properties of nuclear proteins from rat L6 myoblasts which recognize an interspecies conserved 3' untranslated segment of pro alpha 1 (I) collagen cDNA. Levels of the two pro alpha 1 (I) collagen RNAs, present in L6 myoblasts, decreased drastically between 54 and 75 h after induction of myotube formation in serum-free medium. Both mRNAs contained a conserved sequence segment of 135 nucleotides (termed tame sequence) in the 3' untranslated region that had 96% homology to the human and murine pro alpha 1 (I) collagen genes. The cDNA of this tame sequence was specifically recognized by nuclear protein(s) from L6 myoblasts, as judged by gel retardation assays and DNase I footprints. The tame-binding protein(s) was able to recognize its target sequence on double-stranded DNA but bound also to the appropriate single-stranded oligonucleotide. Protein that bound to the tame sequence was undetectable in nuclear extracts of L6 myotubes that did not accumulate the two collagen mRNAs. Therefore, the activity of this nuclear protein seems to be linked to accumulation of the sequences that it recognizes in vitro. The collagen RNAs and the nuclear tame-binding proteins reappeared after a change of medium, which further suggests that the RNAs and the protein(s) are coordinately regulated.

Amino Acid Sequence↗
PubMed1988

Description of putative ribosomal RNAs with low abundance, developmental regulation, and the identifier sequence.

Three RNA species (5, 2, 0.15 kb) characterized by the repetitive identifier (ID) sequence, expressed constitutively, and at low abundance have been identified in rat L6 muscle cells by hybridization to cDNA pL6-411. Comigration of these three RNAs with 28, 18, and 5.8 S ribosomal RNAs (rRNAs) has suggested the possibility that pL6-411 RNAs are related to ribosomes or ribosome-like structures. Subsequent experiments showed that pL6-411-related RNAs could indeed be found in ribosome-like particles which were indistinguishable from ribosomes when separated on sucrose gradients under native (low salt, isolation of intact ribosomes) or denaturing conditions (detergent, high salt, isolation of ribosome subunits). Furthermore, we demonstrate that pL6-411-related RNAs are cytoplasmic in L6 cells, may be transcribed in nucleoli, and, based on their nucleotide sequence, have the potential of inter- and intramolecular hybridization. Expression of pL6-411 RNAs was also shown in adult as well as in fetal rat tissues after Day 14 of gestation. These above findings provide supportive evidence for the hypothesis that pL6-411 5- and 2-kb RNAs could exist in a subset of ribosomes. These ribosome-like pL6-411 particles nevertheless differ from ribosomes in that their associated RNAs have different nucleotide sequences, are of lower abundance, and are up-regulated later in development than rRNAs. We discuss our results in the context of a postulated ribosome subset containing RNAs other than rRNAs. These ribosome-like particles might be involved in the translational control of ID-positive mRNAs.

Animals↗
PubMed1986

Antigenic modulation of human myotube acetylcholine receptor by myasthenic sera. Serum titer determines receptor internalization rate.

Antibodies to the acetylcholine receptor (AChR) added to AChR-bearing muscle cells cross-link the receptors, thus increasing their internalization and degradation rate (antigenic modulation). This mechanism contributes to AChR loss in myasthenia gravis. Until recently, antigenic modulation has been studied in animal tissues, where only a small fraction of human anti-AChR antibodies bind. In the present study, we examined the antigenic modulation of AChR by using patients' sera and cultures of human muscle cells. We aimed to see whether antigenic modulation correlates better with disease severity or with antibody titer. Antibody-containing sera from 29 myasthenic patients in various states of the disease and with different antibody titers against AChR were tested. Control sera from six healthy individuals were also tested. Our experiments showed that all myasthenic sera affected the overall AChR content on the human myotube surface, causing a 49 to 82% loss, whereas control sera had no effect. Although at fixed serum volumes there was some correlation between disease severity and AChR loss, this effect was clearly due to differences in antibody titers. In fact, the antigenic modulation depended mainly on the final concentration of the antibody present. Thus, intrinsic factors other than antibodies to AChR may determine or influence the patients' susceptibility to the disease.

Antigens↗
PubMed1986

Decrease in acetylcholine-receptor content of human myotube cultures mediated by monoclonal antibodies to alpha, beta and gamma subunits.

One of the two main causes of acetylcholine-receptor loss in myasthenia gravis is antigenic modulation, i.e. accelerated internalization and degradation rate by antibody-crosslinking. This phenomenon has been studied only in animal tissues. Therefore, we tested antigenic modulation of the acetylcholine receptor on human embryonic myotubes in cultures. Several monoclonal antibodies to the alpha, beta and gamma subunits of the receptor reduced its concentration, in some cases down to one-third of the control. Some of these antibodies only form complexes of one antibody with two receptor molecules; consequently such small complexes are sufficient to accelerate internalization of the human acetylcholine receptor. This technique might be proved valuable for clinical screening of sera from myasthenic patients.

Animals↗
PubMed1986

Regulated expression of repetitive sequences including the identifier sequence during myotube formation in culture.

We have isolated and characterized a cDNA of 1183 bp, pL6-411, from rat L6 muscle cells. This cDNA contains repetitive sequences - including two inverted copies of the previously described identifier sequence - as shown by sequence analysis. Repetitive sequences from pL6-411 characterize a family of RNAs which is specifically induced during L6 myotube formation. Another part of the pL6-411 sequence, existing at low-copy number per haploid rat genome, hybridized to two RNAs of 5 kb and 2 kb from L6 myoblasts as well as from L6 myotubes. A third pL6-411-related RNA of 150 bases was detected which hybridized with the repetitive sequence but did not hybridize with the low-copy number part of pL6-411. It appears that the 'identifier' sequence in this population of small RNAs is complementary to one of the 'identifier' copies in the pL6-411-related RNA. Finally, we identified on cDNA pL6-411 the recognition site for the TGGCA-binding protein and in both orientations a total of four putative promoters for RNA polymerase III.

Animals↗
PubMed1982

The adenovirus type 12 - mouse cell system: permissivity and analysis of integration patterns of viral DNA in tumor cells.

The integration patterns of persisting adenovirus type 12 (Ad12) DNA were analyzed in two Ad12-induced tumors of Balb/c and CBA/J mice and in one tumor cell line derived from an Ad12-induced retinoblastoma of C3H origin. In all three tumors the Ad12 genome was integrated colinearly and various copy numbers of viral DNA were found. Analysis of the Ad12 integration patterns revealed relatively simple offsize band patterns regardless of Ad12 copy numbers. The degree of methylation at the 5'-CCGG-3' sites in the inserted Ad12 genome was determined using the isoschizomeric restriction endonuclease pair HpaII and MspI. Methylation was rather incomplete in the primary tumor tissues but almost complete in the retinoblastoma line carried in culture for many passages. The levels of expression of the viral genome in the Balb/c tumor and in the retinoblastoma line were determined by in vitro translation of RNA isolated from these cells and selected with appropriate restriction endonuclease fragments of Ad12 DNA. In both instances the 59 K, 19 K, and 17 K proteins of the E1b region were expressed. Proteins of the E1a region appeared very faint in the size class between 22 K and 42 K. The permissivity of Ad12 and the replication of Ad12 DNA in mouse cells were investigated by blotting restricted DNA from cells soon after, and a long time after, infection and by hybridization with 32P-labeled Ad12 DNA. Neither primary mouse kidney cells nor the established L929 mouse cell line supported viral DNA replication. These results raise the question to what extent host cell factors determine Ad12 DNA replication in mammalian cells.

Adenoviruses, Human↗
PubMed1978

T-cell-mediated cytotoxic immune responses to F9 teratocarcinoma cells: cytolytic effector T cells lyse H-2-negative F9 cells and syngeneic spermatogonia.

Murine thymus derived (T) lymphocytes primed in vivo to mouse 129 (H-2bc) derived H-2-negative F9 embryonal carcinoma cells and rechallenged in vitro with X-irradiated F9 stimulator cells differentiated into anti-F9 cell immune cytotoxic T lymphocytes (CTL). Using CBA mouse derived splenic responder T cells, F9 stimulator cells triggered a primary cytotoxic anti-F9 response. The CTL generated lysed the F9 antigen-positive target cells F9. PCC3 and PCC4, but not the F9 antigen-negative mouse 129 derived PYS tumor cells, nor LPS induced H-2bc blast cells. Mouse 129 anti-F9 cell antisera but not H-2k anti-H-2bc antisera blocked the lytic interaction with F9 target cells. Similarily unlabeled F9 cells but not H-2bc blast cells inhibited the anti-F9 cell cytotoxicity H-2k anti-F9 cell immune CTL were found to be cytotoxic for syngeneic spermatogonia, known to express the F9 antigen. The results suggest not only that CTL can recognize and lyse H-2-negative target cells, but also that CTL precursors can be sensitized against H-2-negative stimulator cells. From the data available it may be inferred that anti-F9 Cell immune CTL recognize the F9 antigen, known to be linked with the T/t locus. Since anti-F9 cell immune CTL lyse syngeneic spermatogonia, the system may be useful to analyze in vitro the induction and effector phase of a T-cell-mediated cytotoxic autoimmune orchitis.

Animals↗
PubMed1978

Primary in vitro sensitization of virus specific cytotoxic T lymphocytes.

CBA mouse-derived splenic lymphocytes treated with either beta-priopionlactone-inactivated or u.v. light-inactivated parainfluenza (sendai) virus stimulated in vitro unprimed syngeneic T-lymphocytes to differentiate into cytotoxic T-lymphocytes (CTL). The CTL generated were virus specific and H-2 restricted. For optimal CTL responses to be induced (i) a critical treatment of stimulator cells, (ii) an optimal ratio of responder to stimulator cells and (iii) an in vitro incubation period of 5 days was required. The in vitro system for the induction of primary virus-specific CTL responses may be useful to analyse the sensitization phase of H-2 restricted virus-specific CTL.

Animals↗