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Biomedical subjects

H Alder

Publications and source records attributed to H Alder.

At least 19 recordsLinked to original sources
PubMed1995

A novel t(9;11)(p22;q23) with ALL-1 gene rearrangement associated with progression of a myeloproliferative disorder to acute myeloid leukemia.

We have analyzed genomic DNAs from a patient who developed acute myeloid leukemia 1 year after a myeloproliferative disorder was diagnosed. The development of the acute leukemia was associated with the acquisition of a t(9;11)(p22;q23) chromosome translocation. ALL-1 gene rearrangement, on chromosome 11, was present at the onset of the acute phase, but not during the chronic phase of the myeloproliferative disorder. The genomic rearrangement on chromosome 9 was within an unidentified region. By the use of polymerase chain reaction, we were able to determine that the chromosomal rearrangement was completely absent during the chronic phase of the myeloproliferative disorder, indicating that the ALL-1 gene rearrangement was causally related to the development of the acute phase. The rapid progression into the acute phase suggests that this case might be therapy related. This work provides a clear example of association of a molecular defect with the development of a specific clinical leukemic stage, and supports the indication that ALL-1 gene rearrangement is associated with poor clinical outcome in adult leukemias.

Adult↗
PubMed1995

Junctional region of the myelin basic protein-specific T cell receptor beta chain in mice.

Evidence for the existence of both conserved and diverse amino acid sequences in the junctional regions of the myelin basic protein (MBP)-specific T cell receptors (TCR) in mice is presented. The junctional region of the Nac1-11 MBP peptide-specific, H-2u-restricted TCR beta-chains is characterized by the utilization of similar amino acid sequences. In contrast, diverse junctional sequences within the TCR beta-chains of the p89-101 MBP peptide and H-2s-restricted T cell clones are reported. These findings demonstrate that a limited heterogeneity of the MBP-specific T cell clones does exist. However, it may not be universal even in inbred mouse strains.

Amino Acid Sequence↗
PubMed1995

Characteristics of the T lymphocytes involved in experimental allergic encephalomyelitis.

Both heterogeneity and restricted heterogeneity of the encephalitogenic myelin basic protein (MBP) peptide-specific T cell receptors (TCRs) were demonstrated in inbred animals depending on the strain-specific genetic characteristics, the stage of the disease, the compartment of the lymphocytes obtained and the methodology used. Nevertheless, the similar features of some MBP-specific TCRs demonstrated across species suggest that conservation of these autoantigen-specific molecules undoubtedly exists, even though the degree of this conservation is controversial. However, the unequivocal heterogeneity of the immune response directed at one of the most important myelin constituents, proteolipid lipoprotein (PLP), which occurs either as a primary or a secondary event during experimental allergic encephalomyelitis (EAE), indicates the complexity of the in vivo situation. Intramolecular and intermolecular spreading of antigen specificity during the course of the disease indicates that a TCR directed therapy may not be the choice of intervention in established disease even in individual strains of laboratory animals with restricted heterogeneity of the primary MBP-specific response. Studying the sequence of events, the recruited regulatory cells and cytokines, and the stromal factors controlling persistence or death of activated, memory cells in the tissue lesion, may reveal new therapeutic modalities with more universal applicabilities.

Animals↗
PubMed1992

The t(4;11) chromosome translocation of human acute leukemias fuses the ALL-1 gene, related to Drosophila trithorax, to the AF-4 gene.

The ALL-1 gene located at human chromosome 11 band q23 is rearranged in acute leukemias with interstitial deletions or reciprocal translocations between this region and chromosomes 1, 4, 6, 9, 10, or 19. The gene spans approximately 100 kb of DNA and contains at least 21 exons. It encodes a protein of more than 3910 amino acids containing three regions with homology to sequences within the Drosophila trithorax gene, including cysteine-rich regions that can be folded into six zinc finger-like domains. The breakpoint cluster region within ALL-1 spans 8 kb and encompasses several small exons, most of which begin in the same phase of the open reading frame. The t(4;11) chromosome translocation results in two reciprocal fusion products coding for chimeric proteins derived from ALL-1 and from a gene on chromosome 4. This suggests that each 11q23 abnormality gives rise to a specific oncogenic fusion protein.

Amino Acid Sequence↗
PubMed1992

The (4;11)(q21;q23) chromosome translocations in acute leukemias involve the VDJ recombinase.

Chromosomal region 11q23 is frequently rearranged in acute lymphocytic leukemias (ALLs) and in acute myeloid leukemias (AMLs), mostly in reciprocal exchanges with various translocation partners. The most common of these translocations is t(4;11)(q21;q23). It is present in approximately 10% of ALL patients, most frequently in very young children. We have recently cloned a region of chromosome 11, the ALL-1 locus, found to be rearranged in malignant cells from patients with the t(4;11), t(9;11), t(11;19), t(1;11), t(6;11), t(10;11), and del(11q23) chromosomal abnormalities. Here we report the cloning and characterization of chromosomal breakpoints from leukemic cells with t(4;11) aberrations. The breakpoints cluster in regions of 7-8 kilobases on both chromosomes 4 and 11. The presence of heptamer- and nonamer-like sequences at the sites of breakage suggests that the VDJ recombinase utilized for immunoglobulin gene rearrangement is also directly involved in these translocations. We also show that leukemic cells with t(4;11) express altered RNAs transcribed from the derivative chromosomes 11 and 4.

Acute Disease↗
PubMed1992

Inhibition of cell cycle progression by antisense oligodeoxynucleotides.

We have used the antisense strategy to study the role of certain genes in cell cycle progression. In particular, we used antisense oligodeoxynucleotides to study: (1) the role of the IGF-1 receptor in the control of cell proliferation; and (2) the sequence of gene expression during the cell cycle. Our results can be summarized as follows: (1) the activation of the IGF-1 receptor by its ligand, IGF-1, is an obligatory step in the proliferation of fibroblasts and hemopoietic cells; and (2) the expression of DNA synthesis genes, such as PCNA, DNA polymerase alpha, and cdc2, is dependent on the expression of previous genes. A tentative temporal order is: c-myc > c-myb > IGF-1 receptor > DNA synthesis genes.

Animals↗
PubMed1992

Cell cycle effects of microinjected antisense oligodeoxynucleotides to p34cdc2 kinase.

In this study the effect of antisense oligomers targeted against the mRNA transcripts of p34cdc2 kinase on G1 progression into S-phase was examined. For this purpose, antisense, sense, or nonsense oligomers were introduced directly into the cytoplasm of T98G cells grown in monolayer cultures by glass-capillary microinjection. The microinjection of antisense oligomers (but not sense or nonsense oligomers) into growth-arrested cells before serum stimulation inhibited G1 progression into S-phase. This inhibition was correlated with a reduction in the steady-state levels of nuclear p34cdc2 protein. Microinjection of antisense oligomers into cells at 2 and 6 hours after serum stimulation also resulted in a marked inhibition in the ability of cells to enter S-phase. The inhibitory effect decreased when cells were microinjected at 12 hours after serum stimulation. When cells were microinjected at 18 and 24 hours after serum stimulation, only a slight inhibition was observed. As the antisense oligomers were introduced directly into the cytoplasm of cells at each of the time points examined, the observed differences in the inhibitory effects of the antisense oligomers at later times after serum stimulation cannot be explained by differences in uptake. An alternative explanation is that after a certain threshold level of nuclear p34cdc2 protein is reached in late G1 phase; no further increase is necessary, because the cells become committed to enter S-phase. In yeast, p34cdc2 appears to play an important role in the G1/S-phase transition at a control point in late G1 phase called START (reviewed by Lewin). In mammalian cells a control point that could be equivalent to START is the "restriction point" which is defined as the time after which inhibition of protein synthesis fails to block entry into S-phase (reviewed by Pardee). The effects observed with antisense oligomers to p34cdc2 kinase are strikingly similar to what is observed when low concentrations of the drug cycloheximide are added to these cells at different times after serum stimulation; entry into S-phase is significantly inhibited when cycloheximide is added up to 12 hours postimulation. Thus, the results reported in this study are in agreement with the idea that p34cdc2 kinase plays a role in the G1/S phase transition in mammalian cells. Finally, introduction of antisense oligomers directly into the cytoplasm of cells grown in monolayer cultures by glass-capillary microinjection appears to be a viable alternative to simply adding the oligomers to the culture medium.(ABSTRACT TRUNCATED AT 400 WORDS)

Base Sequence↗
PubMed1992

A conserved region in intron 1 negatively regulates the expression of the PCNA gene.

The Proliferating Cell Nuclear Antigen (PCNA) gene is a growth-regulated gene, whose expression is under the control of both transcriptional and posttranscriptional mechanisms. In previous work, it was shown that the 73 bp immediately upstream of the CAP site and intron 4 are major regulatory elements. We show here that intron 1 also plays a role in determining the levels of PCNA mRNA. Specifically, we show: 1) deletion of intron 1 increases the expression of PCNA mRNA in serum-deprived cells; 2) a 35 bp sequence in intron 1, containing a reverse CCAAT element specifically binds proteins from nuclear extracts; 3) this intron 1 sequence inhibits the expression of a co-tranfected human PCNA gene in transient expression assays suggesting that it competes for positive transcription factors; 4) mutations in the CCAAT region of the 35bp intron 1 probe abrogate both its protein-binding capacity and its ability to inhibit the expression of a co-transfected wt PCNA gene; and 5) the CCAAT region of human intron 1 is highly conserved in the mouse gene. We conclude that the reverse CCAAT region of intron 1 is a negative regulatory element of PCNA gene expression, and hypothesize that its inhibitory effect is abolished when certain protein(s) bind to it and that inhibition is restored if these proteins are competed out by an homologous sequence.

Antigens, Neoplasm↗
PubMed1992

The role of the promoter in the expression of the PCNA gene.

G1-specific temperature-sensitive (ts) mutants of the cell cycle arrest in G1 after serum stimulation at the restrictive temperature. Under these conditions, the RNA levels of late growth-regulated genes (such as DNA polymerase alpha, PCNA, thymidine kinase, and core histones) are markedly decreased or even undetectable, while early growth-regulated genes (for instance, c-myc) are normally expressed, and certain promoters are actually super-induced. We have used the human PCNA gene transfected into TK-ts13 cells (a G1-specific ts mutant) to investigate whether the inhibition of gene expression caused by this type of growth inhibition occurs at a transcriptional or post-transcriptional level. Constructs were made in which the 5' and 3' flanking sequences of the human PCNA gene were replaced by the corresponding elements of the SV40 T antigen coding gene. Using these constructs and data from run-on assays and RT-PCR, we conclude that the failure of expression of the PCNA gene in G1-arrested TK-ts13 cells occurs at the transcriptional level.

Animals↗
PubMed1991

Characterization of an enhancer-like structure in the promoter region of the proliferating cell nuclear antigen (PCNA) gene.

The steady-state mRNA levels of the proliferating cell nuclear antigen (PCNA) gene depend on the length of its promoter. A promoter extending from the HpaII restriction site at -210 from the cap site to the cap site itself is very active, while a -45 promoter (AatII restriction site) is very weak. We now show that the sequences between -73 and -45 of the human PCNA promoter contain an enhancer-like sequence that markedly increases the levels of PCNA mRNA. This sequence has characteristics of an enhancer, having an enhancing function also when placed away from the native position in the 5' flanking sequence. The increase in mRNA levels that occurs after serum stimulation, however, is independent of the enhancer. Synthetic promoters were also constructed containing mutations in the -73 to -45 sequence and these mutants completely lost their ability to drive the transcription of a heterologous cDNA. Nuclear proteins were shown to bind to this sequence, both by gel shift and by methylation interference analysis. We conclude that the levels of PCNA mRNA are controlled, in part, by a structure located in the 5' flanking sequence of the gene, but that this enhancer-like structure does not play a role in the serum regulation of the mRNA levels.

Animals↗
PubMed1991

A new growth-regulated complementary DNA with the sequence of a putative trans-activating factor.

A new complementary DNA (cDNA) clone has been isolated by differential screening of a cDNA library. The cognate RNA of this clone, called SC1, is growth regulated in human, mouse, and hamster cell lines. Its kinetics of growth regulation (time of increase in mRNA levels, sensitivity to cycloheximide, behavior in G1-specific temperature-sensitive mutants) classify the SC1 gene as a late growth-regulated gene, like the histone genes and the genes coding for the proteins of the DNA synthesis apparatus. By run-on assay, there is a modest increase in transcriptional rates after serum stimulation, which is not sufficient to explain the sharp increase in mRNA levels. The SC1 gene localizes to human chromosome 6p21-22. In bacteria, the SC1 cDNA clone makes a protein of Mr 39,000, in agreement with the putative reading frame. The amino acid sequence derived from the cDNA sequence indicates a previously unknown gene with a domain strongly suggestive of a trans-activating domain. The SC1 gene can be considered as coding for a possible new trans-activating factor that could play an important role in the transcription of genes required for the later stages of cell cycle progression.

Amino Acid Sequence↗
PubMed1989

Temporary complementation of temperature-sensitive mutants of the cell cycle by transfection with a wild-type or a mutant cDNA of ADP/ATP translocase.

A number of cell-cycle-specific temperature-sensitive (ts) mutants have been isolated from animal cells, especially Syrian hamster cells. These ts mutants, like cell cycle ts mutants of yeast, can be complemented by specific genes, some of which have been molecularly cloned. We have isolated a cDNA clone that complements TK-ts13 cells, but only temporarily. This clone, called B1, differs from a previously isolated clone (Sekiguchi et al.: EMBO Journal 7:1683-1687, 1988) that specifically complements ts13 cells. In addition, B1 also complemented temporarily three other ts mutants of the cell cycle, tsAF8, ts694, and ts550C cells. These mutants have different mutations since, in cell fusion experiments, they complement each other. Sequencing of the B1 cDNA clone revealed that it was a mutant of human ADP/ATP translocase in which some human sequences at the 5' end have been replaced by SV40 sequences. The wild-type translocase was less effective but could still increase the survival time of cell cycle ts mutants at the restrictive temperature. Using the polymerase chain reaction, it was possible to demonstrate that the B1 plasmid is expressed in TK-ts13 cells undergoing temporary complementation.

Amino Acid Sequence↗
PubMed1988

Transdifferentiation from striated muscle of medusae in vitro.

We have established an in vitro transdifferentiation and regeneration system which is based entirely on mononucleated striated muscle cells. The muscle tissue is isolated from anthomedusae and activated by various means to undergo cell cycles and transdifferentiation to several new cell types. In all cases DNA-replication is initiated and the division products are smooth muscle cells, characterized by their ultrastructure and monoclonal antibodies, and nerve/sensory cells, characterized by their ultrastructure and FMRFamide-staining. Both cell types are found at a 1:1 ratio after the first division. The nerve cells stop to replicate, whereas the smooth muscle cells continue and keep producing in each successive division a smooth muscle cell and a nerve cell. The observed data indicate that smooth muscle cells behave like stem cells. Depending on the destabilization and culturing methods, some isolated muscle tissue will form a bilayered fragment and within only two cell cycles manubria (the feeding and sexual organ) or tentacles will regenerate. In this case six to eight new non-muscle cell types have been formed by transdifferentiation.

Animals↗
PubMed1987

Cell cycles and in vitro transdifferentiation and regeneration of isolated, striated muscle of jellyfish.

Isolated, mononucleated, cross-striated muscle cells of a medusa can transdifferentiate in vitro to various new cell types and even form a complex regenerate. The transdifferentiation events follow a strict pattern. The first new cell type resembles smooth muscle and is formed without a preceding DNA replication. This cell type behaves like a stem cell and by quantal cell cycles produces all other new cell types. Some preparations develop an inner and an outer layer separated by a basal lamella. Formation of these layers does not depend on DNA replication. When layers do not form, each division results in nerve cells and smooth muscle cells. If separation into layers occurs, then a regenerate will be formed, and in the course of only two cell cycles all necessary cell types to form a functional regenerate will differentiate.

Animals↗
PubMed1987

In vitro transdifferentiation of striated muscle to smooth muscle cells of a medusa.

Mononucleated striated muscle cells can be isolated from anthomedusae and cultivated in artificial seawater. In the cultivated muscle the differentiated state is maintained and DNA synthesis is not observed. The isolated striated muscle can be activated by collagenase treatment to transdifferentiate into various new cell types. Between the second and third day following collagenase treatment DNA synthesis is initiated, and mitosis and de novo flagellum formation occur in the isolated muscle. Under these circumstances all isolated striated muscle fragments produce both smooth muscle cells and y-cells (Schmid and Alder, 1984). In experiments, in which either transcription (actinomycin D) or translation (cycloheximide) is inhibited, the activated striated muscle cells do not transdifferentiate but maintain their differentiated state. Inhibition of DNA replication (aphidicolin), however, results in uniform transdifferentiation of striated muscle to smooth muscle cells in the absence of y-cell types (Schmid and Alder, 1984). The fluorescence stain NBD-phallacidin is used to monitor the characteristic change of F-actin pattern of these isolates.

Actins↗