Biomedical subjects

L L Marsh

Publications and source records attributed to L L Marsh.

5 recordsLinked to original sources

PubMed1989

Spermidine labels proteins during sea urchin embryogenesis.

We have previously described the presence of a protein containing intact, covalently bound spermidine during very early embryogenesis of the sea urchin (Strongylocentrotus purpuratus). Proteins containing other polyamine metabolites also appear as embryogenesis proceeds. These proteins which contain label derived from exogenous radioactive spermidine show a characteristic pattern which changes during the course of embryonic development. We document for the first time that hypusine, the polyamine metabolite which is a characteristic component of the eukaryotic protein translation initiation factor eIF-4D, is present in more than one species of macromolecule. In addition, N1-acetylspermidine has also been identified as a significant intracellular metabolite of spermidine during embryogenesis.

Animals↗

PubMed1988

Polyamines in murine splenic lymphocytes.

Diacetyldiamines cause compromised B-lymphocyte function, as evidenced by our previous demonstration of inhibition of mitogen activation and decreased secretion of immunoglobulin in murine spleen cultures. In this study, we report that putrescine and spermidine are differentially metabolized by the cell. Diacetyldiamine, which is also taken up by these cells and metabolized, causes a striking decrease in cell uptake of exogenous putrescine and spermidine. We also report for the first time that several distinct macromolecules containing radioactive polyamines may be resolved, and that hypusine is present in more than one species of macromolecule.

Acetamides↗

PubMed1984

Polyamine metabolism in differentiating Friend erythroleukemia cells.

Changes occur in polyamine metabolism which are associated with differentiation of Friend erythroleukemia cells in culture. The intracellular distribution of the polyamines changes, the absolute level of each of the major polyamine falls, and the uptake and metabolism of exogenous putrescine is altered during the course of differentiation. We have examined the labeling of putrescine metabolites after the administration of radioactive putrescine, either as a single dose added at the onset of induction, or as a pulse label added at various times during the course of differentiation. In these experiments we measured both acid-soluble and acid-precipitable radioactivity. The conversion of putrescine to gamma-aminobutyric acid is enhanced in the cell induced to differentiate, and the acid-precipitable fraction rises as the percentage of total cell-associated radioactivity in the induced cell. We have identified hypusine [N-epsilon-(4-amino-2-hydroxybutyl)lysine] as a major radioactive component of a single radioactive Mr 18,000 protein band in both the noninduced and the induced cells.

Animals↗

PubMed1983

GABA from putrescine is bound in macromolecular form in keratinocytes.

We report for the first time that the neurotransmitter gamma-aminobutyric acid (GABA) exists in macromolecular form in keratinocytes. GABA derived from putrescine (Pu) has been identified as a component of acid-precipitable material of cultured human keratinocytes. Confluent, stratified cultures of human foreskin keratinocytes exposed to [3H]-Pu for 4 hours took up about 14% of the radioactivity from the medium and 1% of the total cell-associated radioactivity was precipitable by trichloroacetic acid (TCA). Both attached and shed cells were examined by HPLC for Pu and its radioactive metabolites in TCA-insoluble and TCA-soluble fractions. GABA accounted for the major portion (54%) of the radioactivity derived from Pu in the TCA-precipitable material of attached keratinocytes. Pu and spermidine represented lesser amounts, 35% and 9% respectively, of the total TCA-precipitable radioactivity. In addition, a large portion of acid soluble radioactivity derived from Pu (63%) was GABA, whereas Pu and spermidine represented 29% and 6% respectively of the total TCA-soluble radioactivity. The exact origin of GABA in acid-precipitable material, as well as its form of attachment, is currently under investigation.

Cell Differentiation↗

PubMedDate not supplied

Polyamines and their derivatives as modulators in growth and differentiation.

The polyamines and their derivatives are essential for life in eukaryotic and most prokaryotic cells, but their exact role in preserving cell function is not clear. These polyamines provide endogenous cations and thus participate in regulation of the intracellular pH; in addition, polyamine derivatives modulate cell growth and differentiation. The naturally occurring monoacetyl derivatives can induce increased activity of ornithine decarboxylase, the first enzyme in polyamine synthesis, and thus produce positive feedback to their production. The diacetyl derivatives of putrescine and of the synthetic analogue, 1,6-diaminohexane, induce differentiation and inhibit growth in many types of cells in vitro. In addition, they inhibit the proliferative and secretory response of normal B lymphocytes to B-cell mitogens and reduce production of antibodies in vitro. They also inhibit the proliferation of chronic lymphocytic leukemia cells (a B-lymphocyte leukemia). The parent polyamines are post-translational modifiers of proteins, and hypusine, a derivative of spermidine, is a covalently bound constituent of the eukaryotic protein synthetic initiation factor, eIF-4D. Although these various actions do not at present fall into a coherent pattern, they clearly indicate that polyamines and their derivatives play an important part in modulating cell proliferation and differentiation.

Cell Differentiation↗