Spermidine in mammalian lymphocytes and sea urchin embryos: uptake and labeling of macromolecules.

Abstract

We have studied the uptake and attachment of spermidine and some of its metabolites to cellular macromolecules in a variety of cell systems. We have selected systems which demonstrate significant uptake of polyamines when the polyamine is presented in the external environment of the cell. We chose to work with cells which are capable of increasing their metabolic activity in a manner approaching synchrony in response to a biological stimulus. In the presence of exogenous radioactive spermidine and a stimulus provoking focused cell function the cell takes up the spermidine and actively utilizes it in a biosynthetic manner. We have traced the metabolic fate of the radioactive spermidine under these conditions. The cells which we have primarily studied are young sea urchin embryos and mammalian lymphocytes. The mammalian lymphocytes we have studied include murine splenic lymphocytes, normal human peripheral lymphocytes and peripheral lymphocytes from patients with chronic lymphocytic leukemia (CLL). These represent a continuation of earlier studies where we showed that these cells can be activated by a B-cell mitogen and this activation can be abrogated by simultaneous exposure to the diacetyl derivative of putrescine or of its analogue 1, 6 diaminohexane (1–3). The sea urchin embryo studies are a continuation of earlier investigations where we documented the covalent binding of spermidine to a unique protein in very young sea urchin embryos (4). Both mitogen activation and the event of fertilization can be thought of as agents inducing “natural” synchrony and consequent increased uptake and utilization of exogenous polyamines. Certain parallels between the two biological systems as we observe them will be described. No attempt is made in this report to be inclusive in describing studies from other laboratories of polyamines associated with macromolecules. Thus, this is in the form of a progress report of our current experiments.KeywordsChronic Lymphocytic LeukemiaMurine SpleenExogenous PolyamineDiacetyl DerivativeFriend Erythroleukemia CellThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.