Role of nuclear glycogen synthase and cytoplasmic UDP glucose pyrophosphorylase in the biosynthesis of nuclear glycogen in HD33 Ehrlich-Lettré ascites tumor cells.

Abstract

Biochemical and autoradiographic evidence show both glycogen synthesis and the presence of glycogen synthase (UDP glucose [UDPG] : glycogen 4-a-D-glucosyltransf erase; EC 2.4 .1 .11) in isolated nuclei of Ehrlich-Lettre mouse ascites tumor cells of the mutant subline H D33. 5 d after tumor transplantation, glycogen (average 5-7 pg/cell) is stored mainly in the cell nuclei . The activity of glycogen synthase in isolated nuclei is 14 .5 mU/mg protein. At least half of the total cellular glycogen synthase activity is present in the nuclei . The nuclear glycogen synthase activity exists almost exclusively in its b form . The K,, value for (a + b) glycogen synthase is 1 x 10-3 M UDPG, the activation constant is 5 x 10 -3 M glucose-6-phosphate (Glc-6-P) .Light and electron microscopic autoradiographs of isolated nuclei incubated with UDP-[1-3 H]glucose show the highest activity of glycogen synthesis not only in the periphery of glycogen deposits but also in interchromatin regions unrelated to detectable glycogen particles. Together with earlier findings on nuclear glycogen synthesis in intact HD33 ascites tumor cells (Zimmermann, H .-P., V. Granzow, and C. Granzow. 1976 . J. Ultrastruct. Res. 54 :115-123), the results of tests on isolated nuclei suggest a predominantly appositional mode of nuclear glycogen deposition, without participation of the nuclear membrane system .In intact cells, synthesis of UDPG for nuclear glycogen synthesis depends on the activity of the exclusively cytoplasmic UDPG pyrophosphorylase (UTP : a-D-glucose-1-phosphate uridylyltransferase ; EC 2.7 .7 .9) . However, we conclude that glycogen synthesis is not exclusively a cytoplasmic function and that the mammalian cell nucleus is capable of synthesizing glycogen .Intranuclear glycogen deposition has been observed in amphibian (19), avian (11), and a variety of mammalia cells, particularly in hepatocytes (5,28,30,38), cells of renal collecting tubules (6), and cardiac muscle cells (8), partly under normal, partly under various pathological conditions . With respect to the origin of intranuclear glycogen, translocations of cytoplasmic glycogen particles into the nuclear compartment (30,40) free wild-type Ehrlich-Lettrt; ascites tumor, which was manipulated pharmacologically by means of N-methyl-colchicamide (27). A genome mutation of HD33 cells is associated with various phenotypical deviations from the wild type,' among which a pronounced nuclear and/or cytoplasmic glycogen storage is the most conspicuous (46). Characteristically, between days 4 and 6 after transplantation, glycogen deposits of increasing size are located chiefly within the tumor cell nuclei . Additional cytoplasmic glycogen storage is restricted to later stages oftumor development (46). On days 5 and 6, pronounced nuclear glycogen storage coincides with minimal cytoplasmic glycogen deposition in interphase cells . Thus, cells at this stage of tumor development provide a unique substrate for an analysis of their nuclear glycogen metabolism.In previous communications (...

Influence of age on nuclear bodies and nuclear volume in pituicytes of the rat neurohypophysis

“…It is reasonable to assume that glycogen-containing nuclei of pituicytes have the enzymes of glycogen synthesis, which must enter the nucleus by diffusion from the cytoplasm. This is consistent with the biochemical and autoradiographic evidence (Zimmermann et al, 1976a;Granzow et al, 1981) of glycogen synthesis and the presence of glycogen synthase in nuclei of Ehrlich ascites cells. Although the presence of intranuclear glycogen in pituicytes is exceptional, it probably reflects the metabolic plasticity of these cells which, under certain metabolic conditions, allows the translocation of enzymes of glycogen synthesis from the cytoplasm into the nucleus.…”

Metabolic properties of chicken embryonic stem cells

“…In fact, a number of studies have reported glycogen in association with the nuclear envelope, the endoplasmic reticulum, and the annulate lamellae of embryonic and transformed cells [14,[39][40][41]. Glycogen has also been reported inside the nucleus [42][43][44][45][46]. Moreover, glycogen consistently appears in the Xenopus embryo during the cleavage stage [47].…”

Nuclear assembly with lambda DNA in fractionated Xenopus egg extracts: an unexpected role for glycogen in formation of a higher order chromatin intermediate

“…A number of studies have reported glycogen in association with the nuclear envelope, the endoplasmic reticulum, and with annulate lamellae of embryonic and transformed cells (Coimbra and Lebland, 1966;Flaks, 1968;Eyal-Giladi et al, 1985;Kessel, 1989;Hubbard et al, 1990;Kessel and Beams, 1990). Glycogen has also been reported inside the nucleus (Himes and Pollister, 1962;Karasaki, 1971;Mori et al, 1970;Granzow et al, 1981;Kopun et al, 1989; for a review of intranuclear glycogen see Ferrans et al, 1975). These reports of glycogen in close apposition with nuclear envelopes and annulate lamellae may represent a structural association, or merely a circumstantial association.…”