scholarly journals Studies of non-metabolizable polyamines that support growth of SV-3T3 cells depleted of natural polyamines by exposure to α-difluoromethylornithine

1988 ◽  
Vol 254 (2) ◽  
pp. 373-378 ◽  
Author(s):  
S Nagarajan ◽  
B Ganem ◽  
A E Pegg
Keyword(s):  
Cell Growth ◽  
Physiological Role ◽  
3T3 Cells ◽  
Polyamine Synthesis ◽  
Spermine Synthase ◽  
Support Cell ◽  
Polyamine Derivatives ◽  
Metabolic Interconversion

A number of synthetic polyamine derivatives that included five achiral gem-dimethylspermidines and two analogous tetramethylated spermines were tested for their abilities to serve as substrates for enzymes metabolizing polyamines and for their capacities to substitute for the natural polyamines in cell growth. It was found that none of the compounds were effective substrates for spermine synthase, and only one, namely 8,8-dimethylspermidine, was a substrate for spermidine/spermine N1-acetyltransferase. However, all of the spermidine derivatives and 1,1,12,12-tetramethylspermine were able to support the growth of SV-3T3 cells in which endogenous polyamine synthesis was prevented by the addition of alpha-difluoromethylornithine. These results suggest that either spermidine or spermine can support cell growth without the need for metabolic interconversion. In contrast with the result with 1,1,12,12-tetramethylspermine, 3,3,10,10-tetramethylspermine did not restore growth of polyamine-depleted SV-3T3 cells. Comparison of the properties of these derivatives may prove valuable in understanding the physiological role of polyamines.

Calcium pools, calcium entry, and cell growth

1996 ◽  
Vol 16 (2) ◽  
pp. 139-157 ◽  
Author(s):  
Donald L. Gill ◽  
Richard T. Waldron ◽  
Krystyna E. Rys-Sikora ◽  
Carmen A. Ufret-Vincenty ◽  
Matthew N. Graber ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Growth ◽  
Morphological Analysis ◽  
Essential Fatty Acids ◽  
Physiological Role ◽  
Wide Distribution ◽  
Short Term ◽  
Growth State

The Ca2+ pump and Ca2+ release functions of intracellular Ca2+ pools have been well characterized. However, the nature and identity of Ca2+ pools as well as the physiological implications of Ca2+ levels within them, have remained elusive. Ca2+ pools appear to be contained within the endoplasmic reticulum (ER); however, ER is a heterogeneous and widely distributed organelle, with numerous other functions than Ca2+ regulation. Studies described here center on trying to determine more about subcellular distribution of Ca2+ pools, the levels of Ca2+ within Ca2+ pools, and how these intraluminal Ca2+ levels may be physiologically related to ER function. Experiments utilizing in situ high resolution subcellular morphological analysis of ER loaded with ratiometric fluroescent Ca2+ dyes, indicate a wide distribution of inositol 1,4,5-trisphosphate (InsP3)-sensitive Ca2+ pools within cells, and large changes in the levels of Ca2+ within pools following InsP3-mediated Ca2+ release. Such changes in Ca2+ may be of great significance to the translation, translocation, and folding of proteins in ER, in particular with respect to the function of the now numerously described luminal Ca2+-sensitive chaperonin proteins. Studies have also focussed on the physiological role of pool Ca2+ changes with respect to cell growth. Emptying of pools using Ca2+ pump blockers can result in cells entering a stable quiescent G0-like growth state. After treatment with the irreversible pump blocker, thapsigargin, cells remain in this state until they are stimulated with essential fatty acids whereupon new pump protein is synthesized, functional Ca2+ pools return, and cells reenter the cell cycle. During the Ca2+ pool-depleted growth-arrested state, cells express a Ca2+ influx channel that is distinct from the store-operated Ca2+ influx channels activated after short-term depletion of Ca2+ pools. Overall, these studies indicate that significant changes in intraluminal ER Ca2+ do occur and that such changes appear linked to alteration of essential ER functions as well as to the cell cycle-state and the growth of cells.

Effect of polyamine depletion on caspase activation: a study with spermine synthase-deficient cells

2001 ◽  
Vol 355 (1) ◽  
pp. 199-206 ◽  
Author(s):  
Claudio STEFANELLI ◽  
Carla PIGNATTI ◽  
Benedetta TANTINI ◽  
Monia FATTORI ◽  
Ivana STANIC ◽  
...  
Keyword(s):  
Uv Irradiation ◽  
Normal Male ◽  
Caspase Activity ◽  
Caspase Activation ◽  
Embryonic Fibroblasts ◽  
Polyamine Synthesis ◽  
Spermine Synthase ◽  
Cell Processes ◽  
Mutant Male

Activation of the caspase proteases represents a central point in apoptosis. The requirement for spermine for the processes leading to caspase activation has been studied in transformed embryonic fibroblasts obtained from gyro (Gy) mutant male mice. These cells lack spermine synthase activity and thus provide a valuable model to study the role of spermine in cell processes. Gy fibroblasts do not contain spermine and have a higher spermidine content. However, when compared with fibroblasts obtained from normal male littermates (N cells), Gy fibroblasts were observed to grow normally. The lack of spermine did not affect the expression of Bcl-2, and caspases 3 and 9 were activated by etoposide in both N and Gy cells, indicating that spermine is dispensable for caspase activation. Spermine deficiency did not significantly influence caspase activity in cells treated with etoposide, cycloheximide or staurosporine, but sensitized the cells to UV irradiation, which triggered significantly higher caspase activity in Gy cells compared with N cells. α-Difluoromethylornithine (DFMO), an inhibitor of polyamine synthesis that is able to deplete cells of putrescine and spermidine, but usually does not influence spermine content, was able to produce a more complete polyamine depletion in Gy cells. This depletion, which included spermine deficiency, dramatically increased caspase activation and cell death in Gy fibroblasts exposed to UV irradiation. On the other hand, in either N or Gy cells, DFMO treatment did not influence caspase activity triggered by staurosporine, but inhibited it when the inducers were cycloheximide or etoposide. In Gy cells depleted of polyamines by DFMO, polyamine replenishment with either spermidine or spermine was sufficient to restore caspase activity induced by etoposide, indicating that, in this model, polyamines have an interchangeable role in supporting caspase activation. Therefore, spermine is not required for such activation, and the effect and specificity of polyamine depletion on caspase activity may be very different, depending on the role of polyamines in the specific death pathways engaged by different stimuli. Some inducers of apoptosis, for example etoposide, absolutely require polyamines for caspase activation, yet the lack of polyamines, particularly spermine, strongly increases caspase activation when induced by UV irradiation.

scholarly journals A Unifying Model for the Role of Polyamines in Bacterial Cell Growth, the Polyamine Modulon

2004 ◽  
Vol 279 (44) ◽  
pp. 46008-46013 ◽  
Author(s):  
Madoka Yoshida ◽  
Keiko Kashiwagi ◽  
Ai Shigemasa ◽  
Shiho Taniguchi ◽  
Kaneyoshi Yamamoto ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Protein Synthesis ◽  
Cell Growth ◽  
Iron Uptake ◽  
Physiological Role ◽  
Normal Position ◽  
Specific Proteins ◽  
The Common ◽  
Cell Growth And Viability

We reported previously that the synthesis of specific proteins such as OppA, Cya, and RpoS (σ38), which are important for cell growth and viability, is stimulated by polyamines at the level of translation. In this study we found that the synthesis of FecI and Fis was also stimulated by polyamines at the level of translation. The FecI and Fis proteins enhance the expression of mRNAs that are involved in iron uptake and energy metabolism and the expression of rRNA and some tRNAs. The Shine-Dalgarno (SD) sequence of their mRNAs was not obvious or was not located at the usual position. When the SD sequences were created at the normal position on these mRNAs, protein synthesis was no longer influenced by polyamines. Thus, the common characteristic of these mRNAs was to have a weak or ineffective SD sequence. We propose that a group of genes whose expression is enhanced by polyamines at the level of translation be referred to as a “polyamine modulon.” By DNA microarray, we found that 309 of 2,742 mRNA species were upregulated by polyamines. Among the 309 up-regulated genes, transcriptional enhancement of at least 58 genes might be attributable to increased levels of the transcription factors Cya, RpoS, FecI, and Fis, which are all organized in the polyamine modulon. This unifying molecular mechanism is proposed to underlie the physiological role of polyamines in controlling the growth ofEscherichia coli.

scholarly journals PTRF/Cavin-1 promotes efficient ribosomal RNA transcription in response to metabolic challenges

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Libin Liu ◽  
Paul F Pilch
Keyword(s):  
Cell Growth ◽  
Ribosomal Rna ◽  
Ribosome Biogenesis ◽  
Critical Role ◽  
Physiological Role ◽  
Rna Transcription ◽  
Post Translational Modifications ◽  
Acute Response ◽  
Polymerase I

Ribosomal RNA transcription mediated by RNA polymerase I represents the rate-limiting step in ribosome biogenesis. In eukaryotic cells, nutrients and growth factors regulate ribosomal RNA transcription through various key factors coupled to cell growth. We show here in mature adipocytes, ribosomal transcription can be acutely regulated in response to metabolic challenges. This acute response is mediated by PTRF (polymerase I transcription and release factor, also known as cavin-1), which has previously been shown to play a critical role in caveolae formation. The caveolae–independent rDNA transcriptional role of PTRF not only explains the lipodystrophy phenotype observed in PTRF deficient mice and humans, but also highlights its crucial physiological role in maintaining adipocyte allostasis. Multiple post-translational modifications of PTRF provide mechanistic bases for its regulation. The role of PTRF in ribosomal transcriptional efficiency is likely relevant to many additional physiological situations of cell growth and organismal metabolism.

scholarly journals Functional Analysis of the Leukemia Protein ELL: Evidence for a Role in the Regulation of Cell Growth and Survival

2001 ◽  
Vol 21 (5) ◽  
pp. 1672-1681 ◽  
Author(s):  
Ricky W. Johnstone ◽  
Mark Gerber ◽  
Theresa Landewe ◽  
Anne Tollefson ◽  
William S. Wold ◽  
...  
Keyword(s):  
Cell Death ◽  
Cell Growth ◽  
Rna Polymerase Ii ◽  
Physiological Role ◽  
Chromosomal Dna ◽  
Growth And Survival ◽  
Regulate Cell Growth ◽  
Inducible Cell Line ◽  
Cell Growth And Survival

ABSTRACT The ELL gene encodes an RNA polymerase II transcription factor that frequently undergoes translocation with the MLLgene in acute human myeloid leukemia. Here, we report that ELL can regulate cell proliferation and survival. In order to better understand the physiological role of the ELL protein, we have developed an ELL-inducible cell line. Cells expressing ELL were uniformly inhibited for growth by a loss of the G1 population and an increase in the G2/M population. This decrease in cell growth is followed by the condensation of chromosomal DNA, activation of caspase 3, poly(ADP ribose) polymerase cleavage, and an increase in sub-G1 population, which are all indicators of the process of programmed cell death. In support of the role of ELL in induction of cell death, expression of an ELL antisense RNA or addition of the caspase inhibitor ZVAD-fmk results in a reversal of ELL-mediated death. We have also demonstrated that the C-terminal domain of ELL, which is conserved among the ELL family of proteins that we have cloned (ELL, ELL2, and ELL3), is required for ELL's activity in the regulation of cell growth. These novel results indicate that ELL can regulate cell growth and survival and may explain how ELL translocations result in the development of human malignancies.

scholarly journals Increase in S-adenosylmethionine decarboxylase in SV-3T3 cells treated with S-methyl-5′-methylthioadenosine

1987 ◽  
Vol 244 (1) ◽  
pp. 49-54 ◽  
Author(s):  
A E Pegg ◽  
R Wechter ◽  
A Pajunen
Keyword(s):  
Translation Efficiency ◽  
3T3 Cells ◽  
Enzyme Protein ◽  
Polyamine Synthesis ◽  
Adenosylmethionine Decarboxylase ◽  
Spermine Synthase ◽  
Additional Stabilization ◽  
Key Enzyme ◽  
Translatable Mrna ◽  
Synthase Inhibitor

Treatment of SV-3T3 cells with the spermine synthase inhibitor S-methyl-5′-methylthioadenosine [AdoS+(CH3)2] led to a large increase in the activity of S-adenosylmethionine decarboxylase (AdoMetDC) without affecting ornithine decarboxylase. The elevation of AdoMetDC activity was due to an increased amount of enzyme protein, as demonstrated by radioimmunoassay and by immunoblotting. The increase in AdoMetDC protein was caused by at least three factors: an increase in the amount of translatable mRNA, an increased translation efficiency of the mRNA and an increase in the half-life of the protein. The depletion of spermine brought about by AdoS+(CH3)2 appeared to be responsible for the increased synthesis of AdoMetDC and for part of the decrease in its rate of degradation. An additional stabilization of the enzyme protein was probably due to the binding of AdoS+(CH3)2, which is also a weak inhibitor of AdoMetDC. These results demonstrate the importance of cellular spermine concentrations in regulating the activity of AdoMetDC, which is a key enzyme controlling polyamine synthesis.

scholarly journals Role of unsaturated derivatives of spermidine as substrates for spermine synthase and in supporting growth of SV-3T3 cells

1991 ◽  
Vol 274 (1) ◽  
pp. 167-171 ◽  
Author(s):  
A E Pegg ◽  
S Nagarajan ◽  
S Naficy ◽  
B Ganem
Keyword(s):  
Feedback Regulation ◽  
3T3 Cells ◽  
Spermine Synthase ◽  
Polyamine Transport ◽  
Spermidine Analogues ◽  
Derivatives Of ◽  
Cis Isomer ◽  
Endogenous Synthesis ◽  
Stimulation Of

Synthetic unsaturated analogues of the natural polyamine were examined as possible substrates for spermine synthase and as replacements for spermidine in supporting the growth of SV-3T3 cells. It was found that N-(3-aminopropyl)-1,4-diamino-cis-but-2-ene [the cis isomer of the alkene analogue of spermidine] was a good substrate for spermine synthase, but that the trans isomer [N-(3-aminopropyl)-1,4-diamino-trans-but-2-ene] and the alkene analogue [N-(3-aminopropyl)-1,4-diaminobut-2-yne] were not substrates. These results provide the first demonstration of stereospecificity in the spermine synthase reaction. All three of the unsaturated spermidine analogues described above and the cis-alkene analogue of spermine [N1N4-bis-(3-aminopropyl)-1,4-diamino-cis-but-2-ene] were able to support the growth of SV-3T3 cells that were prevented from the endogenous synthesis of spermidine by treatment with alpha-difluoromethylornithine. Since N-(3-aminopropyl)-1,4-diamino-trans-but-2-ene] and N-(3-aminopropyl)-1,4-diaminobut-2-yne were not converted into a spermine derivative, it is apparent that this conversion is not needed for the stimulation of growth. However, since N1N4-bis-(3-aminopropyl)-1,4-diamino-cis-but-2-ene was also able to support growth and was not degraded to the spermidine derivative, it appears that either polyamine can be effective in this respect. All of the unsaturated analogues tested accumulated in the SV-3T3 cells to a much greater extent than spermidine itself. This indicates that these compounds are substrates for the polyamine transport system, but that they are less effective than the natural polyamines in the feedback regulation of this system.

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