bims-polyam 2020-02-23 papers

Issue of 2020‒02‒23
six papers selected by
Alexander Ivanov
Engelhardt Institute of Molecular Biology

J Med Chem. 2020 Feb 18.

Serendipitous Discovery of Leucine and Methionine Depletion Agents During the Search for Polyamine Transport Inhibitors.

Chelsea Lynn Massaro, Jenna Thomas, Houssine Ikhlef, Sharifa Dinara, Sara Cronk, Holly Moots, Otto Phanstiel.

Targeting polyamine metabolism is a proven anticancer strategy. Cancers often escape the polyamine biosynthesis inhibitors by increased polyamine import. Therefore, there is much interest in identifying polyamine transport inhibitors (PTIs) to be used in combination therapies. In a search for new PTIs, we serendipitously discovered a LAT-1 efflux agonist, which induces intracellular depletion of methionine, leucine, spermidine, and spermine, but not putrescine. Since S-adenosylmethioninamine is made from methionine, a loss of intracellular methionine leads to an inability to biosynthesize spermidine and spermine. Importantly, we found that this methionine-depletion approach to polyamine depletion could not be rescued by exogenous polyamines, thereby obviating the need for a PTI. Using 3H-leucine (the gold standard for LAT-1 transport studies) and JPH-203 (a specific LAT-1 inhibitor), we showed that the efflux agonist did not inhibit the uptake of extracellular leucine, but instead facilitated the efflux of intracellular leucine pools.

DOI: https://doi.org/10.1021/acs.jmedchem.9b00568

Biotechnol Lett. 2020 Feb 20.

Altered gene expression in CHO cells following polyamine starvation.

Berta Capella Roca, Padraig Doolan, Niall Barron, Fiona O'Neill, Martin Clynes.

AIM: To investigate the impact of polyamine deprivation on the transcriptome of CHO cells RESULTS: Polyamines play a central but poorly-understood role in cell proliferation. Most studies to date have utilised chemical inhibitors to probe polyamine function. Here we exploit the fact that CHO cells grown in serum-free medium have an absolute requirement for putrescine supplementation due to their deficiency in activity of the enzyme arginase. A gene expression microarray (Affymetrix) analysis of CHO-K1 cells starved of polyamines for 3 days showed that cessation of growth, associated with increased G1/S transition and inhibition of M/G1 transition was accompanied by increased mRNA levels of mitotic complex checkpoint genes (Mad2l1, Tkk, Bub1b) and in the transition of G1- to S-phase (such as Skp2 and Tfdp1). mRNAs associated with DNA homologous recombination and repair (including Fanconi's anaemia-related genes) and with RNA splicing were consistently increased. Alterations in mRNA levels for genes related to protein processing in the ER, to ER stress, and to p53-related and apoptosis pathways were also observed. mRNAs showing highest levels of fold-change included several which code for membrane-localised proteins and receptors (Thbs1, Tfrc1, Ackr3, Extl1).CONCLUSIONS: Growth-arrest induced by polyamine deprivation was associated with significant alterations in levels of mRNAs associated with cell cycle progression, DNA repair, RNA splicing, ER trafficking and membrane signalling as well as p53 and apoptosis-related pathways.

Keywords: Chinese hamster ovary cells (CHO); Gene expression; Polyamines; Putrescine; Transcriptomics

DOI: https://doi.org/10.1007/s10529-020-02841-0

J Plant Physiol. 2019 Dec 17. pii: S0176-1617(19)30221-4. [Epub ahead of print]246-247 153092

Inhibitors of tri- and tetra- polyamine oxidation, but not diamine oxidation, impair the initial stages of wound-induced suberization.

Edward C Lulai, Linda L Olson, Karen K Fugate, Jonathan D Neubauer, Larry G Campbell.

The mechanisms regulating, and modulating potato wound-healing processes are of great importance in reducing tuber infections, reducing shrinkage and maintaining quality and nutritional value for growers and consumers. Wound-induced changes in tuber polyamine metabolism have been linked to the modulation of wound healing (WH) and in possibly providing the crucial amount of H2O2 required for suberization processes. In this investigation we determined the effect of inhibition of specific steps within the pathway of polyamine metabolism on polyamine content and the initial accumulation of suberin polyphenolics (SPP) during WH. The accumulation of SPP represents a critical part of the beginning or inchoate phase of tuber WH during closing-layer formation because it serves as a barrier to bacterial infection and is a requisite for the accumulation of suberin polyaliphatics which provide the barrier to fungal infection. Results showed that the inhibitor treatments that caused changes in polyamine content generally did not influence wound-induced accumulation of SPP. Such lack of correlation was found for inhibitors involved in metabolism and oxidation of putrescine (arginine decarboxylase, ornithine decarboxylase, and diamine oxidase). However, accumulation of SPP was dramatically reduced by treatment with guazatine, a potent inhibitor of polyamine oxidase (PAO), and methylglyoxal-bis(guanylhydrazone), a putative inhibitor of S-adenosylmethione decarboxylase which may also cross-react to inhibit PAO. The mode of action of these inhibitors is presumed to be blockage of essential H2O2 production within the WH cell wall. These results are of great importance in understanding the mechanisms modulating WH and ultimately controlling related infections and associated postharvest losses.

Keywords: Polyaliphatic; Polyphenolic; Suberin; Suberization

DOI: https://doi.org/10.1016/j.jplph.2019.153092

J Proteomics. 2020 Feb 12. pii: S1874-3919(20)30054-3. [Epub ahead of print] 103686

Proteomic analysis revealed different responses to hypergravity of soleus and extensor digitorum longus muscles in mice.

Takashi Ohira, Yoko Ino, Yusuke Nakai, Hironobu Morita, Ayuko Kimura, Yoichi Kurata, Hiroyuki Kagawa, Mitsuo Kimura, Kenji Egashira, Shunsuke Moriya, Kyoko Hiramatsu, Masao Kawakita, Yayoi Kimura, Hisashi Hirano.

Investigating protein abundance profiles is important to understand the differences in the slow and fast skeletal muscle characteristics. The profiles in soleus (Sol) and extensor digitorum longus (EDL) muscles in mice exposed to 1 g or 3 g for 28 d were compared. The biological implications of the profiles revealed that hypergravity exposure activated a larger number of pathways involved in protein synthesis in Sol. In contrast, the inactivation of signalling pathways involved in oxidative phosphorylation were conspicuous in EDL. These results suggested that the reactivity of molecular pathways in Sol and EDL differed. Additionally, the levels of spermidine synthase and spermidine, an important polyamine for cell growth, increased in both muscles following hypergravity exposure, whereas the level of spermine oxidase (SMOX) increased in EDL alone. The SMOX level was negatively correlated with spermine content, which is involved in muscle atrophy, and was higher in EDL than Sol, even in the 1 g group. These results indicated that the contribution of SMOX to the regulation of spermidine and spermine contents in Sol and EDL differed. However, contrary to expectations, the difference in the SMOX level did not have a significant impact on the growth of these muscles following hypergravity exposure. SIGNIFICANCE: The skeletal muscle-specific protein abundance profiles result in differences in the characteristics of slow and fast skeletal muscles. We investigated differences in the profiles in mouse slow-twitch Sol and fast-twitch EDL muscles following 28-d of 1 g and 3 g exposure by LC-MS/MS analysis and label-free quantitation. A two-step solubilisation of the skeletal muscle proteins increased the coverage of proteins identified by LC-MS/MS analysis. Additionally, this method reduced the complexity of samples more easily than protein or peptide fractionation by SDS-PAGE and offline HPLC while maintaining the high operability of samples and was reproducible. A larger number of hypergravity-responsive proteins as well as a prominent increase in the wet weights was observed in Sol than EDL muscles. The biological implications of the difference in the protein abundance profiles in 1 g and 3 g groups revealed that the reactivity of each molecular pathway in Sol and EDL muscles to hypergravity exposure differed significantly. In addition, we found that the biosynthetic and interconversion pathway of polyamines, essential factors for cell growth and survival in mammals, was responsive to hypergravity exposure; spermidine and spermine contents in Sol and EDL muscles were regulated by different mechanisms even in the 1 g group. However, our results indicated that the difference in the mechanism regulating polyamine contents is unlikely to have a significant effect on the differences in Sol and EDL muscle growth following hypergravity exposure.

Keywords: Extensor digitorum longus; Hypergravity; Polyamine; Quantitative proteomic analysis; Soleus

DOI: https://doi.org/10.1016/j.jprot.2020.103686

Biomed Pharmacother. 2020 Feb 14. pii: S0753-3322(20)30121-9. [Epub ahead of print]125 109931

The effect of activated κ-opioid receptor (κ-OR) on the role of calcium sensing receptor (CaSR) in preventing hypoxic pulmonary hypertension development.

Juan Li, Min Jia, Manling Liu, Zhi Cao, Xinju Wang, Na Feng, Xiaoming Gu, Shumiao Zhang, Rong Fan, Haitao Guo, Yuemin Wang, Mingchao Liu, Jianming Pei.

κ-opioid receptor (κ-OR) plays a key role in preventing hypoxic pulmonary hypertension (HPH) development after activated by exogenous agonist U50,488H. Calcium sensing receptor (CaSR) activation induces HPH by promoting vasoconstriction and vascular remodeling. The activated κ-OR is reported to inhibit the expression of CaSR in pulmonary artery smooth muscle cells (PASMCs). Thus, in this study, we aimed to explore the effect of activated κ-OR on the role of CaSR in preventing HPH development. An HPH rat model was constructed using Sprague-Dawley rats. Changes in mean pulmonary arterial pressure (mPAP) and right ventricular pressure (RVP) mediated by κ-OR agonist U50,488H and CaSR inhibitor NPS2143 were observed. The effects of CaSR agonist spermine and inhibitor NPS2143 on pulmonary artery tension were tested. The expression and localization of κ-OR and CaSR were measured in isolated PASMCs. A cell-counting kit-8 assay was performed to evaluate the effect of spermine in PASMC proliferation. Expression of proliferating cell nuclear antigen (PCNA), Erk, and p-Erk was evaluated by western blot analysis. Results showed that κ-OR and CaSR were co-expressed and colocalized in PASMCs under normoxic and hypoxic conditions. Interactions between κ-OR and CaSR were also observed. Spermine improved vasoconstriction in the pulmonary artery in HPH rats, which was abolished by U50,488H. RVP and mPAP were significantly increased in HPH rats under CaSR stimulation, but were significantly reduced when the rats were pretreated with U50,488H and NPS2143 (P < 0.01). Spermine treatment significantly promoted PASMC proliferation, which was significantly inhibited by U50,488H, p38 inhibitor SB203580, JNK inhibitor SP600125, Erk inhibitor SCH772984, and MEK inhibitor U0126, especially Erk inhibitor (P < 0.01). Spermine significantly increased PCNA and P-Erk expression in hypoxic conditions, which was inhibited by U50,488H and NPS2143. κ-OR stimulation prevented HPH development via the CaSR/MAPK signaling pathway.

Keywords: CaSR; Hypoxic pulmonary hypertension; Spermine; κ-OR

DOI: https://doi.org/10.1016/j.biopha.2020.109931