Modulation of Differentiation-related Gene 1 Expression by Cell Cycle Blocker Mimosine, Revealed by Proteomic Analysis

Abstract

L-Mimosine, a plant amino acid, can reversibly block mammalian cells at late G 1 phase and has been found to affect translation of mRNAs of the cyclin-dependent kinase inhibitor p27, eIF3a (eIF3 p170), and ribonucleotide reductase M2. The effect of mimosine on the expression of these genes may be essential for the G 1 phase arrest. To determine additional genes that may be early respondents to the mimosine treatment, we performed two-dimensional gel electrophoretic analysis of [35 S]methionine-labeled cell lysates followed by identification of the altered protein spots by LC-tandem mass spectrometry. In this study, the synthesis of two protein spots (MIP42 and MIP17) was found to be enhanced by mimosine, whereas the formation of another protein spot (MSP17) was severely blocked following mimosine treatment. These protein spots, MIP42, MIP17, and MSP17, were identified to be differentiation-related gene 1 (Drg-1; also called RTP, cap43, rit42, Ndrg-1, and PROXY-1), deoxyhypusine-containing eIF5A intermediate, and mature hypusine-containing eIF5A, respectively. The effect of mimosine on eIF5A maturation was due to inhibition of deoxyhypusine hydroxylase, the enzyme catalyzing the final step of hypusine biosynthesis in eIF5A. The mimosine-induced expression of Drg-1 was mainly attributable to increased transcription likely by the c-Jun/AP-1 transcription factor. Because induction of Drg-1 is an early event after mimosine treatment and is observed before a notable reduction in the steady-state level of mature eIF5A, eIF5A does not appear to be involved in the modulation of Drg-1 expression. Molecular & Cellular Proteomics 4:993-1001, 2005.

Tuning Cell Cycle Regulation with an Iron Key

“…Furthermore, there is work demonstrating that Fe-depletion by DFO can up-regulate ATF3. 198 This latter observation appears somewhat paradoxical, as the observed up-regulation of Ndrg-1 after Fe-depletion 102,110 would be expected to downregulate ATF3 levels.…”

“…102 The effect of Fe-deprivation on up-regulated Ndrg-1 levels in HeLa cells was confirmed by others in later studies using the chelator, mimosine. 110 Both HIF-1a-dependent and -independent mechanisms were found to be responsible for the up-regulation of Ndrg-1 following Fe-depletion. 102 The addition of Fe salts to cells after Fe chelation was found to reverse Ndrg-1 upregulation, confirming that Fe-depletion increased Ndrg-1 expression.…”

“…[182][183][184][191][192][193][194] Iron-depletion markedly up-regulates Ndrg-1 mRNA and protein expression in a number of neoplastic cell types, and hence, may be significant for understanding the mechanisms involved in the inhibition of proliferation by Fe chelators. 102,110 High expression of Ndrg-1 is associated with greater survival and less aggressive tumors in prostate cancer patients. 192 There is also a significant inverse correlation of Ndrg-1 expression with depth of invasion in pancreatic adenocarcinoma patients.…”

“…101 [108][109][110] GADD45a, 72 hypoxia inducible factor-1a (HIF-1a), N-myc downstream regulatory gene-1 (Ndrg-1) 102 and pRb. 98,111 By altering the expression and/or function of the above molecules, Fe-depletion is able to effectively inhibit the growth of tumor cells.…”

Gelsolin Induces Promonocytic Leukemia Differentiation Accompanied by Upregulation of p21CIP1

“…There is evidence implicating other tumor suppressors, such as, the retinoblastoma gene (Goodrich, 2006), p53 (Spike and Wahl, 2011), DCC gene (Zhao, 2012), and Differentiation-Related-Gene-1 (Drg-1) (Dong et al, 2005) in cellular differentiation. Results of the molecular control of changes in the normal developmental program in myeloid leukaemia have shown that genetic abnormalities which give rise to malignancy can be bypassed, and their effects nullified, by inducing differentiation, which stops cells from multiplying (Lai et al, 2012).…”