title: Expression profiling and biochemical analysis suggest stress response as a potential mechanism inhibiting proliferation of polyamine-depleted cells.
abstract: Polyamines are small organic polycations that are absolutely required for cell growth and proliferation; yet the basis for this requirement is mostly unknown. Here, we combined a genome-wide expression profiling with biochemical analysis to reveal the molecular basis for inhibited proliferation of polyamine-depleted cells. Transcriptional responses accompanying growth arrest establishment in polyamine-depleted cells or growth resumption following polyamine replenishment were monitored and compared. Changes in the expression of genes related to various fundamental cellular processes were established. Analysis of mirror-symmetric expression patterns around the G(1)-arrest point identified a set of genes representing a stress-response signature. Indeed, complementary biochemical analysis demonstrated activation of the PKR-like endoplasmic reticulum kinase arm of the unfolded protein response and of the stress-induced p38 MAPK. These changes were accompanied by induction of key growth-inhibitory factors such as p21 and Gadd45a and reduced expression of various cyclins, most profoundly cyclin D1, setting the basis for the halted proliferation. However, although the induced stress response could arrest growth, polyamine depletion also inhibited proliferation of PKR-like endoplasmic reticulum kinase and p38α-deficient cells and of cells harboring a nonphosphorylatable mutant eIF2α (S51A), suggesting that additional yet unidentified mechanisms might inhibit proliferation of polyamine-depleted cells. Despite lengthy persistence of the stress and activation of apoptotic signaling, polyamine-depleted cells remained viable, apparently due to induced expression of protective genes and development of autophagy.
authors.affiliation: Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Guy
authors.initials: G
authors.lastname: Landau
authors.forename: Avichai
authors.initials: A
authors.lastname: Ran
authors.forename: Zippi
authors.initials: Z
authors.lastname: Bercovich
authors.forename: Ester
authors.initials: E
authors.lastname: Feldmesser
authors.forename: Shirley
authors.initials: S
authors.lastname: Horn-Saban
authors.forename: Eduard
authors.initials: E
authors.lastname: Korkotian
authors.forename: Jasmine
authors.initials: J
authors.lastname: Jacob-Hirsh
authors.forename: Gideon
authors.initials: G
authors.lastname: Rechavi
authors.forename: David
authors.initials: D
authors.lastname: Ron
authors.forename: Chaim
authors.initials: C
authors.lastname: Kahana
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D001343:Autophagy / Q000502:physiology; D015317:Biogenic Polyamines / Q000378:metabolism*; D059585:G1 Phase Cell Cycle Checkpoints / Q000502:physiology*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000502:physiology*; D051379:Mice; D041681:NIH 3T3 Cells; D015398:Signal Transduction / Q000502:physiology; D013312:Stress, Physiological / Q000502:physiology*; D014158:Transcription, Genetic / Q000502:physiology*; D056811:Unfolded Protein Response / Q000502:physiology
chemical_list: D015317:Biogenic Polyamines