Cell stress and translational inhibitors transiently increase the abundance of mammalian SINE transcripts

Abstract

The abundance of Alu RNA is transiently increased by heat shock in human cell lines. This effect is specific to Alu repeats among Pol III transcribed genes, since the abundance of 7SL, 7SK, 5S and U6 RNAs is essentially unaffected by heat shock. The rapid induction of Alu expression precedes the heat shock induction of mRNAs for the ubiquitin and HSP 70 heat shock genes. Heat shock mimetics also transiently induce Alu expression indicating that increased Alu expression is a general cell-stress response. Cycloheximide treatment rapidly and transiently increases the abundance of Alu RNA. Again, compared with other genes transcribed by Pol III, this increase is specific to Alu. However, as distinguished from the cell stress response, cycloheximide does not induce expression of HSP 70 and ubiquitin mRNAs. Puromycin also increases Alu expression, suggesting that this response is generally caused by translational inhibition. The response of mammalian SINEs to cell stress and translational inhibition is not limited to SINEs which are Alu homologues. Heat shock and cycloheximide each transiently induce Pol III directed expression of B1 and B2 RNAs in mouse cells and C-element RNA in rabbit cells. Together, these three species exemplify the known SINE composition of placental mammals, suggesting that mammalian SINEs are similarly regulated and may serve a common function.

Eukaryotic regulatory RNAs: an answer to the ‘genome complexity’ conundrum

“…Expression of this RNA is increased up to 100-fold in response to environmental stresses such as heat shock (Liu et al 1995;Allen et al 2004). Coimmunoprecipitation and binding experiments have provided evidence that B2 RNA associates with RNA pol II upon heat shock, and in vivo and in vitro transcription experiments have revealed that B2 RNA inhibits RNA pol II by preventing the formation of active preinitiation complexes Espinoza et al 2004).…”

Useful ‘junk’: Alu RNAs in the human transcriptome

“…The excess of SRP9/14 over SRP was only observed in immortalized cell lines [12], and the expression levels of SRP9/14, relative to SRP, will have to be investigated in different tissues and under different physiological conditions to better characterize the potential regulation of Alu RNA activity. Moreover, as most of the previous studies concerning Alu RNA transcription were performed using cultured cancer cells [8,9,15,18,19], it would also be interesting to measure the level of Alu RNA in different tissues or in cultured primary cells. It was indeed recently shown that the level of Alu transcripts is much lower in normal than in cancerous hepatic cells [20].…”

CAN—a pan-carnivore SINE family

“…The deviation of SINEs from ancestor RNA in the 3Ј-region should be related either to the retroposition process (e.g., acquiring higher affinity to the reverse transcriptase) or to the control of transcription. Indeed, most of the time transcription of short retroposons is repressed except for special conditions such as early embryogenesis (Bachvarova 1988;Grigoryan et al 1985) or stress (Liu et al 1995;Panning and Smiley 1993).…”