MSc Exit Seminar – Larissa Becirovic (Brown lab)

MSc Exit Seminar

Thursday July 28^th, 10:10 am – Room SW 403, University of Toronto at Scarborough

Larissa Becirovic (Brown lab)

“Localization of Heat Shock Protein HSPA6 (HSP70B’) to the Periphery of Nuclear Speckles is Disrupted by a Transcription Inhibitor Following Thermal Stress in Human Neuronal Cells“

Abstract

Heat shock proteins (Hsps) are a set of highly conserved proteins involved in cellular repair and protective mechanisms. The localization of inducible members of the HSPA (HSP70) family can be used as an index to identify stress-sensitive sites in differentiated human neuronal cells. Following thermal stress, the little studied HSPA6 (HSP70B’) demonstrated localization to the periphery of nuclear speckles (perispeckles) that are sites of transcription factories, however the widely studied HSPA1A (HSP70-1) did not. The localization of HSPA6 to perispeckles suggests that HSPA6 may be involved in the recovery of transcription in neuronal cells following exposure to thermal stress. Triptolide, a fast-acting transcription inhibitor, knocked down levels of the large subunit of RNA polymerase II, RPB1, during the time-frame when HSPA6 localized to perispeckles following thermal stress. Triptolide was administered to heat shocked human neuronal SH-SY5Y cells stably transfected with YFP-tagged HSPA6. Fluorescent confocal microscopy demonstrated that YFP-HSPA6 did not localize to perispeckles, suggesting the involvement of HSPA6 in transcriptional recovery after thermal stress. Rapid transcriptional recovery of stressed neuronal cells may be beneficial to the human brain that engages in higher cognitive functions compared to mouse and rat. The HSPA6 gene is present in the human genome but not in the genomes of mouse and rat. Hence, current animal models of neurodegenerative diseases lack a potentially protective member of the HSPA family.