Heteromeric complexes of heat shock protein 70 (HSP70) family members, including Hsp70B′, in differentiated human neuronal cells

Abstract

Human neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis have been termed "protein misfolding disorders." Upregulation of heat shock proteins that target misfolded aggregation-prone proteins has been proposed as a potential therapeutic strategy to counter neurodegenerative disorders. The heat shock protein 70 (HSP70) family is well characterized for its cytoprotective effects against cell death and has been implicated in neuroprotection by overexpression studies. HSP70 family members exhibit sequence and structural conservation. The significance of the multiplicity of HSP70 proteins is unknown. In this study, coimmunoprecipitation was employed to determine if association of HSP70 family members occurs, including Hsp70B′ which is present in the human genome but not in mouse and rat. Heteromeric complexes of Hsp70B′, Hsp70, and Hsc70 were detected in differentiated human SH-SY5Y neuronal cells. Hsp70B′ also formed complexes with Hsp40 suggesting a common co-chaperone for HSP70 family members.

Induction of heat shock proteins in differentiated human neuronal cells following co-application of celastrol and arimoclomol

“…1a, inclusion of arimoclomol with celastrol enhanced the induction of several Hsps, compared to celastrol alone. This included the little studied HSPA6 that is found in the human genome but not in the genomes of rat and mouse and hence is lacking in current animal models of neurodegenerative diseases (Chow and Brown 2007;Noonan et al 2007a, b;Chow et al 2010). In addition to HSPA6, enhanced induction was also observed following co-application of celastrol and arimoclomol for HSPA1A (Hsp70-1), DNAJB1 (Hsp40), HO-1 (Hsp32), and HSPB1 (Hsp27).…”

“…This includes upregulation of HSPA6 (Hsp70B'), a little studied member of the HSPA (Hsp70) family that is present in the human genome, but not in rat and mouse (Chow and Brown 2007;Noonan et al 2007aNoonan et al , b, 2008aChow et al 2010;Ramirez et al 2014). Recently, we have demonstrated a unique feature of HSPA6, namely localization to transcription sites in human neuronal cells during recovery from stress-induced inhibition (Khalouei et al 2014), a feature that is missing in current animal models of neurodegenerative diseases which lack HSPA6.…”

“…Cells were immersed in a circulating water bath calibrated at 43°C ± 0.1°C for 20 min (Chow et al 2010) and returned to a humidified 5 % CO 2 atmosphere at 37°C for 24 h before being harvested for Western blotting. The start of the 20-min heat shock represents the zero time point (t = 0).…”

Dynamics of the association of heat shock protein HSPA6 (Hsp70B’) and HSPA1A (Hsp70–1) with stress-sensitive cytoplasmic and nuclear structures in differentiated human neuronal cells

“…In the present study, live imaging and FRAP were utilized to further knowledge of HSPA6 (Hsp70B'), a little studied member of the HSPA (Hsp70) multigene family that is present in the human genome but absent in the genomes of mouse and rat (Chow and Brown 2007;Noonan et al 2007a;Noonan et al 2007b;Noonan et al 2008a;Noonan et al 2008b;Chow et al 2010;Ramirez et al 2015;Deane and Brown 2016). Following thermal stress, changes in the intracellular localization of HSPA6, and the more widely studied HSPA1A (Hsp70-1), were visualized in living differentiated human neuronal SH-SY5Y cells, with FRAP employed to compare the dynamics of the exchange of these two Hsps with stresssensitive cytoplasmic and nuclear structures.…”

“…Heat shock proteins (Hsps) are cellular repair agents that counter the effects of protein misfolding, and their upregulation has been proposed as a potential strategy to counter neurodegenerative disorders (Muchowski and Wacker 2005;Asea and Brown 2008;Pratt et al 2015). The HSPA (Hsp70) family has been widely studied, particularly HSPA1A (Hsp70-1), however HSPA6 (Hsp70B') has received comparatively little attention (Chow and Brown 2007;Noonan et al 2007a;Noonan et al 2007b;Noonan et al 2008a;Noonan et al 2008b;Chow et al 2010;Ramirez et al 2015;Deane and Brown 2016). Interestingly, HSPA6 is present in the human genome and absent in the genomes of mouse and rat.…”