Dataset Information

The small heat shock proteins ?B-crystallin (HSPB5) and Hsp27 (HSPB1) inhibit the intracellular aggregation of ?-synuclein.

ABSTRACT: Protein homeostasis, or proteostasis, is the process of maintaining the conformational and functional integrity of the proteome. Proteostasis is preserved in the face of stress by a complex network of cellular machinery, including the small heat shock molecular chaperone proteins (sHsps), which act to inhibit the aggregation and deposition of misfolded protein intermediates. Despite this, the pathogenesis of several neurodegenerative diseases has been inextricably linked with the amyloid fibrillar aggregation and deposition of ?-synuclein (?-syn). The sHsps are potent inhibitors of ?-syn aggregation in vitro. However, the limited availability of a robust, cell-based model of ?-syn aggregation has, thus far, restricted evaluation of sHsp efficacy in the cellular context. As such, this work sought to establish a robust model of intracellular ?-syn aggregation using Neuro-2a cells. Aggregation of ?-syn was found to be sensitive to inhibition of autophagy and the proteasome, resulting in a significant increase in the proportion of cells containing ?-syn inclusions. This model was then used to evaluate the capacity of the sHsps, ?B-c and Hsp27, to prevent ?-syn aggregation in cells. To do so, we used bicistronic expression plasmids to express the sHsps. Unlike traditional fluorescent fusion constructs, these bicistronic expression plasmids enable only individual transfected cells expressing the sHsps (via expression of the fluorescent reporter) to be analysed, but without the need to tag the sHsp, which can affect its oligomeric structure and chaperone activity. Overexpression of both ?B-c and Hsp27 significantly reduced the intracellular aggregation of ?-syn. Thus, these findings suggest that overexpressing or boosting the activity of sHsps may be a way of preventing amyloid fibrillar aggregation of ?-syn in the context of neurodegenerative disease.

SUBMITTER: Cox D

PROVIDER: S-EPMC5465035 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature

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The small heat shock proteins αB-crystallin (HSPB5) and Hsp27 (HSPB1) inhibit the intracellular aggregation of α-synuclein.

Cox Dezerae D Ecroyd Heath H

Cell stress & chaperones 20170323 4

Protein homeostasis, or proteostasis, is the process of maintaining the conformational and functional integrity of the proteome. Proteostasis is preserved in the face of stress by a complex network of cellular machinery, including the small heat shock molecular chaperone proteins (sHsps), which act to inhibit the aggregation and deposition of misfolded protein intermediates. Despite this, the pathogenesis of several neurodegenerative diseases has been inextricably linked with the amyloid fibrill ...[more]

PMID: 28337642

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Project description:We previously demonstrated that myocardial p38 mitogen-activated protein kinase (MAPK) and heat shock protein 27 (HSP27) are phosphorylated following cardioplegic arrest in patients undergoing cardiac surgery and correlate with reduced cardiac function. The following studies were performed to determine whether inhibition of p38 MAPK and/or overexpression of nonphosphorylatable HSP27 improves cardiac function following cardioplegic arrest. Langendorff-perfused isolated rat hearts were subjected to 2 h of intermittent cold cardioplegia followed by 30 min of reperfusion. Hearts were treated with (CP+SB) or without (CP) the p38 MAPK inhibitor SB-203580 (5 μM) supplied in the cardioplegia. Sham-treated hearts served as controls. In separate experiments, isolated rat ventricular myocytes infected with either green fluorescent protein (GFP) or a nonphosphorylatable HSP27 mutant (3A-HSP27) were subjected to 3 h of cold hypoxic cardioplegia and simulated reperfusion (CP) followed by video microscopy and length change measurements. Baseline parameters of cardiac function were similar between groups [left ventricular developed pressure (LVDP), 119 ± 4.9 mmHg; positive and negative first derivatives of LV pressure (± dP/dt), 3,139 ± 245 and 2, 314 ± 110 mmHg/s]. CP resulted in reduced cardiac function (LVDP, 72.2 ± 5.8 mmHg; ± dP/dt, 2,076 ± 231 and -1,317 ± 156 mmHg/s) compared with baseline. Treatment with 5 μM SB-203580 significantly improved CP-induced cardiac function (LVDP, 101.9 ± 0 mmHg; ± dP/dt, 2,836 ± 163 and -2,108 ± 120 mmHg/s; P = 0.03, 0.01, and 0.04, CP+SB vs. CP). Inhibition of p38 MAPK significantly lowered CP-induced p38 MAPK, HSP27, and αB-crystallin (cryAB) phosphorylation. In vitro CP decreased myocyte length changes from 10.3 ± 1.5% (GFP) to 5.7 ± 0.8% (GFP+CP). Infection with 3A-HSP27 completely rescued CP-induced decreased myocyte contraction (11.1 ± 1.0%). However, infection with 3A-HSP27 did not block the endogenous HSP27 response. We conclude that inhibition of p38 MAPK and subsequent HSP27 and cryAB phosphorylation and/or overexpression of nonphosphorylatable HSP27 significantly improves cardiac performance following cardioplegic arrest. Modulation of HSP27 phosphorylation may improve myocardial stunning following cardiac surgery.

Dataset Information

The small heat shock proteins ?B-crystallin (HSPB5) and Hsp27 (HSPB1) inhibit the intracellular aggregation of ?-synuclein.

Publications

The small heat shock proteins αB-crystallin (HSPB5) and Hsp27 (HSPB1) inhibit the intracellular aggregation of α-synuclein.

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