Cilia‐mediated heat shock protein 27 (hsp27) suppression modulates actin polymerization and organization in wild type mouse and oak ridge polycystic kidney (orpk) cells

Human heat shock protein 27 (Hsp27) is an oligomeric and cell survival protein that has been associated with several cancers including prostrate and breast cancer. It's a known anti-apoptotic protein that functions as a molecular chaperone for several proteins. Hsp27 characteristically binds and stabilizes numerous partially unfolded proteins preventing their degradation, and has been shown to prevent actin polymerization in vitro. Several actin-binding residues involved in this interaction have been identified at the N-terminal loop and highly conserved alpha crystallin domains of Hsp27. Multiple assays have demonstrated that this hydrophobic actin-binding site is also involved in other protein binding. We therefore propose a common substrate-binding region on Hsp27 and present a model of Hsp27 binding to actin.

Download Full-text

Modulation of cellular thermoresistance and actin filament stability accompanies phosphorylation-induced changes in the oligomeric structure of heat shock protein 27.

Molecular and Cellular Biology ◽

10.1128/mcb.15.1.505 ◽

1995 ◽

Vol 15 (1) ◽

pp. 505-516 ◽

Cited By ~ 456

Author(s):

J N Lavoie ◽

H Lambert ◽

E Hickey ◽

L A Weber ◽

J Landry

Keyword(s):

Heat Shock ◽

Heat Shock Protein ◽

Actin Filament ◽

Cellular Localization ◽

Chinese Hamster ◽

Heat Shock Protein 27 ◽

Cytochalasin D ◽

Wild Type ◽

Protective Function ◽

Hsp27 Phosphorylation

Phosphorylation of heat shock protein 27 (HSP27) can modulate actin filament dynamics in response to growth factors. During heat shock, HSP27 is phosphorylated at the same sites and by the same protein kinase as during mitogenic stimulation. This suggests that the same function of the protein may be activated during growth factor stimulation and the stress response. To determine the role of HSP27 phosphorylation in the heat shock response, several stable Chinese hamster cell lines that constitutively express various levels of the wild-type HSP27 (HU27 cells) or a nonphosphorylatable form of human HSP27 (HU27pm3 cells) were developed. In contrast to HU27 cells, which showed increased survival after heat shock, HU27pm3 cells showed only slightly enhanced survival. Evidence is presented that stabilization of microfilaments is a major target of the protective function of HSP27. In the HU27pm3 cells, the microfilaments were thermosensitized compared with those in the control cells, whereas wild-type HSP27 caused an increased stability of these structures in HU27 cells. HU27 but not HU27pm3 cells were highly resistant to cytochalasin D treatment compared with control cells. Moreover, in cells treated with cytochalasin D, wild-type HSP27 but not the phosphorylated form of HSP27 accelerated the reappearance of actin filaments. The mutations in human HSP27 had no effect on heat shock-induced change in solubility and cellular localization of the protein, indicating that phosphorylation was not involved in these processes. However, induction of HSP27 phosphorylation by stressing agents or mitogens caused a reduction in the multimeric size of the wild-type protein, an effect which was not observed with the mutant protein. We propose that early during stress, phosphorylation-induced conformational changes in the HSP27 oligomers regulate the activity of the protein at the level of microfilament dynamics, resulting in both enhanced stability and accelerated recovery of the filaments. The level of protection provided by HSP27 during heat shock may thus represent the contribution of better maintenance of actin filament integrity to overall cell survival.

Download Full-text

Overexpression of Wild-Type Heat Shock Protein 27 and a Nonphosphorylatable Heat Shock Protein 27 Mutant Protects Against Ischemia/Reperfusion Injury in a Transgenic Mouse Model

Circulation ◽

10.1161/01.cir.0000148825.99184.50 ◽

2004 ◽

Vol 110 (23) ◽

pp. 3544-3552 ◽

Cited By ~ 115

Author(s):

John M. Hollander ◽

Jody L. Martin ◽

Darrell D. Belke ◽

Brian T. Scott ◽

Eric Swanson ◽

...

Keyword(s):

Heat Shock ◽

Mouse Model ◽

Heat Shock Protein ◽

Reperfusion Injury ◽

Transgenic Mouse ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Transgenic Mouse Model ◽

Heat Shock Protein 27 ◽

Wild Type

Download Full-text

Cetuximab promotes SN38 sensitivity via suppression of heat shock protein 27 in colorectal cancer cells with wild-type RAS

Oncology Reports ◽

10.3892/or.2017.5734 ◽

2017 ◽

Vol 38 (2) ◽

pp. 926-932 ◽

Cited By ~ 1

Author(s):

Takashi Ishida ◽

Yoshiyuki Ishii ◽

Masashi Tsuruta ◽

Koji Okabayashi ◽

Shingo Akimoto ◽

...

Keyword(s):

Colorectal Cancer ◽

Heat Shock ◽

Heat Shock Protein ◽

Cancer Cells ◽

Heat Shock Protein 27 ◽

Wild Type ◽

Colorectal Cancer Cells

Download Full-text

Endothelium-targeted overexpression of heat shock protein 27 ameliorates blood–brain barrier disruption after ischemic brain injury

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1621174114 ◽

2017 ◽

Vol 114 (7) ◽

pp. E1243-E1252 ◽

Cited By ~ 44

Author(s):

Yejie Shi ◽

Xiaoyan Jiang ◽

Lili Zhang ◽

Hongjian Pu ◽

Xiaoming Hu ◽

...

Keyword(s):

Ischemic Stroke ◽

Brain Injury ◽

Heat Shock ◽

Heat Shock Protein ◽

Blood Brain Barrier ◽

Actin Polymerization ◽

Heat Shock Protein 27 ◽

Brain Barrier ◽

Blood Brain ◽

Neurological Conditions

The damage borne by the endothelial cells (ECs) forming the blood–brain barrier (BBB) during ischemic stroke and other neurological conditions disrupts the structure and function of the neurovascular unit and contributes to poor patient outcomes. We recently reported that structural aberrations in brain microvascular ECs—namely, uncontrolled actin polymerization and subsequent disassembly of junctional proteins, are a possible cause of the early onset BBB breach that arises within 30–60 min of reperfusion after transient focal ischemia. Here, we investigated the role of heat shock protein 27 (HSP27) as a direct inhibitor of actin polymerization and protectant against BBB disruption after ischemia/reperfusion (I/R). Using in vivo and in vitro models, we found that targeted overexpression of HSP27 specifically within ECs—but not within neurons—ameliorated BBB impairment 1–24 h after I/R. Mechanistically, HSP27 suppressed I/R-induced aberrant actin polymerization, stress fiber formation, and junctional protein translocation in brain microvascular ECs, independent of its protective actions against cell death. By preserving BBB integrity after I/R, EC-targeted HSP27 overexpression attenuated the infiltration of potentially destructive neutrophils and macrophages into brain parenchyma, thereby improving long-term stroke outcome. Notably, early poststroke administration of HSP27 attached to a cell-penetrating transduction domain (TAT-HSP27) rapidly elevated HSP27 levels in brain microvessels and ameliorated I/R-induced BBB disruption and subsequent neurological deficits. Thus, the present study demonstrates that HSP27 can function at the EC level to preserve BBB integrity after I/R brain injury. HSP27 may be a therapeutic agent for ischemic stroke and other neurological conditions involving BBB breakdown.

Download Full-text

Abstract 49: Endothelial-targeted Overexpression of Heat Shock Protein 27 Ameliorates Rapid Blood Brain Barrier Impairment and Improves Long Term Outcomes After Ischemia and Reperfusion

Stroke ◽

10.1161/str.48.suppl_1.49 ◽

2017 ◽

Vol 48 (suppl_1) ◽

Author(s):

Yejie Shi ◽

Xiaoyan Jiang ◽

Lili Zhang ◽

Hongjian Pu ◽

Wenting Zhang ◽

...

Keyword(s):

Heat Shock ◽

Heat Shock Protein ◽

Blood Brain Barrier ◽

Actin Polymerization ◽

Ischemia Reperfusion ◽

Neurovascular Unit ◽

Heat Shock Protein 27 ◽

Fiber Formation ◽

Brain Barrier ◽

Blood Brain

Introduction: Blood brain barrier (BBB) damage resulting from ischemia/reperfusion (I/R) disrupts the neurovascular unit and leads to poor patient outcomes. We recently discovered that caveolin-1-independent subtle structural aberrations of brain microvascular endothelial cells (BMECs), such as abnormal actin polymerization, stress fiber formation and subsequent junctional protein (JP) disassembly, are a novel mechanism for rapid BBB breach after I/R. Hypothesis: Heat shock protein 27 (HSP27) reduces BBB breakdown after I/R by inhibiting actin polymerization and JP disassembly in BMECs. Methods: Neuron- or EC-specific HSP27-overexpressing mice were subjected to 1 h MCAO and reperfusion. BBB damage, tissue histology, and neurobehavioral performance were assessed up to 35 d after I/R. I/R-induced BBB damage was also simulated in BMEC cultures, where gene manipulations were achieved using lentiviral vectors. Cell-permeable TAT-HSP27 protein was injected i.v. into mice after I/R to rapidly elevate HSP27 in BMECs. Results: Targeted overexpression of HSP27 within ECs—but not neurons—was sufficient to reduce early (1-3 h) and late (24 h) BBB damage after I/R (p<0.01). Mechanistically, HSP27 suppressed I/R-induced actin polymerization, stress fibers, and JP disassembly in BMECs, but independent of its anti-cell death properties. Intracerebral infiltration of neutrophils and macrophages was attenuated in EC-HSP27 mice by 35% and 60%, respectively (n=6, p<0.05) at 48 h after I/R. Infarct size was reduced by 35% at 72 h, and sensorimotor functions (p<0.01, cylinder and corner tests) were improved in EC-HSP27 mice up to 21 d. Post-I/R injection of TAT-HSP27 markedly reduced BBB damage and elicited sustained (up to 35 d) protection against neurological deficits. Conclusions: HSP27 protects against BBB disruption after I/R by inhibiting actin polymerization and JP disassembly in BMECs. HSP27 may be a therapy for ischemic stroke in conjunction with reperfusion.

Download Full-text