RESUMEN
Heat shock protein 70 (HSP70) is activated under stress response. Its involvement in cell protection, including energy metabolism and quality control makes it a promising pharmacological target. A strategy to increase HSP70 levels inside the cells is the application of recombinant HSP70. However, cell permeability and functionality of these exogenously applied proteins inside the cells is still disputable. Here, using fluorescence- labeled HSP70, we have studied permeability and distribution of HSP70 inside primary neurons and astrocytes, and how exogenous HSP70 changes mitochondrial metabolism and mitophagy. We have found that exogenous recombinant HSP70 can penetrate the neurons and astrocytes and distributes in mitochondria, lysosomes and in lesser degree in the endoplasmic reticulum. HSP70 increases mitochondrial membrane potential in control neurons and astrocytes, and in fibroblasts of patients with familial Parkinson´s disease (PD) with PINK1 and LRRK2 mutations. Increased mitochondrial membrane potential was associated with higher mitochondrial ROS production and activation of mitophagy. Importantly, preincubation of the cells with HSP70 protected neurons and astrocytes against cell death in a toxic model of PD induced by rotenone, and in the PINK1 and LRRK2 PD human fibroblasts. Thus, exogenous recombinant HSP70 is cell permeable, and acts as endogenous HSP70 protecting cells in the case of toxic model and familial forms of Parkinson's Disease.
RESUMEN
Hsp70 is the main molecular chaperone responsible for cellular proteostasis under normal conditions and for restoring the conformation or utilization of proteins damaged by stress. Increased expression of endogenous Hsp70 or administration of exogenous Hsp70 is known to exert neuroprotective effects in models of many neurodegenerative diseases. In this study, we have investigated the effect of exogenous Hsp70 on recovery from peripheral nerve injury in a model of sciatic nerve transection in rats. It was shown that recombinant Hsp70 after being added to the conduit connecting the ends of the nerve at the site of its extended severance, migrates along the nerve into the spinal ganglion and is retained there at least three days. In animals with the addition of recombinant Hsp70 to the conduit, a decrease in apoptosis in the spinal ganglion cells after nerve rupture, an increase in the level of PTEN-induced kinase 1 (PINK1), an increase in markers of nerve tissue regeneration and a decrease in functional deficit were observed compared to control animals. The obtained data indicate the possibility of using recombinant Hsp70 preparations to accelerate the recovery of patients after neurotrauma.
