NEUROPROTECTIVE EFFECT OF FK506 AGAINST OXIDATIVE STRESS

ROSBACO, M.E., DANERI-BECERRA, LOTUFO, C.M, GALIGNIANA M.D., RAMOS-HRYB, A.B

MEDICINA (BUENOS AIRES)

MEDICINA (BUENOS AIRES)

Año: 2019 vol. 79

0025-7680

Immunophilins are proteins that bind immunosuppressive drugs. Those that bind cyclosporin A (CsA) are cyclophilins (ej, CyPA), and those that recognize the macrolide FK506 are FKBPs (FK506-Binding Proteins), a subfamily to which FKBP51 (51-kDa) and FKBP52 (52 -kDa). Both FKBPs were described in steroidal receptor heterocomplexes with Hsp90, Hsp70 and p23. FKBP51 and FKBP52 have 60% similarity and 75% homology. Previous laboratory studies showed that FK506 has regulatory effects on neurodifferentiation through both FKBPs, such that overexpression of FKBP52 or silencing of FKBP51 promoted neuritogenesis.Similarly, the axonal damage of the cells was reversed with FK506, being accelerated when overexpressed to FKBP52 or by knock-down of FKBP51. This suggests that these immunophilins could have neuroprotective or neuroregenerative actions in adverse situations such as, for example, oxidative stress associated with neurodegenerative diseases, cerebrovascular accidents or neuronal overexcitation. In this study, it was analyzed whether treatments with FK506 can prevent and / or reverse the deleterious effects associated with oxidative stress of H2O2. Undifferentiated N2a (murine neuroblastoma) cells were incubated in DMEM / OptiMEM medium (without serum) with 1 µM FK506, observing the rapid generation of neurites. 250 µm thick sections obtained from prefrontal cortex of male Balb / C mice (60 d) were incubated in special medium on 4% agar. After 72 hours of tissue stabilization, the explants were incubated for 4 hours with 200 µM H2O2. The induction of Hsp90, Hsp70, FKBP52 and p23 was evidenced, which was prevented by pretreatment (1h) with 1 M FK506. Regarding FKBP51, the controls showed three bands corresponding to their known phosphorylated isoforms, while explants treated with H2O2 showed only the least phosphorylated band. Pretreatment with FK506 protected phosphorylated isoforms, showing the same pattern of isoforms as the control. In turn, the samples treated with FK506 showed only the intermediate phosphorylated band, suggesting that this isoform (reactive with anti-P-Tyr antibodies) is favored in the mechanism of action of the drug.To show effects in vivo, relative hypoxia was generated by stereotactic injection of 2 l 50 mM CoCl2 in the prefrontal cortex of the right hemisphere, using the contralateral as a control. Chaperone expression was induced in tissue lysates obtained 24 h later, which was partially prevented by pretreatment (24 h) with 10 g / kg FK506. The effects on motor balance were studied after 21 days (FK506 injected every 3 days) by Rotarod and open field (Anymaze), observing a better and faster recovery in mice treated with FK506. This is the first study that shows a neuroprotective effect of FK506 against oxidative stress.