A protein derived from the fusion of TAT peptide and FNK, a Bcl-x(L) derivative, prevents cochlear hair cell death from aminoglycoside ototoxicity in vivo.
We constructed a powerful artificial cytoprotective protein, FNK, from an antiapoptotic member of the BCL-2 family, Bcl-x(L). To test the efficacy of FNK in protecting cochlear hair cells (HCs) from aminoglycoside-induced cell death in vivo, we fused FNK with protein transduction domain, TAT, of the HIV/Tat protein to construct a fusion protein of TAT-FNK. We demonstrated that, after an intraperitoneal administration to guinea pigs, TAT-myc-FNK protein was diffusely distributed in the cochlea, most prominently in the HCs and supporting cells, followed by the spiral ganglion cells, 3 hr after the injection. We next demonstrated that TAT-FNK attenuated cochlear damage induced by an ototoxic combination of kanamycin sulfate (KM) and ethacrynic acid (EA) administered at 2 different dosages: 400 mg/kg KM + 50 mg/kg EA and 200 mg/kg KM + 40 mg/kg EA. TAT-FNK or vehicle was intraperitoneally injected from 3 hr before through 5 hr after inducing the ototoxic insults, 14 days after which auditory brainstem response (ABR) and HC loss were evaluated. In comparison with vehicle-administered controls, the TAT-FNK protein significantly attenuated ototoxic drug-induced ABR threshold shifts and the extent of HC death at either dosage. The TAT-FNK protein also significantly reduced the amount of cleaved poly-(ADP-ribose) polymerase-positive HCs 8 hr after the ototoxic insults compared with that in the vehicle-administered controls. These findings indicate that systemically administered TAT-FNK was successfully delivered to the guinea pig cochlea and effectively prevented apoptotic cell death of the cochlear HCs induced by KM and EA.
Kashio
Akinori
A
Department of Otolaryngology and Head and Neck Surgery, University of Tokyo, Tokyo, Japan.
Sakamoto
Takashi
T
Suzukawa
Keigo
K
Asoh
Sadamitsu
S
Ohta
Shigeo
S
Yamasoba
Tatsuya
T
D000617:Aminoglycosides; D000704:Analysis of Variance; D000818:Animals; D016923:Cell Death / Q000187:drug effects; D003051:Cochlea / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004976:Ethacrynic Acid; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects / Q000502:physiology*; D015696:Gene Products, tat / Q000235:genetics; D006168:Guinea Pigs; D006198:Hair Cells, Auditory / Q000187:drug effects / Q000378:metabolism*; D034381:Hearing Loss / Q000139:chemically induced / Q000378:metabolism* / Q000517:prevention & control; D007150:Immunohistochemistry; D007612:Kanamycin; D008297:Male; D018696:Neuroprotective Agents / Q000378:metabolism; D010446:Peptide Fragments / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000378:metabolism / Q000494:pharmacology*; D051020:bcl-X Protein / Q000235:genetics
D000617:Aminoglycosides; D015696:Gene Products, tat; D018696:Neuroprotective Agents; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D051020:bcl-X Protein; D007612:Kanamycin; D004976:Ethacrynic Acid