HIV protease inhibitors provide neuroprotection through inhibition of mitochondrial apoptosis in mice
Toshio Hisatomi, Toru Nakazawa, Kousuke Noda, Lama Almulki, Shinsuke Miyahara, Shintaro Nakao, Yasuhiro Ito, Haicheng She, Riichiro Kohno, Norman Michaud, Tatsuro Ishibashi, Ali Hafezi-Moghadam, Andrew D. Badley, Guido Kroemer, Joan W. Miller
Toshio Hisatomi, Toru Nakazawa, Kousuke Noda, Lama Almulki, Shinsuke Miyahara, Shintaro Nakao, Yasuhiro Ito, Haicheng She, Riichiro Kohno, Norman Michaud, Tatsuro Ishibashi, Ali Hafezi-Moghadam, Andrew D. Badley, Guido Kroemer, Joan W. Miller
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Research Article Neuroscience

HIV protease inhibitors provide neuroprotection through inhibition of mitochondrial apoptosis in mice

Abstract

Neuroprotection can be achieved by preventing apoptotic death of postmitotic cells. Apoptotic death can occur by either a caspase-dependent mechanism, involving cytochrome c, apoptosis protease-activating factor–1 (Apaf-1), and caspase-9, or a caspase-independent mechanism, involving apoptosis-inducing factor (AIF). HIV protease inhibitors (PIs) avert apoptosis in part by preventing mitochondrial outer membrane permeabilization (MOMP), but the precise mechanism by which they work is not known. Here, we evaluated the impact of the PIs in a mouse model of retinal detachment (RD) in vivo and in murine primary retinal cell cultures in vitro. Oral administration of the PIs nelfinavir and ritonavir significantly inhibited photoreceptor apoptosis, while preventing the translocation of AIF from mitochondria to the nucleus as well as the activation of caspase-9. RD-induced photoreceptor apoptosis was similarly inhibited in mice carrying hypomorphic mutations of the genes encoding AIF or Apaf-1. Nelfinavir attenuated apoptosis as well as mitochondrial release of AIF and cytochrome c, and subsequent activation of caspase-9 in vitro, in photoreceptor cultures exposed to starvation or monocyte chemoattractant protein–1–stimulated (MCP-1–stimulated) macrophages. Our results suggest that the MOMP inhibition by PIs involved interruption of both caspase-dependent and caspase-independent apoptosis pathways and that PIs may be clinically useful for the treatment of diseases caused by excessive apoptosis.

Authors

Toshio Hisatomi, Toru Nakazawa, Kousuke Noda, Lama Almulki, Shinsuke Miyahara, Shintaro Nakao, Yasuhiro Ito, Haicheng She, Riichiro Kohno, Norman Michaud, Tatsuro Ishibashi, Ali Hafezi-Moghadam, Andrew D. Badley, Guido Kroemer, Joan W. Miller

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Figure 9

PI blocked leakage of proapoptotic molecules from the mitochondria to the cytosol (AIF and cytochrome c) and subsequent activation of caspase-9 in vitro.

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PI blocked leakage of proapoptotic molecules from the mitochondria to th...
Representative images of immunofluorescence detection of AIF (A–F; AIF in red, TUNEL in green) and cleaved activated caspase-9 (G–L; cleaved caspase-9 in red, TUNEL in green) in control photoreceptor cultures (A, B, G, and H) and after starvation in the absence (C, D, I, and J) or presence of NFV (E, F, K, and L). Photoreceptors underwent TUNEL-detectable apoptosis in starvation and macrophage coculture models but were preserved by treatment with NFV (M). AIF translocation and caspase-9 cleavage were also decreased by NFV treatment (M). Immunoblot analyses of cytosolic fractions showed AIF and cytochrome c translocation from the mitochondria to the cytosol and subsequent caspase-9 cleavage under starvation or macrophage cocultures, and these changes were suppressed by NFV treatment (N). n = 10 per group; *P < 0.05, **P < 0.01. Scale bar in A: 1 μm.