HIV protease inhibitors provide neuroprotection through inhibition of mitochondrial apoptosis in mice
Toshio Hisatomi, … , Guido Kroemer, Joan W. Miller
Toshio Hisatomi, … , Guido Kroemer, Joan W. Miller
Published May 22, 2008
Citation Information: J Clin Invest. 2008;118(6):2025-2038. https://doi.org/10.1172/JCI34267.
View: Text | PDF
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

×

Figure 3

AIF deficiency protects from RD-induced photoreceptor apoptosis.

Options: View larger image (or click on image) Download as PowerPoint
AIF deficiency protects from RD-induced photoreceptor apoptosis. To exam...
To examine the AIF expression in retinas of AIF mutant mice (Hq/Y), we compared the expression of AIF and AIFsh mRNA (A and B) and AIF protein (C) in WT and Hq/Y mice before and after RD. Hq/Y mice exhibited negligible levels of AIF mRNA or AIF protein in contrast to WT mice (A–C). We also examined the expression of AIFsh, a proapoptotic short variant of AIF. The AIFsh mRNA expression was also decreased in AIF-deficient mice (Hq/Y;A and B), and AIFsh protein expression was not induced by RD in WT or Hq/Y mice (C). AIF immunohistochemistry confirmed the low AIF expression in Hq/Y mice (G and H; AIF in red, TUNEL in green, DAPI in blue) in contrast to WT mice (D and E). AIF deficiency in Hq/Y mice substantially decreased TUNEL-positive apoptotic cells after RD (E, H, and J) and preserved ONL cell count (K) and ONL thickness (L). The remaining TUNEL-positive apoptotic photoreceptors showed activated, cleaved caspase-9 in Hq/Y mice (F and I, caspase-9 in red). Electron microscopy also showed well-preserved rod spherules and cone pedicles in the outer plexiform layer (M and P, arrowheads; degenerated pedicles and spherules), decreased apoptotic nuclei in the ONL (N and Q, arrows), and relatively preserved mitochondria in the inner segment of photoreceptors (O and R, white arrows). n = 5 per group; *P < 0.05, **P < 0.01. Scale bars: 50 μm (D), 10 μm (M).