PEX11alpha is required for peroxisome proliferation in response to 4-phenylbutyrate but is dispensable for peroxisome proliferator-activated receptor alpha-mediated peroxisome proliferation.

The PEX11 peroxisomal membrane proteins promote peroxisome division in multiple eukaryotes. As part of our effort to understand the molecular and physiological functions of PEX11 proteins, we disrupted the mouse PEX11alpha gene. Overexpression of PEX11alpha is sufficient to promote peroxisome division, and a class of chemicals known as peroxisome proliferating agents (PPAs) induce the expression of PEX11alpha and promote peroxisome division. These observations led to the hypothesis that PPAs induce peroxisome abundance by enhancing PEX11alpha expression. The phenotypes of PEX11alpha(-/-) mice indicate that this hypothesis remains valid for a novel class of PPAs that act independently of peroxisome proliferator-activated receptor alpha (PPARalpha) but is not valid for the classical PPAs that act as activators of PPARalpha. Furthermore, we find that PEX11alpha(-/-) mice have normal peroxisome abundance and that cells lacking both PEX11alpha and PEX11beta, a second mammalian PEX11 gene, have no greater defect in peroxisome abundance than do cells lacking only PEX11beta. Finally, we report the identification of a third mammalian PEX11 gene, PEX11gamma, and show that it too encodes a peroxisomal protein.

[Effects of NBP on ATPase and anti-oxidant enzymes activities and lipid peroxidation in transient focal cerebral ischemic rats].

OBJECTIVE: The aim of the present study was designed to explore the effect of (+/-) -3-n-butylphthalide (NBP) on ATPase, anti-oxidant enzymes activities and lipid peroxidation of mitochondria and cerebral cortex in rats subjected to 24 hours of reperfusion following 2 hours of cerebral ischemia (tMCAO). METHODS: Activities of SOD (Superoxide Dismutase), GSH-Px (glutathione Peroxidase,) and CAT (Catalase), and MDA level of mitochondria or cortex were measured by using biochemical methods in tMCAO rats. RESULTS: (1) The activities of mitochondrial Na+K(+)-ATPase, Ca(2+)-ATPase and Mg2+ ATPase were found to decrease significantly in the vehicle group (ischemia + saline). Pre-treatment with NBP (5, 10, 20 mg/kg, i.p.) 10 min before tMCAO markedly enhanced the activities of Na+K(+)-ATPase and Ca(2+)-ATPase, compared with vehicle group. (2) The activities of SOD and mitochondrial GSH-Px were decreased and MDA level increased in vehicle groups as compared with that in sham group (non-ischemia + saline). NBP (20 mg/kg, i.p.) significantly enhanced total mitochondrial SOD activity, and also enhanced cerebral cortex total SOD activity (in 5, 10, 20 mg/kg groups). However, it had no obvious effect on CuZn-SOD activity. NBP (20 mg/kg i.p.) markedly increased mitochondrial (but not in cerebral cortex) GSH-Px activity; NBP 10, 20 mg/kg markedly decreased mitochondrial MDA level compared with that in vehicle group (P < 0.05). (3) The action of raceme NBP on the increase of the activities of ATPase and antioxidative enzymes seemed to be beneficial than that of (-) -NBP or (+) NBP. CONCLUSION: The results suggest that NBP improves energy pump and subsides oxidative injury which may contribute to its anti-neuronal apoptotic effect.