The role of p38 in mitochondrial respiration in male and female mice
ABSTRACT p38 is a mitogen-activated protein kinase and mediates cell growth, cell differentiation, and synaptic plasticity. The aim of this study is to determine the extent to which p38 plays a role in maintaining mitochondrial respiration in male and female mice under a normal condition. To achieve this aim, we have generated transgenic mice that lack p38 in cerebellar Purkinje neurons by crossing Pcp2 (Purkinje cell protein 2)-Cre mice with p38(loxP/loxP) mice. Mitochondria from cerebellum were then isolated from the transgenic and wild-type mice to measure mitochondrial respiration using XF24 respirometer. The mRNA and protein expression of cytochrome c oxidase (COX) in cerebellum were also measured using RT-PCR and immunoblot methods. Separately, HT22 cells were used to determine the involvement of 17β-estradiol (E2) and COX in mitochondrial respiration. The genetic knockout of p38 in Purkinje neurons suppressed the mitochondrial respiration only in male mice and increased COX expression only in female mice. The inhibition of COX by sodium azide (SA) sharply suppressed mitochondrial respiration of HT22 cells in a manner that was protected by E2. These data suggest that p38 is required for the mitochondrial respiration of male mice. When p38 is below a normal level, females may maintain mitochondrial respiration through COX up-regulation.
- [Show abstract] [Hide abstract]
ABSTRACT: Salubrinal is a specific eIF2α phosphatase inhibitor that inhibits ER stress-mediated apoptosis. However, maintaining hyper-phosphorylated eIF2α state with high doses of salubrinal treatment promotes apoptosis in some cancer cells. In this report, we found that salubrinal induced apoptosis of EBV-transformed B cells. Notably, salubrinal induced ROS generation and p38 MPAK activation, which then induced expression of FasL. Moreover, salubrinal subsequently led to activation of caspases, calcium redistribution, Bax translocation, cytochrome c release, and apoptosis. These findings suggest that salubrinal may be a novel therapeutic approach for EBV-associated malignant diseases.Cancer letters 09/2011; 313(2):235-48. DOI:10.1016/j.canlet.2011.09.011 · 5.62 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: The mitogen-activated protein kinase (MAP kinase, MAPK) cascade, as the name implies, was originally discovered as a critical regulator of cell division and differentiation. As further details of this signaling cascade were worked out, it became clear that the MAPK cascade is in fact a prototype for a family of signaling cascades that share the motif of three serially linked kinases regulating each other by sequential phosphorylation. Thus, a revised nomenclature arose that uses the term MAPK to refer to the entire superfamily of signaling cascades (comprising the erks, the JNKs and the p38 stress activated protein kinases), and specifies the prototype MAPK as the extracellular signal-regulated kinase (erk). The two erk MAPK isoforms, p44 MAPK and p42 MAPK, are referred to as erk1 and erk2, respectively. The erks are abundantly expressed in neurons in the mature central nervous system, raising the question of why the prototype molecular regulators of cell division and differentiation are present in these non-dividing, terminally differentiated neurons. This review will describe the beginnings of an answer to this question. Interestingly, the general model has begun to emerge that the erk signaling system has been co-opted in mature neurons to function in synaptic plasticity and memory. Moreover, recent insights have led to the intriguing prospect that these molecules serve as biochemical signal integrators and molecular coincidence detectors for coordinating responses to extracellular signals in neurons. In this review I will first outline the essential components of this signal transduction cascade, and briefly describe recent results implicating the erks in mammalian synaptic plasticity and learning. I will then proceed to outline recent results implicating the erks as molecular signal integrators and, potentially, coincidence detectors. Finally, I will speculate on what the critical downstream effectors of the erks are in neurons, and how they might provide a readout of the integrated signal.Journal of Neurochemistry 02/2001; 76(1):1-10. · 4.24 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: We examined rat ovarian granulosa cells at different follicular stages and evaluated the apoptosis pattern of the mitochondria-dependent genes during folliculogenesis. After down-regulating ovarian function with gonadotropin-releasing hormone agonist (GnRHa), granulosa cells were collected from the rat ovary at different stages of the following different hormonal treatment paradigms: stage E (after estrogen treatment), EF (after E + follicle-stimulating hormone [FSH] treatment), and EF hCG (after E + FSH + human chorionic gonadotropin treatment). To evaluate the in vitro susceptibility of granulosa cells at different developmental stages to apoptosis, the collected cells were cultured in a serum-free medium with or without E2 for 24 hours. The regulation of apoptosis in the granulosa cells was analyzed using fluorescein-activated cell sorting, quantitative competitive polymerase chain reaction, and western blot methods. The apoptosis rate of the freshly isolated granulosa cells tended to increase according to the hormonal treatment paradigm. In addition, during the hormone treatment, mitochondria-dependent apoptosis genes showed the following changes: although the Bax mRNA level did not change, the Bcl-2 mRNA level decreased significantly (P <.05). The p53 mRNA level increased significantly (P <.05) and closely matched the apoptosis rate (R = 0.7, P <.05). The expression of the active form of the caspase-3 protein (the final executioner of cell death) tended to increase and showed a good correlation with the apoptosis rate (R = 0.96, P <.01). After an in vitro culture of the granulosa cells, the apoptosis rate tended to increase at all stages, particularly stage EF hCG (P <.05). Bax and p53 mRNA tended to increase and showed a good correlation with the apoptosis rate (R = 0.64, P <.05 and 0.86, P <.01). The Bcl-2 mRNA level tended to decrease at all stages showing no correlation with the apoptosis rate. The expression level of the active caspase-3 protein tended to increase at all stages and showed a good correlation with the apoptosis rate (R = 0.93, P <.01). Apoptosis of rat ovarian granulosa cells tends to increase according to the stage of follicular development. Among the mitochondria-dependent genes, p53 closely correlates with granulosa cell apoptosis during follicular development.Journal of the Society for Gynecologic Investigation 07/2004; 11(5):311-7. DOI:10.1016/j.jsgi.2004.01.015 · 2.33 Impact Factor