Extracellular-regulated kinase and p38 mitogen-activated protein kinases are involved in the antiapoptotic action of 17β-estradiol in skeletal muscle cells

Abstract

17b-Estradiol (E 2 ) stimulates the mitogen-activated protein kinases (MAPKs) in various cellular types. We have shown that the hormone activates extracellular-regulated kinase (ERK) and p38 MAPK in skeletal muscle cells. However, the functions of MAPK modulation by the estrogen in muscle cells have not been studied yet. We have recently reported antiapoptotic actions of E 2 in C2C12 cells. Here, the role of MAPKs mediating the hormone effect in muscle cells was investigated. The results showed that cells exposed to 0 . 5 mM hydrogen peroxide (H 2 O 2 ) presented cytoskeleton disorganization, mitochondrial redistribution, and picnotic/ fragmented nuclei. Pretreatment with 10K8 M E 2 prevented these morphological apoptotic characteristics, except in the presence of ERK or p38 MAPK inhibitors, U0126 and SB203580 respectively. Mitochondrial membrane integrity was also studied. Preincubation of cultures with 10 K8 M E 2 abrogated H 2 O 2 effects such as Janus Green oxidation, presence of cytochrome c oxidase activity in the cytoplasm, and SMAC/DIABLO release from mitochondria. When MAPKs were inhibited, the hormone could not prevent mitochondrial membrane damage exerted by oxidative stress. Blocking experiments with small interfering RNAs confirmed that both ERK and p38 MAPKs mediate the antiapoptotic effects of the hormone at the mitochondrial level. Further, some of the molecular mechanisms involved were also investigated. Thus, E 2 was able to induce AKT (Ser473) and BAD (Ser112) phosphorylation in C2C12 cells in the absence or in the presence of H 2 O 2 but not when the cultures were incubated with H 2 O 2 and MAPK inhibitors. Altogether, these results show that E 2 exerts a survival action in skeletal muscle cells involving ERK and p38 MAPK activation.

Estradiol exerts antiapoptotic effects in skeletal myoblasts via mitochondrial PTP and MnSOD

“…These results are in general agreement with data previously obtained using Janus Green stain, an indicator of the status of the oxido-reduction mitochondrial system (Lazarow & Cooperstein 1953, Ernster & Schatz 1981, Ronda et al 2010. …”

“…Typical changes of apoptosis such as nuclear fragmentation, cytoskeleton disorganization, mitochondrial reorganization/dysfunction, and cytochrome c release induced by H 2 O 2 , were abolished when cells were previously exposed to E 2 (Vasconsuelo et al 2008). Likewise, we demonstrated that E 2 exerts its antiapoptotic effect through ERs with non-classical localization involving MAPKs, HSP27, and the survival PI3K/Akt pathway, which phosphorylates and inactivates proapoptotic members of the Bcl-2 family (Vasconsuelo et al 2008, Ronda et al 2010. The mitochondrial protein cytochrome c plays a key role in apoptosis (reviewed by Jiang & Wang (2004)).…”

“…In previous studies, we showed that E 2 abrogates H 2 O 2 -induced apoptosis in skeletal muscle cells involving both ERa and ERb, PI3K/Akt/Bad, HSP27, and MAPKs (Vasconsuelo et al 2008, Ronda et al 2010). Accordingly, a protective effect of the steroid on mitochondria integrity was evidenced, as cytochrome c release by H 2 O 2 was inhibited by E 2 through ERb (Vasconsuelo et al 2008).…”

17�-Estradiol Protects Mitochondrial Functions through Extracellular-Signal-Regulated Kinase in C2C12 Muscle Cells

“…We have previously demonstrated that E2 exerts a protective effect against H 2 O 2 -induced apoptosis in C2C12 murine skeletal myoblasts. Specifically we observed an antiapoptotic action of the hormone through ERs with non classical localization involving PI3K/Akt/Bad, HSP27 and MAPKs [9,10,11]. MAPKs are activated by phosphorylation via different upstream MAPK kinases (MKKs or MEKs) which in turn are upregulated by the MAPK kinase kinases or MEKKs [12].…”

“…Certainly it has been shown that a fraction of ERK1/2 is targeted to mitochondria where it modulates specific functions of the organelle [14,15]. Since MAPKs are involved in the antiapoptotic effects of E2 in skeletal myoblastic cells, and although it has been also observed that the hormone protects mitochondrial membrane integrity through an ERK and p38 MAPK-dependent mechanism [11], additional aspects of the role and localization of MAPKs during the estrogen effect in myoblasts need to be elucidated.…”