Testosterone induces up-regulation of mitochondrial gene expression in murine C2C12 skeletal muscle cells accompanied by an increase of nuclear respiratory factor-1 and its downstream effectors.

The reduction in muscle mass and strength with age, sarcopenia, is a prevalent condition among the elderly, linked to skeletal muscle dysfunction and cell apoptosis. We demonstrated that testosterone protects against HO-induced apoptosis in C2C12 muscle cells. Here, we analyzed the effect of testosterone on mitochondrial gene expression in C2C12 skeletal muscle cells.

Adverse Effects in Skeletal Muscle Following the Medicinal Use of Nicotiana glauca.

Nicotiana glauca is a cosmopolitan shrub, used in medicine to treat swellings, wounds, sores and cancer. However, its users lack of knowledge of the adverse effects. We seek to evaluate the effects of lipid extracts from N.

Testosterone modulates FoxO3a and p53-related genes to protect C2C12 skeletal muscle cells against apoptosis.

The loss of muscle mass and strength with aging, sarcopenia, is a prevalent condition among the elderly, associated with skeletal muscle dysfunction and enhanced muscle cell apoptosis. We have previously demonstrated that testosterone protects against HO-induced apoptosis in C2C12 muscle cells, at different levels: morphological, biochemical and molecular. Since we have observed that testosterone reduces p-p53 and maintains the inactive state of FoxO3a transcription factor, induced by HO, we analyzed if the hormone was exerting its antiapoptotic effect at transcriptional level, by modulating pro and antiapoptotic genes associated to them.

17β-Estradiol Protects Skeletal Myoblasts From Apoptosis Through p53, Bcl-2, and FoxO Families.

17β-Estradiol (E ) protects several nonreproductive tissues from apoptosis, including skeletal muscle. Previously, we showed that E at physiological concentrations prevented apoptosis induced by H O in skeletal myoblasts, reverting PKCδ, JNK, and p66Shc activation and exerting a beneficial action over mitochondria. Since genomic actions underlying the regulation of nuclear gene transcription are a common property of this steroid, the present work characterizes the transcriptional activity modulated by E to exert its antiapoptotic effect.

Effect of testosterone on the regulation of p53 and p66Shc during oxidative stress damage in C2C12 cells.

Accumulating evidence indicates that apoptosis is activated in the aged skeletal muscle, contributing to sarcopenia. We have previously demonstrated that testosterone protects against hydrogen peroxide (H2O2)-induced apoptosis in C2C12 muscle cells, at different levels: morphological, physiological, biochemical and molecular. In the present study we observed that H2O2 induces the mitochondrial permeability transition pore (mPTP) opening and exerts p53 activation in a time-dependent way, with a maximum response after 1-2h of treatment.

17β-Estradiol and testosterone in sarcopenia: Role of satellite cells.

The loss of muscle mass and strength with aging, referred to as sarcopenia, is a prevalent condition among the elderly. Although the molecular mechanisms underlying sarcopenia are unclear, evidence suggests that an age-related acceleration of myocyte loss via apoptosis might be responsible for muscle perfomance decline. Interestingly, sarcopenia has been associated to a deficit of sex hormones which decrease upon aging.

High passage numbers induce resistance to apoptosis in C2C12 muscle cells.

Cell lines with high passage numbers exhibit alterations in cell morphology and functions. In the present work, C2C12 skeletal muscle cells with either low (< 20) or high (> 60) passage numbers (identified as 1-C2C12 or h-C2C12, respectively) were used to investigate the apoptotic response to H2O2 as a function of culture age h-C2C12. We found that older cultures (h-C2C12 group) were depleted of mitochondrial DNA (mtDNA).

Actions of 17β-estradiol and testosterone in the mitochondria and their implications in aging.

A decline in the mitochondrial functions and aging are two closely related processes. The presence of estrogen and androgen receptors and hormone-responsive elements in the mitochondria represents the starting point for the investigation of the effects of 17β-estradiol and testosterone on the mitochondrial functions and their relationships with aging. Both steroids trigger a complex molecular mechanism that involves crosstalk between the mitochondria, nucleus, and plasma membrane, and the cytoskeleton plays a key role in these interactions.

Non-classical localization of androgen receptor in the C2C12 skeletal muscle cell line.

The classical model of testosterone action has been traditionally described as being mediated by the androgen receptor (AR) localized exclusively in the nucleus. However, there is increasing functional evidence for extranuclear localization of AR. We present biochemical and immunological data supporting mitochondrial and microsomal localization of AR in the C2C12 skeletal muscle cell line.

Testosterone exerts antiapoptotic effects against H2O2 in C2C12 skeletal muscle cells through the apoptotic intrinsic pathway.

Experimental data indicate that apoptosis is activated in the aged skeletal muscle, contributing to sarcopenia. We have previously demonstrated that testosterone protects against hydrogen peroxide (H(2)O(2))-induced apoptosis in C2C12 muscle cells. Here we identified molecular events involved in the antiapoptotic effect of testosterone.

Role of 17β-estradiol and testosterone in apoptosis.

17β-Estradiol (E2) and Testosterone (T) exert actions in most animal tissues, in addition to the reproductive system. Thus, both sex steroid hormones affect growth and different cell functions in several organs. Accordingly, the nuclear estrogen (ER) and androgen (AR) receptors are ubiquitously expressed.

Participation of HSP27 in the antiapoptotic action of 17beta-estradiol in skeletal muscle cells.

Exposure to 17beta-estradiol prior to induction of apoptosis protects skeletal muscle cells against damage. The mechanism involved in this protective action of the hormone is poorly understood. In the present study, using the murine muscle cell line C2C12, evidence was obtained that inhibition of H(2)O(2)-induced apoptosis by the estrogen requires the participation of heat shock protein 27 (HSP27).

Expression and subcellular distribution of native estrogen receptor beta in murine C2C12 cells and skeletal muscle tissue.

We have recently described the expression and intracellular localization of ER alpha in murine C2C12 cells and skeletal muscle tissue. In separate studies, a protective role of 17beta-estradiol against apoptosis exerted mainly at the mitochondrial level was also shown in the C2C12 muscle cell line. However, this functional evidence was in accordance with the participation of ER beta.

Expression and localization of estrogen receptor alpha in the C2C12 murine skeletal muscle cell line.

The classical model of 17beta-estradiol action has been traditionally described to be mediated by the estrogen receptor (ER) localized exclusively in the nucleus. However, there is increasing functional evidence for extra nuclear localization of ER. We present biochemical, immunological and molecular data supporting mitochondrial-microsomal localization of ER alpha in the C2C12 skeletal muscle cell line.

17beta-estradiol signaling in skeletal muscle cells and its relationship to apoptosis.

17beta-estradiol exerts an antiapoptotic action in skeletal muscle cells through extranuclear ERalpha and beta. This protective action, mainly involves a non-genomic mechanism of ERK1/2 and PI3K/Akt activation and BAD phosphorylation. ERbeta plays a major role in the inhibition of apoptosis by 17beta-estradiol at the level of mitochondria, whereas ERalpha and ERbeta mediate the activation of Akt to the same extent, suggesting differential involvement of ER isoforms depending on the step of the apoptotic/survival pathway involved.

17Beta-estradiol abrogates apoptosis in murine skeletal muscle cells through estrogen receptors: role of the phosphatidylinositol 3-kinase/Akt pathway.

Estrogens can regulate apoptosis in various cellular systems. The present study shows that 17beta-estradiol (E2), at physiological concentrations, abrogates DNA damage, poly (ADP-ribose) polymerase cleavage, and mitochondrial cytochrome c release induced by H2O2 or etoposide in mouse skeletal muscle C2C12 cells. This protective action, which involved PI3K/Akt activation and Bcl-2 associated death agonist (BAD) phosphorylation, was inhibited by antibodies against the estrogen receptor (ER) alpha or beta isoforms, or transfecting siRNA specific for each isoform.