Skeletal muscle atrophy leads to loss and dysfunction of muscle precursor cells.
ABSTRACT Atrophy of skeletal muscle leads to decreases in myofiber size and nuclear number; however, the effects of atrophic conditions on muscle precursor cells (MPC) are largely unknown. MPC lie outside myofibers and represent the main source of additional myonuclei necessary for muscle growth and repair. In the present study, we examined the properties of MPC after hindlimb suspension (HS)-induced atrophy and subsequent recovery of the mouse hindlimb muscles. We demonstrated that the number of MPC in atrophied muscles was decreased. RT-PCR analysis of cells isolated from atrophied muscles indicated that several mRNA characteristic of the myogenic program in MPC were absent. Cells isolated from atrophied muscles failed to properly proliferate and undergo differentiation into multinucleated myotubes. Thus atrophy led to a decrease in MPC and caused dysfunction in those MPC that remained. Upon regrowth of the atrophied muscles, these deleterious effects were reversed. Our data suggest that preventing loss or dysfunction of MPC may be a new pharmacological target during muscle atrophy.
- Neuroscience and Behavioral Physiology 09/2014; 44(7):817-827.
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ABSTRACT: The present study attempts to develop a comprehensive perspective of the wind regime on the Romanian territory, focusing on the characteristics and tendencies encountered over the past 50 years, as well as on the NAO projection on it, using several data categories gathered from 167 meteorological stations. Based on the recorded multiannual averages and on the strong correlation (r = 0.87) established between altitude and wind speed in wind exposed areas, we created the map of mean (multi)annual wind speed. The highest aeolian potential corresponds to the Carpathians (7-10 m/s on the ridges and 3-7 m/s on the slopes and within valleys) and the Black Sea Shore (5-7 m/s); nevertheless, the two areas develop extreme values of the wind turbulence – maximum in the Carpathians and minimum in the coastal units. Tablelands in Moldova and Dobrogea, as well as the northern part of Bărăgan show ideal conditions for the development of aeolian parks (moderate and strong winds, low turbulences). On a country-size scale, the month with the highest mean wid speed is March, whereas August is the calmest one. For the first time, the map of resultant wind direction (DRV) was designed, expressing both the resultant wind orrientation and its intensity (high intensity = low directional variability). Concerning NAO, a negative correlation is observed between its indices and the wind speed (mean speed, frequency and intensity of the stromic events) at a multiannual and multidecadal scale. The correlation coefficients present high values in the extra-carpathian areas and small or moderate values in the intra-carpathian areas. The positive (negative) NAO associated with low (high) cyclogenesis over the Mediterranean area induce low (high) winds over the Romanian territory due to diminished (enhanced) frequency of cyclones reaching Romanian regions.Forum Geografic. 12/2012; XI(2):118-126.
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ABSTRACT: MicroRNAs (miRNAs) are small, noncoding RNAs that regulate gene expression and, in cancers, are often packaged within secreted microvesicles. The cachexia syndrome is a debilitating state of cancer that predominantly results from the loss of skeletal muscle mass, which is in part associated with apoptosis. How tumors promote apoptosis in distally located skeletal muscles has not been explored. Using both tumor cell lines and patient samples, we show that tumor-derived microvesicles induce apoptosis of skeletal muscle cells. This proapoptotic activity is mediated by a microRNA cargo, miR-21, which signals through the Toll-like 7 receptor (TLR7) on murine myoblasts to promote cell death. Furthermore, tumor microvesicles and miR-21 require c-Jun N-terminal kinase activity to regulate this apoptotic response. Together, these results describe a unique pathway by which tumor cells promote muscle loss, which might provide a great insight into elucidating the causes and treatment options of cancer cachexia.Proceedings of the National Academy of Sciences 03/2014; · 9.81 Impact Factor