In addition to the above mechanism, we present evidence for a new layer of Rapamycin repression through recruitment of YY1/Ezh2 repressive complex on multiple sites of miR-29 promoter. Given that three of the four YY1 binding sites, Y2, Y3, and Y6, are not adjacent to SBEs, it is very likely that the recruitment is independent on Smad3 binding. Nevertheless, one of the identified YY1 sites, Y1, was very close to a SBE, S1, suggesting that additional mechanism dependent on Smad3 binding may exist. Further studies are needed to test the above hypotheses. Therefore, the above two modes of actions exert reinforcing levels of control on miR-29 transcription, ensuring its down-regulation during the fibrogenic differentiation of myoblasts. The application of this new mechanism may extend beyond miR-29 promoter and represent a general mode of TGF-b/Smad3 repression in skeletal muscle differentiation considering many myofibrillar genes were also regulated by MyoD and YY1/Ezh2 complex. Together with others�� findings, our data suggest that diverse mechanisms lead to transcriptional repression in response to TGF-b. Taken together, our results identified miR-29 as a pleiotropic molecule in muscle cells. As modeled in Figure 6, during normal muscle regeneration, miR-29 level is elevated through replacing a repressive YY1/Ezh2/HDAC1 complex by a MyoD/SRF activating complex on its promoter, leading to successful myogenic differentiation ; However, during the transdifferentiation, activated TGF-b signaling induces Smad3 translocation into nucleus where it binds to miR-29 promoter, resulting in MyoD dissociation as well as YY1/Ezh2 stabilization. This causes a loss of miR-29 expression and increased expression of Collagens and Lims1, leading to the transdifferentiation of myoblasts into myofibroblasts. Capacitation and acrosomal exocytosis are processes required for sperm to fertilize the oocyte in vivo. A number of changes occur at the sperm surface during sperm capacitation. These capacitation-induced surface changes are effectuated in vitro by two capacitation factors, namely bicarbonate and fatty acid free bovine serum albumin. In the presence of calcium, both factors activate protein kinase A and tyrosine kinase signaling pathways that lead to the hypermotility of sperm cells and the specific depletion of cholesterol from the sperm surface. The depletion of cholesterol from the sperm plasma membrane allows the rearrangement of proteins and lipids and leads to an increase in membrane fluidity. Furthermore, a change in the influx and efflux of essential ions through the activated ion channels alter the membrane potential and this activates Tubacin relevant processes that are required for the execution of AE. Under physiological conditions, the PM from capacitated sperm remains intact for an extended period and will not undergo a spontaneous fusion with the underlying outer acrosome membrane unless an additional AE inducer is present.