Both fragile X syndrome and Rett syndrome are commonly associated with autism spectrum disorders and involve defects in synaptic plasticity. MicroRNA is implicated in synaptic plasticity because fragile X mental retardation protein was recently linked to the microRNA pathway. DNA methylation is also involved in synaptic plasticity since methyl CpG-binding protein 2 (MeCP2) is mutated in patients with Rett syndrome. Here we report that expression of miR-184, a brain-specific microRNA repressed by the binding of MeCP2 to its promoter, is upregulated by the release of MeCP2 after depolarization. The restricted release of MeCP2 from the paternal allele results in paternal allele-specific expression of miR-184. Our finding provides a clue to the link between the microRNA and DNA methylation pathways.

The promoter selectivity of two extracytoplasmic function (ECF) subfamily subunits, E

The RNA polymerase core enzyme of Escherichia coli is composed of 2alpha, 1beta, and 1beta' subunits. Previously we mapped the alpha-alpha, alpha-beta, and alpha-beta' contact sites on the alpha subunit. Here we analyzed the alpha subunit contact sites on the beta subunit by using various experimental approaches: (i) comparison of the proteolytic cleavage map between the unassembled free beta subunit and the alpha2 beta complex; (ii) analysis of the binary complex formation between His6-tagged intact alpha subunit and various truncated beta fragments; and (iii) analysis of the complex formation between the alpha subunit and various His6-tagged beta fragments. The results altogether indicate that two regions of the beta subunit are involved in the full activity of alpha binding, that is, the primary contact site between residues 737 and 904 and the secondary region with assembly control activity downstream from residue 1138. All of the alpha subunit-beta fragment binary complexes identified in this study were found to bind beta' subunit and form pseudo-core complexes, indicating that the regions of beta involved in alpha subunit contact also participate in interaction with the beta' subunit.

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