Following estrogenic activation, the estrogen receptor-␣ (ER␣) directly regulates the transcription of target genes via DNA binding. MicroRNAs (miRNAs) modulated by ER␣ have the potential to fine tune these regulatory systems and also provide an alternate mechanism that could impact on estrogen-dependent developmental and pathological systems. Through a microarray approach, we identify the subset of microRNAs (miRNAs) modulated by ER␣, which include upregulation of miRNAs derived from the processing of the paralogous primary transcripts (pri-) mir-17-92 and mir-106a-363. Characterization of the mir-17-92 locus confirms that the ER␣ target protein c-MYC binds its promoter in an estrogen-dependent manner. We observe that levels of pri-mir-17-92 increase earlier than the mature miRNAs derived from it, implicating precursor cleavage modulation after transcription. Pri-mir-17-92 is immediately cleaved by DROSHA to pre-miR-18a, indicating that its regulation occurs during the formation of the mature molecule from the precursor. The clinical implications of this novel regulatory system were confirmed by demonstrating that pre-miR-18a was significantly upregulated in ER␣-positive compared to ER␣-negative breast cancers. Mechanistically, miRNAs derived from these paralogous pri-miRNAs (miR-18a, miR-19b, and miR-20b) target and downregulate ER␣, while a subset of pri-miRNA-derived miRNAs inhibit protein translation of the ER␣ transcriptional p160 coactivator, AIB1. Therefore, different subsets of miRNAs identified act as part of a negative autoregulatory feedback loop. We propose that ER␣, c-MYC, and miRNA transcriptional programs invoke a sophisticated network of interactions able to provide the wide range of coordinated cellular responses to estrogen.AIB1 ͉ autoregulatory feedback loop ͉ primary transcript ͉ processing U pon 17-␤-estradiol (E2) binding, estrogen receptors (ERs) mediate transcription by interacting directly to specific estrogen response elements (EREs) located in the promoter/ enhancer region of its target genes or indirectly by tethering to nuclear proteins, such as AP1 and SP1 transcription factors (2-4). The cellular response to estrogen is highly regulated at multiple levels including transcription, RNA stability, and posttranslational modifications (5-8). Following treatment with E2, ER␣ transcription and mRNA stability is substantially reduced within 1 h of stimulation (7). Furthermore, E2-ER␣ interactions accelerate receptor degradation through the ubiquitinproteasome pathway, an effect associated with its major coactivator AIB1 (8).MicroRNAs (miRNAs) are a class of noncoding short RNAs, 21-24 nucleotides (nt) in length, that play a role in gene regulation. They downregulate expression of their target genes by base pairing to the 3Ј-UTR of target messenger RNAs (mRNAs) (9). During their biogenesis most miRNAs are transcribed as part of a longer transcript named pri-miRNA (10). These molecules are processed inside the nucleus by DROSHA, producing a pre-miRNA that is a 70-nt ''imperfect'' stem loop ...

A transfection assay with a lymphoblastoid cell line infected with Epstein-Barr virus was used to compare the abilities of type 1 and type 2 EBNA2 to sustain cell proliferation. The reduced proliferation in cells expressing type 2 EBNA2 correlated with loss of expression of some cell genes that are known to be targets of type 1 EBNA2. Microarray analysis of EBNA2 target genes identified a small number of genes that are more strongly induced by type 1 than by type 2 EBNA2, and one of these genes (CXCR7) was shown to be required for proliferation of lymphoblastoid cell lines. The Epstein-Barr virus LMP1 gene was also more strongly induced by type 1 EBNA2 than by type 2, but this effect was transient. Type 1 and type 2 EBNA2 were equally effective at arresting cell proliferation of Burkitt's lymphoma cell lines lacking Epstein-Barr virus and were also shown to cause apoptosis in these cells. The results indicate that differential gene regulation by EpsteinBarr virus type 1 and type 2 EBNA2 may be the basis for the much weaker B-cell transformation activity of type 2 Epstein-Barr virus strains compared to type 1 strains.

The a-Ca 2 þ /calmodulin-dependent protein kinase II (aCaMKII) is a crucial enzyme controlling plasticity in the brain. The autophosphorylation of aCaMKII works as a 'molecular memory' for a transient calcium activation, thereby accelerating learning. We investigated the role of aCaMKII autophosphorylation in the establishment of alcohol drinking as an addiction-related behavior in mice. We found that alcohol drinking was initially diminished in aCaMKII autophosphorylation-deficient aCaMKII T286A mice, but could be established at wild-type level after repeated withdrawals. The locomotor activating effects of a low-dose alcohol (2 g/kg) were absent in aCaMKII T286A mice, whereas the sedating effects of high-dose (3.5 g/kg) were preserved after acute and subchronic administration. The in vivo microdialysis revealed that aCaMKII T286A mice showed no dopamine (DA) response in the nucleus accumbens to acute or subchronic alcohol administration, but enhanced serotonin (5-HT) responses in the prefrontal cortex. The attenuated DA response in aCaMKII T286A mice was in line with altered c-Fos activation in the ventral tegmental area after acute and subchronic alcohol administration. In order to compare findings in mice with the human condition, we tested 23 single-nucleotide polymorphisms (SNPs) in the CAMK2A gene for their association with alcohol dependence in a population of 1333 male patients with severe alcohol dependence and 939 controls. We found seven significant associations between CAMK2A SNPs and alcohol dependence, one of which in an autophosphorylation-related area of the gene. Together, our data suggest aCaMKII autophosphorylation as a facilitating mechanism in the establishment of alcohol drinking behavior with changing the DA-5-HT balance as a putative mechanism.

Shank3 is a structural protein found predominantly at the postsynaptic density. Mutations in the SHANK3 gene have been associated with risk for autism spectrum disorder (ASD). We generated induced pluripotent stem cells (iPSCs) from control individuals and from human donors with ASD carrying microdeletions of SHANK3. In addition, we used Zinc finger nucleases to generate isogenic SHANK3 knockout human embryonic stem (ES) cell lines. We differentiated pluripotent cells into either cortical or olfactory placodal neurons. We show that patient-derived placodal neurons make fewer synapses than control cells. Moreover, patient-derived cells display a developmental phenotype: young postmitotic neurons have smaller cell bodies, more extensively branched neurites, and reduced motility compared with controls. These phenotypes were mimicked by SHANK3-edited ES cells and rescued by transduction with a Shank3 expression construct. This developmental phenotype is not observed in the same iPSC lines differentiated into cortical neurons. Therefore, we suggest that SHANK3 has a critical role in neuronal morphogenesis in placodal neurons and that early defects are associated with ASD-associated mutations.

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