Eukaryotic gene expression is commonly controlled at the level of RNA polymerase II (RNAPII) pausing subsequent to transcription initiation. Transcription elongation is stimulated by the positive ...transcription elongation factor b (P-TEFb) kinase, which is suppressed within the 7SK small nuclear ribonucleoprotein (7SK snRNP). However, the biogenesis and functional significance of 7SK snRNP remain poorly understood. Here, we report that LARP7, BCDIN3, and the noncoding 7SK small nuclear RNA (7SK) are vital for the formation and stability of a cell stress-resistant core 7SK snRNP. Our functional studies demonstrate that 7SK snRNP is not only critical for controlling transcription elongation, but also for regulating alternative splicing of pre-mRNAs. Using a transient expression splicing assay, we find that 7SK snRNP disintegration promotes inclusion of an alternative exon via the increased occupancy of P-TEFb, Ser2-phosphorylated (Ser2-P) RNAPII, and the splicing factor SF2/ASF at the minigene. Importantly, knockdown of larp7 or bcdin3 orthologues in zebrafish embryos destabilizes 7SK and causes severe developmental defects and aberrant splicing of analyzed transcripts. These findings reveal a key role for P-TEFb in coupling transcription elongation with alternative splicing, and suggest that maintaining core 7SK snRNP is essential for vertebrate development.
We aimed to evaluate the efficacy of an enhanced mindfulness-based stress reduction (MBSR+) vs stress management for headache (SMH). We performed a randomized, assessor-blind, clinical trial of 98 ...adults with episodic migraine recruited at a single academic center comparing MBSR+ (n = 50) with SMH (n = 48). MBSR+ and SMH were delivered weekly by group for 8 weeks, then biweekly for another 8 weeks. The primary clinical outcome was reduction in headache days from baseline to 20 weeks. Magnetic resonance imaging (MRI) outcomes included activity of left dorsolateral prefrontal cortex (DLPFC) and cognitive task network during cognitive challenge, resting state connectivity of right dorsal anterior insula to DLPFC and cognitive task network, and gray matter volume of DLPFC, dorsal anterior insula, and anterior midcingulate. Secondary outcomes were headache-related disability, pain severity, response to treatment, migraine days, and MRI whole-brain analyses. Reduction in headache days from baseline to 20 weeks was greater for MBSR+ (7.8 95% CI, 6.9-8.8 to 4.6 95% CI, 3.7-5.6) than for SMH (7.7 95% CI 6.7-8.7 to 6.0 95% CI, 4.9-7.0) (P = 0.04). Fifty-two percent of the MBSR+ group showed a response to treatment (50% reduction in headache days) compared with 23% in the SMH group (P = 0.004). Reduction in headache-related disability was greater for MBSR+ (59.6 95% CI, 57.9-61.3 to 54.6 95% CI, 52.9-56.4) than SMH (59.6 95% CI, 57.7-61.5 to 57.5 95% CI, 55.5-59.4) (P = 0.02). There were no differences in clinical outcomes at 52 weeks or MRI outcomes at 20 weeks, although changes related to cognitive networks with MBSR+ were observed. Enhanced mindfulness-based stress reduction is an effective treatment option for episodic migraine.
Numerous studies have looked at the effects of histone deacetylase inhibitors (HDACis) on HIV reactivation in established transformed cell lines and primary CD4+ T cells. However, their findings ...remain confusing, and differences between effects of class I- and class II-specific HDACis persist. Because no clear picture emerged, we decided to determine how HDACis reactivate HIV in transformed cell lines and primary cells. We found that neither histone H3 nor tubulin acetylation correlated with HIV reactivation in Jurkat and HeLa cells. Rather, HDACis that could reactivate HIV in chromatin or on episomal plasmids also released free positive transcription elongation factor b (P-TEFb) from its inhibitory 7SK snRNP. In resting primary CD4+ T cells, where levels of P-TEFb are vanishingly low, the most potent HDACi, suberoylanilide hydroxyamic acid (SAHA), had minimal effects. In contrast, when these cells were treated with a PKC agonist, bryostatin 1, which increased levels of P-TEFb, then SAHA once again reactivated HIV. We conclude that HDACis, which can reactivate HIV, work via the release of free P-TEFb from the 7SK snRNP.
Background: HDACis activate HIV transcription.
Results: P-TEFb release from 7SK snRNP correlates better than histone H3 or tubulin acetylation with HIV reactivation by HDACis in cell lines.
Conclusion: Levels of P-TEFb must be increased before HDACis can reactivate HIV in resting primary CD4+ T cells.
Significance: Levels and activity of P-TEFb are critical for HIV reactivation in all cells.
Background
Migraine is comorbid with obesity. Recent research suggests an association between migraine and adipocytokines, proteins that are predominantly secreted from adipose tissue and which ...participate in energy homeostasis and inflammatory processes.
Objectives
In this review, we first briefly discuss the association between migraine and obesity and the importance of adipose tissue as a neuroendocrine organ. We then present a systematic review of the extant literature evaluating circulating levels of adiponectin and leptin in those with migraine.
Methods
A search of the PubMed database was conducted using the keywords “migraine,” “adiponectin,” and “leptin.” In addition reference lists of relevant articles were reviewed for possible inclusion. English language studies published between 2005 and 2015 evaluating circulating blood concentration of adiponectin or leptin in those with migraine were included.
Conclusions
While the existing data are suggestive that adipokines may be associated with migraine, substantial study design differences and conflicting results limit definitive conclusions. Future research utilizing carefully considered designs and methodology is warranted. In particular careful and systematic characterization of pain states at the time of samples, as well as systematic consideration of demographic (eg, age, sex) and other vital covariates (eg, obesity status, lipids) are needed to determine if adipokines play a role in migraine pathophysiology and if any adipokine represents a viable, novel migraine biomarker, or drug target.
Transcriptional cyclin-dependent kinases play important roles in eukaryotic gene expression. CDK7, CDK9 (P-TEFb), and CDK13 are also critical for HIV replication. However, the function of CDK11 ...remained enigmatic. In this report, we determined that CDK11 regulates the cleavage and polyadenylation (CPA) of all viral transcripts. CDK11 was found associated with the TREX/THOC, which recruited this kinase to DNA. Once at the viral genome, CDK11 phosphorylated serines at position 2 in the CTD of RNAPII, which increased levels of CPA factors at the HIV 3′ end. In its absence, cleavage of viral transcripts was greatly attenuated. In contrast, higher levels of CDK11 increased the length of HIV poly(A) tails and the stability of mature viral transcripts. We conclude that CDK11 plays a critical role for the cotranscriptional processing of all HIV mRNA species.
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•The cyclin-dependent kinase CDK11 increases HIV gene expression as part of TREX/THOC•CDK11 is recruited by TREX/THOC to elongating RNAPII and phosphorylates its CTD•RNAPII phosphorylation by CDK11 promotes cleavage and polyadenylation factor recruitment•CDK11 regulates proper 3′ end processing of HIV for optimal viral gene expression
The role of the transcriptional cyclin-dependent kinase CDK11 in HIV replication is unclear. Pak et al. report that CDK11 functions in the transcription/export and THO complex (TREX/THOC) to phosphorylate RNAPII and promote assembly of cleavage and polyadenylation factors at the HIV 3′ end, which ensures optimal HIV gene expression.
Promoter-proximal pausing of RNAPII coincides with the formation of the cap structure at the 5′ end of pre-mRNA, which is bound by the cap-binding protein complex (CBC). Although the positive ...transcription elongation factor b (P-TEFb) stimulates the release of RNAPII from pausing and promotes transcription elongation and alternative splicing by phosphorylating the RNAPII C-terminal domain at Ser2 (S2-P RNAPII), it is unknown whether CBC facilitates these events. In this study, we report that CBC interacts with P-TEFb and transcriptionally engaged RNAPII and is globally required for optimal levels of S2-P RNAPII. Quantitative nascent RNA immunoprecipitation and ChIP experiments reveal that depletion of CBC attenuates HIV-1 Tat transactivation and impedes transcription elongation of investigated CBC-dependent endogenous genes by decreasing the levels of P-TEFb and S2-P RNAPII, leading to accumulation of RNAPII in the body of these genes. Finally, CBC is essential for the promotion of alternative splicing through facilitating P-TEFb, S2-P RNAPII, and splicing factor 2/alternative splicing factor occupancy at a splicing minigene. These findings disclose a vital role of CBC in connecting pre-mRNA capping to transcription elongation and alternative splicing via P-TEFb.
The human 7SK small nuclear RNA (snRNA) is an abundant noncoding RNA whose function has been conserved in evolution from invertebrates to humans. It is transcribed by RNA polymerase III (RNAPIII) and ...is located in the nucleus. Together with associated cellular proteins, 7SK snRNA regulates the activity of the positive transcription elongation factor b (P‐TEFb). In humans, this regulation is accomplished by the recruitment of P‐TEFb by the 7SK snRNA‐binding proteins, hexamethylene bisacetamide (HMBA)‐induced mRNA 1/2 (HEXIM1 or HEXIM2), which inhibit the kinase activity of P‐TEFb. P‐TEFb regulates the transition of promoter proximally paused RNA polymerase II (RNAPII) into productive elongation, thereby, allowing efficient mRNA production. The protein composition of the 7SK small nuclear ribonucleoprotein (snRNP) is regulated dynamically. While the Lupus antigen (La)‐related protein 7 (LARP7) is a constitutive component, the methylphosphate capping enzyme (MePCE) associates secondarily to phosphorylate the 5′ end of 7SK snRNA. The release of active P‐TEFb is closely followed by release of HEXIM proteins and both are replaced by heterogeneous nuclear ribonucleoproteins (hnRNPs). The released P‐TEFb activates the expression of most cellular and viral genes. Regulated release of P‐TEFb determines the expression pattern of many of the genes that respond to environmental stimuli and regulate growth, proliferation, and differentiation of cells. WIREs RNA 2012, 3:92–103. doi: 10.1002/wrna.106
This article is categorized under:
RNA Structure and Dynamics > Influence of RNA Structure in Biological Systems
RNA Interactions with Proteins and Other Molecules > Protein–RNA Recognition
RNA Processing > Processing of Small RNAs
Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs
The HIV accessory protein negative factor (Nef) is one of the earliest and most abundantly expressed viral proteins. It is also found in the serum of infected individuals (Caby MP, Lankar D, ...Vincendeau‐Scherrer C, Raposo G, Bonnerot C. Exosomal‐like vesicles are present in human blood plasma. Int Immunol 2005;17:879–887). Extracellular Nef protein has deleterious effects on CD4+ T cells (James CO, Huang MB, Khan M, Garcia‐Barrio M, Powell MD, Bond VC. Extracellular Nef protein targets CD4+ T cells for apoptosis by interacting with CXCR4 surface receptors. J Virol 2004;78:3099–3109), the primary targets of HIV, and can suppress immunoglobulin class switching in bystander B cells (Qiao X, He B, Chiu A, Knowles DM, Chadburn A, Cerutti A. Human immunodeficiency virus 1 Nef suppresses CD40‐dependent immunoglobulin class switching in bystander B cells. Nat Immunol 2006;7:302–310). Nevertheless, the mode of exit of Nef from infected cells remains a conundrum. We found that Nef stimulates its own export via the release of exosomes from all cells examined. Depending on its intracellular location, these Nef exosomes form at the plasma membrane, late endosomes or both compartments in Jurkat, SupT1 and primary T cells, respectively. Nef release through exosomes is conserved also during HIV‐1 infection of peripheral blood lymphocytes (PBLs). Released Nef exosomes cause activation‐induced cell death of resting PBLs in vitro. Thus, HIV‐infected cells export Nef in bioactive vesicles, which facilitate the depletion of CD4+ T cells that is a hallmark of acquired immunodeficiency syndrome (AIDS).
Background and Purpose
To evaluate the association between cumulative exposure to migraine and incidence of ischemic stroke in the Atherosclerosis Risk in Communities (ARIC) study.
Methods
In this ...ongoing, prospective longitudinal community‐based cohort, participants were interviewed to ascertain migraine history at the third visit (1993–1995), followed for ischemic stroke incidence over 20 years. We performed a post hoc analysis to evaluate the association between the age of migraine onset and ischemic stroke.
Results
We identified 447 migraineurs with aura (MA) and 1128 migraineurs without aura (MO) among 11,592 black and white participants. There was an association between the age of MA onset ≥50 years old (average duration = 4.75 years) and ischemic stroke when compared to no headache group (multivariable adjusted HR = 2.17, 95% CI 1.39–3.39, P < .001). MA onset <50 years old (average duration = 28.17 years) was not associated with stroke (multivariable adjusted HR = 1.31, 95% CI 0.86–2.02, P = .212). These results were consistent with our logistic regression model. MO was not associated with increased stroke regardless of the age of onset. The absolute risk for stroke in migraine with aura is 37/447 (8.27%) and migraine without aura is 48/1128 (4.25%).
Conclusion
As compared to the no headache participants, increased stroke risk in late life was observed in participants with late onset of MA. In this cohort, longer cumulative exposure to migraine with visual aura, as would be expected with early onset of migraine, was not associated with increased risk of ischemic stroke in late life. This study underscores the importance of the age of onset of MA in assessing stroke risk in older migraineurs.
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