Integrator subunit 4 is a 'Symplekin-like' scaffold that associates with INTS9/11 to form the Integrator cleavage module.

Integrator (INT) is a transcriptional regulatory complex associated with RNA polymerase II that is required for the 3'-end processing of both UsnRNAs and enhancer RNAs. Integrator subunits 9 (INTS9) and INTS11 constitute the catalytic core of INT and are paralogues of the cleavage and polyadenylation specificity factors CPSF100 and CPSF73. While CPSF73/100 are known to associate with a third protein called Symplekin, there is no paralog of Symplekin within INT raising the question of how INTS9/11 associate with the other INT subunits.

Cajal bodies are linked to genome conformation.

The mechanisms underlying nuclear body (NB) formation and their contribution to genome function are unknown. Here we examined the non-random positioning of Cajal bodies (CBs), major NBs involved in spliceosomal snRNP assembly and their role in genome organization. CBs are predominantly located at the periphery of chromosome territories at a multi-chromosome interface.

PA28γ is a novel corepressor of HTLV-1 replication and controls viral latency.

Unlabelled: The establishment of a latent reservoir by human tumor viruses is a vital step in initiating cellular transformation and represents a major shortcoming to current therapeutic strategies and the ability to eradicate virus-infected cells. Human T-cell leukemia virus type 1 (HTLV-1) establishes a lifelong infection and is linked to adult T-cell leukemia lymphoma (ATLL). Here, we demonstrate that HTLV-1 p30 recruits the cellular proteasome activator PA28γ onto the viral tax/rex mRNA to prevent its nuclear export and suppress virus replication.

SRSF1 regulates the assembly of pre-mRNA processing factors in nuclear speckles.

The mammalian cell nucleus is compartmentalized into nonmembranous subnuclear domains that regulate key nuclear functions. Nuclear speckles are subnuclear domains that contain pre-mRNA processing factors and noncoding RNAs. Many of the nuclear speckle constituents work in concert to coordinate multiple steps of gene expression, including transcription, pre-mRNA processing and mRNA transport.

Dynamic force-induced direct dissociation of protein complexes in a nuclear body in living cells.

Despite past progress in understanding mechanisms of cellular mechanotransduction, it is unclear whether a local surface force can directly alter nuclear functions without intermediate biochemical cascades. Here we show that a local dynamic force via integrins results in direct displacements of coilin and SMN proteins in Cajal bodies and direct dissociation of coilin-SMN associated complexes. Spontaneous movements of coilin increase more than those of SMN in the same Cajal body after dynamic force application.

Nucleation of nuclear bodies by RNA.

The biogenesis of the many functional compartments contained in the mammalian cell nucleus is poorly understood. More specifically, little is known regarding the initial nucleation step required for nuclear body formation. Here we show that RNA can function as a structural element and a nucleator of nuclear bodies.

Activation of beta-catenin signaling pathways by classical G-protein-coupled receptors: mechanisms and consequences in cycling and non-cycling cells.

Wnt signaling pathways are some of the most intensely studies in all of biology. Recently, a number of classical heterotrimeric G protein coupled receptors (GPCRs) have been shown to activate the canonical Wnt pathway, culminating in the stabilization of beta-catenin and induction of transcription of genes regulated by the Tcf/Lef family of transactivators. However, mechanisms by which these GPCRs accomplish this differ in key ways, and in some circumstances, the phenotypes produced are novel.