Programming of synthetic regulatory DNA for cell-type targeting in humans.

In a recent study in Nature, Gosai et al. introduce a framework to engineer and validate synthetic DNA regulatory elements showing cell-type-specific activity in human cell lines, closing the distance to the machine-driven design of functional regulatory sequences with therapeutic applications in humans.

UMAD1 contributes to ESCRT-III dynamic subunit turnover during cytokinetic abscission.

Abscission is the final stage of cytokinesis whereby the midbody, a thin intercellular bridge, is resolved to separate the daughter cells. Cytokinetic abscission is mediated by the endosomal sorting complex required for transport (ESCRT), a conserved membrane remodelling machinery. The midbody organiser CEP55 recruits early acting ESCRT factors such as ESCRT-I and ALIX (also known as PDCD6IP), which subsequently initiate the formation of ESCRT-III polymers that sever the midbody.

The ESCRT machinery counteracts Nesprin-2G-mediated mechanical forces during nuclear envelope repair.

Transient nuclear envelope ruptures during interphase (NERDI) occur due to cytoskeletal compressive forces at sites of weakened lamina, and delayed NERDI repair results in genomic instability. Nuclear envelope (NE) sealing is completed by endosomal sorting complex required for transport (ESCRT) machinery. A key unanswered question is how local compressive forces are counteracted to allow efficient membrane resealing.

Midbody Remnant Inheritance Is Regulated by the ESCRT Subunit CHMP4C.

The inheritance of the midbody remnant (MBR) breaks the symmetry of the two daughter cells, with functional consequences for lumen and primary cilium formation by polarized epithelial cells, and also for development and differentiation. However, despite its importance, neither the relationship between the plasma membrane and the inherited MBR nor the mechanism of MBR inheritance is well known. Here, the analysis by correlative light and ultra-high-resolution scanning electron microscopy reveals a membranous stalk that physically connects the MBR to the apical membrane of epithelial cells.

CC2D1B Coordinates ESCRT-III Activity during the Mitotic Reformation of the Nuclear Envelope.

The coordinated reformation of the nuclear envelope (NE) after mitosis re-establishes the structural integrity and the functionality of the nuclear compartment. The endosomal sorting complex required for transport (ESCRT) machinery, a membrane remodeling pathway that is highly conserved in eukaryotes, has been recently involved in NE resealing by mediating the annular fusion of the nuclear membrane (NM). We show here that CC2D1B, a regulator of ESCRT polymerization, is required to re-establish the nuclear compartmentalization by coordinating endoplasmic reticulum (ER) membrane deposition around chromatin disks with ESCRT-III recruitment to the reforming NE.

Biogenesis and Function of T Cell-Derived Exosomes.

Exosomes are a particular type of extracellular vesicle, characterized by their endosomal origin as intraluminal vesicles present in large endosomes with a multivesicular structure. After these endosomes fuse with the plasma membrane, exosomes are secreted into the extracellular space. The ability of exosomes to carry and selectively deliver bioactive molecules (e.

ESCRT machinery: Damage control at the nuclear membrane.

Rupture of the nuclear envelope (NE) during interphase is thought to be an infrequent event in healthy cells. Two papers recently published in Science describe the transient disruption of the NE continuity in cells migrating through confined spaces, and uncover an essential role for the Endosomal Sorting Complex Required for Transport (ESCRT) machinery in the resealing of these nuclear discontinuities.

Cutting Edge: Regulation of Exosome Secretion by the Integral MAL Protein in T Cells.

Exosomes secreted by T cells play an important role in coordinating the immune response. HIV-1 Nef hijacks the route of exosome secretion of T cells to modulate the functioning of uninfected cells. Despite the importance of the process, the protein machinery involved in exosome biogenesis is yet to be identified.

Regulated vesicle fusion generates signaling nanoterritories that control T cell activation at the immunological synapse.

How the vesicular traffic of signaling molecules contributes to T cell receptor (TCR) signal transduction at the immunological synapse remains poorly understood. In this study, we show that the protein tyrosine kinase Lck, the TCRζ subunit, and the adapter LAT traffic through distinct exocytic compartments, which are released at the immunological synapse in a differentially regulated manner. Lck vesicular release depends on MAL protein.

The role of membrane rafts in Lck transport, regulation and signalling in T-cells.

Tyrosine phosphorylation is one of the key covalent modifications that occur in multicellular organisms. Since its discovery more than 30 years ago, tyrosine phosphorylation has come to be understood as a fundamentally important mechanism of signal transduction and regulation in all eukaryotic cells. The tyrosine kinase Lck (lymphocyte-specific protein tyrosine kinase) plays a crucial role in the T-cell response by transducing early activation signals triggered by TCR (T-cell receptor) engagement.

The formin INF2 regulates basolateral-to-apical transcytosis and lumen formation in association with Cdc42 and MAL2.

Transcytosis is a widespread pathway for apical targeting in epithelial cells. MAL2, an essential protein of the machinery for apical transcytosis, functions by shuttling in vesicular carriers between the apical zone and the cell periphery. We have identified INF2, an atypical formin with actin polymerization and depolymerization activities, which is a binding partner of MAL2.