Hippo signaling plays a crucial role in growth control and tumor suppression by regulating cell proliferation, apoptosis, and differentiation. How Hippo signaling is regulated has been under extensive investigation. Over the past three years, an increasing amount of data have supported a model of actin cytoskeleton blocking Hippo signaling activity to allow nuclear accumulation of a downstream effector, Yki/Yap/Taz. On the other hand, Hippo signaling negatively regulates actin cytoskeleton organization. This review provides insight on the mutual regulatory mechanisms between Hippo signaling and actin cytoskeleton for a tight control of cell behaviors during animal development, and points out outstanding questions for further investigations.

Mediator is a highly conserved large protein complex (25 proteins,>1000 kD a) and preeminently responsible for eukaryotic transcription, which contains a dissociable ‘Cdk8 module’. Although increasing evidence demonstrates that Cdk8 module plays both positive and negative roles in transcription regulation, the detailed structure, and subunit organization, molecular mechanism how it regulates transcription remain elusive. Here we used single-particle electron microscopy to characterize the structure and subunit organization of the Cdk8 module and illuminated the substantial mobility of the Med13 subunit results in the structural flexibility. The Cdk8 module interaction with core Mediator is concurrent with active transcription in vivo. An interaction with the Cdk8 module induces core Mediator into very extended conformation in vitro, which is presumed to be an active functional state of Mediator. Taken together, our results illuminated the detailed architecture of Cdk8 module, and suggested the Cdk8 module could positively regulate transcription by modulating Mediator conformation.

Mycosin-1 protease (MycP1) is a serine protease anchored to the inner membrane of Mycobacterium tuberculosis, and is essential in virulence factor secretion through the ESX-1 type VII secretion system (T7SS). Bacterial physiology studies demonstrated that MycP1 plays a dual role in the regulation of ESX-1 secretion and virulence, primarily through cleavage of its secretion substrate EspB. MycP1 contains a putative N-terminal inhibitory propeptide and a catalytic triad of Asp-His-Ser, classic hallmarks of a subtilase family serine protease. The MycP1 propeptide was previously reported to be initially inactive and activated after prolonged incubation. In this study, we have determined crystal structures of MycP1 with (MycP1^24-422) and without (MycP1^63-422) the propeptide, and conducted EspB cleavage assays using the two proteins. Very high structural similarity was observed in the two crystal structures. Interestingly, protease assays demonstrated positive EspB cleavage for both proteins, indicating that the putative propeptide does not inhibit protease activity. Molecular dynamic simulations showed higher rigidity in regions guarding the entrance to the catalytic site in MycP1^24-422 than in MycP1^63-422, suggesting that the putative propeptide might contribute to the conformational stability of the active site cleft and surrounding regions.

Tumor-associated macrophages (TAMs) mostly exhibit M2-like (alternatively activated) properties and play positive roles in angiogenesis and tumorigenesis. Vascular endothelial growth factor (VEGF) is a key angiogenic factor. During tumor development, TAMs secrete VEGF and other factors to promote angiogenesis; thus, anti-treatment against TAMs and VEGF can repress cancer development, which has been demonstrated in clinical trials and on an experimental level. In the present work, we show that miR-150 is an oncomir because of its promotional effect on VEGF. MiR-150 targets TAMs to up-regulate their secretion of VEGF in vitro. With the utilization of cell-derived vesicles, named microvesicles (MVs), we transferred antisense RNA targeted to miR-150 into mice and found that the neutralization of miR-150 down-regulates miR-150 and VEGF levels in vivo and attenuates angiogenesis. Therefore, we proposed the therapeutic potential of neutralizing miR-150 to treat cancer and demonstrated a novel, natural, microvesicle-based method for the transfer of nucleic acids.

In all six members of TRPV channel subfamily, there is an ankyrin repeat domain (ARD) in their intracellular Ntermini. Ankyrin (ANK) repeat, a common motif with typically 33 residues in each repeat, is primarily involved in protein-protein interactions. Despite the sequence similarity among the ARDs of TRPV channels, the structure of TRPV3-ARD, however, remains unknown. Here, we report the crystal structure of TRPV3-ARD solved at 1.95 ? resolution, which reveals six-ankyrin repeats. While overall structure of TRPV3-ARD is similar to ARDs from other members of TRPV subfamily; it, however, features a noticeable finger 3 loop that bends over and is stabilized by a network of hydrogen bonds and hydrophobic packing, instead of being flexible as seen in known TRPV-ARD structures. Electrophysiological recordings demonstrated that mutating key residues R225, R226, Q255, and F249 of finger 3 loop altered the channel activities and pharmacology. Taken all together, our findings show that TRPV3-ARD with characteristic finger 3 loop likely plays an important role in channel function and pharmacology.