Septin Phosphorylation and Coiled-Coil Domains Function in Cell and Septin Ring Morphology in the Filamentous Fungus Ashbya Gossypii

Septins are a class of GTP-binding proteins conserved throughout many eukaryotes. Individual septin subunits associate with one another and assemble into heteromeric complexes that form filaments and higher-order structures in vivo. The mechanisms underlying the assembly and maintenance of higher-order structures in cells remain poorly understood. Septins in several organisms have been shown to be phosphorylated, although precisely how septin phosphorylation may be contributing to the formation of high-order septin structures is unknown. Four of the five septins expressed in the filamentous fungus, Ashbya gossypii, are phosphorylated, and we demonstrate here the diverse roles of these phosphorylation sites in septin ring formation and septin dynamics, as well as cell morphology and viability. Intriguingly, the alteration of specific sites in Cdc3p and Cdc11p leads to a complete loss of higher-order septin structures, implicating septin phosphorylation as a regulator of septin structure formation. Introducing phosphomimetic point mutations to specific sites in Cdc12p and Shs1p causes cell lethality, highlighting the importance of normal septin modification in overall cell function and health. In addition to discovering roles for phosphorylation, we also present diverse functions for conserved septin domains in the formation of septin higher-order structure. We previously showed the requirement for the Shs1p coiled-coil domain in limiting septin ring size and reveal here that, in contrast to Shs1p, the coiled-coil domains of Cdc11p and Cdc12p are required for septin ring formation. Our results as a whole reveal novel roles for septin phosphorylation and coiled-coil domains in regulating septin structure and function

Micron-Scale Plasma Membrane Curvature is Recognized by the Septin Cytoskeleton

Cells change shape in response to diverse environmental and developmental conditions, creating topologies with micron-scale features. Although individual proteins can sense nanometer-scale membrane curvature, it is unclear if a cell could also use nanometer-scale components to sense micron-scale contours, such as the cytokinetic furrow and base of neuronal branches. Septins are filament-forming proteins that serve as signaling platforms and are frequently associated with areas of the plasma membrane where there is micron-scale curvature, including the cytokinetic furrow and the base of cell protrusions. We report here that fungal and human septins are able to distinguish between different degrees of micron-scale curvature in cells. By preparing supported lipid bilayers on beads of different curvature, we reconstitute and measure the intrinsic septin curvature preference. We conclude that micron-scale curvature recognition is a fundamental property of the septin cytoskeleton that provides the cell with a mechanism to know its local shape

Septin assemblies form by diffusion-driven annealing on membranes

Author Posting. © The Author(s), 2013. This is the author's version of the work. It is posted here by permission of National Academy of Sciences for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences of the United States of America 111 (2014): 2146-2151, doi:10.1073/pnas.1314138111.Septins assemble into filaments and higher-order structures that act as scaffolds for diverse cell functions including cytokinesis, cell polarity, and membrane remodeling. Despite their conserved role in cell organization, little is known about how septin filaments elongate and are knit together into higher-order assemblies. Using fluorescence correlation spectroscopy (FCS), we determined that cytosolic septins are in small complexes suggesting that septin filaments are not formed in the cytosol. When the plasma membrane of live cells is monitored by total internal reflection fluorescence (TIRF) microscopy, we see that septin complexes of variable size diffuse in two dimensions. Diffusing septin complexes collide and make end-on associations to form elongated filaments and higher-order structures, an assembly process we call annealing. Septin assembly by annealing can be reconstituted in vitro on supported lipid bilayers with purified septin complexes. Using the reconstitution assay, we show that septin filaments are highly flexible, grow only from free filament ends and do not exchange subunits in the middle of filaments. This work shows for the first time that annealing is an intrinsic property of septins in the presence of membranes and demonstrates that cells exploit this mechanism to build large septin assemblies.This project was supported with funding from by NSF (MCB-507511, ASG) and NIH (GM100160, TT and ASG), and Colwin, Lemann and Spiegel summer fellowships and The Nikon Award for summer investigation at MBL in Woods Hole, MA (ASG) and instrument support from Micro Video Instruments (MVI).2014-07-2

Flexible and conformable strain gauges for smart pressure sensors systems: Static and dynamic characterization

An innovative segment of the semiconductor and electronics industry in the last years is driven by new sensors embedded in smart devices and systems with thin form factor, connected to existing infrastructures via standard communication interfaces. The increased maturity of industrial sensor technologies and associated readout electronics enabled new products penetrating multiple market sectors. Among the different classes of smart sensing systems that can be realized with thin and truly flexible form factor, thin film strain gauges are ideally suited for the implementation of pressure sensing membranes. In this work we will focus on the development of static and dynamic testing methods of a strain gauge module whose applications are intended as a flexible and conformable strain/pressure sensor, adaptable for wireless communications

Crizotinib plus radiotherapy in brain oligoprogressive NSCLC ROS1 rearranged and PD-L1 strong

ROS1+ patients represent a unique molecular subset of non-small cell lung cancer (NSCLC). Early phase clinical trials have shown a high response rate to crizotinib in these patients. We describe a case of an 18 years old woman, never smoker, with NSCLC ROS1+ and miliary brain metastases treated with crizotinib and radiotherapy. From October 2014 to June 2015 the Patient was treated with crizotinib. The first intracranial time to progression (IT-TTP) occurred after 7 months; the patient underwent stereotactic radiosurgery (SRS) and continued TKI treatment. The second IT-TTP appeared after 16 months. A continued response in the chest was observed for all the 23 months of crizotinib treatment. At the progression, we assessed programmed death ligand 1 (PD-L1) expression by immunohistochemistry, that resulted highly expressed. Our report indicates that the integration of crizotinib with local treatments should be considered in ROS1 NSCLC patients experiencing oligometastatic progression. Moreover, this case is an example of PD-L1 strong in oncogene addicted patients

Men's help-seeking in the first year after diagnosis of localised prostate cancer.

This study describes sources of support utilised by men with localised prostate cancer in the first year after diagnosis and examines characteristics associated with help-seeking for men with unmet needs. A cross-sectional survey of 331 patients from a population-based sample who were in the first year after diagnosis (M = 9.6, SD = 1.9) was conducted to assess sources of support, unmet supportive care needs, domain-specific quality of life and psychological distress. Overall, 82% of men reported unmet supportive care needs. The top five needs were sexuality (58%); prostate cancer-specific (57%); psychological (47%); physical and daily living (41%); and health system and information (31%). Professional support was most often sought from doctors (51%). Across most domains, men who were older (Ps ≤ 0.03), less well educated (Ps ≤ 0.04) and more depressed (Ps ≤ 0.05) were less likely to seek help for unmet needs. Greater sexual help-seeking was related to better sexual function (P = 0.03), higher education (P ≤ 0.03) and less depression (P = 0.05). Unmet supportive care needs are highly prevalent after localised prostate cancer diagnosis with older age, lower education and higher depression apparent barriers to help-seeking. Interventions that link across medicine, nursing and community based peer support may be an accessible approach to meeting these needs. Clinical Trial Registry: Trial Registration: ACTRN12611000392965