Development of a Cell Culture System to Examine the Acclimation, Contraction, and Cytoskeletal Remodeling of A7r5 Smooth Muscle Cells to Microgravity

Abstract

Few studies have examined the acclimation and contraction of smooth muscle cells in microgravity. In addition, the cytoskeleton in smooth muscle has not been thoroughly examined habituated to microgravity. Although previous studies have noted that the phenotype of smooth muscle may be gravity dependent, those that have been performed have utilized simulated microgravity. The cytoskeleton has been implicated by several investigators as allowing single cells in vitro to respond to changes in gravity and may serve as a gravity sensor (reviewed in Vorselen et al., 2016) at the individual cell level. This investigation will focus on the effect of microgravity on the alpha‐actin, beta‐actin, and myosin components of the cytoskeleton in resting and contracting A7r5 smooth muscle cells. We have provided evidence of differential remodeling of the alpha‐actin, beta‐actin, and myosin cytoskeletal domains in smooth muscle (Brown et al., 2006, Li et al., 2001, Fultz et al., 2000, Fultz and Wright, 2003, and Thatcher et al., 2011). At rest these are organized into filamentous stress cables that run the length of the cell. Upon stimulation, α‐actin and myosin interact to produce force that results in shorting of the cell. This shortening applies stress on the beta‐actin filaments which then undergo subsequent remodeling into configuration that holds the cell in the shortened state. Alpha‐actin and myosin then undergo disassembly/reassembly into a configuration that is optimized for further contraction and aggregate into podosomes that appear as column‐like structures in the contracted cell. While we have proposed that this remodeling is essential mechanism in the development and maintenance of force in smooth muscle (Li et al., 2001). Others have proposed that pododome formation may be relevant in the invasiveness of smooth muscle that is observed in cardiovascular disease as podosomes formation correlates with cell motility and localized degradation of the extracellular matrix (Burgstaller and Gimona, 2005; Lener et al., 2006; Murphy and Courtneidge, 2011). In collaboration with SpaceTango (Lexington, KY) and the Craft Academy for Excellence in Science and Mathematics at Morehead State University, a cell culture system has been developed that will allow for the culture, visualization, stimulation, and subsequent fixation of A7r5 cells aboard the International Space Station. Upon return to Earth, components of the cytoskeleton will be examined by fluorescent microscopy to investigate if microgravity alters the characteristic remodeling observed on Earth.Support or Funding InformationThis material is based upon work supported by NASA Kentucky under NASA award No: NNX15AR69H.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.