Simultaneous tracking of 3D actin and microtubule strains in individual MLO-Y4 osteocytes under oscillatory flow.
Osteocytes in vivo experience complex fluid shear flow patterns to activate mechanotransduction pathways. The actin and microtubule (MT) cytoskeletons have been shown to play an important role in the osteocyte's biochemical response to fluid shear loading. The dynamic nature of physiologically relevant fluid flow profiles (i.e., 1Hz oscillatory flow) impedes the ability to image and study both actin and MT cytoskeletons simultaneously in the same cell with high spatiotemporal resolution. To overcome these limitations, a multi-channel quasi-3D microscopy technique was developed to track the actin and MT networks simultaneously under steady and oscillatory flow. Cells displayed high intercellular variability and intracellular cytoskeletal variability in strain profiles. Shear Exz was the predominant strain in both steady and oscillatory flows in the form of viscoelastic creep and elastic oscillations, respectively. Dramatic differences were seen in oscillatory flow, however. The actin strains displayed an oscillatory strain profile more often than the MT networks in all the strains tested and had a higher peak-to-trough strain magnitude. Taken together, the actin networks are the more responsive cytoskeletal networks in osteocytes under oscillatory flow and may play a bigger role in mechanotransduction pathway activation and regulation.
Bone Bioengineering Laboratory, Department of Biomedical Engineering, Columbia University, NY 10027, USA.
Andrew D
AD
Baik
Jun
J
Qiu
Elizabeth M C
EM
Hillman
Cheng
C
Dong
X Edward
XE
Guo
D000199:Actins / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D040542:Mechanotransduction, Cellular; D051379:Mice; D008853:Microscopy / Q000379:methods; D008870:Microtubules / Q000502:physiology*; D010011:Osteocytes / Q000378:metabolism / Q000502:physiology*; D013314:Stress, Mechanical
D000199:Actins