The new anti-actin agent dihydrohalichondramide reveals fenestrae-forming centers in hepatic endothelial cells
1 Laboratory for Cell Biology and Histology, Free University of Brussels (VUB), Laarbeeklaan 103, 1090 Brussels-Jette, Belgium
2 Department of Physiology and Biophysics, Health Science Center, State University of New York at Stony Brook (SUNY), Stony Brook, NY 11794-8661, New York, USA
3 Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 9506, USA
4 Department of Marine Sciences, University of the Ryukyus, Nishihara, Okinawa 903-01, Japan
5 Department of Hematology and Immunology, Free University of Brussels (VUB), Laarbeeklaan 103, 1090 Brussels-Jette, Belgium
BMC Cell Biology 2002, 3:7 doi:10.1186/1471-2121-3-7Published: 21 March 2002
Liver sinusoidal endothelial cells (LSECs) react to different anti-actin agents by increasing their number of fenestrae. A new structure related to fenestrae formation could be observed when LSECs were treated with misakinolide. In this study, we investigated the effects of two new actin-binding agents on fenestrae dynamics. High-resolution microscopy, including immunocytochemistry and a combination of fluorescence- and scanning electron microscopy was applied.
Halichondramide and dihydrohalichondramide disrupt microfilaments within 10 minutes and double the number of fenestrae in 30 minutes. Dihydrohalichondramide induces fenestrae-forming centers, whereas halichondramide only revealed fenestrae-forming centers without attached rows of fenestrae with increasing diameter. Correlative microscopy showed the absence of actin filaments (F-actin) in sieve plates and fenestrae-forming centers. Comparable experiments on umbilical vein endothelial cells and bone marrow sinusoidal endothelial cells revealed cell contraction without the appearance of fenestrae or fenestrae-forming centers.
(I) A comparison of all anti-actin agents tested so far, revealed that the only activity that misakinolide and dihydrohalichondramide have in common is their barbed end capping activity; (II) this activity seems to slow down the process of fenestrae formation to such extent that it becomes possible to resolve fenestrae-forming centers; (III) fenestrae formation resulting from microfilament disruption is probably unique to LSECs.