Lymphocyte microvilli are dynamic, actin-dependent structures that do not require Wiskott-Aldrich syndrome protein (WASp) for their morphology.

Abstract

Short microvilli cover the surfaces of circulating mammalian lymphocytes. The surfaces of monocytes and neutrophils are very different, containing ruffles as their predominant structure. In this study, we present the first quantitative characterization of lymphocyte microvilli. From analysis of scanning electron micrographs, we find that median microvillar length and surface density range from 0.3 to 0.4 microm and 2 to 4 microvilli/microm(2), respectively, on lymphocytes from a variety of sources. As with similar structures from other cells, lymphocyte microvilli contain parallel bundles of actin filaments. Lymphocyte microvilli rapidly disassemble when exposed to the actin-sequestering molecule, Latrunculin A. This disassembly parallels cellular actin filament depolymerization and is complete within 2 minutes, suggesting that lymphocyte microvilli undergo continuous assembly and disassembly. In contrast to previous reports suggesting lymphocyte microvillar density to be reduced on lymphocytes from Wiskott-Aldrich syndrome (WAS) patient, we find no such deficiency in either mouse or human WAS protein (WASp)-deficient lymphocytes. These results suggest that WASp is either not involved in or is redundant in the rapid dynamics of lymphocyte microvilli.

• Authors: Sonja Majstoravich, Jinyi Zhang, Susan Nicholson-Dykstra, Stefan Linder, Wilhelm Friedrich, Katherine A Siminovitch, Henry N Higgs
• Journal: Blood (Blood) Vol. 104 Issue 5 Pg. 1396-403 (Sep 01 2004) ISSN: 0006-4971 [Print] United States
• PMID: 15130947 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Actins
• Proteins
• WAS protein, human
• Was protein, mouse
• Wiskott-Aldrich Syndrome Protein

Topics

• Actins (metabolism)
• Animals
• Humans
• Lymphocytes (metabolism, ultrastructure)
• Mice
• Mice, Inbred C57BL
• Mice, Knockout
• Microscopy, Electron
• Microscopy, Electron, Scanning
• Microvilli (metabolism, ultrastructure)
• Proteins (genetics, metabolism)
• Wiskott-Aldrich Syndrome (metabolism, pathology)
• Wiskott-Aldrich Syndrome Protein