L-selectin shedding is activated specifically within transmigrating pseudopods of monocytes to regulate cell polarity in vitro.
Journal Article (Journal Article)
L-selectin is a cell adhesion molecule that tethers free-flowing leukocytes from the blood to luminal vessel walls, facilitating the initial stages of their emigration from the circulation toward an extravascular inflammatory insult. Following shear-resistant adhesion to the vessel wall, L-selectin has frequently been reported to be rapidly cleaved from the plasma membrane (known as ectodomain shedding), with little knowledge of the timing or functional consequence of this event. Using advanced imaging techniques, we observe L-selectin shedding occurring exclusively as primary human monocytes actively engage in transendothelial migration (TEM). Moreover, the shedding was localized to transmigrating pseudopods within the subendothelial space. By capturing monocytes in midtransmigration, we could monitor the subcellular distribution of L-selectin and better understand how ectodomain shedding might contribute to TEM. Mechanistically, L-selectin loses association with calmodulin (CaM; a negative regulator of shedding) specifically within transmigrating pseudopods. In contrast, L-selectin/CaM interaction remained intact in nontransmigrated regions of monocytes. We show phosphorylation of L-selectin at Ser 364 is critical for CaM dissociation, which is also restricted to the transmigrating pseudopod. Pharmacological or genetic inhibition of L-selectin shedding significantly increased pseudopodial extensions in transmigrating monocytes, which potentiated invasive behavior during TEM and prevented the establishment of front/back polarity for directional migration persistence once TEM was complete. We conclude that L-selectin shedding directly regulates polarity in transmigrated monocytes, which affirms an active role for this molecule in driving later stages of the multistep adhesion cascade.
Full Text
Duke Authors
Cited Authors
- Rzeniewicz, K; Newe, A; Rey Gallardo, A; Davies, J; Holt, MR; Patel, A; Charras, GT; Stramer, B; Molenaar, C; Tedder, TF; Parsons, M; Ivetic, A
Published Date
- March 24, 2015
Published In
Volume / Issue
- 112 / 12
Start / End Page
- E1461 - E1470
PubMed ID
- 25775539
Pubmed Central ID
- PMC4378423
Electronic International Standard Serial Number (EISSN)
- 1091-6490
Digital Object Identifier (DOI)
- 10.1073/pnas.1417100112
Language
- eng
Conference Location
- United States