Increased smooth muscle contractility in mice deficient for neuropilin 2.
Neuropilins (NRPs) are transmembrane receptors that bind class 3 semaphorins and VEGF family members to regulate axon guidance and angiogenesis. Although expression of NRP1 by vascular smooth muscle cells (SMCs) has been reported, NRP function in smooth muscle (SM) in vivo is unexplored. Using Nrp2(+/LacZ) and Nrp2(+/gfp) transgenic mice, we observed robust and sustained expression of Nrp2 in the SM compartments of the bladder and gut, but no expression in vascular SM, skeletal muscle, or cardiac muscle. This expression pattern was recapitulated in vitro using primary human SM cell lines. Alterations in cell morphology after treatment of primary visceral SMCs with the NRP2 ligand semaphorin-3F (SEMA3F) were accompanied by inhibition of RhoA activity and myosin light chain phosphorylation, as well as decreased cytoskeletal stiffness. Ex vivo contractility testing of bladder muscle strips exposed to electrical stimulation or soluble agonists revealed enhanced tension generation of tissues from mice with constitutive or SM-specific knockout of Nrp2, compared with controls. Mice lacking Nrp2 also displayed increased bladder filling pressures, as assessed by cystometry in conscious mice. Together, these findings identify Nrp2 as a mediator of prorelaxant stimuli in SMCs and suggest a novel function for Nrp2 as a regulator of visceral SM contractility.
Vascular Biology Program, Children's Hospital Boston, Boston, Massachusetts 02115, USA. diane.bielenberg@childrens.harvard.edu
Diane R
DR
Bielenberg
Abhishek
A
Seth
Akio
A
Shimizu
Kristine
K
Pelton
Vivian
V
Cristofaro
Aruna
A
Ramachandran
Bernadette M M
BM
Zwaans
Cheng
C
Chen
Ramaswamy
R
Krishnan
Meetu
M
Seth
Lin
L
Huang
Seiji
S
Takashima
Michael
M
Klagsbrun
Maryrose P
MP
Sullivan
Rosalyn M
RM
Adam
D000818:Animals; D048430:Cell Shape / Q000187:drug effects; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D005260:Female; D017353:Gene Deletion; D066257:Heparin-binding EGF-like Growth Factor; D006801:Humans; D066298:In Vitro Techniques; D036341:Intercellular Signaling Peptides and Proteins / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000166:cytology; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D039943:Neuropilin-2 / Q000172:deficiency* / Q000378:metabolism*; D009928:Organ Specificity / Q000187:drug effects; D034421:Sus scrofa; D001743:Urinary Bladder / Q000166:cytology / Q000378:metabolism; D054460:rho-Associated Kinases / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
C587883:HBEGF protein, human; C587884:Hbegf protein, mouse; D066257:Heparin-binding EGF-like Growth Factor; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D039943:Neuropilin-2; C491230:SEMA3F protein, human; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein