Cellular nonmuscle myosins NMHC-IIA and NMHC-IIB and vertebrate heart looping.
Flectin, a protein previously described to be expressed in a left-dominant manner in the embryonic chick heart during looping, is a member of the nonmuscle myosin II (NMHC-II) protein class. During looping, both NMHC-IIA and NMHC-IIB are expressed in the mouse heart on embryonic day 9.5. The patterns of localization of NMHC-IIB, rather than NMHC-IIA in the mouse looping heart and in neural crest cells, are equivalent to what we reported previously for flectin. Expression of full-length human NMHC-IIA and -IIB in 10 T1/2 cells demonstrated that flectin antibody recognizes both isoforms. Electron microscopy revealed that flectin antibody localizes in short cardiomyocyte cell processes extending from the basal layer of the cardiomyocytes into the cardiac jelly. Flectin antibody also recognizes stress fibrils in the cardiac jelly in the mouse and chick heart; while NMHC-IIB antibody does not. Abnormally looping hearts of the Nodal(Delta 600) homozygous mouse embryos show decreased NMHC-IIB expression on both the mRNA and protein levels. These results document the characterization of flectin and extend the importance of NMHC-II and the cytoskeletal actomyosin complex to the mammalian heart and cardiac looping.
Lu
Wenge
W
Department of Pediatrics, USF/ACH-Children's Research Institute, St. Petersburg, Florida 33701, USA.
Seeholzer
Steven H
SH
Han
Mingda
M
Arnold
Anne-Sophie
AS
Serrano
Maria
M
Garita
Barbara
B
Philp
Nancy J
NJ
Farthing
Cassandra
C
Steele
Peter
P
Chen
Jizhen
J
Linask
Kersti K
KK
D000818:Animals; D002460:Cell Line; D002642:Chick Embryo; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter / Q000235:genetics; D006321:Heart / Q000196:embryology*; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D009206:Myocardium / Q000378:metabolism*; D055457:Nodal Protein / Q000235:genetics / Q000378:metabolism; D024507:Nonmuscle Myosin Type IIA / Q000235:genetics / Q000378:metabolism*; D024501:Nonmuscle Myosin Type IIB / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D040901:Proteomics; D012333:RNA, Messenger / Q000235:genetics; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D016326:Extracellular Matrix Proteins; D055457:Nodal Protein; D012333:RNA, Messenger; D024507:Nonmuscle Myosin Type IIA; D024501:Nonmuscle Myosin Type IIB