Mlck1a is expressed in zebrafish thrombocytes and is an essential component of thrombus formation.
BACKGROUND
We have used the advantages of the zebrafish model system to demonstrate which of the vertebrate myosin light chain kinase (MLCK) genes is expressed in thrombocytes and important for thrombus formation.


RESULTS
Here we report that Mlck1a is an essential component of thrombus formation. Phylogenetic data revealed four zebrafish orthologous for three human MLCK genes. To investigate expression of the zebrafish mlck genes in thrombocytes we compared GFP-tagged platelets with other cells by microarray analysis, and showed that mlck1a expression was 4.5-fold enriched in platelets. Furthermore, mlck1a mRNA and mRNA for the platelet-specific cd41 co-localized in thrombi. Expression of other mlck subtypes was lower in GFP-tagged platelets (mlck1b; 0.77-fold enriched) and absent in thrombi (mlck1b, -2, -3). To investigate the role of Mlck1a in thrombus formation, we knocked down mlck1a using two morpholinos. This resulted in impaired morphology changes of platelets adhering on fibrinogen. In a thrombosis model, in which thrombocytes adhere to the vessel wall damaged by laser irradiation, thrombus formation was slowed down in mlck1a-deficient embryos.


CONCLUSIONS
We conclude that Mlck1a is the subtype of MLCK that contributes to platelet shape change and thrombus formation.
Tournoij
E
E
Hubrecht Institute-KNAW and UMC, Utrecht, the Netherlands.
Weber
G J
GJ
Akkerman
J W N
JW
de Groot
P G
PG
Zon
L I
LI
Moll
F L
FL
Schulte-Merker
S
S
D000818:Animals; D030801:Animals, Genetically Modified; D001792:Blood Platelets / Q000201:enzymology*; D048430:Cell Shape; D004195:Disease Models, Animal; D005340:Fibrinogen / Q000378:metabolism; D020869:Gene Expression Profiling / Q000379:methods; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D055785:Gene Knockdown Techniques; D009219:Myosin-Light-Chain Kinase / Q000097:blood* / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D010973:Platelet Adhesiveness; D040201:Platelet Membrane Glycoprotein IIb / Q000097:blood; D012333:RNA, Messenger / Q000097:blood; D011993:Recombinant Fusion Proteins / Q000097:blood; D013927:Thrombosis / Q000097:blood / Q000201:enzymology* / Q000235:genetics; D015027:Zebrafish / Q000097:blood* / Q000196:embryology / Q000235:genetics; D029961:Zebrafish Proteins / Q000097:blood* / Q000235:genetics
D040201:Platelet Membrane Glycoprotein IIb; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D029961:Zebrafish Proteins; D005340:Fibrinogen; D009219:Myosin-Light-Chain Kinase