Modulation of factors affecting optic nerve head astrocyte migration.
OBJECTIVE
The authors investigated the role of myosin light chain kinase (MYLK) and transforming growth factor beta (TGFbeta) receptor pathways in optic nerve head (ONH) astrocyte migration. They further investigated how the expression of these genes is altered by elevated hydrostatic pressure (HP).


METHODS
PCR was used to determine the isoforms of MYLK expressed in ONH astrocytes. siRNAs against MYLK (all isoforms) and TGFbeta receptor 2 (TGFBR2) were prepared and tested for effects on the migration of cultured ONH astrocytes. Finally, the effects of elevated HP (24-96 hours) on the expression of MYLK isoforms and selected TGFbeta pathway components were measured.


RESULTS
Multiple isoforms of MYLK are present in ONH astrocytes from Caucasian (CA) and African American (AA) donors. Both populations express the short form (MYLK-130) and the long form (MYLK-210) of MYLK and a splicing variant within MYLK-210. MYLK-directed siRNA decreased MYLK expression and cell migration compared with control siRNA. siRNA directed against TGFbeta receptor 2 also decreased cell migration compared with control and decreased extracellular matrix genes regulated by TGFbeta signaling. Elevated HP increased the expression of MYLK-130 and MYLK-210 in both populations of astrocytes. However, TGFbeta2 was uniquely upregulated by exposure to elevated HP in CA compared with AA astrocytes.


CONCLUSIONS
Differential expression of TGFbeta pathway genes and MYLK isoforms observed in populations of glaucomatous astrocytes applies to the elevated HP model system. MYLK may be a new target for intervention in glaucoma to alter reactive astrocyte migration in the ONH.
Miao
Haixi
H
Department of Ophthalmology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA.
Crabb
Andrea W
AW
Hernandez
M Rosario
MR
Lukas
Thomas J
TJ
D001741:Black or African American; D001253:Astrocytes / Q000502:physiology*; D001381:Azepines / Q000494:pharmacology; D015153:Blotting, Western; D002135:Calcium-Binding Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D002465:Cell Movement / Q000502:physiology*; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D020868:Gene Silencing / Q000502:physiology; D005901:Glaucoma / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D006874:Hydrostatic Pressure; D007527:Isoenzymes / Q000502:physiology; D009219:Myosin-Light-Chain Kinase / Q000037:antagonists & inhibitors / Q000502:physiology*; D009281:Naphthalenes / Q000494:pharmacology; D009898:Optic Disk / Q000166:cytology* / Q000473:pathology; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D034741:RNA, Small Interfering / Q000235:genetics; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D044465:White People
D001381:Azepines; D002135:Calcium-Binding Proteins; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D009281:Naphthalenes; D034741:RNA, Small Interfering; D018125:Receptors, Transforming Growth Factor beta; C070571:ML 7; D017346:Protein Serine-Threonine Kinases; C499378:MYLK protein, human; D009219:Myosin-Light-Chain Kinase; D000077294:Receptor, Transforming Growth Factor-beta Type II