AMP-activated protein kinase regulates intraocular pressure, extracellular matrix, and cytoskeleton in trabecular meshwork.

ABSTRACT: In this study, we investigate how adenosine monophosphate-activated protein kinase (AMPK) affects extracellular matrix (ECM) and cellular tone in the trabecular meshwork (TM), and examine how deletion of its catalytic ?2 subunit affects IOP and aqueous humor clearance in mice.Human TM tissue was examined for expression of AMPK?1 and AMPK?2, genomically distinct isoforms of the AMPK catalytic subunit. Primary cultured human TM cells were treated for 24 hours with the AMPK activator 5-amino-1-?-Dffff-ribofuranosyl-imidazole-4-carboxamide (AICAR), under basal or TGF-?2 stimulatory conditions. Conditioned media (CM) was probed for secreted protein acidic and rich in cysteine (SPARC), thrombospondin-1 (TSP-1), and ECM proteins, and cells were stained for F-actin. Cells underwent adenoviral infection with a dominant negative AMPK? subunit (ad.DN.AMPK?) and were similarly analyzed. Intraocular pressure, central corneal thickness (CCT), and aqueous clearance were measured in AMPK?2-null and wild-type (WT) mice.Both AMPK?1 and AMPK?2 are expressed in TM. AICAR activated AMPK? and suppressed the expression of various ECM proteins under basal and TGF-?2 stimulatory conditions. AICAR decreased F-actin staining and increased the phospho-total RhoA ratio (Ser188). Transforming growth factor-?2 transiently dephosphorylated AMPK?. Infection with ad.DN.AMPK? upregulated various ECM proteins, decreased the phospho-total RhoA ratio, and increased F-actin staining. AMPK?2-null mice exhibited 6% higher IOP and decreased aqueous clearance compared with WT mice, without significant differences in CCT or angle morphology.Collectively, our data identify AMPK as a critical regulator of ECM homeostasis and cytoskeletal arrangement in the TM. Mice that are AMPK?2-null exhibit higher IOPs and decreased aqueous clearance than their WT counterparts.

SUBMITTER: Chatterjee A 

PROVIDER: S-EPMC4023495 | biostudies-literature | 2014 Apr

REPOSITORIES: biostudies-literature