Quantitative proteomics: TGFβ₂ signaling in trabecular meshwork cells.
ABSTRACT Transforming growth factor beta 2 (TGFβ₂) is often elevated in the aqueous humor (AH) and trabecular meshwork (TM) of patients with primary open-angle glaucoma (POAG) and appears to contribute to POAG pathogenesis. To better understand TGFβ₂ signaling in the eye, TGFβ₂-induced proteomic changes were identified in cells cultured from the TM, a tissue involved in intraocular pressure (IOP) elevation in glaucoma.
Primary cultures of human TM cells from four donors were treated with or without TGFβ₂ (5 ng/mL) for 48 hours; then cellular protein was analyzed by liquid chromatography-mass spectrometry iTRAQ (isobaric tags for relative and absolute quantitation) technology.
A total of 853 proteins were quantified. TGFβ₂ treatment significantly altered the abundance of 47 proteins, 40 of which have not previously been associated with TGFβ₂ signaling in the eye. More than half the 30 elevated proteins support growing evidence that TGFβ₂ induces extracellular matrix remodeling and abnormal cytoskeletal interactions in the TM. The levels of 17 proteins were reduced, including four cytoskeletal and six regulatory proteins. Both elevated and decreased regulatory proteins implicate TGFβ₂-altered processes involving transcription, translation, and the glutamate/glutamine cycle. Altered levels of eight mitochondrial proteins support TGFβ₂-induced mitochondrial dysfunction in the TM that in POAG could contribute to oxidative damage in the AH outflow pathway, TM senescence, and elevated IOP.
The results expand the repertoire of proteins known to participate in TGFβ₂ signaling, provide new molecular insight into POAG, and establish a quantitative proteomics database for the TM that includes candidate glaucoma biomarkers for future validation studies.
Article: Genetic etiologies of glaucoma.[show abstract] [hide abstract]
ABSTRACT: Glaucoma can be inherited as a mendelian autosomal-dominant or autosomal-recessive trait, or as a complex multifactorial trait. Genetic approaches have helped define the underlying molecular events responsible for some mendelian forms of the disease and have identified the chromosome locations of genes that are likely to contribute to common complex forms. Future directions include the discovery of new glaucoma genes, determining the clinical phenotypes associated with specific genes and mutations, investigating environmental factors that may contribute to the disease, investigating gene-environment interactions and gene-gene interactions, and developing a mutation database that can be used for diagnostic and prognostic testing.Archives of Ophthalmology 02/2007; 125(1):30-7. · 3.71 Impact Factor