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Rasiah Pratheepa kumari, Nikolai Skiba, Vasanth Rao; The Role of BASP-1 and MARCKS in Lens Cytoarchitecture and Function. Invest. Ophthalmol. Vis. Sci. 2016;57(12):3072.
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© 2017 Association for Research in Vision and Ophthalmology.
To explore the role of lens calmodulin and Phosphatidylinositol 4, 5-bisphosphate (PIP2) binding, and Protein Kinase C substrates known to regulate membrane organization, cell adhesive interactions and cortical cytoskeletal organization, including Brain acid soluble protein (BASP-1), Myristoylated alanine-rich C-kinase substrate (MARCKS) and Growth associated protein (GAP-43), in lens morphogenesis, cytoarchitecture, growth and function.
The acid soluble fraction derived from both mouse and human lenses, and porcine lens fiber cell membrane rafts were analyzed by mass spectrometry and immunoblot analyses. Distribution of BASP-1 and MARCKS in the developing and mature mouse lens was evaluated by immunofluorescence analysis. Lens phenotype was examined in MARCKS null mouse embryos by histological analysis.
BASP-1 was found to be most abundant protein relative to MARCKS and GAP-43 in the lens tissue based on cDNA microarray, mass spectrometry and immunoblot analyses. BASP-1 was also found to be one of the prominent components of lens membrane rafts. MARCKS was detected in the lens by both mass spectrometry and cDNA microarray analyses. BASP-1 was detected in both membrane and cytosolic fractions of mouse lens and distributed intensively to the lens fiber cell membrane relative to the epithelium. BASP-1 showed colocalization with Ankyrin-B and NrCAM but not with β-actin and N-cadherin in the mouse lens fibers. MARCKS was distributed throughout the lens including both epithelium and fiber cells. MARCKS null mice, which die before birth, did not exhibit overt abnormalities in embryonic (E17.5) lens morphogenesis, however, the primary lens fibers exhibited subtle disorganization, swelling and posterior sutural abnormality. The BASP-1 null mice are being re-derived to determine the role of BASP-1 in lens growth and function.
These initial observations reveal that of the various calmodulin binding and PIP2 sequestering PKC substrates evaluated, BASP-1 is the predominant protein expressed in lens tissue, distributing intensely to the fiber cells. BASP-1’s prominent presence in PIP2 enriched lens fiber cell detergent-resistant membrane rafts suggests its importance in membrane microdomain and cytoskeletal organization.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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