Browsing by Author "Hsu, JM"

Now showing 1 - 2 of 2

Identification of V23RalA-Ser(194) as a critical mediator for aurora-A-induced cellular motility and transformation by small pool expression screening
(2005-03-11)
Wu, JC
;
Chen, TY
;
Yu, CTR
;
Tsai, SJ
;
Hsu, JM
Human Aurora kinases have three gene family members: Aurora-A, Aurora-B, and Aurora-C. It is not yet established what the specificity of these kinases are and what signals relayed by their reactions. Therefore, we employed small pool expression screening to search for downstream substrates of Aurora-A. Interestingly, all of the identified Aurora-A substrates were resistant to serve as substrates for Aurora-B or Aurora-C, suggesting that these Aurora family members may have distinct substrate specificity for propagation of diverse signaling pathways, even though they share a conserved catalytic kinase domain. Of the candidate substrates, Aurora-A could increase the functional activity of RalA. Mutational analysis revealed that RalA-Ser(194) was the phosphorylation site for Aurora-A. Ectopic expression of V23RalA-WT could enhance collagen I-induced cell migration and anchorage-independent growth in Madin-Darby canine kidney (MDCK) Aurora-A stable cell lines. In contrast, overexpression of V23RalA-S194A in MDCK Aurora-Astable cell lines abolished the intrinsic migration and transformation abilities of Aurora-A. To our knowledge, this is the first systematic search for the downstream substrates of Aurora-A kinase. Moreover, these results support the notion that Aurora-A may act in concert with V23RalA through protein phosphorylation on Ser(194) to promote collagen I-induced cell motility and anchorage-independent growth in MDCK epithelial cells.
In-line fiber polarization selector and intensity modulator
(1997)
Chen, TJ
;
Hsu, JM
;
Chen, SH
;
光電工程學系
;
Department of Photonics
Liquid-crystal-based fiber components that exploit the high birefringence and electrooptic effect of liquid crystals, are versatile. A single-mode fiber enclosed with planar-aligned liquid crystals is reported on in this paper. The fiber was etched nearly to its core. The output light was exercised through the evanescent field coupling between the fiber and surrounding liquid crystals. To achieve an effective access to the evanescent field, the etch depth was studied first. When the fiber was etched to 10-mu m diameter, obvious light leakage occurred. Once the electric field was switched on, the polarization selection and intensity modulation were examined. A theoretical description of the optical characteristics were also given.