Research Faculty

Shigeo Tamiya, Ph.D.

Assistant Professor
Department of Ophthalmology and Visual Sciences

CONTACT INFORMATION:

301 E. Muhammad Ali Boulevard, Louisville KY 40202
Telephone: 502-852-0402
E-mail: shigeo.tamiya@louisville.edu

EDUCATION:

RESEARCH INTERESTS:

My research is focused on identifying mechanisms involved in the development of ocular fibrotic complications; understanding the role of epithelial ion transporters in ocular physiology.

Fibrosis involving epithelial cells starts with an injury to the epithelium by various factors. Upon injury, epithelial cells undergo epithelial-mesenchymal transition (EMT), a biological process in which stationary epithelial cells lose their apicobasal polarity and assume a migratory mesenchymal phenotype. In many cases, the cells further transform into myofibroblasts, a highly contractile cell type that is involved in fibrotic scar tissue formation. My long-term goal has been to understand the molecular mechanisms involved in EMT and associated fibrotic changes in order to prevent fibrotic complications/diseases by pharmacological intervention. There are two ocular fibrotic disorders that EMT and/or myofibroblast transformation has been shown to play a critical role: posterior capsule opacification, which involves lens epithelial cells following cataract surgery, and proliferative vitreoretinopathy (PVR), in which retinal pigment epithelial (RPE) cells play a major role in the development of a fibrotic proliferative membrane following ocular trauma or retinal detachment. Current focus is on identifying molecules involved in EMT of RPE cells in relation to PVR. We have established an in vitro model that is well suited for studying EMT of RPE cells.

Maintenance of intracellular ion levels, mediated by ion transporters and channels, is vital for normal cell function. Deregulation of ion homeostasis often results in pathological changes. For example, it is well-established that ion homeostasis is disturbed in majority of cataracts, which have abnormally high sodium and calcium concentration while the potassium concentration is significantly reduced. I am interested in the regulation of sodium and calcium concentration as well as pH in ocular epithelial cells.

PUBLICATIONS:

(15 selected publications from 18)

1. Tamiya S, Liu L, Kaplan HJ.; Loss of cell-cell contact initiates epithelial-mesenchymal transition and proliferation of retinal pigment epithelial cells. Invest Ophthalmol Vis Sci. 2009 Dec 30. [Epub ahead of print]PMID: 20042656 [PubMed - as supplied by publisher]
2. Liu Y, Ye F, Li Q, Tamiya S, Darling DS, Kaplan HJ, Dean DC.; Zeb1 represses Mitf and regulates pigment synthesis, cell proliferation, and epithelial morphology. Invest Ophthalmol Vis Sci. 2009 Nov;50(11):5080-8. Epub 2009 Jun 10.PMID: 19515996 [PubMed - indexed for MEDLINE]
3. Gozdz A, Vashishta A, Kalita K, Szatmari E, Zheng JJ, Tamiya S, Delamere NA, Hetman M.; Cisplatin-mediated activation of extracellular signal-regulated kinases 1/2 (ERK1/2) by inhibition of ERK1/2 phosphatases.J Neurochem. 2008 Sep;106(5):2056-67. Epub 2008 Jul 4.PMID: 18665890 [PubMed - indexed for MEDLINE]
4. Shahidullah M, Tamiya S, Delamere NA.; Primary culture of porcine nonpigmented ciliary epithelium. Curr Eye Res. 2007 Jun;32(6):511-22.PMID: 17612967 [PubMed - indexed for MEDLINE]
5. Tamiya S, Okafor MC, Delamere NA.; Purinergic agonists stimulate lens Na-K-ATPase-mediated transport via a Src tyrosine kinase-dependent pathway. Am J Physiol Cell Physiol. 2007 Aug;293(2):C790-6. Epub 2007 May 23.PMID: 17522142 [PubMed - indexed for MEDLINE]
6. Tamiya S, Delamere NA.; The influence of sodium-calcium exchange inhibitors on rabbit lens ion balance and transparency. Exp Eye Res. 2006 Nov;83(5):1089-95. Epub 2006 Jul 12.PMID: 16839544 [PubMed - indexed for MEDLINE]
7. Tamiya S, Delamere NA.; Studies of tyrosine phosphorylation and Src family tyrosine kinases in the lens epithelium. Invest Ophthalmol Vis Sci. 2005 Jun;46(6):2076-81.PMID: 15914626 [PubMed - indexed for MEDLINE]
8. Maidment JM, Duncan G, Tamiya S, Collison DJ, Wang L, Wormstone IM.; Regional differences in tyrosine kinase receptor signaling components determine differential growth patterns in the human lens. Invest Ophthalmol Vis Sci. 2004 May;45(5):1427-35. PMID: 15111598 [PubMed - indexed for MEDLINE]
8. Wormstone IM, Tamiya S, Eldred JA, Lazaridis K, Chantry A, Reddan JR, Anderson I, Duncan G.; Characterisation of TGF-beta2 signalling and function in a human lens cell line. Exp Eye Res. 2004 Mar;78(3):705-14.PMID: 15106950 [PubMed - indexed for MEDLINE]
9. Tamiya S, Dean WL, Paterson CA, Delamere NA.; Regional distribution of Na,K-ATPase activity in porcine lens epithelium. Invest Ophthalmol Vis Sci. 2003 Oct;44(10):4395-9.PMID: 14507885 [PubMed - indexed for MEDLINE]
10. Okafor M, Tamiya S, Delamere NA.; Sodium-calcium exchange influences the response to endothelin-1 in lens epithelium. Cell Calcium. 2003 Sep;34(3):231-40.PMID: 12887970 [PubMed - indexed for MEDLINE]
11. Wormstone IM, Tamiya S, Anderson I, Duncan G.; TGF-beta2-induced matrix modification and cell transdifferentiation in the human lens capsular bag. Invest Ophthalmol Vis Sci. 2002 Jul;43(7):2301-8.PMID: 12091431 [PubMed - indexed for MEDLINE]
12. Wormstone IM, Del Rio-Tsonis K, McMahon G, Tamiya S, Davies PD, Marcantonio JM, Duncan G.; FGF: an autocrine regulator of human lens cell growth independent of added stimuli.Invest Ophthalmol Vis Sci. 2001 May;42(6):1305-11. Erratum in: Invest Ophthalmol Vis Sci 2001 Jul;42(8):1690. PMID: 11328744 [PubMed - indexed for MEDLINE]
13. Tamiya S, Wormstone IM, Marcantonio JM, Gavrilovic J, Duncan G.; Induction of matrix metalloproteinases 2 and 9 following stress to the lens. Exp Eye Res. 2000 Dec;71(6):591-7.PMID: 11095911 [PubMed - indexed for MEDLINE]
14. Wormstone IM, Tamiya S, Marcantonio JM, Reddan JR; Hepatocyte growth factor function and c-Met expression in human lens epithelial cells. Invest Ophthalmol Vis Sci. 2000 Dec;41(13):4216-22.PMID: 11095618 [PubMed - indexed for MEDLINE]