Myocilin Regulates Cell Proliferation and Survival
Myocilin, a causative gene for open angle glaucoma, encodes a secreted glycoprotein with poorly understood functions. To gain insight into its functions, we produced a stably transfected HEK293 cell line expressing myocilin under an inducible promoter and compared gene expression profiles between my...
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Veröffentlicht in: | The Journal of biological chemistry 2014-04, Vol.289 (14), p.10155-10167 |
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Zusammenfassung: | Myocilin, a causative gene for open angle glaucoma, encodes a secreted glycoprotein with poorly understood functions. To gain insight into its functions, we produced a stably transfected HEK293 cell line expressing myocilin under an inducible promoter and compared gene expression profiles between myocilin-expressing and vector control cell lines by a microarray analysis. A significant fraction of differentially expressed genes in myocilin-expressing cells was associated with cell growth and cell death, suggesting that myocilin may have a role in the regulation of cell growth and survival. Increased proliferation of myocilin-expressing cells was demonstrated by the WST-1 proliferation assay, direct cell counting, and immunostaining with antibodies against Ki-67, a cellular proliferation marker. Myocilin-containing conditioned medium also increased proliferation of unmodified HEK293 cells. Myocilin-expressing cells were more resistant to serum starvation-induced apoptosis than control cells. TUNEL-positive apoptotic cells were dramatically decreased, and two apoptotic marker proteins, cleaved caspase 7 and cleaved poly(ADP-ribose) polymerase, were significantly reduced in myocilin-expressing cells as compared with control cells under apoptotic conditions. In addition, myocilin-deficient mesenchymal stem cells exhibited reduced proliferation and enhanced susceptibility to serum starvation-induced apoptosis as compared with wild-type mesenchymal stem cells. Phosphorylation of ERK1/2 and its upstream kinases, c-Raf and MEK, was increased in myocilin-expressing cells compared with control cells. Elevated phosphorylation of ERK1/2 was also observed in the trabecular meshwork of transgenic mice expressing 6-fold higher levels of myocilin when compared with their wild-type littermates. These results suggest that myocilin promotes cell proliferation and resistance to apoptosis via the ERK1/2 MAPK signaling pathway.
Background: The physiological function(s) of myocilin, a glaucoma-associated protein, is poorly understood.
Results: Myocilin enhances cell proliferation and survival together with the activation of the ERK signaling pathway. Myocilin-deficient mesenchymal stem cells demonstrate reduced proliferation and survival.
Conclusion: Myocilin participates in the regulation of cell growth and survival.
Significance: This study provides new insight into the role of myocilin in ocular and non-ocular tissues. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1074/jbc.M113.547091 |