TY - JOUR
T1 - Single-cell imaging of retinal ganglion cell apoptosis with a cell-penetrating, activatable peptide probe in an in vivo glaucoma model
AU - Barnett, Edward M.
AU - Zhang, Xu
AU - Maxwell, Dustin
AU - Chang, Qing
AU - Piwnica-Worms, David
PY - 2009/6/9
Y1 - 2009/6/9
N2 - Molecular imaging probes have potential for in vivo identification of apoptosis and other intracellular processes. TcapQ, a cell-penetrating, near-infrared fluorescent peptide probe designed to be optically silent through intramolecular fluorescence quenching and activated by effector caspases, has been previously described and validated in vitro. Herein, using NMDA-induced apoptosis of retinal ganglion cells (RGCs), representing an in vivo rat model of glaucoma, we assessed the ability of TcapQ to image single-cell apoptosis through effector caspase activity. Following intravitreal injection, intracellular TcapQ activation occurred specifically in RGCs, identified individual apoptotic cells, showed a clear dose-response relationship with NMDA, and colocalized with TUNEL labeling in the retina. There was a significant diminution of probe activation following pretreatment with a specific inhibitor of caspase-3. Stereospecificity was also exhibited by the lack of intracellular fluorescence upon administration of the noncleavable isomer, dTcapQ. TcapQ has potential utility in detecting and monitoring single-cell apoptosis in glaucoma in vivo.
AB - Molecular imaging probes have potential for in vivo identification of apoptosis and other intracellular processes. TcapQ, a cell-penetrating, near-infrared fluorescent peptide probe designed to be optically silent through intramolecular fluorescence quenching and activated by effector caspases, has been previously described and validated in vitro. Herein, using NMDA-induced apoptosis of retinal ganglion cells (RGCs), representing an in vivo rat model of glaucoma, we assessed the ability of TcapQ to image single-cell apoptosis through effector caspase activity. Following intravitreal injection, intracellular TcapQ activation occurred specifically in RGCs, identified individual apoptotic cells, showed a clear dose-response relationship with NMDA, and colocalized with TUNEL labeling in the retina. There was a significant diminution of probe activation following pretreatment with a specific inhibitor of caspase-3. Stereospecificity was also exhibited by the lack of intracellular fluorescence upon administration of the noncleavable isomer, dTcapQ. TcapQ has potential utility in detecting and monitoring single-cell apoptosis in glaucoma in vivo.
KW - Caspase
KW - Molecular imaging
KW - Near-infrared fluorescence
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U2 - 10.1073/pnas.0812884106
DO - 10.1073/pnas.0812884106
M3 - Article
C2 - 19458250
AN - SCOPUS:67249095097
SN - 0027-8424
VL - 106
SP - 9391
EP - 9396
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 23
ER -