26 research outputs found
HMGB1 Translocation in Neurons after Ischemic Insult: Subcellular Localization in Mitochondria and Peroxisomes
High mobility group box-1 (HMGB1), a nonhistone chromatin DNA-binding protein, is released from neurons into the extracellular space under ischemic, hemorrhagic, and traumatic insults. However, the details of the time-dependent translocation of HMGB1 and the subcellular localization of HMGB1 through the release process in neurons remain unclear. In the present study, we examined the subcellular localization of HMGB1 during translocation of HMGB1 in the cytosolic compartment using a middle cerebral artery occlusion and reperfusion model in rats. Double immunofluorescence microscopy revealed that HMGB1 immunoreactivities were colocalized with MTCO1(mitochondrially encoded cytochrome c oxidase I), a marker of mitochondria, and catalase, a marker of peroxisomes, but not with Rab5/Rab7 (RAS-related GTP-binding protein), LC3A/B (microtubule-associated protein 1 light chain 3), KDEL (KDEL amino acid sequence), and LAMP1 (Lysosomal Associated Membrane Protein 1), which are endosome, phagosome, endoplasmic reticulum, and lysosome markers, respectively. Immunoelectron microscopy confirmed that immune-gold particles for HMGB1 were present inside the mitochondria and peroxisomes. Moreover, HMGB1 was found to be colocalized with Drp1 (Dynamin-related protein 1), which is involved in mitochondrial fission. These results revealed the specific subcellular localization of HMGB1 during its release process under ischemic conditions
Tunable Dirac Fermion Dynamics in Topological Insulators
Three-dimensional topological insulators are characterized by insulating bulk
state and metallic surface state involving Dirac fermions that behave as
massless relativistic particles. These Dirac fermions are responsible for
achieving a number of novel and exotic quantum phenomena in the topological
insulators and for their potential applications in spintronics and quantum
computations. It is thus essential to understand the electron dynamics of the
Dirac fermions, i.e., how they interact with other electrons, phonons and
disorders. Here we report super-high resolution angle-resolved photoemission
studies on the Dirac fermion dynamics in the prototypical Bi2(Te,Se)3
topological insulators. We have directly revealed signatures of the
electron-phonon coupling in these topological insulators and found that the
electron-disorder interaction is the dominant factor in the scattering process.
The Dirac fermion dynamics in Bi2(Te3-xSex) topological insulators can be tuned
by varying the composition, x, or by controlling the charge carriers. Our
findings provide crucial information in understanding the electron dynamics of
the Dirac fermions in topological insulators and in engineering their surface
state for fundamental studies and potential applications.Comment: 14 Pages, 4 Figure