98 research outputs found
Surface Plasmon Polariton Assisted Optical Switching in Noble Metal Nanoparticle Systems: A Sub-Band Gap Approach
In a proposed book chapter surface plasmon polariton assisted optical
switching in noble metal nanoparticle systems is discussed in the sub-band gap
formalism.Comment: 34 page, 13 figures, Submitted as Book chapter in The Annual Reviews
in Plasmonics, edited by Professor Chris D. Geddes. Springer Scinec
Nonlinear gap junctions enable long-distance propagation of pulsating calcium waves in astrocyte networks
A new paradigm has recently emerged in brain science whereby communications
between glial cells and neuron-glia interactions should be considered together
with neurons and their networks to understand higher brain functions. In
particular, astrocytes, the main type of glial cells in the cortex, have been
shown to communicate with neurons and with each other. They are thought to form
a gap-junction-coupled syncytium supporting cell-cell communication via
propagating Ca2+ waves. An identified mode of propagation is based on
cytoplasm-to-cytoplasm transport of inositol trisphosphate (IP3) through gap
junctions that locally trigger Ca2+ pulses via IP3-dependent Ca2+-induced Ca2+
release. It is, however, currently unknown whether this intracellular route is
able to support the propagation of long-distance regenerative Ca2+ waves or is
restricted to short-distance signaling. Furthermore, the influence of the
intracellular signaling dynamics on intercellular propagation remains to be
understood. In this work, we propose a model of the gap-junctional route for
intercellular Ca2+ wave propagation in astrocytes showing that: (1)
long-distance regenerative signaling requires nonlinear coupling in the gap
junctions, and (2) even with nonlinear gap junctions, long-distance
regenerative signaling is favored when the internal Ca2+ dynamics implements
frequency modulation-encoding oscillations with pulsating dynamics, while
amplitude modulation-encoding dynamics tends to restrict the propagation range.
As a result, spatially heterogeneous molecular properties and/or weak couplings
are shown to give rise to rich spatiotemporal dynamics that support complex
propagation behaviors. These results shed new light on the mechanisms
implicated in the propagation of Ca2+ waves across astrocytes and precise the
conditions under which glial cells may participate in information processing in
the brain.Comment: Article: 30 pages, 7 figures. Supplementary Material: 11 pages, 6
figure
Two Cellular Protein Kinases, DNA-PK and PKA, Phosphorylate the Adenoviral L4-33K Protein and Have Opposite Effects on L1 Alternative RNA Splicing
Accumulation of the complex set of alternatively processed mRNA from the adenovirus major late transcription unit (MLTU) is subjected to a temporal regulation involving both changes in poly (A) site choice and alternative 3′ splice site usage. We have previously shown that the adenovirus L4-33K protein functions as an alternative splicing factor involved in activating the shift from L1-52,55K to L1-IIIa mRNA. Here we show that L4-33K specifically associates with the catalytic subunit of the DNA-dependent protein kinase (DNA-PK) in uninfected and adenovirus-infected nuclear extracts. Further, we show that L4-33K is highly phosphorylated by DNA-PK in vitro in a double stranded DNA-independent manner. Importantly, DNA-PK deficient cells show an enhanced production of the L1-IIIa mRNA suggesting an inhibitory role of DNA-PK on the temporal switch in L1 alternative RNA splicing. Moreover, we show that L4-33K also is phosphorylated by protein kinase A (PKA), and that PKA has an enhancer effect on L4-33K-stimulated L1-IIIa splicing. Hence, we demonstrate that these kinases have opposite effects on L4-33K function; DNA-PK as an inhibitor and PKA as an activator of L1-IIIa mRNA splicing. Taken together, this is the first report identifying protein kinases that phosphorylate L4-33K and to suggest novel regulatory roles for DNA-PK and PKA in adenovirus alternative RNA splicing
Mediation of growth factor induced DNA synthesis and calcium mobilization by Gq and Gi2.
Movement of the free catalytic subunit of cAMP-dependent protein kinase into and out of the nucleus can be explained by diffusion.
Synthesis of cell-impermeable Cl-sensitive fluorescent indicators with improved sensitivity and optical properties
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