Neuron
Vesicular trafficatng
Biochem Biophys Res Commun. 2000 Sep 24;276(2):626-32. Doc2gamma, a third isoform of double C2 protein, lacking
calcium-dependent phospholipid binding activity. ·
Fukuda M, Mikoshiba
K. Laboratory for Developmental
Neurobiology, Brain Science Institute, RIKEN, 2-1 Hirosawa,
Wako, Saitama, 351-0198, The Doc2 (double C2) family consists of two isoforms (Doc2alpha and Doc2beta) characterized by an
N-terminal Munc13-1 interacting domain (Mid) and two C2 domains that
interact with Ca(2+) and phospholipid
at the C-terminus. This Ca(2+)-binding property is
thought to be important to the regulation of neurotransmitter release. In
this paper, we report a third isoform of mouse
Doc2, named Doc2gamma. Doc2gamma also contains a putative Mid domain and two C2 domains, and it is 45.6 and 43.2%
identical to mouse Doc2alpha and Doc2beta, respectively, at the amino acid
level. In contrast to the other Doc2 isoforms,
the C2 domains of Doc2gamma impair Ca(2+)-dependent
phospholipid binding activity. The highest expression
of Doc2gamma mRNA was found in the heart, but occurs ubiquitously, the same
as Doc2beta. These findings indicate that Doc2gamma may also function as an
effector for Munc13-1 and that it may be involved
in the regulation of vesicular trafficking. Copyright
2000 Academic Press. PMID: 11027523 [PubMed -
indexed for MEDLINE] Cell Calcium. 2006 Jan;39(1):85-93. Epub 2005 Nov 21. Calcium concentration
threshold and translocation kinetics of EGFP-DOC2B expressed in cultured Aplysia neurons. ·
Malkinson
G, Spira
ME. Department of Neurobiology, The Life Sciences
Institute, The Hebrew University of Jerusalem, Jerusalem 91904, Israel. The double C2 domain protein family (DOC2) is
characterized by two calcium-binding domains (C2). Upon binding to calcium,
the affinity of the protein to phospholipids is significantly increased,
leading to translocation of the protein from the cytosol
to the plasma membrane. These properties, and the binding domain of DOC2B
to Munc13, suggested that DOC2B could play a role in augmentation and potentiation of synaptic release. Nevertheless, the
level of the free intracellular calcium concentration ([Ca(2+)](i)) which triggers its translocation under in vivo
conditions, is not known. Using cultured Aplysia
neurons that express rat EGFP-DOC2B, we found that the [Ca(2+)](i) increment necessary to induce EGFP-DOC2B
translocation is approximately 200 nM in the bulk
of the cytoplasm. The rate of EGFP-DOC2B recruitment to the plasma membrane
is slower than the [Ca(2+)](i)
elevation rate, while the detachment of EGFP-DOC2B from it is faster than
the calcium removal. The extent of EGFP-DOC2B translocation to the plasma
membrane reflects local submembrane [Ca(2+)](i). Our observations are consistent with the
view that DOC2B can participate in the regulation of neurotransmitter
release. It should be noted that EGFP-DOC2B could be used as a tool to map
sub-membrane calcium dynamics under physiological conditions. PMID: 16305808 [PubMed -
indexed for MEDLINE] J Neurochem. 2006 May;97(3):818-33.
Epub 2006 Mar 3. DOC2A and DOC2B are
sensors for neuronal activity with unique calcium-dependent and kinetic
properties. ·
Groffen
AJ, Friedrich R,
Brian EC, Ashery
U, Verhage
M. Department of Functional
Genomics, Center for Neurogenomics and Cognition
Research, Vrije Universiteit
(VU) and VU Medical Centre, Elevation of the intracellular calcium concentration
([Ca2+]i) to levels
below 1 microm alters synaptic transmission and
induces short-term plasticity. To identify calcium sensors involved in this
signalling, we investigated soluble C2 domain-containing
proteins and found that both DOC2A and DOC2B are modulated by submicromolar calcium levels. Fluorescent-tagged DOC2A
and DOC2B translocated to plasma membranes after
[Ca2+]i elevation. DOC2B
translocation preceded DOC2A translocation in cells co-expressing both isoforms. Half-maximal translocation occurred at 450
and 175 nm[Ca2+]i for
DOC2A and DOC2B, respectively. This large difference in calcium sensitivity
was accompanied by a modest kinetic difference (halftimes, respectively,
2.6 and 2.0 s). The calcium sensitivity of DOC2 isoforms
can be explained by predicted topologies of their C2A domains.
Consistently, neutralization of aspartates D218
and D220 in DOC2B changed its calcium affinity. In neurones,
both DOC2 isoforms were reversibly recruited to
the plasma membrane during trains of action potentials. Consistent with its
higher calcium sensitivity, DOC2B translocated at
lower depolarization frequencies. Styryl dye
uptake experiments in hippocampal neurones suggest that the overexpression
of mutated DOC2B alters the synaptic activity. We conclude that both DOC2A
and DOC2B are regulated by neuronal activity, and hypothesize that their
calcium-dependent translocation may regulate synaptic activity. PMID: 16515538 [PubMed -
indexed for MEDLINE] Chronic
exposure to TNF-alpha increases airway mucus gene expression in vivo. Am
J Respir Crit Care
Med. 2005 Feb 15;171(4):305-14. Epub 2004 Nov 5. Zhonghua Jie He He Hu Xi Za Zhi. 2004 Sep;27(9):585-8. Differential Regulation of CD40-Mediated TNF
Receptor-Associated Factor Degradation in B Lymphocytes. B Cell Maturation Antigen, the Receptor
for a Proliferation-Inducing Ligand and B
Cell-Activating Factor of the TNF Family, Induces Antigen Presentation in B
Cells. ICAM-1 gene expression in endothelial cells: Effects on the
inhibition of STAT3 phosphorylation.
Busse PJ, Zhang TF, Srivastava K,
Lin BP, Schofield B,
Sealfon SC,
Li XM.
Division of Clinical Immunology,
BACKGROUND: Hypersecretion of mucus plays an
important role in the pathogenesis and severity of asthma. The primary
proteins in mucus are mucin glycoproteins;
MUC-5AC is the primary airway mucin gene. The
calcium chloride-activated channel gene hCLCA1 (gob-5 in the mouse) has
been suggested to increase MUC-5AC gene expression, and both are increased
in asthmatic patients and murine models.
TNF-alpha increases the expression of these genes in vitro but has not been
investigated in vivo. OBJECTIVE: We sought to determine whether TNF-alpha
increases gene expression of gob-5 and MUC-5AC and induces
mucus cell metaplasia in vivo. METHODS: Naive
BALB/c mice received 50 ng of recombinant murine TNF-alpha (rmTNF-alpha)
intratracheally daily for 1, 2, or 3 weeks;
another group received the same dose of intratracheal
rmTNF-alpha daily for 3 weeks and then
alternate-day treatment for 3 additional weeks (total of 6 weeks). AKR mice
received 50 ng of rmTNF-alpha
intratracheally for 3 or 6 weeks daily. Naive nontreated mice were used as control animals. Airway
gene products for gob-5 and MUC-5AC were determined by means of real-time
PCR. Lung tissue sections were stained with periodic acid-Schiff/Alcian blue to assess mucus cell metaplasia.
RESULTS: rmTNF-alpha significantly increased gene
expression of airway gob-5 and MUC-5AC after 2 weeks in the BALB/c mice.
There was noticeable mucus staining in all mice treated for at least 3
weeks with TNF-alpha and in 80% of the mice receiving 2 weeks of treatment.
After 3 weeks of treatment, the AKR mice also showed increased gob-5
expression. CONCLUSIONS: This study demonstrates for the first time that
TNF-alpha alone in vivo is sufficient to increase airway mucus gene
expression in 2 murine strains.
PMID: 16337454 [PubMed - indexed for MEDLINE]
Metalloproteinases mediate mucin 5AC
expression by epidermal growth factor receptor activation.
Deshmukh
HS, Case LM, Wesselkamper
SC, Borchers
MT, Martin LD,
Shertzer
HG, Nadel
JA, Leikauf
GD.
Chronic obstructive pulmonary disease is marked by alveolar enlargement and
excess production of airway mucus. Acrolein, a
component of cigarette smoke, increases mucin 5AC
(MUC5AC), a prevalent airway mucin in NCI-H292
cells by transcriptional activation, but the signal transduction pathways
involved in acrolein-induced MUC5AC expression
are unknown. Acrolein depleted cellular
glutathione at doses of 10 muM or greater, higher
than those sufficient (0.03 muM) to increase
MUC5AC mRNA, suggesting that MUC5AC expression was independent of oxidative
stress. In contrast, acrolein increased MUC5AC
mRNA levels by phosphorylating epidermal growth
factor receptor (EGFR) and mitogen-activated
protein kinase 3/2, or MAPK 3/2(ERK1/2). Pretreating the cells with an EGFR-neutralizing
antibody, or a metalloproteinase inhibitor, decreased the acrolein-induced MUC5AC mRNA increase. Small,
interfering RNA directed against ADAM17 or MMP9 inhibited the acrolein-induced MUC5AC mRNA increase. Acrolein increased the release and subsequent
activation of pro-MMP9. Acrolein increased MMP9
and decreased tissue inhibitor of metalloproteinase 3 (TIMP3), an
endogenous inhibitor of ADAM17, transcripts. Together, these data suggest
that acrolein induces MUC5AC expression via an
initial ligand-dependent activation of EGFR
mediated by ADAM17 and MMP9. In addition, a prolonged effect of acrolein may be mediated by altering MMP9 and TIMP3
transcription.
PMID: 15531749 [PubMed - indexed for MEDLINE]
[Expression of epidermal growth factor receptor
and MUC5AC on human airway with chronic obstructive pulmonary disease]
[Article in Chinese]
Mao L, Bai
CX, Zhang M, Wang YH, Chen J.
Department of Pulmonary Diseases,
OBJECTIVE: To determine the relationship between epidermal growth factor
receptor (EGFR) expression and mucin 5AC (MUC5AC)
synthesis in human airways with chronic obstructive pulmonary disease
(COPD). METHODS: Lung specimens were obtained from 38 patients who were
undergoing lobectomy, and the samples were taken
from areas remote to the lesion. EGFR and MUC5AC protein expression were
examined using immunohistochemical analysis and
Western blot in peripheral airways (less than 2 mm in diameter) from 16
subjects with COPD, 10 subjects with a history of more than 30 pack-year
smoking and 12 nonsmokers or exsmokers (0 - 10
pack-year smoker). RESULTS: Weak EGFR protein signals were detected in the
lungs of the controls (2.01 +/- 1.02) in comparison with stronger signal in
the COPD patients (4.62 +/- 1.65, P < 0.01) and the smokers (4.89 +/-
1.89, P < 0.01). EGFR immunoreactivity was
observed mainly in goblet cells in the controls, the percentage of positive
cell being 71.1% +/- 14.3%, which was higher than those in COPD (21.1% +/-
8.6%) or in the smoker (21.9% +/- 9.7%) airways. In contrast, COPD or
smoker airways showed more expression of EGFR which expressed mainly in
basal cells (42.9% +/- 14.2%, 52.1% +/- 13.5%, respectively) than that in
the control airways (23.7% +/- 9.5%, P < 0.01). However there was no significant differences in EGFR expression and
location in peripheral airways between COPD patients and smokers (P >
0.05). There was significant positive correlation between EGFR immunoreactivity and the area of the MUC5AC positive
staining in all subjects (r = 0.877 4, P < 0.001). CONCLUSION: It is
suggested that EGFR activation is involved in mucin
expression in COPD airways.
PMID: 15498267 [PubMed - indexed for MEDLINE]
Moore
CR, Bishop GA.
Interdisciplinary Graduate Program in Immunology.
Engagement of CD40 on murine B cells by its ligand CD154 induces the binding of TNFR-associated
factors (TRAFs) 1, 2, 3, and 6, followed by the
rapid degradation of TRAFs 2 and 3. TRAF
degradation occurs in response to signaling by other TNFR superfamily members, and is likely to be a normal
regulatory component of signaling by this receptor family. In this study,
we found that receptor-induced TRAF degradation limits TRAF2-dependent CD40
signals to murine B cells. However, TRAFs 1 and 6 are not degraded in response to CD40
engagement, despite their association with CD40. To better understand the
mechanisms underlying differential TRAF degradation, mixed protein domain
TRAF chimeras were analyzed in murine B cells.
Chimeras containing the TRAF2 zinc (Zn) domains induced effective
degradation, if attached to a TRAF domain that binds to the PXQXT motif of
CD40. However, the Zn domains of TRAF3 and TRAF6 could not induce
degradation in response to CD40, regardless of the TRAF domains to which
they were attached. Our data indicate that TRAF2 serves as the master
regulator of TRAF degradation in response to CD40 signaling, and this
function is dependent upon both the TRAF Zn domains and receptor binding
position.
PMID: 16148124 [PubMed - in process]
Yang M, Hase
H, Legarda-Addison
D, Varughese
L, Seed B, Ting AT.
B cell maturation Ag (BCMA), a member of the TNFR superfamily
expressed on B cells, binds to a proliferation-inducing ligand
(APRIL) and B cell-activating factor of the TNF family (BAFF) but the
specific B cell responses regulated by BCMA remain unclear. This study
demonstrates that ligation of A20 B cells transfected with BCMA induces the expression of CD40,
CD80/B7-1, CD86/B7-2, MHC class II, and CD54/ICAM-1, which subsequently
enhances the presentation of OVA peptide Ag to DO11.10 T cells. BCMA
expression in murine splenic
B cells can be induced with IL-4 and IL-6, allowing subsequent treatment
with APRIL or agonist anti-BCMA to similarly induce Ag presentation. A
comparative analysis of hybrid receptors of TNFR2 fused to the cytoplasmic domains of APRIL/BAFF receptors found that
only BCMA, but not transmembrane activator and
calcium-modulator and cyclophilin ligand interactor or BAFF-R,
is capable of activating Ag presentation. Although all three receptors can
trigger NF-kappaB signaling, only BCMA activates
the JNK pathway conferring on BCMA the specific ability to activate this Ag
presentation response.
PMID: 16116167 [PubMed - in process]
Resveratrol suppresses IL-6-induced
Wung
BS, Hsu MC, Wu CC, Hsieh CW.
Department of Applied Microbiology,
Resveratrol, a polyphenolic
phytoaxelin present in red wine, has been
suggested to protect against atherosclerosis and cardiovascular disease
because of its antioxidant effects. Intercellular adhesion molecule
(ICAM-1), induced by cytokines, has been hypothesized to play a role in the
early events during atherosclerosis. In this study we tested the effects of
resveratrol upon both IL-6-induced ICAM-1 gene
expression and its underlying signaling pathways in endothelial cells (ECs). Resveratrol was found
to inhibit both TNFalpha- and IL-6-induced ICAM-1
gene expression at the promoter, transcriptional and protein levels. Resveratrol also abrogates the tyr705 phosphorylation of STAT3 in IL-6-treated ECs, in a dose- and time-dependent manner. Although quercetin had similar effects, resveratrol
showed higher inhibitory properties following 2-4 h pretreatments. Resveratrol has been shown to induce the activity of
endothelial nitric oxide synthase (eNOS) and increase NO production. Consistent with this,
the treatment of ECs with a NO donor (SNAP)
reduces IL-6-induced STAT3 phosphorylation.
Conversely, exposure of ECs to a NOS inhibitor
reversed the effects of resveratrol upon
IL-6-induced STAT3 phosphorylation. Furthermore, ECs transfected with
constitutively active Rac1 (RacV12) showed increases in ICAM-1 promoter
activity, intracellular reactive oxygen species (ROS) levels and STAT3 phosphorylation, and these increases were attenuated by
resveratrol treatment. In summary, we demonstrate
for the first time that resveratrol inhibits
IL-6-induced ICAM-1 gene expression, in part, by interfering with Rac-mediated pathways via the attenuation of STAT3 phosphorylation. This study therefore provides
important new insights that may contribute to the proposed beneficial effects
of resveratrol in endothelial responses to
cytokines during inflammation.
PMID: 16150460 [PubMed - as supplied by
publisher]