We recently discovered that a ubiquitous protein, high mobility group box 1 protein (HMGB1), is released by activated macrophages, and functions as a late mediator of lethal systemic inflammation. To elucidate mechanisms underlying the regulation of HMGB1 release, we examined the roles of other cytokines in induction of HMGB1 release in macrophage cell cultures. Macrophage migration inhibitory factor, macrophage-inflammatory protein 1β, and IL-6 each failed to significantly induce the release of HMGB1 even at supraphysiological levels (up to 200 ng/ml). IFN-γ, an immunoregulatory cytokine known to mediate the innate immune response, dose-dependently induced the release of HMGB1, TNF, and NO, but not other cytokines such as IL-1α, IL-1β, or IL-6. Pharmacological suppression of TNF activity with neutralizing Abs, or genetic disruption of TNF expression (TNF knockout) partially (50–60%) inhibited IFN-γ-mediated HMGB1 release. AG490, a specific inhibitor for Janus kinase 2 of the IFN-γ signaling pathway, dose-dependently attenuated IFN-γ-induced HMGB1 release. These data suggest that IFN-γ plays an important role in the regulation of HMGB1 release through a TNF- and Janus kinase 2-dependent mechanism.

Macrophage migration inhibitory factor (MIF) is an immunoregulatory protein that is

Cerebellar granule neurons express a standing outward (background) K+ current (IK,SO) that regulates the resting membrane potential and cell excitability. As several tandem‐pore (2P) K+ channel mRNAs are highly expressed in cerebellar granule cells, we studied whether, and which, 2P K+ channels contribute to IK,SO. IK,SO was highly sensitive to changes in extracellular pH and was partially inhibited by acetylcholine, as reported previously. In cell‐attached patches from cultured cerebellar granule neurons, four types of K+ channels were found to be active when membrane potential was held at −50 mV or +50 mV in symmetrical 140 mm) KCl. Based on single‐channel conductances, gating kinetics and modulation by pharmacological agents and pH, three K+ channels could be considered as functional correlates of TASK‐1, TASK‐3 and TREK‐2, which are members of the 2P K+ channel family. The fourth K+ channel (Type 4) has not been described previously and its molecular correlate is not yet known. Based on the measurement of channel current densities, the Type 2 (TASK‐3) and the Type 4 K+ channels were determined to be the major sources of IK,SO in cultured cerebellar granule neurons. The Type 1 (TASK‐1) and Type 3 (TREK‐2) activities were relatively low throughout cell growth in culture (1‐10 days). Similar to TASK‐1 and TASK‐3, the Type 4 K+ channel was highly sensitive to changes in extracellular pH, showing a 78 % inhibition by changing the extracellular pH from 7.3 to 6.3. The results of this study show that three 2P K+ channels and an additional pH‐sensing K+ channel (Type 4) comprise the IK,SO in cultured cerebellar granule neurons. Our results also show that the high sensitivity of IK,SO to extracellular pH comes from the high sensitivity of Type 2 (TASK‐3) and Type 4 K+ channels.

TASK-1 and TASK-3 are functional members of the tandem-pore K + (K 2P ) channel family, and mRNAs for both channels are expressed together in many brain regions. Although TASK-1 and TASK-3 subunits are able to form heteromers when their complementary RNAs are injected into oocytes, whether functional heteromers are present in the native tissue is not known. Using cultured cerebellar granule (CG) neurones that express mRNAs of both TASK-1 and TASK-3, we studied the presence of heteromers by comparing the sensitivities of cloned and native K + channels to extracellular pH (pH o ) and ruthenium red. The single-channel conductance of TASK-1, TASK-3 and a tandem construct (TASK-1/TASK-3) expressed in COS-7 cells were 14.2 ± 0.4, 37.8 ± 0.7 and 38.1 ± 0.7 pS (-60 mV), respectively. TASK-3 and TASK-1/TASK-3 (and TASK-3/TASK-1) displayed nearly identical single-channel kinetics. TASK-3 and TASK-1/ TASK-3 expressed in COS-7 cells were inhibited by 26 ± 4 and 36 ± 2 %, respectively, when pH o was changed from 8.3 to 7.3. In outside-out patches from CG neurones, the K + channel with single channel properties similar to those of TASK-3 was inhibited by 31 ± 7 % by the same reduction in pH o . TASK-3 and TASK-1/TASK-3 expressed in COS-7 cells were inhibited by 78 ± 7 and 3 ± 4 %, respectively, when 5 µM ruthenium red was applied to outside-out patches. In outside-out patches from CG neurones containing a 38 pS channel, two types of responses to ruthenium red were observed. Ruthenium red inhibited the channel activity by 77 ± 5 % in 42 % of patches (range: 72-82 %) and by 5 ± 4 % (range: 0-9 %) in 58 % of patches. When patches contained more than three 38 pS channels, the average response to ruthenium red was 47 ± 6 % inhibition (n = 5). These electrophysiological studies show that native 38 pS K + channels of the TASK family in cultured CG neurones consist of both homomeric TASK-3 and heteromeric TASK-1/TASK-3.

Purpose: To assess the feasibility of characterizing gene copy number alteration by fluorescence in situ hybridization (FISH) of circulating tumor cells (CTC) isolated using the CellSearch system in patients with progressive castration-resistant metastatic prostate cancer. Experimental Design: We used probe combinations that included the androgen receptor (AR) and MYC genes for FISH analysis of CTC samples collected from 77 men with castrationresistant metastatic prostate cancer. Results: High-level chromosomal amplification of AR was detected in 38% and relative gain of MYC in 56% of samples analyzed. No such abnormalities were detected in samples with CTC counts of <10, reflecting ascertainment difficulty in these lower count samples. Conclusion:The CTC isolated from our patient cohort present a very similar molecular cytogenetic profile to that reported for late-stage tumors and show that FISH analysis of CTC can be a valuable, noninvasive surrogate for routine tumor profiling. That as many as 50% of these patients have substantial amplification of the AR locus indicates that androgen signaling continues to play an important role in late-stage prostate cancer.