Antibody to Propionibacterium acnes (P.acnes) in guinea pigs with pulmonary granulomatosis

P.acnesを皮内前感作した後、P.acnes菌体壁成分をimcomplete Freund's adjuvantと共に気管内に投与して作製した実験的肺肉芽腫症モルモットにおける抗P.acnes抗体について検討した。気管支肺胞洗浄液中抗P.acnes抗体価は気管内投与後1週目ピークを示し2週目までは上昇が認められ、4週目では気管内投与前の値に復した。この経過は肺胞内リンパ球数の変動と軌を一にしており、抗体価とリンパ球数の間には正の強い相関が認められた。血清中の抗P.acnes抗体価は1週目に低下が認められ、2週以後に徐々に回復して4週以後は元に戻った。P.acnesの気管内投与により血清中の抗体は肺へと移行し、リンパ球浸潤による胞隔炎、更には類上皮細胞肉芽腫の形成にP.acnesの関与を示すものであった。In guinia pig models of P.ances induced pulmonary granulomatosis, anti-P.acnes antibody activity in bronchoalveolar lavage fluid peaked at 1 week after the endotracheally injection and decreased progressively, attaining control animal value by 4 weeks. The change of lymphocyte counts paralleled the change of anti-P.acnes antibody activity levels in bronchoalveolar fluids. Furthermore, the degree of granuloma formation in the lung paralleled the rise of anti-P.acnes antibody activity level. This data suggests that the anti-P.acnes antibody play a central role in the induction of lymphocyte alveolitis in experimental pulmonary granulomatosis

Differential β-arrestin2 requirements for constitutive and agonist-induced internalization of the CB1 cannabinoid receptor

CB1 cannabinoid receptor (CB1R) undergoes both constitutive and agonist-induced internalization, but the underlying mechanisms of these processes and the role of beta-arrestins in the regulation of CB1R function are not completely understood. In this study, we followed CB1R internalization using confocal microscopy and bioluminescence resonance energy transfer measurements in HeLa and Neuro-2a cells. We found that upon activation CB1R binds beta-arrestin2 (beta-arr2), but not beta-arrestin1. Furthermore, both the expression of dominant-negative beta-arr2 (beta-arr2-V54D) and siRNA-mediated knock-down of beta-arr2 impaired the agonist-induced internalization of CB1R. In contrast, neither beta-arr2-V54D nor beta-arr2-specific siRNA had a significant effect on the constitutive internalization of CB1R. However, both constitutive and agonist-induced internalization of CB1R were impaired by siRNA-mediated depletion of clathrin heavy chain. We conclude that although clathrin is required for both constitutive and agonist-stimulated internalization of CB1R, beta-arr2 binding is only required for agonist-induced internalization of the receptor suggesting that the molecular mechanisms underlying constitutive and agonist-induced internalization of CB1R are different

Disturbance of cerebellar synaptic maturation in mutant mice lacking BSRPs, a novel brain-specific receptor-like protein family

AbstractBy DNA cloning, we have identified the BSRP (brain-specific receptor-like proteins) family of three members in mammalian genomes. BSRPs were predominantly expressed in the soma and dendrites of neurons and localized in the endoplasmic reticulum (ER). Expression levels of BSRPs seemed to fluctuate greatly during postnatal cerebellar maturation. Triple-knockout mice lacking BSRP members exhibited motor discoordination, and Purkinje cells (PCs) were often innervated by multiple climbing fibers with different neuronal origins in the mutant cerebellum. Moreover, the phosphorylation levels of protein kinase Cα (PKCα) were significantly downregulated in the mutant cerebellum. Because cerebellar maturation and plasticity require metabotropic glutamate receptor signaling and resulting PKC activation, BSRPs are likely involved in ER functions supporting PKCα activation in PCs

Regulation of cell survival by sphingosine-1-phosphate receptor S1P1 via reciprocal ERK-dependent suppression of bim and PI-3-kinase/protein kinase C-mediated upregulation of Mcl-1

Although the ability of bioactive lipid sphingosine-1-phosphate (S1P) to positively regulate anti-apoptotic/pro-survival responses by binding to S1P1 is well known, the molecular mechanisms remain unclear. Here we demonstrate that expression of S1P1 renders CCL39 lung fibroblasts resistant to apoptosis following growth factor withdrawal. Resistance to apoptosis was associated with attenuated accumulation of pro-apoptotic BH3-only protein Bim. However, although blockade of extracellular signal-regulated kinase (ERK) activation could reverse S1P1-mediated suppression of Bim accumulation, inhibition of caspase-3 cleavage was unaffected. Instead S1P1-mediated inhibition of caspase-3 cleavage was reversed by inhibition of phosphatidylinositol-3-kinase (PI3K) and protein kinase C (PKC), which had no effect on S1P1 regulation of Bim. However, S1P1 suppression of caspase-3 was associated with increased expression of anti-apoptotic protein Mcl-1, the expression of which was also reduced by inhibition of PI3K and PKC. A role for the induction of Mcl-1 in regulating endogenous S1P receptor-dependent pro-survival responses in human umbilical vein endothelial cells was confirmed using S1P receptor agonist FTY720-phosphate (FTY720P). FTY720P induced a transient accumulation of Mcl-1 that was associated with a delayed onset of caspase-3 cleavage following growth factor withdrawal, whereas Mcl-1 knockdown was sufficient to enhance caspase-3 cleavage even in the presence of FTY720P. Consistent with a pro-survival role of S1P1 in disease, analysis of tissue microarrays from ER+ breast cancer patients revealed a significant correlation between S1P1 expression and tumour cell survival. In these tumours, S1P1 expression and cancer cell survival were correlated with increased activation of ERK, but not the PI3K/PKB pathway. In summary, pro-survival/anti-apoptotic signalling from S1P1 is intimately linked to its ability to promote the accumulation of pro-survival protein Mcl-1 and downregulation of pro-apoptotic BH3-only protein Bim via distinct signalling pathways. However, the functional importance of each pathway is dependent on the specific cellular context

Non-Neuronal Functions of the M2 Muscarinic Acetylcholine Receptor

Acetylcholine is an important neurotransmitter whose effects are mediated by two classes of receptors. The nicotinic acetylcholine receptors are ion channels, whereas the muscarinic receptors belong to the large family of G protein coupled seven transmembrane helix receptors. Beyond its function in neuronal systems, it has become evident that acetylcholine also plays an important role in non-neuronal cells such as epithelial and immune cells. Furthermore, many cell types in the periphery are capable of synthesizing acetylcholine and express at least some of the receptors. In this review, we summarize the non-neuronal functions of the muscarinic acetylcholine receptors, especially those of the M2 muscarinic receptor in epithelial cells. We will review the mechanisms of signaling by the M2 receptor but also the cellular trafficking and ARF6 mediated endocytosis of this receptor, which play an important role in the regulation of signaling events. In addition, we provide an overview of the M2 receptor in human pathological conditions such as autoimmune diseases and cancer