Genetic mutations cause primary immunodeficiencies (PIDs), which predispose to infections. Here we describe Activated PI3K-δ Syndrome (APDS), a PID associated with a dominant gain-offunction mutation E1021K in the p110δ protein, the catalytic subunit of phosphoinositide 3-kinase δ (PI3Kδ), encoded by the PIK3CD gene. We found E1021K in 17 patients from seven unrelated

Dopamine and endogenous cannabinoids display complex interactions in the basal ganglia. One possible level of interaction is between CB1 cannabinoid and D2 dopamine receptors. Here, we demonstrate that a regulated association of CB1 and D2 receptors profoundly alters CB1 signaling. This provides the first evidence that CB1/D2 receptor complexes exist, are dynamic, and are agonist-regulated with highest complex levels detected when both receptors are stimulated with subsaturating concentrations of agonist. The consequence of this interaction is a differential preference for signaling through a "nonpreferred" G protein. In this case, D2 receptor activation, simultaneously with CB1 receptor stimulation, results in the receptor complex coupling to G␣s protein in preference to the expected G␣i/o proteins. The result of this interaction is an increase in the second messenger cAMP, reversing an initial synergistic inhibition of adenylyl cyclase activity seen at subthreshold concentrations of cannabinoid agonist. Additionally, a pertussis toxin insensitive component in the activation of extracellular signal-regulated kinase (ERK) 1/2 kinases by the cannabinoid agonist CP 55,940 [(1R,3R,4R)-3-[2-hydroxy-4-(1,1-dimethylheptyl)phenyl]-4-(3-hydroxypropyl)cyclohexan-1-ol] is revealed in cells stably expressing both CB1 and D2 receptors. Thus, concurrent receptor stimulation promotes a heterooligomeric receptor complex and an apparent shift of CB1 signaling from a pertussis toxin-sensitive inhibition to a partly pertussis toxin-insensitive stimulation of adenylyl cyclase and ERK 1/2 phosphorylation.

The vacuolar-type ATPase (H+ATPase) is a ubiquitously expressed multisubunit pump whose regulation is poorly understood. Its membrane-integral a-subunit is involved in proton translocation and in humans has four forms, a1–a4. This study investigated two naturally occurring point mutations in a4's COOH terminus that cause recessive distal renal tubular acidosis (dRTA), R807Q and G820R. Both lie within a domain that binds the glycolytic enzyme phosphofructokinase-1 (PFK-1). We recreated these disease mutations in yeast to investigate effects on protein expression, H+ATPase assembly, targeting and activity, and performed in vitro PFK-1 binding and activity studies of mammalian proteins. Mammalian studies revealed complete loss of binding between the COOH terminus of a4 containing the G-to-R mutant and PFK-1, without affecting PFK-1's catalytic activity. In yeast expression studies, protein levels, H+ATPase assembly, and targeting of this mutant were all preserved. However, severe (78%) loss of proton transport but less decrease in ATPase activity (36%) were observed in mutant vacuoles, suggesting a requirement for the a-subunit/PFK-1 binding to couple these two functions. This role for PFK in H+ATPase function was supported by similar functional losses and uncoupling ratio between the two proton pump domains observed in vacuoles from a PFK-null strain, which was also unable to grow at alkaline pH. In contrast, the R-to-Q mutation dramatically reduced a-subunit production, abolishing H+ATPase function completely. Thus in the context of dRTA, stability and function of the metabolon composed of H+ATPase and glycolytic components can be compromised by either loss of required PFK-1 binding (G820R) or loss of pump protein (R807Q).

1 We investigated the ability of the activated m-opioid receptor (MOR) to differentiate between myristoylated G ai1 and G aoA type G a proteins, and the maximal activity of a range of synthetic and endogenous agonists to activate each G a protein.2 Membranes from HEK293 cells stably expressing transfected MOR were chaotrope extracted to denature endogenous G-proteins and reconstituted with specific purified G-proteins. The G a subunits were generated in bacteria and were demonstrated to be recognised equivalently to bovine brain purified G a protein by CB 1 cannabinoid receptors. The ability of agonists to catalyse the MORdependent GDP/[35 S]GTP g S exchange was then compared for G ai1 and G aoA . 3 Activation of MOR by DAMGO produced a high-affinity saturable interaction for G aoA (K m ¼ 2071 nM) but a low-affinity interaction with G ai1 (K m ¼ 116712 nM). DAMGO, metenkephalin and leucine-enkephalin displayed maximal G a activation among the agonists evaluated. Endomorphins 1 and 2, methadone and b-endorphin activated both G a to more than 75% of the maximal response, whereas fentanyl partially activated both G-proteins. 4 Buprenorphine and morphine demonstrated a statistically significant difference between the maximal activities between G ai1 and G aoA . Interestingly, DAMGO, morphine, endomorphins 1 and 2, displayed significant differences in the potencies for the activation of the two G a . Differences in maximal activity and potency, for G ai1 versus G aoA , are both indicative of agonist selective activation of G-proteins in response to MOR activation. 5 These findings may provide a starting point for the design of drugs that demonstrate greater selectivity between these two G-proteins and therefore produce a more limited range of effects.

In recent years, it has been demonstrated that high circulating levels of the endogenous cannabinoid anandamide, resulting from low expression of its metabolizing enzyme fatty acid amide hydrolase (FAAH), may contribute to spontaneous miscarriage and poor outcome in women undergoing in vitro fertilization. The site of action of this compound, however, has not been determined. In this study, we examined the distribution of the cannabinoid receptors, CB1 and CB2, and the endocannabinoid-metabolizing enzyme FAAH in first trimester human placenta. Here, we show that FAAH is expressed throughout the human first trimester placenta, in extravillous trophoblast columns, villous cytotrophoblasts, syncytiotrophoblasts, and macrophages. Furthermore, FAAH mRNA levels appear to be regulated during gestation, with levels peaking at 11 wk before declining again. The immune system-associated cannabinoid CB2 receptors were localized only to placental macrophages. Interestingly, the cannabinoid receptor CB1 was not identified in first trimester placenta despite having previously been shown to be present in placental tissues at term. These findings suggest that the placenta may form a barrier preventing maternal-fetal transfer of anandamide and/or modulate local levels of anandamide by regulation of FAAH expression with gestation.