Background and AimAssessment of serum concentration of lipopolysaccharide (LPS)-binding protein (LBP) has been suggested as a useful biomarker to indicate activation of innate immune responses to microbial products. We investigated LBP concentrations and associations with demographics, lifestyle factors, and common metabolic abnormalities in adults. We also examined if LBP concentrations were associated with common polymorphisms in genes coding for LBP (rs2232618), CD14 (rs2569190), and TLR4 (rs4986790), the molecules responsible for the innate immune response to LPS, or serum levels of soluble CD14 (sCD14) and proinflammatory cytokines.MethodsSerum LBP was measured with a commercial immunoassay in a random sample of the adult population (n = 420, 45% males, age 18–92 years) from a single municipality.ResultsSerum LBP concentrations increased with age (P<0.001) and were higher in individuals who were overweight or obese than in normal-weight individuals (P<0.001). Similarly, LBP concentrations were higher in individuals with metabolic syndrome than in individuals without it (P<0.001). Among metabolic syndrome components, LBP concentrations were independently associated with abdominal obesity (P = 0.002) and low concentrations of HDL-cholesterol (P<0.001). Serum LBP concentrations tended to be independently associated with smoking (P = 0.05), but not with alcohol consumption. Likewise, there was not significant association between LBP concentrations and gene polymorphisms. Concentrations of LBP significantly correlated with serum levels of proinflammatory cytokines (IL-6 and IL-8), sCD14, and with liver enzymes.ConclusionsSerum LBP concentrations increased with age. Overweight, obesity, and having metabolic syndrome (particularly, low HDL cholesterol levels) were associated with higher LBP concentrations. These findings are consistent with microbial exposure playing a role in these inflammatory, metabolic abnormalities.

The expression of the steroidogenic acute regulatory protein (STAR) is regulated by PKA in response to trophic hormone stimulation through the second messenger cAMP. However, in steroidogenic cells, the concentrations of hormone necessary to maximally induce cAMP synthesis and PKA activity are often significantly higher than is necessary to achieve maximum steroidogenesis. One general mechanism believed to make PKA signaling more effective is the use of A-kinase anchoring proteins (AKAPs) to recruit PKA to discrete subcellular compartments, which coordinates and focuses PKA action with respect to its substrates. The characterization of AKAP121 has suggested that it enhances the posttranscriptional regulation of STAR by recruiting both Star mRNA and PKA to the mitochondria, thereby permitting more effective translation and phosphorylation of STAR. Testing this hypothesis revealed that cAMP-induced STAR expression and steroidogenesis closely followed AKAP121 abundance when this AKAP was silenced or overexpressed in MA-10 cells but that these changes were effected posttranscriptionally. Moreover, silencing AKAP121 expression in these cells specifically altered the localization of type II PKA regulatory subunit alpha (PKAR2A) at the mitochondria but did not affect its relative expression within the cell. Affinity purification experiments showed that PKAR2A preferentially associated with AKAP121, and cAMP analogs that activate type II PKA induced STAR phosphorylation more efficiently than analogs stimulating type I PKA. This suggests that AKAP121 and PKAR2A serve to enhance steroidogenesis by directing the synthesis and activation of STAR at the mitochondria in response to cAMP.

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The anionic phosphide-bridged complexes (H-DBU)[M(2)Cp(2)(μ-PHR*)(CO)(4)] (M = Mo, W; R* = 2,4,6-C(6)H(2)(t)Bu(3); Cp = η(5)-C(5)H(5), DBU = 1,8-diazabicyclo [5.4.0] undec-7-ene) react with molecular oxygen to give the corresponding oxophosphinidene complexes (H-DBU)[MCp{P(O)R*}(CO)(2)] as major products (Mo-P = 2.239(1) Å for the Mo complex). The latter anionic complexes are protonated by HBF(4)·OEt(2) to give the hydroxyphosphide derivatives [MCp{P(OH)R*}(CO)(2)]. In the presence of excess acid, the molybdenum complex yields the fluorophosphide complex [MoCp(PFR*)(CO)(2)] (Mo-P = 2.204(1) Å), while the tungsten compound reacts with excess HCl to give an unstable chlorophosphine complex [WCpCl(PHClR*)(CO)(2)] which is rapidly hydrolyzed to give [WCpCl{PH(OH)R*}(CO)(2)], having a complexed arylphosphinous acid (Mo-P = 2.460(2) Å). The molybdenum anion reacts with strong C-based electrophiles such as [Me(3)O]BF(4), Et(2)SO(4), C(2)H(3)C(O)Cl, and PhC(O)Cl to give the corresponding alkoxyphosphide derivatives [MoCp{P(OR)R*}(CO)(2)] (R = Me, Et, COC(2)H(3), COPh; Mo-P = 2.197(2) Å for the benzoyl compound), as a result of the attack of the electrophile at the O atom of the oxophosphinidene ligand. In contrast, the reactions with milder alkylating reagents such as the alkyl halides MeI, EtI, C(3)H(5)Br, and C(3)H(3)Br give selectively the corresponding κ(2)-phosphinite complexes [MoCp{κ(2)-OP(R)R*}(CO)(2)] [R = Me, Et, C(3)H(5), C(3)H(3); Mo-P = 2.3733(5) Å for the allyl compound] as a result of the attack of the electrophile at the P atom of the oxophosphinidene ligand. According to density functional theory (DFT) calculations, the oxygen atom of the phosphinidene ligand bears the highest negative charge in the molybdenum anion, while the highest occupied molecular orbital (HOMO) of this complex has substantial Mo-P π bonding character. Thus, it is concluded that the phosphinite complexes are formed under conditions of orbital control, while charge-controlled reactions tend to give alkoxyphosphide derivatives.

The (H-DBU)+ salt of the anionic phosphinidene oxide complex [MoCp(CO)2{P(O)R*}]- (1) (DBU = 1,8-diazabicyclo[5.4.0]undec-7-ene; R* = 2,4,6-C6H2tBu3) reacts with different oxidizing agents, displaying a multisite activity located at the Mo and P atoms or at the Mo=P bond. Thus, reaction of 1 with [FeCp2]BF4 gives the dimer [Mo2Cp2(CO)4{P(O)R*}2], and reaction with bromine gives the phosphinous acid complex [MoBrCp{P(OH)(CH2CMe2C6H2tBu2}(CO)2], the latter arising from an unprecedented C-H bond addition to the oxide P=O moiety. In contrast, reaction of 1 with p-benzoquinone occurs at the P site to give the P,O-bound phosphonite complex [MoCp{kappa2-OP(OC6H4OH)R*}(CO)2]. Finally, oxygen or sulfur atoms are added to the Mo=P bond by reaction of 1 with Me2CO2 and S8 to give the novel dioxophosphorane or thiooxophosphorane complexes [MoCp(CO)2{kappa2-EP(O)R*}]- (E = O, S). The thiooxophosphorane anion is a good nucleophile and is methylated at either the S or O positions depending on the electrophile used (MeI or (Me3O)BF4) to give the isomers [MoCp{kappa2-(MeS)P(O)R*}(CO)2] and [MoCp{kappa2-SP(OMe)R*}(CO)2], both having novel organophosphorus ligands.

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Mice deficient in thyroid hormone receptor α (TRα) display hypersensitivity to thyroid hormone (TH), with normal serum TSH but diminished serum T(4). Our aim was to determine whether altered TH metabolism played a role in this hypersensitivity. TRα knockout (KO) mice have lower levels of rT(3), and lower rT(3)/T(4) ratios compared with wild-type (WT) mice. These alterations could be due to increased type 1 deiodinase (D1) or decreased type 3 deiodinase (D3). No differences in D1 mRNA expression and enzymatic activity were found between WT and TRαKO mice. We observed that T(3) treatment increased D3 mRNA in mouse embryonic fibroblasts obtained from WT or TRβKO mice, but not in those from TRαKO mice. T(3) stimulated the promoter activity of 1.5 kb 5'-flanking region of the human (h) DIO3 promoter in GH3 cells after cotransfection with hTRα but not with hTRβ. Moreover, treatment of GH3 cells with T(3) increased D3 mRNA after overexpression of TRα. The region necessary for the T(3)-TRα stimulation of the hD3 promoter (region -1200 to -1369) was identified by transfection studies in Neuro2A cells that stably overexpress either TRα or TRβ. These results indicate that TRα mediates the up-regulation of D3 by TH in vitro. TRαKO mice display impairment in the regulation of D3 by TH in both brain and pituitary and have reduced clearance rate of TH as a consequence of D3 deregulation. We conclude that the absence of TRα results in decreased clearance of TH by D3 and contributes to the TH hypersensitivity.

Reaction of [Mo2Cp2(mu-H)(mu-PHR*)(CO)4] with DBU followed by O2 gives the first anionic phosphinidene oxide complex (H-DBU)[MoCp{P(O)R*}(CO)2] (1) (DBU = 1,8-diazabicyclo [5.4.0] undec-7-ene; R* = 2,4,6-C6H2tBu3). This anion displays three different nucleophilic sites located at the O, P, and Mo atoms, as illustrated by the reactions reported. Thus, reaction of 1 with excess HBF4.OEt2 gave the fluorophosphide complex [MoCp(PFR*)(CO)2] via the hidroxophosphide intermediate [MoCp{PR*(OH)}(CO)2]. Related alkoxyphosphide compounds [MoCp{P(OR)R*}(CO)2] (R = Me, C(O)Ph) were prepared by reaction of 1 with [Me3O]BF4 and PhC(O)Cl, respectively, whereas reaction of 1 with MeI or C3H5Br gave the P,O-bound phosphinite complexes [MoCp(kappa2-OPRR*)(CO)2] (R = Me, C3H5). Metal-based electrophiles were found to bind at either O or Mo positions. Thus, reaction of 1 with [ZrCl2Cp2] gave the phosphinidene oxide bridged [MoCp{P(OZrClCp2)R*}(CO)2], whereas reaction with SnPh3Cl gave trans-[MoCp{P(O)R*}(CO)2(SnPh3)], an heterometallic complex having an intact terminal P(O)R* ligand.