Synopsis Previous studies showed that apolipoprotein E (apoE) expression in macrophages suppresses inflammatory response. Whether the endogenously synthesized apoE acts intracellularly or after its secretion in suppressing macrophage inflammation remains unclear. The current study used the murine macrophage cell line RAW 264.7 to examine the influence of exogenous apoE on macrophage inflammatory responses induced by toll-like receptor (TLR)-4 and TLR-3 agonists lipopolysaccharide (LPS) and poly(I-C), respectively. Results showed that exogenously added apoE suppressed LPS- and poly(I-C)-induction of interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF)-α secretion by RAW 264.7 cells. The mechanism was related to apoE suppression of TLR agonist-induced phosphorylation of c-Jun N-terminal kinase (JNK) and c-Jun. A peptide containing tandem repeat sequence of the receptor binding domain of apoE, apoE(141–155)2, was similarly effective in inhibiting LPS- and poly(I-C)-induced macrophage inflammatory response. Reductive methylation of lysine residues in apoE, which abolished its receptor binding capability without affecting its ability to interact with heparin-sulfate proteoglycans (HSPG), inhibited the ability of apoE to suppress macrophage response to LPS but had no effect on apoE suppression of poly(I-C)-induced macrophage activation. The ability of apoE to suppress poly(I-C)-induced pro-inflammatory cytokine production was abolished by heparinase treatment of RAW 264.7 cells to remove cell surface HSPG. Taken together, these results indicate that exogenous apoE inhibits macrophage inflammatory response to TLR4- and TLR-3 agonists through distinct mechanisms related to receptor and HSPG binding, respectively, and that these inhibitory effects converged on suppression of JNK and c-Jun activation that are necessary for macrophage activation.

Carboxyl ester lipase (CEL, also called cholesterol esterase or bile salt-dependent lipase) is a lipolytic enzyme capable of hydrolyzing cholesteryl esters, triacylglycerols, and phospholipids in a trihydroxy bile salt-dependent manner but hydrolyzes ceramides and lysophospholipids via bile salt-independent mechanisms. Although CEL is synthesized predominantly in the pancreas, a low level of CEL expression was reported in human macrophages. This study used transgenic mice with macrophage CEL expression at levels comparable with that observed in human macrophages to explore the functional role and physiological significance of macrophage CEL expression. Peritoneal macrophages from CEL transgenic mice displayed a 4-fold increase in

Darier disease (DD) (MIM 124200) is an autosomal dominant skin disorder characterized by loss of adhesion between epidermal cells and by abnormal keratinization. We present linkage analysis showing, in four families, key recombination events that refine the location of the DD locus on chromosome 12q23-24.1 to a region of <1 cM. We have constructed a YAC/P1 artificial chromosome (PAC)/bacterial artificial chromosome (BAC)-based physical map that encompasses this refined DD region. The map consists of 35 YAC, 69 PAC, 16 BAC, and 2 cosmid clones that were ordered by mapping 54 anonymous sequence-tagged sites. The critical region is estimated to be 2.4 Mb in size, with an average marker resolution of 37.5 kb. The refinement of the critical interval excludes the ALDH2, RPL6, PTPN11, and OAS genes, as well as seven expressed sequence tags (ESTs) previously mapped in the DD region. The three known genes (ATP2A2, PPP1CC, and SCA2) and the 10 ESTs mapped within the critical region are not obvious candidates for the DD gene. Therefore, this detailed integrated physical, genetic, and partial transcript map provides an important resource for the isolation of the DD gene and, possibly, other disease genes.