These kinases are highly Palo Alto, California 94304 related in sequence, are rapidly activated following treatment with TNF or IL-1, and specifically phosphorylate the two critical serines of IB. In addition, catalyti-Summary cally inactive forms of IKK-␣ and IKK-␤ inhibit NF-B activation mediated by TNF and IL-1, suggesting that IB kinase-␣ and -␤ (IKK-␣ and IKK-␤), the catalytic IKK-␣ and -␤ are responsible for IB phosphorylation subunits of the IKK complex, phosphorylate IB proand subsequent NF-B activation. Recently, a third teins on specific serine residues, thus targeting IB component of the IKK complex, designated NEMO/ for degradation and activating the transcription factor IKK-␥, was identified by complementation cloning in NF-NF-B. To elucidate the in vivo function of IKK-␤, we B-unresponsive cells (Yamaoka et al., 1998) and by generated IKK-␤-deficient mice. The homozygous affinity purification using antibodies to IKK-␣ (Rothwarf mouse embryo dies at ‫5.41ف‬ days of gestation due et al., 1998). NEMO is a 47 kDa protein that interacts to liver degeneration and apoptosis. IKK-␤-deficient with IKK-␣ and IKK-␤. NEMO-deficient cells are unable embryonic fibroblasts have both reduced basal NF-B to activate NF-B in response to TNF, IL-1, or LPS. activity and impaired cytokine-induced NF-B activa-Furthermore, IKK complexes lacking NEMO cannot be tion. Similarly, basal and cytokine-inducible kinase acactivated to phosphorylate IB, indicating that NEMO tivities of the IKK complex are greatly reduced in IKKis an essential component of the IKK complex. ␤-deficient cells. These results indicate that IKK-␤ is NF-B-inducing kinase (NIK) and MEKK1 have been crucial for liver development and regulation of NF-B proposed to be upstream activators of IKKs (Malinin et activity and that IKK-␣ can only partially compensate al., 1997; Nemoto et al., 1998). NIK is a MEKK family for the loss of IKK-␤. member that binds to and activates both IKK-␣ and IKK-␤ when overexpressed (Regnier et al., 1997; Woronicz et al., 1997). In addition, NIK can phosphorylate

Lymphocytes home to lymph nodes, using L-selectin to bind specific ligands on high endothelial venules (HEV). In vitro studies implicate GlcNAc-6-sulfate as an essential posttranslational modification for ligand activity. Here, we show that genetic deletion of HEC-GlcNAc6ST, a sulfotransferase that is highly restricted to HEV, results in the loss of the binding of recombinant L-selectin to the luminal aspect of HEV, elimination of lymphocyte binding in vitro, and markedly reduced in vivo homing. Reactivity with MECA 79, an adhesion-blocking mAb that stains HEV in lymph nodes and vessels in chronic inflammatory sites, is also lost from the luminal aspects of HEV. These results establish a critical role for HEC-GlcNAc6ST in lymphocyte trafficking and suggest it as an important therapeutic target.

No abstract

Macrophage-mediated inflammation is central to atherogenesis. We have determined previously that the CXC chemokine receptor CXCR2 is involved in advanced atherosclerosis. We sought to determine whether one of the ligands of CXCR2, KC/GRO-␣, can also modulate atherogenesis. KC/GRO-␣ ؊/؊ mice were generated and mated with the atherosclerosis-prone LDLR ؊/؊ mice. There was a significant reduction in atherosclerosis in mice lacking KC/GRO-␣; however, this reduction was only approximately half that seen previously in mice lacking CXCR2 in the leukocyte. To determine whether CXCR2 is involved in the early formation of atherosclerosis, leukocyte-specific CXCR2 ؊/؊ chimeric mice on LDLR ؊/؊ background were generated. Early fatty streak lesion formation in these mice was not affected by leukocyte CXCR2 deficiency whereas lesions were less developed in mice lacking leukocyte CXCR2 when atherosclerosis was allowed to progress to the intermediate stage.

Complex airway diseases such as asthma and chronic obstructive pulmonary disease exhibit stereotyped traits (especially airway hyperreactivity and mucous cell metaplasia) that are variably expressed in each patient. Here, we used a mouse model for virus-induced long-term expression of these traits to determine whether individual traits can be genetically segregated and thereby linked to separate determinants. We showed that an F2 intercross population derived from susceptible and nonsusceptible mouse strains can manifest individual phenotypic extremes that exhibit one or the other disease trait. Functional genomic analysis of these extremes further indicated that a member of the calcium-activated chloride channel (CLCA) gene family designated mClca3 was inducible with mucous cell metaplasia but not airway hyperreactivity. In confirmation of this finding, we found that mClca3 gene transfer to mouse airway epithelium was sufficient to induce mucous cell metaplasia but not airway hyperreactivity. However, newly developed mClca3(-/-) mice exhibited the same degree of mucous cell metaplasia and airway hyperreactivity as wild-type mice. Bioinformatic analysis of the Clca locus led to the identification of mClca5, and gene transfer indicated that mClca5 also selectively drives mucous cell metaplasia. Thus, in addition to the capacity of CLCA family members to exhibit diverse functional activities, there is also preserved function so that more than one family member mediates mucous cell metaplasia. Nonetheless, Clca expression appears to be a selective determinant of mucous cell metaplasia so that shared homologies between CLCA family members may still represent a useful target for focused therapeutic intervention in hypersecretory airway disease.