The apical and basolateral plasma membrane domains of polarized epithelial cells contain distinct sets of integral membrane proteins. Biosynthetic targeting of proteins to the basolateral plasma membrane is mediated by cytosolic tail determinants, many of which resemble signals involved in the rapid endocytosis or lysosomal targeting. Since these signals are recognized by adaptor proteins, we hypothesized that there could be epithelial-specific adaptors involved in polarized sorting. Here, we report the identification of a novel member of the adaptor medium chain family, named W W1B, which is closely related to the previously described W W1A (79% amino acid sequence identity). Northern blotting and in situ hybridization analyses reveal the specific expression of W W1B mRNA in a subset of polarized epithelial and exocrine cells. Yeast two-hybrid analyses show that W W1B is capable of interacting with generic tyrosine-based sorting signals. These observations suggest that W W1B may be involved in protein sorting events specific to polarized cells.

The UNC-51 serine/threonine kinase of C. elegans plays an essential role in axonal elongation, and unc-51 mutants exhibit uncoordinated movements. We have previously identi®ed mouse and human cDNAs encoding UNC-51-like kinase (ULK1). Here we report the identi®cation and characterization of the second murine member of this kinase family, ULK2. Mouse ULK2 cDNA encodes a putative polypeptide of 1033 aa which has an overall 52% and 33% amino acid identity to ULK1 and UNC-51, respectively. ULKs and UNC-51 share a typical domain structure of an amino-terminal kinase domain, a central proline/serine rich (PS) domain, and a carboxy-terminal (C) domain. Northern blot analysis showed that ULK2 mRNA is widely expressed in adult tissues. In situ hybridization analysis indicated that ULK2 mRNA is ubiquitously localized in premature as well as mature neurons in developing nervous system. ULK2 gene was mapped to mouse chromosome 11B1.3 and rat chromosome 10q23 by FISH. HA-tagged ULK2 expressed in COS7 cells had an apparent molecular size of *150 kDa and was autophosphorylated in vitro. Truncation mutants suggested that the autophosphorylation occurs in the PS domain. Although expression of ULK2 failed to rescue unc-51 mutant of C. elegans, a series of ULK2/UNC-51 chimeric kinases revealed that function of the kinase and PS domains are conserved among species, while the C domain acts in a speciesspeci®c manner. These results suggest that ULK2 is involved in a previously uncharacterized signaling pathway in mammalian cells.

Vascularization defects in genetic recombinant mice have defined critical roles for a number of specific receptor tyrosine kinases. Here we evaluated whether an endothelium-expressed receptor tyrosine phosphatase, CD148 (DEP-1/PTP), participates in developmental vascularization. A mutant allele, CD148⌬CyGFP , was constructed to eliminate CD148 phosphatase activity by in-frame replacement of cytoplasmic sequences with enhanced green fluorescent protein sequences. Homozygous mutant mice died at midgestation, before embryonic day 11.5 (E11.5), with vascularization failure marked by growth retardation and disorganized vascular structures. Structural abnormalities were observed as early as E8.25 in the yolk sac, prior to the appearance of intraembryonic defects. Homozygous mutant mice displayed enlarged vessels comprised of endothelial cells expressing markers of early differentiation, including VEGFR2 (Flk1), Tal1/SCL, CD31, ephrin-B2, and Tie2, with notable lack of endoglin expression. Increased endothelial cell numbers and mitotic activity indices were demonstrated. At E9.5, homozygous mutant embryos showed homogeneously enlarged primitive vessels defective in vascular remodeling and branching, with impaired pericyte investment adjacent to endothelial structures, in similarity to endoglin-deficient embryos. Developing cardiac tissues showed expanded endocardial projections accompanied by defective endocardial cushion formation. These findings implicate a member of the receptor tyrosine phosphatase family, CD148, in developmental vascular organization and provide evidence that it regulates endothelial proliferation and endothelium-pericyte interactions.A number of cell surface receptors coupled with activating ligands play central roles in the coordination of embryonic vascular development and postnatal neovascularization (11,37). Prominent among these coordinators of development and neovascularization are vascular endothelial growth factor (VEGF) and its receptors VEGFR1 and -2 (Flt-1 and KDR/ Flk1); ephrin-B2 and its receptor EphB4; angiopoietins 1 and 2 and the Tie2 receptor; platelet-derived growth factor (PDGF)-B and PDGF␤ receptor; receptors for the transforming growth factor ␤ (TGF␤) superfamily (TGF␤ type ⌱⌱ receptor, activin-receptor-like kinase 1 [Alk1], and endoglin) (32, 34, 35); and Jagged1 and Notch1 and -4 (28, 51).Coordinated assembly of vascular elements requires regulated signaling to control at least three functional components of the process. These include (i) differentiation and expansion of endothelial progenitors, (ii) assembly and differential growth of interconnecting vascular networks, and (iii) progressive investment and maturation of vessels with supportive structures, including either pericytes (PCs) or vascular smooth muscle cells (vSMCs). The VEGFs and their receptors are required for endothelial differentiation and primary capillary plexus formation in vasculogenesis (18). Both the ephrin-B2 transmembrane counterreceptor and EphB4 receptor are essential for interconnection and matura...

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The gene for the beta-chain of the high-affinity receptor for IgE (Fc epsilon RI beta) has been proposed as a candidate gene for atopy. A coding variant Glu237Gly has been studied in various populations with asthma and atopy, and the results were controversial for association of the variant with atopy/asthma. Because nasal allergy is a more common atopic disease and shows less remission than asthma, we analyzed whether the Glu237Gly variant is correlated with nasal allergy. The study enrolled 233 patients with nasal allergy and 100 control subjects. Further, three subgroups were selected: patients with perennial nasal allergy (n=149), Japanese cedar pollinosis (n=189), and allergy to multiple allergens (n=45). The allele frequency of Gly237 in the controls and patients was 0.14 and 0.20, and the frequency of Gly237-positive subjects was 0.23 and 0.356, respectively. There was a significant association between Gly237-positivity and nasal allergy, perennial nasal allergy, Japanese cedar pollinosis, and allergy to multiple allergens. Among all 333 subjects we observed a significant relationship between Gly237 and elevated levels of serum total IgE (>250 IU/ml) and very high IgE (>1000 IU/ml). Among patients positive for a specific IgE, Gly237 was significantly associated with high IgE for house dust, mite, and Japanese cedar pollen. These results suggest that the Glu237Gly variant of the Fc epsilon RI beta gene is involved in the development of nasal allergy through the process for the production of both specific and nonspecific IgE antibodies.