The role of NUMB, a protein important for cellular differentiation and endocytosis in non-placental cells, was investigated in syncytiotrophoblast development and function in the human placenta. The BeWo choriocarcinoma cell line was used as a model for villous cytotrophoblast cells and syncytiotrophoblast to investigate NUMB’s involvement in differentiation and epidermal growth factor receptor (EGFR) endocytosis. NUMB isoforms 1 and 3 were found to be the predominant isoforms and were upregulated following forskolin-induced differentiation. Overexpression of NUMB isoforms 1 and 3 did not mediate differentiation or EGFR signaling. Immunofluorescence analysis revealed that NUMB colocalized with EGFR at perinuclear late endosomes and lysosomes following EGF stimulation. We have demonstrated for the first time that NUMB isoforms 1 and 3 are expressed in BeWo cells, are upregulated in forskolin-differentiated BeWo cells and are involved in ligand-dependent EGFR endocytosis in BeWo cells.

Diss. (sammanfattning) Uppsala : Univ., 2003. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2006. / Härtill 5 uppsatser.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Chicago, Dept. of Molecular Genetics and Cell Biology, March 2000. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph.D.) - University of Queensland, 2002. / Includes bibliography.

No description available.

No description available.

Cellular pH homeostasis plays crucial roles in cellular functions, and it is now widely recognized that Na⁺/H⁺ exchangers are among the most prominent players in this process. Although recently described mammalian Na⁺/H⁺ exchanger NHE7 has attracted much attention, its biological functions remain largely unknown. Most proteins exist as protein complexes in the cell and elicit their unique functions in collaboration with their binding partners. Therefore, identification and characterization of binding proteins will often unveil unexpected functions of the protein of interest. To begin to elucidate biological roles of the novel class of Na⁺/H⁺ exchanger NHE7, yeast two-hybrid screening was conducted and several binding candidates were identified. Among these candidates, I show that Secretory Carrier Membrane Proteins (SCAMPs) are novel NHE7 binding proteins and that SCAMPs regulate endocytic trafficking of NHE7 from the recycling endosomes to the trans-Golgi network (TGN). In agreement with this finding, I found that NHE7 can also be targeted to the plasma membrane and then internalized. Caveolins, structural proteins for caveolae, were identified as NHE7-binding proteins and it was initially hypothesized that caveolins might regulate NHE7-internalization. Interestingly, caveolins bound to NHE7 through a novel binding domain and facilitated its association to caveolae/lipid rafts, but did not affect NHE7-internalization. I also show that SCAMP2 associates with the heterotrimeric G protein β subunit (Gβ) and regulates the ERK1/2 signaling. Moreover, NHE7 was found to associate with both SCAMP2 and Gβ in the cell, suggesting that ERK1/2 signaling mediated by the SCAMP2-Gβ complex might regulate NHE7. / Medicine, Faculty of / Biochemistry and Molecular Biology, Department of / Graduate

The role of NUMB, a protein important for cellular differentiation and endocytosis in non-placental cells, was investigated in syncytiotrophoblast development and function in the human placenta. The BeWo choriocarcinoma cell line was used as a model for villous cytotrophoblast cells and syncytiotrophoblast to investigate NUMB’s involvement in differentiation and epidermal growth factor receptor (EGFR) endocytosis. NUMB isoforms 1 and 3 were found to be the predominant isoforms and were upregulated following forskolin-induced differentiation. Overexpression of NUMB isoforms 1 and 3 did not mediate differentiation or EGFR signaling. Immunofluorescence analysis revealed that NUMB colocalized with EGFR at perinuclear late endosomes and lysosomes following EGF stimulation. We have demonstrated for the first time that NUMB isoforms 1 and 3 are expressed in BeWo cells, are upregulated in forskolin-differentiated BeWo cells and are involved in ligand-dependent EGFR endocytosis in BeWo cells.