Previous work has led us to propose that close cell-cell associations during D. discoideum develo... more Previous work has led us to propose that close cell-cell associations during D. discoideum development serve as a signal to deactivate expression of discoidin I mRNA, and that intracellular cAMP serves as a mediator of this regulatory pathway. This model is based in part on the failure of a morphogenetic mutant, EB-21, to deactivate discoidin I expression under conditions where these cells fail to acquire cell-cell cohesiveness and hence remain as single cells, unlike the wild type strain which forms multicellular aggregates. Here we show that the failure of EB-21 to express specific cohesiveness depends on developmental conditions, and that under conditions where close cell-cell associations are allowed to form, discoidin I mRNA expression is deactivated normally. Furthermore, in both wild type and EB-21 there is a close correlation between formation close cell-cell associations and elevation of intracellular cAMP under different developmental conditions. Additional analyses of the biological behavior of EB-21 indicate that it acquires a normal cAMP chemotactic signal-response system, and that the morphogenetic defect cannot be corrected by co-development with wild type cells. The results are discussed in terms of possible relationships between cell-cell interactions, cAMP metabolism, and developmental gene expression in this organism.
We analyzed the roles of the individual measles virus (MV) surface glycoproteins in mediating fun... more We analyzed the roles of the individual measles virus (MV) surface glycoproteins in mediating functional and structural interactions with human CD46, the primary MV receptor. On one cell population, recombinant vaccinia virus vectors were used to produce the MV hemagglutinin (H) and fusion (F) glycoproteins. As fusion partner cells, various cell types were examined, without or with human CD46 (endogenous or recombinant vaccinia virus encoded). Fusion between the two cell populations was monitored by a quantitative reporter gene activation assay and by syncytium formation. MV glycoproteins promoted fusion with primate cells but not with nonprimate cells; recombinant CD46 rendered nonprimate cells competent for MV glycoprotein-mediated fusion. Markedly different fusion specificity was observed for another morbillivirus, canine distemper virus (CDV): recombinant CDV glycoproteins promoted fusion with primate and nonprimate cells independently of CD46. Fusion by the recombinant MV and C...
We analyzed the roles of the individual measles virus (MV) surface glycoproteins in mediating fun... more We analyzed the roles of the individual measles virus (MV) surface glycoproteins in mediating functional and structural interactions with human CD46, the primary MV receptor. On one cell population, recombinant vaccinia virus vectors were used to produce the MV hemagglutinin (H) and fusion (F) glycoproteins. As fusion partner cells, various cell types were examined, without or with human CD46 (endogenous or recombinant vaccinia virus encoded). Fusion between the two cell populations was monitored by a quantitative reporter gene activation assay and by syncytium formation. MV glycoproteins promoted fusion with primate cells but not with nonprimate cells; recombinant CD46 rendered nonprimate cells competent for MV glycoprotein-mediated fusion. Markedly different fusion specificity was observed for another morbillivirus, canine distemper virus (CDV): recombinant CDV glycoproteins promoted fusion with primate and nonprimate cells independently of CD46. Fusion by the recombinant MV and C...
Previous work has led us to propose that close cell-cell associations during D. discoideum develo... more Previous work has led us to propose that close cell-cell associations during D. discoideum development serve as a signal to deactivate expression of discoidin I mRNA, and that intracellular cAMP serves as a mediator of this regulatory pathway. This model is based in part on the failure of a morphogenetic mutant, EB-21, to deactivate discoidin I expression under conditions where these cells fail to acquire cell-cell cohesiveness and hence remain as single cells, unlike the wild type strain which forms multicellular aggregates. Here we show that the failure of EB-21 to express specific cohesiveness depends on developmental conditions, and that under conditions where close cell-cell associations are allowed to form, discoidin I mRNA expression is deactivated normally. Furthermore, in both wild type and EB-21 there is a close correlation between formation close cell-cell associations and elevation of intracellular cAMP under different developmental conditions. Additional analyses of the biological behavior of EB-21 indicate that it acquires a normal cAMP chemotactic signal-response system, and that the morphogenetic defect cannot be corrected by co-development with wild type cells. The results are discussed in terms of possible relationships between cell-cell interactions, cAMP metabolism, and developmental gene expression in this organism.
We analyzed the roles of the individual measles virus (MV) surface glycoproteins in mediating fun... more We analyzed the roles of the individual measles virus (MV) surface glycoproteins in mediating functional and structural interactions with human CD46, the primary MV receptor. On one cell population, recombinant vaccinia virus vectors were used to produce the MV hemagglutinin (H) and fusion (F) glycoproteins. As fusion partner cells, various cell types were examined, without or with human CD46 (endogenous or recombinant vaccinia virus encoded). Fusion between the two cell populations was monitored by a quantitative reporter gene activation assay and by syncytium formation. MV glycoproteins promoted fusion with primate cells but not with nonprimate cells; recombinant CD46 rendered nonprimate cells competent for MV glycoprotein-mediated fusion. Markedly different fusion specificity was observed for another morbillivirus, canine distemper virus (CDV): recombinant CDV glycoproteins promoted fusion with primate and nonprimate cells independently of CD46. Fusion by the recombinant MV and C...
We analyzed the roles of the individual measles virus (MV) surface glycoproteins in mediating fun... more We analyzed the roles of the individual measles virus (MV) surface glycoproteins in mediating functional and structural interactions with human CD46, the primary MV receptor. On one cell population, recombinant vaccinia virus vectors were used to produce the MV hemagglutinin (H) and fusion (F) glycoproteins. As fusion partner cells, various cell types were examined, without or with human CD46 (endogenous or recombinant vaccinia virus encoded). Fusion between the two cell populations was monitored by a quantitative reporter gene activation assay and by syncytium formation. MV glycoproteins promoted fusion with primate cells but not with nonprimate cells; recombinant CD46 rendered nonprimate cells competent for MV glycoprotein-mediated fusion. Markedly different fusion specificity was observed for another morbillivirus, canine distemper virus (CDV): recombinant CDV glycoproteins promoted fusion with primate and nonprimate cells independently of CD46. Fusion by the recombinant MV and C...
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Papers by Ed Rockville