Project Details
Projekt
Functional characterization of Laminin 10
Applicant
Professorin Dr. Lydia Sorokin
Subject Area
Dermatology
Term
from 2000 to 2003
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 5244254
We have identified and characterized the laminin isoforms expressed by endothelium; laminin 8 (alpha4 beta1 gamma1) is widely expressed in all endothelium regardless of the stage of development, while laminin 10 (alpha5 beta1 gamma1) is restricted to basement membranes (BM) of mature capillaries and some venules, appearing only 3 - 4 weeks after birth. Expression of laminin alpha4 and alpha5 chains is further regulated by the activation state of endothelial cells; cytokines which play a role in inflammatory events such as IL-1 and TNF-alpha upregulate laminin alpha4; while angiostatic agents such as progesterone and its derivatives upregulated laminin alpha5. Why different vessels express different laminins and why they are differentially regulated in these cells is unknown, but suggests functional distinction. The laminin alpha5 chain has recently been eliminated in mice, however, the animals die too early in embryogenesis to permit identifications of sites of functional significance. It is proposed, therefore, to use the Cre-loxP recombinase system, with Cre-expression under the control of an endothelial cell specific promoter (Tie-1), to eliminate laminin alpha5 expression specifically from endothelial cell BM to assess its function at this site. Further, laminin alpha5 expression will be ablated in a time-dependent manner using Cre-loxP recombinase, with Cre under the control of an inducible promoter (the modified oestrogen receptor - tamoxifen system). Laminin alpha5 expression will be eliminated 3 - 4 weeks after birth when it first appears in endothelial BM. In situ hybridization studies carried out in our laboratory have shown that laminin alpha5 mRNA expression at sites other than endothelium is minimal after birth, with the exception of epithelia (28,30). This system therefore privides not only the opportunity of examining the function of laminin alpha5 in endothelium, but also in mature epithelium.
DFG Programme
Priority Programmes
