Poster Presenter

Soluble Endoglin Could Excert A Modulatory Effect on the TGF-β1 Signaling Pathways
Mohammed S. Rizk, Steffen K. Meurer, Lidia Tihaa, Axel M.Gressner
Egypt

Introduction/Background: Importance of soluble endoglin (sCD105) concentration in the serum of patients with cirrhosis with and without hepatocellular carcinoma, in preeclampsia or in skin disease was studied but its biological functional relevance is still unclear.

Aim of the Work: Study the function of the soluble endoglin on TGF- β1 signalling in an established cellular assay, based on the TGF-β1 Smad3 dependent (CAGA)12-MLP Luc reporter in both primary hepatocytes and L6E9 myoblast cells of rat origin and purification of human serum endoglin.

Materials and Methods: Coding sequence for the extracellular domain was amplified by using the cDNA encoding the full length endoglin by RT-PCR keeping in mind the antibody epitopes and the domain structure of the full length receptor. The cloned ECD was ligated to expression vector pcDNA and expression for the ECD of endoglin was tested first. Primary rat hepatocytes and L6E9 myoblast cells was transfected by empty vector (as a negative control), by expression vector pcDNA ECD endoglin, expression vector pcDNA containing the full endoglin receptor, and all cells was transfected by (CAGA)12-MLP Luc reporter containing expression vector to show the signal effect for TGF-β1 on cells.

Results: Heterologously expressed rat (sCD105) in primary rat hepatocytes and L6 E9 rat skeletal muscle cells, obviously showed an inhibition for TGF-β1/Smad3 signaling, measured by the CAGA-luciferase reporter, in primary hepatocytes. In contrast, (sCD105) had a stimulatory effect on TGF-β1/Smad3 signaling in L6 E9 cells. From these findings we conclude that the presence of soluble endoglin in the circulation might not a passive shedding, but could modulate signaling of TGF-β1 by the general tendency of the sCD105 for protein interactions in the serum as was pointed out in our FPLC analysis, in which the sCD105 eluted at a much higher molecular weight (~400 kDa).

Conclusion: sCD105 might have a potential role in treatment and management of disease will be evaluated in prospective studies.