Autophagy status in factor VIII secreting endothelial cells

M. A. Jamil, H. Singer, N. Nüsgen, J. Oldenburg, O. El-Maarri (Bonn, Germany)

Vascular wall biology and disorders
Date: 17.02.2017,
Time: 17:15 - 18:15

Objective: Liver sinusoidal endothelial cells (HHSEC) are considered as major source of F8. It is known that upon synthesis F8 is translocated into endoplasmic reticulum (ER) for cleavage, folding and quality assessment. These processes require constant ER turnover and modulation, in which autophagy plays an important role. ER expansion, ER fragmentation or lysosome degradation may occur because of change in autophagy status. Also Takehiro, et al., states that inhibition or knockdown of autophagy essential genes decrease vWF secretion in endothelial cells; therefore it may be possible to have association between autophagy status and F8 secretion levels in different endothelial cells.

Methods: Behrends et. al (2010) proposed a network of six ATG8 orthologues in human interacting with a cohort of 67 proteins, which are playing a significant role in autophagy. To study the status of autophagy in FVIII secreting endothelial cells, we created a network of the 67 proteins interacting with autophagy by using IPA knowledge base. 35 out of 67 proteins were directly interacting with autophagy and some through other proteins from the above mentioned 67 proteins. Thirty out of 35 interacting proteins have direct correlation with autophagy status (activation or inhibition), out of which 28 were positively correlated (activation) to autophagy status and only 2 (inhibiting) were negatively correlated to autophagy status. We predicted the autophagy status based on above network in 5 endothelial cells; HHSEC (adult and fetal), human cardiac microvascular endothelial cells (HCMEC), human pulmonary microvascular endothelial cells (HPMEC), human pulmonary artery endothelial cells (HPAEC) and human umbilical vein endothelial cells (HUVEC).

Results: We calculated the log fold changes of all endothelial cells to each other to rank them based on their autophagy status. Therefore, the endothelial cells could be ranked from highest activated to lowest: HHSEC adult-HUVEC-HPAEC-HPMEC-HCMEC-HHSEC fetal.

Conclusion: Our data suggest that higher autophagy-activation status is associated with higher rate of F8 secretion, however the intracellular molecular mechanisms that explains this phenomenon is/are still to be clarified.