Quantitative analysis on secretion level of CDNF regulated by two key α-helices in CDNF protein

Cerebral dopamine neurotrophic factor (CDNF) has been considered as potent candidates for the therapy of Parkinson's disease (PD) for which can promote the survival of midbrain dopaminergic neurons. In addition to secret out from cells like other classical neurotrophic factors (NTFs), CDNF can locate in the endoplasmatic reticulum (ER), where they can function as ER stress response protein to regulate ER stress. In our previous studies, we have found two helices, α1 and α7, which can regulate the intracellular trafficking and secretion of CDNF. α1 distruction can significantly retain CDNF protein in the ER, but α7 distruction induce most CDNF protein secreting out the cells. Then α1 and α7 regulate protein trafficking and secretion in opposite side. However, the exact secretion level of CDNF affected by α1 or α7 have not been sensitively quantified. In this study, we used nanoluciferase to quantify the secretion level of CDNF protein so that we could evaluate the impact of α1 and α7 on CDNF secretion or function.