Cooperative regulation of neuronal autophagy by Sigma-1-Receptor and Wolfram syndrome-causing Wolframin

Wolfram综合征（WS）是一种罕见的神经退行性疾病，由Wolfram -1 （WFS1）基因突变引起，并伴有视神经萎缩、耳聋和糖尿病。WS没有治疗方法，患者在35岁左右死于呼吸或吞咽衰竭。最近，我们证明了内质网（ER）和线粒体之间通过所谓的MAM位点（线粒体相关膜）紧密连接的通信在WS中受损，导致线粒体缺陷。我们的数据确实表明，通过靶向er线粒体功能来恢复异常是可能的。sigma-1受体（S1R）是一种在MAMs中高度富集的跨膜蛋白。它与参与内质网线粒体Ca2+转移的几个伙伴相互作用，从而增强Ca2+从内质网外排到线粒体并改善线粒体功能。我们使用S1R激动剂PRE-084来证明MAM功能增强可以用于恢复WS的改变。PRE-084治疗在体外恢复Ca2+转移和线粒体呼吸，纠正相关的自噬和线粒体自噬受损，并能够减轻在两种遗传动物模型中观察到的行为症状。这种意想不到的自噬/有丝分裂的改变促使我们确定了WFS1的结合伴侣。我们分离了几个参与自噬过程调节的伙伴。该项目的目的是破译WFS1和S1R调节神经元自噬的分子机制。利用缺乏WFS1和S1R的细胞和体内模型，我们将确认WFS1与其猎物的相互作用，并评估WFS1和S1R功能丧失对猎物效应的影响。此外，我们将确定蛋白质在神经元自噬体形成和运输中的作用。最后，我们将在神经元的不同位置用光开关激动剂激活S1R，以确定其确切的作用机制。

Wolfram syndrome (WS) is a rare neurodegenerative disease caused by mutations in the gene for wolframin-1 (WFS1) combining optic atrophy, deafness and diabetes mellitus. There is no treatment of WS and patients die around 35 years of age from respiratory or swallowing failure. Recently, we demonstrated that the communication between endoplasmic reticulum (ER) and mitochondria that are tightly connected via the socalled MAM site (for mitochondria-associated membrane) was impaired in WS, leading to mitochondrial deficiency. Our data indeed suggested that it is possible to restore the anomalies by targeting ER-mitochondria function. The sigma-1 receptor (S1R) is a transmembrane protein highly enriched in MAMs. It interacts with several partners involved in ER-mitochondria Ca2+ transfer, thus enhancing Ca2+ efflux from the ER into the mitochondria and improving mitochondrial function. We used the S1R agonist PRE-084 to demonstrate that MAM functional enhancement could be used to restore WS alterations. The PRE-084 treatment restored Ca2+ transfer and mitochondrial respiration in vitro, corrected the associated impaired autophagy and mitophagy and was able to alleviate the behavioral symptoms observed in two genetic animal models of the disease. The unexpected altered auto/mitophagy prompted us to identify binding partner of WFS1. We isolated several partners involved in the regulation of the autophagic process. The project aim is to decipher molecular mechanisms by which WFS1 and S1R regulate neuronal autophagy. Using cellular and in vivo models deficient for WFS1 and S1R, we will confirm the interaction of WFS1 with its preys and evaluate the impact of WFS1 and S1R loss of function on the effects of the preys. In addition, we will determine the role of the proteins on autophagosome formation and transport in neurons. Finally, we will activate S1R with a photoswitchable agonist in different localization of the neuron to determine the precise mechanism of action.