Ern1-flox Mouse

Ern1, also known as inositol requiring enzyme 1 alpha (IRE1α), is one of the main transducers of the unfolded protein response (UPR) [2]. The UPR is a key intracellular signal transduction pathway activated in response to endoplasmic reticulum (ER) stress, which occurs when misfolded proteins accumulate in the ER lumen [1,3,4,6]. The UPR aims to restore ER homeostasis by regulating the expression of numerous genes, or induce apoptosis if ER stress persists [1,4].

In glioma cells, studies on ERN1 knockdown (a form of loss-of-function experiment) have revealed its role in gene regulation under nutrient deprivations. Glutamine and glucose deprivations affect the expression of pyruvate dehydrogenase genes, homeobox genes, and genes encoding endothelin-1 and its receptors in an ERN1-dependent manner [5,7,8]. For example, ERN1 knockdown modifies the impact of glutamine and glucose deprivations on the expression of PDHA1, PDHB, DLAT, DLD, and PDHX genes [5]. Similarly, it also changes the sensitivity of PAX6, PBX3, PBXIP1, MEIS1, and MEIS2 genes to glucose and glutamine deprivations [7].

In conclusion, Ern1 plays a crucial role in the UPR, which is vital for maintaining ER homeostasis. Through loss-of-function studies in glioma cells, Ern1 has been shown to be involved in regulating gene expression in response to nutrient deprivations. Understanding the function of Ern1 may provide insights into the mechanisms underlying glioma growth and potentially offer new therapeutic strategies for glioma treatment.