| First Author | Balakrishnan B | Year | 2019 |
| Journal | Biochim Biophys Acta Mol Basis Dis | Volume | 1865 |
| Issue | 11 | Pages | 165516 |
| PubMed ID | 31362041 | Mgi Jnum | J:279968 |
| Mgi Id | MGI:6361777 | Doi | 10.1016/j.bbadis.2019.07.010 |
| Citation | Balakrishnan B, et al. (2019) Salubrinal enhances eIF2alpha phosphorylation and improves fertility in a mouse model of Classic Galactosemia. Biochim Biophys Acta Mol Basis Dis 1865(11):165516 |
| abstractText | Loss of galactose-1 phosphate uridylyltransferase (GALT) activity in humans results in Classic Galactosemia, and the GalT-deficient (GalT(-/-)) mouse mimics the patient condition. GalT(-/-) ovaries display elevated endoplasmic reticulum (ER) stress marker, BiP, and downregulated canonical phosphatidylinositol 3-kinase (Pi3k)/protein kinase B (Akt) growth/pro-survival signaling. Numbers of primordial follicles are reduced in the mutants, recapitulating the accelerated ovarian aging seen in human patients. We previously found that oral administration of the compound Salubrinal (an eIF2alpha phosphatase inhibitor), resulted in reduction of ovarian BiP expression, rescued Pi3k/Akt signaling, and a doubling of primordial follicles in GalT(-/-) adults. Here, we further characterized galactosemic stress in GalT(-/-) mice versus wild-type (WT) controls, and examined whether Salubrinal treatment improved broader reproductive parameters. We assessed the expression levels of factors of the unfolded protein response (UPR), and found that BiP, phospho-Perk, and phospho-eIF2alpha were all elevated in GalT(-/-) ovaries. However, neither IKK activation (NFkappaB pathway) nor alternative Xbp1 splicing downstream of ER membrane protein Ire1alpha activation was induced, suggesting an Xbp1-independent UPR in galactosemic stress. Moreover, Salubrinal treatment significantly increased the number of ovulated eggs in mutant animals after gonadotrophic superovulation. Salubrinal treatment also normalized estrus cycle stage lengths and resulted in significantly larger litter sizes than vehicle-treated mutants. Overall, we show that Salubrinal protects against galactosemia-induced primordial follicle loss in a fashion that includes suppressing the de-phosphorylation of eIF2alpha, and that intervention in this way significantly improves and extends ovarian function, fertility, and fecundity. |
