Proline exacerbates hepatic gluconeogenesis via paraspeckle-dependent mRNA retention [RIP-Seq]

Type 2 Diabetes (T2D) is a global health issue characterized by abnormal blood glucose levels and often associated with excessive hepatic gluconeogenesis. Increased circulating non-essential amino acids (NEAAs) are consistently observed in T2D individuals; however, the specific contribution of each amino acid to T2D pathogenesis remains less understood. Here, we reported an unexpected role of the NEAA proline in coordinating hepatic glucose metabolism by modulating paraspeckle, a nuclear structure scaffolded by the long noncoding RNA Neat1. Mechanistically, proline diminished paraspeckles in hepatocytes, liberating the retained mRNA species into cytoplasm for translation, including the mRNAs of Ppargc1a and Foxo1, contributing to enhanced gluconeogenesis and hyperglycemia. We further demonstrated that the proline-paraspeckle-mRNA retention axis existed in diabetic liver samples, and intervening this axis via paraspeckle restoration significantly alleviated hyperglycemia in both female and male diabetic mouse models. Collectively, our results not only delineated a previously unappreciated proline-instigated, paraspeckle-dependent mRNA retention mechanism regulating gluconeogenesis, but also spotlighted proline and paraspeckle as potential targets for managing hyperglycemia. To investigate whether proline stimulation influences mRNA dynamics of paraspeckle in mouse primary hepatocytes (MPH), and the MPH are treated with or without proline treatment. We than used RNA-immunoprecipitation coupled with high-throughput sequencing (RIP-seq) to profile the paraspeckle-retained mRNAs using NONO as a surrogate for paraspeckles.