High-Throughput Screen Reveals Putative Regulators of MKRN3 in the Hypothalamus

Introduction:

Central precocious puberty (CPP) is often associated with loss-of-function mutations in Makorin Ring Finger Protein 3 (MKRN3). Moreover, hypothalamic MKRN3 mRNA levels decrease before puberty, suggesting its inhibitory role in puberty onset. Although this decrease is well established, the mechanisms that mediate MKRN3 downregulation are unclear.

Aims:

We aim to elucidate the mechanisms that regulate MKRN3 expression in the hypothalamus.

Methods:

In order to find genes whose expression correlates with that of MKRN3, we analysed publicly available RNA datasets from brain samples of rats and mice, and rat mediobasal hypothalami (MBH) through the juvenile to adulthood transition. This might indicate factors that control MKRN3 expression, as well as commonly-regulated factors and downstream targets. As a model for studying the putative MKRN3 regulators, we induced differentiation of human pluripotent stem cells to hypothalamic neural progenitor cells (NPCs).

Results:

The bioinformatic screen identified 26 differentially-expressed genes in the developing rat MBH, whose expression correlated with that of Mkrn3, many of which were differentially expressed also in the brain datasets. Some of these encode transcriptional regulators, which harbor putative binding sites on the MKRN3 promoter. The human NPCs express markers of differentiated neurons such as EMX2, FOXG1 and PAX6 as well as high levels of MKRN3, suggesting that they can be used to study MKRN3 regulation.

Conclusions:

Having identified potential hypothalamic regulators of MKRN3 through analysis of available RNA sequencing data, we are in a position to characterize their roles experimentally using a model of human hypothalamic MKRN3-expressing NPCs.