MKRN3 regulates the epigenetic switch of mammalian puberty via ubiquitination of MBD3

Abstract

Central precocious puberty (CPP) refers to a human syndrome of early puberty initiation with characteristic increase in hypothalamic production and release of gonadotropin-releasing hormone (GnRH). Previously, loss-of-function mutations in human MKRN3, encoding a putative E3 ubiquitin ligase, were found to contribute to about 30% of cases of familial CPP. MKRN3 was thereby suggested to serve as a ‘brake’ of mammalian puberty onset, but the underlying mechanisms remain as yet unknown. Here, we report that genetic ablation of Mkrn3 did accelerate mouse puberty onset with increased production of hypothalamic GnRH1. MKRN3 interacts with and ubiquitinates MBD3, which epigenetically silences GNRH1 through disrupting the MBD3 binding to the GNRH1 promoter and recruitment of DNA demethylase TET2. Our findings have thus delineated a molecular mechanism through which the MKRN3–MBD3 axis controls the epigenetic switch in the onset of mammalian puberty.

Demethylation of <em>HACE1</em> gene promoter by propofol promotes autophagy of human A549&nbsp;cells

“…In mammalian cells, DNA methylation and demethylation are critical for regulating gene expression levels and serve important roles in physiological and pathological processes, such as mammalian puberty and cancer development ( 32 ). MBD3 induces gDNA demethylation at specific targets and is also involved in maintaining the demethylated and active state of numerous genes, including progonadoliberin-1, serine/threonine-protein kinase Chk2 and 39S ribosomal protein L32, mitochondrial ( 26 , 33 – 35 ). The present findings indicated that propofol promoted expression levels of MBD3 and enhanced its binding to the HACE1 gene promoter.…”

“…ChIP experiments were performed as previously described ( 26 ). Briefly, A549 cells treated in the presence or absence of propofol were crosslinked in 1% formaldehyde (Sigma-Aldrich; Merck KGaA) for 10 min at room temperature, followed by quenching in 125 mM glycine, then washed three times with ice-cold PBS, and resuspended with 270 µl lysis buffer [50 mM Tris-Cl (pH 8.0), 10 mM EDTA, 1% SDS and protease inhibitor].…”

“…2729; Cell Signaling Technology, Inc.), and Protein G agarose beads (Merck KGaA) overnight at 4˚C, washed three and incubated at 65˚C for 30 min. Eluted DNA was adjusted to 300 mM NaCl and incubated at 65˚C for 4 h, followed by incubation at 55˚C for 1 h with 50 µg proteinase K. DNA was purified using the phenol-chloroform method and subjected to the same qPCR analysis as aforementioned (26). Primer sequences are presented in Table II.…”

Makorin rings the kisspeptin bell to signal pubertal initiation

“…Abreu et al demonstrated that the RING finger domain of MKRN3 was obligatory for its ubiquitinase activity, which in turn was required to repress kisspeptin and neurokinin B gene promoters (19). MKRN3 is an E3 ubiquitin ligase, and methyl-CpG-DNA binding protein (MBD3) has recently been identified as a substrate for its E3 ligase activity (20). Additionally, MKRN3-mediated ubiquitination has been reported to disrupt interactions between MBD3 and the GNRH1 promoter to cause epigenetic silencing of GNRH1 expression (which encodes the precursor of GnRH) (20).…”

“…MKRN3 is an E3 ubiquitin ligase, and methyl-CpG-DNA binding protein (MBD3) has recently been identified as a substrate for its E3 ligase activity (20). Additionally, MKRN3-mediated ubiquitination has been reported to disrupt interactions between MBD3 and the GNRH1 promoter to cause epigenetic silencing of GNRH1 expression (which encodes the precursor of GnRH) (20). However, this action may not be exclusive, as MKRN3 has been shown to associate with 81 protein interaction partners, of which 21 are implicated in the determination of pubertal onset (21).…”