Rnf220 cooperates with Zc4h2 to specify spinal progenitor domains

Abstract

During early embryonic development of the spinal cord, graded sonic hedgehog signaling establishes distinct ventral progenitor domains by regulating the spatiotemporal expression of fate-specifying transcription factors. However, regulation of their protein stability remains incompletely understood. Here, we show that RNF220, an E3 ubiquitin ligase, plays crucial roles in the generation of the ventral progenitor domains, which produce ventral interneurons and motor neurons, by targeting key transcription factors including Dbx1/2 and Nkx2.2 for degradation. Surprisingly, RNF220 interacts with, and is co-expressed with, a zinc-finger protein ZC4H2, and they cooperate to degrade Dbx1/2 and Nkx2.2. RNF220-null mice show widespread alterations of ventral progenitor domains, including the loss of the p2 domain that produces V2 interneurons. Knockdown of RNF220 and ZC4H2 in the chick spinal cord downregulates expression of the V2 interneuronal marker Chx10. Co-expression of RNF220 and ZC4H2 further promotes the ability of Nkx6.1 to induce ectopic Chx10 V2 interneurons. Our results uncover a novel regulatory pathway in establishing distinct progenitor domains through modulating the protein stability of transcription factors. Our results provide insights into the molecular mechanism by which mutations lead to human syndromes characterized by delayed motor development.

Foxd4l1.1 negatively regulates transcription of neural repressor ventx1.1 during neuroectoderm formation in Xenopus embryos

“…Embryos were injected at one-cell stage into animal pole with mRNAs. Injected and un-injected embryos were dissected at stage 9.5 to perform immunofluorescence as described in Lee et al (2018) 58 . Dissected animal caps were fixed in 4% paraformaldehyde for 2 h and incubated in PBSTB (0.5% Triton-X, 2% BSA in PBS) for 1 h. The animal caps were incubated with primary antibody for overnight at 4 °C and washed with PBS.…”

Establishing neuronal diversity in the spinal cord: a time and a place

“…1A). In addition to these transcriptional mechanisms, post-transcriptional regulation of mRNA and protein stability have also been implicated in establishing the correct pattern of NP domains in the spinal cord (Chen et al, 2011;Kim et al, 2018). How morphogen input is converted into distinct progenitor identities is best understood in the context of the ventral neural tube, where Shh signalling specifies progenitor identities in a concentration-and duration-dependent manner (Balaskas et al, 2012;Cohen et al, 2014;Dessaud et al, 2007) (Fig.…”

The Zinc-Finger Domain Containing Protein ZC4H2 Interacts with TRPV4, Enhancing Channel Activity and Turnover at the Plasma Membrane

“…ZC4H2 also contains a nuclear localization signal, and shuttles between the nucleus and the cytosol [20,35]. ZC4H2 has been shown to interact with Smad signaling proteins [23] and with the ubiquitin E3 ligase Rnf220 [22,36], and disease causing mutations may influence the transcriptional regulation of specific genes by these targets, thereby affecting neuronal development. Of note, although zinc-finger-containing proteins are best known in the context of transcription in the nucleus, it is not uncommon that they affect protein function via direct interaction [37].…”

“…At the subcellular level, ZC4H2 partitions between the nucleus and cytoplasm [20]. Expression of ZC4H2 is predominantly found in the brain and central nervous system (CNS) during embryonic development, where it is involved in neuronal development [20,21], possibly via interaction with binding partners, such as Small Mothers Against Decapentaplegic homolog 3 (Smad3) and Ring Finger Protein 220 (RNF220) [22,23]. However, a clear molecular mechanism of ZC4H2 function or dysfunction has not yet been described.…”