Analysis of Nitrogen Metabolism Related Enzymes and Related Physiological Indexes of Main Foxtail Millet Varieties Developed in North China

[Objectives] This study was conducted to clarify the evolution characteristics of foxtail millet varieties in different ages and provide a basis for the breeding of new varieties. [Methods] A field experiment was carried out on 20 main foxtail millet varieties promoted in North China developed from the 1980 s to 2000 s. The physiological and biochemical indexes of different foxtail millet varieties in four ages were compared, including chlorophyll content, soluble protein content, glutamine synthetase(GS) activity and glutamate synthase(GOGAT) activity, and the correlation between enzyme activity and yield was analyzed. [Results] The chlorophyll SPAD values of the flag leaf and functional leaves of foxtail millet varieties decreased with the filling process. The SPAD values of the flag leaf, top second leaf and top third leaf were higher in the varieties developed in the 1990 s and 2000 s than those in the 1980 s and 2010 s. The activity of glutamine synthetase(GS) and glutamate synthase(GOGAT) showed a single-peak curve in different foxtail millet varieties developed in the recent 30 years, and the peaks of the two were at 7 d and at 7 or 14 d, respectively. The activity of GS and GOGAT increased with the breeding age. In the period from 7 d after anthesis to the mature period, the decreases in the soluble protein content followed an order of 2010 s, 2000 s, 1990 s and 1980 s from small to large, indicating that the degradation rate of various enzyme sources and metabolic regulators in foxtail millet plants decreased during the improvement process. At 35 d after anthesis, the correlation coefficient between GS activity and yield was-0.247, that is, there was a negative correlation with yield. And there was a significant positive correlation between GOGAT activity and yield, and the correlation coefficient was as high as 0.455 at 7 d after anthesis. [Conclusions] Changes in the GS activity, GOGAT activity and soluble protein content in the flag leaf of foxtail millet varieties developed in recent years have a certain impact on yield.

ZC4H2 stabilizes RNF220 to pattern ventral spinal cord through modulating Shh/Gli signaling

ZC4H2 encodes a C4H2 type zinc-finger nuclear factor,the mutation of which has been associated with disorders with various clinical phenotypes in human,including developmental delay,intellectual disability and dystonia.ZC4H2 has been suggested to regulate spinal cord patterning in zebrafish as a co-factor for RNF220,an ubiquitin E3 ligase involved in Gli signaling.Here we showed that ZC4H2 and RNF220 knockout animals phenocopy each other in spinal patterning in both mouse and zebrafish,with mispatterned progenitor and neuronal domains in the ventral spinal cord.We showed evidence that ZC4H2 is required for the stability of RNF220 and also proper Gli ubiquitination and signaling in vivo.Our data provides new insights into the possible etiology of the neurodevelopmental impairments observed in ZC4H2-associated syndromes.

Sequential stabilization of RNF220 by RLIM and ZC4H2 during cerebellum development and Shh-group medulloblastoma progression

Sonic hedgehog (Shh) signaling is essential for the proliferation of cerebellar granule neuron progenitors (CGNPs), and its misregulation is linked to various disorders, including cerebellar cancer medulloblastoma (MB). During vertebrate neural development, RNF220, a ubiquitin E3 ligase, is involved in spinal cord patterning by modulating the subcellular location of glioma-associated oncogene homologs (Glis) through ubiquitination. RNF220 is also required for full activation of Shh signaling during cerebellum development in an epigenetic manner through targeting embryonic ectoderm development. ZC4H2 was reported to be involved in spinal cord patterning by acting as an RNF220 stabilizer. Here, we provided evidence to show that ZC4H2 is also required for full activation of Shh signaling in CGNP and MB progression by stabilizing RNF220. In addition, we found that the ubiquitin E3 ligase RING finger LIM domain-binding protein (RLIM) is responsible for ZC4H2 stabilization via direct ubiquitination, through which RNF220 is also thus stabilized. RLIM is a direct target of Shh signaling and is also required for full activation of Shh signaling in CGNP and MB cell proliferation. We further provided clinical evidence to show that the RLIM‒ZC4H2‒RNF220 cascade is involved in Shh-group MB progression. Disease-causative human RLIM and ZC4H2 mutations affect their interaction and regulation. Therefore, our study sheds light on the regulation of Shh signaling during cerebellar development and MB progression and provides insights into neural disorders caused by RLIM or ZC4H2 mutations.