RBM46 is essential for gametogenesis and functions in post-transcriptional roles affecting meiotic cohesin subunits

RBM46 is a germ cell-specific RNA-binding protein required for gametogenesis, but the targets and molecular functions of RBM46 remain unknown. Here, we demonstrate that RBM46 binds at specific motifs in the 3'UTRs of mRNAs encoding multiple meiotic cohesin subunits and show that RBM46 is required for normal synaptonemal complex formation during meiosis initiation. Using a recently reported, high-resolution technique known as LACE-seq and working with low-input cells, we profiled the targets of RBM46 at single-nucleotide resolution in leptotene and zygotene stage gametes. We found that RBM46 preferentially binds target mRNAs containing GCCUAU/GUUCGA motifs in their 3'UTRs regions. In Rbm46 knockout mice, the RBM46-target cohesin subunits displayed unaltered mRNA levels but had reduced translation, resulting in the failed assembly of axial elements, synapsis disruption, and meiotic arrest. Our study thus provides mechanistic insights into the molecular functions of RBM46 in gametogenesis and illustrates the power of LACE-seq for investigations of RNA-binding protein functions when working with low-abundance input materials.

Rearrangement of T cell receptor genes Tcra and Tcrd and its regulatory mechanism / 中华微生物学和免疫学杂志

The high diversity of T cell receptors (TCRs) is the basis for recognizing antigens, playing an essential role in adaptive immunity. TCR diversity is generated from V(D)J rearrangement during the thymocyte development in the thymus. Standing out from the four TCR genes, Tcra and Tcrd genes are characterized by locating at the same locus and sharing specific V genes. Hence, their rearrangement and regulation have a certain particularity. Previous studies mainly focused on cis-regulatory elements and trans-acting factors regulating the Tcra/ Tcrd rearrangement. However, recent progress has shown that chromatin spatial organization plays an essential role in antigen receptor gene rearrangement. Chromatin organization proteins, such as CTCF-Cohesin, are involved in regulating rearrangement and enhancing the diversity of TCR repertoire by loop extrusion. Recombinase RAG also scans chromatin of antigen receptor genes for rearrangement. This review described the progress in the rearrangement of Tcra and Tcrd genes and the possible regulatory mechanism, especially the influence of the chromatin spatial organization.

Effects of Heyan Kuntai Capsule () on Follicular Development and Oocyte Cohesin Levels in Aged Mice / 中国结合医学杂志

<p><b>OBJECTIVE</b>To evaluate the effect of Heyan Kuntai Capsule (, HYKT) on the ovarian function of aged mice and expressions of cohesion complexes in oocytes.</p><p><b>METHODS</b>Twenty-five 9-month-old female C57BL/6J mice were randomly divided into 5 groups by block randomization method (n=5 per group), including the control group (saline), 17β-estradiol group [E, 100 μg/(kg•d)], and low-, medium-, and highdose of HYKT groups [0.3, 0.9, 2.7 g/(kg•d), respectively]. All mice were treated by intragastric administration for 4 weeks. Hematoxylin and eosin staining and anti-VASA staining were used to detect the amounts of follicles. The apoptosis of follicles was measured by anti-gamma HA histone family member X (γHAX) staining and TdT-mediated dUTP Nick-End Labeling (TUNEL) assay. The density of cohesin subunits, REC8 meiotic recombination protein (REC8), structural maintenance of chromosome (SMC) 1β and SMC3 in oocytes were evaluated by immunofluorescent staining.</p><p><b>RESULTS</b>After administration of E and high-dose of HYKT, the total number of follicles as well as the number of primordial and primary follicles were significantly increased (P<0.05). Anti-γHAX staining and TUNEL assay demonstrated that high-dose of HYKT and E partly suppressed the apoptosis of follicles (P<0.05). Furthermore, it showed an increased trend in the levels of REC8 and SMC1β, after administration with E and HYKT, and no obvious change in the level of SMC3.</p><p><b>CONCLUSION</b>HYKT could enhance the number of follicles, suppress apoptosis of oocytes and have a trend to elevate the meiotic-specific cohesin subunits (REC8 and SMC1β) in oocytes of aged mice, indicating a beneficial effect on the ovarian function in terms of the quantity and quality of follicles.</p>

Identification of hRad21-Binding Sites in Human Chromosome

The aim of this study is to identify hRad21-binding sites in human chromosome, the core component of cohesin complex that held sister chromatids together. After chromatin immunoprecipitation with an hRad21 antibody, it was cloned the recovered DNA and sequenced 30 independent clones. Among them, 20 clones (67%) contained repetitive elements including short interspersed transposable elements (SINE or Alu elements), long terminal repeat (LTR) and long interspersed transposable elements (LINE), fourteen of these twenty (70%) repeats clones had Alu elements, which could be categorized as the old and the young Alu Subfamily, eleven of the fourteen (73%) Alu elements belonged to the old Alu Subfamily, and only three Alu elements were categorized as young Alu subfamily. There is no CpG island within these selected clones. Association of hRad21 with Alu was confirmed by chromatin immunoprecipitation-PCR using conserved Alu primers. The primers were designed in the flanking region of Alu, and the specific Alu element was shown in the selected clone. From these experiments, it was demonstrated that hRad21 could bind to SINE, LTRs, and LINE as well as Alu.