The C-terminal domain of SRA1p has a fold more similar to PRP18 than to an RRM and does not directly bind to the SRA1 RNA STR7 region

The role of estrogen receptors in intracellular estrogen signaling pathways, an overview

To date five members of estrogen receptors (ESRs) have been reported. They are grouped into two classes, the nuclear estrogen receptors are members of the nuclear receptor family which found at nuclear, cytoplasm and plasma membrane, and the membrane estrogen receptors, such as G protein-coupled estrogen receptor 1, ESR-X and Gq-coupled membrane estrogen receptor. The structure and function of estrogen receptors, and interaction between ESR and coregulators were reviewed. In canonical pathway ESRs can translocate to the nucleus, bind to the target gene promotor with or without estrogen responsive element and regulate transcription, mediating the genomic effects of estrogen. Coactivators and corepressors are recruited to activate or inhibit transcription by activated ESRs. Many coactivators and corepressors are recruited to activate or inhibit ESR mediated gene transcription via different mechanisms. ESRs also indirectly bind to the promoter via interaction with other transcription factors, tethering the transcription factors. ESRs can be phosphorylated by several kinases such as p38, extracellular-signal-regulated kinase, and activated protein kinase B, and which activates transcription without ligand binding. Non-genomic estrogen action can be manifested by the increases of cytoplasmic NO and Ca2+ through the activation of membrane ESRs. In female, ESRs signaling is crucial for folliculogenesis, oocyte growth, ovulation, oviduct and uterus. In male, ESRs signaling modulates libido, erectile function, leydig cell steroidogenesis, sertoli cell's function, and epididymal fluid homeostatsis, supporting spermatogenesis and sperm maturation. The abnormal ESRs signaling is believed to be closely related to reproductive diseases and cancer.

Structure of the complete, membrane-assembled COPII coat reveals a complex interaction network

COPII mediates Endoplasmic Reticulum to Golgi trafficking of thousands of cargoes. Five essential proteins assemble into a two-layer architecture, with the inner layer thought to regulate coat assembly and cargo recruitment, and the outer coat forming cages assumed to scaffold membrane curvature. Here we visualise the complete, membrane-assembled COPII coat by cryo-electron tomography and subtomogram averaging, revealing the full network of interactions within and between coat layers. We demonstrate the physiological importance of these interactions using genetic and biochemical approaches. Mutagenesis reveals that the inner coat alone can provide membrane remodelling function, with organisational input from the outer coat. These functional roles for the inner and outer coats significantly move away from the current paradigm, which posits membrane curvature derives primarily from the outer coat. We suggest these interactions collectively contribute to coat organisation and membrane curvature, providing a structural framework to understand regulatory mechanisms of COPII trafficking and secretion.

Humanin induces conformational changes in the apoptosis regulator BAX and sequesters it into fibers, preventing mitochondrial outer-membrane permeabilization

The mitochondrial, or intrinsic, apoptosis pathway is regulated mainly by members of the B-cell lymphoma 2 (BCL-2) protein family. BCL-2-associated X apoptosis regulator (BAX) plays a pivotal role in the initiation of mitochondria-mediated apoptosis as one of the factors causing mitochondrial outer-membrane permeabilization (MOMP). Of current interest are endogenous BAX ligands that inhibit its MOMP activity. Mitochondrial-derived peptides (MDPs) are a recently identified class of mitochondrial retrograde signaling molecules and are reported to be potent apoptosis inhibitors. Among them, humanin (HN) has been shown to suppress apoptosis by inhibiting BAX translocation to the mitochondrial outer membrane, but the molecular mechanism of this interaction is unknown. Here, using recombinant protein expression, along with light-scattering, CD, and fluorescence spectroscopy, we report that HN and BAX can form fibers together in vitro Results from negative stain EM experiments suggest that BAX undergoes secondary and tertiary structural rearrangements and incorporates into the fibers, and that its membrane-associating C-terminal helix is important for the fibrillation process. Additionally, HN mutations known to alter its anti-apoptotic activity affect fiber morphology. Our findings reveal for the first time a potential mechanism by which BAX can be sequestered by fibril formation, which can prevent it from initiating MOMP and committing the cell to apoptosis.

COOLAIR Antisense RNAs Form Evolutionarily Conserved Elaborate Secondary Structures

There is considerable debate about the functionality of long non-coding RNAs (lncRNAs). Lack of sequence conservation has been used to argue against functional relevance. We investigated antisense lncRNAs, called COOLAIR, at the A. thaliana FLC locus and experimentally determined their secondary structure. The major COOLAIR variants are highly structured, organized by exon. The distally polyadenylated transcript has a complex multi-domain structure, altered by a single non-coding SNP defining a functionally distinct A. thaliana FLC haplotype. The A. thaliana COOLAIR secondary structure was used to predict COOLAIR exons in evolutionarily divergent Brassicaceae species. These predictions were validated through chemical probing and cloning. Despite the relatively low nucleotide sequence identity, the structures, including multi-helix junctions, show remarkable evolutionary conservation. In a number of places, the structure is conserved through covariation of a non-contiguous DNA sequence. This structural conservation supports a functional role for COOLAIR transcripts rather than, or in addition to, antisense transcription.

Novel insights into a treatment for aplastic anemia based on the advanced proliferation of bone marrow‑derived mesenchymal stem cells induced by fibroblast growth factor 1

Aplastic anemia (AA) is rare disease that is predominantly observed in adolescents. Without effective management at an early stage, is associated with a high risk of mortality. Bone marrow mesenchymal stem cells (BMSCs) can differentiate into various types of cell, which are able to produce a number of hematopoietic growth factors considered to be important in AA alleviation. However, the mechanism underlying the role of fibroblast growth factor 1 (FGF1) in BMSC differentiation remains unknown. In the current study, the investigation focused on the regulatory role and potential signaling pathway of FGF1 in BMSC differentiation in patients exhibiting AA. BMSCs were infected with Ad‑FGF1 and presented a potent proliferation capability, which was evaluated using Cell Counting kit‑8 analysis. Reverse transcription‑quantitative polymerase chain reaction revealed that long non‑coding (lnc)RNA of testis development related gene 1 (TDRG1) was significantly upregulated, demonstrating high expression at the transcriptional level in the BMSCs that were infected with Ad‑FGF1. The decreased proliferation capability of BMSCs that were treated with Ad‑FGF1 and TDRG1‑small interfering RNA validated the vital effect of TDRG1 on the FGF1 regulatory process of BMSC differentiation. Further experiments revealed that the increase of acetyl‑histones, H3 and H4 was diminished in the TDRG1 promoter of BMSCs that were infected with Ad‑FGF1, which indicated that the process of acetylation was promoted when the BMSCs were infected with Ad-FGF1. Thus, it was inferred that FGF1 induces the proliferation of BMSCs in patients with AA via promoting acetylation in lncRNA of the TDRG1 gene promoter.

Intrinsically disordered proteins in the nucleus of human cells

Intrinsically disordered proteins are known to perform a variety of important functions such as macromolecular recognition, promiscuous binding, and signaling. They are crucial players in various cellular pathway and processes, where they often have key regulatory roles. Among vital cellular processes intimately linked to the intrinsically disordered proteins is transcription, an intricate biological performance predominantly developing inside the cell nucleus. With this work, we gathered information about proteins that exist in various compartments and sub-nuclear bodies of the nucleus of the human cells, with the goal of identifying which ones are highly disordered and which functions are ascribed to the disordered nuclear proteins.