Publications by authors named "Vita Levina"

Histone modifications are associated with distinct transcriptional states, but it is unclear whether they instruct gene expression. To investigate this, we mutate histone H3.3 K9 and K27 residues in mouse embryonic stem cells (mESCs).

View Article and Find Full Text PDF
Article Synopsis
  • Chromatin compaction is a key mechanism in gene repression, traditionally believed to limit transcription by reducing chromatin accessibility.
  • Using cryo-electron tomography, researchers mapped the 3D structure of chromatin compacted by the Polycomb Repressive Complex 1 (PRC1) and CBX8, revealing that this complex is porous and stabilized by dynamic interactions.
  • The findings suggest that PRC1-chromatin condensates are not rigidly compacted, but instead remain dynamic and accessible in differentiated mouse embryonic stem cells, challenging previous assumptions about Polycomb domains.
View Article and Find Full Text PDF

Gonadotropin-releasing hormone (GnRH) and its synthetic analogues are considered banned substances by the racing industry. GnRH is used as a pharmaceutical to regulate the female oestrous cycle, but the hormone is also thought to increase the production of testosterone in male animals. Using liquid chromatography in conjunction with high-resolution mass spectrometry (LC-HRMS) and data-independent acquisition (DIA), a method is presented for the detection of intact and truncated peptides of GnRH and its analogues down to the low picogram level in equine urine.

View Article and Find Full Text PDF

A synthetic Interleukin-1 receptor antagonist peptide with the sequence Acetyl-Phe-Glu-Trp-Thr-Pro-Gly-Tyr-Trp-Gln-Pro-Tyr-Ala-Leu-Pro-Leu-OH has been identified in a vial seized during a stable inspection. The use of peptide-based Interleukin-1 receptor antagonists as anti-inflammatory agents has not been previously reported, making this peptide the first in a new class of sports doping peptides. The peptide has been characterized by high-resolution mass spectrometry and a detection method developed based on solid-phase extraction and liquid chromatography - triple quadrupole mass spectrometry.

View Article and Find Full Text PDF

The cytokine TWEAK and its cognate receptor Fn14 are members of the TNF/TNFR superfamily and are upregulated in tumors. We found that Fn14, when expressed in tumors, causes cachexia and that antibodies against Fn14 dramatically extended lifespan by inhibiting tumor-induced weight loss although having only moderate inhibitory effects on tumor growth. Anti-Fn14 antibodies prevented tumor-induced inflammation and loss of fat and muscle mass.

View Article and Find Full Text PDF

The growth hormone releasing peptides (GHRPs) hexarelin, ipamorelin, alexamorelin, GHRP-1, GHRP-2, GHRP-4, GHRP-5, and GHRP-6 are all synthetic met-enkephalin analogues that include unnatural D-amino acids. They were designed specifically for their ability to stimulate growth hormone release and may serve as performance enhancing drugs. To regulate the use of these peptides within the horse racing industry and by human athletes, a method is presented for the extraction, derivatization, and detection of GHRPs from equine and human urine.

View Article and Find Full Text PDF

Intronic expansion of a hexanucleotide GGGGCC repeat in the chromosome 9 open reading frame 72 (C9ORF72) gene is the major cause of familial amyotrophic lateral sclerosis (ALS) and frontotemporal dementia. However, the cellular function of the C9ORF72 protein remains unknown. Here, we demonstrate that C9ORF72 regulates endosomal trafficking.

View Article and Find Full Text PDF

The Dermorphins are a family of peptides that act as potent agonists of the opioid μ receptor. Originally identified as a seven amino acid peptide on the skin of the South American Phyllomedusa frog, peptide chemists have since developed a large number of Dermorphin variants, many with superior opioid activity to the original peptide. Dermorphins are unique among the peptide opioid agonists as they appear to have a limited ability to cross the blood brain barrier, producing effects on both the central and peripheral nervous systems.

View Article and Find Full Text PDF

Protein disulfide isomerase (PDI) family members are important enzymes for the correct folding and maturation of proteins that transit or reside in the endoplasmic reticulum (ER). The human PDI family comprises at least 19 members that differ in cell type expression, substrate specificity and post-translational modifications. PDI family A member 2 (PDIA2, previously known as PDIp) has a similar domain structure to prototypical PDI (also known as PDIA1), but the function and post-translational modifications of PDIA2 remain poorly understood.

View Article and Find Full Text PDF

Many insect viruses express caspase inhibitors of the P35 superfamily, which prevent defensive host apoptosis to enable viral propagation. The prototypical P35 family member, AcP35 from Autographa californica M nucleopolyhedrovirus, has been extensively studied. Bacterially purified AcP35 has been previously shown to inhibit caspases from insect, mammalian and nematode species.

View Article and Find Full Text PDF

Yeast are a valuable system for recombinant serpin production due to their ability to synthesize large amounts of heterologous gene products as well as their expression of folding chaperones and lack of endogenous serpin genes. In this chapter, we describe a method for intracellular expression of cytoplasmic serpins in the yeast Pichia pastoris. We also give details on how this system can be exploited to produce polymer-forming mutants of secretory serpins.

View Article and Find Full Text PDF

Many bacterial pathogens produce extracellular proteases that degrade the extracellular matrix of the host and therefore are involved in disease pathogenesis. Dichelobacter nodosus is the causative agent of ovine footrot, a highly contagious disease that is characterized by the separation of the hoof from the underlying tissue. D.

View Article and Find Full Text PDF

The serpinopathies encompass a large number of diseases caused by inappropriate conformational change and self-association (polymerization) of a serpin (serine proteinase inhibitor) molecule. The most common serpinopathy is alpha(1)-antitrypsin (alpha(1)AT) deficiency, which is associated with an increased risk for liver cirrhosis, hepatocellular carcinoma and early-onset emphysema. The Z variant of alpha(1)AT, which accounts for 95% of all cases of alpha(1)AT deficiency, polymerizes during synthesis and after secretion.

View Article and Find Full Text PDF
Article Synopsis
  • Alpha(1)-antitrypsin (alpha(1)AT) is a crucial protein that helps protect the lungs, and its deficiency can lead to severe health issues like emphysema and liver diseases.
  • The Z variant of alpha(1)AT, a specific genetic mutation, causes misfolding and makes it difficult to produce the protein for research.
  • Researchers have successfully produced monomeric and active recombinant Z alpha(1)AT from yeast, which could help in understanding its polymerization and developing potential treatments.
View Article and Find Full Text PDF