11 April 2022

Sunday reading (10.04)

Review of scientific periodicals for April 4-10

Georgy Chistov, PCR.news

CAR-T therapy

1. CAR-T therapy continues to develop and refine. A popular direction in this field is the additional activation of the expression of immunoactivating proteins using CAR-T cells. Scientists from Sweden have constructed T-lymphocytes that produce not only a chimeric antigen receptor, but also a neutrophil-activating NAP protein borrowed from the bacterium Helicobacter pylori. The results of the work are published in Nature Biomedical Engineering. The new type of therapy proved to be more effective against solid and heterogeneous tumors than classical CAR-T cells. In mouse models, scientists have shown additional activation of dendritic cells, monocytes, NK cells and neutrophils. The immunogenicity of NAP made it possible to bypass tumor immunosuppression. The effect of such CAR-T therapy persisted even after repeated administration, that is, the host's own immunity did not affect the results of treatment.

2. Another study conducted in China addresses the topic of resistance to CAR-T therapy. Scientists from the General Hospital of the People's Liberation Army of China (Beijing) The genes responsible for sensitivity to this treatment method were identified in B-cell lymphoma. They performed CRISPR screening on a cell line: vectors encoding the Cas9 protein and guide RNAs targeting various genes were delivered to tumor cells. After transfection, the scientists planted lymphocytes to CAR-T cells every three days for 15 days, simulating therapy. If there was a lot of guide RNA to a certain gene in the cell, it means that it was more profitable for the tumor cell to cut out this gene in order to survive. If there was little guide RNA, it means that the target gene contributed to the development of resistance. Scientists have found that the tumor often tries to get rid of the NOXA gene, and its overexpression increases the sensitivity of the cancer cell to therapy. The results obtained in vitro were confirmed in experiments on mice and tumor samples from patients. According to the authors, the concentration of NOXA may be a prognostic marker of the tumor response to CAR-T therapy. The study is published in Signal Transduction and Targeted Therapy.

Sensory organs and systems

3. Leber congenital amaurosis (VLA) is the most common cause of hereditary retinal degeneration in children. In patients with RPE65 gene mutations, cone photoreceptors quickly lose their functions and die off. This leads to early deterioration of vision. Classical methods of gene therapy in the form of delivery of a working copy of a gene have not shown effectiveness in the long term. Scientists from the USA suggested using the adenine editor. They achieved repair in the Rpe65 gene and prolonged the survival of cones in a mouse model of VLA. Subretinal delivery of the gene therapy agent allowed to correct up to 40% of Rpe65 transcripts and restore visual function. Moreover, the researchers found activation of genes associated with cone phototransduction and their survival. Thus, the authors of the work have shown that base editing can become a new treatment method that will provide long-term protection of the retina.

4. Cytoskeletal protein β4-spectrin encoded by the Sptbn4 gene is found in axon nodes and initial segments (axon initial segments, AIS). Sptbn4 mutations are associated with myopathy, neuropathy, and hearing impairment in humans. Scientists from the USA have found that during postnatal development, β4-spectrin plays an important role in clustering potential-dependent sodium channels (Nav) in the Ranvier half-intercept before axon branching. However, it is not important for the formation of Ranvier intercepts on AIS structures in the auditory brainstem. Mice with impaired Sptbn4 function showed no flinching response to noise, despite normal snail function. The authors concluded that the absence of β4-spectrin worsens the clustering of Nav in the half-intercept along the nerve end. This leads to a decrease in the temporal accuracy and reliability of presynaptic spikes. At the level of the body, such problems are expressed in a deficiency of central auditory processing during postnatal development. The results of the study are published in Scientific Reports.


5. Scientists from Japan and the UK have jointly refuted the belief that the dietary supplement S-adenosyl methionine (SAM) is harmless in large quantities to humans. The work is published in Communications Biology. SAM serves as a methyl group donor in various biochemical processes, including the regulation of circadian rhythms. Advertising supplements is often based on the statement "the more, the better", but scientists have shown that this is not the case. They described the negative effects of high concentrations of SAM. In experiments on cell cultures and mice, a large amount of this metabolite led to an elongation of the period of circadian rhythms. Moreover, SAM negatively affected actively dividing cells, suppressing their growth. It turned out that with large amounts, the metabolite begins to decompose by cells to methyladenosine and adenine. They inhibit the enzymes adenosylhomocysteinase and methyltransferase. Scientists believe that the use of SAM without medical supervision can lead to sleep disorders.

6. An international team of scientists forced mice to lose weight with the help of medication. The results of the work are published in Cell Metabolism. Scientists investigated the regulation of the synthesis of hepatokines — special liver proteins involved in communication between organs. In particular, they were interested in hepatokines GDF15 and FGF21. The presence of these proteins in the blood causes the suppression of hunger and stimulates the consumption of lipids by liver cells. The researchers found that in response to various physiological signals, the enzyme CNOT6L deadenylase is activated in the liver. It destroys the mRNA of the GDF15 and FGF21 hepatokines. By screening small molecules, scientists have found a selective inhibitor of this enzyme — iD1. Twice a week, they injected iD1 intraperitoneally into mice with obesity caused by a high-lipid diet. As a result, the weight and appetite of the animals decreased significantly. According to the authors, CNOT6L is a promising target for the treatment of metabolic disorders caused by nutrition.


7. In rare cases, neonatal jaundice associated with the temporary accumulation of bilirubin can lead to brain damage. Effective means of preventing bilirubin metabolism disorders will help prevent such a scenario. Swedish researchers have developed and evaluated a new device that measures bilirubin levels through the skin. The device was named JAISY. Scientists conducted 930 measurements of bilirubin in 141 newborns of different ages, full-term and skin tones. The obtained data were compared with the measurement results of the already proven JM105 instrument. The authors concluded that JAISY accurately and reproducibly measures bilirubin at low and relatively high levels of its content in the blood of full-term and almost full-term infants. The article was published in Scientific Reports.

8. Noninvasive monitoring of respiratory tract inflammation is important in both fundamental and clinical studies. For example, it is possible to evaluate the effectiveness of new drugs in this way. Researchers from Hanover (Germany) we were able to register inflammatory processes in the lungs by analyzing exhaled air. The study involved 10 non-smoking volunteers. The inflammation was modeled by delivering endotoxins locally to specific areas of the lungs or by general inhalation. After the induction of inflammation, the scientists collected exhaled air using a commercially available PExA device and analyzed the particles contained in it. Thus, in both models of inflammation in the early stages, the content of proinflammatory cytokines IL-6 and IL-8 was increased in the exhaled air. The results of the work are published in Scientific Reports.


9. Researchers from China noticed the negative effect of cannabinoids on tumor treatment and reported their observations in Signal Transduction and Targeted Therapy. They analyzed the effect of excipients on chemotherapy in combination with the blockade of immune control points. In mouse models, scientists have shown that both endogenous and exogenous cannabinoids suppress antitumor T-cell immunity. Cannabinoids interact with the CNR2 receptor on the surface of lymphocytes and trigger the JAK/STAT signaling cascade in lymphocytes. This leads to inhibition of CD8+ T cell proliferation. Scientists remind that marijuana is often used as painkillers or to relieve vomiting and nausea caused by chemotherapy. Based on the results obtained, scientists propose to reconsider the use of cannabinoids in chemotherapy in combination with the blockade of immune control points.


10. The environment can contribute to some chemical transformations of biomolecules, for example, the self-cleavage of ribozymes. In proteins, such self-modifications are less common, but directed proteolytic activity can be useful for biotechnology and the development of new therapeutic approaches. Scientists from the UK have developed a method of chemically induced site-selective cleavage of proteins. Their proposed reaction is aimed at readily available residues of dehydroalanine (Dha). Scientists conducted it in water conditions and in cellular lysates. Cleavage requires simple organic reagents that interact with Dha and induce peptide cleavage. Precise chemical proteolysis is carried out without the use of enzymes. The authors propose to use the protocol to remove affine labels and edit the N- and C-ends of the protein.

11. Mutations in the gene of chromodomain-helicase DNA-binding protein 8 (CHD8) are a common cause of autism spectrum disorders. The phenotype associated with these mutations often includes macrocephaly. At the same time, it is not completely clear how the haplon-sufficiency of CHD8 affects the development of the nervous system. A team of scientists from Italy and Austria has created human brain organoids that allowed us to study the functions of the CHD8 gene. Scientists have shown that CHD8 haplon-sufficiency disrupts the development trajectories of the nervous system, accelerating the formation of inhibitory neurons and slowing the development of excitatory ones. This imbalance correlates with macrocephaly in patients. The authors identified specific CHD8-dependent molecular defects associated with abnormal proliferation and alternative splicing in cells. The work is published in Cell Reports.

12. Authors from research centers in Munich (Germany) they proposed a way to make biomaterials from artificial cells read their location and develop accordingly. Similarly, in nature, cells differentiate under the influence of gradients of chemical signals around them. Scientists have created artificial cells: genetic schemes were placed in water droplets in a lipid envelope. The drops were collected in chains that mimic the cellular system. Such "cells" reacted to the gradient of genetic stimuli acting as morphogens in the environment. Scientists managed to divide groups of synthetic cells into two or three regions. Each region expressed reporter genes differently. However, the authors note a limitation due to the properties of the non-cellular expression systems themselves: "cells" did not have time to express genes that trigger signal transmission to neighboring droplets.

Structural Biology

13. Scientists from the USA with the help of cryo-EM deciphered the structure of the PreP protease. It belongs to the class of mitochondrial metalloproteases M16C and regulates protein homeostasis in the organelle. In particular, this enzyme breaks down beta-amyloids and proteins characteristic of the cell nucleus. Cryo-EM data show that PreP is mostly in a semi-open state, but cannot capture the substrate. There are three switch domains in the structure of the enzyme: A, B, and C. The rotation of the switch helix B leads to conformational rearrangements in the switch C. As a result, the enzyme forms a full-fledged pocket for capturing the substrate. The attraction of peptides is facilitated by electrostatic interactions — part of this pocket is negatively charged, while most of the protease substrates are positively charged. The scientists also found hydrophobic interactions between the catalytic pocket and the substrate. The results of the work will be useful for the development of new drugs against amyloidosis and other diseases associated with protein homeostasis.

14. NALCN — Na+ ion leakage channel — regulates the excitability of neurons. Together with the FAM155A, UNC79 and UNC80 proteins, it forms a complex — channelosome. Dysfunction of the NALCN channelosome causes a wide range of neurological and developmental diseases in humans, called channelopathies. Scientists from China have studied the architecture of this complex using mass spectrometry and AlphaFold2. They found out that UNC79 and UNC80 form a super-twisted spiral on the cytoplasmic side of the membrane. Scientists believe that such a structure serves as the basis for binding potential modulators of the channelosome. The UNC79–UNC80 subcomplex is connected to NALCN–FAM155A via a special linker. Violation of any communication within the complex led to disruption of the channel function. Additionally, the scientists found that the protein calmodulin is associated with the channelosome, which is known for its ability to bind calcium and regulate the functions of proteins.

Fundamental Microbiology

15. Horizontal gene transfer can cause rapid shifts in the evolution of bacteria. Mobile genetic elements, including plasmids, allow bacteria to exchange genes within and between species. Plasmids help cells adapt to changing environmental conditions. Nevertheless, foreign plasmids can be dangerous to the host, so the bacteria have developed means of protection against them. Researchers from Switzerland have described two protective systems that have been preserved in Vibrio cholerae El Tor strains responsible for the ongoing seventh cholera pandemic. The genes of the systems are encoded in the islands of pathogenicity characteristic of these strains. The authors of the work showed that protective systems quickly remove small multi-copy plasmids. This mechanism protects the population from infection by bacteriophages, causing the self-destruction of bacterial cells. In addition, the researchers showed that large low-copy foreign plasmids, including those with antibiotic resistance genes, are also destroyed by this system, contributing to the reproduction of cells that do not carry these plasmids. At the same time, it is not entirely clear how cells recognize foreign DNA.

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