Screening of Lymphoma Radiotherapy-Resistant Genes with CRISPR Activation Library

Objective

The objective of this study was to screen lymphoma radiotherapy-resistant genes using CRISPR activation (CRISPRa).

Methods

The Human CRISPRa library virus was packaged and then transfected into lymphoma cells to construct an activation library cell line, which was irradiated at the minimum lethal radiation dose to screen radiotherapy-resistant cells. Radiotherapy-resistant cell single-guide RNA (sgRNA) was first amplified by quantitative polymerase chain reaction (qPCR) in the coding region and then subject to next-generation sequencing (NGS) and bioinformatics analysis to screen radiotherapy-resistant genes. Certain radiotherapy-resistant genes were then selected to construct activated cell lines transfected with a single gene so as to further verify the relationship between gene expression and radiotherapy resistance.

Results

A total of 16 radiotherapy-resistant genes, namely, C20orf203, MTFR1, TAF1L, MYADM, NIPSNAP1, ZUP1, RASL11A, PSMB2, PSMA6, OR8H3, TMSB4Y, CD300LF, EEF1A1, ATP6AP1L, TRAF3IP2, and SNRNP35, were screened based on the NGS results and bioinformatics analysis of the radiotherapy-resistant cells. Activated cell lines transfected with a single gene were constructed using 10 radiotherapy-resistant genes. The qPCR findings showed that, when compared with the control group, the experimental group had significantly up-regulated mRNA expression of MTFR1, NIPSNAP1, ZUP1, PSMB2, PSMA6, EEF1A1, TMSB4Y and TAF1L (p < 0.05). No significant difference in the mRNA expression of AKT3 or TRAF3IP2 (p > 0.05) was found between the two groups (p > 0.05).

Conclusion

The 16 genes screened are potential lymphoma radiotherapy-resistant genes. It was initially determined that the high expression of 8 genes was associated with lymphoma radiotherapy resistance, and these genes could serve as the potential biomarkers for predicting lymphoma radiotherapy resistance or as new targets for therapy.

[EASL clinical practice guidelines: prevention and treatment of hemorrhage and thrombosis in liver cirrhosis]

Hemorrhage and thrombosis prevention and treatment in patients with cirrhosis faces certain clinical difficulties. Therefore, this guideline is formulated to provide practical guidance on controversial topics, such as the current perspectives on hemostasis in liver disease, whether invasive procedures need to correct thrombocytopenia and coagulation abnormalities, and the necessity of thromboprophylaxis in hospitalized patients with abnormal coagulation. Many of the recommendations in the guidelines are not useful measures; however, they were stem under the oversight of an expert panel, and are widely used in clinical practice. Here, we compile and summarize the recommendations on the above topics in order to share them with readers.

[Baveno VII - Renewing consensus in portal hypertension: personalized care for portal hypertension]

The Baveno VII workshop held in October 2021 was featured by the subject of personalized care in portal hypertension. The workshop focused on the following 9 topics including: the relevance and indications for measuring the hepatic venous pressure gradient as a gold standard; the use of non-invasive tools for the diagnosis of compensated advanced chronic liver disease and clinically significant portal hypertension; the impact of etiological and of non-etiological therapies in the course of cirrhosis; the prevention of the first episode of decompensation; the management of the acute bleeding episode; the prevention of further decompensation; as well as the diagnosis and management of splanchnic vein thrombosis and other vascular disorders of the liver. This essay provides a compilation and summary of recommendations regarding the abovementioned topics, and presents the most recent research proceedings and the corresponding consensus to our readers.

Comparison of strategies for setting intervention thresholds for Chinese postmenopausal women using the FRAX model

PURPOSE

The two main strategies for managing osteoporosis using the Fracture Risk Assessment (FRAX®) are the fixed-probability threshold of the National Osteoporosis Foundation (NOF) and the age-dependent-probability threshold of the National Osteoporosis Guideline Group (NOGG), but there are no FRAX® Chinese-specific thresholds. This study examined the NOF and NOGG strategies for intervention thresholds using the Chinese FRAX® model for their appropriateness for Chinese postmenopausal women, and explored Chinese-specific thresholds.

METHODS

Postmenopausal women (N = 264) >50 years old from community-medical centers in China were randomly selected. They completed a self-report questionnaire and underwent bone mineral density measurements and spinal X-rays. The 10-year risks for a major osteoporosis fracture and hip fracture were calculated using the Chinese FRAX® model. Using an osteoporosis diagnosis as the gold standard, we compared the abilities of the NOF and NOGG thresholds to detect osteoporosis by analyzing their sensitivity, specificity, accuracy, and positive and negative likelihood ratios.

RESULTS

The 10-year risks for hip fracture and a major osteoporotic fracture increased with age. The NOF's accuracy in detecting osteoporosis was 83.33% and the NOGG's was 74.24%. The NOF thresholds showed higher accuracy and specificity than the NOGG thresholds.

CONCLUSION

NOF thresholds are more appropriate for Chinese menopausal women.

Studies of the erythrocyte spectrin tetramerization region

Human erythrocyte spectrin dimers associate at the N-terminal region of alpha spectrin (alpha N) and the C-terminal region of beta-spectrin (beta C) to form tetramers. We have prepared model peptides to study the tetramerization region. Based on phasing information obtained from enzyme digests, we prepared spectrin fragments consisting of the first 156 amino-acid residues and the first 368 amino-acid residues of alpha-spectrin (Sp alpha 1-156 and Sp alpha 1-368, respectively), and found that both peptides associate with a beta-spectrin model peptide, with an affinity similar to that found in alpha beta dimer tetramerization. Spin label EPR studies show that the region consisting of residues 21-46 in alpha-spectrin is helical even in the absence of its beta-partner. Multi-dimensional nuclear magnetic resonance studies of samples with and without a spin label attached to residue 154 show that Sp alpha 1-156 consists of four helices, with the first helix unassociated with the remaining three helices, which bundle to form a triple helical coiled coil bundle. A comparison of the structures of erythrocyte spectrin with other published structures of Drosophila and chicken brain spectrin is discussed. Circular dichroism studies show that the lone helix in Sp alpha-156 associates with helices in the beta peptide to form a coiled coil bundle. Based on NMR and CD results, we suggest that the helices in Sp alpha 1-156 exhibit a looser (frayed) conformation, and that the helices convert to a tighter conformation upon association with its beta-partner. This suggestion does not rule out possible conversion of a non-structured conformation to a structured conformation in various parts of the molecule upon association. Spectrin mutations at residues 28 and 45 of alpha-spectrin have been found in patients with hereditary elliptocytosis. NMR studies were also carried out on Sp alpha 1-156R28S, Sp alpha 1-156R45S and Sp alpha 1-156R45T. A comparison of the structures of Sp alpha 1-156 and Sp alpha 1-156R28S, Sp alpha 1-156R45S and Sp alpha 1-156R45T is discussed.

alpha beta Spectrin coiled coil association at the tetramerization site

On the basis of sequence homology studies, it has been suggested that the association of human erythrocytes alpha and beta spectrin at the tetramerization site involves interactions between helices. However, no empirical details are available, presumably due to the experimental difficulties in studying spectrin molecules because of its size and/or its structural flexibility. It has been speculated that erythrocyte tetramerization involves helical bundling rather than coiled coil association. We have used recombinant spectrin peptides to model alpha and beta spectrin to study their association at the tetramerization site. Two alpha peptides, Sp alpha 1-156 and Sp alpha 1-368, and one beta peptide, Sp beta 1898-2083, were used as model peptides to demonstrate the formation of the alpha beta complex. We also found that the replacement of R28 in Sp alpha 1-368 to give Sp alpha 1-368R28C abolished complex formation with the beta peptide. Circular dichroism techniques were used to monitor the secondary structures of the individual peptides and of the complex, and the results showed that both Sp alpha 1-156 and Sp beta 1898-2083 peptides in solution, separately, included helices that were not paired with other helices in the absence of their binding partners. However, in a mixture of Sp alpha 1-156 and Sp beta 1898-2083 and formation of the alpha beta complex, the unpaired helices associated to form coiled coils. Since the sequences of these two peptides that are involved in the coiled coil association are derived from a native protein, the information obtained from this study also provides insight toward a better understanding of naturally occurring coiled coil subunit-subunit association.