SYNCRIP facilitates porcine parvovirus viral DNA replication through the alternative splicing of NS1 mRNA to promote NS2 mRNA formation

Potential regulatory mechanism and clinical significance of synaptotagmin binding cytoplasmic RNA interacting protein in colorectal cancer

BACKGROUND

Colorectal cancer (CRC) causes many deaths worldwide. Synaptotagmin binding cytoplasmic RNA interacting protein (SYNCRIP) is an RNA-binding protein that plays an important role in multiple cancers by epigenetically targeting some genes. Our study will examine the expression, potential effect, biological function and clinical value of SYNCRIP in CRC.

AIM

To examine the expression, potential effect, biological function and clinical value of SYNCRIP in CRC.

METHODS

The expression of SYNCRIP was examined by immunohistochemistry arrays and high-throughput data. The effect of SYNCRIP gene in CRC cell growth was evaluated by CRISPR-Cas9 technology. The target genes of SYNCRIP were calculated using various algorithms, and the molecular mechanism of SYNCRIP in CRC was explored by mutation analysis and pathway analysis. The clinical value of SYNCRIP in prognosis and radiotherapy was revealed via evidence-based medicine methods.

RESULTS

The protein and mRNA levels of SYNCRIP were both highly expressed in CRC samples compared to nontumorous tissue based on 330 immunohistochemistry arrays and 3640 CRC samples. Cells grew more slowly in eleven CRC cell lines after knocking out the SYNCRIP gene. SYNCRIP could epigenetically target genes to promote the occurrence and development of CRC by boosting the cell cycle and affecting the tumor microenvironment. In addition, CRC patients with high SYNCRIP expression are more sensitive to radiotherapy.

CONCLUSION

SYNCRIP is upregulated in CRC, and highly expressed SYNCRIP can accelerate CRC cell division by exerting its epigenetic regulatory effects. In addition, SYNCRIP is expected to become a potential biomarker to predict the effect of radiotherapy.

Epidemiology and molecular characterization of Feline panleukopenia virus from suspected domestic cats in selected Bangladesh regions

Feline panleukopenia (FPL) is a highly contagious cat disease and is endemic in Bangladesh. The study aims to describe the epidemiology and molecular characterization of the Feline panleukopenia virus from the suspected domestic cats in selected Bangladesh regions. Randomly, 161 rectal swabs were collected from the pet hospitals between July 2021 and December 2022. A structured questionnaire was administered through face-to-face interviews with cat owners in order to collect data on potential risk factors for FPL, such as age, sex, sharing litter boxes and every day utensils in multicat households, vaccination history, hospital visits for other diseases, and season. The rectal swabs were tested by PCR targeting the VP2 capsid protein gene, and six PCR-positive samples were further sequenced for molecular characterizations. The risk factors for FPLV were identified using multivariable logistic regression analysis. The overall prevalence of FPL among suspects was 22.9%. The mortality and case fatality were 10.6%, and 45.9%, respectively. However, mortality in kittens was significantly higher (16.4%) than younger cats. The odds of FPL were 8.83 times (95% CI: 3.14-24.85) higher among unvaccinated cats than vaccinated cats. The winter season had almost six times (95% CI: 1.38-24.40) higher odds of FPL than rainy season. In a multicat house, the odds of FPL was about five times (95% CI: 1.93-13.45) higher for cats that shared a litter box and food utensils compared to those that did not engage in such sharing. Visiting hospitals for other reasons nearly triples the odds of FPL (OR: 2.80, 95% CI: 1.04-7.54) compared to cats that do not visit hospitals. Analysis of partial sequence of the VP2 gene revealed genetic variations among the isolates from different regions. Among these isolates, four were identical to FPLV isolates from South Korea and China, while one showed complete homology with FPLV isolates from Thailand. In contrast, the remaining one was 100% identical to Carnivore protoparvovirus-1 isolated from a feline sample in Italy. Our isolates were classified into three distinct clades alongside Feline panleukopenia virus and Carnivore protoparvovirus-1. One in every three suspected cats was infected with Feline panleukopenia. Regular vaccination of the cats, especially those that share common litter box and food utensils and visit hospitals for other purposes, will help reduce the prevalence of FPL in Bangladesh. Besides, it is worth emphasizing the existence of genetic diversity among the circulating Feline panleukopenia viruses in Bangladesh.

Structure and function of the parvoviral NS1 protein: a review

Parvoviruses possess a single-stranded DNA genome of about 5 kb, which contains two open reading frames (ORFs), one encoding nonstructural (NS) proteins, the other capsid proteins. The NS1 protein contains an N-terminal origin-binding domain, a helicase domain, and a C-terminal transactive domain, and is essential for effective viral replication and production of infectious virus. We first summarize the developments in the structure of NS1 protein, including the original binding domain and the helicase domain. We discuss the role of different DNA substrates in the oligomerization of these two domains of NS1. During the parvovirus life cycle, the NS1 protein is closely related to the viral gene expression, viral replication, and infection. We provide the current understanding of the impact of parvovirus NS1 protein mutations on its biological properties. Overall, in this review, we focus on the structure and function of the parvoviral NS1 protein.

Transcriptional activation of Mink enteritis virus VP2 by the C-terminal of its NS1 protein

Mink enteritis virus (MEV) NS1 is a multidomain and multifunctional protein containing origin binding, helicase, and transactivation domains. In particular, parvoviral NS1 proteins are transactivators of the viral capsid protein promoter although the manner by which they exert these transactivation effects remained unclear. In this study, the region of the transactivation domain of the NS1 C-terminal was found located at aa 557 ~ 668 and any deletion within this region reduced the transactivation activity. A dominant negative mutation of the 63 aa deletion in the C-terminal of NS1 protein resulted in loss of ability to activate P38 and VP2-5'UTR in a dual-luciferase reporter assay system, a VP2 protein expression system, and within the whole MEV genome, independent of downstream genes. Additionally, a full-length MEV clone deficient in its NS1 C-terminal failed to rescue the virus, possibly due to the loss of integrity of DNA sequences interacting with NS1 protein, and expression of VP2 was also inhibited even when normal NS1 protein was supplied in trans.

Inhibition of transcription of VP2 by mutations in the DNA binding domains of mink enteritis virus NS1 protein

The NS1 protein of mink enteritis virus (MEV) is a multidomain and multifunctional protein that plays a critical role in viral replication, with predicted nuclease, helicase and transactivation activities. The nuclease and helicase domains of NS1 protein are involved in interaction with viral DNA. Herein, potential amino acids critical for DNA binding in the MEV NS1 were mutated, all of which resulted in a termination of viral production from an infectious MEV clone. Although E121, H129/131, Y212 and K470/472 mutants retained their P38 and 5'UTR transactivation activity, K196/197 and K406 mutations eliminated this. Interestingly, VP2 protein was produced following transfection of F81 cells with pMEV-NS1-196K2G (K196G and K197G) and pMEV-NS1-K406G when pNS1 was co-transfected in trans, indicating that the substitutions did not affect the integrity of the DNA sequence that bound to NS1 protein but inhibited the biological properties of NS1 protein itself. The ability of NS1 protein to interact with SP1 was inhibited by both 196K2G and K406G substitutions, while 196K2G resulted in failure to bind to the DNA-binding sites in the P38 promoter, and the oligomerization of K406G was inhibited. All of these could explain the transcriptional repression.

Diverse roles of heterogeneous nuclear ribonucleoproteins in viral life cycle

Understanding the host-virus interactions helps to decipher the viral replication strategies and pathogenesis. Viruses have limited genetic content and rely significantly on their host cell to establish a successful infection. Viruses depend on the host for a broad spectrum of cellular RNA-binding proteins (RBPs) throughout their life cycle. One of the major RBP families is the heterogeneous nuclear ribonucleoproteins (hnRNPs) family. hnRNPs are typically localized in the nucleus, where they are forming complexes with pre-mRNAs and contribute to many aspects of nucleic acid metabolism. hnRNPs contain RNA binding motifs and frequently function as RNA chaperones involved in pre-mRNA processing, RNA splicing, and export. Many hnRNPs shuttle between the nucleus and the cytoplasm and influence cytoplasmic processes such as mRNA stability, localization, and translation. The interactions between the hnRNPs and viral components are well-known. They are critical for processing viral nucleic acids and proteins and, therefore, impact the success of the viral infection. This review discusses the molecular mechanisms by which hnRNPs interact with and regulate each stage of the viral life cycle, such as replication, splicing, translation, and assembly of virus progeny. In addition, we expand on the role of hnRNPs in the antiviral response and as potential targets for antiviral drug research and development.