Galectin-1 attenuates cardiomyocyte hypertrophy through splice-variant specific modulation of CaV1.2 calcium channel

Pressure overload-induced cardiac hypertrophy occurs in response to chronic blood pressure increase, and dysfunction of Ca_V1.2 calcium channel involves in cardiac hypertrophic processes by perturbing intracellular calcium concentration ([Ca²⁺]_i) and calcium-dependent signaling. As a carbohydrate-binding protein, galectin-1 (Gal-1) is found to bind with Ca_V1.2 channel, which regulates vascular Ca_V1.2 channel functions and blood pressure. However, the potential roles of Gal-1 in cardiac Ca_V1.2 channel (Ca_V1.2_CM) and cardiomyocyte hypertrophy remain elusive. By whole-cell patch clamp, we find Gal-1 decreases the I_Ca,L with or without isoproterenol (ISO) application by reducing the channel membrane expression in neonatal rat ventricular myocytes (NRVMs). Moreover, Gal-1 could inhibit the current densities of Ca_V1.2_CM by an alternative exon 9*-dependent manner in heterologously expressed HEK293 cells. Of significance, overexpression of Gal-1 diminishes ISO or KCl-induced [Ca²⁺]_i elevation and attenuates ISO-induced hypertrophy in NRVMs. Mechanistically, Gal-1 decreases the ISO or Bay K8644-induced phosphorylation of intracellular calcium-dependent signaling proteins δCaMKII and HDAC4, and inhibits ISO-triggered translocation of HDAC4 in NRVMs. Pathologically, we observe that the expressions of Gal-1 and Ca_V1.2_E9* channels are synchronously increased in rat hypertrophic cardiomyocytes and hearts. Taken together, our study indicates that Gal-1 reduces the channel membrane expression to inhibit the currents of Ca_V1.2_CM in a splice-variant specific manner, which diminishes [Ca²⁺]_i elevation, and attenuates cardiomyocyte hypertrophy by inhibiting the phosphorylation of δCaMKII and HDAC4. Furthermore, our work suggests that dysregulated Gal-1 and Ca_V1.2 alternative exon 9* might be attributed to the pathological processes of cardiac hypertrophy, and provides a potential anti-hypertrophic target in the heart.     

The Slowing Rate of CpG Depletion in SARS-CoV-2 Genomes Is Consistent with Adaptations to the Human Host

Depletion of CpG dinucleotides in severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) genomes has been linked to virus evolution, host-switching, virus replication, and innate immune responses. Temporal variations, if any, in the rate of CpG depletion during virus evolution in the host remain poorly understood. Here, we analyzed the CpG content of over 1.4 million full-length SARS-CoV-2 genomes representing over 170 million documented infections during the first 17 months of the pandemic. Our findings suggest that the extent of CpG depletion in SARS-CoV-2 genomes is modest. Interestingly, the rate of CpG depletion is highest during early evolution in humans and it gradually tapers off, almost reaching an equilibrium; this is consistent with adaptations to the human host. Furthermore, within the coding regions, CpG depletion occurs predominantly at codon positions 2-3 and 3-1. Loss of ZAP (Zinc-finger antiviral protein)-binding motifs in SARS-CoV-2 genomes is primarily driven by the loss of the terminal CpG within the motifs. Nonetheless, majority of the CpG depletion in SARS-CoV-2 genomes occurs outside ZAP-binding motifs. SARS-CoV-2 genomes selectively lose CpGs-motifs from a U-rich context; this may help avoid immune recognition by TLR7. SARS-CoV-2 alpha-, beta-, and delta-variants of concern have reduced CpG content compared to sequences from the beginning of the pandemic. In sum, we provide evidence that the rate of CpG depletion in virus genomes is not uniform and it greatly varies over time and during adaptations to the host. This work highlights how temporal variations in selection pressures during virus adaption may impact the rate and the extent of CpG depletion in virus genomes.     

Clinical Significance of Circulating Serum Levels of sCD95 and TNF-α in Cytoprotection of Cervical Cancer

Background:This study correlates the serum levels of sCD95 & TNF-α with a simple cell-based assay to evaluate the capacity of the serum sample to induce apoptosis in Jurkat cells. Interlinking of these parameters can be explored to design a minimum invasive diagnostic strategy for cervical cancer (CC).Methods:Sera samples were assessed to induce apoptosis in Jurkat cells through FACS. Serum levels of sCD95 and TNF-α were measured by ELISA. JNK phosphorylation was evaluated in sera incubated Jurkat cells. Data was scrutinized through statistical analysis.Results:Significantly higher serum levels of sCD95 and lower TNF-α levels were observed in CC patients; their sera samples inhibited induction of apoptosis in Jurkat cells through reduced JNK phosphorylation. Statistical analysis linked these three parameters for the early screening of CC.Conclusion:Distinct sera levels of sCD95 & TNF-α in CC patients showed an anti-apoptotic effect, which can be considered for early detection of CC.Key Words: Apoptosis, sCD95, Jurkat Cells, Tumor Necrosis Factor-alpha, Uterine Cervical Neoplasms     

The structural basis for substrate specificity and inhibition of human S-adenosylmethionine decarboxylase

S-Adenosylmethionine decarboxylase belongs to a small class of amino acid decarboxylases that use a covalently bound pyruvate as a prosthetic group. It is an essential enzyme for polyamine biosynthesis and provides an important target for the design of anti-parasitic and cancer chemotherapeutic agents. We have determined the structures of S-adenosylmethionine decarboxylase complexed with the competitive inhibitors methylglyoxal bis(guanylhydrazone) and 4-amidinoindan-1-one-2'-amidinohydrazone as well as the irreversible inhibitors 5'-deoxy-5'-[N-methyl-N-[(2-aminooxy)ethyl]amino]adenosine, 5'-deoxy-5'-[N-methyl-N-(3-hydrazinopropyl)amino]adenosine, and the methyl ester analogue of S-adenosylmethionine. These structures elucidate residues important for substrate binding and show how those residues interact with both covalently and noncovalently bound inhibitors. S-Adenosylmethionine decarboxylase has a four-layer alphabeta betaalpha sandwich fold with residues from both beta-sheets contributing to substrate and inhibitor binding. The side chains of conserved residues Phe7, Phe223, and Glu247 and the backbone carbonyl of Leu65 play important roles in binding and positioning the ligands. The catalytically important residues Cys82, Ser229, and His243 are positioned near the methionyl group of the substrate. One molecule of putrescine per monomer is observed between the two beta-sheets but far away from the active site. The activating effects of putrescine may be due to conformational changes in the enzyme, to electrostatic effects, or both. The adenosyl moiety of the bound ligand is observed in the unusual syn conformation. The five structures reported here provide a framework for interpretation of S-adenosylmethionine decarboxylase inhibition data and suggest strategies for the development of more potent and more specific inhibitors of S-adenosylmethionine decarboxylase.     

A systemic resistance inducing antiviral protein with N-glycosidase activity from Bougainvillea xbuttiana leaves

An antiviral protein from Bougainvillea xbuttiana leaves induced systemic resistance in host plants N. glutinosa and Cyamopsis tetragonoloba against TMV and SRV, respectively which was reversed by actinomycin D, when applied immediately or shortly after antiviral protein treatment. When the inhibitor was applied to the host plant leaves post inoculation, it was effective if applied upto 4 h after virus infection. It also delayed the expression of symptoms in systemic hosts of TMV. The inhibitor showed characteristic N-glycosidase activity on 25S rRNA of tobacco ribosomes, suggesting that it could also be interfering with virus multiplication through ribosome-inactivation process.     

Improved growth and essential oil yield and quality in Foeniculum vulgare mill on mycorrhizal inoculation supplemented with P-fertilizer

Two arbuscular mycorrhizal (AM) fungi Glomus macrocarpum and Glomus fasciculatum significantly improved growth and essential oil concentration of Foeniculum vulgare Mill. However, AM inoculation of plants along with phosphorus fertilization significantly enhanced growth, P-uptake and essential oil content of plants compared to either of the components applied separately. Among the two fungal inoculants, G. fasciculatum registered the highest growth at both levels of phosphorus used with up to 78% increase in essential oil concentration of fennel seeds over non-mycorrhizal control. The essential oil characterization by gas liquid chromatography revealed that the level of anethol was significantly enhanced on mycorrhization.     

Correcting improper chromosome-spindle attachments during cell division

For accurate segregation of chromosomes during cell division, microtubule fibres must attach sister kinetochores to opposite poles of the mitotic spindle (bi-orientation). Aurora kinases are linked to oncogenesis and have been implicated in the regulation of chromosome-microtubule attachments. Although loss of Aurora kinase activity causes an accumulation of mal-orientated chromosomes in dividing cells, it is not known how the active kinase corrects improper chromosome attachments. The use of reversible small-molecule inhibitors allows activation of protein function in living vertebrate cells with temporal control. Here we show that by removal of small-molecule inhibitors, controlled activation of Aurora kinase during mitosis can correct chromosome attachment errors by selective disassembly of kinetochore-microtubule fibres, rather than by alternative mechanisms involving initial release of microtubules from either kinetochores or spindle poles. Observation of chromosomes and microtubule dynamics with real-time high-resolution microscopy showed that mal-orientated, but not bi-orientated, chromosomes move to the spindle pole as both kinetochore-microtubule fibres shorten, followed by alignment at the metaphase plate. Our results provide direct evidence for a mechanism required for the maintenance of genome integrity during cell division.     

Genetic association analysis of KCNQ3 and juvenile myoclonic epilepsy in a South Indian population

Juvenile myoclonic epilepsy (JME) is a common subtype of idiopathic generalized epilepsy that shows a complex pattern of inheritance. We have tested the association between JME phenotype and an intragenic marker in KCNQ3 by using the transmission disequilibrium test in 119 probands and their parents. Mutations in KCNQ3 are known to cause benign familial neonatal convulsions and are involved in the physiologically important M current in neurons. Our results provide suggestive evidence of allelic association between JME and KCNQ3 (P-value=0.008) and raise an interesting possibility of a genetic contribution to JME, viz., of a gene that causes a monogenic form of human epilepsy.     

EBNA1 partitions Epstein-Barr virus plasmids in yeast cells by attaching to human EBNA1-binding protein 2 on mitotic chromosomes

Epstein-Barr virus (EBV) episomal genomes are stably maintained in human cells and are partitioned during cell division by mitotic chromosome attachment. Partitioning is mediated by the viral EBNA1 protein, which binds both the EBV segregation element (FR) and a mitotic chromosomal component. We previously showed that the segregation of EBV-based plasmids can be reconstituted in Saccharomyces cerevisiae and is absolutely dependent on EBNA1, the EBV FR sequence, and the human EBNA1-binding protein 2 (EBP2). We have now used this yeast system to elucidate the functional contribution of human EBP2 to EBNA1-mediated plasmid partitioning. Human EBP2 was found to attach to yeast mitotic chromosomes in a cell cycle-dependent manner and cause EBNA1 to associate with the mitotic chromosomes. The domain of human EBP2 that binds both yeast and human chromosomes was mapped and shown to be functionally distinct from the EBNA1-binding domain. The functionality and localization of human EBP2 mutants and fusion proteins indicated that the attachment of EBNA1 to mitotic chromosomes is crucial for EBV plasmid segregation in S. cerevisiae, as it is in humans, and that this is the contribution of human EBP2. The results also indicate that plasmid segregation in S. cerevisiae can occur through chromosome attachment.