Daily variations in plasma melatonin and melatonin receptor (MT1), PER1 and CRY1 expression in suprachiasmatic nuclei of tropical squirrel, Funambulus pennanti

The suprachiasmatic nucleus (SCN) plays a major role in photoperiodic regulation of seasonal functions by modulating the melatonin signal. To date no report exists regarding the role of the ambient photoperiod in the regulation of melatonin receptor MT1 and clock gene (PER1 and CRY1) expression in the SCN of any tropical rodent that experiences the least variation in the photoperiod. We noted the expression of MT1, PER1 and CRY1 in the SCN of a tropical squirrel, Funambulus pennanti, along with the plasma level of melatonin over 24 h during the reproductively active (summer) and inactive (winter) phases. The seasonal day length affected the peripheral melatonin, which was inversely related with the MT1 expression in the SCN. The timing for peak expression of PER1 was the same in both phases, while the decline in PER1 expression was delayed by 4 h during the inactive phase. The CRY1 peak advanced by 4 h during the active phase, while the interval between the peak and decline of CRY1 remained the same in both phases. It can be suggested that seasonally changing melatonin levels modulate MT1 expression dynamics in the SCN, altering its functional state, and gate SCN molecular “clock” gene profiles through changes in PER/CRY expression. Such a regulation is important for photo-physiological adaptation (reproduction/immunity) in seasonal breeders.     

A Proteinase K Inhibitor Using α,β-Unsaturated (Dehydro) Residues: A Presumptive Model

Abstract

Enzymes of the subtilisin family, of which proteinase K is a member, have been studied extensively on account of their numerous biological applications. Specific inhibitors of the proteinases are of immense importance in regulating their activity so as to protect the cells against uncontrolled proteolysis. Using the specific design principles of peptides containing dehydro-Alanine (ΔAla), generated by our theoretical calculations, we present here the design of an inhibitor of proteinase K. Energy minimization and molecular modeling of the interaction of the designed tetrapeptide with the recognition site of proteinase K indicate that it is an effective inhibitor.     

Evidence of salicylic acid pathway with EDS1 and PAD4 proteins by molecular dynamics simulation for grape improvement

Biotic stress is a major cause of heavy loss in grape productivity. In order to develop biotic stress-resistant grape varieties, the key defense genes along with its pathway have to be deciphered. In angiosperm plants, lipase-like protein phytoalexin deficient 4 (PAD4) is well known to be essential for systemic resistance against biotic stress. PAD4 functions together with its interacting partner protein enhanced disease susceptibility 1 (EDS1) to promote salicylic acid (SA)-dependent and SA-independent defense pathway. Existence and structure of key protein of systemic resistance EDS1 and PAD4 are not known in grapes. Before SA pathway studies are taken in grape, molecular evidence of EDS1: PAD4 complex is to be established. To establish this, EDS1 protein sequence was retrieved from NCBI and homologous PAD4 protein was generated using Arabidopsis thaliana as template and conserved domains were confirmed. In this study, computational methods were used to model EDS1 and PAD4 and simulated the interactions of EDS1 and PAD4. Since no structural details of the proteins were available, homology modeling was employed to construct three-dimensional structures. Further, molecular dynamic simulations were performed to study the dynamic behavior of the EDS1 and PAD4. The modeled proteins were validated and subjected to molecular docking analysis. Molecular evidence of stable complex of EDS1:PAD4 in grape supporting SA defense pathway in response to biotic stress is reported in this study. If SA defense pathway genes are explored, then markers of genes involved can play pivotal role in grape variety development especially against biotic stress leading to higher productivity.     

Mechanisms Preserving Insulin Action during High Dietary Fat Intake

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Atypical activation of signaling downstream of inactivated Bcr-Abl mediates chemoresistance in chronic myeloid leukemia

Chronic myeloid leukemia (CML) epitomises successful targeted therapy, where inhibition of tyrosine kinase activity of oncoprotein Bcr-Abl1 by imatinib, induces remission in 86% patients in initial chronic phase (CP). However, in acute phase of blast crisis, 80% patients show resistance, 40% among them despite inhibition of Bcr-Abl1 activity. This implies activation of either Bcr-Abl1- independent signalling pathways or restoration of signalling downstream of inactive Bcr-Abl1. In the present study, mass spectrometry and subsequent in silico pathway analysis of differentiators in resistant CML-CP cells identified key differentiators, 14–3-3ε and p38 MAPK, which belong to Bcr-Abl1 pathway. Their levels and activity respectively, indicated active Bcr-Abl1 pathway in CML-BC resistant cells, though Bcr-Abl1 is inhibited by imatinib. Further, contribution of these components to resistance was demonstrated by inhibition of Bcr-Abl1 down-stream signalling by knocking-out of 14–3-3ε and inhibition of p38 MAPK activity. The observations merit clinical validation to explore their translational potential.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12079-021-00647-x.     

Membrane-anchored cytochrome c as an electron carrier in photosynthesis and respiration: past,present and future of an unexpected discovery

In the mid 1980s, it was observed that photosynthesis could still occur in the absence of the diffusible electron carrier cytochrome c ₂ in the purple non-sulfur facultative phototrophic bacterium Rhodobacter capsulatus. This serendipic finding led to the discovery of a novel class of membrane-anchored electron carrier cytochromes and their associated electron transfer pathways. Studies of cytochrome c _y of R. capsulatus (and its homologues in other species) have modified the previous dogma of electron transfer between photosynthetic and respiratory membrane protein complexes with a new paradigm, in which these proteins and their electron carriers can form `hard-wired' structural super-complexes. Here, we reminisce on the early days of this discovery, its impacts on our understanding of cellular energy transduction pathways and the physiological roles played by the electron carrier cytochromes c, and discuss the current knowledge and emerging future challenges of this field. This revised version was published online in August 2006 with corrections to the Cover Date.     

Ro60 peptides induce antibodies to similar epitopes shared among lupus-related autoantigens

The coexistence of autoantibodies to ribonucleoproteins (RNP) in sera of patients with systemic lupus erythematosus has been attributed to intermolecular determinant spreading among physically associated proteins. Recently, we showed that murine Ab responses to rRo60 or Ro60 peptides were diversified unexpectedly to small nuclear RNP. In this investigation, the mechanisms for this autoantibody diversification were examined. Intramolecular determinant spreading was demonstrated in mice immunized with human or mouse Ro60316-335. Immune sera depleted of anti-peptide Ab immunoprecipitated Ro60-associated mY1 and mY3 RNA and remained reactive to a determinant on Ro60128-285. Absorption with the immunogen depleted the immune sera completely of anti-Golgi complex Ab (inducible only with human Ro60316-335) and anti-La Ab, and reduced substantially Ab to SmD and 70-kDa U1RNP. Mouse rRo60 completely inhibited the immune sera reactivity to La, SmD, and 70-kDa U1RNP. However, La, SmD, and 70-kDa U1RNP preferentially inhibited the antiserum reactivities to these Ags, respectively. Affinity-purified anti-La Ab were reactive with Ro60, La, SmD, and 70-kDa U1RNP. These results provide evidence that a population of the induced autoantibodies recognized determinants shared by these autoantigens. Lack of sequence homology between Ro60316-335 and La, SmD, or 70-kDa U1RNP suggests that these determinants are conformational. Interestingly, similar cross-reactive autoantibodies were found in NZB/NZW F1 sera. Thus, a single molecular mimic may generate Ab to multiple RNP Ags. Furthermore, cross-reactive determinants shared between antigenic systems that are not associated physically (Ro/La RNP and small nuclear RNP) may be important in the generation of autoantibody diversity in systemic lupus erythematosus.