Reactive oxygen species, oxidative signaling and the regulation of photosynthesis

Reduction-oxidation (redox) reactions, in which electrons move from a donor to an acceptor, are the functional heart of photosynthesis. It is not surprising therefore that reactive oxygen species (ROS) are generated in abundance by photosynthesis, providing a plethora of redox signals as well as functioning as essential regulators of energy and metabolic fluxes. Chloroplasts are equipped with an elaborate and multifaceted protective network that allows photosynthesis to function with high productivity even in resource-limited natural environments. This includes numerous antioxidants with overlapping functions that provide enormous flexibility in redox control. ROS are an integral part of the repertoire of chloroplast signals that are transferred to the nucleus to convey essential information concerning redox pressure within the electron transport chain. Current evidence suggests that there is specificity in the gene-expression profiles triggered by the different ROS signals, so that singlet oxygen triggers programs related to over excitation of photosystem (PS) II while superoxide and hydrogen peroxide promote the expression of other suites of genes that may serve to alleviate electron pressure on the reducing side of PSI. Not all chloroplasts are equal in their signaling functions, with some sub-populations appearing to have better contacts/access to the nucleus than others to promote genetic and epigenetic responses. While the concept that light-induced increases in ROS result in damage to PSII and photoinhibition is embedded in the photosynthesis literature, there is little consensus concerning the extent to which such oxidative damage happens in nature. Slowly reversible decreases in photosynthetic capacity are not necessarily the result of light-induced damage to PSII reaction centers.

Ticket to a bubble ride: Cargo sorting into exosomes and extracellular vesicles

Extracellular vesicles (EVs) are released by cells into the extracellular milieu to facilitate intercellular communication in both physiological and pathological condition. EVs contain selective repertoires of proteins, RNAs, lipids and metabolites that moderate signalling pathways in the recipient cells. The enrichment of a particular set of proteins or RNAs within the EVs highlights the existence of specific sorting mechanisms that orchestrate the selective packaging of the cargo. The molecular machinery of cargo sorting has remained obscure over the years and functional studies are required to understand this complex mechanism. In this article, we offer a brief overview of the molecular mechanisms that are known to regulate sorting of various molecules into EVs. We also discuss how different pathways of biogenesis alter the exosomal cargo as well and the implications of the cellular state on the content of the EVs. Understanding the sorting of exosomal cargo could further be exploited in clinical settings for targeted drug delivery and to block disease progression.

Sirtuin 5 Regulates Proximal Tubule Fatty Acid Oxidation to Protect against AKI

BACKGROUND

The primary site of damage during AKI, proximal tubular epithelial cells, are highly metabolically active, relying on fatty acids to meet their energy demands. These cells are rich in mitochondria and peroxisomes, the two organelles that mediate fatty acid oxidation. Emerging evidence shows that both fatty acid pathways are regulated by reversible posttranslational modifications, particularly by lysine acylation. Sirtuin 5 (Sirt5), which localizes to both mitochondria and peroxisomes, reverses post-translational lysine acylation on several enzymes involved in fatty acid oxidation. However, the role of the Sirt5 in regulating kidney energy metabolism has yet to be determined.

METHODS

We subjected male Sirt5-deficient mice (either +/- or -/-) and wild-type controls, as well as isolated proximal tubule cells, to two different AKI models (ischemia-induced or cisplatin-induced AKI). We assessed kidney function and injury with standard techniques and measured fatty acid oxidation by the catabolism of 14C-labeled palmitate to 14CO2.

RESULTS

Sirt5 was highly expressed in proximal tubular epithelial cells. At baseline, Sirt5 knockout (Sirt5-/- ) mice had modestly decreased mitochondrial function but significantly increased fatty acid oxidation, which was localized to the peroxisome. Although no overt kidney phenotype was observed in Sirt5-/- mice, Sirt5-/- mice had significantly improved kidney function and less tissue damage compared with controls after either ischemia-induced or cisplatin-induced AKI. This coincided with higher peroxisomal fatty acid oxidation compared with mitochondria fatty acid oxidation in the Sirt5-/- proximal tubular epithelial cells.

CONCLUSIONS

Our findings indicate that Sirt5 regulates the balance of mitochondrial versus peroxisomal fatty acid oxidation in proximal tubular epithelial cells to protect against injury in AKI. This novel mechanism might be leveraged for developing AKI therapies.

Post translational modification of Parkin

Mutations in the gene encoding for the E3 ubiquitin ligase Parkin are associated to a rare form of familiar autosomal recessive Parkinsonism. Despite decades of research on the Parkin protein, whose structure has been recently solved, little is known about the specific signalling pathways that lead to Parkin activation. Parkin activity spans from mitochondria quality control to tumor suppression and stress protection; it is thus tempting to hypothesize that the broad impact of Parkin on cellular physiology might be the result of different post translational modifications that can be controlled by balanced opposing events. Sequence alignment of Parkin from different species indicates high homology between domains across Parkin orthologs and identifies highly conserved amino acid residues that, if modified, impinge on Parkin functions. In this review, we summarize findings on post translational modifications that have been shown to affect Parkin activity and stability.

REVIEWERS

This article was reviewed by Prof. Dr. Konstanze F. Winklhofer and by Prof. Thomas Simmen. Both reviewers have been nominated by Professor Luca Pellegrini.

The impact of histone post-translational modifications in neurodegenerative diseases

Every year, neurodegenerative disorders take more than 5000 lives in the US alone. Cures have not yet been found for many of the multitude of neuropathies. The majority of amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD) and Parkinson's disease (PD) cases have no known genetic basis. Thus, it is evident that contemporary genetic approaches have failed to explain the etiology or etiologies of ALS/FTD and PD. Recent investigations have explored the potential role of epigenetic mechanisms in disease development. Epigenetics comprises heritable changes in gene utilization that are not derived from changes in the genome. A main epigenetic mechanism involves the post-translational modification of histones. Increased knowledge of the epigenomic landscape of neurodegenerative diseases would not only further our understanding of the disease pathologies, but also lead to the development of treatments able to halt their progress. Here, we review recent advances on the association of histone post-translational modifications with ALS, FTD, PD and several ataxias.

HDAC6-dependent deacetylation of AKAP12 dictates its ubiquitination and promotes colon cancer metastasis

Aberrant expression of histone deacetylase 6 (HDAC6) is greatly involved in neoplasm metastasis, which is a leading cause of colon cancer related death. Thus, deep understanding of the regulatory mechanisms of HDAC6 in the metastasis of colon cancer is warranted. In this study, we firstly found that HDAC6 expression was highly expressed in metastatic colon cancer tissues and inhibition or knockdown of HDAC6 suppressed colon cancer metastasis. Next, based on proteomic analysis we uncovered A-kinase anchoring protein 12 (AKAP12) was a novel substrate of HDAC6. HDAC6 interacted with AKAP12 and deacetylated the K526/K531 residues of AKAP12. Moreover, deacetylation of AKAP12 at K531 by HDAC6 increased its ubiquitination level, which facilitated AKAP12 proteasome-dependent degradation. Importantly, we observed an inverse correlation between AKAP12 and HDAC6 protein levels with human colon cancer specimens. Further deletion of AKAP12 in HDAC6 knockdown cells restored the cell motility defects and reactivated the protein kinase C isoforms, repression of which were responsible for the inhibition of cancer metastasis of AKAP12. Our study identified AKAP12 was a new interactor and substrate of HDAC6 and uncovered a novel mechanism through which HDAC6-dependent AKAP12 deacetylation led to its ubiquitination mediated degradation and promoted colon cancer metastasis.

Characterising avenin-like proteins (ALPs) from albumin/globulin fraction of wheat grains by RP-HPLC, SDS-PAGE, and MS/MS peptides sequencing

BACKGROUND

Wheat grain avenin-like proteins (ALPs) belong to a recently discovered class of wheat grain storage protein. ALPs in wheat grains not only have beneficial effects on dough quality but also display antifungal activities, which is a novel observation for wheat storage proteins. Previous studies have shown that ALPs are likely present in the albumin/globulin fractions of total protein extract from wheat flour. However, the accumulation characteristics of these ALPs in the mature wheat grain remains unknown.

RESULTS

In the present study, a total of 13 ALPs homologs were isolated and characterized in the albumin/globulin fractions of the wheat protein extract. A combination of multiple techniques including RP-HPLC, SDS-PAGE, MALDI-TOF and peptide sequencing were used for accurate separation and identification of individual ALP homolog. The C-terminal TaALP-by-4AL/7DS, TaALP-by-4AL/7AS/7DS, TaALP-bx/4AL/7AS/7DS, TaALP-ay-7DS, TaALP-ay-4AL, TaALP-ax-4AL, TaALP-ax-7AS, and TaALP-ax-7DS, were separated as individual protein bands from wheat flour for the first time. These unique ALPs peptides were mapped to the latest wheat genome assembly in the IWGSC database. The characteristic defence related proteins present in albumin and globulin fractions, such as protein disulfide-isomerase (PDI), grain softness protein (GSP), alpha-amylase inhibitors (AAIs) and endogenous alpha-amylase/subtilisin inhibitor were also found to co-segregate with these identified ALPs, avenin-3 and α-gliadins. The molecular weight range and the electrophoresis segregation properties of ALPs were characterised in comparison with the proteins containing the tryp_alpha_amyl domain (PF00234) and the gliadin domain (PF13016), which play a role in plant immunity and grain quality. We examined the phylogenetic relationships of the AAIs, GSP, avenin-3, α-gliadins and ALPs, based on the alignment of their functional domains. MALDI-TOF profiling indicated the occurrence of certain post-translations modifications (PTMs) in some ALP subunits.

CONCLUSIONS

We reported for the first time the complete profiling of ALPs present in the albumin/globulin fractions of wheat grain protein extracts. We concluded that majority of the ALPs homologs are expressed in wheat grains. We found clear evidence of PTMs in several ALPs peptides. The identification of both gliadin domain (PF13016) and Tryp_alpha_amyl domain (PF00234) in the mature forms of ALPs highlighted the multiple functional properties of ALPs in grain quality and disease resistance.

Are nitric oxide-mediated protein modifications of functional significance in diabetic heart? ye'S, -NO', wh'Y-NO't?

Protein modifications effected by nitric oxide (NO) primarily in conjunction with reactive oxygen species (ROS) include tyrosine nitration, cysteine S-nitrosylation, and glutathionylation. The physiological and pathological relevance of these three modifications is determined by the amino acids on which these modifications occur -cysteine and tyrosine, for instance, ranging from altering structural integrity/catalytic activity of proteins or by altering propensity towards protein degradation. Even though tyrosine nitration is a well-established nitroxidative stress marker, instilled as a footprint of oxygen- and nitrogen-derived oxidants, newer data suggest its wider role in embryonic heart development and substantiate the need to focus on elucidating the underlying mechanisms of reversibility and specificity of tyrosine nitration. S-nitrosylation is a covalent modification in specific cysteine residues of proteins and is suggested as one of the ways in which NO contributes to its ubiquitous signalling. Several sensitive and specific techniques including biotin switch assay and mass spectrometry based analysis make it possible to identify a large number of these modified proteins, and provide a great deal of potential S-nitrosylation sites. The number of studies that have documented nitrated proteins in diabetic heart is relatively much less compared to what has been published in the normal physiology and other cardiac pathologies. Nevertheless, elucidation of nitrated proteome of diabetic heart has revealed the presence of many mitochondrial and cytosolic proteins of functional importance. But, the existence of different models of diabetes and analyses at diverse stages of this disease have impeded scientists from gaining insights that would be essential to understand the cardiac complications during diabetes. This review summarizes NO mediated protein modifications documented in normal and abnormal heart physiology including diabetes.

Glycosylation deficiency of lipopolysaccharide-binding protein and corticosteroid-binding globulin associated with activity and response to treatment for rheumatoid arthritis

BACKGROUND

Serum protein glycosylation is an area of investigation in inflammatory arthritic disorders such as rheumatoid arthritis (RA). Indeed, some studies highlighted abnormalities of protein glycosylation in RA. Considering the numerous types of enzymes, monosaccharides and glycosidic linkages, glycosylation is one of the most complex post translational modifications. By this work, we started with a preliminary screening of glycoproteins in serum from RA patients and controls.

METHODS

In order to isolate glycoproteins from serum, lectin wheat germ agglutinin was used and quantitative differences between patients and controls were investigated by LC-MS/MS. Consequently, we focused our attention on two glycoproteins found in this explorative phase: corticosteroid-binding globulin (CBG) and lipopolysaccharide-binding protein (LBP). The subsequent validation with immunoassays was widened to a larger number of early RA (ERA) patients (n = 90) and well-matched healthy controls (n = 90).

RESULTS

We observed a significant reduction of CBG and LBP glycosylation in ERA patients compared with healthy controls. Further, after 12 months of treatment, glycosylated CBG and LBP levels increased both to values comparable to those of controls. In addition, these changes were correlated with clinical parameters.

CONCLUSIONS

This study enables to observe that glycosylation changes of CBG and LBP are related to RA disease activity and its response to treatment.

A Systematic Review on Posttranslational Modification in Proteins: Feature Construction, Algorithm and Webserver

BACKGROUND

Proteins through post translational modifications perform their biological process and cellular functions. Post-translational modifications play important roles in various biological process and cell functions. Identifying the PTMs sites in proteins is very significant to basic research and drug design. Experimental technique to identify post translational modifications is laborious. Computational identification of post translational modifications is a complementary way for its convenience.

CONCLUSION

This review gives the processing to predict post-translational modification sites in proteins including feature construction, algorithms, evaluation measurement, and online webserver. There are two types of post translational modification in proteins. In the prediction of single PTM sites, we transformed it into binary classification learning. While in the prediction of crosstalk PTM sites, we transformed it into multi-label learning. This review summarized the steps on the two issues.

Molecular docking and mechanisms of fusaric acid induced mitochondrial sirtuin aberrations in glycolytically and oxidatively poised human hepatocellular carcinoma (HepG2) cells

Fusaric acid (FA) is a ubiquitous yet neglected mycotoxin. The toxicity of FA is associated with mitochondrial dysfunction and oxidative stress. Sirtuins (SIRTs) are key mediators of cell stress responses through deacetylation of antioxidant, mitochondrial maintenance and energy metabolism proteins. Dietary bioactive compounds have profound effects on SIRT activity, however little is known regarding common foodborne toxins and SIRTs. In this study the interaction of FA with mitochondrial SIRTs - SIRT3 and SIRT5, were firstly studied by molecular docking. Thereafter we substantiated the in silico findings by investigating the effect of FA on expression profiles of SIRT3 and SIRT5, and transcriptional and post-transcriptional regulators, PGC-1α and miRNA-30c using western blots and qPCR in vitro. FA was predicted to bind to the active site of SIRT3 and SIRT5 having implications for biological activity. Furthermore, protein expression of SIRT3 and SIRT5 was down-regulated despite elevated mRNA levels. Further experimentation revealed post-transcriptional regulation of both SIRTs as evidenced by elevated miRNA-30c despite induction of PGC-1α. This study highlights the potential of a diet contaminated with FA to dysregulate mitochondrial specific proteins that can lead to initiation and progression of sirtuin related diseases including cancer and insulin resistance.

ADPRtool: A novel predicting model for identification of ASP-ADP-Ribosylation sites of human proteins

Post-translational modifications (PTMs) occur in the vast majority of proteins, and they are essential for many protein functions. Computational prediction of the residue location of PTMs enhances the functional characterization of proteins. ADP-Ribosylation is an important type of PTM, because it is implicated in apoptosis, DNA repair, regulation of cell proliferation, and protein synthesis. However, mass spectrometric approaches have difficulties in identifying a vast number of protein ADP-Ribosylation sites. Therefore, a computational method for predicting ADP-Ribosylation sites of human proteins seems useful and necessary. Four types of sequence features and an incremental feature selection technique are utilized to predict protein ADP-Ribosylation sites. The final feature set for ADPR prediction modeling is optimized, based on a minimum redundancy maximum relevance criterion, so as to make more accurate predictions on aspartic acid ADPR modified residues. Our prediction model, ADPRtool, is capable to predict Asp-ADP-Ribosylation sites with a total accuracy of 85.45%, which is as good as most computational PTM site predictors. By using a sequence-based computational method, a new ADP-Ribosylation site prediction model - ADPRtool, is developed, and it has shown great accuracies with total accuracy, Matthew's correlation coefficient and area under receiver operating characteristic curve.

AA_stat: Intelligent profiling of in vivo and in vitro modifications from open search results

Characterization of post-translational modifications is among the most challenging tasks in tandem mass spectrometry-based proteomics which has yet to find an efficient solution. The ultra-tolerant (open) database search attempts to meet this challenge. However, interpretation of the mass shifts observed in open search still requires an effective and automated solution. We have previously introduced the AA_stat tool for analysis of amino acid frequencies at different mass shifts and generation of hypotheses on unaccounted in vitro modifications. Here, we report on the new version of AA_stat, which now complements amino acid frequency statistics with a number of new features: (1) MS/MS-based localization of mass shifts and localization scoring, including shifts which are the sum of modifications; (2) inferring fixed modifications to increase method sensitivity; (3) inferring monoisotopic peak assignment errors and variable modifications based on abundant mass shift localizations to increase the yield of closed search; (4) new mass calibration algorithm to account for partial systematic shifts; (5) interactive integration of all results and a rated list of possible mass shift interpretations. With these options, we improve interpretation of open search results and demonstrate the utility of AA_stat for profiling of abundant and rare amino acid modifications. AA_stat is implemented in Python as an open-source command-line tool available at https://github.com/SimpleNumber/aa_stat. SIGNIFICANCE: Mass spectrometry-based PTM characterization has a long history, yet most of the methods rely on a priori knowledge of modifications of interest and do not provide a whole proteome modification landscape in a blind manner. The open database search is an efficient attempt to address this challenge by identifying peptides with mass shifts corresponding to possible modifications. Then, interpreting these mass shifts is required. Therefore, development of bioinformatics software for post-processing of the open search results, which is capable of detection and accurate annotation of new or unexpected modifications, from characterization of sample preparation efficiency and quality control to discovery of rare post-translational modifications, is of high importance.

Neurotoxic or neuroprotective: Post-translational modifications of α-synuclein at the cross-roads of functions

Parkinson's disease is the second most prevalent neurodegenerative disease. The loss of dopaminergic neurons in the substantia nigra is one of the pathological hallmarks of PD. PD also belongs to the class of neurodegenerative disease known as 'Synucleinopathies' as α-synuclein is responsible for disease development. The presence of aggregated α-synuclein associated with other proteins found in the Lewy bodies and Lewy neurites in the substantia nigra and other regions of the brain including locus ceruleus, dorsal vagal nucleus, nucleus basalis of Meynert and cerebral cortex is one of the central events for PD development. The complete biological function of α-synuclein is still debated. Besides its ability to propagate, it undergoes various post-translational modifications which play a paramount role in PD development and progression. Also, the aggregation of α-synuclein is modulated by various post-translational modifications. Here, we present a summary of multiple PTMs involved in the modulation of α-synuclein directly or indirectly and to identify their neuroprotective or neurotoxic roles, which might act as potential therapeutic targets for Parkinson's disease.

Reactive oxygen species, oxidative signaling and the regulation of photosynthesis

Reduction-oxidation (redox) reactions, in which electrons move from a donor to an acceptor, are the functional heart of photosynthesis. It is not surprising therefore that reactive oxygen species (ROS) are generated in abundance by photosynthesis, providing a plethora of redox signals as well as functioning as essential regulators of energy and metabolic fluxes. Chloroplasts are equipped with an elaborate and multifaceted protective network that allows photosynthesis to function with high productivity even in resource-limited natural environments. This includes numerous antioxidants with overlapping functions that provide enormous flexibility in redox control. ROS are an integral part of the repertoire of chloroplast signals that are transferred to the nucleus to convey essential information concerning redox pressure within the electron transport chain. Current evidence suggests that there is specificity in the gene-expression profiles triggered by the different ROS signals, so that singlet oxygen triggers programs related to over excitation of photosystem (PS) II while superoxide and hydrogen peroxide promote the expression of other suites of genes that may serve to alleviate electron pressure on the reducing side of PSI. Not all chloroplasts are equal in their signaling functions, with some sub-populations appearing to have better contacts/access to the nucleus than others to promote genetic and epigenetic responses. While the concept that light-induced increases in ROS result in damage to PSII and photoinhibition is embedded in the photosynthesis literature, there is little consensus concerning the extent to which such oxidative damage happens in nature. Slowly reversible decreases in photosynthetic capacity are not necessarily the result of light-induced damage to PSII reaction centers.

Nuclear Dishevelled: An enigmatic role in governing cell fate and Wnt signaling

The Dishevelled gene was first identified in Drosophila mutants with disoriented hair and bristle polarity and subsequent work has now demonstrated its importance in critical and diverse aspects of biology. Since those early discoveries, Dishevelled has been shown to coordinate a plethora of developmental and cellular processes that range from controlling cell polarity during gastrulation to partnering with chromatin modifying enzymes to regulate histone methylation at genomic loci. While the role of DVL in development is well-respected and the cytosolic function of DVL has been studied more extensively, its nuclear role continues to remain murky. In this review we highlight some of the seminal discoveries that have contributed to the field, but the primary focus is to discuss recent advances with respect to the nuclear role of Dishevelled. This nuclear function of Dishevelled is a dimension which is proving to be increasingly important yet remains enigmatic.

Structural inscrutabilities of Histone (H2BK123) monoubiquitination: A systematic review

Histone H2B monoubiquitination in budding yeast is a highly conserved post-translational modification. It is involved in normal functions of the cells like DNA Repair, RNA Pol II activation, trans-histone H3K and H79K methylation, meiosis, vesicle budding, etc. Deregulation of H2BK123ub can lead to the activation of proto-oncogenes and is also linked to neurodegenerative and heart diseases. Recent discoveries have enhanced the mechanistic underpinnings of H2BK123ub. For the first time, the Rad6's acidic tail has been implicated in histone recognition and interaction with Bre1's RBD domain. The non-canonical backside of Rad6 showed inhibition in polyubiquitination activity. Bre1 domains RBD and RING play a role in site-specific ubiquitination. The role of single Alaline residue in Rad6 activity. Understanding the mechanism of ubiquitination before moving to therapeutic applications is important. Current advancements in this field indicate the creation of novel therapeutic approaches and a foundation for further study.

Endogenous metabolite N-chlorotaurine attenuates antiviral responses by facilitating IRF3 oxidation

Cellular microenvironments critically control the activation of innate immune responses. N-chlorotaurine (Tau-Cl) is an endogenous metabolite that is markedly produced and secreted during pathogenic invasion. However, its effect on the antiviral innate immune responses remains unclear. Here, we demonstrate that viral infection upregulates cellular Tau-Cl level. Tau-Cl attenuates viral infection-induced expression of type I IFNs and facilitates viral replication both in vitro and in vivo. Mechanistically, Tau-Cl facilitates the oxidation of IRF3 at Cys222 and Cys371, a key transcription factor that governs the transcription of type I IFNs. Tau-Cl inhibits phosphorylation and nuclear translocation of IRF3, and blocks IRF3 binding to the IFN-β promoter region. Therefore, we identify Tau-Cl as an endogenous suppressor of IRF3-driven antiviral innate responses and uncover an immune escape mechanism of viruses by affecting host microenvironments.

Insights to the role of phytoconstituents in aiding multi drug resistance - Tuberculosis treatment strategies

Multidrug resistant tuberculosis (MDR-TB) have emerged as a global challenge. There are several underlying mechanisms which are involved in causing mycobacterial resistance towards antitubercular agents including post translational modifications, efflux pumps and gene mutations. This resistance necessitates the investigation of complementary therapeutic options including the use of bioactive compounds from plants. Recent studies have focused on recognising and isolating the characteristics of these compounds to assess their potential against MDR-TB. Phytoconstituents such as alkaloids, flavonoids, terpenoids, glycosides, and essential oils have shown promising antimicrobial activity against Mycobacterium tuberculosis. These compounds can either directly kill or inhibit the growth of M. tuberculosis or enhance the immune system's ability to fight against the infection. Some studies suggest that combining phytoconstituents with standard antitubercular medications works synergistically by enhancing the efficacy of drug, potentially lowering the associated risk of side effects and eventually combating resistance development. This review attempts to elucidate the potential of phytoconstituents in combating resistance in MDR-TB which hold a promise to change the course of treatment strategies in tuberculosis.

Post translational modifications of connexin 43 in ventricular arrhythmias after myocardial infarction

Ventricular arrhythmias are the leading cause of sudden cardiac death in patients after myocardial infarction (MI). Connexin43 (Cx43) is the most important gap junction channel-forming protein in cardiomyocytes. Dysfunction of Cx43 contributes to impaired myocardial conduction and the development of ventricular arrhythmias. Following an MI, Cx43 undergoes structural remodeling, including expression abnormalities, and redistribution. These alterations detrimentally affect intercellular communication and electrical conduction within the myocardium, thereby increasing the susceptibility to post-infarction ventricular arrhythmias. Emerging evidence suggests that post-translational modifications play essential roles in Cx43 regulation after MI. Therefore, Cx43-targeted management has the potential to be a promising protective strategy for the prevention and treatment of post infarction ventricular arrhythmias. In this article, we primarily reviewed the regulatory mechanisms of Cx43 mediated post-translational modifications on post-infarction ventricular arrhythmias. Furthermore, Cx43-targeted therapy have also been discussed, providing insights into an innovative treatment strategy for ventricular arrhythmias after MI.

Characterization of tubulin post-translational modifications and their enzymes during human oocyte meiosis

RESEARCH QUESTION

What are the profiles of tubulin post-translational modifications (PTM) in the meiotic spindles of oocytes with different developmental competence: in-vivo matured MII oocytes (IVO) versus cumulus-free in-vitro matured germinal vesicles (IVM)?

DESIGN

Cumulus-free germinal vesicles were matured in vitro and compared with IVO in terms of their tubulin PTM, characterizing tubulin PTM patterns (acetylation, tyrosination, detyrosination, D2-tubulin formation and polyglutamylation) of their meiotic spindles by immunofluorescence and by evaluation of the expression levels of the enzymes involved by quantitative reverse transcription polymerase chain reaction.

RESULTS

Levels of D2-tubulin, tyrosination and polyglutamylation were similar in IVO and IVM oocytes; acetylation displayed different patterns in both groups, whereas detyrosination was detected only in MII oocytes matured in vivo. The PTM enzyme RNA expression levels in germinal vesicles, IVO and IVM were analysed, as well as in oocytes that failed to mature. Of the 24 PTM enzyme transcripts tested, 17 were present in at least one of the groups under study (aΤΑΤ1, NAA50, HDAC6, SIRT2, TTL, TTLL1, TTLL2, TTLL4, TTLL5, TTLL6, TTLL9, TTLL11, TTLL12, CCP1, CCP5, CCP6, VASH1), of which three were differentially expressed (NAA50, TTLL12, CCP1).

CONCLUSION

All modifications studied were present in human oocytes regardless of whether their meiotic maturation occurred in vivo or in vitro, except for detyrosination, which was found at low levels in the IVO group, but not in the IVM group. This suggests that the presence of tubulin PTMs may play a role in human oocyte maturation, completion of meiosis and developmental competence.

Exploring the Potential of Molecular Spectroscopy for the Detection of Post-translational Modifications of a Stressed Biopharmaceutical Protein

BACKGROUND

Proteins are biomolecules that consist of sequences of amino acids (primary structure) which can further interact and cause the backbone to fold into more complex arrangements (secondary and tertiary structures). Any chemical alterations of the molecules after the translation of the messenger RNA code into a protein primary sequence are known as posttranslational modifications (PTMs). PTMs may affect the protein's functionality; thus it is necessary to identify them. PTMs of particular interest to the pharmaceutical industry include deamidation, oxidation, deglycosylation and isomerization, which may occur due to environmental stressors. However, they have proved challenging to identify quickly. Electronic and vibrational spectroscopies have proved valuable tools for studying higher-order structure and stability of proteins.

METHODS

In this work, circular dichroism (CD), infrared absorbance (IR) and Raman spectroscopies were applied to characterize antibody (mAb NIP 228) PTMs as a result of different stressors. Mass spectrometry was used to confirm the identity of modifications including the targeted ones.

RESULTS

Room temperature CD showed that the secondary structure was the same after all treatments, and temperature-controlled CD showed how protein stability was affected by modifications. Both Raman and IR analysis detected small differences between the reference and deglycosylated proteins, and clearly indicated the presence of other PTMs.

CONCLUSION

This work required some novel computational approaches to pre-process Raman and IR spectra and a review of the band assignments for proteins existing in the literature.

Expanding roles of cross-talk between hydrogen sulfide and nitric oxide under abiotic stress in plants

Abiotic stress such as salt, heavy metals, drought, temperature, and others can affect plants from seed germination to seedling growth to reproductive maturity. Abiotic stress increases reactive oxygen species and lowers antioxidant enzymes in plants resulted the plant tolerance ability against stress conditions decrease. Hydrogen sulfide (H2S) and nitric oxide (NO) are important gasotransmitters involved in seed germination, photosynthesis, growth and development, metabolism, different physiological processes and functions in plants. In plants, various enzymes are responsible for the biosynthesis of both H2S and NO via both enzymatic and non-enzymatic pathways. They also mediate post-translation modification, such as persulfidation, and nitrosylation, which are protective mechanisms against oxidative damage. They also regulate some cellular signalling pathways in response to various abiotic stress. H2S and NO also stimulate biochemical reactions in plants, including cytosolic osmoprotectant accumulation, reactive oxygen species regulation, antioxidant system activation, K+ uptake, and Na+ cell extrusion or vacuolar compartmentation. In this review, we summarize how H2S and NO interact with each other, the function of both H2S and NO, the mechanism of biosynthesis, and post-translational modification under different abiotic stress. Our main emphasis was to find the cross-talk between NO and H2S and how they regulate genes in plants under abiotic stress.

Differential Expression of Neurodegeneration-Related Genes in SH-SY5Y Neuroblastoma Cells Under the Influence of Cyclophilin A: Could the Enzyme be a Likely Trigger and Therapeutic Target for Alzheimer's Disease?

The function and mechanism of Cyclophilin A (CypA) in modulating gene expression associated with Alzheimer's disease (AD) remain unclear. This multifunctional protein is found to be elevated in the cerebrospinal fluid (CSF) of individuals at risk for AD. The cytotoxic effects of CypA, including both wild-type and the mutant R55A, were assessed using the MTT assay. Prior to this evaluation, the purified recombinant protein was validated through enzymatic activity assays and western blot analysis. Following treatment with CypA and transient transfection using the CypA construct, real-time PCR (qRT-PCR) and western blotting were conducted to analyze the expression of factors involved in various signaling pathways, with an emphasis on inflammation, cell death, and intercellular communication. The findings indicate that CypA has a significant impact on the gene expression of factors associated with inflammation and the progression of AD in SH-SY5Y cells. It can be concluded that CypA is capable of regulating gene expression in SH-SY5Y cells, either in a manner dependent on or independent of its enzymatic activity. Additionally, the influence of this multifunctional protein on gene expression is contingent upon the specific site of action, as well as the dosage and duration of exposure to the cells.

Insights on post-translational modifications in fatty liver and fibrosis progression

Metabolic dysfunction-associated steatotic liver disease [MASLD] is a pervasive multifactorial health burden. Post-translational modifications [PTMs] of amino acid residues in protein domains demonstrate pivotal roles for imparting dynamic alterations in the cellular micro milieu. The crux of identifying novel druggable targets relies on comprehensively studying the etiology of metabolic disorders. This review article presents how different chemical moieties of various PTMs like phosphorylation, methylation, ubiquitination, glutathionylation, neddylation, acetylation, SUMOylation, lactylation, crotonylation, hydroxylation, glycosylation, citrullination, S-sulfhydration and succinylation presents the cause-effect contribution towards the MASLD spectra. Additionally, the therapeutic prospects in the management of liver steatosis and hepatic fibrosis via targeting PTMs and regulatory enzymes are also encapsulated. This review seeks to understand the function of protein modifications in progression and promote the markers discovery of diagnostic, prognostic and drug targets towards MASLD management which could also halt the progression of a catalogue of related diseases.