Recombinant expression, characterization and phylogenetic studies of novels cystatins-like proteins of sweet orange (Citrus sinensis) and clementine (Citrus clementina)

Polyphenols for Preventing Dental Erosion in Pre-clinical Studies with in situ Designs and Simulated Acid Attack

Dental erosion is a chemical process characterized by acid dissolution of dental hard tissue, and its etiology is multifactorial. Dietary polyphenols can be a strategy for dental erosion management, collaborating to preserve dental tissues through resistance to biodegradation. This study describes a comprehensive review to interpret the effects of polyphenols on dental erosion of pre-clinical models with in situ designs and simulated acid attacks on enamel and dentin samples. We aim to evaluate evidence about Polyphenols' effects in the type of dental substrate, parameters of erosive cycling chosen in the in situ models, and the possible mechanisms involved. An evidence-based literature review was conducted using appropriate search strategies developed for main electronic databases (PubMed, Scopus, Web of Science, LILACS, EMBASE, LIVIVO, CINAHL, and DOSS) and gray literature (Google Scholar). The Joanna Briggs Institute checklist was used to evaluate the quality of the evidence. From a total of 1900 articles, 8 were selected for evidence synthesis, including 224 specimens treated with polyphenols and 224 control samples. Considering the studies included in this review, we could observe that polyphenols tend to promote a reduction in erosive and abrasive wear compared to control groups. However, as the few studies included have a high risk of bias with different methodologies and the estimated effect size is low, this conclusion should not be extrapolated to clinical reality.

Maquiberry Cystatins: Recombinant Expression, Characterization, and Use to Protect Tooth Dentin and Enamel

Phytocystatins are proteinaceous competitive inhibitors of cysteine peptidases involved in physiological and defensive roles in plants. Their application as potential therapeutics for human disorders has been suggested, and the hunt for novel cystatin variants in different plants, such as maqui (Aristotelia chilensis), is pertinent. Being an understudied species, the biotechnological potential of maqui proteins is little understood. In the present study, we constructed a transcriptome of maqui plantlets using next-generation sequencing, in which we found six cystatin sequences. Five of them were cloned and recombinantly expressed. Inhibition assays were performed against papain and human cathepsins B and L. Maquicystatins can inhibit the proteases in nanomolar order, except MaquiCPIs 4 and 5, which inhibit cathepsin B in micromolar order. This suggests maquicystatins' potential use for treating human diseases. In addition, since we previously demonstrated the efficacy of a sugarcane-derived cystatin to protect dental enamel, we tested the ability of MaquiCPI-3 to protect both dentin and enamel. Both were protected by this protein (by One-way ANOVA and Tukey's Multiple Comparisons Test, p < 0.05), suggesting its potential usage in dental products.

Genome-Wide Identification of Sweet Orange WRKY Transcription Factors and Analysis of Their Expression in Response to Infection by Penicillium digitatum

WRKY transcription factors (TFs) play a vital role in plant stress signal transduction and regulate the expression of various stress resistance genes. Sweet orange (Citrus sinensis) accounts for a large proportion of the world's citrus industry, which has high economic value, while Penicillium digitatum is a prime pathogenic causing postharvest rot of oranges. There are few reports on how CsWRKY TFs play their regulatory roles after P. digitatum infects the fruit. In this study, we performed genome-wide identification, classification, phylogenetic and conserved domain analysis of CsWRKY TFs, visualized the structure and chromosomal localization of the encoded genes, explored the expression pattern of each CsWRKY gene under P. digitatum stress by transcriptome data, and made the functional prediction of the related genes. This study provided insight into the characteristics of 47 CsWRKY TFs, which were divided into three subfamilies and eight subgroups. TFs coding genes were unevenly distributed on nine chromosomes. The visualized results of the intron-exon structure and domain are closely related to phylogeny, and widely distributed cis-regulatory elements on each gene played a global regulatory role in gene expression. The expansion of the CSWRKY TFs family was probably facilitated by twenty-one pairs of duplicated genes, and the results of Ka/Ks calculations indicated that this gene family was primarily subjected to purifying selection during evolution. Our transcriptome data showed that 95.7% of WRKY genes were involved in the transcriptional regulation of sweet orange in response to P. digitatum infection. We obtained 15 differentially expressed genes and used the reported function of AtWRKY genes as references. They may be involved in defense against P. digitatum and other pathogens, closely related to the stress responses during plant growth and development. Two interesting genes, CsWRKY2 and CsWRKY14, were expressed more than 60 times and could be used as excellent candidate genes in sweet orange genetic improvement. This study offers a theoretical basis for the response of CSWRKY TFs to P. digitatum infection and provides a vital reference for molecular breeding.

Review: Unraveling the origin of the structural and functional diversity of plant cystatins

The regulation of protease activity is a critical factor for the physiological balance during plant growth and development. Among the proteins involved in controlling protease activity are the cystatins, well-described inhibitors of cysteine proteases present in viruses, bacteria and most Eukaryotes. Plant cystatins, commonly called phytocystatins, display unique structural and functional diversity and are classified according to their molecular weight as type-I, -II, and -III. Their gene structure is highly conserved across Viridiplantae and provides insights into their evolutionary relationships. Many type-I phytocystatins with introns share sequence similarities with type-II phytocystatins. New data shows that they could have originated from recent losses of the carboxy-terminal extension present in type-II phytocystatins. Intronless type-I phytocystatins originated from a single event shared by flowering plants. Pieces of evidence show multiple events of gene duplications, intron losses, and gains throughout the expansion and diversity of the phytocystatin family. Gene duplication events in Gymnosperms and Eudicots resulted in inhibitors with amino acid substitutions that may modify their interaction with target proteases and other proteins. This review brings a phylogenomic analysis of plant cystatin evolution and contributes to a broader understanding of their origins. A complete functional genomic analysis among phytocystatins and their roles in plant development and responses to abiotic and biotic stresses remains a question to be fully solved.

Cystatin-like protein of sweet orange (CsinCPI-2) modulates pre-osteoblast differentiation via β-Catenin involvement

Phytocystatins are endogenous cysteine-protease inhibitors present in plants. They are involved in initial germination rates and in plant defense mechanisms against phytopathogens. Recently, a new phytocystatin derived from sweet orange, CsinCPI-2, has been shown to inhibit the enzymatic activity of human cathepsins, presenting anti-inflammatory potential and pro-osteogenic effect in human dental pulp cells. The osteogenic potential of the CsinCPI-2 protein represents a new insight into plants cysteine proteases inhibitors and this effect needs to be better addressed. The aim of this study was to investigate the performance of pre-osteoblasts in response to CsinCPI-2, mainly focusing on cell adhesion, proliferation and differentiation mechanisms. Together our data show that in the first hours of treatment, protein in CsinCPI-2 promotes an increase in the expression of adhesion markers, which decrease after 24 h, leading to the activation of Kinase-dependent cyclines (CDKs) modulating the transition from G1 to S phases cell cycle. In addition, we saw that the increase in ERK may be associated with activation of the differentiation profile, also observed with an increase in the B-Catenin pathway and an increase in the expression of Runx2 in the group that received the treatment with CsinCPI-2.

Gene expression studies and molecular characterization of a cathepsin L-like from the Asian citrus psyllid Diaphorina citri, vector of Huanglongbing

Huanglongbing (HLB) is a devastating citrus disease associated with Candidatus Liberibacter asiaticus (CLas) and is transmitted by the psyllid Diaphorina citri Kuwayama. Diaphorina citri belongs to Hemiptera order, which has cysteine peptidases as the most abundant proteolytic enzymes present in digestive tract. As cysteine peptidases are involved in different insect development processes, this class of enzymes has acquired biotechnological importance. In this context, we identified a cathepsin L-like (DCcathL1) from the Diaphorina citri transcriptome database and expressed the enzyme in E. coli. Quantitative real-time RT-PCR was conducted to determine DCcathL1 gene expression in different parts and developmental phases of the insect. We observed that DCcathL1 expression in the gut was 2.59 and 2.87-fold higher than in the head and carcass, respectively. Furthermore, DCcathL1 expression was greater in eggs than in nymphs and adults, suggesting a putative role of the enzyme in the embryonic development. In addition, enzymatic inhibitory activity using four recombinant Citrus cystatins were performed. Among them, CsinCPI-2 was the strongest DCcathL1 inhibitor with a Ki value of 0.005 nM. Our results may contribute in the development of strategies for D. citri control, such as silencing the DCcathL1 gene and the use of transgenic plants that overexpress peptidase inhibitors.