Update of the keratin gene family: evolution, tissue-specific expression patterns, and relevance to clinical disorders

Intermediate filament (IntFil) genes arose during early metazoan evolution, to provide mechanical support for plasma membranes contacting/interacting with other cells and the extracellular matrix. Keratin genes comprise the largest subset of IntFil genes. Whereas the first keratin gene appeared in sponge, and three genes in arthropods, more rapid increases in keratin genes occurred in lungfish and amphibian genomes, concomitant with land animal-sea animal divergence (~ 440 to 410 million years ago). Human, mouse and zebrafish genomes contain 18, 17 and 24 non-keratin IntFil genes, respectively. Human has 27 of 28 type I “acidic” keratin genes clustered at chromosome (Chr) 17q21.2, and all 26 type II “basic” keratin genes clustered at Chr 12q13.13. Mouse has 27 of 28 type I keratin genes clustered on Chr 11, and all 26 type II clustered on Chr 15. Zebrafish has 18 type I keratin genes scattered on five chromosomes, and 3 type II keratin genes on two chromosomes. Types I and II keratin clusters—reflecting evolutionary blooms of keratin genes along one chromosomal segment—are found in all land animal genomes examined, but not fishes; such rapid gene expansions likely reflect sudden requirements for many novel paralogous proteins having divergent functions to enhance species survival following sea-to-land transition. Using data from the Genotype-Tissue Expression (GTEx) project, tissue-specific keratin expression throughout the human body was reconstructed. Clustering of gene expression patterns revealed similarities in tissue-specific expression patterns for previously described “keratin pairs” (i.e., KRT1/KRT10, KRT8/KRT18, KRT5/KRT14, KRT6/KRT16 and KRT6/KRT17 proteins). The ClinVar database currently lists 26 human disease-causing variants within the various domains of keratin proteins.

LDexpress: an online tool for integrating population-specific linkage disequilibrium patterns with tissue-specific expression data

Genome-wide association studies have identified thousands of genetic susceptibility loci associated with cancer as well as other traits and diseases. Mapping germline variation in identified genetic susceptibility regions to alterations in nearby gene expression nominates candidate genes potentially related to disease risk for further functional investigation. We developed LDexpress as an online resource that integrates population-specific linkage disequilibrium data from the 1000 Genomes (1000G) project and tissue-specific expression data from the Genotype-Tissue Expression project to better study regional germline variation impacting gene expression. LDexpress is a publicly available web tool designed to be easy to use, flexible to conduct a wide range of variant queries, and quick to efficiently investigate dozens of query variants across multiple tissue types. We demonstrate the utility of LDexpress using example genomic queries and anticipate this tool will accelerate understanding of disease etiology by uncovering associations of regional germline variation to nearby gene expression.

Genome-wide identification of the tobacco GDSL family and apical meristem-specific expression conferred by the GDSL promoter

Background GDSL esterases/lipases are a large protein subfamily defined by the distinct GDSL motif, and play important roles in plant development and stress responses. However, few studies have reported on the role of GDSLs in the growth and development of axillary buds. This work aims to identify the GDSL family members in tobacco and explore whether the NtGDSL gene contributes to development of the axillary bud in tobacco. Results One hundred fifty-nine GDSL esterase/lipase genes from cultivated tobacco (Nicotiana tabacum) were identified, and the dynamic changes in the expression levels of 93 of these genes in response to topping, as assessed using transcriptome data of topping-induced axillary shoots, were analysed. In total, 13 GDSL esterase/lipase genes responded with changes in expression level. To identify genes and promoters that drive the tissue-specific expression in tobacco apical and axillary buds, the expression patterns of these 13 genes were verified using qRT-PCR. GUS activity and a lethal gene expression pattern driven by the NtGDSL127 promoter in transgenic tobacco demonstrated that NtGDSL127 is specifically expressed in apical buds, axillary buds, and flowers. Three separate deletions in the NtGDSL127 promoter demonstrated that a minimum upstream segment of 235 bp from the translation start site can drive the tissue-specific expression in the apical meristem. Additionally, NtGDSL127 responded to phytohormones, providing strategies for improving tobacco breeding and growth. Conclusion We propose that in tobacco, the NtGDSL127 promoter directs expression specifically in the apical meristem and that expression is closely correlated with axillary bud development.

miR166h Directed Cleavage of Target Upon PGPR Inoculation Under Drought Stress and Tissue-Specific Expression Analysis Under Abiotic Stresses in Chickpea.

Legumes are an indispensable food after cereals with extensive production across the world. The legume production is imposed with limitations and has been augmented by various environmental stresses. The symbiotic relations between legumes and rhizobacteria have been an intriguing topic of research in view of their roles in plant growth, development and various stress responses. Recent advances on gene networks involving plethora of evolutionarily conserved miRNAs have been investigated pertaining to their roles in plant stress responses. The interaction between plant growth promoting rhizobacteria (PGPR) strain Pseudomonas putida RA, MTCC5279 and abiotic stress responsive miRNAs have previously been studied with roles in abiotic stress mitigation by modulating stress responsive miRNAs and their target genes. The present studyis an investigation involving the role of RA in abiotic stress responsive miR166h for drought mitigation in tolerant desi chickpea genotype. miRNA166 directed cleavage of its target, ATHB15 has been drifted of drought treated plantlets upon RA inoculation using 5´RLM-RACE analysis. Drought stressed chickpea plants when inoculated with growth promoting rhizobacteria, RA, the inverse correlation in expression patterns were noticed in miR166h and its validated target, ATHB15. Tissue-specific expression patterns in 15 days old chickpea seedlings including leaves, shoot and roots when exposed to salinity, drought and abscisic acid at different time points indicated the role of miR166 in different abiotic stress response. In view of the results, validation and functional characterization of such interactions involving stress responsive miRNAs along with microbial stress management techniques could be an important technique for crop improvement.

Between Stress and Response: Function and Localization of Mechanosensitive Ca2+ Channels in Herbaceous and Perennial Plants

Over the past three decades, how plants sense and respond to mechanical stress has become a flourishing field of research. The pivotal role of mechanosensing in organogenesis and acclimation was demonstrated in various plants, and links are emerging between gene regulatory networks and physical forces exerted on tissues. However, how plant cells convert physical signals into chemical signals remains unclear. Numerous studies have focused on the role played by mechanosensitive (MS) calcium ion channels MCA, Piezo and OSCA. To complement these data, we combined data mining and visualization approaches to compare the tissue-specific expression of these genes, taking advantage of recent single-cell RNA-sequencing data obtained in the root apex and the stem of Arabidopsis and the Populus stem. These analyses raise questions about the relationships between the localization of MS channels and the localization of stress and responses. Such tissue-specific expression studies could help to elucidate the functions of MS channels. Finally, we stress the need for a better understanding of such mechanisms in trees, which are facing mechanical challenges of much higher magnitudes and over much longer time scales than herbaceous plants, and we mention practical applications of plant responsiveness to mechanical stress in agriculture and forestry.

Genome-wide identification, structural analysis and expression profiles of SRS gene family in quinoa

Based on the whole genome data information of quinoa, the CqSRS gene family members were systematically identified and analyzed by bioinformatics methods, and the responses of CqSRS genes to NaCl (200 mmol/L), SA (200 umol/L) and low temperature (4℃) were detected by qRT-PCR. The results showed that a total of 10 SRS genes were identified in quinoa, and they were distributed on 9 chromosomes, and there were 4 pairs of duplicated genes. The number of amino acids encoded ranged from 143 to 370, and the isoelectric point ranged from 4.81 to 8.90. The secondary structure was mainly composed of random coil(Cc). Most of the CqSRS genes were located in the cytoplasm (5 CqSRS). Phylogenetic analysis showed that the CqSRS gene was divided into three evolutionary groups, and the gene structure showed that the number of exons of CqSRS was between 2–5. Promoter analysis revealed that there are a total of 44 elements related to plant hormone response elements, light response elements, stress response elements and tissue-specific expression in the upstream of the gene. Protein interaction showed that all 10 CqSRS proteins appeared in the known protein interaction network diagram in Arabidopsis. Expression profile analysis showed that CqSRS genes had different expression patterns, and some genes had tissue-specific expression. qRT-PCR showed that all SRS family genes responded to SA, NaCl and low-temperature treatments, but the expression levels of different CqSRS genes were significantly different under various stresses. This study lays a foundation for further analyzed the function of CqSRS family genes.