Evolution of Trichocyte Keratin Associated Proteins

The Identification of a New Gene KRTAP 6-3 in Capra hircus and Its Potential for the Diameter Improvement of Cashmere Fibers

BACKGROUND

Cashmere is one of the important economic products of goats, and the KRTAP gene family, as an important family of regulatory genes in the growth process of cashmere fiber, largely affects the quality of cashmere.

METHODS

In this study, the KRTAP6-3 gene was identified and located on goat chromosome 1 using a goat genome homology search combined with a phylogenetic tree approach. The Longdong cashmere goat KRTAP6-3 gene variation and its effect on cashmere quality were explored by using the polymerase chain reaction single-stranded conformation polymorphism (PCR-SSCP) technique, in situ hybridization, and the allele presence/absence model.

RESULTS

The results identified a total of six SNPs in KRTAP6-3, three of which were located in the coding region and two of which were synonymous mutations, in addition to 45- bp deletion sequences detected in alleles C and F. Moreover, the KRTAP6-3 mRNA showed a strong expression signal in the cortical layer of the primary and secondary follicles in the inner root sheaths, as well as in the cells of the hair papillae and the matrices during the anagen phase, and signaling at the sites described above is attenuated during the telogen phase. The presence of allele C was associated with increased MFD (mean fiber diameter) (p < 0.01). The MFD of goats with allele C genotype (genotype AC) was significantly higher (p < 0.05) than that of goats without allele C genotype (genotypes AA and AB).

CONCLUSIONS

This indicates that genetic variation in the KRTAP6-3 gene in goats is significantly associated with cashmere traits and can serve as a candidate gene for molecular markers of cashmere traits.

Biocompatibility and wound-healing prospect of KAPs-depleted residual hair biomaterial

This work is an in-depth investigation of the in vitro and in vivo biocompatibility of processed and treated residual human hair samples with intact cuticle layers. The specimens included oxidized hair with minimal melanin (BLH) and hair with medium- (M-KAP) and low- (L-KAP) amounts of keratin associated proteins (KAPs), confirmed through gel electrophoresis, electron microscopy, trichrome histological staining, and tensile biomechanics, in comparison to the untreated regular hair (REG) control. All hair groups, high KAPs (H-KAPs: REG and BLH), M-KAP, and L-KAP, are non-cytotoxic in the adipose fibroblast's response to their extracts based on the ISO 10993-5 medical device biomaterial testing standard. In vivo mouse subcutaneous implantation (ISO 10993-6, local effects) at 2 weeks showed a foreign body response (FBR) with thin fibrous encapsulation at 28% relative skin dermis thickness; but the L-KAP implant mitigated a significant decrease in FBR area compared to H-KAPs and a lower number of immune cells of mostly macrophages and mast cells on the biomaterial's surface. In the bulk of the capsules, blood vessels and collagen extracellular matrix densities were similar among groups. These findings suggest that small globular KAPs diffuse out of the cortex to the host-biomaterial interface which induce a slightly-elevated FBR but limited to the implant's surface vicinity. For translatability, we evaluated the effectiveness of the residual hair with the most depleted KAPs (L-KAP) in a 10 mm-diameter, splinted, and full-thickness mouse skin excision wound. Treatment with the L-KAP mesh exhibited an 8% healing improvement per day compared to the untreated control: significantly reducing the projected complete healing time by 30%. On-going research focuses on purer keratin-based and macromolecularly organized residual hair biomaterials for drug-delivery as they are deemed the most biocompatible.

Cornified Epithelial Teeth of Jawless Vertebrates Contain Proteins Similar to Keratin-Associated Proteins of Mammalian Skin Appendages

Keratins and keratin-associated proteins (KRTAPs) are the main components of mammalian nails and hair. Comparative genomics and gene expression studies have revealed that keratins are conserved in all vertebrates, whereas KRTAPs exist only in mammals. Recently, we found hair keratin-like cysteine-rich keratins in jawless vertebrates with confirmed expression in the cornified epithelial teeth of the sea lamprey (Petromyzon marinus). Here, we report that KRTAP-like proteins are also present in the horny teeth of the lamprey. Mass spectrometry-based proteomics identified proteins that share features with KRTAPs, such as high contents of cysteine and tyrosine residues, which support intermolecular interactions, and abundant glycine residues, which endow the proteins with flexibility. Genes encoding KRTAP-like proteins are arranged in a cluster in P. marinus, and the presence of at least one KRTAP-like protein is conserved in phylogenetically diverse species of lamprey, including Lampetra fluviatilis, Lethenteron reissneri, Geotria australis, and Mordacia mordax. The KRTAP-like genes of lampreys contain two exons, whereas mammalian KRTAPs have only a single exon. Although KRTAPs and KRTAP-like proteins are products of independent evolution, their common expression in cornified skin appendages suggests that they fulfill similar functions.

Skin Appendage Proteins of Tetrapods: Building Blocks of Claws, Feathers, Hair and Other Cornified Epithelial Structures

Reptiles, birds, mammals and amphibians, together forming the clade tetrapods, have a large diversity of cornified skin appendages, such as scales, feathers, hair and claws. The skin appendages consist of dead epithelial cells that are tightly packed with specific structural proteins. Here, we review the molecular diversity and expression patterns of major types of skin appendage proteins, namely keratin intermediate filament proteins, keratin-associated proteins (KRTAPs) and proteins encoded by genes of the epidermal differentiation complex (EDC), including corneous beta-proteins, also known as beta-keratins. We summarize the current knowledge about the components of skin appendages with a focus on keratins and EDC proteins that have recently been identified in reptiles and birds. We discuss gaps of knowledge and suggest directions of future research.

Global gene expression profile of proliferative verrucous leukoplakia and its underlying biological disease mechanisms

BACKGROUND

Proliferative verrucous leukoplakia (PVL) is a rare and enigmatic oral potentially malignant disorder which almost invariably results in oral squamous cell carcinoma (OSCC). The aims of this project were to use transcriptome profiling to characterise PVL gene expression patterns for biomarker identification and gain insight into the molecular aetiopathogenesis of PVL.

METHODS

Forty-three oral cavity mucosal biopsies from 32 patients with oral lesions clinically compatible with either PVL or non-PVL conventional oral leukoplakia (OLK) underwent transcriptome profiling by RNA sequencing. Data was analysed by hierarchical clustering, differential gene expression, functional enrichment and network analysis, sparse partial least squares discriminant analysis sPLS-DA, and immune cell phenotypic estimation.

RESULTS

We found 464 genes significantly differentially expressed at least 2-fold between PVL and non-PVL OLK (193 up and 271 down). HOX genes, including HOXA1 and HOXB7, keratin-associated proteins (KRTAPs) and olfactory receptor G proteins (OR) were significantly upregulated in PVL. Other upregulated genes in PVL included FOS, WNT16 and IFNA1. Pathway analysis showed that there was a significant downregulation of connective tissue signalling in PVL. Classifying multivariate models based upon 22 genes discriminated PVL from non-PVL OLK. Bioinformatic profiling showed that immune cell profiles in PVL and OLK were similar except that fibroblast markers were reduced in PVL.

CONCLUSION

These results demonstrate that PVL and conventional OLK are molecularly distinct with upregulation of many cancer-associated genes. They provide insight into the pathogenesis of PVL and show that biomarker based molecular diagnostics is feasible to discriminate and inform diagnosis and management.

A study of the phosphorylation proteomic skin characteristics of Tan sheep during the newborn and er-mao stages

In this experiment, in order to study the formation mechanism of the lamb fur of Tan sheep, skin samples were collected from Tan sheep at the newborn and er-mao stages. Then, the phosphorylated proteomes of the skin samples of Tan sheep at the two different stages were compared and analyzed using a TMT labeled quantitative phosphorylation proteomic technique. A total of 2806 phosphorylated proteins were identified, including 8184 phosphorylation sites. The results of this study’s quantitative analysis showed that when compared with the skin samples at the er-mao stage, the phosphorylation levels of 171 sites had been upregulated in the skin samples at newborn stage. Meanwhile, 125 sites had been downregulated at the same stage. As shown by the results of the functional enrichment analysis of the differentially phosphorylated proteins, they had been mainly enriched in the cysteine and methionine metabolism. In addition, the phosphorylation levels of KAP4.7 and KAP13.1 had also varied during the different skin stages. These results indicated that the cysteine metabolism pathways, as well as the phosphorylation modifications of the keratin associated proteins in the skin, played important roles in the formation of the er-mao stage fur of the Tan sheep. Therefore, the findings of this study provided a new angle for interpreting the formation mechanism of er-mao stage fur properties.

Association analysis for SNPs of KRT26 and TCHH genes with cashmere production performance, body measurement traits and milk production traits in Liaoning cashmere goats

Cashmere fineness is getting thicker, which is one of the key problems in cashmere breeding, however, there have been no systematic studies on the molecular regulation of cashmere fineness. The aim of this study was to investigate the relationship between KRT26 and TCHH gene polymorphism and production performance in Liaoning cashmere goats (LCG). The potential single nucleotide polymorphisms (SNPs) of LCG were detected by sequence alignment and PCR-Seq polymorphism of KRT26 and TCHH genes and analyzed the effect of SNPs on production performance by SPSS software. Two SNPs sites (A559T and A6839G) of two genes were detected. The AA genotype of KRT26 A559T locus was the dominant genotype. AG and GG at TCHH A6839G locus were the dominant genotypes. AAAA was the dominant haplotype combination. The results showed that KRT26 and TCHH genes were associated with cashmere fineness of LCG, and A559T (AA) and A6839G (GG) genotypes were the preferred marker genotypes for cashmere fineness, which provided more theoretical basis for further research on cashmere fineness.

During evolution from the earliest tetrapoda, newly-recruited genes are increasingly paralogues of existing genes and distribute non-randomly among the chromosomes

BACKGROUND

The present availability of full genome sequences of a broad range of animal species across the whole range of evolutionary history enables one to ask questions as to the distribution of genes across the chromosomes. Do newly recruited genes, as new clades emerge, distribute at random or at non-random locations?

RESULTS

We extracted values for the ages of the human genes and for their current chromosome locations, from published sources. A quantitative analysis showed that the distribution of newly-added genes among and within the chromosomes appears to be increasingly non-random if one observes animals along the evolutionary series from the precursors of the tetrapoda through to the great apes, whereas the oldest genes are randomly distributed.

CONCLUSIONS

Randomization will result from chromosome evolution, but less and less time is available for this process as evolution proceeds. Much of the bunching of recently-added genes arises from new gene formation as paralogues in gene families, near the location of genes that were recruited in the preceding phylostratum. As examples we cite the KRTAP, ZNF, OR and some minor gene families. We show that bunching can also result from the evolution of the chromosomes themselves when, as for the KRTAP genes, blocks of genes that had previously been on disparate chromosomes become linked together.

Integrative Analyses of Genes Associated with Hashimoto's Thyroiditis

OBJECTIVE

Hashimoto's thyroiditis, also known as chronic lymphocytic thyroiditis, is a common autoimmune thyroiditis, which mostly occurs in young and middle-aged women. It can be manifested as hyperthyroidism in the early stage; hypothyroidism may appear with the progression of the disease. Studies have shown that multiple factors such as heredity, environment, and autoimmunity are involved in the pathogenesis, but the specific mechanism is not clear. In our study, we tried to find key genes and potential molecular mechanisms of Hashimoto's thyroiditis to provide new ideas for the therapeutic targets of Hashimoto's thyroiditis.

METHOD

GSE138198 and GSE54958 were downloaded from the GEO database, and two datasets were combined for analysis. The combined data were normalized to identify the differentially expressed genes (DEGs), and GO and KEGG enrichment analyses were performed. Protein-protein interaction (PPI) networks and hub genes between DEGs were identified. We also used the miRWalk database to identify regulatory miRNAs associated with expressions of DEGs.

RESULT

We identified 182 DEGs (160 upregulated and 22 downregulated) between Hashimoto's disease patients and the healthy control group. GO analysis showed that DEGs were mostly concentrated in detection of chemical stimulus involved in sensory perception, intermediate filament cytoskeleton, and olfactory receptor activity. KEGG pathway analysis showed that DEGs were mainly related to olfactory transduction. Some members of the KRTAP family and HTR5A, KNG1, DRD3, HTR1D, TAS2R16, INSL5, TAS2R42, and GRM7 are the most important hub genes in the PPI network. In addition, we recognized that OTUD4, LLPH, and ECHDC1 were the most important hub genes in the miRNA-target gene network.

CONCLUSION

In this study, a series of bioinformatics analyses of DEGs were performed to identify the key genes and pathways associated with Hashimoto's thyroiditis. These genes and pathways provide a more detailed understanding of the pathogenesis of Hashimoto's disease and provide new ideas for the therapeutic targets of Hashimoto's thyroiditis.

Immunolocalization and phylogenetic profiling of the feather protein with the highest cysteine content

Feathers are the most complex skin appendages of vertebrates. Mature feathers consist of interconnected dead keratinocytes that are filled with heavily cross-linked proteins. Although the molecular architecture determines essential functions of feathers, only few feather proteins have been characterized with regard to their amino acid sequences and evolution. Here, we identify Epidermal Differentiation protein containing DPCC Motifs (EDDM) as a cysteine-rich protein that has co-evolved with other feather proteins. The EDDM gene is located within the avian epidermal differentiation complex (EDC), a cluster of genes that has originated and diversified in amniotes. EDDM shares the exon-intron organization with EDC genes of other amniotes, including humans, and a gene encoding an EDDM-like protein is present in crocodilians, suggesting that avian EDDM arose by sequence modification of an epidermal differentiation gene present in a common ancestor of archosaurs. The EDDM protein contains multiple sequence repeats and a higher number of cysteine residues than any other protein encoded in the EDC. Immunohistochemical analysis of chicken skin and skin appendages showed expression of EDDM in barb and barbules of feathers as well as in the subperiderm on embryonic scutate scales. These results suggest that the diversification and differential expression of EDDM, besides other EDC genes, was instrumental in facilitating the evolution of the most complex molecular architecture of feathers.