PI3K/AKT/mTOR signaling pathway: an important driver and therapeutic target in triple-negative breast cancer.

Triple-negative breast cancer (TNBC) is a highly heterogeneous tumor lacking estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expression. It has higher aggressiveness and metastasis than other subtypes, with limited effective therapeutic strategies, leading to a poor prognosis. The phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mechanistic target of rapamycin (mTOR) signaling pathway is prevalently over-activated in human cancers and contributes to breast cancer (BC) growth, survival, proliferation, and angiogenesis, which could be an interesting therapeutic target. This review summarizes the PI3K/AKT/mTOR signaling pathway activation mechanism in TNBC and discusses the relationship between its activation and various TNBC subtypes. We also report the latest clinical studies on kinase inhibitors related to this pathway for treating TNBC. Our review discusses the issues that need to be addressed in the clinical application of these inhibitors.

SAS: Split antibiotic selection for identifying chaperones that improve protein solubility.

Background: Heterologous expression of active, native-folded protein in Escherichia coli is critical in both academic research and biotechnology settings. When expressing non-native recombinant proteins in E. coli, obtaining soluble and active protein can be challenging. Numerous techniques can be used to enhance a proteins solubility, and largely focus on either altering the expression strain, plasmid vector features, growth conditions, or the protein coding sequence itself. However, there is no one-size-fits-all approach for addressing issues with protein solubility, and it can be both time and labor intensive to find a solution. An alternative approach is to use the co-expression of chaperones to assist with increasing protein solubility. By designing a genetic system where protein solubility is linked to viability, the appropriate protein folding factor can be selected for any given protein of interest. To this end, we developed a Split Antibiotic Selection (SAS) whereby an insoluble protein is inserted in-frame within the coding sequence of the hygromycin B resistance protein, aminoglycoside 7″-phosphotransferase-Ia (APH(7″)), to generate a tripartite fusion. By creating this tripartite fusion with APH(7″), the solubility of the inserted protein can be assessed by measuring the level of hygromycin B resistance of the cells. Results: We demonstrate the functionality of this system using a known protein and co-chaperone pair, the human mitochondrial Hsp70 ATPase domain (ATPase70) and its co-chaperone human escort protein (Hep). Insertion of the insoluble ATPase70 within APH(7'') renders the tripartite fusion insoluble and results in sensitivity to hygromycin B. Antibiotic resistance can be rescued by expression of the co-chaperone Hep which assists in the folding of the APH(7'')-ATPase70-APH(7'') tripartite fusion and find that cellular hygromycin B resistance correlates with the total soluble fusion protein. Finally, using a diverse chaperone library, we find that SAS can be used in a pooled genetic selection to identify chaperones capable of improving client protein solubility. Conclusions: The tripartite APH(7'') fusion links the in vivo solubility of the inserted protein of interest to hygromycin B resistance. This construct can be used in conjunction with a chaperone library to select for chaperones that increase the solubility of the inserted protein. This selection system can be applied to a variety of client proteins and eliminates the need to individually test chaperone-protein pairs to identify those that increase solubility.

Prognosis prediction and risk stratification of breast cancer patients based on a mitochondria-related gene signature.

As the malignancy with the highest global incidence, breast cancer represents a significant threat to women's health. Recent advances have shed light on the importance of mitochondrial function in cancer, particularly in metabolic reprogramming within tumors. Recognizing this, we developed a novel risk signature based on mitochondrial-related genes to improve prognosis prediction and risk stratification in breast cancer patients. In this study, transcriptome data and clinical features of breast cancer samples were extracted from two sources: the TCGA, serving as the training set, and the METABRIC, used as the independent validation set. We developed the signature using LASSO-Cox regression and assessed its prognostic efficacy via ROC curves. Furthermore, the signature was integrated with clinical features to create a Nomogram model, whose accuracy was validated through clinical calibration curves and decision curve analysis. To further elucidate prognostic variations between high and low-risk groups, we conducted functional enrichment and immune infiltration analyses. Additionally, the study encompassed a comparison of mutation landscapes and drug sensitivity, providing a comprehensive understanding of the differing characteristics in these groups. Conclusively, we established a risk signature comprising 8 mitochondrial-related genes-ACSL1, ALDH2, MTHFD2, MRPL13, TP53AIP1, SLC1A1, ME3, and BCL2A1. This signature was identified as an independent risk predictor for breast cancer patient survival, exhibiting a significant high hazard ratio (HR = 3.028, 95%CI 2.038-4.499, P < 0.001). Patients in the low-risk group showed a more favorable prognosis, with enhanced immune infiltration, distinct mutation landscapes, and greater sensitivity to anti-tumor drugs. In contrast, the high-risk group exhibited an adverse trend in these aspects. This risk signature represents a novel and effective prognostic indicator, suggesting valuable insights for patient stratification in breast cancer.

A flavin-monooxygenase catalyzing oxepinone formation and the complete biosynthesis of vibralactone.

Oxepinone rings represent one of structurally unusual motifs of natural products and the biosynthesis of oxepinones is not fully understood. 1,5-Seco-vibralactone (3) features an oxepinone motif and is a stable metabolite isolated from mycelial cultures of the mushroom Boreostereum vibrans. Cyclization of 3 forms vibralactone (1) whose ß-lactone-fused bicyclic core originates from 4-hydroxybenzoate, yet it remains elusive how 4-hydroxybenzoate is converted to 3 especially for the oxepinone ring construction in the biosynthesis of 1. In this work, using activity-guided fractionation together with proteomic analyses, we identify an NADPH/FAD-dependent monooxygenase VibO as the key enzyme performing a crucial ring-expansive oxygenation on the phenol ring to generate the oxepin-2-one structure of 3. The crystal structure of VibO reveals that it forms a dimeric phenol hydroxylase-like architecture featured with a unique substrate-binding pocket adjacent to the bound FAD. Computational modeling and solution studies provide insight into the likely VibO active site geometry, and suggest possible involvement of a flavin-C4a-OO(H) intermediate.

An updated analysis on the association of GSTM1 polymorphism and smoking exposure with the increased risk of coronary heart disease.

OBJECTIVE: To undertake a meta-analysis to investigate if there is an association between the glutathione S-transferase mu 1 (GSTM1) gene polymorphism, coronary artery disease (CAD) susceptibility and smoking. METHODS: Electronic databases, including PubMed®, Web of Science and Embase®, were searched for relevant case-control studies. Data were extracted and the odds ratio (OR) was calculated and appropriate statistical methods were used for the meta-analysis. RESULTS: The analysis included eight studies with a total of 1880 cases with CAD and 1758 control subjects. The results of this meta-analysis demonstrated that there is no association between the GSTM1 null and CAD (OR 1.24, 95% confidence interval [CI] 1.00, 1.55). An increased risk of CAD was observed in the smoking population with the GSTM1 null genotype (OR 1.48, 95% CI 1.02, 2.15). Subgroup analyses of geographical region, genotyping method and publication language category demonstrated potential relationships among gene polymorphism, smoking and CAD. CONCLUSIONS: Based on the current literature, the GSTM1 null genotype was associated to CAD in the smoking population. The interaction between smoking and GSTM1 polymorphism may contribute to the susceptibility of CAD.

Risk factors for asthma in patients with allergic rhinitis in eastern China.

BACKGROUND: Asthma is one of the most common chronic diseases among children and adults and can lead to a high health and socioeconomic burden. Allergic rhinitis (AR) often precedes the development of asthma. This study aims to clarify the risk factors for cocurrent asthma in patients with AR in eastern China. METHODS: A cross-sectional study of 3739 patients with AR was performed in eastern China. Patients meeting the criteria for AR were evaluated using a skin-prick test (SPT) of 16 common aeroallergens. A logistic regression analysis was used to assess the risk factors of asthma in patients with AR. RESULTS: The prevalence of asthma in patients with AR was 14.23%. The patients sensitive to dust mites (D. farinae and D. pteronyssinus) had the highest prevalence (76.84% and 73.68%). A significant difference was found in sensitization to four types of allergens (D. farinae, D. pteronyssinus, dog dander, Alternaria alternata) in patients with AR with and without asthma. The strongest risk factor for asthma in patients with AR was an allergy to Aspergillus fumigatus (adjusted OR, 2.42; 95% CI, 1.50-3.90), followed by allergy to D. pteronyssinus (adjusted OR, 2.06; 1.30-3.27), and allergy to dog dander (adjusted OR, 1.92; 1.24-2.97). Various risk factors that are independently associated with asthma in patients with AR were found in different age groups. CONCLUSIONS: We observed a difference in risk factors in patients with AR with and without asthma. Clarifying the risk factors for asthma in patients with AR is important and may be beneficial to the optimal interventions of asthma.

IL-21 Enhances the Immune Protection Induced by the Vibrio vulnificus Hemolysin A Protein.

We previously reported that the Vibrio vulnificus hemolysin A (VvhA) protein elicited good immune protection and could effectively control V. vulnificus infection in mice. However, its molecular mechanism remains unknown. We hypothesized that hemolysin A induces an immunoprotective response via IL-21 regulation. To demonstrate this, IL-21 expression in mice was regulated by injecting either specific antibodies or rIL-21, and the immune response was evaluated by flow cytometry. Our results suggested that IL-21 enhances immune protection by inducing a T follicular helper cell and germinal center B cell response. We used RNA-seq to explore molecular mechanisms and identified 10 upregulated and 32 downregulated genes involved in IL-21-upregulated protection. Gene Ontology analysis and pathway analysis of the differentially expressed genes were also performed. Our findings indicate that IL-21 can enhance the immune protection effect of the VvhA protein and may serve as a novel strategy for enhancing the immune protection effect of protein vaccines.

MicroRNA-432 inhibits milk fat synthesis by targeting SCD and LPL in ovine mammary epithelial cells.

The microRNA (miR)-432 is differentially expressed in the mammary gland of two breeds of lactating sheep with different milk production traits, and between the non-lactating and peak-lactation periods, but there have been no reports describing the molecular mechanisms involved. In this study, the effect of miR-432 on the proliferation of ovine mammary epithelial cells (OMECs) and the target genes of miR-432 were investigated. The effects of miR-432 on the expression of the target genes and the content of triglycerides in the OMECs were also analyzed. Transfection with a miR-432 mimic was found using CCK8 and Edu assays, to inhibit the viability of OMECs and reduce the number of proliferated OMECs. In contrast, a miR-432 inhibitor had the opposite effect to the miR-432 mimic, and together these results suggest that miR-432 inhibits the proliferation of OMECs. A dual luciferase assay revealed that the genes for stearoyl-CoA desaturase (SCD) and lipoprotein lipase (LPL) are targeted by miR-432. The transfection of miR-432 mimic into OMECs resulted in decreases in the expression of SCD and LPL, and three other milk fat synthesis marker genes; FABP4, LPIN1 and ACACA. The mimic also decreased the content of triglycerides. The miR-432 inhibitor had the opposite effect to the mimic on the expression of these genes and the level of triglycerides. This is the first study to reveal the biological mechanisms by which miR-432 inhibits milk fat synthesis in sheep.

An Efficient Nomogram to Predict Overall Survival of Patients with Pediatric Ewing's Sarcoma: A Population-Based Study.

BACKGROUND: The objective of our study was to develop and validate a nomogram to predict the overall survival (OS) of patients with pediatric Ewing's sarcoma (PES). METHODS: Age, gender, race, tumor stage, tumor size, tumor site, treatment method, and survival time were collected from patients diagnosed with PES between 2004 and 2016 from the Surveillance, Epidemiology, and End Results (SEER) database. A total of 772 patients were randomly allocated to a training dataset (n = 579) and a validation dataset (n = 193). Then, univariate and multivariate analyses were performed to determine the prognostic effect of the selected variables. A nomogram was constructed to estimate the OS and it was further assessed using the concordance index (C-index), calibration curves, and receiver operating characteristic (ROC). RESULTS: Age, race, tumor size, and tumor stage were included in the nomogram. The C-index was 0.77 in the OS for the training dataset. The C-index for the validation dataset of the OS prediction was 0.75. Calibration plots and ROC curves showed excellent predictive accuracy. CONCLUSION: Age, race, tumor stage, and tumor size were independent prognostic factors for patients with PES. The nomogram showed an accurate and reliable prognostic performance for PES patients.

A useful epitope tag derived from maltose binding protein.

Maltose binding protein (MBP) is used in recombinant protein expression as an affinity and solubility tag. The monoclonal antibody B48 binds MBP tightly and has no cross-reactivity to other proteins in an Escherichia coli lysate. This high level of specificity suggested that MBP contains an epitope that could prove useful as a purification and visualization tag for proteins expressed in E. coli. To discover the MBP epitope, a co-crystal structure was determined for MBP bound to its antibody and four amino acids of MBP were identified as critical for the binding interaction. Fusions of various fragments of MBP to the glutathione S-transferase protein were engineered in order to identify the smallest fragment still recognized by the α-MBP antibody. Stabilization of the epitope via mutational engineering resulted in a minimized 14 amino-acid tag.

MicroRNA-148a Regulates the Proliferation and Differentiation of Ovine Preadipocytes by Targeting PTEN.

MicroRNAs (miRNAs) have been found to be involved in lipid deposition and metabolism. However, there have been no reports on the roles of miR-148a in the proliferation and adipogenesis of preadipocytes in sheep. In this study, the expression of miR-148a was profiled in the eight tissues of Tibetan ewes and differentiated preadipocytes, and the role of miR-148a in differentiation and proliferation of ovine preadipocytes was investigated using Oil Red O staining, CCK-8, EdU staining, cell cycle detection, and RT-qPCR. The effect of PTEN on the differentiation of ovine preadipocytes was also investigated. The miR-148a was widely expressed in the eight tissues investigated and had significantly increased expression in liver, spleen and subcutaneous adipose tissues, and the heart. The expression of miR-148a continued to increase with the differentiation of ovine preadipocytes. The over-expression of miR-148a significantly promoted differentiation but inhibited the proliferation of ovine preadipocytes. The inhibition of miR-148a had the opposite effect on the differentiation and proliferation of ovine preadipocytes with over-expressed miR-148a. The results from the dual luciferase reporter assays showed that miR-148a mimic significantly decreased the luciferase activity of PTEN-3'UTR dual luciferase reporter vector, suggesting that PTEN is a target gene of miR-148a. In over-expressed-PTEN preadipocytes, the number of lipid droplets remarkably decreased, and the expression levels of adipogenesis marker genes PPARγ, FASN, FATP4, GLUT4, C/EBPß and LPL were also significantly down-regulated. These results suggest that miR-148a accelerated the adipogenic differentiation of ovine preadipocytes by inhibiting PTEN expression, and also inhibited the proliferation of ovine preadipocytes.

Small RNA deep sequencing reveals the expressions of microRNAs in ovine mammary gland development at peak-lactation and during the non-lactating period.

MicroRNAs (miRNAs) are small non-coding RNAs that are involved in mammary gland development and lactation in livestock. Little is known about the roles of miRNAs in ovine mammary gland development, hence in this study the expression profiles of miRNAs of the mammary gland tissues of ewes at peak-lactation and during the non-lactating period were investigated using RNA sequencing. A total of 147 mature miRNAs were expressed in the two periods. Compared with peak-lactation, eight miRNAs in the non-lactating ewe mammary gland were significantly up-regulated, whereas fifteen miRNAs were down-regulated. A KEGG analysis revealed that the target genes of the up-regulated miRNAs were significantly enriched in lysosome, Wnt and MAPK signaling pathways, while the target genes of down-regulated miRNAs were significantly enriched in the PI3K-Akt signaling pathway, protein processing in endoplasmic reticulum and axon guidance. These results suggest that further study of the differentially expressed miRNAs could provide a better understanding of the molecular mechanisms of mammary development and lactation in sheep.

Identification and characterization of circular RNAs in mammary gland tissue from sheep at peak lactation and during the nonlactating period.

Circular RNAs are a class of noncoding RNA with a widespread occurrence in eukaryote tissues, and with some having been demonstrated to have clear biological function. In sheep, little is known about the role of circular RNAs in mammary gland tissue, and therefore an RNA sequencing approach was used to compare mammary gland tissue expression of circular RNAs in 9 Small Tail Han sheep at peak lactation, and subsequently when they were not lactating. These 9 sheep had their RNA pooled for analysis into 3 libraries from peak lactation and 3 from the nonlactating period. A total of 3,278 and 1,756 circular RNAs were identified in the peak lactation and nonlactating mammary gland tissues, respectively, and the expression and identity of 9 of them was confirmed using reverse transcriptase-polymerase chain reaction analysis and DNA sequencing. The type, chromosomal location and length of the circular RNAs identified were ascertained. Forty upregulated and one downregulated circular RNAs were characterized in the mammary gland tissue at peak lactation compared with the nonlactating mammary gland tissue. Gene ontology enrichment analysis revealed that the parental genes of these differentially expressed circular RNAs were related to molecular function, binding, protein binding, ATP binding, and ion binding. Five differentially expression circular RNAs were selected for further analysis to predict their target microRNAs, and some microRNAs reportedly associated with the development of the mammary gland were found in the constructed circular RNA-microRNA network. This study reveals the expression profiles and characterization of circular RNAs at 2 key stages of mammary gland activity, thereby providing an improved understanding of the roles of circular RNAs in the mammary gland of sheep.

Improved production of Humira antibody in the genetically engineered Escherichia coli SHuffle, by co-expression of human PDI-GPx7 fusions.

Microbial production of antibodies offers the promise of cheap, fast, and efficient production of antibodies at an industrial scale. Limiting this capacity in prokaryotes is the absence of the post-translational machinery, present in dedicated antibody producing eukaryotic cell lines, such as B cells. There has been few and limited success in producing full-length, correctly folded, and assembled IgG in the cytoplasm of prokaryotic cell lines. One such success was achieved by utilizing the genetically engineered Escherichia coli strain SHuffle with an oxidative cytoplasm. Due to the genetic disruption of reductive pathways, SHuffle cells are under constant oxidative stress, including increased levels of hydrogen peroxide (H2O2). The oxidizing capacity of H2O2 was linked to improved disulfide bond formation, by expressing a fusion of two endoplasmic reticulum-resident proteins, the thiol peroxidase GPx7 and the protein disulfide isomerase, PDI. In concert, these proteins mediate disulfide transfer from H2O2 to target proteins via PDI-Gpx7 fusions. The potential of this new strain was tested with Humira, a blockbuster antibody usually produced in eukaryotic cells. Expression results demonstrate that the new engineered SHuffle strain (SHuffle2) could produce Humira IgG four-fold better than the parental strain, both in shake-flask and in high-density fermentation. These preliminary studies guide the field in genetically engineering eukaryotic redox pathways in prokaryotes for the production of complex macromolecules. KEY POINTS: • A eukaryotic redox pathway was engineered into the E. coli strain SHuffle in order to improve the yield of the blockbuster antibody Humira. • The best peroxidase-PDI fusion was selected using bioinformatics and in vivo studies. • Improved yields of Humira were demonstrated at shake-flask and high-density fermenters.

A Nomogram Predicting Overall and Cancer-Specific Survival of Patients with Primary Bone Lymphoma: A Large Population-Based Study.

We aimed to develop a nomogram for evaluating the overall survival (OS) and cancer-specific survival (CSS) in patients with primary bone lymphoma (PBL). Patients diagnosed with PBL between 2007 and 2016 were collected from the Surveillance, Epidemiology, and End Results (SEER) database. All patients were randomly allocated to the training cohort and validation cohort (2 : 1). The nomogram was developed by the training cohort and validated by the validation cohort using the concordance index (C-index), calibration plots, and decision curve analyses (DCAs). The C-index for CSS and OS prediction in the training cohort were 0.76 and 0.77, respectively; in the validation cohort, they were 0.76 and 0.79, respectively. The calibration curve showed good consistency between nomogram prediction and actual survival. The DCA indicated obvious net benefits of the new predictive model. The nomogram showed favorable applicability and accuracy, and it will be a reliable tool for predicting OS and CSS in patients with PBL.

RNA-Seq Reveals the Expression Profiles of Long Non-Coding RNAs in Lactating Mammary Gland from Two Sheep Breeds with Divergent Milk Phenotype.

Long non-coding RNAs (lncRNAs) are a kind of non-coding RNA with >200 nucleotides in length. Some lncRNAs have been proven to have clear regulatory functions in many biological processes of mammals. However, there have been no reports on the roles of lncRNAs in ovine mammary gland tissues. In the study, the expression profiles of lncRNAs were studied using RNA-Seq in mammary gland tissues from lactating Small-Tailed Han (STH) ewes and Gansu Alpine Merino (GAM) ewes with different milk yield and ingredients. A total of 1894 lncRNAs were found to be expressed. Compared with the GAM ewes, the expression levels of 31 lncRNAs were significantly up-regulated in the mammary gland tissues of STH ewes, while 37 lncRNAs were remarkably down-regulated. Gene Ontogeny (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis found that the target genes of differentially expressed lncRNAs were enriched in the development and proliferation of mammary epithelial cells, morphogenesis of mammary gland, ErbB signaling pathway, and Wnt signaling pathway. Some miRNA sponges of differentially expressed lncRNAs, reported to be associated with lactation and mammary gland morphogenesis, were found in a lncRNA-miRNA network. This study reveals comprehensive lncRNAs expression profiles in ovine mammary gland tissues, thereby providing a further understanding of the functions of lncRNAs in the lactation and mammary gland development of sheep.

Significantly reducing post-tonsillectomy hemorrhage requiring surgery by double-layer suture: A retrospective analysis.

BACKGROUND: Although tonsillectomies carry a low-risk for adverse events, postoperative hemorrhage has been reported as the most common complication. AIM: To compare the rates of postoperative secondary hemorrhage for tonsillectomy with or without double-layer suture. MATERIAL AND METHODS: This is a retrospective study of 5087 patients who underwent coblation tonsillectomy with or without suture from 2006 to 2016. All cases had been followed up 3 weeks and severe secondary hemorrhage cases requiring operation were analyzed. RESULTS: The severe secondary hemorrhage rate was statistically higher in group without suture (1.96%) as compared with the group with suture (1.08%). The surgery time (36.55 ± 7.45) was longer in patients with suture as compared to patients without suture (31.50 ± 6.23). In the age between 18 and 49 years group, the higher secondary hemorrhage rate (2.44%) was found in patients without suture. The rate of postoperative hemorrhage (0.96%) was significantly higher in patients without suture as compared with patients with suture (0.36%) on postoperative 5th day. CONCLUSIONS: The risk of severe secondary hemorrhage is reduced in coblation tonsillectomy with suture. The rate of secondary hemorrhage is lower in patients with suture in 18 to 49 years old group and on the 5th day after surgery.

[Downregulation of SND1 Expression Accelerates Cell Senescence of Human Diploid Fibroblasts 2BS via Modulating the SASP].

OBJECTIVE: To investigate the effect of down-regulation of SND1 expression on senescence of human diploid fibroblasts. METHODS: Western blot and immunohistochemistry were used to detect the expression of SND1 in young or senescent 2BS cells and aged tissues. Immunofluorescence was conducted to detect the localization of SND1 in young 2BS cells. CCK8 and EDU were performed to detect the proliferation of 2BS. Colony formation analysis was used to evaluate the capacity of colony formation of 2BS. Expression chip and RT-qPCR analysis were performed to detect the change of SASP expression level. ß-galactosidase staining was employed to indicate the senescent 2BS cells. RESULTS: The expression of SND1 in the senescent 2BS cells was significantly down-regulated compared with in the younger 2BS cells, and in human colon adenomas, its expression was also significantly down-regulated compared with in non-lesion colon tissues. In young 2BS, knockdown of SND1 inhibited the proliferation and colony formation of 2BS, and led to stronger senescence-associated beta-galactosidase staining (SA-ß-gal). Expression chip and RT-qPCR analysis indicated that knockdown of SND1 up-regulated the expression of senescence-associated secretory phenotype components (SASP). CONCLUSIONS: Our data indicated that down-regulation of SND1 regulated human diploid cell senescence by up-regulating the expression of SASP components.

Identification of the Ovine Keratin-Associated Protein 2-1 Gene and Its Sequence Variation in Four Chinese Sheep Breeds.

Keratin-associated proteins are important components of wool fibers. The gene encoding the high-sulfur keratin-associated protein 2-1 has been described in humans, but it has not been described in sheep. A basic local alignment search tool nucleotide search of the Ovine Genome Assembly version 4.0 using a human keratin-associated protein 2-1 gene sequence revealed a 399-base pair open reading frame, which was clustered among nine previously identified keratin-associated protein genes on chromosome 11. Polymerase chain reaction-single strand conformation polymorphism analysis revealed four different banding patterns, with these representing four different sequences (A-D) in Chinese sheep breeds. These sequences had the highest similarity to human keratin-associated protein 2-1 gene, suggesting that they represent variants of ovine keratin-associated protein 2-1 gene. Nine single nucleotide variations were detected in the gene, including one non-synonymous nucleotide substitution. Differences in variant frequencies between fine-wool sheep breeds and coarse-wool sheep breeds were detected. The gene was found to be expressed in various tissues, with the highest expression level in skin, and moderate expression levels in heart and lung tissue. These results reveal that the ovine keratin-associated protein 2-1 gene is variable and suggest the gene might affect variation in mean fiber diameter.