The human transketolase-like proteins TKTL1 and TKTL2 are bona fide transketolases

Exploring the impact of age, and body condition score on erythrocytic B1-Dependent transketolase activity in cats: A comprehensive analysis of thiamine status

One of the key factors influencing aging and morbidity is the overall antioxidant status and regenerative capacity. In examining contributors to the antioxidant status, we analyzed the thiamine status in felines and the influence of age, gender, and body condition score. We measured erythrocytic B1-dependent specific transketolase (STKT) activity, an enzyme in the pentose phosphate pathway, in a group of 60 sexually intact, healthy, and specific pathogen-free felines (44 females, 16 males, aged 1-17 years) with thiamine diphosphate (TDP; 0.3 and 3 mM) and without it. Only two parameters (STKT activity with and without 0.3 mM TDP) decreased with age. After adjusting for age, statistical thresholds were established using these and other age-independent parameters, identifying 15 felines with subclinical thiamine deficiency. The red blood cell proteomics analysis revealed that the pentose phosphate shunt, glycolysis, and oxidative stress response were the most affected pathways in deficient felines, confirming the above diagnosis. Age emerged as the primary factor associated with thiamine deficiency, supported by the enrichment of neurodegenerative diseases with a proteotoxicity component; five young-adult felines showed marginal or acute B1 deficiency, and six were adult-mature with a more chronic deficiency, possibly linked to cognitive decline, all with an underweight to ideal body condition scores. Only three senior-adult felines were deficient and overweight-obese. Detecting thiamine deficiency emphasizes the need for more accurate reference values, the establishment of advanced preventive or therapeutic measures to enhance the well-being of aging companion animals, and potential extensions to human health, particularly concerning cognitive function.

Stage-specific regulation of undifferentiated spermatogonia by AKT1S1-mediated AKT-mTORC1 signaling during mouse spermatogenesis

Undifferentiated spermatogonia are composed of a heterogeneous cell population including spermatogonial stem cells (SSCs). Molecular mechanisms underlying the regulation of various spermatogonial cohorts during their self-renewal and differentiation are largely unclear. Here we show that AKT1S1, an AKT substrate and inhibitor of mTORC1, regulates the homeostasis of undifferentiated spermatogonia. Although deletion of Akt1s1 in mouse appears not grossly affecting steady-state spermatogenesis and male mice are fertile, the subset of differentiation-primed OCT4+ spermatogonia decreased significantly, whereas self-renewing GFRα1+ and proliferating PLZF+ spermatogonia were sustained. Both neonatal prospermatogonia and the first wave spermatogenesis were greatly reduced in Akt1s1-/- mice. Further analyses suggest that OCT4+ spermatogonia in Akt1s1-/- mice possess altered PI3K/AKT-mTORC1 signaling, gene expression and carbohydrate metabolism, leading to their functionally compromised developmental potential. Collectively, these results revealed an important role of AKT1S1 in mediating the stage-specific signals that regulate the self-renewal and differentiation of spermatogonia during mouse spermatogenesis.

Whole-genome sequencing identifies new candidate genes for nonobstructive azoospermia

BACKGROUND

Genetic causes that lead to spermatogenetic failure in patients with nonobstructive azoospermia (NOA) have not been yet completely established.

OBJECTIVE

To identify low-frequency NOA-associated single nucleotide variants (SNVs) using whole-genome sequencing (WGS).

MATERIALS AND METHODS

Men with various types of NOA (n = 39), including samples that had been previously tested with whole-exome sequencing (WES; n = 6) and did not result in diagnostic conclusions. Variants were annotated using the Ensembl Variant Effect Predictor, utilizing frequencies from GnomAD and other databases to provide clinically relevant information (ClinVar), conservation scores (phyloP), and effect predictions (i.e., MutationTaster). Structural protein modeling was also performed.

RESULTS

Using WGS, we revealed potential NOA-associated SNVs, such as: TKTL1, IGSF1, ZFPM2, VCX3A (novel disease causing variants), ESX1, TEX13A, TEX14, DNAH1, FANCM, QRICH2, FSIP2, USP9Y, PMFBP1, MEI1, PIWIL1, WDR66, ZFX, KCND1, KIAA1210, DHRSX, ZMYM3, FAM47C, FANCB, FAM50B (genes previously known to be associated with infertility) and ALG13, BEND2, BRWD3, DDX53, TAF4, FAM47B, FAM9B, FAM9C, MAGEB6, MAP3K15, RBMXL3, SSX3 and FMR1NB genes, which may be involved in spermatogenesis.

DISCUSSION AND CONCLUSION

In this study, we identified novel potential candidate NOA-associated genes in 29 individuals out of 39 azoospermic males. Note that in 5 out of 6 patients subjected previously to WES analysis, which did not disclose potentially causative variants, the WGS analysis was successful with NOA-associated gene findings.

The role of transketolase in human cancer progression and therapy

Transketolase (TKT) is an enzyme that is ubiquitously expressed in all living organisms and has been identified as an important regulator of cancer. Recent studies have shown that the TKT family includes the TKT gene and two TKT-like (TKTL) genes; TKTL1 and TKTL2. TKT and TKTL1 have been reported to be involved in the regulation of multiple cancer-related events, such as cancer cell proliferation, metastasis, invasion, epithelial-mesenchymal transition, chemoradiotherapy resistance, and patient survival and prognosis. Therefore, TKT may be an ideal target for cancer treatment. More importantly, the levels of TKTL1 were detected using EDIM technology for the early detection of some malignancies, and TKTL1 was more sensitive and specific than traditional tumor markers. Detecting TKTL1 levels before and after surgery could be used to evaluate the surgery's effect. While targeted TKT suppresses cancer in multiple ways, in some cases, it has detrimental effects on the organism. In this review, we discuss the role of TKT in different tumors and the detailed mechanisms while evaluating its value and limitations in clinical applications. Therefore, this review provides a basis for the clinical application of targeted therapy for TKT in the future, and a strategy for subsequent cancer-related research.

The succinylome of Pinctada fucata martensii implicates lysine succinylation in the allograft-induced stress response

Lysine succinylation is a novel protein post-translational modification associated with the regulation of a variety of cellular processes. Post-translational modifications may regulate the immune response of Pinctada fucata martensii, a marine bivalve used to produce cultured pearls, in response to the surgical implantation of the seed pearl. This allograft-induced stress response may lead to transplant rejection or host death. However, the regulatory effects of post-translational modifications following nucleus insertion surgery in P.f. martensii remain largely unknown. Here, we used 4D label-free quantitative proteomics (4D-LFQ) with LC-MS/MS to explore the effects of nucleus implantation on lysine succinylation in P.f. martensii. We identified 4430 succinylated sites on 964 succinylated proteins in P.f. martensii after nucleus insertion surgery, and seven conserved motifs were identified upstream and downstream of these sites. In total, 269 succinylation sites were differentially expressed in response to implantation (|fold-change| > 1.5 and FDR <1%; 211 upregulation and 58 downregulation), corresponding to 163 differentially expressed succinylated proteins (DESPs; 124 upregulated and 39 downregulated). The terms over-enriched in the DESPs included "cellular processes", "metabolic pathways", and "binding activity", while the significantly enriched pathways included "ECM-receptor interaction", "PI3K-Akt signaling", and "focal adhesion". "EGF-like structural domains", "platelet-responsive protein type 1 structural domains", and "laminin EGF-like (domains III and V) domains" were overrepresented in the DESPs. Parallel reaction-monitoring (PRM) analysis validated 13 DESPs from the proteomics data. The succinylome of P.f. martensii (generated here for the first time) helps to clarify the biological role of large-scale succinylation in this bivalve after nucleus insertion surgery, providing a theoretical basis for further investigations of stress-induced post-translational modifications in other mollusks and extending our knowledge of the molluscan succinylated proteome.

Comparative proteomics analysis of human FFPE testicular tissues reveals new candidate biomarkers for distinction among azoospermia types and subtypes

Understanding molecular mechanisms that underpin azoospermia and discovery of biomarkers that could enable reliable, non-invasive diagnosis is highly needed. Using label-free data-independent LC-MS/MS acquisition coupled with ion mobility, we compared the FFPE testicular proteome of patients with obstructive (OA) and non-obstructive azoospermia (NOA) subtypes hypospermatogenesis (Hyp) and Sertoli cell-only syndrome (SCO). Out of 2044 proteins identified based on ≥2 peptides, 61 proteins had the power to quantitatively discriminate OA from NOA and 30 to quantitatively discriminate SCO from Hyp and OA. Among these, H1-6, RANBP1 and TKTL2 showed superior potential for quantitative discrimination among OA, Hyp and SCO. Integrin signaling pathway, adherens junction, planar cell polarity/convergent extension pathway and Dectin-1 mediated noncanonical NF-kB signaling were significantly associated with the proteins that could discriminate OA from NOA. Comparison with 2 transcriptome datasets revealed 278 and 55 co-differentially expressed proteins/genes with statistically significant positive correlation. Gene expression analysis by qPCR of 6 genes (H1-6, RANBP1, TKTL2, TKTL1, H2BC1, and ACTL7B) with the highest discriminatory power on protein level and the same regulation trend with transcriptomic datasets, confirmed proteomics results. In summary, our results suggest some underlying pathways in azoospermia and broaden the range of potential novel candidates for diagnosis. SIGNIFICANCE: Using a comparative proteomics approach on testicular tissue we have identified several pathways associated with azoospermia and a number of testis-specific and germ cell-specific proteins that have the potential to pinpoint the type of spermatogenesis failure. Furthermore, comparison with transcriptomics datasets based on genome-wide gene expression analyses of human testis specimens from azoospermia patients identified proteins that could discriminate between obstructive and non-obstructive azoospermia subtypes on both protein and mRNA levels. Up to our knowledge, this is the first integrated comparative analysis of proteomics and transcriptomics data from testicular tissues. We believe that the data from our study contributes significantly to increase the knowledge of molecular mechanisms of azoospermia and pave the way for new investigations in regards to non-invasive diagnosis.

Investigation of the effects of overexpression of jumping translocation breakpoint (JTB) protein in MCF7 cells for potential use as a biomarker in breast cancer

Jumping translocation breakpoint (JTB) gene acts as a tumor suppressor or an oncogene in different malignancies, including breast cancer (BC), where it was reported as overexpressed. However, the molecular functions, biological processes and underlying mechanisms through which JTB protein causes increased cell growth, proliferation and invasion is still not fully deciphered. Our goal is to identify the functions of JTB protein by cellular proteomics approaches. MCF7 breast cancer cells were transfected with sense orientation of hJTB cDNA in HA, His and FLAG tagged CMV expression vector to overexpress hJTB and the expression levels were confirmed by Western blotting (WB). Proteins extracted from transfected cells were separated by SDS-PAGE and the in-gel digested peptides were analyzed by nano-liquid chromatography tandem mass spectrometry (nanoLC-MS/MS). By comparing the proteome of cells with upregulated conditions of JTB vs control and identifying the protein dysregulation patterns, we aim to understand the function of this protein and its contribution to tumorigenesis. Gene Set Enrichment Analysis (GSEA) algorithm was performed to investigate the biological processes and pathways that are associated with the JTB protein upregulation. The results demonstrated four significantly enriched gene sets from the following significantly upregulated pathways: mitotic spindle assembly, estrogen response late, epithelial-to-mesenchymal transition (EMT) and estrogen response early. JTB protein itself is involved in mitotic spindle pathway by its role in cell division/cytokinesis, and within estrogen response early and late pathways, contributing to discrimination between luminal and mesenchymal breast cancer. Thus, the overexpressed JTB condition was significantly associated with an increased expression of ACTNs, FLNA, FLNB, EZR, MYOF, COL3A1, COL11A1, HSPA1A, HSP90A, WDR, EPPK1, FASN and FOXA1 proteins related to deregulation of cytoskeletal organization and biogenesis, mitotic spindle organization, ECM remodeling, cellular response to estrogen, proliferation, migration, metastasis, increased lipid biogenesis, endocrine therapy resistance, antiapoptosis and discrimination between different breast cancer subtypes. Other upregulated proteins for overexpressed JTB condition are involved in multiple cellular functions and pathways that become dysregulated, such as tumor microenvironment (TME) acidification, the transmembrane transport pathways, glycolytic flux, iron metabolism and oxidative stress, metabolic reprogramming, nucleocytosolic mRNA transport, transcriptional activation, chromatin remodeling, modulation of cell death pathways, stress responsive pathways, and cancer drug resistance. The downregulated proteins for overexpressed JTB condition are involved in adaptive communication between external and internal environment of cells and maintenance between pro-apoptotic and anti-apoptotic signaling pathways, vesicle trafficking and secretion, DNA lesions repair and suppression of genes involved in tumor progression, proteostasis, redox state regulation, biosynthesis of macromolecules, lipolytic pathway, carbohydrate metabolism, dysregulation of ubiquitin-mediated degradation system, cancer cell immune escape, cell-to-cell and cell-to-ECM interactions, and cytoskeletal behaviour. There were no significantly enriched downregulated pathways.

TKTL1 Knockdown Impairs Hypoxia-Induced Glucose-6-phosphate Dehydrogenase and Glyceraldehyde-3-phosphate Dehydrogenase Overexpression

Increased expression of transketolase (TKT) and its isoform transketolase-like-1 (TKTL1) has been related to the malignant leukemia phenotype through promoting an increase in the non-oxidative branch of the pentose phosphate pathway (PPP). Recently, it has also been described that TKTL1 can have a role in survival under hypoxic conditions and in the acquisition of radio resistance. However, TKTL1’s role in triggering metabolic reprogramming under hypoxia in leukemia cells has never been characterized. Using THP-1 AML cells, and by combining metabolomics and transcriptomics techniques, we characterized the impact of TKTL1 knockdown on the metabolic reprogramming triggered by hypoxia. Results demonstrated that TKTL1 knockdown results in a decrease in TKT, glucose-6-phosphate dehydrogenase (G6PD) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activities and impairs the hypoxia-induced overexpression of G6PD and GAPDH, all having significant impacts on the redox capacity of NADPH- and NADH-related cells. Moreover, TKTL1 knockdown impedes hypoxia-induced transcription of genes encoding key enzymes and transporters involved in glucose, PPP and amino acid metabolism, rendering cells unable to switch to enhanced glycolysis under hypoxia. Altogether, our results show that TKTL1 plays a key role in the metabolic adaptation to hypoxia in THP-1 AML cells through modulation of G6PD and GAPDH activities, both regulating glucose/glutamine consumption and the transcriptomic overexpression of key players of PPP, glucose and amino acids metabolism.

Protein markers of spermatogenesis and their potential use in the management of azoospermia

INTRODUCTION

Azoospermia, absence of sperm in the ejaculate is classified as obstructive (OA) and non-obstructive azoospermia (NOA). In OA, sperm are produced, but due to physical obstruction in the male reproductive tract, they are not released in the ejaculate. NOA, on the other hand, is defined as the absence of sperm in the ejaculate due to testicular dysfunction. In NOA, spermatogenesis is frequently preserved in specific sites, and proteomics studies have been employed in order to identify men with preserved spermatogenesis.

AREAS COVERED

Differential protein expression in patients with male infertility is an indicator of impaired spermatogenesis. Here, we reviewed proteins with a potential role as biomarkers of spermatogenesis that could help in the management of non-obstructive and obstructive azoospermia. The following keywords were used for bibliographic research: seminal plasma, proteomics, male infertility, nonobstructive, obstructive, azoospermia, oligospermia.

EXPERT OPINION

Biopsy is an invasive and potentially harmful technique for detecting spermatogenesis in men with OA and NOA. Seminal plasma proteins are highly promising as biomarkers for spermatogenesis. Current literature presents a number of potential candidate biomarkers for determining preserved spermatogenesis.

B Vitamins Supplementation Can Improve Cognitive Functions and May Relate to the Enhancement of Transketolase Activity in A Rat Model of Cognitive Impairment Associated with High-fat Diets

OBJECTIVE

To determine whether B vitamin treatment was sufficient to reduce cognitive impairment associated with high-fat diets in rats and to modulate transketolase (TK) expression and activity.

METHODS

To test this, we separated 50 rats into five groups that were either fed a standard chow diet (controls) or a high-fat diet (experimental groups H0, H1, H2, and H3). H0 group animals received no additional dietary supplementation, while H1 group animals were administered 100 mg/kg body weight (BW) thiamine, 100 mg/kg BW riboflavin, and 250 mg/kg BW niacin each day, and group H2 animals received daily doses of 100 mg/kg BW pyridoxine, 100 mg/kg BW cobalamin, and 5 mg/kg BW folate. Animals in the H3 group received the B vitamin regimens administered to both H1 and H2 each day.

RESULTS

Over time, group H0 exhibited greater increases in BW and fat mass relative to other groups. When spatial and memory capabilities in these animals were evaluated via conditioned taste aversion (CTA) and Morris Water Maze (MWM), we found B vitamin treatment was associated with significant improvements relative to untreated H0 controls. Similarly, B vitamin supplementation was associated with elevated TK expression in erythrocytes and hypothalamus of treated animals relative to those in H0 (P<0.05).

CONCLUSION

Together, these findings suggest B vitamin can modulate hypothalamic TK activity to reduce the severity of cognitive deficits in a rat model of obesity. As such, B vitamin supplementation may be a beneficial method for reducing cognitive dysfunction in clinical settings associated with high-fat diets.

Transcriptional regulation of seven cyadox-related genes mainly activated by PI3K and NF-кB signaling pathways in PK-15 cells

Cyadox, a new antibacterial agent as the quinoxaline-1, 4-dioxides, has a good antibacterial and growth-promoting effect, and has the advantages of lower toxicity, adequate safety and faster absorption. Seven differential expressed genes (DEGs) induced by cyadox were screened in swine liver tissues, including Insulin-like Growth Factor-1 (IGF-1), Epidermal Growth Factor (EGF), Poly ADP-ribose polymerase (PARP), the Defender Against Apoptotic Death 1 (DAD1), Complement Component 3 (C3), Transketolase (TK) and cyadox-related novel gene (CRNG). To elucidate the signal mechanism that cyadox altered these genes expression, the time-effect relationship and signaling pathways related to 7 DEGs induced by cyadox were determined in Porcine Kidney-15 (PK-15) cells by RT-qPCR and the application of various signal pathway inhibitors. The phosphorylation levels of signal factors in PK-15 cells were detected by Western blot. The analyses demonstrated that, the mRNA expressions of 7 DEGs were significantly enhanced by cyadox mainly through the phosphoinositide 3-kinase (PI3K) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-кB) signaling pathways in PK-15 cells. Furthermore, EGF might be the early response gene of cyadox to activate downstream signaling pathways and regulates the expression of other related genes or directly exerting biological effects. In brief, cyadox mainly regulates the expression of these 7 genes by PI3K and NF-кB signaling pathways to exert it's antibacterial and growth-promoting activity in PK-15 cells.