BACKGROUND: Renal osteodystrophy (ROD) is a skeletal pathology associated with chronic kidney disease-mineral and bone disorder (CKD-MBD) that is characterized by aberrant bone mineralization and remodeling. ROD increases the risk of fracture and mortality in CKD patients. The underlying mechanisms of ROD remain elusive, partially due to the absence of an appropriate animal model. To address this gap, we established a stable mouse model of ROD using an optimized adenine-enriched diet and conducted exploratory analyses through ribonucleic acid sequencing (RNA-seq). METHODS: Eight-week-old male C57BL/6J mice were randomly allocated into three groups: control group ( n = 5), adenine and high-phosphate (HP) diet group ( n = 20), and the optimized adenine-containing diet group ( n = 20) for 12 weeks. We assessed the skeletal characteristics of model mice through blood biochemistry, microcomputed tomography (micro-CT), and bone histomorphometry. RNA-seq was utilized to profile gene expression changes of ROD. We elucidated the functions of differentially expressed genes (DEGs) using gene ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, and gene set enrichment analysis (GSEA). DEGs were validated via quantitative real-time polymerase chain reaction (qRT-PCR). RESULTS: By the fifth week, adenine followed by an HP diet induced rapid weight loss and high mortality rates in the mouse group, precluding further model development. Mice with optimized adenine diet-induced ROD displayed significant abnormalities in serum creatinine and blood urea nitrogen levels, accompanied by pronounced hyperparathyroidism and hyperphosphatemia. The femur bone mineral density (BMD) of the model mice was lower than that of control mice, with substantial bone loss and cortical porosity. ROD mice exhibited substantial bone turnover with an increase in osteoblast and osteoclast markers. Transcriptomic profiling revealed 1907 genes with upregulated expression and 723 genes with downregulated expression in the femurs of ROD mice relative to those of control mice. Pathway analyses indicated significant enrichment of upregulated genes in the sphingolipid metabolism pathway. The significant upregulation of alkaline ceramidase 1 ( Acer1 ), alkaline ceramidase 2 ( Acer2 ), prosaposin-like 1 ( Psapl1 ), adenosine A1 receptor ( Adora1 ), and sphingosine-1-phosphate receptor 5 ( S1pr5 ) were successfully validated in mouse femurs by qRT-PCR. CONCLUSIONS Optimized adenine diet mouse model may be a valuable proxy for studying ROD. RNA-seq analysis revealed that the sphingolipid metabolism pathway is likely a key player in ROD pathogenesis, thereby providing new avenues for therapeutic intervention.
Animals ; Mice ; Chronic Kidney Disease-Mineral and Bone Disorder/genetics* ; Male ; Disease Models, Animal ; Mice, Inbred C57BL ; Sphingolipids/metabolism* ; Transcriptome/genetics* ; Signal Transduction/genetics* ; X-Ray Microtomography ; Adenine

OBJECTIVE: To study the clinical effects of ibrutinib in the treatment of relapsed/refractory diffuse large B-cell lymphoma (RRDLBCL). METHODS: A total of 101 patients with RRDLBCL in Daqing People's Hospital from September 2019 to September 2022 were selected. 45 patients were received ibrutinib monotherapy, 36 patients were received a combination therapy of ibrutinib, rituximab, and lenalidomide, and 20 patients were received a combination therapy of ibrutinib and lenalidomide. The clinical effects were observed. RESULTS: The median duration of treatment for all patients was 4 (2-9) months. The disease control rates(DCR) and objective response rates(ORR) in the ibrutinib monotherapy group were 46.67% and 26.67%, respectively. In the combination therapy group of ibrutinib, rituximab, and lenalidomide, the DCR and ORR were 69.44% and 44.44%, respectively. In the combination therapy group of ibrutinib and lenalidomide, the DCR and ORR were 60.00% and 35.00%, respectively. The DCR and ORR in the combination therapy group of ibrutinib, rituximab, and lenalidomide were significantly higher than those in the ibrutinib monotherapy group (P < 0.05). There were no significant differences in DCR and ORR between the combination therapy group of ibrutinib and lenalidomide and the ibrutinib monotherapy group (P >0.05). The median follow-up time of all patients was 15 (5-35) months, with a median overall survival(OS) of 21.0 (15.8-26.2) months and a median progression-free survival(PFS) of 14.0 (12.1-15.9) months. In the ibrutinib monotherapy group, the median OS and PFS were 15.0 (12.1-17.9) months and 12.0 (11.0-13.0) months, respectively. In the combination therapy group of ibrutinib and lenalidomide, the median OS and PFS were 22.0 (13.3-30.7) months and 16.0 (14.1-19.7) months, respectively. In the combination therapy group of ibrutinib, rituximab, and lenalidomide, the median OS and PFS were 23.0 (19.7-26.3) months and 17.0 (14.8-19.1) months, respectively. The median OS and PFS in the combination therapy group of ibrutinib, rituximab, and lenalidomide were significantly higher than those in the ibrutinib monotherapy group (P < 0.05). There were no significant differences in median OS and PFS between the combination therapy group of ibrutinib and lenalidomide and the combination therapy group of ibrutinib, rituximab, and lenalidomide (P >0.05). Hematological adverse reactions included neutropenia in 14 cases (13.86%), thrombocytopenia in 16 cases (15.84%), and leukopenia in 13 cases (12.87%). Non-hematological adverse reactions mainly included nausea and vomiting in 33 cases (32.67%) and fatigue in 44 cases (43.56%). CONCLUSION Ibrutinib has certain clinical effects and good safety in the treatment of RRDLBCL.
Humans ; Piperidines/therapeutic use* ; Lymphoma, Large B-Cell, Diffuse/drug therapy* ; Adenine/therapeutic use* ; Rituximab/therapeutic use* ; Lenalidomide/therapeutic use* ; Male ; Female ; Middle Aged ; Antineoplastic Combined Chemotherapy Protocols/therapeutic use* ; Adult ; Aged ; Pyrimidines/therapeutic use* ; Pyrazoles/therapeutic use* ; Treatment Outcome

OBJECTIVE: To investigate the impact of autophagy on cardiac tissue injury following common bile duct ligation (CBDL) in rats. METHODS: Twenty-four SPF grade healthy adult male Sprague-Dawley (SD) rats were randomly divided into four groups, with 6 rats in each group. The sham-operated (Sham) group underwent only dissection of the common bile duct without ligation. The CBDL group underwent CBDL to simulate jaundice-induced myocardial injury. The autophagy inhibitor 3-methyladenine (3-MA)+CBDL group was intraperitoneally injected with 15 mg/kg 3-MA 2 hours before modeling, and then injected once every other day. The CBDL+autophagy enhancer rapamycin (Rapa) group was intraperitoneally injected with Rapa 1 mg/kg 0.5 hour after modeling, and then injected once every other day. The rats in each group were sacrificed 2 weeks after surgery, and blood was taken from the inferior vena cava. Serum total bilirubin (TBil), alanine transaminase (ALT), aspartate transaminase (AST), lactate dehydrogenase (LDH), and MB isoenzyme of creatine kinase (CK-MB) were detected by using a fully automated animal biochemical analyzer. Serum oxidative stress marker superoxide dismutase (SOD) activity and malondialdehyde (MDA) content were detected by colorimetric assay. The heart tissues of rats were taken and pathological changes were observed under a light microscope after hematoxylin-eosin (HE) staining. Transmission electron microscope was used to observe autophagosomes after double staining with uranyl acetate and lead citrate. The expressions of autophagy-related proteins were detected using Western blotting. RESULTS: Compared with the Sham group, the serum SOD activity of rats in the CBDL group was significantly decreased, while the serum MDA, TBil, ALT, AST, LDH, and CK-MB were significantly increased; the expressions of autophagy-related proteins Beclin-1 and microtubule-associated protein 1 light chain 3-II/I (LC3-II/I) were significantly increased, and p62 protein expression was significantly decreased. Autophagosomes were seen under electron microscopy in the CBDL group, and cardiac histopathological morphology showed focal necrosis in the myocardium as well as infiltration of inflammatory cells, dilatation of small interstitial blood vessels, and myocardial fiber degeneration. Compared with the CBDL group, cardiac tissue injury in rats was attenuated by pretreatment with the autophagy inhibitor 3-MA, with a decrease in inflammatory cell infiltration in myocardial tissue, a reduction in interstitial vasodilatation, and a decrease in the area of myocardial fibrosis; a decrease in the number of autophagosomes by electron microscopy; and a further rise in the viability of serum TBil, ALT, and AST [TBil (μmol/L): 184.40±6.74 vs. 120.70±16.93, ALT (U/L): 501.10±62.18 vs. 178.80±22.30, AST (U/L): 806.50±76.92 vs. 275.50±55.81, all P < 0.01], as well as a decrease in the levels of serum SOD, MDA, LDH, and CK-MB [SOD (kU/L): 85.00±5.29 vs. 107.50±7.86, MDA (μmol/L): 10.72±0.93 vs. 15.06±1.88, LDH (U/L): 387.40±119.50 vs. 831.30±84.35, CK-MB (U/L): 320.10±14.04 vs. 814.70±75.66, all P < 0.05]. The expressions of the autophagy-related proteins Beclin-1 and LC3-II/I in cardiac tissues were significantly decreased [Beclin-1 protein (Beclin-1/GAPDH): 0.67±0.04 vs. 0.89±0.01, LC3-II/I ratio: 0.93±0.03 vs. 1.09±0.01, both P < 0.01], and p62 protein expression was significantly increased (p62/GAPDH: 0.99±0.01 vs. 0.60±0.01, P < 0.01). In contrast, compared with the CBDL group, after administration of the autophagy enhancer Rapa, the rats showed increased cardiac tissue injury, increased inflammatory cell infiltration in myocardial tissues, increased interstitial vasodilatation, and increased area of myocardial fibrosis; an increase in autophagosomes was seen by electron microscopy; the change tendency of serum biochemical indicators and proteins in myocardial tissues were opposite with autophagy inhibition group with a decrease in serum TBil, ALT, and AST [TBil (μmol/L): 22.00±3.21 vs. 120.70±16.93, ALT (U/L): 72.13±5.97 vs. 178.80±22.30, AST (U/L): 135.20±12.95 vs. 275.50±55.81, all P < 0.05], as well as a increase in the levels of serum SOD, MDA, LDH, and CK-MB [SOD (kU/L): 208.00±2.65 vs. 107.50±7.86, MDA (μmol/L): 20.38±0.40 vs. 15.06±1.88, LDH (U/L): 1 268.00±210.90 vs. 831.30±84.35, CK-MB (U/L): 1 150.00±158.70 vs. 814.70±75.66, all P < 0.05]. The protein expressions of Beclin-1 and LC3-II/I in cardiac tissues were significantly increased [Beclin-1 protein (Beclin-1/GAPDH): 0.96±0.01 vs. 0.89±0.01, LC3-II/I ratio: 1.19±0.01 vs. 1.09±0.01, both P < 0.05], and p62 protein expression was significantly decreased (p62/GAPDH: 0.19±0.02 vs. 0.60±0.01, P < 0.01). CONCLUSIONS Activation of autophagy in CBDL rats led to myocardial tissue injury and reduced cardiac function. Inhibition of autophagy improved cardiac tissue injury in CBDL rats, while increasing autophagy exacerbated myocardial tissue injury.
Animals ; Autophagy ; Rats, Sprague-Dawley ; Male ; Ligation ; Rats ; Common Bile Duct/surgery* ; Myocardium/pathology* ; Adenine/pharmacology*

OBJECTIVES: The mechanism of the odontogenic differentiation of apical papillary cells (APCs) stimulated by bioactive glass 45S5 is still unclear. This study aims to investigate the effect of autophagy on the odontogenic differentiation of APCs stimulated by bioactive glass 45S5. METHODS: APCs were isolated and cultured in vitro, and the cell origin was identified by flow cytometry. The culture medium was prepared with 1 mg/mL 45S5, and its pH and ion concentration were determined. The experiments were divided into control, 45S5, and 3-methyladenine (3-MA) 45S5 groups. In the 45S5 group, APCs were induced to culture with 1 mg/mL 45S5. In the 3-MA 45S5 group, the autophagy inhibitor 3-MA was added to 1 mg/mL 45S5. Protein immunoblotting assay (Western blot) was used to detect the expression of autophagy-associated proteins of microtubule-associated protein 1 light-chain 3β (LC3B) and P62 after 24 h of induction culture in each group. Real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect the expression of bone sialoprotein (BSP), Runt-related transcription factor 2 (Runx2), dentin sialophosphoprotein (DSPP), and dentin matrix protein-1 (DMP-1) after 7 d of induction culture. Cellular alkaline phosphatase (ALP) staining analyzed cellular ALP activity at 7 d of induction, and alizarin red staining evaluated the formation of mineralized nodules at 21 d of induction. RESULTS: The pH of the 45S5 extract culture medium was 8.65±0.01, which was not significantly different from that of the control group (P>0.05). The silicon ion concentration of the 45S5 induction culture medium was (1.56±0.07) mmol/L, which was higher than that of the control group (0.08±0.01) mmol/L (P<0.05). The calcium ion concentration of the 45S5 induction culture was (1.57±0.15) mmol/L, which was not significantly different from that of the control group (P>0.05). Western blot results showed that LC3B-Ⅱ/Ⅰ ratio increased and P62 expression decreased in the 45S5 group compared with those in the control group (P<0.05). By contrast, the ratio decreased and the expression increased in the 3-MA 45S5 group compared with those in the 45S5 group (P<0.05). RT-qPCR results showed that the expression of BSP, Runx2, DMP-1, and DSPP enhanced in the 45S5 group compared with that in the control group (P<0.05), but the expression decreased in the 3-MA 45S5 group compared with that in the 45S5 group (P<0.05). Semi-quantitative analysis of ALP staining and alizarin red staining showed that the ALP activity was enhanced, and the formation mineralized nodule increased in the 45S5 group compared with those in the control group. The ALP activity weakened, and the formation mineralized nodules were reduced in the 3-MA 45S5 group compared with that those in the 45S5 group. CONCLUSIONS Cell autophagy participates in the odontogenic differentiation of APCs induced by 1 mg/mL 45S5 in vitro.
Autophagy/drug effects* ; Cell Differentiation/drug effects* ; Odontogenesis/drug effects* ; Dental Papilla/cytology* ; Humans ; Microtubule-Associated Proteins/metabolism* ; Glass/chemistry* ; Cells, Cultured ; Core Binding Factor Alpha 1 Subunit/metabolism* ; Extracellular Matrix Proteins/metabolism* ; Ceramics/pharmacology* ; Adenine/pharmacology* ; Sialoglycoproteins/metabolism* ; Phosphoproteins/metabolism* ; Integrin-Binding Sialoprotein/metabolism* ; Alkaline Phosphatase/metabolism* ; RNA-Binding Proteins

BACKGROUND: This study aimed to determine the reasons for conversion and elucidate the safety and efficacy of transition to tenofovir alafenamide/emtricitabine/bictegravir sodium (TAF/FTC/BIC) in highly active antiretroviral therapy (HAART)-experienced HIV-infected patients in real-world settings. METHODS: We conducted a retrospective cohort study. The treatment conversion rationales, safety, and effectiveness in 1684 HIV-infected patients with previous HAART experience who switched to TAF/FTC/BIC were evaluated at Beijing Ditan Hospital from September 2021 to Auguest 2022. RESULTS: Regimen simplification (990/1684, 58.79%) was the most common reason for switching, followed by osteoporosis or osteopenia (375/1684, 22.27%), liver dysfunction (231/1684, 13.72%), decline in tenofovir alafenamide/emtricitabine/elvitegravir/cobicistat (TAF/FTC/EVG/c) with food restriction (215/1684, 12.77%), virological failure (116/1684, 6.89%), and renal dysfunction (90/1684, 5.34%). In patients receiving non-nucleotide reverse transcriptase inhibitors (NNRTI)-containing regimens, lipid panel changes 1 year after switching indicated a difference of 3.27 ± 1.10 mmol/L vs . 3.40 ± 1.59 mmol/L in triglyceride ( P  = 0.014), 4.82 ± 0.74 mmol/L vs . 4.88 ± 0.72 mmol/L in total cholesterol ( P  = 0.038), 3.09 ± 0.70 mmol/L vs . 3.18 ± 0.66 mmol/L in low-density lipoprotein ( P  <0.001), and 0.99 ± 0.11 mmol/L vs . 0.95 ± 0.10 mmol/L in high-density lipoprotein ( P  <0.001). Conversely, among patients receiving booster-containing regimens, including TAF/FTC/EVG/c and lopinavir/ritonavir (LPV/r), lipid panel changes presented decreased trends. We also observed an improved trend in viral load suppression, and alanine transaminase (ALT), aspartate transaminase (AST), estimated glomerular filtration rate (eGFR), and serum creatinine levels after the transition ( P  <0.001). CONCLUSION The transition to TAF/FTC/BIC demonstrated good treatment potency. Furthermore, this study elucidates the motivations behind the adoption of TAF/FTC/BIC in real-world scenarios, providing clinical evidence supporting the stable conversion to TAF/FTC/BIC for HAART-experienced patients.
Humans ; Antiretroviral Therapy, Highly Active/adverse effects* ; Anti-HIV Agents/adverse effects* ; HIV Infections/drug therapy* ; Tenofovir/therapeutic use* ; Retrospective Studies ; Emtricitabine/pharmacology* ; Adenine/therapeutic use* ; Lipids

Renal interstitial fibrosis (RIF) is the crucial pathway in chronic kidney disease (CKD) leading to the end-stage renal failure. However, the underlying mechanism of Shen Qi Wan (SQW) on RIF is not fully understood. In the current study, we investigated the role of Aquaporin 1 (AQP1) in SQW on tubular epithelial-to-mesenchymal transition (EMT). A RIF mouse model induced by adenine and a TGF-β1-stimulated HK-2 cell model were etablished to explore the involvement of AQP 1 in the protective effect of SQW on EMT in vitro and in vivo. Subsequently, the molecular mechanism of SQW on EMT was explored in HK-2 cells with AQP1 knockdown. The results indicated that SQW alleviated kidney injury and renal collagen deposition in the kidneys of mice induced by adenine, increased the protein expression of E-cadherin and AQP1 expression, and decreased the expression of vimentin and α-smooth muscle actin (α-SMA). Similarly, treatmement with SQW-containing serum significantly halted EMT process in TGF-β1 stimulated HK-2 cells. The expression of snail and slug was significantly upregulated in HK-2 cells after knockdown of AQP1. AQP1 knockdown also increased the mRNA expression of vimentin and α-SMA, and decreased the expression of E-cadherin. The protein expression of vimentin increased, while the expression of E-cadherin and CK-18 significantly decreased after AQP1 knockdown in HK-2 cells. These results revealed that AQP1 knockdown promoted EMT. Furthermore, AQP1 knockdown abolished the protective effect of SQW-containing serum on EMT in HK-2 cells. In sum, SQW attentuates EMT process in RIF through upregulation of the expression of AQP1.
Drugs, Chinese Herbal/pharmacology* ; Humans ; Animals ; Mice ; Male ; Cell Line ; Rats ; Kidney/physiology* ; Fibrosis/drug therapy* ; Renal Insufficiency, Chronic/drug therapy* ; Adenine ; Epithelial-Mesenchymal Transition ; Aquaporin 1/metabolism*

Objective: To determine whether the adenine base editor (ABE7.10) can be used to fix harmful mutations in the human G6PC3 gene. Methods: To investigate the safety of base-edited embryos, off-target analysis by deep sequencing was used to examine the feasibility and editing efficiency of various sgRNA expression vectors. The human HEK293T mutation models and human embryos were also used to test the feasibility and editing efficiency of correction. Results: ①The G6PC3(C295T) mutant cell model was successfully created. ②In the G6PC3(C295T) mutant cell model, three distinct Re-sgRNAs were created and corrected, with base correction efficiency ranging from 8.79% to 19.56% . ③ ABE7.10 could successfully fix mutant bases in the human pathogenic embryo test; however, base editing events had also happened in other locations. ④ With the exception of one noncoding site, which had a high safety rate, deep sequencing analysis revealed that the detection of 32 probable off-target sites was <0.5% . Conclusion: This study proposes a new base correction strategy based on human pathogenic embryos; however, it also produces a certain nontarget site editing, which needs to be further analyzed on the PAM site or editor window.
Humans ; Gene Editing ; CRISPR-Cas Systems ; Adenine ; HEK293 Cells ; Mutation ; Glucose-6-Phosphatase/metabolism*

A hyperuricemic rat model induced by adenine and ethambutol was established to investigate the anti-hyperuricemia activity and its mechanism of the flavonoid extract from saffron floral bio-residues. Sixty-seven SD rats were randomly divided into control group, model group, positive control group, and flavonoid extract groups(with 3 doses), respectively, and each group contained 11 or 12 rats. The hyperuricemic model was established by continuous oral administration of adenine(100 mg·kg~(-1)) and ethambutol(250 mg·kg~(-1)) for 7 days. At the same time, the positive control group was given allopurinol(20 mg·kg~(-1) per day) and the flavonoid extract groups were given the flavonoid extract at doses of 340, 170 and 85 mg·kg~(-1) per day, respectively. On day 8, rat serum, liver, kidney, and intestinal tissues were collected, and the levels of uric acid in serum and tissue, the xanthine oxidase activities and antioxi-dant activities in serum and liver were evaluated, and the kidney histopathology was explored. In addition, an untargeted serum metabolomics study was performed. According to the results, the flavonoid extract effectively reduced the uric acid levels in serum, kidney and ileum and inhibited the xanthine oxidase activities and elevated the antioxidant activities of serum and liver in hyperuricemic rat. At the same time, it reduced the levels of inflammation factors in kidney and protected renal function. Moreover, 68 differential metabolites of hyperuricemic rats were screened and most of which were lipids and amino acids. The flavonoid extract significantly retrieved the levels of differential metabolites in hyperuricemic rats, such as SM(d18:1/20:0), PC[18:0/18:2(92,12Z)], palmitic acid and citrulline, possibly through the following three pathways, i.e., arginine biosynthesis, glycine, serine and threonine metabolism, and histidine metabolism. To sum up, the flavonoid extract of saffron floral bio-residues lowered the uric acid level, increased the antioxidant activity, and alleviated inflammatory symptoms of hyperuricemic rats, which may be related to its inhibition of xanthine oxidase activity and regulation of serum lipids and amino acids metabolism.
Rats ; Animals ; Flavonoids/pharmacology* ; Uric Acid ; Crocus ; Xanthine Oxidase ; Ethambutol/adverse effects* ; Rats, Sprague-Dawley ; Hyperuricemia/drug therapy* ; Kidney ; Antioxidants/pharmacology* ; Plant Extracts/adverse effects* ; Amino Acids ; Adenine/adverse effects* ; Lipids

In contrast to the well-established genomic 5-methylcytosine (5mC), the existence of N⁶-methyladenine (6 mA) in eukaryotic genomes was discovered only recently. Initial studies found that it was actively regulated in cancer cells, suggesting its involvement in the process of carcinogenesis. However, the contribution of 6 mA in tongue squamous cell carcinoma (TSCC) still remains uncharacterized. In this study, a pan-cancer type analysis was first performed, which revealed enhanced 6 mA metabolism in diverse cancer types. The study was then focused on the regulation of 6 mA metabolism, as well as its effects on TSCC cells. To these aspects, genome 6 mA level was found greatly increased in TSCC tissues and cultured cells. By knocking down 6 mA methylases N6AMT1 and METTL4, the level of genomic 6 mA was decreased in TSCC cells. This led to suppressed colony formation and cell migration. By contrast, knockdown of 6 mA demethylase ALKBH1 resulted in an increased 6 mA level, enhanced colony formation, and cell migration. Further study suggested that regulation of the NF-κB pathway might contribute to the enhanced migration of TSCC cells. Therefore, in the case of TSCC, we have shown that genomic 6 mA modification is involved in the proliferation and migration of cancer cells.
AlkB Homolog 1, Histone H2a Dioxygenase/metabolism* ; Carcinoma, Squamous Cell/pathology* ; Cell Line, Tumor ; Cell Movement/genetics* ; Cell Proliferation ; Gene Expression Regulation, Neoplastic ; Humans ; Site-Specific DNA-Methyltransferase (Adenine-Specific)/metabolism* ; Tongue Neoplasms/metabolism*

Chinese hamster ovary (CHO) cells are the preferred host cells for the production of complex recombinant therapeutic proteins. Adenine phosphoribosyltransferase (APRT) is a key enzyme in the purine biosynthesis step that catalyzes the condensation of adenine with phosphoribosylate to form adenosine phosphate AMP. In this study, the gene editing technique was used to knock out the aprt gene in CHO cells. Subsequently, the biological properties of APRT-KO CHO cell lines were investigated. A control vector expressed an enhanced green fluorescent protein (EGFP) and an attenuation vector (containing an aprt-attenuated expression cassette and EGFP) were constructed and transfected into APRT-deficient and wild-type CHO cells, respectively. The stable transfected cell pools were subcultured for 60 generations and the mean fluorescence intensity of EGFP in the recombinant CHO cells was detected by flow cytometry to analyze the EGFP expression stability. PCR amplification and sequencing showed that the aprt gene in CHO cell was successfully knocked out. The obtained APRT-deficient CHO cell line had no significant difference from the wild-type CHO cells in terms of cell morphology, growth, proliferation, and doubling time. The transient expression results indicated that compared with the wild-type CHO cells, the expression of EGFP in the APRT-deficient CHO cells transfected with the control vector and the attenuation vector increased by 42%±6% and 56%±9%, respectively. Especially, the EGFP expression levels in APRT-deficient cells transfected with the attenuation vector were significantly higher than those in wild-type CHO cells (P < 0.05). The findings suggest that the APRT-deficient CHO cell line can significantly improve the long-term expression stability of recombinant proteins. This may provide an effective cell engineering strategy for establishing an efficient and stable CHO cell expression system.
Adenine/metabolism* ; Adenine Nucleotides ; Adenine Phosphoribosyltransferase/genetics* ; Adenosine Monophosphate ; Animals ; CHO Cells ; Cricetinae ; Cricetulus ; Recombinant Proteins/genetics*