Long-term follow-up in outpatients with mildly elevated pulmonary artery systolic pressure on echocardiography: a single-centre retrospective cohort study in Shanghai, China.

OBJECTIVE: To investigate the correlation between mildly elevated pulmonary artery systolic pressure (PASP) on echocardiography and mortality, as well as long-term changes in PASP. DESIGN: Retrospective cohort study. SETTING: Shanghai, China, a single centre. PARTICIPANTS: A total of 910 patients were enrolled in this study. From January to June 2016, 1869 patients underwent echocardiography at the Zhongshan Hospital affiliated with Fudan University. Patients with malignant tumours, previous heart or other solid organ transplantation, previous or scheduled ventricular assist device implantation, severe kidney dysfunction (uraemia and patients on dialysis) and a life expectancy of less than 1 year for any medical condition were excluded. INTERVENTIONS: No interventions were done. PRIMARY AND SECONDARY OUTCOME MEASURES: The predictors of death in patients with mild echocardiographic pulmonary hypertension were analysed using univariate and multivariate Cox regression analyses. Paired t-tests were used to calculate changes in the PASP values at baseline and follow-up for different patient groups. RESULTS: The 5-year survival of patients was 93.2%. Patients were grouped according to whether they had combined organic heart disease (OHD). The PASP value was an independent predictor of all-cause mortality in patients with OHD, with each 1 mm Hg increase associated with an HR of 1.02 (95% CI: 1.01-1.03, p=0.038) but not in patients without OHD. Of the total, 46% (419/910) of the patients with 5-6 years of echocardiography were investigated for changes in the PASP value. We found significant PASP reduction in patients without OHD (42.8±2.4 mm Hg vs 39.3±8.2 mm Hg, p<0.001), but no significant change was observed for patients with OHD (42.8±2.5 mm Hg vs 42.4±8.8 mm Hg, p=0.339). CONCLUSIONS: The PASP was associated with all-cause mortality in patients with OHD and mildly elevated PASP compared with patients without OHD. After 5-6 years of follow-up, the PASP on echocardiography was not further elevated in patients without OHD.

Long-term outcomes in patients with bicuspid valve stenosis and aortic dilation undergoing transcatheter valve implantation.

BACKGROUND: To date, whether ascending aorta dilation (AAD) should be considered a contraindication for transcatheter aortic valve replacement (TAVR) remains a topic of debate.. OBJECTIVE: The study investigated the clinical outcome of TAVR in patients with bicuspid aortic valve stenosis (BAV-AS) complicated by AAD. METHODS: We included patients with BAV-AS who underwent TAVR between 2012 and 2019. We collected patient perioperative clinical data., tracked clinical outcomes for over four years post-TAVR, and obtained echocardiography images one year postoperatively. The Kaplan-Meier method was employed for analyzing both unadjusted and adjusted survival data, which was compared using the log-rank test. COX regression and nomograms were used to assess the impact of AAD on post-TAVR clinical outcomes in patients with aortic stenosis (AS), with all-cause mortality as the primary clinical endpoint. RESULTS: A total of 111 BAV patients were included in this study. Long-term follow-up showed an increased mortality risk in patients with BAV-AAD (adjusted Kaplan-Meier analysis: P = .02/0.001). Cox correlation analysis indicated that age (OR = 1.137; P = .034), AAD (OR = 3.51; P = .038), and postoperative left ventricular pressure (LVSP) (OR: 0.959; P = .044) were predictive factors for mortality more than four years after TAVR in patients with BAV. The area under the curve of the Nomogram predicting long-term survival for the training set of patients based on the above metrics was 0.845 (95% CI: 0.696-0.994). Short-term cardiac ultrasound follow-up showed a more rapid rate of AA expansion (0.29 [0-0.34] vs. -1 [-3.3-1] mm/month, P = .001) and a smaller proportion of AA diameter reduction (7.1% vs. 53.7%, P = .001) in patients who died. CONCLUSIONS: Patients with BAV-AAD-AS treated with TAVR have an increased risk of long-term mortality, and clinical prediction models, including AAD age and postoperative LVSP, may predict long-term patient survival. CONDENSED ABSTRACT: The study investigated the clinical outcome of transcatheter aortic valve replacement (TAVR) in patients with bicuspid aortic valve stenosis (BAV-AS) complicated by ascending aorta dilation (AAD). Patients with BAV-AAD-AS treated with TAVR have an increased risk of long-term mortality. AAD, age and postoperative LVSP, may predict long-term patient survival. Short-term cardiac ultrasound follow-up showed a more rapid rate of AA expansion and a smaller proportion of AA diameter reduction in patients who died. A high postoperative AAD expansion rate may indicate an adverse clinical outcome. Surgery regimens for tolerable BAV-AADs and can be considered as a treatment option.

Targeting Macrophages: Therapeutic Approaches in Diabetic Kidney Disease.

Diabetes is not solely a metabolic disorder but also involves inflammatory processes. The immune response it incites is a primary contributor to damage in target organs. Research indicates that during the initial phases of diabetic nephropathy, macrophages infiltrate the kidneys alongside lymphocytes, initiating a cascade of inflammatory reactions. The interplay between macrophages and other renal cells is pivotal in the advancement of kidney disease within a hyperglycemic milieu. While M1 macrophages react to the inflammatory stimuli induced by elevated glucose levels early in the disease progression, their subsequent transition to M2 macrophages, which possess anti-inflammatory and tissue repair properties, also contributes to fibrosis in the later stages of nephropathy by transforming into myofibroblasts. Comprehending the diverse functions of macrophages in diabetic kidney disease and regulating their activity could offer therapeutic benefits for managing this condition.

Medical Management of Pulmonary Arterial Hypertension: Current Approaches and Investigational Drugs.

Pulmonary arterial hypertension (PAH) is a malignant pulmonary vascular syndrome characterized by a progressive increase in pulmonary vascular resistance and pulmonary arterial pressure, which eventually leads to right heart failure and even death. Although the exact mechanism of PAH is not fully understood, pulmonary vasoconstriction, vascular remodeling, immune and inflammatory responses, and thrombosis are thought to be involved in the development and progression of PAH. In the era of non-targeted agents, PAH had a very dismal prognosis with a median survival time of only 2.8 years. With the deep understanding of the pathophysiological mechanism of PAH as well as advances in drug research, PAH-specific therapeutic drugs have developed rapidly in the past 30 years, but they primarily focus on the three classical signaling pathways, namely the endothelin pathway, nitric oxide pathway, and prostacyclin pathway. These drugs dramatically improved pulmonary hemodynamics, cardiac function, exercise tolerance, quality of life, and prognosis in PAH patients, but could only reduce pulmonary arterial pressure and right ventricular afterload to a limited extent. Current targeted agents delay the progression of PAH but cannot fundamentally reverse pulmonary vascular remodeling. Through unremitting efforts, new therapeutic drugs such as sotatercept have emerged, injecting new vitality into this field. This review comprehensively summarizes the general treatments for PAH, including inotropes and vasopressors, diuretics, anticoagulants, general vasodilators, and anemia management. Additionally, this review elaborates the pharmacological properties and recent research progress of twelve specific drugs targeting three classical signaling pathways, as well as dual-, sequential triple-, and initial triple-therapy strategies based on the aforementioned targeted agents. More crucially, the search for novel therapeutic targets for PAH has never stopped, with great progress in recent years, and this review outlines the potential PAH therapeutic agents currently in the exploratory stage to provide new directions for the treatment of PAH and improve the long-term prognosis of PAH patients.

Discovery of compounds that reactivate p53 mutants in vitro and in vivo.

The tumor suppressor p53 is the most frequently mutated protein in human cancer. The majority of these mutations are missense mutations in the DNA binding domain of p53. Restoring p53 tumor suppressor function could have a major impact on the therapy for a wide range of cancers. Here we report a virtual screening approach that identified several small molecules with p53 reactivation activities. The UCI-LC0023 compound series was studied in detail and was shown to bind p53, induce a conformational change in mutant p53, restore the ability of p53 hotspot mutants to associate with chromatin, reestablish sequence-specific DNA binding of a p53 mutant in a reconstituted in vitro system, induce p53-dependent transcription programs, and prevent progression of tumors carrying mutant p53, but not p53null or p53WT alleles. Our study demonstrates feasibility of a computation-guided approach to identify small molecule corrector drugs for p53 hotspot mutations.

Relationship Between Serum Concentration of Adrenomedullin and Myocardial Ischemic T Wave Changes in Patients With Lung Cancer.

Background: Patients with lung cancer are at increased risk for the development of cardiovascular diseases. Molecular markers for early diagnosis of cardiac ischemia are of great significance for the early prevention of cardiovascular events in patients with lung cancer. By evaluating the relationship between adrenomedullin (ADM) and myocardial ischemic T wave changes, the clinical value of circulating ADM as a predictor of myocardial ischemia in patients with lung cancer is confirmed. Methods: We enrolled patients with lung cancer and healthy people from 2019 to 2021 and extracted a detailed ECG parameter. After adjustment for potential confounders, logistic regression was used to assess the association of clinical data. We performed analyses on differences in T wave between patients with lung cancer and healthy people, and the relationship between T wave and ADM among patients with lung cancer. Receiver operator characteristic (ROC) curves were drawn to confirm the diagnostic value of biomarkers. Results: After adjusting for potential confounders, the incidence of T wave inversion or flattening in patients with lung cancer was higher than in healthy people (OR: 3.3228, P = 0.02). Also, further analysis of the data of lung cancer patients revealed that the ADM in lung cancer patients with T wave inversion or flat was higher than those with normal T wave (189.8 ± 51.9 vs. 131.9 ± 38.4, p < 0.001). The area under the ROC curve was 0.8137. Conclusion: Among the patients with lung cancer, serum ADM concentration is associated with the incidence of the abnormal T wave. ADM might be a potentially valuable predictor for heart ischemia in patients with lung cancer.

Identification and expression pattern of the sex determination gene fruitless-like in Cherax quadricarinatus.

The fruitless (fru) gene has an important function in the courtship behavior and sex determination pathway of Drosophila melanogaster; however, the fru gene has never been reported in shrimps. In this study, the fruitless-like gene was identified in Cherax quadricarinatus (Cqfru) and is reported here for the first time. A sequence analysis revealed a conserved BTB domain in Cqfru which is the same as fru in D. melanogaster. An analysis of the expression level of Cqfru showed that it was highly expressed in the gastrula stage during embryonic development. Furthermore, in situ hybridization and expression distribution in tissues showed that its sexually dimorphic expression may be focused on the hepatopancreas, brains, and gonads. The gonads, brains, and hepatopancreas of males had a higher expression level of Cqfru than those of females; however, the expression level of the abdominal ganglion was found to be higher in females than in males in this study. The results of an RNA interference treatment showed that a knockdown of Cqfru reduced the expression of the insulin-like androgenic gland hormone (IAG) and tumor necrosis factor (TNF). The characteristic fru gene in shrimps is reported here for the first time, with the results providing basic information for research into the sex-determination mechanism in C. quadricarinatus.

Neuregulin-1ß Alleviates Sepsis-Induced Skeletal Muscle Atrophy by Inhibiting Autophagy via AKT/mTOR Signaling Pathway in Rats.

BACKGROUND: Several studies have shown that excessive protein degradation is a major cause of skeletal muscle atrophy induced by sepsis, and autophagy is the main pathway participating in protein degradation. However, the role of autophagy in sepsis is still controversial. Previously, we found that neuregulin-1ß (NRG-1ß) alleviated sepsis-induced diaphragm atrophy through the phosphatidylinositol-3 kinase signaling pathway. Akt/mechanistic target of rapamycin (mTOR) is a classic signaling pathway to regulate autophagy, which maintains intracellular homeostasis. This study aimed to investigate whether NRG-1ß could alleviate sepsis-induced skeletal muscle atrophy by regulating autophagy. METHODS: L6 rat myoblast cells were differentiated using 2% fetal bovine serum into myotubes, which were divided into four groups: Con group treated with normal serum; Sep group treated with septic serum to form a sepsis cell model; septic serum + NRG-1ß (SN) group treated with septic serum for 24 h followed by injection with NRG-1ß and incubation for another 48 h; and serum+NRG-1ß+LY294002 group, in which the PI3K inhibitor LY294002 was added 30 min before NRG-1ß, and other treatments were similar to those in SN group. Effects of NRG-1ß were also evaluated in vivo using Sprague-Dawley (SD) rats, in which sepsis was induced by cecal ligation and puncture (CLP). RESULTS: In L6 myotubes treated with septic serum, the expression of autophagy-related proteins UNC-51 like kinase 1, p-Beclin-1, and Beclin-1, and the ratio of LC3B II/I were highly increased, while protein p62 expression was decreased, indicating that autophagy was excessively activated. Moreover, NRG-1 expression was decreased, as detected by confocal immunofluorescence and western blotting. Upon exogenous addition of NRG-1ß, autophagy was inhibited by the activation of Akt/mTOR signaling pathway, and cell viability was also increased. These effects disappeared in the presence of LY294002. In SD rats, sepsis was induced by CLP. NRG-1ß was shown to inhibit autophagy in these rats via the Akt/mTOR pathway, leading to increased body weight of the septic SD rats and alleviation of atrophy of the tibialis anterior muscle. CONCLUSION: NRG-1ß could alleviate sepsis-induced skeletal muscle atrophy by inhibiting autophagy via the AKT/mTOR signaling pathway.

Localized Proteolysis for the Construction of Intracellular Asymmetry in Escherichia coli.

Protein-level regulations have gained importance in building synthetic circuits, as they offer a potential advantage in the speed of operation compared to gene regulation circuits. In nature, localized protein degradation is prevalent in polarizing cellular signaling. We, therefore, set out to systematically investigate whether localized proteolysis can be employed to construct intracellular asymmetry in Escherichia coli. We demonstrate that, by inserting a cognate cleavage site between the reporter and C-terminal degron, the unstable reporter can be stabilized in the presence of the tobacco etch virus protease. Furthermore, the split protease can be functionally reconstituted by the PopZ-based polarity system to exert localized proteolysis. Selective stabilization of the unstable reporter at the PopZ pole can lead to intracellular asymmetry in E. coli. Our study provides complementary evidence to support that localized proteolysis may be a strategy for polarization in developmental cell biology. Circuits designed in this study may also help to expand the synthetic biology repository for the engineering of synthetic morphogenesis, particularly for processes that require rapid control of local protein abundance.

New progress in elucidating the relationship between cancer therapy and cardiovascular toxicity.

Onco-cardiology is an emerging field linking cancer with cardiovascular injury. Understanding the mechanism of cardiac injury helps improve the quality of life of cancer survivors. A series of studies on adverse reactions to cancer or oncological treatments has indicated that adverse cardiovascular events related to cancer treatments may occur over a longer period of survival, and even years after therapy has concluded. Current cancer therapies, including chemotherapy, radiotherapy, targeted therapy, and immunotherapy, have been found to have latent cardiovascular toxicity. These toxic effects are often progressive and irreversible and ultimately lead to cardiovascular events such as heart failure, hypertension, coronary heart diseases, arrhythmia, and thromboembolism. Therefore, more emphasis should be placed on revealing the mechanism of cancer treatment-related cardiovascular toxicity. This would help to guide prevention, diagnosis, and treatment of CVDs in cancer survivors.

Lipid remodeling in response to methionine stress in MDA-MBA-468 triple-negative breast cancer cells.

Methionine (Met) is an essential amino acid and critical precursor to the cellular methyl donor S-adenosylmethionine. Unlike nontransformed cells, cancer cells have a unique metabolic requirement for Met and are unable to proliferate in growth media where Met is replaced with its metabolic precursor, homocysteine. This metabolic vulnerability is common among cancer cells regardless of tissue origin and is known as "methionine dependence", "methionine stress sensitivity", or the Hoffman effect. The response of lipids to Met stress, however, is not well-understood. Using mass spectroscopy, label-free vibrational microscopy, and next-generation sequencing, we characterize the response of lipids to Met stress in the triple-negative breast cancer cell line MDA-MB-468 and its Met stress insensitive derivative, MDA-MB-468res-R8. Lipidome analysis identified an immediate, global decrease in lipid abundances with the exception of triglycerides and an increase in lipid droplets in response to Met stress specifically in MDA-MB-468 cells. Furthermore, specific gene expression changes were observed as a secondary response to Met stress in MDA-MB-468, resulting in a downregulation of fatty acid metabolic genes and an upregulation of genes in the unfolded protein response pathway. We conclude that the extensive changes in lipid abundance during Met stress is a direct consequence of the modified metabolic profile previously described in Met stress-sensitive cells. The changes in lipid abundance likely results in changes in membrane composition inducing the unfolded protein response we observe.

Isolation and Characterization of Methionine-Independent Clones from Methionine-Dependent Cancer Cells.

Unlike normal cells, transformed cells are unable to grow when methionine in the growth media is restricted. Reversion to methionine independence is a rare event in transformed and malignant cells. Methionine-independent revertants provide an excellent system to identify metabolic signatures and molecular characteristics associated with methionine dependency of transformed cells. Revertants maintain the genetic background and general growth behavior of the parental cell line, except that they proliferate under methionine restriction such as in methionine-free media supplemented with homocysteine. Here we describe a general approach to generate methionine-independent revertants using the example of the triple-negative breast cancer cell line MDA-MB-468. To validate and characterize reversion we describe assays to evaluate cell proliferation and anchorage-independent growth in soft agar.

[Determination of five pesticides in fishpond by SPE-GC/MS].

OBJECTIVE: To establish the solid phase extraction (SPE) with GC/MS technology for fish poisoning cases to determine five pesticides in fishpond. METHODS: By three solid phase extraction column including Oasis HLB cartridge, Bond Elut C18 and SampliQ C18, the recovery rate was compared to extract and purify five pesticides in fishpond. The effects of different kinds and dosages of eluents on extract rate were also reviewed. RESULTS: Using Bond Elut C18 as solid phase extraction column and 3 mL benzene as eluent, the linear range of mass concentration of five pesticides in fishpond was 1-50 µg/mL, and the correlation coefficient was 0.996 2-0.999 6. The limit of detection was 3.4-26 µg/L and the recovery was 61.49%-102.48%. The relative standard deviations was less than or equal to 3.01%. CONCLU-SION: With high sensitivity, good accuracy and precision, SPE-GC/MS has simple and quick operation and less solvent. It can be applied to determination of five pesticides in fishpond.

[Analysis of pesticides in blood specimen by GC/MS with accelerated solvent extraction].

OBJECTIVE: To develop the accelerated solvent extraction (ASE) for determining pesticides present in blood samples. METHODS: Pesticides were extracted by ASE with optimized parameters to study recovery rate affected by extraction temperature, time and agent. GC/MS was used to perform quantitative analysis. RESULTS: The recovery rates of eight pesticides were 70.6%-92.4%. The coefficient of variation was less than 5.0%. A good linear relationship was obtained at the concentration range of 0.5-5.0 microg/mL. CONCLUSION: The method was fast and simple with high recovery rate and good repeatability. It can be applied to analyze pesticides present in the blood specimen.

S-adenosylmethionine limitation induces p38 mitogen-activated protein kinase and triggers cell cycle arrest in G1.

The primary methyl group donor S-adenosylmethionine (SAM) is important for a plethora of cellular pathways including methylation of nucleic acids, proteins, and the 5' cap structure of mRNAs, as well as biosynthesis of phospholipids and polyamines. In addition, because it is the cofactor for chromatin methylation, SAM is an important metabolite for the establishment and maintenance of epigenetic marks. Here, we demonstrate that cells halt proliferation when SAM levels become low. Cell cycle arrest occurs primarily in the G1 phase of the cell cycle and is accompanied by activation of the mitogen-activated protein kinase p38 (MAPK14) and subsequent phosphorylation of MAPK-activated protein kinase-2 (MK2). Surprisingly, Cdk4 activity remains high during cell cycle arrest, whereas Cdk2 activity decreases concomitantly with cyclin E levels. Cell cycle arrest was induced by both pharmacological and genetic manipulation of SAM synthesis through inhibition or downregulation of methionine adenosyltransferase, respectively. Depletion of methionine, the precursor of SAM, from the growth medium induced a similar cell cycle arrest. Unexpectedly, neither methionine depletion nor inhibition of methionine adenosyltransferase significantly affected mTORC1 activity, suggesting that the cellular response to SAM limitation is independent from this major nutrient-sensing pathway. These results demonstrate a G1 cell cycle checkpoint that responds to limiting levels of the principal cellular methyl group donor S-adenosylmethionine. This metabolic checkpoint might play important roles in maintenance of epigenetic stability and general cellular integrity.

Computational identification of a transiently open L1/S3 pocket for reactivation of mutant p53.

The tumour suppressor p53 is the most frequently mutated gene in human cancer. Reactivation of mutant p53 by small molecules is an exciting potential cancer therapy. Although several compounds restore wild-type function to mutant p53, their binding sites and mechanisms of action are elusive. Here computational methods identify a transiently open binding pocket between loop L1 and sheet S3 of the p53 core domain. Mutation of residue Cys124, located at the centre of the pocket, abolishes p53 reactivation of mutant R175H by PRIMA-1, a known reactivation compound. Ensemble-based virtual screening against this newly revealed pocket selects stictic acid as a potential p53 reactivation compound. In human osteosarcoma cells, stictic acid exhibits dose-dependent reactivation of p21 expression for mutant R175H more strongly than does PRIMA-1. These results indicate the L1/S3 pocket as a target for pharmaceutical reactivation of p53 mutants.

Downregulation of Cdc6 and pre-replication complexes in response to methionine stress in breast cancer cells.

Methionine and homocysteine are metabolites in the transmethylation pathway leading to synthesis of the methyl-donor S-adenosylmethionine (SAM). Most cancer cells stop proliferating during methionine stress conditions, when methionine is replaced in the growth media by its immediate metabolic precursor homocysteine (Met-Hcy+). Non-transformed cells proliferate in Met-Hcy+ media, making the methionine metabolic requirement of cancer cells an attractive target for therapy, yet there is relatively little known about the molecular mechanisms governing the methionine stress response in cancer cells. To study this phenomenon in breast cancer cells, we selected methionine-independent-resistant cell lines derived from MDAMB468 breast cancer cells. Resistant cells grew normally in Met-Hcy+ media, whereas their parental MDAMB468 cells rapidly arrest in the G 1 phase. Remarkably, supplementing Met-Hcy+ growth media with S-adenosylmethionine suppressed the cell proliferation defects, indicating that methionine stress is a consequence of SAM limitation rather than low amino acid concentrations. Accordingly, mTORC1 activity, the primary effector responding to amino acid limitation, remained high. However, we found that levels of the replication factor Cdc6 decreased and pre-replication complexes were destabilized in methionine-stressed MDAMB468 but not resistant cells. Our study characterizes metabolite requirements and cell cycle responses that occur during methionine stress in breast cancer cells and helps explain the metabolic uniqueness of cancer cells.

Multiple clonal MLL fusions in a patient receiving CHOP-based chemotherapy.

MLL rearrangements were analysed in the blood of a patient receiving chemotherapy for diffuse large B-cell lymphoma using inverse polymerase chain reaction targeting exon 12, parallel sequencing and a custom algorithm design. Of thirteen MLL rearrangements detected, five were capable of generating MLL fusion genes, including MLL-MLLT3, the most common fusion in acute myeloid leukaemia (AML). Other fusions, all previously clinically unobserved, included MLL-NKD1, a fusion to the negative regulator of Wnt/ß-catenin signaling, a pathway linked to leukaemic cell proliferation. The majority of the fusions exhibited clonal persistence from before treatment until 6 months post-chemotherapy, suggesting the fusions may confer a survival advantage to the mutant clone. MLL breakpoints were partly clustered at a specific location, indicating commonality in the process of their formation. Further, the same MLL breakpoint location exhibited a 50-100-fold increase in C to T transitions, consistent with attack by activation-induced cytidine deaminase (AICDA). As is also observed in AML and acute lymphoblastic leukaemia, in this single patient setting, MLL is capable of interacting with multiple fusion partners. This finding defines a discrete site of MLL susceptibility to fragmentation, linked to possible deregulation of AICDA function.

Identification of a putative human mitochondrial thymidine monophosphate kinase associated with monocytic/macrophage terminal differentiation.

Mitochondrial DNA synthesis requires the supply of thymidine triphosphate (dTTP) independent of nuclear DNA replication. In resting and differentiating cells that withdraw from the cell cycle, mitochondrial thymidine kinase 2 (TK2) mediates thymidine monophosphate (dTMP) formation for the dTTP biosynthesis in mitochondria. However, a thymidine monophosphate kinase (TMPK) that phosphorylates dTMP to form thymidine diphosphate (dTDP) in mitochondria remains undefined. Here, we identified an expressed sequence tag cDNA, which encodes a TMPK with a mitochondrial import sequence at its N-terminus designated as TMPK2. HeLa cells expressing TMPK2 fused to green fluorescent protein (GFP) displayed green fluorescence in mitochondria. Over-expression of TMPK2 increased the steady-state level of cellular dTTP and promoted the conversion of radioactive labeled-thymidine and -dTMP to dTDP and dTTP in mitochondria. TMPK2 RNA was detected in several tissues and erythroblastoma cell lines. We also generated TMPK2 antibody and used it for immunofluorescence staining to demonstrate endogenous expression of TMPK2 in mitochondria of erythroblastoma cells. Finally, we showed that TMPK2 protein expression was upregulated in monocyte/macrophage differentiating cells, suggesting the coordinated regulation of TMPK2 expression with the terminal differentiation program.