Adenosine triphosphate (ATP) regeneration systems are essential for efficient biocatalytic phosphoryl transfer reactions. Polyphosphate kinase (PPK) is a versatile enzyme that can transfer phosphate groups among adenosine monophosphate (AMP), adenosine diphosphate (ADP), ATP, and polyphosphate (Poly P). Utilization of PPK is an attractive solution to address the problem of ATP regeneration due to its ability to use a variety of inexpensive and stable Poly P salts as phosphate group donors. This review comprehensively summarizes the structural characteristics and catalytic mechanisms of different types of PPKs, as well as the variations in enzyme activity, catalytic efficiency, stability, and coenzyme preference observed in PPKs from different sources. Moreover, recent advances in PPK-mediated ATP regeneration systems and protein engineering of wild-type PPK are summarized.
Adenosine Triphosphate/metabolism* ; Adenosine Monophosphate ; Polyphosphates/metabolism* ; Catalysis ; Regeneration

AMP-Activated Protein Kinases/metabolism* ; Adenosine Monophosphate/metabolism* ; Kidney/metabolism* ; Phosphorylation

OBJECTIVE: To investigate the effects and mechanisms of Kindlin-2 on uterus development and reproductive capacity in female mice. METHODS: Cdh16-Cre tool mice and Kindlin-2^flox/flox mice were used to construct the mouse model of uterus specific knockout of Kindlin-2, and the effects of Kindlin-2 deletion on uterine development and reproduction capacity of female mice were observed. High expression and knockdown of Kindlin-2 in endometrial cancer cell lines HEC-1 and Ish were used to detect the regulation of mammalian target of rapamycin (mTOR) signaling pathway. In addition, uterine proteins of the female mice with specific knockout of Kindlin-2 and female mice in the control group were extracted to detect the protein levels of key molecules of mTOR signaling pathway and Hippo signaling pathway. RESULTS: The mouse model of uterine specific knockout of Kindlin-2 was successfully constructed. The knockout efficiency of Kindlin-2 in mouse uterus was identified and verified by mouse tail polymerase chain reaction (PCR), Western blot protein identification, immunohistochemical staining (IHC) and other methods. Compared with the control group, the female mice with uterus specific deletion of Kindlin-2 lost weight, seriously impaired reproductive ability, and the number of newborn mice decreased, but the proportion of the female mice and male mice in the newborn mice did not change. Hematoxylin eosin staining (HE) experiment showed that the endometrium of Kindlin-2 knockout group was incomplete and the thickness of uterine wall became thinner. In terms of mechanism, the deletion of Kindlin-2 in endo-metrial cancer cell lines HEC-1 and Ish could downregulate the protein levels of mTOR, phosphorylated mTOR, adenosine monophosphate-activated protein kinase (AMPK), phosphorylated AMPK and phosphorylated ribosomal protein S6 (S6), and the mTOR signal pathway was inhibited. It was found that the specific deletion of Kindlin-2 could upregulate the protein levels of Mps one binding 1 (MOB1) and phosphorylated Yes-associated protein (YAP) in the uterus of the female mice, and the Hippo signal pathway was activated. CONCLUSION Kindlin-2 inhibits the development of uterus by inhibiting mTOR signal pathway and activating Hippo signal pathway, thereby inhibiting the fertility of female mice.
AMP-Activated Protein Kinases/metabolism* ; Adenosine Monophosphate/metabolism* ; Animals ; Cadherins/metabolism* ; Cytoskeletal Proteins/metabolism* ; Endometrium/metabolism* ; Eosine Yellowish-(YS)/metabolism* ; Female ; Hematoxylin/metabolism* ; Hippo Signaling Pathway ; Male ; Mammals/metabolism* ; Mice ; Muscle Proteins ; Ribosomal Protein S6/metabolism* ; Sirolimus/metabolism* ; TOR Serine-Threonine Kinases/metabolism* ; YAP-Signaling Proteins

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*

The coronavirus disease 2019 (COVID-19) pandemic is caused by infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is spread primary via respiratory droplets and infects the lungs. Currently widely used cell lines and animals are unable to accurately mimic human physiological conditions because of the abnormal status of cell lines (transformed or cancer cells) and species differences between animals and humans. Organoids are stem cell-derived self-organized three-dimensional culture in vitro and model the physiological conditions of natural organs. Here we showed that SARS-CoV-2 infected and extensively replicated in human embryonic stem cells (hESCs)-derived lung organoids, including airway and alveolar organoids which covered the complete infection and spread route for SARS-CoV-2 within lungs. The infected cells were ciliated, club, and alveolar type 2 (AT2) cells, which were sequentially located from the proximal to the distal airway and terminal alveoli, respectively. Additionally, RNA-seq revealed early cell response to virus infection including an unexpected downregulation of the metabolic processes, especially lipid metabolism, in addition to the well-known upregulation of immune response. Further, Remdesivir and a human neutralizing antibody potently inhibited SARS-CoV-2 replication in lung organoids. Therefore, human lung organoids can serve as a pathophysiological model to investigate the underlying mechanism of SARS-CoV-2 infection and to discover and test therapeutic drugs for COVID-19.
Adenosine Monophosphate/therapeutic use* ; Alanine/therapeutic use* ; Alveolar Epithelial Cells/virology* ; Antibodies, Neutralizing/therapeutic use* ; COVID-19/virology* ; Down-Regulation ; Drug Discovery ; Human Embryonic Stem Cells/metabolism* ; Humans ; Immunity ; Lipid Metabolism ; Lung/virology* ; RNA, Viral/metabolism* ; SARS-CoV-2/physiology* ; Virus Replication/drug effects*

AMP-Activated Protein Kinases/metabolism* ; Adenosine ; Adenosine Monophosphate ; Cell Proliferation ; Endometrial Neoplasms/drug therapy* ; Female ; Humans ; Liraglutide ; Phosphorylation ; Protein Kinases ; Signal Transduction

Adenosine 5'-monophosphate-activated protein activated protein kinase (AMPK), a heterotrimeric complex, is an important kinase to regulate glycolipid metabolism and energy balance involved in a variety physiological processes in human body. Many research indicated that the function and activity of AMPK were closely related to inflammation, diabetes and cancers. Recent reports show that inhibition of metformin (a first-line drug) on hepatic glucose in patients with hyperglycemia is associated with AMPK pathway, suggesting that targeting AMPK may be one of the effective strategies for the prevention and treatment of a variety of chronic diseases. Here, we review research progress on the structure, activation and regulation of AMPK in glycolipid metabolism to provide an insight into the basic and clinical research of diabetes therapy.
AMP-Activated Protein Kinases ; Adenosine ; Adenosine Monophosphate ; Energy Metabolism ; Enzyme Activation ; Glycolipids ; Humans

Adenosine Monophosphate ; metabolism ; Genetic Pleiotropy ; HSP70 Heat-Shock Proteins ; metabolism ; Humans ; Neurodegenerative Diseases ; metabolism

To interact with the egg, the spermatozoon must undergo several biochemical and motility modifications in the female reproductive tract, collectively called capacitation. Only capacitated sperm can undergo acrosomal exocytosis, near or on the egg, a process that allows the sperm to penetrate and fertilize the egg. In the present study, we investigated the involvement of cyclic adenosine monophosphate (cAMP)-dependent processes on acrosomal exocytosis. Inhibition of protein kinase A (PKA) at the end of capacitation induced acrosomal exocytosis. This process is cAMP-dependent; however, the addition of relatively high concentration of the membrane-permeable 8-bromo-cAMP (8Br-cAMP, 0.1 mmol l^-1) analog induced significant inhibition of the acrosomal exocytosis. The induction of acrosomal exocytosis by PKA inhibition was significantly inhibited by an exchange protein directly activated by cAMP (EPAC) ESI09 inhibitor. The EPAC selective substrate activated AE at relatively low concentrations (0.02-0.1 μmol l^-1), whereas higher concentrations (>5 μmol l^-1) were inhibitory to the AE induced by PKA inhibition. Inhibition of PKA revealed about 50% increase in intracellular cAMP levels, conditions under which EPAC can be activated to induce the AE. Induction of AE by activating the actin severing-protein, gelsolin, which causes F-actin dispersion, was inhibited by the EPAC inhibitor. The AE induced by PKA inhibition was mediated by phospholipase C activity but not by the Ca²⁺-channel, CatSper. Thus, inhibition of PKA at the end of the capacitation process induced EPAC/phospholipase C-dependent acrosomal exocytosis. EPAC mediates F-actin depolymerization and/or activation of effectors downstream to F-actin breakdown that lead to acrosomal exocytosis.
8-Bromo Cyclic Adenosine Monophosphate/pharmacology* ; Acrosome/metabolism* ; Acrosome Reaction/drug effects* ; Calcimycin/pharmacology* ; Cyclic AMP/metabolism* ; Cyclic AMP-Dependent Protein Kinases/antagonists & inhibitors* ; Exocytosis/drug effects* ; Guanine Nucleotide Exchange Factors/metabolism* ; Humans ; Male ; Protein Kinase Inhibitors/pharmacology* ; Signal Transduction/drug effects* ; Spermatozoa/metabolism* ; Thapsigargin/pharmacology*

In recent years, as the aging population grows, aging-induced cognitive impairments including dementia and Alzheimer's disease (AD) have become the biggest challenges for global public health and social care. Therefore, the development of potential therapeutic drugs for aging-associated cognitive impairment is essential. Metabolic dysregulation has been considered to be a key factor that affects aging and dementia. Adenosine monophosphate (AMP)-activated protein kinase (AMPK) is a primary sensor of cellular energy states and regulates cellular energy metabolism. Metformin (1,1-dimethylbiguanide hydrochloride) is a well-known AMPK activator and has been widely prescribed for type 2 diabetes mellitus (T2DM). Since the incidence of T2DM and dementia increases with aging, metformin has been considered to be one of the most promising drugs to target dementia and its related disorders. To that end, here, we tested the efficacy of metformin and HL271, a novel metformin derivative, in aging-induced cognitive decline. Water (control), metformin (100 mg/kg) or HL271 (50 mg/kg) were orally administered to aged mice for two months; then, the mice were subjected to behavioral tests to measure their cognitive function, particularly their contextual, spatial and working memory. AMPK phosphorylation was also measured in the drug-treated mouse brains. Our results show that oral treatment with HL271 (50 mg/kg) but not metformin (100 mg/kg) improved cognitive decline in aged mice. AMPK activation was correlated with behavior recovery after aging-induced cognitive decline. Taken together, these results suggest that the newly synthesized AMPK activator, HL271, could be a potential therapeutic agent to treat age-related cognitive decline.
Adenosine Monophosphate ; Aging ; Alzheimer Disease ; AMP-Activated Protein Kinases ; Animals ; Behavior Rating Scale ; Brain ; Cognition ; Cognition Disorders ; Dementia ; Diabetes Mellitus ; Diabetes Mellitus, Type 2 ; Energy Metabolism ; Incidence ; Memory, Short-Term ; Metformin ; Mice ; Phosphorylation ; Protein Kinases ; Public Health ; Water