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Autophagy Aug 2023Macroautophagy/autophagy is an important process responsible for protein turnover and cell survival in amino acid-deprived conditions, especially for leucine (Leu). With...
Macroautophagy/autophagy is an important process responsible for protein turnover and cell survival in amino acid-deprived conditions, especially for leucine (Leu). With the dramatic advances in mass spectrometry, many new post-translational modifications (PTMs) have been identified. However, whether these PTMs regulate autophagy remains unclear. Here we found global lysine crotonylation levels are significantly upregulated during Leu deprivation-induced autophagy. A comprehensive crotonylome profiling showed that YWHA/14-3-3 proteins are significantly enriched in the Leu regulated-crotonylome. The inhibition of YWHAE/14-3-3ε crotonylation by mutating two crotonylated sites to arginine, K73R K78R, significantly attenuates autophagy induced by Leu deprivation. Molecular dynamics suggest that YWHAE K73 and K78 crotonylations decrease protein conformation and thermodynamic stability. Moreover, we found crotonylation of YWHAE releases PPM1B to dephosphorylate ULK1 and consequently activate autophagy. Decrotonylation of YWHAE is mediated by HDAC7 whose activity is inhibited significantly by Leu deprivation. Taken together, our finding reveals a critical role of YWHAE crotonylation in Leu deprivation-induced autophagy.
Topics: Leucine; 14-3-3 Proteins; Autophagy; Mass Spectrometry; Protein Processing, Post-Translational
PubMed: 36628438
DOI: 10.1080/15548627.2023.2166276 -
Molecular Neurobiology Nov 2023The non-receptor protein tyrosine phosphatase is a class of enzymes that catalyze the dephosphorylation of phosphotyrosines in protein molecules. They are involved in... (Review)
Review
The non-receptor protein tyrosine phosphatase is a class of enzymes that catalyze the dephosphorylation of phosphotyrosines in protein molecules. They are involved in cellular signaling by regulating the phosphorylation status of a variety of receptors and signaling molecules within the cell, thereby influencing cellular physiological and pathological processes. In this article, we detail multiple non-receptor tyrosine phosphatase and non-receptor tyrosine phosphatase genes involved in the pathological process of brain disease. These include PTPN6, PTPN11, and PTPN13, which are involved in glioma signaling; PTPN1, PTPN5, and PTPN13, which are involved in the pathogenesis of Alzheimer's disease Tau protein lesions, PTPN23, which may be involved in the pathogenesis of Epilepsy and PTPN1, which is involved in the pathogenesis of Parkinson's disease. The role of mitochondrial tyrosine phosphatase in brain diseases was also discussed. Non-receptor tyrosine phosphatases have great potential for targeted therapies in brain diseases and are highly promising research areas.
Topics: Humans; Protein Tyrosine Phosphatases, Non-Receptor; Signal Transduction; Phosphorylation; Alzheimer Disease; Brain; Tyrosine
PubMed: 37458988
DOI: 10.1007/s12035-023-03487-5 -
Scientific Reports Jul 2023γ-Glutamylcyclotransferase (GGCT) is highly expressed in multiple types of cancer tissues and its knockdown suppresses the growth of cancer cells in vitro and in vivo....
γ-Glutamylcyclotransferase (GGCT) is highly expressed in multiple types of cancer tissues and its knockdown suppresses the growth of cancer cells in vitro and in vivo. Although GGCT is a promising target for cancer therapy, the mechanisms underlying the antitumor effects remain unclear. The knockdown of GGCT inhibited the MEK-ERK pathway, and activated the tumor suppressor retinoblastoma gene (RB) at the protein level in cancer cell lines. c-Met was down-regulated by the knockdown of GGCT in cancer cells and its overexpression attenuated the dephosphorylation of RB and cell cycle arrest induced by the knockdown of GGCT in lung cancer A549 cells. STAT3 is a transcription factor that induces c-Met expression. STAT3 phosphorylation and its nuclear expression level were decreased in GGCT-depleted A549 and prostate cancer PC3 cells. The simultaneous knockdown of AMPK and GGCT restored the down-regulated expression of c-Met, and attenuated the dephosphorylation of STAT3 and MEK-ERK-RB induced by the knockdown of GGCT in PC3 cells. An intraperitoneal injection of a GGCT inhibitor decreased c-Met protein expression in a mouse xenograft model of PC3 cells. These results suggest that the knockdown of GGCT activates the RB protein by inhibiting the STAT3-c-Met-MEK-ERK pathway via AMPK activation.
Topics: Humans; Male; Animals; Mice; AMP-Activated Protein Kinases; gamma-Glutamylcyclotransferase; Prostatic Neoplasms; Retinoblastoma; Disease Models, Animal; Retinal Neoplasms
PubMed: 37488242
DOI: 10.1038/s41598-023-39093-7 -
Heart Failure Reviews Jul 2024Heart failure (HF) can be caused by a variety of causes characterized by abnormal myocardial systole and diastole. Ca current through the L-type calcium channel (LTCC)... (Review)
Review
Heart failure (HF) can be caused by a variety of causes characterized by abnormal myocardial systole and diastole. Ca current through the L-type calcium channel (LTCC) on the membrane is the initial trigger signal for a cardiac cycle. Declined systole and diastole in HF are associated with dysfunction of myocardial Ca function. This disorder can be correlated with unbalanced levels of phosphorylation / dephosphorylation of LTCC, endoplasmic reticulum (ER), and myofilament. Kinase and phosphatase activity changes along with HF progress, resulting in phased changes in the degree of phosphorylation / dephosphorylation. It is important to realize the phosphorylation / dephosphorylation differences between a normal and a failing heart. This review focuses on phosphorylation / dephosphorylation changes in the progression of HF and summarizes the effects of phosphorylation / dephosphorylation of LTCC, ER function, and myofilament function in normal conditions and HF based on previous experiments and clinical research. Also, we summarize current therapeutic methods based on abnormal phosphorylation / dephosphorylation and clarify potential therapeutic directions.
Topics: Humans; Heart Failure; Phosphorylation; Calcium; Calcium Channels, L-Type; Endoplasmic Reticulum; Myocardium; Myofibrils
PubMed: 38498262
DOI: 10.1007/s10741-024-10395-w -
The FEBS Journal Oct 2023RAF activation is a key step for signalling through the mitogen-activated protein kinase (MAPK) pathway. The SHOC2 protein, along with MRAS and PP1C, forms a high... (Review)
Review
RAF activation is a key step for signalling through the mitogen-activated protein kinase (MAPK) pathway. The SHOC2 protein, along with MRAS and PP1C, forms a high affinity, heterotrimeric holoenzyme that activates RAF kinases by dephosphorylating a specific phosphoserine. Recently, our research, along with that of three other teams, has uncovered valuable structural and functional insights into the SHOC2-MRAS-PP1C (SMP) holoenzyme complex. In this structural snapshot, we review SMP complex assembly, the dependency on the bound-nucleotide state of MRAS, the substitution of MRAS by the canonical RAS proteins and the roles of SHOC2 and MRAS on PP1C activity and specificity. Furthermore, we discuss the effect of several RASopathy mutations identified within the SMP complex and explore potential therapeutic approaches for targeting the SMP complex in RAS/RAF-driven cancers and RASopathies.
Topics: MAP Kinase Signaling System; Mitogen-Activated Protein Kinases; Signal Transduction; ras Proteins; Holoenzymes
PubMed: 37074066
DOI: 10.1111/febs.16800 -
Biological Psychiatry Mar 2024LHPP was recently shown to be a risk gene for major depressive disorder. LHPP has been proven to dephosphorylate the residues of histidine, serine, threonine, and...
BACKGROUND
LHPP was recently shown to be a risk gene for major depressive disorder. LHPP has been proven to dephosphorylate the residues of histidine, serine, threonine, and tyrosine. However, much remains unknown about how LHPP contributes to depression.
METHODS
In the current study, we addressed this issue by integrating approaches of genetics, molecular biology, behavioral testing, and electrophysiology.
RESULTS
We found that levels of LHPP were upregulated in glutamatergic neurons of the ventral hippocampus in mice that displayed stress-induced depression-like behaviors. Knockout of LHPP in glutamatergic neurons of the brain improved the spontaneous activity of LHPP·CaMKIIαCre+ (conditional knockout) mice. Adeno-associated virus-mediated LHPP knockdown in the ventral hippocampus enhanced resistance against chronic social defeat stress in mice. Manipulations of LHPP levels impacted the density of dendritic spines and excitability of CA1 pyramidal neurons by mediating the expressions of BDNF (brain-derived neurotrophic factor) and PSD95 via the modulation of the dephosphorylation of CaMKIIα and ERK. Notably, compared with wild-type LHPP, human mutant LHPP (E56K, S57L) significantly increased the activity of the CaMKIIα/ERK-BDNF/PSD95 signaling pathway. Finally, esketamine, not fluoxetine, markedly alleviated the LHPP upregulation-induced depression-like behaviors.
CONCLUSIONS
These findings provide evidence that LHPP contributes to the pathogenesis of depression via threonine and serine hydrolases, thereby identifying LHPP as a potential therapeutic target in treating patients with major depressive disorder.
Topics: Humans; Mice; Animals; Brain-Derived Neurotrophic Factor; Depression; Depressive Disorder, Major; Mice, Knockout; Hippocampus; Neurons; Serine; Threonine; Stress, Psychological
PubMed: 37678540
DOI: 10.1016/j.biopsych.2023.08.026 -
Journal of Experimental & Clinical... Dec 2023With the advancements in bioinformatic technology, an increasing number of circular RNAs (circRNAs) have been discovered and their crucial roles in the development and...
BACKGROUND
With the advancements in bioinformatic technology, an increasing number of circular RNAs (circRNAs) have been discovered and their crucial roles in the development and progression of various malignancies have been confirmed through multiple pathways. However, the specific mechanisms involving protein-binding circRNAs in colorectal cancer (CRC) remain largely unexplored.
METHODS
Differential circRNA expression was assessed using a human circRNA microarray in five CRC tissue and paired normal samples. CircGPRC5A expression was then confirmed in the CRC tissues and paired normal samples using qRT-PCR. The biological function of circGPRC5A in CRC were studied in vitro and in vivo. Western blotting, fluorescence in situ hybridization, immunofluorescence, RNA pulldown, mass spectrometry, immunoprecipitation, quantitative phosphoproteomics, and RNA-binding protein immunoprecipitation assays were used to study circGPRC5A.
RESULTS
Our analysis revealed that circGPRC5A expression was higher in CRC tissues compared to normal tissues and was associated with tumor size, tumor stage and lymph node status. CircGPRC5A promoted CRC cell proliferation, migration, and metastasis in vitro and in vivo. CircGPRC5A could stabilize PPP1CA protein by inhibiting the binding between UBA1 and PPP1CA, and increasing YAP dephosphorylation.
CONCLUSIONS
Our study revealed that circGPRC5A plays an essential function in CRC progression by stabilizing PPP1CA protein and enhancing YAP dephosphorylation. CircGPRC5A could act as a novel and potential target for CRC.
Topics: Humans; Cell Proliferation; Colorectal Neoplasms; Gene Expression Regulation, Neoplastic; In Situ Hybridization, Fluorescence; MicroRNAs; Protein Phosphatase 1; RNA; RNA, Circular
PubMed: 38057879
DOI: 10.1186/s13046-023-02915-7 -
A noncanonical function of SKP1 regulates the switch between autophagy and unconventional secretion.Science Advances Oct 2023Intracellular degradation of proteins and organelles by the autophagy-lysosome system is essential for cellular quality control and energy homeostasis. Besides...
Intracellular degradation of proteins and organelles by the autophagy-lysosome system is essential for cellular quality control and energy homeostasis. Besides degradation, endolysosomal organelles can fuse with the plasma membrane and contribute to unconventional secretion. Here, we identify a function for mammalian SKP1 in endolysosomes that is independent of its established role as an essential component of the family of SCF/CRL1 ubiquitin ligases. We found that, under nutrient-poor conditions, SKP1 is phosphorylated on Thr, allowing its interaction with V subunits of the vacuolar ATPase (V-ATPase). This event, in turn, promotes V-ATPase assembly to acidify late endosomes and enhance endolysosomal degradation. Under nutrient-rich conditions, SUMOylation of phosphorylated SKP1 allows its binding to and dephosphorylation by the PPM1B phosphatase. Dephosphorylated SKP1 interacts with SEC22B to promote unconventional secretion of the content of less acidified hybrid endosomal/autophagic compartments. Collectively, our study implicates SKP1 phosphorylation as a switch between autophagy and unconventional secretion in a manner dependent on cellular nutrient status.
Topics: Autophagy; Cell Membrane; Endosomes; Lysosomes; Vacuolar Proton-Translocating ATPases; Humans
PubMed: 37831778
DOI: 10.1126/sciadv.adh1134 -
International Journal of Biological... 2023Golgi-protein 73 (GP73) is highly expressed in hepatocellular carcinoma (HCC) and, as a secretory protein, it has been proposed as a serum biomarker indicating...
Golgi-protein 73 (GP73) is highly expressed in hepatocellular carcinoma (HCC) and, as a secretory protein, it has been proposed as a serum biomarker indicating progression of HCC. The underlying mechanism by which GP73 may promote HCC metastasis is still poorly understood. In this study, we discovered that GP73 interacted with vimentin to facilitate Serine/Threonine-protein phosphatase PP1-alpha (PP1A)-mediated dephosphorylation of vimentin at S56 and facilitated vimentin polymerization, which blocked vimentin degradation via TRIM56-mediated ubiquitin/proteasome-dependent pathway. Strikingly, Clomipramine, a 5-hydroxytryptamine receptor (5-HTR) agonist approved for the treatment of depression, impaired GP73-mediated vimentin polymerization to effectively inhibit metastasis of HCC with high GP73 expression, which provided a new strategy against HCC metastasis. Lastly, it was found that serum GP73 (sGP73) correlated positively with vimentin in primary tissues of HCC, suggesting that sGP73 might serve as a potential serum biomarker for companion diagnosis of HCC with highly expressed vimentin. In summary, this study reveals the process of GP73-mediated vimentin polymerization and proves that Clomipramine serves as a potential drug targeting vimentin for metastatic HCC patients with high sGP73 level.
PubMed: 37564210
DOI: 10.7150/ijbs.85431 -
The Journal of Clinical Investigation Nov 2023Consumption of low dietary potassium, common with ultraprocessed foods, activates the thiazide-sensitive sodium chloride cotransporter (NCC) via the with no (K) lysine...
Consumption of low dietary potassium, common with ultraprocessed foods, activates the thiazide-sensitive sodium chloride cotransporter (NCC) via the with no (K) lysine kinase/STE20/SPS1-related proline-alanine-rich protein kinase (WNK/SPAK) pathway to induce salt retention and elevate blood pressure (BP). However, it remains unclear how high-potassium "DASH-like" diets (dietary approaches to stop hypertension) inactivate the cotransporter and whether this decreases BP. A transcriptomics screen identified Ppp1Ca, encoding PP1A, as a potassium-upregulated gene, and its negative regulator Ppp1r1a, as a potassium-suppressed gene in the kidney. PP1A directly binds to and dephosphorylates NCC when extracellular potassium is elevated. Using mice genetically engineered to constitutively activate the NCC-regulatory kinase SPAK and thereby eliminate the effects of the WNK/SPAK kinase cascade, we confirmed that PP1A dephosphorylated NCC directly in a potassium-regulated manner. Prior adaptation to a high-potassium diet was required to maximally dephosphorylate NCC and lower BP in constitutively active SPAK mice, and this was associated with potassium-dependent suppression of Ppp1r1a and dephosphorylation of its cognate protein, inhibitory subunit 1 (I1). In conclusion, potassium-dependent activation of PP1A and inhibition of I1 drove NCC dephosphorylation, providing a mechanism to explain how high dietary K+ lowers BP. Shifting signaling of PP1A in favor of activation of WNK/SPAK may provide an improved therapeutic approach for treating salt-sensitive hypertension.
Topics: Animals; Mice; Blood Pressure; Solute Carrier Family 12, Member 3; Protein Serine-Threonine Kinases; Sodium Chloride; Potassium, Dietary; Kidney; Hypertension; Potassium; Phosphorylation
PubMed: 37676724
DOI: 10.1172/JCI158498