Pleckstrin Homology-like Domain, Family A, Member 1 Research Articles

PHLDA1 contributes to hypoxic ischemic brain injury in neonatal rats via inhibiting FUNDC1-mediated mitophagy.

Hypoxia-ischemia (HI) is one of the main causes of neonatal brain injury. Mitophagy has been implicated in the degradation of damaged mitochondria and cell survival following neonatal brain HI injury. Pleckstrin homology-like domain family A member 1 (PHLDA1) plays vital roles in the progression of various disorders including the regulation of oxidative stress, the immune responses and apoptosis. In the present study we investigated the role of PHLDA1 in HI-induced neuronal injury and further explored the mechanisms underlying PHLDA1-regulated mitophagy in vivo and in vitro. HI model was established in newborn rats by ligation of the left common carotid artery plus exposure to an oxygen-deficient chamber with 8% O2 and 92% N2. In vitro studies were conducted in primary hippocampal neurons subjected to oxygen and glucose deprivation/-reoxygenation (OGD/R). We showed that the expression of PHLDA1 was significantly upregulated in the hippocampus of HI newborn rats and in OGD/R-treated primary neurons. Knockdown of PHLDA1 in neonatal rats via lentiviral vector not only significantly ameliorated HI-induced hippocampal neuronal injury but also markedly improved long-term cognitive function outcomes, whereas overexpression of PHLDA1 in neonatal rats via lentiviral vector aggravated these outcomes. PHLDA1 knockdown in primary neurons significantly reversed the reduction of cell viability and increase in intracellular reactive oxygen species (ROS) levels, and attenuated OGD-induced mitochondrial dysfunction, whereas overexpression of PHLDA1 decreased these parameters. In OGD/R-treated primary hippocampal neurons, we revealed that PHLDA1 knockdown enhanced mitophagy by activating FUNDC1, which was abolished by FUNDC1 knockdown or pretreatment with mitophagy inhibitor Mdivi-1 (25 μM). Notably, pretreatment with Mdivi-1 or the knockdown of FUNDC1 not only increased brain infarct volume, but also abolished the neuroprotective effect of PHLDA1 knockdown in HI newborn rats. Together, these results demonstrate that PHLDA1 contributes to neonatal HI-induced brain injury via inhibition of FUNDC1-mediated neuronal mitophagy.

Silencing of the PHLDA1 leads to global proteome changes and differentiation pathways of human neuroblastoma cells.

Neuroblastoma (NB) is the most common extracranial pediatric solid tumor originating from the abnormal development of cells of the sympathoadrenal lineage of the neural crest. Targeting GD2 ganglioside (GD2), a glycolipid expressed on neuroblastoma cells, with GD2 ganglioside-recognizing antibodies affects several pivotal signaling routes that drive or influence the malignant phenotype of the cells. Previously performed gene expression profiling helped us to identify the PHLDA1 (pleckstrin homology-like domain family A member 1) gene as the most upregulated gene in the IMR-32 human neuroblastoma cells treated with the mouse 14G2a monoclonal antibody. Mass spectrometry-based proteomic analyses were applied to better characterize a role of PHLDA1 protein in the response of neuroblastoma cells to chimeric ch14.18/CHO antibody. Additionally, global protein expression profile analysis in the IMR-32 cell line with PHLDA1 silencing revealed the increase in biological functions of mitochondria, accompanied by differentiation-like phenotype of the cells. Moreover, mass spectrometry analysis of the proteins co-immunoprecipitated using anti-PHLDA1-specific antibody, selected a group of possible PHLDA1 binding partners. Also, a more detailed analysis suggested that PHLDA1 interacts with the DCAF7/AUTS2 complex, a key component of neuronal differentiation in vitro. Importantly, our results indicate that PHLDA1 silencing enhances the EGF receptor signaling pathway and combinatory treatment of gefitinib and ch14.18/CHO antibodies might be beneficial for neuroblastoma patients. Data are available via ProteomeXchange with the identifier PXD044319.

Knockdown of PHLDA1 alleviates sepsis-induced acute lung injury by downregulating NLRP3 inflammasome activation.

To investigate the regulatory mechanism of pleckstrin homology-like domain, family A, member 1 (PHLDA1) in sepsis-induced acute lung injury (ALI). Mice model of sepsis were established by cecal ligation and puncture (CLP). The expression of PHLDA1 was reduced by injecting short hairpin RNA (shRNA)-PHLDA1 into the tail vein. The levels of PHLDA1, pro-inflammatory cytokines, such as interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), IL-1β, IL-18, super-oxide dismutase (SOD), malondialdehyde (MDA), and glutathione (GSH), molecular mechanism related to pyroptosis, such as caspase 1, adaptor apoptosis-associated speck-like protein containing a CARD (ASC), and gasdermin D (GSDMD)-N, and nucleotide oligomerization domain (NOD)-like receptor family pyrin domain-containing 3 (NLRP3) were tested by Western blot analysis, quantitative real-time polymerase chain reaction, and enzyme-linked-immunosorbent serologic assay. Pathological changes in lung tissues were examined by hematoxylin and eosin staining. Wet-dry weight ratio of lung tissues was observed. The expression of PHLDA1 was up-regulated in lung tissues from CLP-induced septic mice. Knockdown of PHLDA1 could reduce lung injury and wet-dry weight ratio in mice with sepsis-induced ALI. Moreover, silencing of PHLDA1 decreased the expressions of IL-1β, TNF-α, IL-18, IL-6, and MDA but increased SOD and GSH expressions in CLP-induced septic mice. The expressions of NLRP3, GSDMD-N, ASC, and caspase 1 were decreased by PHLDA1 silencing. Knockdown of PHLDA1 inhibited lung inflammation and pyroptosis in mice with sepsis-induced ALI by down-regulating NLRP3.

HDAC Inhibition Restores Response to HER2-Targeted Therapy in Breast Cancer via PHLDA1 Induction.

The downregulation of Pleckstrin Homology-Like Domain family A member 1 (PHLDA1) expression mediates resistance to targeted therapies in receptor tyrosine kinase-driven cancers. The restoration and maintenance of PHLDA1 levels in cancer cells thus constitutes a potential strategy to circumvent resistance to inhibitors of receptor tyrosine kinases. Through a pharmacological approach, we identify the inhibition of MAPK signalling as a crucial step in PHLDA1 downregulation. Further ChIP-qPCR analysis revealed that MEK1/2 inhibition produces significant epigenetic changes at the PHLDA1 locus, specifically a decrease in the activatory marks H3Kme3 and H3K27ac. In line with this, we show that treatment with the clinically relevant class I histone deacetylase (HDAC) inhibitor 4SC-202 restores PHLDA1 expression in lapatinib-resistant human epidermal growth factor receptor-2 (HER2)+ breast cancer cells. Critically, we show that when given in combination, 4SC-202 and lapatinib exert synergistic effects on 2D cell proliferation and colony formation capacity. We therefore propose that co-treatment with 4SC-202 may prolong the clinical efficacy of lapatinib in HER2+ breast cancer patients.

Protective effect of basic helix-loop-helix family member e40 on cerebral ischemia/reperfusion injury: Inhibition of apoptosis via repressing the transcription of pleckstrin homology-like domain family A, member 1.

During ischemic stroke treatment, cerebral ischemia/reperfusion (I/R) injury results in neuronal cell death and neurological dysfunctions in brain. Previous studies indicate that basic helix-loop-helix family member e40 (BHLHE40) exerts protective effects on the pathology of neurogenic diseases. However, the protective function of BHLHE40 in I/R is unclear. This study aimed to explore the expression, role and potential mechanism of BHLHE40 after ischemia. We established models of I/R injury in rats and of oxygen-glucose deprivation/reoxygenation (OGD/R) in primary hippocampal neurons. Nissl and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining was performed to detect neuronal injury and apoptosis. Immunofluorescence was used to detect BHLHE40 expression. Cell viability and cell damage measurements were conducted using Cell Counting Kit-8 (CCK-8) assay and lactate dehydrogenase (LDH) assay. The regulation of BHLHE40 to pleckstrin homology-like domain family A, member 1 (PHLDA1) was assessed using the dual-luciferase assay and chromatin immunoprecipitation (ChIP) assay. Cerebral I/R rats exhibited severe neuronal loss and apoptosis in hippocampal cornu Ammonis 1 (CA1) region, accompanied by downregulated BHLHE40 expression at both mRNA and protein levels, indicating that BHLHE40 may regulate the apoptosis of hippocampal neurons. The function of BHLHE40 in neuronal apoptosis during cerebral I/R was further explored by establishing an OGD/R model in vitro. Low expression of BHLHE40 was also observed in neurons treated with OGD/R. The OGD/R administration inhibited cell viability and enhanced cell apoptosis in hippocampal neurons, whereas BHLHE40 overexpression reversed those changes. Mechanistically, we demonstrated that BHLHE40 could repress PHLDA1 transcription by binding to PHLDA1 promoter. The PHLDA1 is a facilitator of neuronal damage in brain I/R injury and its upregulation reversed the effects caused by BHLHE40 overexpression in vitro. The transcription factor BHLHE40 may protect against brain I/R injury through repressing cell damage via regulating PHLDA1 transcription. Thus, BHLHE40 may be a candidate gene for further study of molecular or therapeutic targets for I/R.

PHLDA1 modulates microglial response and NLRP3 inflammasome signaling following experimental subarachnoid hemorrhage.

Balancing microglia M1/M2 polarization is an effective therapeutic strategy for neuroinflammation after subarachnoid hemorrhage (SAH). Pleckstrin homology-like domain family A member 1 (PHLDA1) has been demonstrated to play a crucial role in immune response. However, the function roles of PHLDA1 in neuroinflammation and microglial polarization after SAH remain unclear. In this study, SAH mouse models were assigned to treat with scramble or PHLDA1 small interfering RNAs (siRNAs). We observed that PHLDA1 was significantly increased and mainly distributed in microglia after SAH. Concomitant with PHLDA1 activation, nod-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasome expression in microglia was also evidently enhanced after SAH. In addition, PHLDA1 siRNA treatment significantly reduced microglia-mediated neuroinflammation by inhibiting M1 microglia and promoting M2 microglia polarization. Meanwhile, PHLDA1 deficiency reduced neuronal apoptosis and improved neurological outcomes after SAH. Further investigation revealed that PHLDA1 blockade suppressed the NLRP3 inflammasome signaling after SAH. In contrast, NLRP3 inflammasome activator nigericin abated the beneficial effects of PHLDA1 deficiency against SAH by promoting microglial polarization to M1 phenotype. In all, we proposed that PHLDA1 blockade might ameliorate SAH-induced brain injury by balancing microglia M1/M2 polarization via suppression of NLRP3 inflammasome signaling. Targeting PHLDA1 might be a feasible strategy for treating SAH.

PHLDA1 knockdown alleviates mitochondrial dysfunction and endoplasmic reticulum stress-induced neuronal apoptosis via activating PPARγ in cerebral ischemia-reperfusion injury

Mitochondrial dysfunction and endoplasmic reticulum (ER) stress occur in ischemic stroke. The disruption of these two organelles can directly lead to cell death through various signaling pathways. Thus, investigation of the associated molecular mechanisms in cerebral ischemia is a prerequisite for stroke treatment. Pleckstrin homology-like domain family A member 1 (PHLDA1) is a multifunctional protein that can modulate mitochondrial function and ER stress in cardiomyocyte and cancer cells. This work studied the role of PHLDA1 in cerebral ischemic/reperfusion (I/R) injury and explored the underlying mechanisms associated with mitochondrial functions and ER stress. Middle cerebral artery occlusion/reperfusion (MCAO/R)-treated mice and oxygen-glucose deprivation/reoxygenation (OGD/R)-stimulated neurons were used as I/R models in vivo and in vitro, respectively. PHLDA1 was upregulated in ischemic penumbra of MCAO/R-induced mice and OGD/R-exposed neurons. In vitro, PHLDA1 knockdown protected neurons from OGD/R-induced apoptosis. In vivo, PHLDA1 silencing facilitated functional recovery and reduced cerebral infarct volume. Mechanistically, PHLDA1 knockdown promoted PPARγ nuclear translocation, which may mediate the effects on reversion of mitochondrial functions and alleviation of ER stress. In summary, PHLDA1 knockdown alleviates neuronal ischemic injuries in mice. PPARγ activation and mitochondrial dysfunction and endoplasmic reticulum stress attenuation are involved in the underlying mechanisms.

Pleckstrin Homology-Like Domain, Family A, Member 1 (PHLDA1): A Multifaceted Cell Survival Factor that Drives Metabolic Disease

Pleckstrin homology-like domain, family A, member 1 (PHLDA1) is a multifaceted intracellular protein belonging to the evolutionarily conserved pleckstrin homology-related domain family. Its murine homologue, T-cell death-associated 51 (TDAG51) gene, was initially discovered for its role in activation-induced apoptosis in T-cell hybridomas. In recent years, PHLDA1 has received increased attention due to its association with obesity, fatty liver disease, diabetes, atherosclerosis, and cancer. Accumulating evidence also supports its role in endoplasmic reticulum stress signaling pathways as a crucial mediator of apoptosis, autophagy, and cell proliferation. In this review, the current knowledge of PHLDA1 gene and protein regulation, localization, and function is summarized. This review highlights the pro- and anti-apoptotic roles of PHLDA1 that contribute to vast array of metabolic diseases.

Knockdown of PHLDA1 Alleviates Necrotizing Enterocolitis by Inhibiting NLRP3 Inflammasome Activation and Pyroptosis Through Enhancing Nrf2 Signaling

ABSTRACT Objective Pleckstrin homology-like domain family A member 1 (PHLDA1) is involved in the progression of intestine-related diseases, but its role and related mechanisms in Necrotizing enterocolitis (NEC) are unclear. The aim of this study was to better understand the function of PHLDA1 in NEC and the underlying mechanisms. Methods A neonatal mouse model of NEC was established by hypoxic hypothermia, and sh-PHLDA1 was transfected into mice to observe the mortality of each group within 4 days. The levels of IL-1β, IL-6, IL-18 and TNF-α were measured by PCR and ELISA. ROS, MDA, SOD, and GSH-Px levels were detected by Dihydroethidium (DHE) method and kit; expression of pyroptosis-related factors including NLRP3, ASC, cleaved-caspase1, GSDMD-N, IL-1β, IL-18, and Nrf2 were detected by western-blot; mechanistically, the effects of transfection of sh-PHLDA1 and ML385 (Nrf2 inhibitor) were investigated, and the expression of pyroptosis-related factors was detected again. Results PHLDA1 was highly expressed in the intestinal tissues of NEC mice, and transfection of sh-PHLDA1 improved the survival rate, alleviated intestinal lesions, improved intestinal inflammation, oxidative stress and cellular scorching in NEC. In addition, sh-PHLDA1 was able to inhibit NLRP3 activation and pyroptosis by activating Nrf2. Conclusion Knockdown of PHLDA1 attenuated necrotizing small intestinal colitis by enhancing Nrf2 expression to inhibit NLRP3 inflammasome activation and pyroptosis.

PHLDA1 knockdown inhibits inflammation and oxidative stress by regulating JNK/ERK pathway, and plays a protective role in sepsis-induced acute kidney injury

Acute kidney injury (AKI), a prevalent complication of sepsis, causes substantial burden on patients' families as well as the society. More reliable markers are urgently required for the prevention and treatment of AKI. Pleckstrin homology-like domain, family A, member 1 (PHLDA1) was implicated in various diseases, but its involvement in sepsis-induced AKI remains to be explored. The JNK/ERK pathway has been revealed as being involved in progression of sepsis. One previous study demonstrated that PHLDA1 could activate the JNK/ERK pathway in hepatic ischemia/reperfusion injury. Nevertheless, involvement of PHLDA1 in sepsis-triggered AKI through the JNK/ERK pathway has not been probed. A cecal ligation and punctured (CLP) mice model of sepsis-induced AKI was established. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and immunofluorescence staining were applied to evaluate the expression of PHLDA1. Concentration of blood urea nitrogen (BUN) and serum creatinine (Scr), inflammation markers, including interleukin-6 (IL-6), IL-1β, and tumor necrosis factor-α, as well as oxidative stress-associated proteins (catalase, malondialdehyde, superoxide dismutase, and glutathione), in the kidney tissues of mice were evaluated by enzyme-linked-immunosorbent serologic assay. Western blot analysis was applied for measuring protein expression levels. The BUN and SCr levels in mice were obviously elevated in the CLP group compared to the sham group. Moreover, the expression of PHLDA1 was also elevated in the CLP group in comparison to the sham group. Down-regulation of PHLDA1 alleviated renal injury, inflammation, and oxidative stress in AKI model. Mechanistic study showed that PHLDA1 knockdown suppressed the activation of c-JUN N-terminal kinase/p38 and extracellular signal-regulated kinase (JNK/ERK) pathway. Down-regulation of PHLDA1 suppressed inflammation and oxidative stress through the modulation of JNK/ERK pathway in sepsis-induced AKI. The results could offer a novel insight into the treatment of patients with sepsis-induced AKI.

Research Progress of Pleckstrin Homology Like Domain Family A Member 1 in Tumor

Pleckstrin homology like domain family A member 1(PHLDA1) is also known as T-cell death-associated gene 51 (TDAG51).Studies have demonstrated that the abnormal expression of PHLDA1 is closely associated with the formation,development,and metastasis of tumors.We summarized the latest research advances in the structure and biological properties of PHLDA1,as well as the roles of PHLDA1 in multiple malignanttumors such as breast cancer,cancer,liver gastric cancer,liver cancer,melanoma,and osteosarcoma,aiming to comprehensively reveal the significance of PHLDA1 in the clinical diagnosis of tumors.

PHLDA1 promotes sevoflurane-induced pyroptosis of neuronal cells in developing rats through TRAF6-mediated activation of Rac1

Sevoflurane anesthesia induces neurocognitive impairment and pyroptosis in the developing brain. Pleckstrin homology-like domain, family A, member 1 (PHLDA1) was involved in neuronal apoptosis, oxidative stress and inflammation during ischemic stroke. The role of PHLDA1 in sevoflurane-induced pyroptosis in developing rats was investigated. Firstly, neonatal rats at day 7 was exposed to 2.0% sevoflurane for 6 h to induce neurotoxicity. Pathological analysis showed that sevoflurane anesthesia induced hippocampal injury and reduced the number of neurons. The expression of PHLDA1 was elevated in hippocampus of sevoflurane-treated rats. Secondly, sevoflurane anesthesia-treated neonatal rats were injected with adeno-associated virus serotype (AAV) to mediate knockdown of PHLDA1. Injection with AAV-shPHLDA1 ameliorated sevoflurane-induced hippocampal injury and neurocognitive impairment in rats. Moreover, knockdown of PHLDA1 increased the number of neurons in sevoflurane-treated rats. Silence of PHLDA1 suppressed neuronal apoptosis, and inhibited pyroptosis in sevoflurane-treated rats. Thirdly, PHLDA1 was also elevated in sevoflurane-treated primary neuronal cells. Loss of PHLDA1 also enhanced cell viability and suppressed pyroptosis of sevoflurane-treated primary neuronal cells. Lastly, silence of PHLDA1 reduced protein expression of TRAF6 and p-Rac1 in sevoflurane-treated rats and neuronal cells. Over-expression of TRAF6 attenuated PHLDA1 silence-induced increase of cell viability and decreased pyroptosis in neuronal cells. In conclusion, loss of PHLDA1 protected against sevoflurane-induced pyroptosis in developing rats through inhibition of TRAF6-mediated activation of Rac1.

PHLDA1 Suppresses TLR4-Triggered Proinflammatory Cytokine Production by Interaction With Tollip.

Pleckstrin homology-like domain, family A, member 1 (PHLDA1) has been reported to be expressed in many mammalian tissues and cells. However, the functions and exact mechanisms of PHLDA1 remain unclear. In this study, we found that PHLDA1 expression was significantly altered in macrophages after exposure to lipopolysaccharide (LPS) in vitro, suggesting that PHLDA1 may be involved in the regulation of TLR4 signaling pathway activated by LPS. PHLDA1 attenuated the production of LPS-stimulated proinflammatory cytokines (TNF-α, IL-6, and IL-1β). Further research showed that the phosphorylation levels of some important signal molecules in TLR4/MyD88-mediated MAPK and NF-κB signaling pathways were reduced by PHLDA1, which in turn impaired the transcription factors NF-κB and AP1 nuclear translocation and their responsive element activities. Furthermore, we found that PHLDA1 repressed LPS-induced proinflammatory cytokine production via binding to Tollip which restrained TLR4 signaling pathway. A mouse model of endotoxemia was established to confirm the above similar results. In brief, our findings demonstrate that PHLDA1 is a negative regulator of LPS-induced proinflammatory cytokine production by Tollip, suggesting that PHLDA1 plays an anti-inflammatory role through inhibiting the TLR4/MyD88 signaling pathway with the help of Tollip. PHLDA1 may be a novel therapeutic target in treating endotoxemia.

PHLDA1 Blockade Alleviates Cerebral Ischemia/Reperfusion Injury by Affecting Microglial M1/M2 Polarization and NLRP3 Inflammasome Activation

Cerebral ischemia/reperfusion injury is the main cause of neurological deficit following stroke. Pleckstrin homology-like domain, family A, member 1 (PHLDA1) is increasingly recognized as a critical determinant in immunological regulation and cell apoptosis, but its role in neuroinflammation during cerebral ischemia/reperfusion injury remains to be elucidated. In this study, middle cerebral artery occlusion/reperfusion (MCAO/R) in C57BL/6 mice and oxygen-glucose deprivation/reoxygenation (OGD/R) in BV-2 cells were used as models in vivo and in vitro, respectively. MACO/R mice and OGD/R cells were treated with scramble or PHLDA1 small interfering RNAs (siRNAs) to achieve the goal of PHLDA1 knockdown. The results showed that the expression of PHLDA1 was significantly increased in MCAO/R mice and OGD/R cells compared to their normal controls, respectively. Mice treated with PHLDA1 siRNA exhibited a lower degree of infarct volume and brain water content compared to the NC siRNA-treated mice. Notably, PHLDA1 knockdown switched the M1 pro-inflammatory phenotype to the M2 anti-inflammatory phenotype by decreasing the expression of M1 markers (i.e., CD16, TNF-α, IL-6 and IFN-γ, and iNOS) and elevating the expression of M2 markers (i.e., CD206, IL-4, IL-10, and Arg-1). Moreover, PHLDA1 knockdown suppressed the NLRP3 inflammasome activation by reducing NLRP3, ASC, cleaved caspase 1 and cleaved IL-1β expression. In summary, these results suggest that PHLDA1 blockade effectively alleviates the ischemia/reperfusion-induced cerebral injury by switching microglial M1/M2 polarization and inhibiting NLRP3 inflammasome activation. Targeting PHLDA1 could be considered as a novel strategy in the treatment against post-ischemic brain injury.

PHLDA1 expression in ulcerative colitis: A potential role in the management of dysplasia.

Pleckstrin homology-like domain, family A, member 1 (PHLDA1) is a protein involved in cell proliferation, adhesion and migration in colon cancer. In normal large intestinal mucosa, this protein is expressed only in the crypts. By contrast, its expression in adenomas and cancers of the large intestine is spread throughout the glandular ducts, and it has been reported that PHLDA1 may be involved in the process of carcinogenesis. PHLDA1 may also be involved in the pathogenesis of ulcerative colitis (UC). The expression levels of PHLDA1 in tissues from patients with UC were analyzed using immunohistochemistry, and its relationship with the development of UC-associated colorectal cancer (UC-CRC) was examined. Overall, tissue samples from 143 lesions (90 colitis lesions, 39 dysplastic lesions and 14 UC-CRC lesions) were prepared from excised specimens of 49 patients with UC who underwent surgery in Tokyo Medical and Dental University Hospital between January 2004 and December 2017. Subsequently, immunostaining for PHLDA1 was performed. PHLDA1 expression was evaluated in UC-CRC and dysplastic tissues within the entire lesion area on the slide and in colitis over the area of the accompanying duct. The cytoplasmic staining intensity was classified into four levels, and the expression score (0-2 points) was calculated. The median PHLDA1 expression score was 0.295 for colitis, 0.607 for dysplasia and 0.865 for UC-CRC. The dysplasia expression score was significantly higher than the colitis score (P<0.001), while the UC-CRC expression score was significantly higher than the dysplasia score (P=0.003). The expression levels of PHLDA1 in UC cases were higher in colitis, followed by dysplasia and UC-CRC, which suggested that this protein may be involved in the carcinogenesis of UC-CRC. In addition, PHLDA1 immunostaining may help in the diagnosis of dysplasia, which is a type of precancerous lesion.

Loss of PHLDA1 has a protective role in OGD/R-injured neurons via regulation of the GSK-3β/Nrf2 pathway.

Pleckstrin homology-like domain, family A, member 1 (PHLDA1) is a multifunctional protein that plays a role in diverse pathological conditions. However, whether PHLDA1 participates in cerebral ischemia-reperfusion injury has not been reported. The goals of the present work were to assess the possible relationship between PHLDA1 and cerebral ischemia-reperfusion injury. Hippocampal neurons were subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) to simulate cerebral ischemia-reperfusion injury in vitro, which led to significant increases in the expression of PHLDA1. Cellular functional studies showed that the knockdown of PHLDA1 produced a protective role in OGD/R-injured neurons via the down-regulation of neuronal apoptosis, oxidative stress and proinflammatory cytokine release. On the contrary, the overexpression of PHLDA1 rendered neurons more vulnerable to OGD/R injury. In-depth research revealed that the inhibition of PHLDA1 resulted in the enhancement of nuclear factor erythroid 2 like 2 (Nrf2) signaling in OGD/R-injured neurons. The reactivation of glycogen synthase kinase 3β (GSK-3β) abolished the PHLDA1-inhibition-mediated activation of Nrf2 signaling. Moreover, the restraint of Nrf2 signaling diminished the PHLDA1-knockdown-induced neuroprotective effects in OGD/R-injured neurons. In summary, the data of our work show that the loss of PHLDA1 protects against OGD/R injury via potentiating Nrf2 signaling via the regulation of GSK-3β. This work underscores a potential role of PHLDA1 in cerebral ischemia-reperfusion injury and proposes PHLDA1 as an attractive target for the development of neuroprotective therapy.

PHLDA1 Modulates the Endoplasmic Reticulum Stress Response and is required for Resistance to Oxidative Stress-induced Cell Death in Human Ovarian Cancer Cells.

Objective: Pleckstrin homology-like domain family A member 1 (PHLDA1) has been implicated in the regulation of apoptosis in a variety of normal cell types and cancers. However, its precise pathophysiological functions remain unclear. Here, we examined the expression of PHLDA1 in human ovarian cancer (OvCa), the most lethal gynecologic malignancy, and investigated its functions in vitro.Materials and Methods: The expression of PHLDA1 was detected by reverse-transcription quantitative PCR (RT-qPCR), immunohistochemical analysis, or western blotting, silencing of PHLDA was achieved by shRNA, cell proliferation was detected by MTT assay, apoptosis was detected by flow cytometric analysis, PHLDA1 transcriptional activity was detected by dual luciferase reporter assay.Results: PHLDA1 mRNA levels were significantly higher in serous OvCa specimens compared with normal ovarian tissue, confirmed by immunohistochemical staining of PHLDA1 protein, which also indicated the expression was predominantly cytoplasmic. Bioinformatics analysis of publicly available datasets indicated that PHLDA1 expression in clinical specimens was significantly associated with disease stage, progression-free survival, and overall survival. In human OvCa cell lines, shRNA-mediated silencing of PHLDA1 expression enhanced apoptosis after exposure to oxidative stress- and endoplasmic reticulum stress-inducing agents. PHLDA1 silencing increased not the expression of anti-apoptotic or autophagy-related proteins, but the expression of ER stress response-associated proteins.Conclusion: PHLDA1 modulates the susceptibility of human OvCa cells to apoptosis via the endoplasmic reticulum stress response pathway.

Circ0085539 Promotes Osteosarcoma Progression by Suppressing miR-526b-5p and PHLDA1 Axis.

Background: We have previously found that circ0085539/miR-526b-5p axis participated in the progression of osteosarcoma (OS). We have been interested in expanding the networking involving circ0085539 and miR-526-5p. We identified another critical downstream target of this axis, pleckstrin homology-like domain family A member 1 (PHLDA1), thus intending to uncover the interaction between the axis and PHLDA1.Methods: Live imaging of mice tumor xenografts was conducted. Immunohistochemistry (IHC) and H&E staining were performed for our in vivo experiment, while the CCK-8 assay, flow cytometry, wound healing, Transwell invasion, and clone formation were employed to assess cellular biological functions.Results: Circ0085539 was first found to be upregulated in osteosarcoma tissues and cell lines, and circ0085539 knockdown obviously suppressed proliferation and induced apoptosis. Subsequently, miR-526b-5p functionally attenuated the tumor suppressive effects induced by circ0106714 silencing on OS cells. PHLDA1 silencing significantly led to proliferation suppression, apoptosis induction, as well as the inhibition of migration, invasion, and colony formation capabilities in OS cells, which also could be restored by the miR-526b-5p inhibitor.Conclusion: Taken together, circ0085539 effectively promoted progression of osteosarcoma through sponging miR-526b-5p to release PHLDA1, strongly suggesting that in vivo intervention of circ0085539–miR-526b-5p–PHLDA1 axis could function as a promising OS-targeted therapy.

PHLDA1 promotes microglia-mediated neuroinflammation via regulating K63-linked ubiquitination of TRAF6

Microglia-mediated neuroinflammation plays an important role in the progression of neurodegenerative diseases including Parkinson's disease (PD). Pleckstrin homology-like domain family A member 1 (PHLDA1) plays an important role in immunological regulation, particularly in the Toll-like receptor-mediated immune response. Here, we explored the potential roles of PHLDA1 in microglia-mediated inflammation and neuronal protection. We found that PHLDA1 expression was rapidly increased in response to inflammatory stimuli in microglia cells in vivo or in vitro. Knockdown of PHLDA1 using adeno-associated virus serotype (AAV) ameliorated MPTP-induced motor deficits and inhibited neuroinflammation in mice. In support of this observation in vivo, we found that LPS-induced proinflammatory gene expression, including TNF-α, IL-1β, iNOS, and COX-2, was decreased in PHLDA1-deficient microglial cells. Mechanistic studies demonstrated that increased expression of PHLDA1, upon LPS stimulation in microglia, led to direct interaction with TRAF6 and enhanced its K63-linked ubiquitination-mediated NF-κB signaling activation. PHLDA1 deficiency interfered with TRAF6 K63-linked ubiquitination and inhibited microglial inflammatory responses. These findings reveal the first evidence that PHLDA1 is an important modulator of microglial function that is associated with microglia-mediated dopaminergic neurotoxicity. The data therefore provided the first evidence that PHLDA1 may be a potent modulator for neuroinflammation, and PHLDA1 may be a novel drug target for treatment of neuroinflammation-related diseases such as PD.

PHLDA1 is a new therapeutic target of oxidative stress and ischemia reperfusion-induced myocardial injury

AimOxidative stress plays an important role in myocardial ischemia-reperfusion injury. Pleckstrin homology-like domain, family A, member 1 (PHLDA1) was first identified in apoptosis induced by T cell receptor activation, and was shown to play a different role in different cell types and under different stimuli. The role and mechanism of PHLDA1 in oxidative stress-induced cardiomyocyte injury and cardiac ischemia-reperfusion were therefore determined. Main methodsCell viability and apoptotic rate were measured by Cell Counting Kit-8 and flow cytometry, respectively. Mitochondrial membrane potential was measured using JC-1 test kit. Reactive oxygen species (ROS) production was detected using ROS kit. HE staining was used to detect histological morphology, 2,3,5-triphenyltetrazolium chloride staining to detect infarct size, terminal deoxynucleotidyl transferase dUTP nick end labeling staining to detect the apoptotic rate, and immunohistochemistry and western blot analysis to detect protein expression. The binding of PHLDA1 to Bcl-2 associated X (Bax) was detected by immunoprecipitation. Key findingsThe results indicated that PHLDA1 is highly expressed in oxidative stress-induced cardiomyocyte and myocardial ischemia-reperfusion injuries. PHLDA1 overexpression in cardiomyocytes promoted oxidative stress-induced cardiomyocyte injury. At the same time, PHLDA1 knockdown improved oxidative stress-induced cardiomyocyte and myocardial ischemia-reperfusion injuries. In addition, PHLDA1 binds to Bax and the interaction is enhanced under H2O2 stimulation. SignificanceThe present results indicated that PHLDA1 interacts with Bax to participate in oxidative stress-induced cardiomyocyte injury and myocardial ischemia reperfusion injury.