PI3-kinase deletion promotes myelodysplasia by dysregulating autophagy in hematopoietic stem cells

The mechanism of lycopene alleviating cadmium-inhibited glucose uptake ability of epithelioma papulosum cyprini cells: miR-375, oxidative stress, and actin cytoskeleton dysfunction

Cadmium (Cd) poses a threat to fish and human health. Carp is the most widely farmed fish, and it is necessary to study the mechanism of Cd toxicity and effective mitigation methods for Cd poisoning in carps. We previously found that Cd up-regulated miR-375 in common carp spleens, and that IRS1, a factor involved in glucose (GLU) uptake, was a potential target gene of miR-375. However, whether Cd can decrease GLU uptake ability in fish remains unknown. Oxidative stress (OS) and actin cytoskeleton dysfunction (ACD) can take part in the mechanisms of GLU uptake ability reduction. Lycopene (Lyc) is a natural plant antioxidant, and epithelioma papulosum cyprini (EPC) cells are a model cell to study carps. Therefore, we conducted experiments with Cd or/and Lyc treatments to investigate the mechanisms of Lyc alleviating Cd-cytotoxicity on EPC cells from the perspectives of miR-375, OS, ACD, and GLU uptake ability. We found that Lyc mitigated Cd-caused miR-375 increase, OS, ACD, and GLU uptake ability reduction. Moreover, miR-375 overexpression/knockdown experiments demonstrated that miR-375 mediated OS, ACD, and GLU uptake ability reduction and targeted regulated IRS1-PI3K-AKT. Furthermore, NAC intervention experiment demonstrated that ROS mediated ACD and the reduction of GLU uptake via ROS/IRS1-PI3K-AKT. Taken together, Lyc alleviated Cd-decreased GLU uptake ability via miR-375-ROS/IRS1-PI3K-AKT and miR-375/IRS1-PI3K-AKT pathways in EPC cells. Our findings highlighted significant role of miR-375 in Cd-induced toxicity and elucidated the mechanism by which Lyc alleviated Cd-induced toxicity. Our study can provide new information and new targets for resisting environmental pollutant stress in animals.

Research progress on ferroptosis in Myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are a group of malignancies characterized by clonal proliferation of hematopoietic stem cells, ineffective hematopoiesis, peripheral cytopenias, and a high risk of transformation to acute myeloid leukemia. Current therapeutic strategies for MDS have limited efficacy. Thus, identifying new therapeutic targets and prognostic biomarkers is a critical future research direction. Ferroptosis, a new type of iron-dependent programmed cell death, has become a recent hotspot in the field of oncology research. Recent results have demonstrated that iron metabolism, lipid metabolism, and other pathways can be targeted to induce ferroptosis in MDS cells. In addition, ferroptosis-related genes are of significance in the prognosis and diagnosis of MDS. This article reviews the current research progress on ferroptosis in MDS, including its potential for targeting as a therapeutic intervention strategy.

Class I PI3Ks activate stretch-induced autophagy in trabecular meshwork cells

Elevated intraocular pressure (IOP) is the primary risk factor for glaucoma, a leading cause of irreversible blindness worldwide. IOP homeostasis is maintained through a balance between aqueous humor production and its drainage through the trabecular meshwork (TM)/Schlemm's Canal (SC) outflow pathway. Prior studies by our laboratory reported a key role of mechanical forces and primary cilia (PC)-dependent stretch-induced autophagy in IOP homeostasis. However, the precise mechanism regulating this process remains elusive. In this study, we investigated the upstream signaling pathway orchestrating autophagy activation during cyclic mechanical stretch (CMS) in primary cultured human TM cells, using biochemical and cell biological analyses. Our results indicate that TM cells express catalytic subunits of class IA PI3Ks (PIK3CA, B, and D), and that inhibition of class IA isoforms, but not class II and III, significantly prevent CMS-induced autophagy. Importantly, PIK3CA was found to localize in the PC. Furthermore, we identified a coordinated action of Class IA PI3Ks along INPP4A/B, a 4' inositol phosphatase, responsible for the formation of PI(3,4)P2 and PI(3)P and stretch-induced autophagy in TM cells. These findings contribute to a deeper understanding of the molecular mechanisms underlying IOP homeostasis.

Heat stress promotes osteogenic and odontogenic differentiation of stem cells from apical papilla via glucose-regulated protein 78-mediated autophagy

Background/purpose

Heat stress is essential for improving the efficacy of mesenchymal stem cell (MSC)-based regeneration medicine. However, it is still unclear whether and how heat stress influences the differentiation of stem cells from apical papilla (SCAPs). This research aimed to explore the potential mechanism of glucose-regulated protein 78 (GRP78) in regulating differentiation under heat stress in SCAPs.

Materials and methods

The proliferation ability was assessed using the 5-Ethynyl-2'- deoxyuridine (EdU) assay, cell counting kit assay (CCK-8), and flow cytometry (FCM). The osteogenic and odontogenic differentiation capacities were investigated through Western blot, quantitative reverse transcription polymerase chain reaction (qRT-PCR), alkaline phosphatase (ALP) staining and activity assay, alizarin red S (ARS) staining, as well as immunofluorescence staining. Western blot and transmission electron microscopy (TEM) were used to detect autophagy.

Results

Heat stress enhanced the osteogenic and odontogenic differentiation of SCAPs, but it did not significantly affect proliferation. Besides, GRP78 has been confirmed to modulate the differentiation induced by heat stress. Autophagy triggered by GRP78 enhanced osteogenic and odontogenic differentiation of SCAPs, while the knockdown of GRP78 or the inhibitor of autophagy suppressed the differentiation.

Conclusion

Heat stress induces osteogenic and odontogenic differentiation of SCAPs through GRP78-mediated autophagy.

The Crosstalk between Autophagy and Nrf2 Signaling in Cancer: from Biology to Clinical Applications

Autophagy is a catabolic process that has been conserved throughout evolution, serving to degrade and recycle cellular components and damaged organelles. Autophagy is activated under various stress conditions, such as nutrient deprivation, viral infections, and genotoxic stress, and operates in conjunction with other stress response pathways to mitigate oxidative damage and maintain cellular homeostasis. One such pathway is the Nrf2-Keap1-ARE signaling axis, which functions as an intrinsic antioxidant defense mechanism and has been implicated in cancer chemoprevention, tumor progression, and drug resistance. Recent research has identified a link between impaired autophagy, mediated by the autophagy receptor protein p62, and the activation of the Nrf2 pathway. Specifically, p62 facilitates Keap1 degradation through selective autophagy, leading to the translocation of Nrf2 into the nucleus, where it transcriptionally activates downstream antioxidant enzyme expression, thus safeguarding cells from oxidative stress. Furthermore, Nrf2 regulates p62 transcription, so a positive feedback loop involving p62, Keap1, and Nrf2 is established, which amplifies the protective effects on cells. This paper aims to provide a comprehensive review of the roles of Nrf2 and autophagy in cancer progression, the regulatory interactions between the Nrf2 pathway and autophagy, and the potential applications of the Nrf2-autophagy signaling axis in cancer therapy.

Characterization of stem cell landscape and assessing the stemness degree to aid clinical therapeutics in hematologic malignancies

Hematological malignancies are a group of cancers that affect the blood, bone marrow, and lymphatic system. Cancer stem cells (CSCs) are believed to be responsible for the initiation, progression, and relapse of hematological malignancies. However, identifying and targeting CSCs presents many challenges. We aimed to develop a stemness index (HSCsi) to identify and guide the therapy targeting CSCs in hematological malignancies. We developed a novel one-class logistic regression (OCLR) algorithm to identify transcriptomic feature sets related to stemness in hematologic malignancies. We used the HSCsi to measure the stemness degree of leukemia stem cells (LSCs) and correlate it with clinical outcomes.We analyze the correlation of HSCsi with genes and pathways involved in drug resistance and immune microenvironment of acute myeloid leukemia (AML). HSCsi revealed stemness-related biological mechanisms in hematologic malignancies and effectively identify LSCs. The index also predicted survival and relapse rates of various hematologic malignancies. We also identified potential drugs and interventions targeting cancer stem cells (CSCs) of hematologic malignancies by the index. Moreover, we found a correlation between stemness and bone marrow immune microenvironment in AML. Our study provides a novel method and tool to assess the stemness degree of hematologic malignancies and its implications for clinical outcomes and therapeutic strategies. Our HSC stemness index can facilitate the precise stratification of hematologic malignancies, suggest possible targeted and immunotherapy options, and guide the selection of patients.

Unraveling the Link between Class 1A PI3-Kinase, Autophagy, and Myelodysplasia

Myelodysplastic syndrome (MDS) is a clonal malignancy that develops from hematopoietic stem cells (HSCs), but the underlying mechanisms of MDS initiation are not well understood. The phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathway is often dysregulated in MDS. To investigate how PI3K inactivation affects HSC function, we generated a mouse model in which three Class IA PI3K genes were deleted in hematopoietic cells. Surprisingly, PI3K deficiency caused cytopenias, reduced survival, and multilineage dysplasia with chromosomal abnormalities, consistent with MDS initiation. PI3K-deficient HSCs had impaired autophagy, and pharmacologic treatment with autophagy-inducing reagents improved HSC differentiation. Furthermore, a similar autophagic degradation defect was observed in MDS patient HSCs. Therefore, our study uncovered a crucial protective role for Class IA PI3K in maintaining autophagic flux in HSCs to preserve the balance between self-renewal and differentiation.

Deciphering signaling pathways in hematopoietic stem cells: the molecular complexity of Myelodysplastic Syndromes (MDS) and leukemic progression

Myelodysplastic Syndromes, a heterogeneous group of hematological disorders, are characterized by abnormalities in phosphoinositide-dependent signaling, epigenetic regulators, apoptosis, and cytokine interactions within the bone marrow microenvironment, contributing to disease pathogenesis and neoplastic growth. Comprehensive knowledge of these pathways is crucial for the development of innovative therapies that aim to restore normal apoptosis and improve patient outcomes.

Hematopoietic stem cells preferentially traffic misfolded proteins to aggresomes and depend on aggrephagy to maintain protein homeostasis

Hematopoietic stem cells (HSCs) regenerate blood cells throughout life. To preserve their fitness, HSCs are particularly dependent on maintaining protein homeostasis (proteostasis). However, how HSCs purge misfolded proteins is unknown. Here, we show that in contrast to most cells that primarily utilize the proteasome to degrade misfolded proteins, HSCs preferentially traffic misfolded proteins to aggresomes in a Bag3-dependent manner and depend on aggrephagy, a selective form of autophagy, to maintain proteostasis in vivo. When autophagy is disabled, HSCs compensate by increasing proteasome activity, but proteostasis is ultimately disrupted as protein aggregates accumulate and HSC function is impaired. Bag3-deficiency blunts aggresome formation in HSCs, resulting in protein aggregate accumulation, myeloid-biased differentiation, and diminished self-renewal activity. Furthermore, HSC aging is associated with a severe loss of aggresomes and reduced autophagic flux. Protein degradation pathways are thus specifically configured in young adult HSCs to preserve proteostasis and fitness but become dysregulated during aging.