Dorsomorphin inhibits BMP signals required for embryogenesis and iron metabolism

The class-IIa HDAC inhibitor TMP269 promotes BMP-Smad signalling and is neuroprotective in in vitro and in vivo 6-hydroxydopamine models of Parkinson's disease

Degeneration of midbrain nigrostriatal dopaminergic neurons is a pathological hallmark of Parkinson's disease (PD). Peripheral delivery of a compound(s) to arrest or slow this dopaminergic degeneration is a key therapeutic goal. Pan-inhibitors of histone deacetylase (HDAC) enzymes, key epigenetic regulators, have shown therapeutic promise in PD models. However as there are several classes of HDACs (ClassI-IV), class-specific inhibition will be important to ensure target specificity. Here we examine the neuroprotective potential of the Class-IIa HDAC inhibitor, TMP269. We show that TMP269 protected against 6-hydroxydopamine (6-OHDA)-induced neurite injury in SH-SY5Y cells and cultured rat ventral mesencephalic dopaminergic neurons. We find that TMP269 upregulated the neurotrophic factor BMP2 and BMP-Smad dependent transcription signalling in SH-SY5Y cells, which was necessary for its neuroprotective effect against 6-OHDA-induced injury. Furthermore, peripheral continuous infusion of 0.5 mg/kg of TMP269 for 7 days via a mini-osmotic pump, reduced forelimb impairments induced by striatal 6-OHDA administration. TMP269 also protected dopaminergic neurons in the substantia nigra and their striatal terminals from striatal 6-OHDA-induced neurodegeneration and prevented the 6-OHDA-induced increases in the numbers of IBA1-positive microglia in the striatum and substantia nigra in vivo. TMP269 also prevented 6-OHDA-induced decreases in BMP2, pSmad1/5 and acetylated histone 3 levels, and it reversed 6-OHDA-induced increase in nuclear HDAC5 in dopaminergic neurons in the substantia nigra. These data add to the growing body of evidence that Class-IIa specific HDAC inhibitors may be pharmacological agents of interest for peripheral delivery with the goal of neuroprotection in PD.

The role of oxidative stress-mediated fibro-adipogenic progenitor senescence in skeletal muscle regeneration and repair

BACKGROUND

Stem cells play a pivotal role in tissue regeneration and repair. Skeletal muscle comprises two main stem cells: muscle stem cells (MuSCs) and fibro-adipogenic progenitors (FAPs). FAPs are essential for maintaining the regenerative milieu of muscle tissue and modulating the activation of muscle satellite cells. However, during acute skeletal muscle injury, the alterations and mechanisms of action of FAPs remain unclear.

METHODS

we employed the GEO database for bioinformatics analysis of skeletal muscle injury. A skeletal muscle injury model was established through cardiotoxin (CTX, 10µM, 50µL) injection into the tibialis anterior (TA) of C57BL/6 mice. Three days post-injury, we extracted the TA, isolated FAPs (CD31-CD45-PDGFRα+Sca-1+), and assessed the senescence phenotype through SA-β-Gal staining and Western blot. Additionally, we established a co-culture system to evaluate the capacity of FAPs to facilitate MuSCs differentiation. Finally, we alleviated the senescent of FAPs through in vitro (100 µM melatonin, 5 days) and in vivo (20 mg/kg/day melatonin, 15 days) administration experiments, confirming melatonin's pivotal role in the regeneration and repair processes of skeletal muscle.

RESULTS

In single-cell RNA sequencing analysis, we discovered the upregulation of senescence-related pathways in FAPs following injury. Immunofluorescence staining revealed the co-localization of FAPs and senescent markers in injured muscles. We established the CTX injury model and observed a reduction in the number of FAPs post-injury, accompanied by the manifestation of a senescent phenotype. Melatonin treatment was found to attenuate the injury-induced senescence of FAPs. Further co-culture experiments revealed that melatonin facilitated the restoration of FAPs' capacity to promote myoblast differentiation. Through GO and KEGG analysis, we found that the administration of melatonin led to the upregulation of AMPK pathway in FAPs, a pathway associated with antioxidant stress response. Finally, drug administration experiments corroborated that melatonin enhances skeletal muscle regeneration and repair by alleviating FAP senescence in vivo.

CONCLUSION

In this study, we first found FAPs underwent senescence and redox homeostasis imbalance after injury. Next, we utilized melatonin to enhance FAPs regenerative and repair capabilities by activating AMPK signaling pathway. Taken together, this work provides a novel theoretical foundation for treating skeletal muscle injury.

mRNA splicing variants of the transcription factor Blimp1 differentially regulate germline genes in echinoderms

Germ cell specification is an essential step in sexually reproducing animals. Echinoderms possess diverse representatives of the main mechanisms that result in this cell fate determination. Sea urchins use an inherited mechanism, whereas sea stars rely on the ancestral, induced mechanism. Blimp1 (B lymphocyte-induced maturation protein-1) is a transcriptional regulator reported in mice to function in the induction of germline cells. Here, we identify the dynamic function of Blimp1 during development in a comparative approach using the purple sea urchin, Strongylocentrotus purpuratus (inherited germline) and the batstar, Patiria miniata (induced germline). We found that Blimp1 is important for germ cell specification in both species and that multiple Blimp1 isoforms result from differential mRNA splicing in each animal. Each isoform of Blimp1 functions in distinct expression of germline determinants, including Vasa and Nanos. These results show that Blimp1 is a conserved and key regulator for germ cell specification, but divergent in function as a result of post-transcriptional modification. Overall, we conclude that Blimp1 is an intersectional node in diverse germline specification strategies and supports the concept that differential mRNA splicing is an essential mechanism in germ cell formation.

Heterotopic ossification: Current developments and emerging potential therapies

ABSTRACT

This review aimed to provide a comprehensive analysis of the etiology, epidemiology, pathology, and conventional treatment of heterotopic ossification (HO), especially emerging potential therapies. HO is the process of ectopic bone formation at non-skeletal sites. HO can be subdivided into two major forms, acquired and hereditary, with acquired HO predominating. Hereditary HO is a rare and life-threatening genetic disorder, but both acquired and hereditary form can cause severe complications, such as peripheral nerve entrapment, pressure ulcers, and disability if joint ankylosis develops, which heavily contributes to a reduced quality of life. Modalities have been proposed to treat HO, but none have emerged as the gold standard. Surgical excision remains the only effective modality; however, the optimal timing is controversial and may cause HO recurrence. Recently, potential therapeutic strategies have emerged that focus on the signaling pathways involved in HO, and small molecule inhibitors have been shown to be promising. Moreover, additional specific targets, such as small interfering RNAs (siRNAs) and non-coding RNAs, could be used to effectively block HO or develop combinatorial therapies for HO.

Dorsomorphin (DM) inhibits the ovarian development of Portunus trituberculatus by acting on the BMP signaling pathway

Bone morphogenic proteins (BMPs) regulate animal growth, cell proliferation and differentiation. The BMP signaling pathway plays an important regulatory role during ovarian follicle development in mammals. However, related studies in crustaceans are limited. The focus of this study was the key gene of the BMP signaling pathway, the BMP type I receptor. Portunus trituberculatus was injected with different concentrations of dorsomorphin (DM) and observed for one month to identify the optimal effective concentration for interference with the BMP signaling pathway. Subsequent transcriptomics, proteomics, and metabolomics measurements were performed to identify the effects of BMP signaling on ovarian development in P. trituberculatus. A preliminary mechanism of action of the BMP signaling pathway in the regulation of ovarian development was revealed through combined multiomics analysis and lipid analysis. This study provides a theoretical basis for further exploration of the molecular mechanism regulating gonadal development in crustaceans.

TGF-β1 Induces Mucosal Mast Cell Genes and is Negatively Regulated by the IL-3/ERK1/2 Axis

Mast cells develop from the myeloid lineage and are released from the bone marrow as immature cells, which then differentiate at the destination tissue based on cues from the local environment. In the liver, mast cells are recruited in diseased states to fibrogenic surroundings rich in TGF-β1. The aim of this study was to investigate TGF-β1 signaling in primary and permanent mast cells to identify common and unique mechanisms. The TGF-β receptor repertoire is similar among mast cells, with high expression of type I and type II receptors and very low expression of type III receptors (Betaglycan and Endoglin). Downstream, TGF-β1 activates the SMAD2/3 signaling axis and also SMAD1/5 with target genes Smad6 and Id1 in a transient manner. Initially, TGF-β1 upregulates the transcription of mucosal mast cell effectors Mcpt1 and Mcpt2 in all analyzed mast cells. This upregulation is reduced in the presence of IL-3, which promotes proliferation. Inhibition of ERK1/2 activation reduces proliferation and mitigates the negative effect of IL-3 on Mcpt1 mRNA and protein expression in the immortalized mast cell line PMC-306 but not in bone marrow-derived mast cells. Therefore, extracellular signal-regulated kinases ERK1/2 are identified as a mutual switch between IL-3-driven proliferation and TGF-β1-promoted mucosal mast cell differentiation in PMC-306. In conclusion, TGF-β1 promotes a mucosal gene signature and inhibits proliferation in mast cells, with these effects being counter-regulated by IL-3/ERK1/2.

A whole-animal phenotypic drug screen identifies suppressors of atherogenic lipoproteins

Lipoproteins are essential for lipid transport in all bilaterians. A single Apolipoprotein B (ApoB) molecule is the inseparable structural scaffold of each ApoB-containing lipoprotein (B-lps), which are responsible for transporting lipids to peripheral tissues. The cellular mechanisms that regulate ApoB and B-lp production, secretion, transport, and degradation remain to be fully defined. In humans, elevated levels of vascular B-lps play a causative role in cardiovascular disease. Previously, we have detailed that human B-lp biology is remarkably conserved in the zebrafish using an in vivo chemiluminescent reporter of ApoB (LipoGlo) that does not disrupt ApoB function. Thus, the LipoGlo model is an ideal system for identifying novel mechanisms of ApoB modulation and, due to the ability of zebrafish to generate many progeny, is particularly amenable to large-scale phenotypic drug screening. Here, we report a screen of roughly 3000 compounds that identified 49 unique ApoB-lowering hits. Nineteen hits passed orthogonal screening criteria. A licorice root component, enoxolone, significantly lowered B-lps only in animals that express a functional allele of the nuclear hormone receptor Hepatocyte Nuclear Factor 4α (HNF4α). Consistent with this result, inhibitors of HNF4α also reduce B-lp levels. These data demonstrate that mechanism(s) of action can be rapidly determined from a whole animal zebrafish phenotypic screen. Given the well documented role of HNF4α in human B-lp biology, these data validate the LipoGlo screening platform for identifying small molecule modulators of B-lps that play a critical role in a leading cause of worldwide mortality.

Targeting Chondrocyte Hypertrophy as Strategies for the Treatment of Osteoarthritis

Osteoarthritis (OA) is a common joint disease characterized by pain and functional impairment, which severely impacts the quality of life of middle-aged and elderly individuals. During normal bone development, chondrocyte hypertrophy is a natural physiological process. However, in the progression of OA, chondrocyte hypertrophy becomes one of its key pathological features. Although there is no definitive evidence to date confirming that chondrocyte hypertrophy is the direct cause of OA, substantial experimental data indicate that it plays an important role in the disease's pathogenesis. In this review, we first explore the mechanisms underlying chondrocyte hypertrophy in OA and offer new insights. We then propose strategies for inhibiting chondrocyte hypertrophy from the perspectives of targeting signaling pathways and tissue engineering, ultimately envisioning the future prospects of OA treatment.

Recombinant dsAAV9-mediated Endogenous Overexpression of Macrophage Migration Inhibitory Factor Alleviates Myocardial Ischemia-Reperfusion Injury via Activating AMPK and ERK1/2 Signaling Pathways

PURPOSE

To investigate the protective effect and mechanism of enhanced expression of endogenous macrophage migration inhibitory factor (MIF) on cardiac ischemia-reperfusion (I/R) injury.

METHODS

A recombinant double-stranded adeno-associated virus serotype 9 with MIF or green fluorescent protein (GFP) genes (dsAAV9-MIF/GFP) was transduced into mice and neonatal rat ventricular myocytes (NRVMs). The models of cardiac 60 min ischemia and 24 h reperfusion and 12 h hypoxia/12 h reoxygenation (H/R) were established in mice and NRVMs, respectively. Infarct size, cardiac remodeling, and related signaling pathways were assessed.

RESULTS

The dsAAV9 vector demonstrated strong transduction efficacy and cardiac affinity. Cardiac overexpression of MIF led to a 35.3% reduction in infarct size and improved cardiac function following I/R injury. In the dsAAV9-MIF group, the AMP-activated protein kinase (AMPK) signaling pathway was activated, and autophagy was enhanced during the ischemic period. During reperfusion, the extracellular signal-regulated kinases 1 and 2 (ERK1/2) signaling pathway was upregulated, leading to reduced cardiac apoptosis. In vitro, transfection with MIF in NRVMs also upregulated AMPK and ERK1/2 signaling during hypoxia and reoxygenation, respectively. Furthermore, MIF overexpression significantly improved autophagy and mitochondrial function, evidenced by an increased LC3-II/I ratio and enhanced mitochondrial membrane potential (ΔΨm), with these effects reversed by the AMPK inhibitor compound C. Additionally, MIF overexpression led to a 60% reduction in the apoptosis rate of cardiomyocytes subjected to H/R and decreased the Bax/Bcl-2 ratio, partially through the ERK1/2 signaling pathway.

CONCLUSION

Enhanced endogenous MIF expression via the dsAAV9 vector provides significant cardioprotection against I/R injury by activating the AMPK and ERK1/2 signaling pathways. Our findings suggest that targeting MIF may represent a viable therapeutic strategy for severe and prolonged I/R injury.

MRSA Inhibitory Activity of Some New Pyrazolo[1,5-a]pyrimidines Linked to Arene and/or Furan or Thiophene Units

Methicillin-resistant Staphylococcus aureus (MRSA) is a major contributor to hospital-acquired infections and is highly resistant to treatment. Ongoing research focuses on developing new antimicrobial medications to prevent the spread of resistance. A facile method was employed to efficiently synthesize new pyrazolo[1,5-a]pyrimidines in 84-93 % yields by reacting 4-benzyl-1H-pyrazole-3,5-diamine with the respective α,β-unsaturated ketones. The reaction was carried out in ethanol containing 1.2 equivalents of potassium hydroxide at reflux for 5-6 h. The new products are attached to a para-substituted aryl group with variable electronic properties at pyrazolopyrimidine-C5, in addition to one of three units at C7, namely phenyl, thiophen-2-yl, or furan-2-yl units. A wide spectrum of antibacterial activity was displayed by the new pyrimidines against six different bacterial strains. In general, pyrimidines attached to furan-2-yl units at C7, in addition to another aryl unit at C5, attached to 4-Me or 4-OMe groups, demonstrate significant antibacterial activity, particularly against S. aureus strain. They had MIC/MBC of 2.5/5.1 and 2.4/4.9 μM, respectively, which exceeded that of ciprofloxacin. Moreover, they demonstrate more effective MRSA inhibitory activity than linezolid, with MIC/MBC values up to 4.9/19.7 and 2.4/19.7 μM against MRSA ATCC:33591 and ATCC:43300 strains, respectively.

Disruption of BMP and FGF signaling prior to blastema formation causes permanent bending and skeletal malformations in Poecilia latipinna tail fin

Teleost fish, such as Poecilia latipinna, exhibit remarkable regenerative capabilities, making them excellent models for studying tissue regrowth. They regenerate body parts like the tail fin through epimorphic regeneration, involving wound healing, blastema formation (a pool of proliferative cells), and tissue differentiation. Bone Morphogenetic Protein (BMP) and Fibroblast Growth Factor (FGF) signaling pathways play crucial roles in this process, but their specific functions during blastema formation remain unclear. To explore this, BMP and FGF signaling were inhibited using targeted drug treatments prior to blastema formation in amputated tail fins. The treatment group of P. latipinna received drugs at set intervals, and analyses were conducted using skeletal staining, gene expression via quantitative real-time PCR, and protein analysis with Western blotting to assess blastema formation, extracellular matrix (ECM) remodeling, and skeletal patterning. Dual inhibition of BMP and FGF pathways led to significant regenerative defects, including bent blastema and disrupted bone structure, along with downregulation of essential patterning genes like sonic hedgehog (Shh) and bmp2b. Additionally, ECM remodeling and epithelial-to-mesenchymal transition (EMT) were impaired, as shown by reduced matrix metalloproteinases (MMP2 and MMP9), hindering cell migration and blastema stability. Cell proliferation was markedly decreased, as evidenced by reduced proliferating cell nuclear antigen (PCNA) expression and bromodeoxyuridine (BrdU) incorporation, while apoptosis increased, with elevated markers like caspase 3 (casp3) and higher DNA fragmentation. These findings indicate that BMP and FGF signaling are essential for blastema formation and skeletal patterning, with their inhibition causing major regenerative abnormalities.

The effect of Miya on skeletal muscle changes by regulating gut microbiota in rats with osteoarthritis through AMPK pathway

BACKGROUND

The study aimed to explore whether Miya (MY), a kind of Clostridium butyricum, regulated osteoarthritis (OA) progression through adenosine 5'-monophosphate-activated protein kinase (AMPK) pathway.

METHODS

The OA rats were orally given MY daily for 4 weeks and were intramuscularly injected with AMPK inhibitor once a week for 4 weeks. Hematoxylin eosin (HE) staining was used to observe the histological morphology of the knee joint. The levels of succinate dehydrogenase (SDH) and muscle glycogen (MG) in the tibia muscle of rats were detected by the corresponding kits, as well as the expression of related genes/proteins were assessed by real-time quantitative PCR (RT-qPCR) and western blot.

RESULTS

HE staining suggested that MY suppressed the symptoms of OA, which was abolished by AMPK inhibitor. Furthermore, the SDH and MG contents in the OA + MY + AMPK inhibitor group were lower than in the OA + MY group. At last, the levels of AMPK, PI3K, AKT1, Ldh, Myod, Chrna1, and Chrnd were notably decreased after AMPK inhibitor treatment, while the levels of Lcad and Mcad were up-regulated by AMPK inhibitor. Furthermore, their protein expression levels detected by western blot were consistent with those from RT-qPCR.

CONCLUSION

MY may partially regulate skeletal muscle changes and prevente OA development through the AMPK pathway.

Hepcidin Is a Valuable Therapeutic Target for Colorectal Cancer

Colorectal cancer (CRC) is one of the most frequent neoplasms and a major cause of cancer death worldwide. Despite recent advances in treatment approaches, the prognosis of advanced CRC remains poor, thus indicating the necessity of more effective treatments for CRC patients. CRC cells produce high levels of hepcidin, a peptide hormone that binds to the membrane-bound ferroportin and promotes its internalization and degradation, thus sequestering iron into the cancer cells with the downstream effect of enhancing tumor growth. Additionally, CRC cell-expressed hepcidin prolongs cell survival and, by targeting both CD8+ T cells and myeloid cells, restrains the induction of an efficient immune response against tumor antigens. The greatest expression of hepcidin is found in patients with metastatic CRC, and CRC patients with high hepcidin content have a worse survival rate than those with low hepcidin content. In the present article, we review the data supporting the prominent role of hepcidin in colon tumorigenesis and discuss how hepcidin inhibitors can help treat CRC patients in the metastatic setting with particular regard to the impact of hepcidin modulation on immunotherapeutic outcomes.

Bone phenotyping of murine hemochromatosis models with deficiencies of Hjv, Alk2, or Alk3: The influence of sex and the bone compartment

Osteopenia is frequently observed in patients with iron overload, especially in those with HFE-dependent hereditary hemochromatosis (HH). Interestingly, not all mouse models of HH show bone loss, suggesting that iron overload alone may not suffice to induce bone loss. In this study, the bone phenotypes of Hjv-/- and hepatocyte-specific Alk2- and Alk3-deficient mice as additional mouse models of HH were investigated to further clarify, how high iron levels lead to bone loss and which signaling mechanisms are operational. Neither male nor female 12-week-old Hjv-/- mice had an altered trabecular or cortical bone mass or bone turnover, despite severe iron overload. Male 12-month-old Hjv-/- mice even presented with a higher femoral trabecular bone volume compared to wildtype mice. Similarly, female mice with hepatocyte-specific Alk2 or Alk3 deficiency did not show an altered bone phenotype at 3, 6, and 12 months of age. Male hepatocyte-specific Alk3-deficient mice also had a normal trabecular bone mass at all ages analyzed, despite showing increased bone resorption and decreased bone formation parameters. Interestingly, hepatocyte-specific Alk2-deficient mice showed reduced femoral trabecular bone at 6 months of age due to suppressed bone formation. Cortical thickness at the femur was reduced in both, 6-month-old male hepatocyte-specific Alk2- and Alk3-deficient mice. Raising hepatocyte-specific Alk2-deficient male mice on an iron-deficient diet rescued the bone phenotype. Taken together, despite iron overload, trabecular bone microarchitecture was not altered in mice deficient of Hjv or Alk3. Only male hepatocyte-specific Alk2-deficient mice showed site-specific lower trabecular and cortical bone mass at the femur, which was dependent on iron. Thus, bone loss does not correlate with the extent of iron overload in these mouse models, but may relate to the amount of iron-loaded macrophages, as precursors of osteoclasts, in the bone marrow.

Discovery of highly potent and ALK2/ALK1 selective kinase inhibitors using DNA-encoded chemistry technology

Activin receptor type 1 (ACVR1; ALK2) and activin receptor like type 1 (ACVRL1; ALK1) are transforming growth factor beta family receptors that integrate extracellular signals of bone morphogenic proteins (BMPs) and activins into Mothers Against Decapentaplegic homolog 1/5 (SMAD1/SMAD5) signaling complexes. Several activating mutations in ALK2 are implicated in fibrodysplasia ossificans progressiva (FOP), diffuse intrinsic pontine gliomas, and ependymomas. The ALK2 R206H mutation is also present in a subset of endometrial tumors, melanomas, non-small lung cancers, and colorectal cancers, and ALK2 expression is elevated in pancreatic cancer. Using DNA-encoded chemistry technology, we screened 3.94 billion unique compounds from our diverse DNA-encoded chemical libraries (DECLs) against the kinase domain of ALK2. Off-DNA synthesis of DECL hits and biochemical validation revealed nanomolar potent ALK2 inhibitors. Further structure-activity relationship studies yielded center for drug discovery (CDD)-2789, a potent [NanoBRET (NB) cell IC50: 0.54 μM] and metabolically stable analog with good pharmacological profile. Crystal structures of ALK2 bound with CDD-2281, CDD-2282, or CDD-2789 show that these inhibitors bind the active site through Van der Waals interactions and solvent-mediated hydrogen bonds. CDD-2789 exhibits high selectivity toward ALK2/ALK1 in KINOMEscan analysis and NB K192 assay. In cell-based studies, ALK2 inhibitors effectively attenuated activin A and BMP-induced Phosphorylated SMAD1/5 activation in fibroblasts from individuals with FOP in a dose-dependent manner. Thus, CDD-2789 is a valuable tool compound for further investigation of the biological functions of ALK2 and ALK1 and the therapeutic potential of specific inhibition of ALK2.

Oxyberberine Inhibits Hepatic Gluconeogenesis via AMPK-Mediated Suppression of FoxO1 and CRTC2 Signaling Axes

Oxyberberine (OBB), a natural metabolite of berberine, has been shown to exhibit inhibitory effects on gluconeogenesis in our previous work. This work was designed to investigate the potential effects and underlying mechanisms of OBB on hepatic gluconeogenesis. Our work found that OBB significantly inhibited the expressions of glucose 6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK), and decreased the glucose production in palmitic acid-induced HepG2 cells. Then, AMPK/Akt/FoxO1 and AMPK/CRTC2 signaling pathways were confirmed by transcriptomics and network pharmacology analyses. It was shown that AMPK activation may phosphorylate and promote nuclear exclusion of FoxO1 and CRTC2, two key regulators of hepatic gluconeogenesis transcriptional pathways, resulting in the inhibition of gluconeogenesis under OBB administration. Afterwards, AMPK/Akt/FoxO1, AMPK/CRTC2 signaling pathways were evidenced by western blot, immunoprecipitation and confocal immunofluorescence, and the targeted inhibitor (Compound C) and siRNA of AMPK were applied for further mechanism verification. Moreover, it was found that OBB treatment activated AMPK/Akt/FoxO1 and AMPK/CRTC2 signaling pathways to decrease hepatic gluconeogenesis in db/db mice. Similarly, the in vivo inhibitory effects of OBB on gluconeogenesis were also diminished by AMPK inhibition. Our work demonstrated that OBB can inhibit hepatic gluconeogenesis in vitro and in vivo, and its underlying mechanisms were associated with AMPK-mediated suppression of FoxO1 and CRTC2 signaling axes.

β-Hydroxybutyrate enhances chondrocyte mitophagy and reduces cartilage degeneration in osteoarthritis via the HCAR2/AMPK/PINK1/Parkin pathway

Osteoarthritis (OA) is widely recognized as the prevailing joint disease associated with aging. The ketogenic diet (KD) has been postulated to impede the advancement of various inflammatory ailments. β-Hydroxybutyrate (βOHB), a prominent constituent of ketone bodies, has recently been proposed to possess crucial signaling capabilities. In this study, we propose to explore the role and mechanism of βOHB in OA. Tissue staining and inflammatory factor assay were employed to evaluate the impacts of KD and βOHB on OA rats. The oxidative stress conditions in chondrocytes were induced using tert-butyl hydroperoxide (TBHP). The mechanisms were determined using the siRNA of hydroxycarboxylic acid receptor 2 (HCAR2), the antagonist of adenosine monophosphate-activated protein kinase (AMPK), and the inhibitor of mitophagy. The administration of KD demonstrated a reduction in pathological damage to cartilage, as well as a decrease in plasma levels of inflammatory factors. Furthermore, it resulted in an increase in the concentration of βOHB in the blood and synovial fluid. In vitro experiments showed that βOHB facilitated mitophagy and adenosine triphosphate production. Besides, βOHB mitigated chondrocyte senescence, inflammatory factors secretion, extracellular matrix degradation, and apoptosis induced by TBHP. Subsequent investigations indicated that the protective effects of βOHB were no longer observed following the knockdown of HCAR2, the antagonist of AMPK, or the inhibitor of mitophagy. Moreover, in vivo studies suggested that βOHB played a protective role by targeting the HCAR2-AMPK-PINK1 axis. In conclusion, βOHB enhanced chondrocyte mitophagy through the HCAR2/AMPK/PINK1/Parkin pathway, offering a potential therapeutic approach for the treatment of OA.

Temporal BMP4 effects on mouse embryonic and extraembryonic development

The developing placenta, which in mice originates through the extraembryonic ectoderm (ExE), is essential for mammalian embryonic development. Yet unbiased characterization of the differentiation dynamics of the ExE and its interactions with the embryo proper remains incomplete. Here we develop a temporal single-cell model of mouse gastrulation that maps continuous and parallel differentiation in embryonic and extraembryonic lineages. This is matched with a three-way perturbation approach to target signalling from the embryo proper, the ExE alone, or both. We show that ExE specification involves early spatial and transcriptional bifurcation of uncommitted ectoplacental cone cells and chorion progenitors. Early BMP4 signalling from chorion progenitors is required for proper differentiation of uncommitted ectoplacental cone cells and later for their specification towards trophoblast giant cells. We also find biphasic regulation by BMP4 in the embryo. The early ExE-originating BMP4 signal is necessary for proper mesoendoderm bifurcation and for allantois and primordial germ cell specification. However, commencing at embryonic day 7.5, embryo-derived BMP4 restricts the primordial germ cell pool size by favouring differentiation of their extraembryonic mesoderm precursors towards an allantois fate. ExE and embryonic tissues are therefore entangled in time, space and signalling axes, highlighting the importance of their integrated understanding and modelling in vivo and in vitro.

LKB1 suppresses KSHV reactivation and promotes primary effusion lymphoma progression

Viruses normally reprogram the host cell metabolic pathways as well as metabolic sensors to facilitate their persistence. The serine-threonine liver kinase B1 (LKB1) is a master upstream kinase of 5'-AMP-activated protein kinase (AMPK) that senses the energy status and therefore regulates the intracellular metabolic homeostasis. Previous studies showed that AMPK restricts Kaposi's sarcoma-associated herpesvirus (KSHV) lytic replication in endothelial cells during primary infection and promotes primary effusion lymphoma (PEL) cell survival. However, the role of LKB1 in KSHV lytic reactivation and KSHV-associated malignancies is unclear. In this study, we found that LKB1 is phosphorylated or activated in KSHV-positive PEL cells. Mechanistically, KSHV-encoded vCyclin mediated LKB1 activation in PEL cells, as vCyclin knockout ablated, while vCyclin overexpression enhanced LKB1 activation. Furthermore, knockdown of LKB1 inactivated AMPK and induced KSHV reactivation, as indicated by the increased expression of viral lytic genes and the increased virions in supernatants. Accordingly, AMPK inhibition by functional knockdown or a pharmacologic inhibitor, Compound C, promoted KSHV reactivation in PEL cells. Furthermore, inhibition of either LKB1 or AMPKα1 efficiently induced cell death by apoptosis of PEL cells both in vitro and in vivo. Together, these results identify LKB1 as a vulnerable target for PEL, which could be potentially exploited for treating other virus-associated diseases.IMPORTANCEKaposi's sarcoma-associated herpesvirus (KSHV) is an oncogenic virus associated with several human cancers, such as primary effusion lymphoma (PEL). Here, we showed that serine-threonine liver kinase B1 (LKB1), upstream of 5' AMP-activated protein kinase (AMPK), is activated by KSHV-encoded vCyclin and maintains KSHV latency in PEL cells. Inhibition of either LKB1 or AMPK enhances KSHV lytic replication from latency, which at least partially accounts for PEL cell death by apoptosis. Compound C, a potent AMPK inhibitor, induced KSHV reactivation and efficiently inhibited PEL progression in vivo. Thus, our work revealed that LKB1 is a potential therapeutic target for KSHV-associated cancers.

Expression of Kielin/chordin-like protein is regulated by BMP-2 in osteoblasts

Bone morphogenetic protein (BMP), an osteoinductive factor, is a cytokine that induces osteoblast differentiation and mineralization, and expected to be applicable for hard tissue reconstruction. Kielin/chordin-like protein (Kcp), a member of the family of cysteine-rich proteins, enhances BMP signaling. The present study found that expression of Kcp in osteoblasts was induced by BMP-2 in a concentration- and time-dependent manner. Up-regulation of Kcp by BMP-2 was inhibited by Dorsomorphin, a SMAD signaling inhibitor. The involvement of up-regulation of Kcp by BMP-2 in induction of osteoblast differentiation by BMP-2 was also examined, which showed that suppression of Kcp expression by si Kcp partially inhibited induction of osteoblast differentiation and mineralization by BMP-2. Together, these results suggest that Kcp induced by BMP-2 functions to provide positive feedback for promotion of osteoblastic differentiation and mineralization by BMP-2 in osteoblasts.

Silencing of tropomodulin 1 inhibits acute myeloid leukemia cell proliferation and tumor growth by elevating karyopherin alpha 2-mediated autophagy

Evidence shows that tropomodulin 1 (TMOD1) is a powerful diagnostic marker in the progression of several cancer types. However, the regulatory mechanism of TMOD1 in tumor progression is still unclear. Here, we showed that TMOD1 was highly expressed in acute myeloid leukemia (AML) specimens, and TMOD1-silencing inhibited cell proliferation by inducing autophagy in AML THP-1 and MOLM-13 cells. Mechanistically, the C-terminal region of TMOD1 directly bound to KPNA2, and TMOD1-overexpression promoted KPNA2 ubiquitylation and reduced KPNA2 levels. In contrast, TMOD1-silencing increased KPNA2 levels and facilitated the nuclear transfer of KPNA2, then subsequently induced autophagy and inhibited cell proliferation by increasing the nucleocytoplasmic transport of p53 and AMPK activation. KPNA2/p53 inhibitors attenuated autophagy induced by silencing TMOD1 in AML cells. Silencing TMOD1 also inhibited tumor growth by elevating KPNA2-mediated autophagy in nude mice bearing MOLM-13 xenografts. Collectively, our data demonstrated that TMOD1 could be a novel therapeutic target for AML treatment.

Discovery of Two Highly Selective Structurally Orthogonal Chemical Probes for Activin Receptor-like Kinases 1 and 2

Activin receptor-like kinases 1-7 (ALK1-7) regulate a complex network of SMAD-independent as well as SMAD-dependent signaling pathways. One of the widely used inhibitors for functional investigations of these processes, in particular for bone morphogenetic protein (BMP) signaling, is LDN-193189. However, LDN-193189 has insufficient kinome-wide selectivity complicating its use in cellular target validation assays. Herein, we report the identification and comprehensive characterization of two chemically distinct highly selective inhibitors of ALK1 and ALK2, M4K2234 and MU1700, along with their negative controls. We show that both MU1700 and M4K2234 efficiently block the BMP pathway via selective in cellulo inhibition of ALK1/2 kinases and exhibit favorable in vivo profiles in mice. MU1700 is highly brain penetrant and shows remarkably high accumulation in the brain. These high-quality orthogonal chemical probes offer the selectivity required to become widely used tools for in vitro and in vivo investigation of BMP signaling.

Cyanidin-3-O-glucoside alleviates ethanol-induced liver injury by promoting mitophagy in a Gao-binge mouse model of alcohol-associated liver disease

BACKGROUND

Alcohol-associated liver disease (ALD) is a leading cause of liver disease-related deaths worldwide. Unfortunately, approved medications for the treatment of this condition are quite limited. One promising candidate is the anthocyanin, Cyanidin-3-O-glucoside (C3G), which has been reported to protect mice against hepatic lipid accumulation, as well as fibrosis in different animal models. However, the specific effects and mechanisms of C3G on ALD remain to be investigated.

EXPERIMENTAL APPROACH

In this report, a Gao-binge mouse model of ALD was used to investigate the effects of C3G on ethanol-induced liver injury. The mechanisms of these C3G effects were assessed using AML12 hepatocytes.

RESULTS

C3G administration ameliorated ethanol-induced liver injury by suppressing hepatic oxidative stress, as well as through reducing hepatic lipid accumulation and inflammation. Mechanistically, C3G activated the AMPK pathway and enhanced mitophagy to eliminate damaged mitochondria, thus reducing mitochondria-derived reactive oxidative species in ethanol-challenged hepatocytes.

CONCLUSIONS

The results of this study indicate that mitophagy plays a potentially important role underlying the hepatoprotective action of C3G, as demonstrated in a Gao-binge mouse model of ALD. Accordingly, C3G may serve as a promising, new therapeutic drug candidate for use in ALD.

Human induced pluripotent stem cell/embryonic stem cell-derived pyramidal neuronal precursors show safety and efficacy in a rat spinal cord injury model

Nerve regeneration and circuit reconstruction remain a challenge following spinal cord injury (SCI). Corticospinal pyramidal neurons possess strong axon projection ability. In this study, human induced pluripotent stem cells (iPSCs) were differentiated into pyramidal neuronal precursors (PNPs) by addition of small molecule dorsomorphin into the culture. iPSC-derived PNPs were transplanted acutely into a rat contusion SCI model on the same day of injury. Following engraftment, the SCI rats showed significantly improved motor functions compared with vehicle control group as revealed by behavioral tests. Eight weeks following engraftment, the PNPs matured into corticospinal pyramidal neurons and extended axons into distant host spinal cord tissues, mostly in a caudal direction. Host neurons rostral to the lesion site also grew axons into the graft. Possible synaptic connections as a bridging relay may have been formed between host and graft-derived neurons, as indicated by pre- and post-synaptic marker staining and the regulation of chemogenetic regulatory systems. PNP graft showed an anti-inflammatory effect at the injury site and could bias microglia/macrophages towards a M2 phenotype. In addition, PNP graft was safe and no tumor formation was detected after transplantation into immunodeficient mice and SCI rats. The potential to reconstruct a neuronal relay circuitry across the lesion site and to modulate the microenvironment in SCI makes PNPs a promising cellular candidate for treatment of SCI.

Dorsomorphin attenuates ABCG2-mediated multidrug resistance in colorectal cancer

Colorectal cancer is a common malignant tumor with high mortality, for which chemotherapy resistance is one of the main reasons. The high expression of ABCG2 in the cancer cells and expulsion of anticancer drugs directly cause multidrug resistance (MDR). Therefore, the development of new ABCG2 inhibitors that block the active causes of MDR may provide a strategy for the treatment of colorectal cancer. In this study, we find that dorsomorphin (also known as compound C or BML-275) potently inhibits the transporter activity of ABCG2, thereby preserving the chemotherapeutic agents mitoxantrone and doxorubicin to antagonize MDR in ABCG2-overexpressing colorectal cancer cells. Additionally, dorsomorphin does not alter ABCG2 protein expression. The results of molecular docking studies show that dorsomorphin is bound stably to the ABCG2-binding pocket, suggesting that dorsomorphin is a potent ABCG2 inhibitor that attenuates ABCG2-mediated MDR in colorectal cancer.

Preclinical evidence using synthetic compounds and natural products indicates that AMPK represents a potential pharmacological target for the therapy of pulmonary diseases

Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) is a highly conserved eukaryotic enzyme discovered as a key regulator of cellular energy homeostasis, with anti-inflammation, antioxidative stress, anticancer, and antifibrosis beneficial effects. AMPK is dysregulated in human pulmonary diseases such as acute lung injury, nonsmall cell lung cancer, pulmonary fibrosis, chronic obstructive pulmonary disease, and asthma. This review provides an overview of the beneficial role of natural, synthetic, and Chinese traditional medicines AMPK modulators in pulmonary diseases, and highlights the role of the AMPK signaling pathway in the lung, emphasizing the importance of finding lead compounds and drugs that can target and modulate AMPK to treat the lung diseases.

Anemia in patients receiving anticancer treatments: focus on novel therapeutic approaches

Anemia is common in cancer patients and impacts on quality of life and prognosis. It is typically multifactorial, often involving different pathophysiological mechanisms, making treatment a difficult task. In patients undergoing active anticancer treatments like chemotherapy, decreased red blood cell (RBC) production due to myelosuppression generally predominates, but absolute or functional iron deficiency frequently coexists. Current treatments for chemotherapy-related anemia include blood transfusions, erythropoiesis-stimulating agents, and iron supplementation. Each option has limitations, and there is an urgent need for novel approaches. After decades of relative immobilism, several promising anti-anemic drugs are now entering the clinical scenario. Emerging novel classes of anti-anemic drugs recently introduced or in development for other types of anemia include activin receptor ligand traps, hypoxia-inducible factor-prolyl hydroxylase inhibitors, and hepcidin antagonists. Here, we discuss their possible role in the treatment of anemia observed in patients receiving anticancer therapies.

Embryonic Amoxicillin Exposure Has Limited Impact on Liver Development but Increases Susceptibility to NAFLD in Zebrafish Larvae

Amoxicillin is commonly used in clinical settings to target bacterial infection and is frequently prescribed during pregnancy. Investigations into its developmental toxicity and effects on disease susceptibility are not comprehensive. Our present study examined the effects of embryonic amoxicillin exposure on liver development and function, especially the effects on susceptibility to non-alcoholic fatty liver disease (NAFLD) using zebrafish as an animal model. We discovered that embryonic amoxicillin exposure did not compromise liver development, nor did it induce liver toxicity. However, co-treatment of amoxicillin and clavulanic acid diminished BESP expression, caused bile stasis and induced liver toxicity. Embryonic amoxicillin exposure resulted in elevated expression of lipid synthesis genes and exacerbated hepatic steatosis in a fructose-induced NAFLD model, indicating embryonic amoxicillin exposure increased susceptibility to NAFLD in zebrafish larvae. In summary, this research broadens our understanding of the risks of amoxicillin usage during pregnancy and provides evidence for the impact of embryonic amoxicillin exposure on disease susceptibility in offspring.

Stiffness and BMP-2 Mimetic Peptide Jointly Regulate the Osteogenic Differentiation of Rat Bone Marrow Stromal Cells in a Gelatin Cryogel

Both biochemical and mechanical cues could regulate the function of stem cells, but the interaction mechanism of their signaling pathway remains unclear, especially in the three-dimensional (3D) culture mode. Higher matrix stiffness promotes osteogenic differentiation of stem cells, and bone morphogenic protein-2 (BMP-2) has been clinically applied to promote bone regeneration. Here, the crosstalk of extracellular mechanical signals on BMP-2 signaling was investigated in rat bone marrow stromal cells (rMSCs) cultured inside cryogels with interconnective pores. Stiff cryogel independently promoted osteogenic differentiation and enhanced the autocrine secretion of BMP-2, thus stimulating increased phosphorylation levels of the Smad1/5/8 complex. BMP-2 mimetic peptide (BMMP) and high cryogel stiffness jointly guided the osteogenic differentiation of rMSCs. Inhibition of rho-associated kinase (ROCK) by Y-27632 or inhibition of nonmuscle myosin II (NM II) by blebbistatin showed that osteogenesis induction by BMP-2 signaling, as well as autocrine secretion of BMP-2 and phosphorylation of the Smad complex, requires the involvement of cytoskeletal tension and ROCK pathway signaling. An interconnective microporous cryogel scaffold promoted rMSC osteogenic differentiation by combining matrix stiffness and BMMP, and it accelerated critical cranial defect repair in the rat model.

GPR68-ATF4 signaling is a novel prosurvival pathway in glioblastoma activated by acidic extracellular microenvironment

BACKGROUND

Glioblastoma multiforme (GBM) stands as a formidable challenge in oncology because of its aggressive nature and severely limited treatment options. Despite decades of research, the survival rates for GBM remain effectively stagnant. A defining hallmark of GBM is a highly acidic tumor microenvironment, which is thought to activate pro-tumorigenic pathways. This acidification is the result of altered tumor metabolism favoring aerobic glycolysis, a phenomenon known as the Warburg effect. Low extracellular pH confers radioresistant tumors to glial cells. Notably GPR68, an acid sensing GPCR, is upregulated in radioresistant GBM. Usage of Lorazepam, which has off target agonism of GPR68, is linked to worse clinical outcomes for a variety of cancers. However, the role of tumor microenvironment acidification in GPR68 activation has not been assessed in cancer. Here we interrogate the role of GPR68 specifically in GBM cells using a novel highly specific small molecule inhibitor of GPR68 named Ogremorphin (OGM) to induce the iron mediated cell death pathway: ferroptosis.

METHOD

OGM was identified in a non-biased zebrafish embryonic development screen and validated with Morpholino and CRISPR based approaches. Next, A GPI-anchored pH reporter, pHluorin2, was stably expressed in U87 glioblastoma cells to probe extracellular acidification. Cell survival assays, via nuclei counting and cell titer glo, were used to demonstrate sensitivity to GPR68 inhibition in twelve immortalized and PDX GBM lines. To determine GPR68 inhibition's mechanism of cell death we use DAVID pathway analysis of RNAseq. Our major indication, ferroptosis, was then confirmed by western blotting and qRT-PCR of reporter genes including TFRC. This finding was further validated by transmission electron microscopy and liperfluo staining to assess lipid peroxidation. Lastly, we use siRNA and CRISPRi to demonstrate the critical role of ATF4 suppression via GPR68 for GBM survival.

RESULTS

We used a pHLourin2 probe to demonstrate how glioblastoma cells acidify their microenvironment to activate the commonly over expressed acid sensing GPCR, GPR68. Using our small molecule inhibitor OGM and genetic means, we show that blocking GPR68 signaling results in robust cell death in all thirteen glioblastoma cell lines tested, irrespective of genetic and phenotypic heterogeneity, or resistance to the mainstay GBM chemotherapeutic temozolomide. We use U87 and U138 glioblastoma cell lines to show how selective induction of ferroptosis occurs in an ATF4-dependent manner. Importantly, OGM was not-acutely toxic to zebrafish and its inhibitory effects were found to spare non-malignant neural cells.

CONCLUSION

These results indicate GPR68 emerges as a critical sensor for an autocrine pro-tumorigenic signaling cascade triggered by extracellular acidification in glioblastoma cells. In this context, GPR68 suppresses ATF4, inhibition of GPR68 increases expression of ATF4 which leads to ferroptotic cell death. These findings provide a promising therapeutic approach to selectively induce ferroptosis in glioblastoma cells while sparing healthy neural tissue.

Identification of signalling pathways involved in gill regeneration in zebrafish

The occurrence of regeneration of the organs involved in respiratory gas exchange amongst vertebrates is heterogeneous. In some species of amphibians and fishes, the gills regenerate completely following resection or amputation, whereas in mammals, only partial, facultative regeneration of lung tissue occurs following injury. Given the homology between gills and lungs, the capacity of gill regeneration in aquatic species is of major interest in determining the underlying molecular or signalling pathways involved in respiratory organ regeneration. In the present study, we used adult zebrafish (Danio rerio) to characterize signalling pathways involved in the early stages of gill regeneration. Regeneration of the gills was induced by resection of gill filaments and observed over a period of up to 10 days. We screened for the effects on regeneration of the drugs SU5402, dorsomorphin and LY411575, which inhibit FGF, BMP or Notch signalling pathways, respectively. Exposure to each drug for 5 days significantly reduced regrowth of filament tips in regenerating tissue, compared with unresected controls. In separate experiments under normal conditions of regeneration, we used reverse transcription quantitative PCR and observed an increased expression of genes encoding for the bone morphogenetic factor, Bmp2b, fibroblast growth factor, Fgf8a, a transcriptional regulator (Her6) involved in Notch signalling, and Sonic Hedgehog (Shha), in regenerating gills at 10 day post-resection, compared with unresected controls. In situ hybridization confirmed that all four genes were expressed in regenerating gill tissue. This study implicates BMP, FGF, Notch and Shh signalling in gill regeneration in zebrafish.

BAY-3827 and SBI-0206965: Potent AMPK Inhibitors That Paradoxically Increase Thr172 Phosphorylation

AMP-activated protein kinase (AMPK) is the central component of a signalling pathway that senses energy stress and triggers a metabolic switch away from anabolic processes and towards catabolic processes. There has been a prolonged focus in the pharmaceutical industry on the development of AMPK-activating drugs for the treatment of metabolic disorders such as Type 2 diabetes and non-alcoholic fatty liver disease. However, recent findings suggest that AMPK inhibitors might be efficacious for treating certain cancers, especially lung adenocarcinomas, in which the PRKAA1 gene (encoding the α1 catalytic subunit isoform of AMPK) is often amplified. Here, we study two potent AMPK inhibitors, BAY-3827 and SBI-0206965. Despite not being closely related structurally, the treatment of cells with either drug unexpectedly caused increases in AMPK phosphorylation at the activating site, Thr172, even though the phosphorylation of several downstream targets in different subcellular compartments was completely inhibited. Surprisingly, the two inhibitors appear to promote Thr172 phosphorylation by different mechanisms: BAY-3827 primarily protects against Thr172 dephosphorylation, while SBI-0206965 also promotes phosphorylation by LKB1 at low concentrations, while increasing cellular AMP:ATP ratios at higher concentrations. Due to its greater potency and fewer off-target effects, BAY-3827 is now the inhibitor of choice for cell studies, although its low bioavailability may limit its use in vivo.

ADP-dependent glucokinase controls metabolic fitness in prostate cancer progression

BACKGROUND

Cell metabolism plays a pivotal role in tumor progression, and targeting cancer metabolism might effectively kill cancer cells. We aimed to investigate the role of hexokinases in prostate cancer (PCa) and identify a crucial target for PCa treatment.

METHODS

The Cancer Genome Atlas (TCGA) database, online tools and clinical samples were used to assess the expression and prognostic role of ADP-dependent glucokinase (ADPGK) in PCa. The effect of ADPGK expression on PCa cell malignant phenotypes was validated in vitro and in vivo. Quantitative proteomics, metabolomics, and extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) tests were performed to evaluate the impact of ADPGK on PCa metabolism. The underlying mechanisms were explored through ADPGK overexpression and knockdown, co-immunoprecipitation (Co-IP), ECAR analysis and cell counting kit-8 (CCK-8) assays.

RESULTS

ADPGK was the only glucokinase that was both upregulated and predicted worse overall survival (OS) in prostate adenocarcinoma (PRAD). Clinical sample analysis demonstrated that ADPGK was markedly upregulated in PCa tissues vs. non-PCa tissues. High ADPGK expression indicates worse survival outcomes, and ADPGK serves as an independent factor of biochemical recurrence. In vitro and in vivo experiments showed that ADPGK overexpression promoted PCa cell proliferation and migration, and ADPGK inhibition suppressed malignant phenotypes. Metabolomics, proteomics, and ECAR and OCR tests revealed that ADPGK significantly accelerated glycolysis in PCa. Mechanistically, ADPGK binds aldolase C (ALDOC) to promote glycolysis via AMP-activated protein kinase (AMPK) phosphorylation. ALDOC was positively correlated with ADPGK, and high ALDOC expression was associated with worse survival outcomes in PCa.

CONCLUSIONS

In summary, ADPGK is a driving factor in PCa progression, and its high expression contributes to a poor prognosis in PCa patients. ADPGK accelerates PCa glycolysis and progression by activating ALDOC-AMPK signaling, suggesting that ADPGK might be an effective target and marker for PCa treatment and prognosis evaluation.

BMP-2-mediated signaling suppresses salivary gland development

Research regarding the process of salivary gland development and elucidation of related mechanisms are considered essential for development of effective treatments for conditions associated with salivary disease. Various reports regarding the effects of bone morphogenetic protein (BMP)-2 on hard tissue cells have been presented, though few have examined those related to salivary gland formation. Using an organ culture system, the present study was conducted to investigate the function of BMP-2 in salivary gland formation. Salivary glands obtained from embryonic day 13.5 mice and treated with BMP-2 showed suppression of primordial cell differentiation and also gland formation in a concentration-dependent manner. Furthermore, gland formation inhibition was suppressed by concurrent treatment with dorsomorphin, an inhibitor of the Smad pathway. Expression levels of AQP5, a marker gene for acinar cells, and Prol1, an opiorphin expressed in the lacrimal gland, were decreased in salivary glands treated with BMP-2. The present findings indicate that suppression of salivary gland formation, especially acinar differentiation, is induced by BMP-2, a phenomenon considered to be related to the Smad pathway.

Small-Molecule Probes as Pharmacological Tools for the Bone Morphogenetic Protein Signaling Pathway

The bone morphogenetic protein (BMP) pathway is highly conserved and plays central roles in health and disease. The quality and quantity of its signaling outputs are regulated at multiple levels, offering pharmacological options for targeted modulation. Both target-centric and phenotypic drug discovery (PDD) approaches were applied to identify small-molecule BMP inhibitors and stimulators. In this Review, we accumulated and systematically classified the different reported chemotypes based on their targets as well as modes-of-action, and herein we illustrate the discovery history of selected candidates. A comprehensive summary of available biochemical, cellular, and in vivo activities is provided for the most relevant BMP modulators, along with recommendations on their preferred use as chemical probes to study BMP-related (patho)physiological processes. There are a number of high-quality probes used as BMP inhibitors that potently and selectively interrogate the kinase activities of distinct type I (16 chemotypes available) and type II receptors (3 chemotypes available). In contrast, only a few high-quality BMP stimulator modalities have been introduced to the field due to a lack of profound target knowledge. FK506-derived macrolides such as calcineurin-sparing FKBP12 inhibitors currently represent the best-characterized chemical tools for direct activation of BMP-SMAD signaling at the receptor level. However, several PDD campaigns succeeded in expanding the druggable space of BMP stimulators. Albeit the majority of them do not entirely fulfill the strict chemical probe criteria, many chemotypes exhibit unique and unrecognized mechanisms as pathway potentiators or synergizers, serving as valuable pharmacological tools for BMP perturbation.

The tumour-promoting role of protein homeostasis: Implications for cancer immunotherapy

Protein homeostasis, an important aspect of cellular fitness that encompasses the balance of production, folding and degradation of proteins, has been linked to several diseases of the human body. Multiple interconnected pathways coordinate to maintain protein homeostasis within the cell. Recently, the role of the protein homeostasis network in tumorigenesis and tumour progression has gradually come to light. Here, we summarize the involvement of the most prominent components of the protein quality control mechanisms (HSR, UPS, autophagy, UPR and ERAD) in tumour development and cancer immunity. In addition, evidence for protein quality control mechanisms and targeted drugs is outlined, and attempts to combine these drugs with cancer immunotherapy are discussed. Altogether, combination therapy represents a promising direction for future investigations, and this exciting insight will be further illuminated by the development of drugs that can reach a balance between the benefits and hazards associated with protein homeostasis interference.

Optical Imaging Opportunities to Inspect the Nature of Cytosolic Iron Pools

The chemical nature of intracellular labile iron pools (LIPs) is described. By virtue of the kinetic lability of these pools, it is suggested that the isolation of such species by chromatography methods will not be possible, but rather mass spectrometric techniques should be adopted. Iron-sensitive fluorescent probes, which have been developed for the detection and quantification of LIP, are described, including those specifically designed to monitor cytosolic, mitochondrial, and lysosomal LIPs. The potential of near-infrared (NIR) probes for in vivo monitoring of LIP is discussed.

Reduced GS Domain Serine/Threonine Requirements of Fibrodysplasia Ossificans Progressiva Mutant Type I BMP Receptor ACVR1 in the Zebrafish

Fibrodysplasia ossificans progressiva (FOP) is a rare human genetic condition characterized by altered skeletal development and extraskeletal bone formation. All cases of FOP are caused by mutations in the type I bone morphogenetic protein (BMP) receptor gene ACVR1 that result in overactivation of the BMP signaling pathway. Activation of the wild-type ACVR1 kinase requires assembly of a tetrameric type I and II BMP receptor complex followed by phosphorylation of the ACVR1 GS domain by type II BMP receptors. Previous studies showed that the FOP-mutant ACVR1-R206H required type II BMP receptors and presumptive glycine/serine-rich (GS) domain phosphorylation for overactive signaling. Structural modeling of the ACVR1-R206H mutant kinase domain supports the idea that FOP mutations alter the conformation of the GS domain, but it is unclear how this leads to overactive signaling. Here we show, using a developing zebrafish embryo BMP signaling assay, that the FOP-mutant receptors ACVR1-R206H and -G328R have reduced requirements for GS domain phosphorylatable sites to signal compared to wild-type ACVR1. Further, ligand-independent and ligand-dependent signaling through the FOP-mutant ACVR1 receptors have distinct GS domain phosphorylatable site requirements. ACVR1-G328R showed increased GS domain serine/threonine requirements for ligand-independent signaling compared to ACVR1-R206H, whereas it exhibited reduced serine/threonine requirements for ligand-dependent signaling. Remarkably, while ACVR1-R206H does not require the type I BMP receptor partner, Bmpr1, to signal, a ligand-dependent GS domain mutant of ACVR1-R206H could signal independently of Bmpr1 only when Bmp7 ligand was overexpressed. Of note, unlike human ACVR1-R206H, the zebrafish paralog Acvr1l-R203H does not show increased signaling activity. However, in domain-swapping studies, the human kinase domain, but not the human GS domain, was sufficient to confer overactive signaling to the Acvr1l-R203H receptor. Together these results reflect the importance of GS domain activation and kinase domain functions in regulating ACVR1 signaling and identify mechanisms of reduced regulatory constraints conferred by FOP mutations. © 2023 American Society for Bone and Mineral Research (ASBMR).

O-GlcNAcylation of Raptor transduces glucose signals to mTORC1

The mechanistic target of rapamycin complex 1 (mTORC1) regulates metabolism and cell growth in response to nutrient levels. Dysregulation of mTORC1 results in a broad spectrum of diseases. Glucose is the primary energy supply of cells, and therefore, glucose levels must be accurately conveyed to mTORC1 through highly responsive signaling mechanisms to control mTORC1 activity. Here, we report that glucose-induced mTORC1 activation is regulated by O-GlcNAcylation of Raptor, a core component of mTORC1, in HEK293T cells. Mechanistically, O-GlcNAcylation of Raptor at threonine 700 facilitates the interactions between Raptor and Rag GTPases and promotes the translocation of mTOR to the lysosomal surface, consequently activating mTORC1. In addition, we show that AMPK-mediated phosphorylation of Raptor suppresses Raptor O-GlcNAcylation and inhibits Raptor-Rags interactions. Our findings reveal an exquisitely controlled mechanism, which suggests how glucose coordinately regulates cellular anabolism and catabolism.

Key separable events in the remodelling of the pharyngeal arches

The pharyngeal arches are a series of bulges on the lateral surface of the embryonic head. They are a defining feature of the most conserved, the phylotypic, stage of vertebrate development. In many vertebrate clades, the segmental arrangement of the pharyngeal arches is translated into the iterative anatomy of the gill arches. However, in amniotes the pharyngeal arches undergo a rearrangement during development and the segmental organisation of the pharynx is lost. This remodelling involves the expansion of the second arch which comes to overlie the more posterior arches. A transient sinus forms between the expanded second arch and the posterior arches, that is then lost, and the posterior arches are internalised. The morphogenesis of the second arch has been viewed as being central to this remodelling. Yet little is known about this process. Therefore, in this study, we have characterised the development of the second arch. We show that as the second arch expands, its posterior margin forms a leading edge and that the mesenchymal cells subjacent to this are in an elevated proliferative state. We further show that the posterior marginal epithelium is the site of expression of three key developmental signalling molecules: BMP7, FGF8 and SHH, and that their expression continues throughout the period of expansion. Using a novel approach, we have been able to simultaneously inhibit these three pathways, and we find that when this is done the second arch fails to establish its caudal projection and that there is a loss of proliferation in the posterior mesenchymal cells of the second arch. We have further used this manipulation to ask if the internalisation of the posterior arches is dependent upon the expansion of the second arch. We find that it is not-the posterior arches are still internalised when the expansion of the second arch is curtailed. We further show that while the collapse of the sinus is dependent upon thyroid hormone signalling, that this is not the case for the internalisation of the posterior pouches. Thus, the internalisation of the posterior arches is not dependent on the expansion of the second arch or on the collapse of the sinus. Finally, we show that the termination of expansion of the second arch correlates with a burst of morphogenetic cell death suggesting a mechanism for ending this. Thus, while it has long been thought that it is the morphogenesis of the second arch that drives the remodelling of the pharyngeal arches, we show that this is not the case. Rather the remodelling of the pharyngeal arches is a composite process that can split into contemporaneous but separate events: the expansion of the second arch, the internalisation of the posterior arches and the collapse of the sinus.

An Efficient 2D Protocol for Differentiation of iPSCs into Mature Postmitotic Dopaminergic Neurons: Application for Modeling Parkinson's Disease

About 15% of patients with parkinsonism have a hereditary form of Parkinson's disease (PD). Studies on the early stages of PD pathogenesis are challenging due to the lack of relevant models. The most promising ones are models based on dopaminergic neurons (DAns) differentiated from induced pluripotent stem cells (iPSCs) of patients with hereditary forms of PD. This work describes a highly efficient 2D protocol for obtaining DAns from iPSCs. The protocol is rather simple, comparable in efficiency with previously published protocols, and does not require viral vectors. The resulting neurons have a similar transcriptome profile to previously published data for neurons, and have a high level of maturity marker expression. The proportion of sensitive (SOX6+) DAns in the population calculated from the level of gene expression is higher than resistant (CALB+) DAns. Electrophysiological studies of the DAns confirmed their voltage sensitivity and showed that a mutation in the PARK8 gene is associated with enhanced store-operated calcium entry. The study of high-purity DAns differentiated from the iPSCs of patients with hereditary PD using this differentiation protocol will allow for investigators to combine various research methods, from patch clamp to omics technologies, and maximize information about cell function in normal and pathological conditions.

Dual mechanism underlying failure of neural tube closure in the Zic2 mutant mouse

Understanding the molecular mechanisms that lead to birth defects is an important step towards improved primary prevention. Mouse embryos homozygous for the Kumba (Ku) mutant allele of Zic2 develop severe spina bifida with complete lack of dorsolateral hinge points (DLHPs) in the neuroepithelium. Bone morphogenetic protein (BMP) signalling is overactivated in Zic2Ku/Ku embryos, and the BMP inhibitor dorsomorphin partially rescues neural tube closure in cultured embryos. RhoA signalling is also overactivated, with accumulation of actomyosin in the Zic2Ku/Ku neuroepithelium, and the myosin inhibitor Blebbistatin partially normalises neural tube closure. However, dorsomorphin and Blebbistatin differ in their effects at tissue and cellular levels: DLHP formation is rescued by dorsomorphin but not Blebbistatin, whereas abnormal accumulation of actomyosin is rescued by Blebbistatin but not dorsomorphin. These findings suggest a dual mechanism of spina bifida origin in Zic2Ku/Ku embryos: faulty BMP-dependent formation of DLHPs and RhoA-dependent F-actin accumulation in the neuroepithelium. Hence, we identify a multi-pathway origin of spina bifida in a mammalian system that may provide a developmental basis for understanding the corresponding multifactorial human defects.

Small-Molecule-Mediated Suppression of BMP Signaling by Selective Inhibition of BMP1-Dependent Chordin Cleavage

BMP signaling is critical for many biological processes. Therefore, small molecules that modulate BMP signaling are useful for elucidating the function of BMP signaling and treating BMP signaling-related diseases. Here, we performed a phenotypic screening in zebrafish to examine the in vivo effects of N-substituted-2-amino-benzoic acid analogs NPL1010 and NPL3008 and found that they affect BMP signaling-dependent dorsal-ventral (D-V) patterning and bone formation in zebrafish embryos. Furthermore, NPL1010 and NPL3008 suppressed BMP signaling upstream of BMP receptors. BMP1 cleaves Chordin, an antagonist of BMP, and negatively regulates BMP signaling. Docking simulations demonstrated that NPL1010 and NPL3008 bind BMP1. We found that NPL1010 and NPL3008 partially rescued the disruptions in the D-V phenotype caused by bmp1 overexpression and selectively inhibited BMP1-dependent Chordin cleavage. Therefore, NPL1010 and NPL3008 are potentially valuable inhibitors of BMP signaling that act through selective inhibition of Chordin cleavage.

Discovery of Highly Potent and BMPR2-Selective Kinase Inhibitors Using DNA-Encoded Chemical Library Screening

The discovery of monokinase-selective inhibitors for patients is challenging because the 500+ kinases encoded by the human genome share highly conserved catalytic domains. Until now, no selective inhibitors unique for a single transforming growth factor β (TGFβ) family transmembrane receptor kinase, including bone morphogenetic protein receptor type 2 (BMPR2), have been reported. This dearth of receptor-specific kinase inhibitors hinders therapeutic options for skeletal defects and cancer as a result of an overactivated BMP signaling pathway. By screening 4.17 billion "unbiased" and "kinase-biased" DNA-encoded chemical library molecules, we identified hits CDD-1115 and CDD-1431, respectively, that were low-nanomolar selective kinase inhibitors of BMPR2. Structure-activity relationship studies addressed metabolic lability and high-molecular-weight issues, resulting in potent and BMPR2-selective inhibitor analogs CDD-1281 (IC50 = 1.2 nM) and CDD-1653 (IC50 = 2.8 nM), respectively. Our work demonstrates that DNA-encoded chemistry technology (DEC-Tec) is reliable for identifying novel first-in-class, highly potent, and selective kinase inhibitors.

Proteomes from AMPK-inhibited peripheral blood mononuclear cells suppress the progression of breast cancer and bone metastasis

Background: During a developmental process, embryos employ varying tactics to remove unwanted cells. Using a procedure analogous to some of the embryonic cells, we generated a tumor-eliminating conditioned medium (CM) from AMPK-inhibited lymphocytes and monocytes in peripheral blood mononuclear cells (PBMCs). Methods: AMPK signaling was inhibited by the application of a pharmacological agent, Dorsomorphin, and the therapeutic effects of their conditioned medium (CM) were evaluated using in vitro cell cultures, ex vivo breast cancer tissues, and a mouse model of mammary tumors and tumor-induced osteolysis. The regulatory mechanism was evaluated using mass spectrometry-based proteomics, Western blotting, immunoprecipitation, gene overexpression, and RNA interference. Results: While AMPK signaling acted mostly anti-tumorigenic, we paradoxically inhibited it to build induced tumor-suppressing cells and their tumor-eliminating CM. In a mouse model of breast cancer, the application of AMPK-inhibited lymphocyte-derived CM reduced mammary tumors additively to a chemotherapeutic agent, Taxol. It also prevented bone loss in the tumor-bearing tibia. Furthermore, the application of CM from the patient-derived peripheral blood diminished ex vivo breast cancer tissues isolated from the same patients. Notably, proteins enriched in CM included Moesin (MSN), Enolase 1 (ENO1), and polyA-binding protein 1 (PABPC1), which are considered tumorigenic in many types of cancer. The tumor-suppressing actions of MSN and ENO1 were at least in part mediated by Metadherin (Mtdh), which is known to promote metastatic seeding. Conclusion: We demonstrated that PBMCs can be used to generate tumor-suppressive proteomes, and extracellular tumor-suppressing proteins such as MSN, ENO1, and PABPC1 are converted from tumor-promoting factors inside cancer cells. The results support the possibility of developing autologous blood-based therapy, in which tumor-suppressing proteins are enriched in engineered PBMC-derived CM by the inhibition of AMPK signaling.

Zebrafish as a Mainstream Model for In Vivo Systems Pharmacology and Toxicology

Pharmacology and toxicology are part of a much broader effort to understand the relationship between chemistry and biology. While biomedicine has necessarily focused on specific cases, typically of direct human relevance, there are real advantages in pursuing more systematic approaches to characterizing how health and disease are influenced by small molecules and other interventions. In this context, the zebrafish is now established as the representative screenable vertebrate and, through ongoing advances in the available scale of genome editing and automated phenotyping, is beginning to address systems-level solutions to some biomedical problems. The addition of broader efforts to integrate information content across preclinical model organisms and the incorporation of rigorous analytics, including closed-loop deep learning, will facilitate efforts to create systems pharmacology and toxicology with the ability to continuously optimize chemical biological interactions around societal needs. In this review, we outline progress toward this goal.

Ironing out macrophages in atherosclerosis

<p indent="0mm">The most common cause of death worldwide is atherosclerosis and related cardiovascular disorders. Macrophages are important players in the pathogenesis of atherosclerosis and perform critical functions in iron homeostasis due to recycling iron by phagocytosis of senescent red blood cells and regulating iron availability in the tissue microenvironment. With the growth of research on the "iron hypothesis" of atherosclerosis, macrophage iron has gradually become a hotspot in the refined iron hypothesis. Macrophages with the M1, M2, M(Hb), Mox, and other phenotypes have been defined with different iron-handling capabilities related to the immune function and immunometabolism of macrophages, which influence the progression of atherosclerosis. In this review, we focus on macrophage iron and its effects on the development of atherosclerosis. We also cover the contradictory discoveries and propose a possible explanation. Finally, pharmaceutical modulation of macrophage iron is discussed as a promising target for atherosclerosis therapy.</p>.

Modeling leukemia with zebrafish (Danio rerio): Towards precision medicine

Leukemia is a type of blood cancer characterized by high genetic heterogeneity and fatality. While chemotherapy remains the primary form of treatment for leukemia, its effectiveness was profoundly diminished by the genetic heterogeneity and cytogenetic abnormalities of leukemic cells. Therefore, there is an unmet need to develop precision medicine for leukemia with distinct genetic backgrounds. Zebrafish (Danio rerio), a freshwater fish with exceptional feasibility in genome editing, is a powerful tool for rapid human cancer modeling. In the past decades, zebrafish have been adopted in modeling human leukemia, exploring the molecular mechanisms of underlying genetic abnormalities, and discovering novel therapeutic agents. Although many recurrent mutations of leukemia have been modeled in zebrafish for pathological study and drug discovery, its great potential in leukemia modeling was not yet fully exploited, particularly in precision medicine. In this review, we evaluated the current zebrafish models of leukemia/pre-leukemia and genetic techniques and discussed the potential of zebrafish models with novel techniques, which may contribute to the development of zebrafish as a disease model for precision medicine in treating leukemia.

Stepwise synthesis of 2,6-difunctionalized ethyl pyrazolo[1,5-a]pyrimidine-3-carboxylate via site-selective cross-coupling reactions: experimental and computational studies

A variety of novel disubstituted 2-(alknyl, aryl and arylamine)-6-alkynylpyrazolo[1,5-a]pyrimidine derivatives was prepared via sequential site-selective cross-coupling reactions from 2,6-dibromopyrazolo[1,5-a]pyrimidine 3. The regio-controlled Sonogashira-type coupling of 3 with a wide range of terminal alkynes proceeded smoothly with excellent selectivity in favor of the C6-position through careful adjustment of the coupling conditions, followed by the subsequent introduction of alkynyl, aryl or arylamine groups at the C2-position via the Sonogashira, Suzuki-Miyaura and Buchwald-Hartwig coupling reactions, respectively. These promising results allow for further use and diversification of the chemically and biologically interesting pyrazolo[1,5-a]pyrimidine scaffold. In addition, computational studies were conducted to provide explanations for the origin of regioselectivity.