Search Results (351)

Follistatin (FST) binds to and neutralizes members of the transforming growth factor-beta (TGF-β) superfamily, thereby regulating diverse physiological processes, including regulation of skeletal muscle, adipose, and bone homeostasis. FST also promotes adipose browning and enhances energy metabolism, leading to improved plasma lipid profiles and metabolic health in mice. Given the emerging association between brown adipose tissue (BAT) activation and reduced atherosclerosis, we investigated the anti-atherogenic potential of FST. Transcriptomic and metabolomic analyses of the Hybrid Mouse Diversity Panel (HMDP) revealed that Fst expression was negatively correlated with aortic lesion area and positively correlated with the expression of multiple adipose browning-associated genes. Adeno-associated viral delivery of Fst (AAV1-FST344) in Ldlr^−/− mice significantly reduced aortic lesion area, improved plasma lipid profiles, and decreased expression of adhesion (VCAM1) and inflammatory (iNOS, TNF-α) markers in white adipose tissue (WAT), liver, and heart. Fst gene delivery also markedly increased uncoupling protein 1 (UCP1) expression in WAT, consistent with WAT browning. Integrated correlation analyses of Fst expression with tissue metabolites, together with plasma metabolite–lesion associations identified in the HMDP, implicated the arginase 1 (Arg1)-mediated metabolic pathway as a key regulator of atherogenesis. Consistent with these findings, Arg1 expression was significantly elevated in WAT, liver, and heart of AAV1-FST344-treated mice and in wild-type versus Fst-knockout mouse embryonic fibroblasts (MEFs). Immunostaining localized Arg1 predominantly to CD68⁺ macrophages in heart and liver. Given recent evidence identifying Arg1 as a novel mediator of efferocytosis, these findings suggest that Arg1 may promote macrophage metabolic reprogramming and resolution of inflammation by enhancing the clearance of apoptotic cells. Furthermore, Fst gene delivery increased the expression of fibroblast growth factor 21 (Fgf21) and adiponectin (AdipoQ) in WAT. Collectively, these findings identify Fst as a novel anti-atherogenic regulator that protects against vascular disease by promoting adipose browning, improving lipid metabolism, and activating Arg1-mediated metabolic pathways. Full article

Cisplatin (CP) chemotherapy is limited by nephrotoxicity, primarily involving tubular epithelial cell apoptosis. αB-crystallin (CryAB) is a small heat shock protein that plays a cytoprotective role in stressed kidneys but can also promote tumor progression. Its precise role and molecular mechanisms in CP-induced kidney injury remain largely unclear. This study highlighted the function of CryAB and its regulatory pathways in CP nephrotoxicity by employing in vitro models of rat renal tubular epithelial cells (NRK-52E) with CryAB gene knockdown/overexpression, and in vivo models of CryAB knockout/wild-type mice, followed by CP treatment. Apoptosis and key signaling pathways (NF-κB, MAPK, AKT) were evaluated in this study. The results indicated that CP treatment (20 µM) significantly upregulated CryAB expression in renal cells (p < 0.01) and triggered both apoptosis and MAPK activation. CryAB deficiency sensitized cells and mice to CP, exacerbating renal dysfunction, tubular injury, and apoptosis, as evidenced by increased Bax, cyt c release, and caspase-3 cleavage. Conversely, CryAB overexpression attenuated these effects. Furthermore, our findings suggest that the lack of CryAB favors the cytoplasmic retention of NF-κB, and that CryAB status can influence MAPK signaling, pointing to a potential regulatory loop. Additionally, CP-induced AKT phosphorylation was diminished in CryAB-deficient models. Therefore, CryAB may exert a cytoprotective role in CP nephrotoxicity, potentially mitigating tubular apoptosis by modulating the mitochondrial apoptotic pathway, supporting NF-κB-mediated survival signaling, and cross-talking with MAPK and AKT pathways. Our findings suggest that CryAB serves as an important regulator of renal cell fate and a potential therapeutic target for mitigating CP-induced kidney injury. Full article

Imiquimod-induced skin inflammation is the most widely used psoriasis mouse model. Although p38 mitogen-activated protein kinase reportedly plays a role in the pathogenesis of psoriatic inflammation, the purpose of one of its upstream activators, apoptosis signal-regulating kinase 1 (ASK1), remains unclear. This study investigated the role of ASK1 and its molecular mechanism in the imiquimod-induced psoriasis model. Compared to wild-type mice, the ASK1 knockout (KO) mouse skin lesion showed a higher clinical score and a thicker epidermis. The mRNA expression of pro-inflammatory cytokines, such as IL-17 and TNF-α, was also higher. Notably, the expression of aryl hydrocarbon receptor (AhR), a sensor for xenobiotic chemicals that is expressed in the skin to strengthen the skin barrier and accelerate terminal differentiation of the epidermis—as well as its downstream molecule CYP1A1, but not NRF2—was increased in the ASK1 KO psoriatic skin lesion. Immunoprecipitation analysis, followed by Western blotting, revealed that ASK1 interacts with AhR in cells transfected with their respective expression vectors, potentially leading to reduced AhR expression. These results suggest that ASK1 negatively regulates the development of the imiquimod-induced mouse psoriasis model by interacting with AhR and presumably antagonizing the AhR-CYP1A1 axis. Full article

Background/Objectives: Clear cell renal cell carcinoma (ccRCC) is the most common form of kidney cancer. Human ccRCCs have increased glycolytic metabolism and decreased mitochondrial oxidative metabolism relative to normal kidneys. Our research using human RCC4 ccRCC cells and a murine model of ccRCC, TRACK (TRAnsgenic model/Cancer/Kidney), in which a triple-mutant (P402A, P564A, N803A) human HIF1α is selectively expressed in proximal tubule cells (PTCs), revealed highly induced ATF4, a stress-responsive transcription factor. We then investigated the role of ATF4 in the metabolic changes in ccRCC. Methods: We performed comprehensive analysis of the ccRCC Cancer Genomics Atlas (TCGA) data. We deleted ATF4 in PTCs of TRACK mice and human RCC4 cells. We conducted genome-wide transcriptomic and untargeted metabolomic studies of cortices of WT and CGERA∆T (TRACK mice with PTC-specific ATF4-knockout (KO)) mice and performed glucose isotopologue tracing in parental and ATF4 KO RCC4 cells. Results: Analysis of TCGA data showed increased mRNAs of enzymes in glycolysis and reduced mRNAs of enzymes in the TCA cycle. Transcriptomic and metabolomic studies demonstrated that ATF4 deletion suppressed glycolysis and enhanced TCA cycle metabolism in CGERA∆T versus WT cortices. Glucose isotopologue tracing showed that ATF4 deletion altered glycolysis pathway metabolite levels and shifted glucose metabolism towards the TCA cycle, evidenced by increased intracellular [¹³C₂]citrate in RCC4-ATF4 KO cells. Using the Seahorse XFe96 analyzer we also showed reduced glycolytic capacity and reserve in RCC4-ATF4 KO cells. Conclusions: Collectively, our results demonstrate that ATF4 regulates glycolysis in ccRCC, supporting ATF4 as a therapeutic target. Full article

To investigate the neural circuit mechanisms linking the physiological loss of α-synuclein (α-syn) function to depressive-like states, we explored whether constitutive α-syn depletion disrupts the excitation and inhibition balance within the medial prefrontal cortex. We integrated comprehensive behavioral paradigms, whole-cell patch-clamp electrophysiology, and targeted chemogenetics within an α-syn knockout mouse model. Behavioral profiling revealed that α-syn deficiency was accompanied by basal psychomotor hyperactivity and profound stress-coping deficits. Cellular electrophysiology in the medial prefrontal cortex demonstrated a significantly enhanced intrinsic excitability across both GABAergic and glutamatergic populations. Furthermore, targeted chemogenetic suppression of GAD67-positive interneurons partially alleviated the depressive-like phenotype without confounding baseline locomotion. In summary, the physiological depletion of endogenous α-syn is associated with altered stress-coping behaviors and increased mPFC neuronal excitability. Chemogenetic suppression of mPFC GAD67-positive interneurons partially reduces immobility in SYN-KO mice, implicating prefrontal inhibitory circuit dysregulation in these behavioral alterations. These findings underscore the importance of α-syn homeostasis in modulating cortical microcircuits and provide novel insights into the early non-motor manifestations of synucleinopathies. Full article

Diabetic kidney disease (DKD) is a primary cause of end-stage renal disease (ESRD), and while ferroptosis is known to contribute to DKD pathogenesis, the regulatory role of the NLRP3 inflammasome in this process remains elusive. To address this research gap, we explored whether NLRP3 inhibition alleviates DKD by suppressing ferroptosis using streptozotocin-induced diabetic wild-type and NLRP3-knockout C57BL/6 mice, alongside high-glucose-cultured (30 mM) human renal tubular epithelial (HK-2) cells with or without siNLRP3 transfection. Inflammatory cytokines (IL-6, TNF-α, and IL-1β) were measured using an ELISA; oxidative stress markers (CSSG, MDA, GSH, and ROS) and the iron ion content via colorimetric assays; mitochondrial morphology by transmission electron microscopy (TEM); and ferroptosis-related proteins (ACSL4, COX2, and GPX4) through Western blotting. Our findings demonstrate that NLRP3-knockout diabetic mice displayed markedly reduced urinary albumin excretion and serum creatinine levels (p < 0.01) compared with wild-type diabetic controls, concurrent with suppressed renal iron overload and ferroptosis, diminished inflammatory cytokine levels, and attenuated oxidative stress. Pathological assessments further revealed ameliorated renal fibrosis and preserved mitochondrial ultrastructure in NLRP3-deficient mice. In vitro, siNLRP3 transfection abrogated high-glucose-induced inflammation, oxidative stress, and ferroptosis in HK-2 cells, effects that were reversed by the ferroptosis inducer erastin (p < 0.01). Mechanistically, NLRP3 deficiency was associated with upregulated GPX4 expression and downregulated ACSL4 and COX2 expression. Collectively, these results indicate that inhibition of the NLRP3 inflammasome mitigates DKD progression by suppressing ferroptosis, underscoring its translational potential as a therapeutic target for this condition. Full article

Background: Inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn’s disease (CD), increase colorectal cancer (CRC) risk. Methods: Mouse IBD and CRC models with a combination of pharmacological, knockout and knock-in approaches was employed to analyze the involvement of TOP2s and NOS2 in CRC tumorigenesis. Key pathologies, such as inflammatory and neoplastic scores, were examined by immunohistochemical assays. Results: In colon tissues from acute, chronic colitis and CRC mouse models and from CD patients, the biomarkers γH2AX and 53BP1_pS25/S29 of DNA breaks (mainly representing DSBs) accumulated, alongside increases in topoisomerase II (TOP2) and nitric oxide synthase 2 (NOS2). Genetic ablation of NOS2 (Nos2^-/-) or TOP2β (Top2β^f/f) as well as pharmacological inhibition with ICRF-193 (a TOP2 inhibitor) or PTIO (a NO scavenger) reduced DSB formation and disease severity. Consistently, Nos2^-/-, or ICRF-treated, mice exhibited decreased tumor burden. DSBs and tumor accumulation were pronounced in the distal colon, mirroring human CRC distribution. While ICRF-193 suppressed tumor growth, Top2β^f/f deficiency (with a compensatory TOP2α upregulation) enhanced tumor development, indicating potential roles for TOP2 isozymes in tumor formation and progression. Conclusion: Collectively, these findings identify the cooperative action of TOP2 and NOS2 in driving DSBs, highlighting a potential therapeutic target in inflammation-associated CRC. Full article

Latrophilin 1 (LPHN1/ADGRL1), an adhesion G-protein-coupled receptor (GPCR), is the principal receptor for α-latrotoxin (αLTX), a toxin that triggers massive neurotransmitter release. However, its endogenous signaling mechanism remains elusive. Here, we dissect the LPHN1 signaling pathway at the vertebrate neuromuscular junction, using the pore-deficient αLTX mutant LTX^N4C as a selective agonist. Combining electrophysiological recordings from LPHN1 knockout mice with pharmacological inhibitors, calcium imaging, and biochemical assays, we delineate the cascade from receptor activation to spontaneous quantal acetylcholine release. We demonstrate that LPHN1 is specifically localized to the presynaptic membrane and mediates LTX^N4C-evoked release. Upon activation, LPHN1 engages the G_αq–phospholipase C pathway to generate inositol 1,4,5-trisphosphate (IP₃), triggering Ca²⁺ release from intracellular stores via IP₃ receptors. This store depletion activates store-operated Ca²⁺ entry (SOCE), providing sustained Ca²⁺ required for LTX^N4C-induced burst-like exocytosis. We uncover distinct roles for Ca_V2.1 and Ca_V1 channels in initiating and sustaining this response. These findings establish LPHN1 as a GPCR that harnesses intracellular stores and SOCE to drive spontaneous neurotransmission, revealing a novel signaling paradigm for adhesion GPCRs in presynaptic function. Full article

In recent years, significant progress has been made in understanding that Parkinson’s disease (PD) is associated not only with the dopamine (DA) but also with the norepinephric (NE) system. In order to investigate the potential involvement of NE in the development of the early motor symptoms of PD, we studied the effects of reducing its levels in a norepinephrine transporter knockout mouse (NET-KO). Due to the absence of NET, all the norepinephrine needed must be synthesized de novo. NET-KO mice were injected intraperitoneally with α-methyl-p-tyrosine (AMPT), a blocker of tyrosine hydroxylase, to induce a hyponoradrenergic state. Changes in tissue NE content in the frontal cortex and DA content in the striatum were evaluated using HPLC. We also measured the motor activity parameters of NET-KO mice after AMPT injection. The hyponorepinephric state induced by AMPT administration in NET-KO mice did not lead to severe motor impairments, as occurs in PD models. However, NET-KO mice did exhibit abnormal hindlimb extension, which began three hours after AMPT administration. This symptom may be interpreted as an early symptom preceding PD. These results suggest that the potential involvement of different neurotransmitter systems in motor abnormalities relevant to Parkinson’s disease warrants further investigation. Full article

Betaine-homocysteine methyltransferase (BHMT) is an enzyme involved in one-carbon metabolism and plays a crucial role in maintaining liver health. In this study, we investigated the impact of liver-specific deletion of BHMT on liver dysfunction using a mouse model. We generated BHMT floxed mice and bred them with albumin Cre to generate liver-specific BHMT knockout (BHMT LKO) mice. Liver tissues harvested from six-month-old chow-fed BHMT floxed and LKO mice were characterized through histological, biochemical, and molecular analyses. BHMT LKO mice displayed a complete loss of hepatic expression of BHMT mRNA, protein and enzyme activity. Histopathological analysis revealed the development of hepatic steatosis in BHMT LKO mice compared to the floxed mice. These morphological changes were supported by biochemical analysis showing elevated levels of hepatic triglycerides in conjunction with a profound decrease in the methylation potential (i.e., reduced S-adenosylmethionine (SAM): S-adenosylhomocysteine (SAH) ratio), which was mainly driven by a six- to sevenfold increase in SAH levels. BHMT LKO mice also exhibited increased lipid peroxidation and lysosomal dysfunction compared to floxed mice. Early signs of inflammation were seen in the livers of BHMT LKO mice of both sexes, as evident from significant increase in CD68-positive cells and interleukin 1β levels. Additionally, there was a moderate increase in fibrosis, as evidenced by the upregulated expression of α-smooth muscle actin and collagen II levels and the histological assessment of picrosirius red-stained liver sections of BHMT LKO mice of both sexes compared to their respective counterparts. These findings demonstrate that hepatic BHMT deficiency promotes lipid accumulation, lysosomal/proteasomal dysfunction, and early inflammatory and fibrotic changes in the liver by reducing the methylation potential. Collectively, our results underscore BHMT as a critical regulator of liver homeostasis and a potential therapeutic target in liver-related disorders. Full article

Parkinson’s disease (PD) is a common neurodegenerative disorder marked by progressive loss of dopaminergic neurons in the substantia nigra pars compacta and the accumulation of Lewy bodies, intracellular inclusions enriched in α-synuclein. Synphilin-1 interacts with α-synuclein, localizes to Lewy bodies, and has been implicated in inclusion formation and neuroprotection in cellular and animal models; however, its physiological function in vivo remains poorly defined. Here, we generated and characterized a synphilin-1 knockout (Sph-1 KO) mouse by targeted genetic deletion of the Sph-1 locus and performed a comprehensive phenotyping battery including behavioral testing as well as biochemical, histological, structural, and ultrastructural analyses. Sph-1 KO mice survived to nearly two years of age and showed normal body weight, lifespan, motor performance, learning and memory, anxiety-like behavior, attention, and gross brain morphology. Western blot analyses indicated that levels of α-synuclein and synaptic proteins were largely unchanged. While outer mitochondrial membrane proteins were unaffected, the mitochondrial matrix protein HSP60 was reduced, consistent with altered mitochondrial proteostasis in the absence of synphilin-1. Strikingly, histochemical analyses, magnetic resonance imaging, and electron microscopy revealed early-onset hydrocephalus in Sph-1 KO mice associated with severe loss and disorganization of motile ependymal cilia in the ventricular lining, a cell type that normally expresses high levels of synphilin-1. Ultrastructural and immunohistochemical analyses revealed disrupted ependymal architecture, mislocalization of acetylated α-tubulin to the cytoplasm, cellular swelling, and enlarged, aberrant mitochondria, whereas cortical neurons appeared largely structurally unaffected. Together, these findings identify synphilin-1 as a key regulator of microtubule organization and cytoskeletal/organelle homeostasis in ependymal cells, required to maintain motile ciliogenesis, cerebrospinal fluid flow, and ventricular integrity. This unexpected role for synphilin-1 in ciliated brain epithelia, along with a reduction in the critical mitochondrial chaperone HSP60, broadens our understanding of synphilin-1 biology and provides a new framework for its potential relevance to PD-associated pathology. Full article

Ultraviolet B (UVB), as a major component of solar radiation, is a key factor in inducing skin photoaging. The epidermis serves as the primary defensive barrier of the skin and absorbs the majority of UVB. This study aims to elucidate the protective effect of Alk against UVB-induced photoaging and further uncover its underlying molecular mechanisms. In vitro, Alk-pretreated HaCaT cells were exposed to UVB. Cell viability, ROS, senescence, antioxidant enzymes, and protein expression were analyzed. Mechanisms were examined using CETSA, DARTS, Co-IP, and NRF2 knockout. In vivo, Alk hydrogel was tested in UVB-exposed BALB/c mice, with protection assessed via histology and immunohistochemistry. In vitro, Alk directly binds to Keap1, disrupts Keap1–Nrf2 interaction, promotes nuclear translocation of Nrf2, and upregulates the expression of its downstream target HO-1. Consequently, intracellular ROS generation is reduced, cellular senescence is alleviated, and the expression of inflammatory factors (TNF-$\alpha$, COX-2) and MMP-9 is suppressed. In vivo, topical application of the Alk hydrogel prevented UVB-induced skin thickening and collagen degradation. Alk exerts a preventive effect on UVB-induced photoaging in HaCaT cells and skin, providing strong support for developing Alk as a potential plant-derived active ingredient for preventing skin photoaging. Full article

Interleukin (IL)-1β is a pro-inflammatory cytokine implicated in sterile inflammation and tumor development. Investigating the role of MAPKAP kinase 2 (MK2) in IL-1β processing, we found that Il1b mRNA and IL-1β protein levels were elevated in resting MK2-knockout (KO) macrophages and in the serum of MK2/3 double-KO mice. This was linked to activation of the non-canonical NF-κB pathway in the absence of MK2 or its activator, p38α. Rescue by MK2, its kinase-inactive mutant MK2K79R, or p38α suppressed this pathway and reduced Il1b expression. We also observed decreased basal protein levels of tumor suppressor p53 in MK2- or p38α-deficient cells. Mechanistically, p53 interacts with caspase-3, promoting cleavage of RelB, thereby inhibiting non-canonical NF-κB signaling and subsequent Il1b and TP53 expression. These findings explain elevated basal IL-1β levels in MK2-KO macrophages and uncover a new autoregulatory mechanism of TP53 expression. Additionally, they reveal a new mechanism that contributes to the long-discussed link between cancer and inflammation, wherein the tumor suppressor p53 inhibits cytokine production in parallel. Full article

Long-term nutritional excess causes hepatic steatosis, endoplasmic reticulum (ER) stress, hyperglycemia, and hyperlipidemia. Mitogen-activated protein kinase phosphatase-3 (MKP-3) is a well-established stress-regulated protein and a regulator of gluconeogenesis. Our previous study revealed that acute ER stress reduced gluconeogenesis and MKP-3 protein stability. However, the expression of MKP-3 and its regulatory mechanisms in chronic ER stress remain unclear. The aim of this study was to investigate the effects of chronic ER stress on hepatic MKP-3 expression and its role in the regulation of gluconeogenesis. The results show that long-term administration of thapsigargin (Tg) or palmitic acid promoted gene expression of Mkp-3 and gluconeogenic genes Pepck, G6pc, and Pgc1α in primary mouse hepatocytes. In addition, a long-term high-fat diet (HFD) or Tg administration significantly increased hepatic ER stress and blood glucose level in mice, while inducing the expression of Mkp-3 and hepatic gluconeogenic genes Pepck, G6pc and Pgc1α. Further study revealed that liver-specific Mkp-3 knockout (Mkp-3 LKO) reversed the blood glucose level and expression levels of gluconeogenic genes those were induced by long-term HFD in mice. Moreover, activation of the PKR-like ER kinase (PERK) by its agonist increased hepatic Mkp-3 expression, whereas inhibitor of PERK suppressed the expression of Mkp-3 under Tg administration. These results suggest that chronic high-fat diet might promote hepatic gluconeogenesis via the PERK/MKP-3 pathway. Consequently, this study identified a potential therapeutic target for treating obesity-related hyperglycemia. Full article

Skin fibrosis is characterized by excessive extracellular matrix (ECM) deposition, leading to tissue dysfunction and scarring. Transforming growth factor (TGF)-β is a central mediator of fibrosis. We previously identified CD109 as a TGF-β co-receptor and negative regulator of TGF-β signaling and fibrotic responses and showed that its epidermal overexpression reduces dermal fibrosis in vivo. However, the effects of CD109 loss in the dermis remain unclear. The current study investigates the impact of CD109 knockout (KO) on skin fibrosis using a bleomycin-induced fibrosis mouse model. Following bleomycin treatment, CD109 KO mice showed increased collagen I deposition and elevated fibronectin, CCN2, and α–smooth muscle actin expression in the skin, indicating enhanced ECM production and myofibroblast differentiation compared with wild-type mice. Additionally, CD109 KO mice displayed enhanced Smad1 and Smad2/3 phosphorylation in the skin, indicating heightened TGF-β signaling. In vitro, CD109 KO fibroblasts exhibited increased TGF-β-induced migration and collagen contraction. These findings suggest that CD109 deficiency exacerbates dermal fibrosis by promoting TGF-β/Smad signaling and myofibroblast activation. Given its dysregulation in fibrotic disorders such as scleroderma, our results identify CD109 as a key regulator of skin homeostasis by modulating ECM production and fibroblast activation, underscoring its potential as a therapeutic target in fibrotic disorders. Full article