Bovine viral diarrhea virus (BVDV) is a critical pathogen affecting the global cattle industry, causing severe economic losses primarily through persistent infection, immunosuppression, and reproductive failure. The virus exhibits substantial genetic diversity, with marked geographic variation in circulating subtypes, which complicates effective disease control. BVDV evades host immune responses by suppressing type I interferon signaling, impairing neutrophil function, and reprogramming host cellular metabolism, ultimately leading to the generation of persistently infected (PI) animals that serve as the principal reservoir for viral transmission. Current prevention and control strategies rely mainly on the identification and elimination of PI animals in combination with vaccination. However, conventional vaccines, including inactivated vaccines (IVs) and modified live vaccines (MLVs), have notable limitations, such as suboptimal subtype matching, interference by maternal antibodies, and safety concerns associated with MLV use in pregnant cattle. Emerging vaccine platforms, including mRNA vaccines, subunit vaccines, and multi-epitope vaccines, offer promising alternatives owing to their improved safety profiles, rapid design and production, and potential to elicit broad and robust immune responses. Future BVDV vaccine development should integrate artificial intelligence-driven design strategies with high-throughput sequencing and molecular epidemiological surveillance to enable the rational development of multivalent and multi-epitope vaccines. In addition, coordinated implementation of strain monitoring, PI animal clearance, and enhanced biosecurity practices will be essential for establishing a comprehensive and sustainable BVDV prevention and control framework.

Skeletal muscle lipid metabolic homeostasis is essential for normal function and physical performance. Ubiquitin-fold modifier 1 ligase 1 (UFL1), the sole E3 ligase in the UFMylation system, is widely involved in lipid metabolism across various cell types, yet its specific role in skeletal muscle remains unclear. Using skeletal muscle-specific UFL1 knockout mice and UFL1-manipulated C2C12 cells, we found that UFL1 deficiency led to marked lipid droplet accumulation, elevated triglyceride (TG) and total cholesterol (TCH) levels, and upregulation of the lipid droplet coat protein perilipin 2 (PLIN2), whereas UFL1 overexpression reversed these effects. Mechanistically, expression of the lipogenic enzymes acetyl-CoA carboxylase 1 (ACC1) and fatty acid synthase (FASN) was significantly increased in UFL1-deficient tissues and cells, whereas protein levels of peroxisome proliferator-activated receptor alpha (PPARα) and its downstream target carnitine palmitoyltransferase 1A (CPT1A) remained unchanged, effects reversed by UFL1 overexpression. Collectively, these findings establish UFL1 as a critical regulator of skeletal muscle lipid homeostasis through the ACC1-FASN axis, independent of fatty acid oxidation, revealing a novel target for treating skeletal muscle lipid metabolic dysfunction.

BACKGROUND/OBJECTIVES:Sex-specific differences in the mechanisms of acute liver injury remain poorly understood. CDK5 regulatory subunit-associated protein 3 (CDK5RAP3) is crucial for liver development and endoplasmic reticulum (ER) homeostasis. This study aimed to investigate sex-dependent changes in CDK5RAP3 expression in a carbon tetrachloride (CCl4)-induced acute liver injury model and to explore the mechanisms underlying differential susceptibility between males and females. METHODS:Acute liver injury was induced in male and female mice by CCl4 administration. Liver injury was evaluated by serum biochemical parameters and histopathological analysis. CDK5RAP3 expression, inflammatory cytokines, and ER stress-related apoptotic markers were assessed. Hepatocyte apoptosis was examined by TUNEL staining. In addition, CDK5RAP3 was conditionally deleted in mouse embryonic fibroblasts (MEFs) using 4-hydroxytamoxifen to assess its direct role in regulating inflammatory and apoptotic responses in vitro. RESULTS:CCl4 exposure caused liver injury in both sexes, with male mice showing more severe biochemical and histological damage. CDK5RAP3 expression was significantly reduced after CCl4 treatment, particularly in males. Inflammatory mediators and ER stress-associated apoptotic markers were upregulated, accompanied by increased hepatocyte apoptosis. A similar enhancement of inflammatory and apoptotic signaling was observed in CDK5RAP3-deficient MEFs. CONCLUSIONS:Downregulation of CDK5RAP3 is associated with ER stress, inflammation, and apoptosis, contributing to increased susceptibility of male mice to acute liver injury. These findings provide insight into sex-specific mechanisms of hepatic injury and highlight CDK5RAP3 as a potential therapeutic target.

Ubiquitin-like modifier 1 ligating enzyme 1 (UFL1), the essential E3 ligase in the UFMylation system, plays a crucial yet undefined role in skeletal muscle development. In this study, our primary objective was to elucidate the function and molecular mechanism of UFL1 in myoblast survival and myofiber development. UFL1 deficiency in mice exacerbated ultra structural damage in myofibers and significantly increased myoblast apoptosis both in vivo and in vitro, as evidenced by upregulation of Cleaved Poly (ADP-ribose) polymerase (cleaved PARP), Cleaved Cysteinyl aspartate specific proteinase 3 (cleaved Caspase-3), and BCL2-associated X protein (BAX), alongside downregulation of B-cell lymphoma 2 (BCL2). Mechanistically, UFL1 knockout robustly activated the ER stress response, characterized by a significant increase in mRNA levels of Glucose-regulated protein 78 (GRP78), Activating transcription factor 4 (ATF4), and C/EBP homologous protein (CHOP), as well as specific activation of the Protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK)/Eukaryotic translation initiation factor 2 subunit alpha (eIF2α)/ATF4/CHOP signaling axis. Conversely, UFL1 overexpression effectively suppressed this pathway and reduced apoptosis. Notably, treatment with the PERK inhibitor GSK2606414 successfully reversed the UFL1 deficiency-induced upregulation of p-PERK, p-eIF2α, ATF4, and CHOP and rescued the apoptotic phenotype. Our study demonstrates for the first time that UFL1 is a critical regulator for maintaining myoblast survival and normal myofiber development, acting partly through suppressing the PERK-mediated ER sress. These findings provide novel insights into the pathogenesis of muscle developmental disorders and suggest UFL1 as a potential therapeutic target.

BACKGROUND:UFMylation plays an essential role in multiple physiological processes. Ribosomal protein L26 (RPL26), a principal target of UFMylation and a component of the ribosomal 60S subunit, is directly involved in protein synthesis. However, the biological significance of RPL26 UFMylation in intestinal epithelial cells (IECs) and intestinal homeostasis remains largely unknown. METHODS:IEC-specific RPL26K132/134R mutant (RPL26 UFMylation deficiency) mouse model (CKI) were constructed to investigate the role of RPL26 UFMylation in intestinal development and homeostasis. RESULTS:RPL26 UFMylation deficiency led to a loss of 70 kD and 25-35 kD UFMylated proteins, indicating reduced modification efficiency. Notably, CKI mice exhibited a significantly higher incidence of rectal prolapse and elevated inflammatory levels. More importantly, the small intestine and colon were markedly shortened, with a significant reduction in goblet and Paneth cells. Consistent with the loss of Paneth cells, lysozyme expression was profoundly decreased, accompanied by the downregulation of genes critical for Paneth cell differentiation, development, and lysozyme secretion. Further research found that RPL26 UFMylation deficiency suppressed endoplasmic reticulum aotophagy (ER-phagy) by promoting the ubiquitin-mediated degradation of autophagy related 16 like 1 (ATG16L1), consequently triggering ER stress-dependent apoptosis in Paneth cells. CONCLUSION:Our findings reveal a critical role for RPL26 UFMylation in maintaining IEC function and intestinal homeostasis, providing novel insights into the genetic mechanisms underlying intestinal health.

Understanding the regulatory mechanisms that determine skeletal muscle fiber-type composition is fundamental to elucidating muscle function and enhancing exercise metabolism. Although UFMylation plays a critical role in myofiber development, the expression pattern and specific function of its core E3 ligase, Ubiquitin-fold modifier-conjugating enzyme 1 (UFL1), in this process remain largely unknown. Herein, we found that UFL1 is highly expressed in fast-twitch fibers. Ultrastructural analysis in UFL1 deficiency revealed mitochondrial clustering and lipid metabolism disorders. Further metabolic assays showed that UFL1 deficiency induced a shift from glycolysis toward oxidative phosphorylation. In vitro and in vivo experiments confirmed that UFL1 deletion significantly promoted the transition from fast- to slow-twitch fibers. Meanwhile, UFL1 knockout also attenuated Rotenone-induced fast-twitch fiber transformation. Mechanistically, activation of the Ca²⁺/calcineurin (CaN)/Nuclear Factor of Activated T-Cells (NFAT) pathway significantly promoted the fast-to‐slow shift in fully differentiated myotubes, which was restored by FK506, VIVIT or UFL1 overexpression. In conclusion, UFL1 deficiency promoted the fast‐to‐slow myofiber type transition through Ca²⁺/CaN/NFAT signaling pathway. These findings provide novel insights into metabolic remodeling in skeletal muscle.

The liver is a central metabolic organ critical for maintaining systemic homeostasis. CDK5 regulatory subunit-associated protein 3 (CDK5RAP3), a substrate of E3 ubiquitin ligases, is involved in diverse signaling pathways and various disease processes; however, its specific role in liver pathology remains poorly understood. Here, we show that hepatocyte-specific deletion of CDK5RAP3 (CDK5RAP3Δ/Δhep) in mice leads to progressive liver disease by five months of age, characterized by hepatocyte apoptosis, cellular hypertrophy, fibrosis, and steatohepatitis. Liver macrophages in CDK5RAP3Δ/Δhep mice display a shift toward M2 polarization, and metabolomic analyses reveal disrupted hepatic glucose metabolism, including abnormal accumulation of UDP-glucose. Mechanistically, CDK5RAP3 deficiency leads to increased proteasomal degradation of HSP90AA1, which in turn reduces the enzymatic activity of UDP-glucose pyrophosphorylase (UGP2) and phosphoglucomutase 1 (PGM1). Together, these findings identify CDK5RAP3 as a key regulator of hepatic glucose metabolism and underscore its protective role against liver fibrosis and steatohepatitis.

Mitochondrial calcium homeostasis is essential for oxidative phosphorylation (OXPHOS) and cellular energy production. DDRGK1 is an ER‑localized adaptor protein, which is critical for maintaining ER homeostasis, protein stability, and organelle communication. However, the role of DDRGK1 in regulating mitochondrial function remains largely unknown. This study aims to define the role of DDRGK1 in mitochondrial calcium signaling and bioenergetics. Through biochemical analyses in cellular models, we identify DDRGK1 as a direct interactor and stabilizer of IP3R, preventing its ubiquitin-mediated degradation. DDRGK1 deficiency reduces IP3R protein levels, impairing mitochondrial calcium uptake and OXPHOS activity, as assessed by respirometry and ATP measurements. Consequent bioenergetic deficits are accompanied by calcium overload-induced ER stress, which activates C/EBP-homologous protein (CHOP) and suppresses the PGC‑1α pathway, thereby inhibiting mitochondrial biogenesis. The DDRGK1-IP3R axis constitutes a critical regulatory module in mitochondrial calcium signaling and energy metabolism. Disruption of this axis underlies bioenergetic failure and provides mechanistic insight into the pathogenesis of skeletal muscle metabolic disorders and related mitochondrial diseases.

Although UFMylation is implicated in skeletal muscle development, the role of its E3 ligase, ubiquitin-fold modifier 1 ligase 1 (UFL1), in bovine muscle and myofiber type determination is unclear. We profiled UFL1 expression in four muscles (biceps femoris (BF), longissimus dorsi (LD), trapezius (TR), psoas major (PM)) from 18-month-old Simmental and Angus bulls via histology, RT-qPCR, western blotting, and immunofluorescence. UFL1 mRNA and protein were significantly higher in fast-twitch muscles (LD, BF) than in slow-twitch PM. UFL1 localized to sarcolemma and sarcoplasmic reticulum, co-localized with MYHC-Fast in LD, and correlated positively with MYHC-Fast. Oxidative PM showed higher SDH/MDH activities, lower LDH activity, and greater lipid deposition than glycolytic LD. UFL1 correlated negatively with PLIN2. LD exhibited lower ACC1, FASN, PPARα, and CPT1A levels than PM. Collectively, UFL1 is specifically expressed in fast-twitch fibers, associates with lipid metabolic reprogramming, suggesting a role in muscle development and meat quality. This study identifies UFL1 as a novel candidate regulator of myofiber type determination in beef cattle.

Testosterone (T) produced by Leydig cells (LCs) is essential for male reproduction; yet, the regulatory mechanisms underlying steroidogenesis remain incompletely understood. Here, we investigated the role of cyclin-dependent kinase 5 regulatory subunit-associated protein 3 (CDK5RAP3) in Leydig cell development and steroidogenesis, based on its identification by immunoprecipitation-mass spectrometry (IP-MS) as a protein associated with steroidogenesis and cholesterol metabolism in mouse testicular tissue. Using human samples, we found that CDK5RAP3 expression was significantly reduced in Leydig cells from patients with spermatogenic failure (T < 10.4 nmol/L). Notably, CDK5RAP3 expression increased during mouse postnatal Leydig cell maturation and regeneration in an ethane dimethanesulfonate (EDS)-induced rat model. Functional analyses in primary LCs and MLTC-1 cells showed that hCG stimulation triggered CDK5RAP3 nuclear translocation without altering its overall expression, while CDK5RAP3 knockdown markedly impaired hCG-induced testosterone production and reduced the expression of the steroidogenic regulator steroidogenic acute regulatory (STAR) protein, as well as key steroidgenic enzymes, including cytochrome P450 family 11 subfamily A member 1 (CYP11A1), 17a-hydroxylase (CYP17A1), and 3β-hydroxysteroid dehydrogenase (HSD3B). Conversely, CDK5RAP3 overexpression enhanced testosterone production in the absence of hCG. In vivo, AAV2/9-mediated CDK5RAP3 silencing in adult mouse testes resulted in a significant reduction in serum testosterone levels compared with controls (3.60 ± 0.38 ng/mL vs. 1.83 ± 0.37 ng/mL). Mechanistically, CDK5RAP3 interacted with SMAD4 and CEBPB, and BMP pathway inhibition by Noggin rescued the testosterone deficit caused by CDK5RAP3 loss. Together, these findings identify CDK5RAP3 as an essential regulator of Leydig cell steroidogenesis and provide insight into its potential relevance to male infertility associated with low testosterone.

Ordered proliferation of skeletal muscle myoblasts is essential for muscle development and repair and requires coordinated metabolic remodeling. Acyl-CoA synthetase long-chain family member 3 (ACSL3) activates long-chain fatty acids and thereby supports lipid metabolic flux, but the post-translational mechanisms regulating ACSL3 in myoblasts remain incompletely defined. UFMylation is a ubiquitin-like post-translational modification mediated by a cascade that includes the E2-conjugating enzyme UFC1. Here, we investigated whether UFC1 regulates ACSL3 abundance and lipid metabolism in C2C12 myoblasts and primary mouse skeletal muscle myoblasts. UFC1 knockout or knockdown reduced ACSL3 protein abundance, decreased myoblast proliferation, and lowered cellular neutral and polar lipid signals. Transcriptomic gene set enrichment analysis further indicated suppression of pathways related to unsaturated fatty acid biosynthesis and fatty acid metabolism after UFC1 loss. Co-immunoprecipitation showed an association between UFC1 and ACSL3, and endogenous immunoprecipitation detected a UFC1-dependent UFM1 signal on ACSL3. Cycloheximide chase assays indicated accelerated ACSL3 degradation in UFC1-deficient cells, whereas the proteasome inhibitor MG132 partially restored ACSL3 protein abundance. Overexpression of ACSL3 alleviated lipid metabolic defects and partially rescued proliferation in UFC1-deficient myoblasts. These findings suggest that UFC1 contributes to ACSL3 protein abundance, probably through UFMylation-associated suppression of proteasomal degradation, thereby supporting lipid homeostasis and proliferation in skeletal muscle myoblasts.

Maintaining a healthy and dynamic mitochondrial network is essential for development and for cellular adaptation to physiological and stress conditions. UFMylation is an emerging post-translational modification, yet its involvement in mitochondrial quality control has remained largely unexplored. Here, we establish a previously unrecognized functional link between the UFMylation machinery and mitochondrial homeostasis by identifying the E1-like activating enzyme UBA5 as a key regulator of mitochondrial quality control. We show that UBA5 loss disrupts mitochondrial homeostasis, leading to persistent accumulation of damaged mitochondria and increased ROS accumulation, which in turn triggers p53 activation and DNA damage responses, enforces p21-associated G2/M arrest, and promotes early apoptosis. Mechanistically, although the PINK1–Parkin damage response is engaged, mitophagy execution is inefficient in UBA5-deficient cells, resulting in impaired clearance of dysfunctional mitochondria and exacerbated oxidative stress. Collectively, our findings uncover a previously unreported UFMylation–mitophagy axis and expand current understanding of how UBA5 governs mitochondrial homeostasis and cell fate decisions.

The acinus is the functional unit of the exocrine pancreas that produces and secretes a large quantity of digestive enzymes. Damage and dysfunction of pancreatic acinar cells (PACs) may lead to malnutrition, pancreatitis, and other pathological conditions. CDK5 regulatory subunit-associated protein 3 (Cdk5rap3), a multifunctional protein, is essential for animal development and normal physiology of multiple organs and tissues. Interestingly, the recent studies suggest its involvement in endoplasmic reticulum (ER)-phagy, a lysosomal degradation of the subdomains of the endoplasmic reticulum (ER). Herein, we attempted to investigate its physiological function in pancreatic acinar cells. We found that Cdk5rap3-deficient PACs contained fewer zymogen granules and underwent acinar-to-ductal metaplasia (ADM) and apoptosis, thereby resulting in a significant loss of acinar compartment. Interestingly, Cdk5rap3 ablation led to the increase of lysosomal hydrolase cathepsin B and lysosome-associated membrane protein 1 (LAMP1), indicating its novel function in the regulation of lysosomal homeostasis and activity. Elevated cathepsin B activity may lead to aberrant activation of trypsinogen and apoptosis of Cdk5rap3-deficient acinar cells, whereas the increase of lysosomal proteins may enhance lysosomal activity that in turn promotes ADM. Furthermore, Cdk5rap3 knockout led to substantial changes in the rough ER structure and a significant increase in selective ER membrane proteins, including cytoskeleton-linking membrane protein 63 (CLIMP63). Our results from both mouse tissues and tissue culture cells strongly suggest that Cdk5rap3 plays a pivotal role in regulating homeostasis of the lysosome and the ER that is essential for the survival and physiological function of pancreatic acinar cells.NEW & NOTEWORTHY Our current study has demonstrated a critical role of Cdk5rap3 protein in the maintenance and function of pancreatic acinar cells. Cdk5rap3 functions as a key regulator of the homeostasis of subcellular organelles, such as the lysosome and the ER, and its deficiency leads to loss of pancreatic mass and may contribute to the pathogenesis of pancreatic diseases.

Antibiotics are essential for treating bacterial infections, but the growing problem of antimicrobial resistance (AMR) undermines their effectiveness. Vaccines targeting multidrug-resistant (MDR) bacteria are urgently needed. Here, we developed next-generation mRNA vaccines encoding two novel target antigens: phosphate-specific transport protein (PstS) and DUF3748 domain-containing protein (YidR). The resulting fusion proteins exhibited high expression and secretion in vitro and provided strong protective efficacy in mice against Klebsiella pneumoniae (K. pneumoniae) and enterohemorrhagic Escherichia coli (EHEC), significantly reducing bacterial loads and organ damage. Moreover, the K. pneumoniae-based mRNA vaccine (KV3), encoding the PstS-YidR fusion protein, elicited notable cross-protection against four Enterobacteriaceae species, including K. pneumoniae, EHEC, Salmonella enterica (S. enterica), and Shigella flexneri (S. flexneri). In conclusion, this study demonstrates the potential of mRNA vaccines employing fusion protein containing a novel target antigen to combat MDR Enterobacteriaceae with significant cross-protective effects.

Ferroptosis, a recently discovered form of programmed cell death triggered by the excessive accumulation of iron-dependent lipid peroxidation products, plays a critical role in the development of various diseases. However, whether it is involved in the age-related decline in oocyte quality remains unexplored. Here, we took advantage of nano-proteomics to uncover that reduced ferritin heavy chain (Fth1) level is a major cause leading to the occurrence of ferroptosis in aged oocytes. Specifically, induction of ferroptosis in young oocytes by its activators RSL3 and FAC, or knockdown of Fth1 all phenocopied the meiotic defects observed in aged oocytes, including failed oocyte meiotic maturation, aberrant cytoskeleton dynamics, as well as impaired mitochondrial function. Transcriptome analysis showed that knockdown of Fth1 affected meiosis-related and aging-related pathways in oocytes. Conversely, inhibition of ferroptosis by its inhibitors or expression of Fth1 improved the quality of aged oocytes. We also validated the effects of ferroptosis on the porcine oocyte quality in vitro. Altogether, we demonstrate the contribution of ferroptosis to the age-induced oocyte defects and evidence that inhibition of ferroptosis might be a feasible strategy to ameliorate the reproductive outcomes of female animals at an advanced age.

Mitochondrial homeostasis, closely associated with mitophagy and antioxidant mechanisms, is essential for proper meiotic spindle assembly and chromosome segregation during oocyte maturation. SIRT5, known to modulate mitochondrial function under various conditions, has been shown to impact oocyte quality when inhibited, however, the precise mechanisms linking SIRT5 to mitochondrial homeostasis during meiotic progression remain unclear. In this study, we demonstrate that SIRT5 localizes predominantly at the periphery of the meiotic spindle and is enriched on chromosomes during oocyte maturation. Inhibition of SIRT5 led to significant meiotic defects, including disrupted spindle organization and chromosome misalignment. These defects were associated with increased histone acetylation, which impaired kinetochore-microtubule attachments. Moreover, SIRT5 inhibition resulted in mitochondrial dysfunction, subsequently elevating ROS levels and triggering oxidative stress, which further exacerbated meiotic abnormalities. Mechanistically, SIRT5 inhibition disrupted the balance of Parkin-dependent mitophagy by inducing ULK phosphorylation. Additionally, it activated the PI3K/Akt signaling pathway, which increased NADPH consumption and reduced GSH levels. Collectively, these findings reveal that SIRT5 plays dual roles in maintaining mitochondrial homeostasis during oocyte maturation: (1) by regulating Parkin-dependent mitophagy to prevent excessive mitochondrial clearance, and (2) by preserving the NADPH/GSH antioxidant system to ensure redox balance. These insights provide potential targets for improving oocyte quality and addressing mitochondrial dysfunction-related reproductive disorders in females.

Background/Objectives: CDK5RAP3 (CDK5 regulatory subunit-associated protein 3), is a ubiquitously expressed protein in mammalian tissues, with emerging evidence suggesting its critical role in liver hypoplasia. CDK5RAP3 knockout results in liver hypoplasia and liver injury in mice, and most liver injuries are associated with inflammation. However, the connection between its deficiency and liver inflammation remains unclear. The NLRP3 inflammasome is a ubiquitously expressed inflammatory pathway, and growing evidence links it to liver diseases. Therefore, we aim to investigate the relationship between CDK5RAP3 deficiency in the liver and the NLRP3 inflammasome. Methods: To clarify the pathological link between CDK5RAP3 deficiency and liver inflammation, we developed liver-specific CDK5RAP3 knockout mouse models and mouse embryonic fibroblasts (MEFs) from conditional knockout mice. Results: CDK5RAP3 deficiency induces hepatic injury and inflammation in mice, with increased expression of NLRP3 inflammasome components (NLRP3, ASC, Caspase-1) and GSDMD, all of which promote pyroptosis. Notably, CDK5RAP3-deficient MEFs exhibit compromised proliferative capacity and elevated apoptotic rates. Conclusions: Our findings demonstrate that CDK5RAP3 is indispensable for maintaining hepatic homeostasis. Its deficiency can induce liver damage and inflammatory cell death in mice. Therefore, CDK5RAP3 may be a candidate for further investigation in inflammatory liver disease models.

Background: Aberrant hepatic lipid metabolism is a key predisposing factor for dairy cow ketosis, with genetic factors playing a pivotal role in disease pathogenesis. However, systematic screening and functional validation of candidate genes for bovine ketosis remain limited. In this study, we aimed to identify genetic markers associated with clinical ketosis and explore their potential functional mechanisms underlying disease susceptibility. Methods: We conducted simplified genome sequencing (SuperGBS), genome-wide association studies (GWAS), and Sanger sequencing on Chinese Holstein cows, both healthy and with ketosis. Results: We reported that mitogen-activated protein kinase 1 (MAPK1) was significantly associated with clinical ketosis. Further investigation revealed concurrent upregulation of MAPK1 protein and disrupted hepatic lipid homeostasis in hepatocytes from in vivo and in vitro models. Critically, siRNA-mediated knockdown of MAPK1 reversed lipid metabolism processes and reduced lipid accumulation in β-Hydroxybutyric acid (BHB)-exposed bovine hepatocytes, thereby establishing MAPK1 activation as a driver of lipotoxicity in dairy cow ketosis. Additionally, we identified that supplementation of fibroblast growth factor 21 (FGF21) fusion protein not only reduced MAPK1 expression but also normalized hepatic lipid metabolism in BHB-exposed bovine hepatocytes. Conclusions: FGF21–MAPK1 imbalance is a reason for hepatic lipid metabolic dysfunction, providing a potential intervention approach to mitigate dairy cows’ ketosis.

Recent studies show obesity correlated with reduced sperm quality in males, but the mechanism is unclear. In this study, diet-induced obese (DIO) male mice exhibited disrupted luteinizing hormone (LH) pulse release due to altered function of the hypothalamic-pituitary-gonadal (HPG) axis. This alteration was caused by activation of nuclear factor kappa B (NF-κB) signaling in the hypothalamus, which led to decreased sperm quality. RNA sequencing (RNA-seq) analysis of the hypothalamic arcuate nucleus (ARC) revealed a signaling network involving protein phosphatase 2 catalytic subunit alpha (Ppp2ca). This network disrupted LH pulse secretion by inhibiting Akt kinase (AKT) and cAMP responsive element-binding protein 1 (CREB1) activities, thereby reducing KiSS-1 metastasis-suppressor (Kiss1) expression. Furthermore, overexpression of the Ppp2ca gene in the ARC led to disrupted LH patterns and reduced sperm quality. These findings offer new insights into the molecular mechanisms underlying sperm quality decline in DIO male mice.