O-GlcNAc is involved in modulating a wide range of cellular processes by influencing both the molecular properties of target proteins and the downstream cellular pathways they regulate (Figure 1) (21).

O-GlcNAcylation serves as a dynamic nutrient and stress sensor that regulates protein–protein interactions, transcriptional activity, and mitochondrial homeostasis. Through these mechanisms, O-GlcNAc modification orchestrates multiple PCD pathways-including apoptosis, autophagy, ferroptosis, pyroptosis, and necroptosis-to modulate cellular fate under pathological conditions. Dysregulated O-GlcNAc signaling contributes to the onset and progression of immune-inflammatory diseases, neurodegenerative disorders, cardiovascular diseases, cancers, organ and tissue injury, and metabolic disorders.

The term “apoptosis” was initially proposed in 1972 to describe an active, programmed form of cell death. Apoptotic cells exhibit characteristic features, including cell shrinkage, pyknosis, karyorrhexis, and apoptotic body generation (3). The extrinsic route, which is mediated by the TNF receptor superfamily, is activated through ligand binding to death receptors (46). The intrinsic pathway, regulated by the BCL-2 family, responds to cellular stress and operates through the mitochondrial pathway (47). As key executors, cysteine-dependent aspartate-directed proteases (caspases) drive apoptosis through selective activation. In humans, seven caspases regulate this process (48). Caspases-2, -8, -9, and -10 serve as initiators, whereas caspases-3, -6, and -7 function as effectors executing cell death (49). Among them, the executioner caspases, caspase-3 and caspase-7, are activated through precise cleavage at internal aspartate residues by the initiator caspase-9, following the formation of the apoptosome complex. This process is tightly regulated and necessitates the formation of a multicomponent apoptosome complex, orchestrated by Apaf-1 and cytochrome c, which is released from mitochondria under apoptotic conditions, in the presence of ATP (50, 51). Once activated, effector caspases execute a broad-spectrum proteolysis of key cellular substrates, driving irreversible commitment to apoptotic cell death (52). Essential for maintaining homeostasis, apoptosis regulates cell turnover, embryonic development, tissue differentiation, and regeneration. It is also implicated in pathological processes such as microenvironmental disruption, DNA damage, and tumor metastasis (53).

Many studies indicate a negative correlation between O-GlcNAcylation and apoptosis, although some studies suggest the opposite (Figure 2). For example, inhibition of O-GlcNAcylation promotes doxorubicin (Dox)-induced apoptosis in HCC cells (54). Reduced O-GlcNAcylation of NOS1AP leads to more severe neuronal apoptosis (55). O-GlcNAcylation of CD36 suppresses cardiomyocyte apoptosis (56). Inhibition of O-GlcNAcylation of RIPK1 at Ser331, Ser440, and Ser669 enhances the formation of the RIPK1/FADD/Caspase-8 complex, thereby promoting sunitinib-induced RIPK1-dependent apoptosis (23). Conversely, some studies suggest that O-GlcNAcylation is positively correlated with apoptosis. For example, O-GlcNAcylation of nNOS promotes neuronal apoptosis during glutamate stimulation by enhancing the formation of the nNOS–postsynaptic density protein 95 (PSD-95) complex. Inhibiting O-GlcNAcylation reduces hyperglycemia-induced podocyte apoptosis through the ER-stress-O-GlcNAcylation axis (57). Overall, the interplay between O-GlcNAcylation and apoptosis is context-dependent, varying with target proteins, cell types, and disease conditions. Specifically, whether O-GlcNAcylation promotes or inhibits apoptosis depends on its effect on the target protein and, in turn, the role of that protein in apoptosis within a particular cell type and environmental context. For example, overexpression of CD36 inherently suppresses cardiomyocyte apoptosis, and O-GlcNAcylation of CD36 enhances its stability and expression, thereby exerting an anti-apoptotic effect (56).

The interaction between autophagy and apoptosis is regulated by multiple signaling pathways and is highly dependent on the specific cellular or physiological context. Generally, autophagy functions as a cytoprotective process against apoptosis, whereas the activation of apoptosis-associated caspases suppresses autophagy. However, under specific conditions, autophagy or autophagy-related proteins may contribute to apoptosis or necrosis (58). Autophagy is the major process that mediates the transport of diverse intracellular components to lysosomes for degradation and recycling. When nutrients are scarce or cells are threatened by harmful factors such as bacteria, viruses, and oncogenes, autophagy is activated as a defense mechanism. This process begins with the release of mTOR inhibition, which allows the ULK complex and Class III PI3K complex to initiate phagophore formation. The ATG5-ATG12-ATG16 complex functions similarly to the ubiquitination machinery, promoting membrane elongation, whereas LC3 decorates the membrane to guide selective cargo sequestration. Autophagy involves cargo specificity through receptors such as p62 and NBR1, which mediate selective processes (59).

O-GlcNAc modification plays a pivotal role throughout the autophagic process, orchestrating autophagosome formation and autophagosome-lysosome fusion (Figure 2). This dynamic modification has been identified in numerous autophagy-related proteins, highlighting its importance in the fine-tuning of autophagic machinery (Figure 1) (60). For example, GRASP55 promotes autophagosome-lysosome fusion by facilitating the interaction between LC3-II and LAMP2, but its O-GlcNAcylation can inhibit this process and acts as a glucose sensor to modulate autophagosome maturation according to cellular metabolic status (61). Similarly, mutations at the O-GlcNAc sites of SNAP-29 enhance SNARE complex assembly, thereby promoting autophagosome–endosome/lysosome fusion and accelerating autophagic flux (62). Moreover, the autophagy-related kinases mTOR and AMPK exhibit a complex bidirectional crosstalk with O-GlcNAcylation, collectively contributing to the maintenance of cellular homeostasis (63). These findings suggest that O-GlcNAc not only regulates the fundamental processes of autophagy but may also dynamically modulate autophagic flux and cell fate by sensing nutritional and stress signals. Future studies could investigate how O-GlcNAc modifications differentially regulate autophagy under various pathological conditions and evaluate their potential as therapeutic targets.

Ferroptosis, a distinct form of regulated cell death, was first proposed in 2012 (64). It is typically accompanied by lipid peroxidation and excessive iron accumulation. The characteristics of ferroptosis include mitochondrial shrinkage, reduced mitochondrial cristae, and rupture of the outer mitochondrial membrane (65). In ferroptosis, phospholipid membranes abundant in polyunsaturated fatty acids (PUFAs) undergo excessive peroxidation. In particular, acyl-CoA synthetase long-chain family member 4 (ACSL4) facilitates the binding of PUFAs to coenzyme A (CoA), whereas lysophosphatidylcholine acyltransferase 3 (LPCAT3) reintegrates PUFA-CoA into phospholipids, making them part of the cell membrane. Ferrous iron (Fe²⁺) subsequently generates reactive oxygen species (ROS) via the Fenton reaction, triggering PUFA peroxidation, leading to membrane damage (66). Glutathione peroxidase 4 (GPX4) serves as a crucial intracellular regulatory factor, playing a significant role in maintaining redox homeostasis. Research indicates that decreased GPX4 activity and the accumulation of lipid peroxides disrupt membrane structure and cellular homeostasis, ultimately leading to ferroptosis (67).

O-GlcNAcylation plays a key role in regulating cellular iron homeostasis and ferroptosis by modulating ferritinophagy and iron uptake pathways (Figure 2) (68). For example, the removal of O-GlcNAc from the ferritin heavy chain (FTH) at S179 promotes its binding to the ferritinophagy receptor NCOA4, thereby facilitating ferritinophagy and ferroptosis (69). In Addition, reduced O-GlcNAc levels compromise the stability of FTH1, leading to disrupted iron homeostasis and increased iron accumulation. In contrast, elevated O-GlcNAc levels stabilize ferritin and limit the release of labile iron, thereby effectively preventing ferroptosis (70). Recent evidence suggests that reactive ROS can stimulate OGT enzymatic activity, thereby promoting the O-GlcNAcylation of FOXK2. This modification enhances the interaction between FOXK2 and importin α, facilitating its nuclear translocation and subsequent binding to the SLC7A11 promoter region. As a result, SLC7A11 transcription is elevated, ultimately suppressing HCC ferroptosis (71). In summary, O-GlcNAcylation finely regulates cellular iron homeostasis and ferroptosis through multiple mechanisms, playing a critical role in maintaining metabolic balance and influencing disease progression. A deeper understanding of its regulatory mechanisms in specific diseases may provide a foundation for developing precise ferroptosis-targeted interventions.

O-GlcNAcylation dynamically modulates apoptosis, autophagy, and ferroptosis. In apoptosis, O-GlcNAc modification of key proteins such as CDK5, RIPK1, and AKT regulates mitochondrial outer membrane permeabilization (MOMP), caspase activation, and the balance between cell survival and death. In autophagy, O-GlcNAcylation of GRASP55, SNAP29, SIRT3, and PINK1 influences autophagosome formation, lysosomal fusion, and mitochondrial quality control under cellular stress. Furthermore, O-GlcNAcylation modulates ferroptosis by targeting critical regulators including SLC7A11, FTH, TFRC, YAP, and ZEB1, thereby affecting lipid peroxidation, iron metabolism, and redox homeostasis. Through OGT- and OGA-mediated cycling, O-GlcNAcylation acts as a metabolic sensor that integrates nutrient and stress signals to coordinate apoptotic, autophagic, and ferroptotic responses. “G” indicates O-GlcNAc modification sites.

The phenomenon of pyroptosis was first observed in 1992 (72). Nearly a decade later, in 2001, this form of pro-inflammatory PCD was formally termed “pyroptosis,” to differentiate it from apoptosis, which is typically non-inflammatory (73). Pyroptosis is an inflammatory and lytic form of PCD, typically initiated by inflammasomes and executed by gasdermin proteins, a family of pore-forming proteins. The human gasdermin family consists of GSDMA, GSDMB, GSDMC, GSDMD, GSDME/DFNA5, and PVJK/DFNB59 (74). Gasdermin, the executioner of pyroptosis, is cleaved by activated caspases or granzymes to release its N-terminal domain (GSDMD-NT) (75), which subsequently forms pores in the cell membrane, leading to the release of IL-1β and IL-18, thereby amplifying inflammatory effects and activating immune responses (76, 77).

Pyroptosis can be categorized into two pathways: the caspase-1-dependent classical pathway and the caspase-1-independent non-classical pathway, the latter of which is mediated by human caspase-4/5 or mouse caspase-11 (78). Cell swelling, pore formation in the membrane, and the subsequent release of intracellular substances are the primary features of pyroptosis. Under normal physiological conditions, pyroptosis plays a crucial role in defending the host against microbial infections. For example, studies using macrophages induced to undergo pyroptosis without releasing IL-1β or IL-1α have shown that their supernatants upregulate gene signatures associated with cell migration, proliferation, and wound healing, thereby enhancing tissue repair in vivo (79). In addition, GSDMD deficiency in macrophages impairs tissue recovery and delays muscle regeneration (80). In summary, the pyroptotic secretome contains metabolites with tissue repair properties, which could be leveraged for therapeutic purposes. However, excessive pyroptosis can trigger uncontrolled and persistent inflammatory responses, which play a role in the progression of inflammatory diseases.

The role of O-GlcNAcylation in pyroptosis depends on target proteins (Figure 3). Some studies have shown that O-GlcNAcylation prevents pyroptosis, whereas others indicate that it promotes pyroptosis (Table 1). For example, O-GlcNAc modification of GSDMD at Ser338 has been shown to attenuate pyroptosis in HUVECs by disrupting its interaction with caspase-11 (81). Conversely, other studies have demonstrated that O-GlcNAcylation promotes pyroptosis and aggravates inflammation. High glucose (HG)-enhanced O-GlcNAcylation of GSDME at Ser339 site increased the levels of IL-1β, IL-18, TNF-α, NLRP3, GSDMD, and Caspase-1, thereby promoting pyroptosis in macrophages (82). Similarly, inhibiting the O-GlcNAcylation of NEK7 enhances its phosphorylation at Ser260 site, thereby blocking the interaction between NEK7 and NLRP3 and suppressing chondrocyte pyroptosis (83). These findings indicate that O-GlcNAcylation precisely modulates the interactions and phosphorylation status of target proteins at specific sites, thereby exerting bidirectional regulation of pyroptosis depending on the cellular context. Nevertheless, current research on the interplay between O-GlcNAcylation and pyroptosis remains limited, highlighting the urgent need to systematically elucidate its molecular mechanisms and functional roles in disease development and progression.

Necroptosis is a recently identified form of regulated necrosis that is driven primarily by RIPK3 and its substrate MLKL. This process critically depends on RIPK3-mediated phosphorylation of MLKL, which leads to MLKL oligomerization, translocation to the inner leaflet of the plasma membrane, and ultimately, cell lysis and death (84). Necroptosis can be triggered by a variety of upstream signals, including Toll-like receptors (85, 86), interferons, death receptors, and intracellular RNA and DNA sensors (87). Morphologically, necroptosis features disruption of the plasma membrane, swelling of intracellular organelles, and extrusion of cytoplasmic components (88). The decision between apoptosis and necroptosis is largely governed by the activity of caspase-8. When caspase-8 is inhibited, cells become susceptible to necroptosis. For instance, while the RIPK1–caspase-8 complex can mediate TNF-α-induced apoptosis, the use of caspase inhibitors diverts the cell death pathway toward necroptosis. In this context, RIPK3 is recruited to RIPK1 to form a necrosome that executes necroptosis (85). The delicate balance between Ripk1, Ripk3, and Mlkl is critical for maintaining epithelial homeostasis (89), supporting embryonic and perinatal development (90), and sustaining the survival of hematopoietic stem and progenitor cells (91).

Emerging studies suggest that O-GlcNAcylation modulates necroptosis by affecting the stability, phosphorylation, and interaction of RIPK1 and RIPK3 (Figure 3). Most studies indicate that elevated O-GlcNAcylation suppresses necroptosis, whereas reduced O-GlcNAcylation promotes its activation (Table 1). For example, in hepatocyte necroptosis, OGT suppresses necroptosis and fibrosis by downregulating RIPK3 and disrupting MLKL complex assembly (92). In addition, under LPS-induced inflammatory conditions, reduced O-GlcNAcylation of RIPK1 at serine 331 enhances erythrocyte necroptosis by impairing phosphorylation at serine 166 and promoting RIPK1-RIPK3 complex formation (93). Although current studies have demonstrated a negative regulatory role of O-GlcNAcylation in necroptosis, the existing evidence remains limited. The identified O-GlcNAc-modified proteins are confined primarily to core components of the necroptotic pathway. Given the dynamic and broad regulatory potential of O-GlcNAcylation, the identification of novel target proteins may reveal diverse regulatory mechanisms in necroptosis. A classification summary of O-GlcNAc-mediated regulation of PCD is provided in Table 1.

O-GlcNAc modification exerts multifaceted regulatory effects on PCD pathways. In the context of pyroptosis, O-GlcNAcylation of key signaling proteins such as NLRP3, GSDMD, GSDME, and NEK7 modulates inflammasome activation and the maturation of pro-inflammatory cytokines IL-1β and IL-18. Similarly, during necroptosis, O-GlcNAcylation of RIPK1, RIPK3, and TFF2 influences the assembly and phosphorylation of necrosome complexes in response to TNF-α, TRAIL, FASL, and TLR signaling. Through dynamic regulation by OGT and OGA, O-GlcNAcylation functions as a fine-tuning mechanism linking metabolic cues to inflammatory and cell death signaling, thereby maintaining immune homeostasis under physiological and pathological conditions. “G” indicates O-GlcNAc modification sites.

Increasing evidence suggests that O-GlcNAcylation centrally regulates immune-inflammatory diseases by modulating immune cell signaling, activation, and function. When O-GlcNAc cycling is blocked in macrophages, it promotes macrophage polarization toward the M1 phenotype, increasing iNOS expression and subsequently elevating the gene expression of pro-inflammatory cytokines (112). O-GlcNAcylation is essential for B-cell stability and antibody responses. OGT deficiency impairs B-cell receptor (BCR) signaling, while O-GlcNAcylation of Lyn at Ser19 is indispensable for BCR-mediated immune activation (113). Furthermore, in T-cells, glycoproteomic analysis revealed more than 200 O-GlcNAc-modified proteins, many of which are related to RNA metabolism. O-GlcNAc plays a key role in T-cell activation by regulating signaling pathways and protein function (114).

In immune-inflammatory diseases, O-GlcNAcylation exerts bidirectional regulation of inflammation by modulating the release of pro-inflammatory cytokines. For example, increasing O-GlcNAc levels in human synovial fibroblasts or on NF-κB p65 reduces cytokine release, attenuating inflammation and cardiovascular dysfunction in sepsis (115, 116). Similarly, GlcN and PUGNAc enhance NF-κB p65 O-GlcNAcylation at Ser536 to alleviate TNF-α-induced inflammatory stress (117). Conversely, under HG or TNF-α stimulation, O-GlcNAcylation of NF-κB or TAK1 can promote pro-inflammatory cytokine production and drive M1 macrophage polarization (118–121), highlighting its context-dependent effects. MAVS, a key antiviral signaling protein, is also regulated by OGT-mediated O-GlcNAcylation, which enhances innate immunity and suppresses viral replication (122). These cells infected with bacteria or viruses may undergo apoptosis or autophagy. If apoptotic cells are not efficiently cleared, they can progress to secondary necrosis, releasing intracellular components as DAMPs, which may trigger necroptosis or pyroptosis, activate the immune system, and induce inflammation (123). In the following section, we summarize the roles of O-GlcNAcylation in regulating autophagy, ferroptosis, pyroptosis, and necroptosis in immune-inflammatory diseases.

O-GlcNAc is highly expressed in the brain, where its dynamic regulation is essential for maintaining synaptic function and neuronal activity. Dysregulated O-GlcNAc metabolism has been increasingly linked to the pathogenesis of neurodegenerative disorders. In (AD), reduced O-GlcNAcylation promotes tau hyperphosphorylation and aggregation into neurofibrillary tangles, while OGA inhibition can restore tau O-GlcNAcylation, reduce abnormal phosphorylation and aggregation, improve cognitive function, and decrease amyloid-β levels (133, 134). Similarly, in Parkinson’s disease (PD), O-GlcNAc alleviates 6-OHDA-induced neuronal death, neuroinflammation, motor deficits, and mitochondrial dysfunction, partly by inhibiting α-synuclein aggregation at Ser87 (135–137). While these findings highlight the neuroprotective potential of O-GlcNAc, its precise mechanisms and long-term safety remain to be fully elucidated.

Building on these observations, recent studies have begun to explore how O-GlcNAc modulates multiple forms of PCD-including autophagy, pyroptosis, and necroptosis-in neurodegenerative diseases, providing new insights into its role in neuronal survival and pathology.

In the context of organ and tissue injury, elevated levels of O-GlcNAcylation regulate apoptosis, ferroptosis, and pyroptosis, thereby modulating repair and damage.

Cardiovascular diseases, including coronary artery disease, heart failure, hypertensive heart disease, and myocardial infarction, are prevalent and associated with high mortality, characterized by structural and functional cardiac impairments. Disruption of cardiomyocyte homeostasis and multiple forms of cell death contribute to cell loss, inflammation, and tissue remodeling, thereby exacerbating cardiac dysfunction. Elucidating the signaling pathways and regulatory networks governing these cell death processes is crucial for understanding cardiovascular diseases pathophysiology and developing novel therapeutic strategies (156). O-GlcNAcylation, serving as a bridge linking cellular metabolism and protein function, has emerged as a crucial regulator of cellular processes involved in maintaining cardiovascular homeostasis (157). Studies have shown that O-GlcNAcylation significantly influences the development and progression of cardiovascular diseases by modulating various forms of PCD.

O-GlcNAc plays a dual role in cancer, depending on the target protein, cell type, and microenvironment. Numerous studies have demonstrated that O-GlcNAcylation has emerged as a key regulator in multiple cancer types, including breast, endometrial, colorectal, lung, and pancreatic cancers (163). In breast cancer, O-GlcNAc modification of MITF at serine 49 promotes its interaction with importin α/β, thereby facilitating its translocation to the nucleus by suppressing senescence and promoting cell survival and proliferation (164). In endometrial cancer, O-GlcNAc modification promotes cell proliferation (165). In rectal cancer, O-GlcNAc modification of c-Myc at Ser415 enhances the stability of c-Myc and increases the expression of pyruvate dehydrogenase kinase 2 (PDK2), which reduces mitochondrial pyruvate metabolism, inhibits ROS production, and promotes the growth of xenograft tumors (166). In conclusion, this dynamic modification is intricately linked to tumor growth, invasion, drug resistance, metabolism, and immune evasion, and warrants further exploration. Multiple studies have shown that O-GlcNAc modification plays a critical role in cancer by regulating apoptosis, autophagy, and ferroptosis.

Metabolic diseases are a group of disorders caused by disturbances in energy or substance metabolism, mainly including diabetes, obesity, dyslipidemia, and metabolic syndrome, among which diabetes is the most representative and extensively studied type (177). Protein O-GlcNAcylation plays a pivotal role in maintaining normal cellular functions, and dysregulation of O-GlcNAcylation contributes to the pathogenesis of diseases, particularly metabolic disorders such as diabetes (178). Existing studies have shown that O-GlcNAcylation influences the onset and progression of metabolic disorders, particularly diabetes and its complications, by regulating apoptosis, autophagy, ferroptosis, and pyroptosis.