Our recent study has also confirmed that CDK1-mediated pT345-EZH2 and pT487-EZH2 facilitate EZH2 ubiquitination and subsequent degradation in breast cancer [ xref ].

Moreover, a recent report has revealed that SYDM2 catalyzes EZH2-K307 di-methylation attenuating EZH2-ubiquitination degradation in breast cancer [ xref ].

OGT-mediated O -GlcNAcylation of EZH2 attenuates EZH2 ubiquitination in breast cancer cell [ xref , xref ]; PCAF-mediated EZH2-K348 acetylation inhibits CDK1 catalyzing pT345-EZH2 and pT487-EZH2 and increases EZH2 stability in lung cancer [ xref ].

SETD2-mediated mono-methylation of EZH2-K735 promotes EZH2 ubiquitination in prostate cancer [ xref ].

They confirmed that circ-ADD3 binding with EZH2 facilitates CDK1-mediated EZH2 phosphorylation on T345 and T487, which results in EZH2 ubiquitination degradation in HCC cells.

Sun et al. found that circ-ADD3, as a circular RNA, inhibits hepatocellular carcinoma (HCC) metastasis through facilitating EZH2 degradation through CDK1-mediated EZH2 ubiquitination [ xref ].

Subsequently, the researchers designed a highly specific NEK2 inhibitor, CMP3a, which can promote EZH2 ubiquitination degradation and inhibit GBM tumor growth.

Mechanically, they elucidated that YC-1 facilitates E3-ligase c-Cbl phosphorylation at T731 and T774, leading to the activation of c-Cbl and complex formation with EZH2, and then EZH2 ubiquitination degradation.

A series of small molecules have been shown to facilitate EZH2-ubiquitination degradation.

Moreover, researchers demonstrated that E3 ligase CHIP can mediate EZH2 ubiquitination degradation and subsequently derepress EZH2-silenced tumor suppressor genes by attenuating the H3K27me3 level in head and neck cancer cells [ xref ].

Ubiquitination, sumoylation, and deubiquitination of EZH2 in tumorigenesis and cancer metastasis.

A study showed that sumoylation of EZH2 is associated with EZH2 activity in U2OS cell (osteosarcoma cell line) [ xref ].

Moreover, another study demonstrated that JAK3-mediated EZH2 tyrosine (Y) Y244 phosphorylation, which suppresses PRC2 complex formation, resulting in EZH2 oncogenic function independent of its HMTase activity in natural killer/T-cell lymphoma (NKTL) [ xref ].

In addition, p38 catalyzing EZH2 phosphorylation at T367 residue elevates its localized to cytoplasm and promotes breast cancer cells distant metastasis [ xref ].

In addition, our recently studies discovered that PRMT1-mediated EZH2-R342 methylation attenuates CDK1-mediated EZH2-T345 and EZH2-T487 phosphorylation, which strengthens EZH2 stability [ xref , xref ].

They confirmed that circ-ADD3 binding with EZH2 facilitates CDK1-mediated EZH2 phosphorylation on T345 and T487, which results in EZH2 ubiquitination degradation in HCC cells.

Our recent research has illustrated that ANCR, a type of lncRNAs, promotes EZH2-T345 phosphorylation by associating with EZH2 [ xref ].

For instance, CDK1-mediated pT345-EZH2 and pT487-EZH2 facilitate EZH2 ubiquitination degradation in breast cancer cell, cervical cancer cell and lung cancer cell [ xref , xref , xref ]; JAK2 phosphorylates Y641-EZH2, leading to E3 ligase β-TrCP-mediated EZH2 degradation in lymphoma cell [ xref ]; and CDK5 phosphorylation of EZH2 at T261 residue results in the E3 ubiquitin ligase FBW7-mediated degradation of EZH2 in pancreatic cancer cell [ xref ].

Talha et al. [ xref ] revealed that p38 phosphorylated EZH2 at T367 site facilitating its cytoplasmic localization and interacting with vinculin and other cytoskeletal regulators of cell migration and invasion.

In 2018, Li et al. [ xref ] demonstrated that AMPK phosphorylates EZH2 at T311 residue to inhibit EZH2 binding with SUZ12, thereby attenuating the PRC2-dependent methylation of H3K27 and enhancing PRC2 target genes translation in ovarian and breast cancers.

SETD2-mediated mono-methylation of EZH2-K735 promotes EZH2 ubiquitination in prostate cancer [ xref ].

Furthermore, Kim et al. [ xref ] found that AKT-induced pS21-EZH2 elevates EZH2-mediated STAT3 methylation by increasing EZH2-STAT3 interaction in glioblastoma multiforme (GBM) stem-like cells.

In 2020, Yuan et al. [ xref ] reported that SETD2 methylates EZH2 at K735 promoting EZH2 degradation and impeding prostate cancer metastasis.

AKT-mediated pS21-EZH2 inhibits its methyltransferase activity by attenuating EZH2 associated with histone H3, which attenuates H3K27me3 level, increases EZH2 target genes expression, and facilitates breast cancer tumorigenesis.

Reports on AKT-mediated pS21-EZH2 support the presumption that pS21-EZH2 mediated by AKT results in EZH2 promoting oncogenesis by several novel functions, which is independent on PRC2-mediated target gene transcriptional silencing.

Interestingly, arsenic-induced pS21-EZH2 is mainly cytoplasmic localization.

Instead of transcriptional repression EZH2 target gene expression, pS21-EZH2 serves as a transcriptional co-activator in castration-resistant prostate cancer through PI3K/AKT signaling [ xref ].

AKT-mediated pS21-EZH2 inhibits its methyltransferase activity by attenuating EZH2 associated with histone H3, which attenuates H3K27me3 level, increases EZH2 target genes expression, and facilitates breast cancer tumorigenesis.

As early as 2005, Cha et al. [ xref ] showed phosphorylation of EZH2 at S21 (pS21-EZH2) by PI3K/AKT signaling in breast cancer cells.

For instance, AKT-mediated pS21-EZH2 can promote breast cancer tumorigenesis [ xref , xref ].

They confirmed that the OGT-EZH2 axis inhibits tumor suppression by repressing the expression of several key tumor suppression genes in breast carcinoma.

They demonstrated that ZRANB1 can bind, deubiquitinate, and stabilize EZH2, which enhances breast cancer tumorigenesis and metastasis.

We disclosed that ANCR-EZH2 interaction enhances CDK1 binding with EZH2 and increases the amount of pT345-EZH2, which results in EZH2 degradation and subsequently suppressing the oncogenesis and distant metastasis in breast cancer.

Although AKT-mediated-EZH2-S21 phosphorylation reduces its affinity toward histone H3, it does not change its subcellular localization or its interaction with Polycomb group protein SUZ12 and EED subunits.

A study revealed that Smurf2 can interact with EZH2 and mediate EZH2 ubiquitination-proteasome degradation.

We speculate that ANCR-EZH2 association may change the conformation of EZH2, which probably facilitates the recognition and binding of CDK1 on EZH2 to phosphorylate its T345 residue.

We disclosed that ANCR-EZH2 interaction enhances CDK1 binding with EZH2 and increases the amount of pT345-EZH2, which results in EZH2 degradation and subsequently suppressing the oncogenesis and distant metastasis in breast cancer.

Furthermore, Kim et al. [ xref ] found that AKT-induced pS21-EZH2 elevates EZH2-mediated STAT3 methylation by increasing EZH2-STAT3 interaction in glioblastoma multiforme (GBM) stem-like cells.

Recently, Wan et al. [ xref ] have elucidated that EZH2-K348 residue is acetylated by acetyltransferase P300/CBP-associated factor (PCAF) and is deacetylated by deacetylase SIRT1 in lung cancer cells.

H3K27me3 and EZH2 are involved in inhibiting and maintaining the low-level and stable state of fibrosis and inflammation genes in mesangial cells, while H3K27me3 and EZH2 are inhibited by TGF-β, which increases the expression of genes that mediate glomerular mesangial dysfunction and DN, leading to renal dysfunction ( xref ).

For the degradation of EZH2, JAK2 phosphorylates EZH2 at tyrosine 641 [ xref ].

Phosphorylation of EZH2 on serine 21 by protein kinase B (AKT) inhibits PRC2-mediated H3K27 enzymatic activity.

The interaction of EZH2 with ANGPTL4 [ xref ] was reported in human cytotrophoblasts.

For example, the transcription factor Yin Yang 1 (YY1) directly interacts with EZH2 and recruits it to specific genome sites to regulate gene expression.

Both EZH2 and YY1 are associated with repressing tumor suppressor APC in endometrioid endometrial carcinomas [ xref ].

Specifically, in acute myeloid leukemia (AML), both the RUNX1-RUNX1T1 fusion and the CBFB-MYH11 subtypes have lower levels of OGG1 expression, which correlate with increased therapeutic-induced cell cytotoxicity and good prognosis for improved, relapse-free survival compared with other AML patients.

Specifically, in acute myeloid leukemia (AML), both the RUNX1-RUNX1T1 fusion and the CBFB-MYH11 subtypes have lower levels of OGG1 expression, which correlate with increased therapeutic-induced cell cytotoxicity and good prognosis for improved, relapse-free survival compared with other AML patients.

Further, NF-kB inhibition by overexpression of IkB also results in S15 phosphorylation of mutant p53 via GADD45α mediated JNK1 activation ( xref ).

Chronic S15 phosphorylation of mutant p53 has been found in tumors where DNA damage signaling is constitutively activated ( xref , xref ).

It may form a complex with mutant p53 and MDM2 to block their ubiquitination mediated degradation or may form a complex with mutant p53 to prevent aggregation of mutant p53 by inhibiting MDM2 and CHIP in multiple cancer cell lines ( xref , xref ).

A recent study by Capaci et al. showed that mutant p53 can interact with HIF1α to induce miR-30d expression which promotes tubulo-vesiculation of Golgi apparatus leading to enhanced vesicular trafficking and secretion ( xref ) ( xref ).

Binding of mutant p53 to ETS2 can promote expression of Pla2g16 or nucleotide synthesis genes required for invasion depending upon the cancer type ( xref ) ( xref , xref ).

Furthermore, the binding of mutant p53 to EGR1 promotes MYO10 expression which drives breast cancer cell invasion ( xref ) ( xref ).

Further, mutant p53 can interact with PELP1 to promote resistance to platinum-based drugs in triple negative breast cancer ( xref ).

A further study reported that mutant p53 enhance the association of mutant p53 and PARP on the replicating DNA ( xref ) ( xref ).

GOF mutant p53 can bind to TopBP1 and attenuate ATR checkpoint response during replication stress ( xref ) ( xref ).

The compound, RETRA disrupts mutant p53-p73 complex restoring p73-dependent transcription and apoptosis ( xref ) ( xref ).

Short Interfering Mutant p53 Peptides (SIMP) can interact with different mutant p53 proteins and release p73, while peptides aptamers (PA) can inhibit mutant p53 transcription ( xref ) ( xref ).

Zhou et al. showed that mutant p53 binds to novel interacting partner AMPKα in glucose starvation conditions and inhibits its activation by other kinases leading to increased aerobic glycolysis, lipid production, and cell growth ( xref ) ( xref ).

This eliminates mitochondria-associated p53 which would otherwise be activated by PINK1 to mediate suppression of Nanog ( xref ) ( xref ).

Acetylation of p53 at K373 by CBP/p300 leads to dissociation of HDM2 and TRIM24 and subsequent activation of p53 which in turn transcriptionally activates p21, miR-34a, and miR-145 ( xref ).

A recent study by Alam et al. reveals GOF mutant p53 upregulates EFNB2 and activates ephrin B2 reverse signaling to impart enhanced chemoresistance to colorectal cancer cells ( xref ) ( xref ).

Acetylation of p53 at K373 by CBP/p300 leads to dissociation of HDM2 and TRIM24 and subsequent activation of p53 which in turn transcriptionally activates p21, miR-34a, and miR-145 ( xref ).

Notably, the effect of EZH2 inhibition-induced inactivation of mTOR complexes was not completely reversed after Deptor depletion, suggesting that Deptor might not be the only target of EZH2 epigenetic regulation.

After inhibiting Deptor expression with siRNA, the effect of EZH2 inhibition-induced inactivation of mTOR complexes was reversed.

EZH2 bound the Deptor promoter region and then regulated its transcriptional level (Fig.  xref d).

A ChIP assay demonstrated that EZH2 bound the promoter region of Deptor, an endogenous inhibitor of mTORC1 and mTORC2, and regulated the transcription of Deptor by modulating H3K27me3 in its promoter region.

The binding of EZH2 to the Deptor promoter was determined by ChIP assay.

Interestingly, another report indicated that CDK1 phosphorylates EZH2 at Thr 487, thereby leading to suppression of H3K27 trimethylation and consequent derepression of target gene expression xref .

A luciferase reporter assay and chromatin immunoprecipitation assay were performed to identify activation of CHK1 by EZH2.

Instructively, premature senescence in NP-MSCs could be largely alleviated using ASIC inhibitors, suggesting both ASIC1 and ASIC3 act decisively upstream to activate senescence programming pathways including p53-p21/p27 and p16-Rb1 signaling.

These events corresponded to the RB1-SIAH3 fusion and a novel RB1 rearrangement expected to correlate with the complete absence of RB1 protein expression.

RNA-sequencing revealed multiple fusions clustered within 13q14.1-q21.3, including a novel in-frame fusion of RB1-SIAH3 predicted to prematurely truncate the RB1 protein.

Interestingly, CRP-induced MMP9 expression and invasion on RA-FLSs were p38-dependent as addition of a p38 inhibitor (SB202190) but not a NF-κB inhibitor (PDTC) was capable of inhibiting CRP-induced MMP9 expression and cell invasion.

In contrast, blockade of CD16 produced no inhibitory effect on CRP-induced expression of CXCL8, CCL2, MMP9 and IL-6 by RA-FLSs ( xref ), suggesting that CRP may not signal through the CD16 to induce joint inflammation in vitro .

In contrast, blockade of CD16 produced no inhibitory effect on CRP-induced expression of CXCL8, CCL2, MMP9 and IL-6 by RA-FLSs ( xref ), suggesting that CRP may not signal through the CD16 to induce joint inflammation in vitro .

However, CRP- induced expression of CXCL8 was CD32-dependent as it was blunted by the antibody against CD32, whereas CRP-induced MMP9 was blocked by the antibody to CD64, demonstrating that differential signaling mechanisms for CRP in regulating CXCL8 and MMP9 expression in RA-FLSs.

In contrast, blockade of CD16 produced no inhibitory effect on CRP-induced expression of CXCL8, CCL2, MMP9 and IL-6 by RA-FLSs ( xref ), suggesting that CRP may not signal through the CD16 to induce joint inflammation in vitro .

As shown in xref , CRP-induced expression of CCL2 and IL-6 was blocked by either neutralizing antibody to CD32 or CD64 or both, suggesting that CRP signals through both CD32/CD64 to induce expression of CCL2 and IL-6.

In contrast, blockade of CD16 produced no inhibitory effect on CRP-induced expression of CXCL8, CCL2, MMP9 and IL-6 by RA-FLSs ( xref ), suggesting that CRP may not signal through the CD16 to induce joint inflammation in vitro .

As shown in xref , CRP-induced expression of CCL2 and IL-6 was blocked by either neutralizing antibody to CD32 or CD64 or both, suggesting that CRP signals through both CD32/CD64 to induce expression of CCL2 and IL-6.

It has been reported that CRP-induced cytokine expression is also regulated by TWIST transcriptionally in myeloma cells ( xref ).

We thus blocked CD32 or CD64 or both with neutralizing antibodies to differentially determine the signaling mechanisms of CRP-induced cytokine expression.

The data suggest that in hepatocytes merlin is functionally linked to the hippo pathway and acts upstream Mst1/2 by recruiting LATS to the membrane comparable to what has been shown in FH912 Schwann cell line.

Translocation of merlin to the nucleus allows merlin to bind and inhibit the E3 ubiquitin ligase CRL4 DCAF1 ( D DB1- and C ul4- A ssociated F actor 1) ( xref , xref ).

For example, in confluent human umbilical vein endothelial cells, merlin suppressed recruitment of Rac to the plasma membrane, and its silencing promoted recruitment of Rac1 to sites of extracellular matrix adhesion, and promoted cell growth ( xref ).

Previously, we showed that activation of ErbB2/ErbB3 receptors in primary rat Schwann cells by neuregulin-1 induced merlin phosphorylation at Ser518 via PKA ( xref ).

Merlin is phosphorylated at Ser10, Thr230 and Ser315 by Akt (also known as protein kinase B, PKB) and controls merlin’s proteasome-mediated degradation by ubiquitination to prevent its interaction with binding partners ( xref , xref ).

Merlin is phosphorylated at Ser10, Thr230 and Ser315 by Akt (also known as protein kinase B, PKB) and controls merlin’s proteasome-mediated degradation by ubiquitination to prevent its interaction with binding partners ( xref , xref ).

Merlin is phosphorylated at Ser10, Thr230 and Ser315 by Akt (also known as protein kinase B, PKB) and controls merlin’s proteasome-mediated degradation by ubiquitination to prevent its interaction with binding partners ( xref , xref ).

In sub-confluent primary Schwann cells, we found that merlin binds to paxillin and mediates merlin localization at the plasma membrane and association with β1-integrin and ErbB2, modifying the organization of the actin cytoskeleton in a cell density-dependent manner ( xref ).

Merlin-Amot interaction was required for merlin regulation of mitogenic MAPK signaling.

Moreover, in cultured Schwann cells, merlin interaction with Amot was demonstrated by co-immunoprecipitation of the endogenous proteins ( xref ).

Moreover, co-immunoprecipitation experiments revealed that merlin interacts with YAP1, although the interaction is not direct ( xref ).

Studies in human meningioma tumors and in paired cell lines—KY21MG1 or MENII-1 meningioma cell lines and AC1 arachnoidal cells—demonstrated that merlin loss was associated with increased YAP expression and nuclear localization.

Amot-p130 isoform bound to the WW domains of YAP and blocked LATS1 access to YAP.

The activation of Rac1 through CD44 was identified via the interaction of CD44 with Tiam-1, a Rac1 guanine nucleotide exchange factor (GEF) that catalyzes the replacement of the tightly-bound GDP with GTP.

Merlin inactivation of Src signaling was also shown in CNS glial cells, where merlin competitively inhibits Src binding to ErbB2 thereby preventing ErbB2-mediated Src phosphorylation and downstream mitogenic signaling.

Merlin interacts with tubulin and acetylated-tubulin and stabilizes the microtubules by attenuating tubulin turnover—lowering the rates of microtubule polymerization and depolymerization.

HDAC inhibitors disrupt the PP1-HDAC interaction facilitating Akt dephosphorylation and decrease human meningioma and schwannoma cell proliferation and schwannoma growth in an allograft model and meningioma growth in an intracranial xenograft model ( xref , xref , xref ).

Hyaluronan-CD44 interaction in astrocytes and an immortalized mouse mammary epithelial cell line, EpH4, leads to Rac1 signaling activation and actin cytoskeleton rearrangement ( xref , xref ).

Finally, a recent meningioma study of 73 patients found a high incidence of TERT promoter activating mutations in meningiomas undergoing malignant transformation in both NF2-related and sporadic meningiomas, whereas no TERT mutations were found in benign tumors.

The data suggest that in hepatocytes merlin is functionally linked to the hippo pathway and acts upstream Mst1/2 by recruiting LATS to the membrane comparable to what has been shown in FH912 Schwann cell line.

Translocation of merlin to the nucleus allows merlin to bind and inhibit the E3 ubiquitin ligase CRL4 DCAF1 ( D DB1- and C ul4- A ssociated F actor 1) ( xref , xref ).

For example, in confluent human umbilical vein endothelial cells, merlin suppressed recruitment of Rac to the plasma membrane, and its silencing promoted recruitment of Rac1 to sites of extracellular matrix adhesion, and promoted cell growth ( xref ).

Previously, we showed that activation of ErbB2/ErbB3 receptors in primary rat Schwann cells by neuregulin-1 induced merlin phosphorylation at Ser518 via PKA ( xref ).

Merlin is phosphorylated at Ser10, Thr230 and Ser315 by Akt (also known as protein kinase B, PKB) and controls merlin’s proteasome-mediated degradation by ubiquitination to prevent its interaction with binding partners ( xref , xref ).

Merlin is phosphorylated at Ser10, Thr230 and Ser315 by Akt (also known as protein kinase B, PKB) and controls merlin’s proteasome-mediated degradation by ubiquitination to prevent its interaction with binding partners ( xref , xref ).

Merlin is phosphorylated at Ser10, Thr230 and Ser315 by Akt (also known as protein kinase B, PKB) and controls merlin’s proteasome-mediated degradation by ubiquitination to prevent its interaction with binding partners ( xref , xref ).

In sub-confluent primary Schwann cells, we found that merlin binds to paxillin and mediates merlin localization at the plasma membrane and association with β1-integrin and ErbB2, modifying the organization of the actin cytoskeleton in a cell density-dependent manner ( xref ).

Merlin-Amot interaction was required for merlin regulation of mitogenic MAPK signaling.

Moreover, in cultured Schwann cells, merlin interaction with Amot was demonstrated by co-immunoprecipitation of the endogenous proteins ( xref ).

Moreover, co-immunoprecipitation experiments revealed that merlin interacts with YAP1, although the interaction is not direct ( xref ).

Studies in human meningioma tumors and in paired cell lines—KY21MG1 or MENII-1 meningioma cell lines and AC1 arachnoidal cells—demonstrated that merlin loss was associated with increased YAP expression and nuclear localization.

Amot-p130 isoform bound to the WW domains of YAP and blocked LATS1 access to YAP.

The activation of Rac1 through CD44 was identified via the interaction of CD44 with Tiam-1, a Rac1 guanine nucleotide exchange factor (GEF) that catalyzes the replacement of the tightly-bound GDP with GTP.

Merlin inactivation of Src signaling was also shown in CNS glial cells, where merlin competitively inhibits Src binding to ErbB2 thereby preventing ErbB2-mediated Src phosphorylation and downstream mitogenic signaling.

Merlin interacts with tubulin and acetylated-tubulin and stabilizes the microtubules by attenuating tubulin turnover—lowering the rates of microtubule polymerization and depolymerization.

HDAC inhibitors disrupt the PP1-HDAC interaction facilitating Akt dephosphorylation and decrease human meningioma and schwannoma cell proliferation and schwannoma growth in an allograft model and meningioma growth in an intracranial xenograft model ( xref , xref , xref ).

Hyaluronan-CD44 interaction in astrocytes and an immortalized mouse mammary epithelial cell line, EpH4, leads to Rac1 signaling activation and actin cytoskeleton rearrangement ( xref , xref ).

Finally, a recent meningioma study of 73 patients found a high incidence of TERT promoter activating mutations in meningiomas undergoing malignant transformation in both NF2-related and sporadic meningiomas, whereas no TERT mutations were found in benign tumors.

Several excellent studies have focused on the interactions between heparin/HS and the SARS-CoV-2 S protein, especially structure specificity of the carbohydrate chains.

Further elucidation of the heparin/HS–S protein interaction will facilitate the construction of structurally defined oligosaccharide sequences that can be prepared through several methods reported (Roy et al., xref ; Hansen et al., xref ; Baytas and Linhardt, xref ; Zhang et al., xref ).

To obtain insights into heparin/HS–S protein binding and virus infection in a safer circumstance, Tandon et al. pseudotyped SARS-CoV-2 S protein on a third-generation lentiviral (pLV) vector for testing the impact of various sulfated polysaccharides on transduction efficiency in mammalian cells (Tandon et al., xref ).

Interactions Between Heparin/HS and Cytokines.

Interactions Between Heparin/HS and the S Protein.

The polyproteins can be further cleaved into 15–16 non-structural proteins (nsp2-nsp16 or nsp1-nsp16).

Meanwhile, interactions of selectins and cytokines (e.g., IL-6 and TNF-α) with HS expressed on endothelial cells are crucial in controlling the recruitment of immune cells during inflammation.

In a recent study, interactions between heparin/HS and various cytokines were characterized by coupling surface plasmon resonance imaging for thermodynamic analysis method and Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF-MS) for structural determination (Przybylski et al., xref ).

The previously determined octasaccharide composed of IdoA2S-GlcNS6S repeating subunits could inhibit heparin–S protein interaction with an IC 50 of 38 nM.

Consistent with Liu et al. ( xref ), the authors claimed that the interaction between heparin and the S protein was independent of the anti-coagulant activity.

A ternary complex of heparin, ACE2, and the S protein was demonstrated by binding of S protein to immobilized heparin-BSA and titrating with biotinylated ACE2, in which case the binding of ACE2 increased in proportion to the amount of S protein bound to the heparin-BSA.

A ternary complex of heparin, ACE2, and the S protein was demonstrated by binding of S protein to immobilized heparin-BSA and titrating with biotinylated ACE2, in which case the binding of ACE2 increased in proportion to the amount of S protein bound to the heparin-BSA.

The analysis revealed a conformational selection mechanism of GAGs binding and determined the structural specificity in the FGF1–heparin complex.

This is an indication that RO-heparin could attenuate L- and P-selectin-mediated acute inflammation.

Gao et al. reported that periodate-oxidized, borohydride-reduced heparin (RO-heparin) could inhibit thioglycollate-induced peritoneal inflammation by preventing neutrophil recruitment dependent on the release of L- and P-selectin (Gao et al., xref ).

A ternary complex of heparin, ACE2, and the S protein was demonstrated by binding of S protein to immobilized heparin-BSA and titrating with biotinylated ACE2, in which case the binding of ACE2 increased in proportion to the amount of S protein bound to the heparin-BSA.

Captured carbohydrates were carried out directly on the biochip surface using MALDI-TOF-MS, while MS identification was enhanced by on-chip digestion of the cytokine-bound GAGs by heparinase treatment.

Further, NF-kB inhibition by overexpression of IkB also results in S15 phosphorylation of mutant p53 via GADD45α mediated JNK1 activation ( xref ).

Chronic S15 phosphorylation of mutant p53 has been found in tumors where DNA damage signaling is constitutively activated ( xref , xref ).

It may form a complex with mutant p53 and MDM2 to block their ubiquitination mediated degradation or may form a complex with mutant p53 to prevent aggregation of mutant p53 by inhibiting MDM2 and CHIP in multiple cancer cell lines ( xref , xref ).

A recent study by Capaci et al. showed that mutant p53 can interact with HIF1α to induce miR-30d expression which promotes tubulo-vesiculation of Golgi apparatus leading to enhanced vesicular trafficking and secretion ( xref ) ( xref ).

Binding of mutant p53 to ETS2 can promote expression of Pla2g16 or nucleotide synthesis genes required for invasion depending upon the cancer type ( xref ) ( xref , xref ).

Furthermore, the binding of mutant p53 to EGR1 promotes MYO10 expression which drives breast cancer cell invasion ( xref ) ( xref ).

Further, mutant p53 can interact with PELP1 to promote resistance to platinum-based drugs in triple negative breast cancer ( xref ).

A further study reported that mutant p53 enhance the association of mutant p53 and PARP on the replicating DNA ( xref ) ( xref ).

GOF mutant p53 can bind to TopBP1 and attenuate ATR checkpoint response during replication stress ( xref ) ( xref ).

The compound, RETRA disrupts mutant p53-p73 complex restoring p73-dependent transcription and apoptosis ( xref ) ( xref ).

Short Interfering Mutant p53 Peptides (SIMP) can interact with different mutant p53 proteins and release p73, while peptides aptamers (PA) can inhibit mutant p53 transcription ( xref ) ( xref ).

Zhou et al. showed that mutant p53 binds to novel interacting partner AMPKα in glucose starvation conditions and inhibits its activation by other kinases leading to increased aerobic glycolysis, lipid production, and cell growth ( xref ) ( xref ).

This eliminates mitochondria-associated p53 which would otherwise be activated by PINK1 to mediate suppression of Nanog ( xref ) ( xref ).

Acetylation of p53 at K373 by CBP/p300 leads to dissociation of HDM2 and TRIM24 and subsequent activation of p53 which in turn transcriptionally activates p21, miR-34a, and miR-145 ( xref ).

A recent study by Alam et al. reveals GOF mutant p53 upregulates EFNB2 and activates ephrin B2 reverse signaling to impart enhanced chemoresistance to colorectal cancer cells ( xref ) ( xref ).

Acetylation of p53 at K373 by CBP/p300 leads to dissociation of HDM2 and TRIM24 and subsequent activation of p53 which in turn transcriptionally activates p21, miR-34a, and miR-145 ( xref ).

Mechanically, they elucidated that YC-1 facilitates E3-ligase c-Cbl phosphorylation at T731 and T774, leading to the activation of c-Cbl and complex formation with EZH2, and then EZH2 ubiquitination degradation.

A series of small molecules have been shown to facilitate EZH2-ubiquitination degradation.

As we discussed, the PTM of the EZH2-ubiquitination pathway is an important negative regulator of EZH2.

For instance, CDK1-mediated pT345-EZH2 and pT487-EZH2 facilitate EZH2 ubiquitination degradation in breast cancer cell, cervical cancer cell and lung cancer cell [ xref , xref , xref ]; JAK2 phosphorylates Y641-EZH2, leading to E3 ligase β-TrCP-mediated EZH2 degradation in lymphoma cell [ xref ]; and CDK5 phosphorylation of EZH2 at T261 residue results in the E3 ubiquitin ligase FBW7-mediated degradation of EZH2 in pancreatic cancer cell [ xref ].

Mechanistically, YC-1 treatment promotes c-Cbl phosphorylation at T731 and T774, which results in c-Cbl-induced Src and ERK activation, leading to the formation of the c-Cbl-ERK-EZH2 complex and the consequent accumulation of EZH2 ubiquitination and proteasomal degradation.

The first research of EZH2 ubiquitination was from the Aaron lab’s work in 2011 [ xref ].

Ubiquitination, sumoylation, and deubiquitination of EZH2 in tumorigenesis and cancer metastasis.

We showed that R342-EZH2 methylation inhibits TRAF6-mediated EZH2 ubiquitination [ xref ].

Another recent study has reported that CDK5-mediated T261-EZH2 phosphorylation facilitates FBW7-mediated EZH2 ubiquitination and proteasome degradation in pancreatic cancer cells [ xref ].

Moreover, researchers demonstrated that E3 ligase CHIP can mediate EZH2 ubiquitination degradation and subsequently derepress EZH2-silenced tumor suppressor genes by attenuating the H3K27me3 level in head and neck cancer cells [ xref ].

They found that pT345-EZH2 and pT487-EZH2 facilitate EZH2 ubiquitination and hence its degradation by the proteasome pathway in human cervical cancer cells [ xref ].

Our recent study has also confirmed that CDK1-mediated pT345-EZH2 and pT487-EZH2 facilitate EZH2 ubiquitination and subsequent degradation in breast cancer [ xref ].

Moreover, a recent report has revealed that SYDM2 catalyzes EZH2-K307 di-methylation attenuating EZH2-ubiquitination degradation in breast cancer [ xref ].

OGT-mediated O -GlcNAcylation of EZH2 attenuates EZH2 ubiquitination in breast cancer cell [ xref , xref ]; PCAF-mediated EZH2-K348 acetylation inhibits CDK1 catalyzing pT345-EZH2 and pT487-EZH2 and increases EZH2 stability in lung cancer [ xref ].

SETD2-mediated mono-methylation of EZH2-K735 promotes EZH2 ubiquitination in prostate cancer [ xref ].

They confirmed that circ-ADD3 binding with EZH2 facilitates CDK1-mediated EZH2 phosphorylation on T345 and T487, which results in EZH2 ubiquitination degradation in HCC cells.

Sun et al. found that circ-ADD3, as a circular RNA, inhibits hepatocellular carcinoma (HCC) metastasis through facilitating EZH2 degradation through CDK1-mediated EZH2 ubiquitination [ xref ].

Subsequently, the researchers designed a highly specific NEK2 inhibitor, CMP3a, which can promote EZH2 ubiquitination degradation and inhibit GBM tumor growth.

Ubiquitination, sumoylation, and deubiquitination of EZH2 in tumorigenesis and cancer metastasis.

A study showed that sumoylation of EZH2 is associated with EZH2 activity in U2OS cell (osteosarcoma cell line) [ xref ].

Moreover, another study demonstrated that JAK3-mediated EZH2 tyrosine (Y) Y244 phosphorylation, which suppresses PRC2 complex formation, resulting in EZH2 oncogenic function independent of its HMTase activity in natural killer/T-cell lymphoma (NKTL) [ xref ].

In addition, p38 catalyzing EZH2 phosphorylation at T367 residue elevates its localized to cytoplasm and promotes breast cancer cells distant metastasis [ xref ].

In addition, our recently studies discovered that PRMT1-mediated EZH2-R342 methylation attenuates CDK1-mediated EZH2-T345 and EZH2-T487 phosphorylation, which strengthens EZH2 stability [ xref , xref ].

They confirmed that circ-ADD3 binding with EZH2 facilitates CDK1-mediated EZH2 phosphorylation on T345 and T487, which results in EZH2 ubiquitination degradation in HCC cells.

Our recent research has illustrated that ANCR, a type of lncRNAs, promotes EZH2-T345 phosphorylation by associating with EZH2 [ xref ].

For instance, CDK1-mediated pT345-EZH2 and pT487-EZH2 facilitate EZH2 ubiquitination degradation in breast cancer cell, cervical cancer cell and lung cancer cell [ xref , xref , xref ]; JAK2 phosphorylates Y641-EZH2, leading to E3 ligase β-TrCP-mediated EZH2 degradation in lymphoma cell [ xref ]; and CDK5 phosphorylation of EZH2 at T261 residue results in the E3 ubiquitin ligase FBW7-mediated degradation of EZH2 in pancreatic cancer cell [ xref ].

Talha et al. [ xref ] revealed that p38 phosphorylated EZH2 at T367 site facilitating its cytoplasmic localization and interacting with vinculin and other cytoskeletal regulators of cell migration and invasion.

In 2018, Li et al. [ xref ] demonstrated that AMPK phosphorylates EZH2 at T311 residue to inhibit EZH2 binding with SUZ12, thereby attenuating the PRC2-dependent methylation of H3K27 and enhancing PRC2 target genes translation in ovarian and breast cancers.

SETD2-mediated mono-methylation of EZH2-K735 promotes EZH2 ubiquitination in prostate cancer [ xref ].

Furthermore, Kim et al. [ xref ] found that AKT-induced pS21-EZH2 elevates EZH2-mediated STAT3 methylation by increasing EZH2-STAT3 interaction in glioblastoma multiforme (GBM) stem-like cells.

In 2020, Yuan et al. [ xref ] reported that SETD2 methylates EZH2 at K735 promoting EZH2 degradation and impeding prostate cancer metastasis.

AKT-mediated pS21-EZH2 inhibits its methyltransferase activity by attenuating EZH2 associated with histone H3, which attenuates H3K27me3 level, increases EZH2 target genes expression, and facilitates breast cancer tumorigenesis.

Reports on AKT-mediated pS21-EZH2 support the presumption that pS21-EZH2 mediated by AKT results in EZH2 promoting oncogenesis by several novel functions, which is independent on PRC2-mediated target gene transcriptional silencing.

Interestingly, arsenic-induced pS21-EZH2 is mainly cytoplasmic localization.

Instead of transcriptional repression EZH2 target gene expression, pS21-EZH2 serves as a transcriptional co-activator in castration-resistant prostate cancer through PI3K/AKT signaling [ xref ].

AKT-mediated pS21-EZH2 inhibits its methyltransferase activity by attenuating EZH2 associated with histone H3, which attenuates H3K27me3 level, increases EZH2 target genes expression, and facilitates breast cancer tumorigenesis.

As early as 2005, Cha et al. [ xref ] showed phosphorylation of EZH2 at S21 (pS21-EZH2) by PI3K/AKT signaling in breast cancer cells.

For instance, AKT-mediated pS21-EZH2 can promote breast cancer tumorigenesis [ xref , xref ].

They confirmed that the OGT-EZH2 axis inhibits tumor suppression by repressing the expression of several key tumor suppression genes in breast carcinoma.

They demonstrated that ZRANB1 can bind, deubiquitinate, and stabilize EZH2, which enhances breast cancer tumorigenesis and metastasis.

We disclosed that ANCR-EZH2 interaction enhances CDK1 binding with EZH2 and increases the amount of pT345-EZH2, which results in EZH2 degradation and subsequently suppressing the oncogenesis and distant metastasis in breast cancer.

Although AKT-mediated-EZH2-S21 phosphorylation reduces its affinity toward histone H3, it does not change its subcellular localization or its interaction with Polycomb group protein SUZ12 and EED subunits.

A study revealed that Smurf2 can interact with EZH2 and mediate EZH2 ubiquitination-proteasome degradation.

We speculate that ANCR-EZH2 association may change the conformation of EZH2, which probably facilitates the recognition and binding of CDK1 on EZH2 to phosphorylate its T345 residue.

We disclosed that ANCR-EZH2 interaction enhances CDK1 binding with EZH2 and increases the amount of pT345-EZH2, which results in EZH2 degradation and subsequently suppressing the oncogenesis and distant metastasis in breast cancer.

Furthermore, Kim et al. [ xref ] found that AKT-induced pS21-EZH2 elevates EZH2-mediated STAT3 methylation by increasing EZH2-STAT3 interaction in glioblastoma multiforme (GBM) stem-like cells.