USP11 deubiquitinates E-cadherin and maintains luminal fate of mammary tumor cells to suppress breast cancer.

Basal-like breast cancer may originate from luminal epithelial or cancerous cells. Inadequately repaired DNA damage impairs luminal differentiation and promotes aberrant luminal to basal trans-differentiation in mammary epithelial cells (MECs). Ubiquitin-specific peptidase 11 (USP11), a deubiquitinase, plays a critical role in DNA damage repair. The role of USP11 in controlling mammary cell differentiation and tumorigenesis remains poorly understood. We generated Usp11 knockout mice and breast cancer cell lines expressing wild-type (WT) and mutant form of USP11. By using these mutant mice, cell lines, and human USP11-deficient and -proficient breast cancer tissues, we tested how USP11 controls mammary cell fate. We generated Usp11 knock-out mice and found that deletion of Usp11 reduced the expression of E-cadherin and promoted DNA damage in MECs. Overexpression of WT USP11, but not a deubiquitinase-inactive mutant form of USP11, promoted luminal differentiation, enhanced DNA damage repair, and suppressed tumorigenesis in mice. Mechanistically, we found that USP11 enhanced the protein expression of E-cadherin dependent on its deubiquitinase activity, and that USP11 deubiquitinated E-cadherin at K738. We discovered that USP11 bound to E-cadherin through its C-terminal region. In human breast cancers, expression of USP11 was positively correlated with that of E-cadherin, and high USP11 predicted better recurrence-free survival. Our findings provide compelling genetic and biochemical evidence that USP11 not only promotes DNA damage repair but also deubiquitinates E-cadherin and maintains the luminal feature of mammary tumor cells, thereby suppressing luminal breast cancer.

BRCA1 promotes repair of DNA damage in cochlear hair cells and prevents hearing loss.

Cochlear hair cells (HCs) sense sound waves and allow us to hear. Loss of HCs will cause irreversible sensorineural hearing loss. It is well known that DNA damage repair plays a critical role in protecting cells in many organs. However, how HCs respond to DNA damage and how defective DNA damage repair contributes to hearing loss remain elusive.In this study, we showed that cisplatin induced DNA damage in outer hair cells (OHCs) and promoted OHC loss, leading to hearing loss in mice of either sex. Cisplatin induced the expression of Brca1, a DNA damage repair factor, in OHCs. Deficiency of Brca1 induced OHC and hearing loss, and further promoted cisplatin-induced DNA damage in OHCs, accelerating OHC loss. This study provides the first in vivo evidence demonstrating that cisplatin mainly induces DNA damage in OHCs and that BRCA1 promotes repair of DNA damage in OHCs and prevents hearing loss. Our findings not only demonstrate that DNA-damage inducible agent generates DNA damage in postmitotic HCs, but also suggest that DNA repair factors, like BRCA1, protect postmitotic HCs from DNA-damage induced cell death and hearing loss.Significance statement Sensorineural hearing loss is the most severe hearing loss caused by irreversible loss of cochlear hair cells. Hair cells are vulnerable to aging and ototoxic drug. Though DNA damage repair plays a critical role in protecting cells in many organs, it is poorly understood how DNA damage is repaired in hair cells. This study provides the first in vivo evidence demonstrating that cisplatin mainly induces DNA damage in outer hair cells and that BRCA1 promotes repair of DNA damage in outer hair cells and prevents outer hair cell loss as well as hearing loss.

Immune checkpoint reprogramming via sequential nucleic acid delivery strategy optimizes systemic immune responses for gastrointestinal cancer immunotherapy.

Monoclonal antibodies targeting immune checkpoints have been widely applied in gastrointestinal cancer immunotherapy. However, systemic administration of various monoclonal antibodies does not often result in sustained effects in reversing the immunosuppressive tumor microenvironment (TME), which may be due to the spatiotemporal dynamic changes of immune checkpoints. Herein, we reported a novel immune checkpoint reprogramming strategy for gastrointestinal cancer immunotherapy. It was achieved by the sequential delivery of siPD-L1 (siRNA for programmed cell death ligand 1) and pOX40L (plasmid for OX40 ligand), which were complexed with two cationic polymer brush-grafted carbon nanotubes (dense short (DS) and dense long (DL)) designed based on the structural characteristics of nucleic acids and brush architectures. Upon administrating DL/pOX40L for the first three dosages, then followed by DS/siPD-L1 for the next three dosages to the TME, it upregulated the stimulatory checkpoint OX40L on dendritic cells (DCs) and downregulated inhibitory checkpoint PD-L1 on tumor cells and DCs in a sequential reprogramming manner. Compared with other combination treatments, this sequential strategy drastically boosted the DCs maturation, and CD8+ cytotoxic T lymphocytes infiltration in tumor site. Furthermore, it could augment the local antitumor response and improve the T cell infiltration in tumor-draining lymph nodes to reverse the peripheral immunosuppression. Our study demonstrated that sequential nucleic acid delivery strategy via personalized nanoplatforms effectively reversed the immunosuppression status in both tumor microenvironment and peripheral immune landscape, which significantly enhanced the systemic antitumor immune responses and established an optimal immunotherapy strategy against gastrointestinal cancer.

Chromatin lysine acylation: On the path to chromatin homeostasis and genome integrity.

The fundamental role of cells in safeguarding the genome's integrity against DNA double-strand breaks (DSBs) is crucial for maintaining chromatin homeostasis and the overall genomic stability. Aberrant responses to DNA damage, known as DNA damage responses (DDRs), can result in genomic instability and contribute significantly to tumorigenesis. Unraveling the intricate mechanisms underlying DDRs following severe damage holds the key to identify therapeutic targets for cancer. Chromatin lysine acylation, encompassing diverse modifications such as acetylation, lactylation, crotonylation, succinylation, malonylation, glutarylation, propionylation, and butyrylation, has been extensively studied in the context of DDRs and chromatin homeostasis. Here, we delve into the modifying enzymes and the pivotal roles of lysine acylation and their crosstalk in maintaining chromatin homeostasis and genome integrity in response to DDRs. Moreover, we offer a comprehensive perspective and overview of the latest insights, driven primarily by chromatin acylation modification and associated regulators.

DOT1L-mediated RAP80 methylation promotes BRCA1 recruitment to elicit DNA repair.

Breast Cancer Type 1 Susceptibility Protein (BRCA1) is a tumor-suppressor protein that regulates various cellular pathways, including those that are essential for preserving genome stability. One essential mechanism involves a BRCA1-A complex that is recruited to double-strand breaks (DSBs) by RAP80 before initiating DNA damage repair (DDR). How RAP80 itself is recruited to DNA damage sites, however, is unclear. Here, we demonstrate an intrinsic correlation between a methyltransferase DOT1L-mediated RAP80 methylation and BRCA1-A complex chromatin recruitment that occurs during cancer cell radiotherapy resistance. Mechanistically, DOT1L is quickly recruited onto chromatin and methylates RAP80 at multiple lysines in response to DNA damage. Methylated RAP80 is then indispensable for binding to ubiquitinated H2A and subsequently triggering BRCA1-A complex recruitment onto DSBs. Importantly, DOT1L-catalyzed RAP80 methylation and recruitment of BRCA1 have clinical relevance, as inhibition of DOT1L or RAP80 methylation seems to enhance the radiosensitivity of cancer cells both in vivo and in vitro. These data reveal a crucial role for DOT1L in DDR through initiating recruitment of RAP80 and BRCA1 onto chromatin and underscore a therapeutic strategy based on targeting DOT1L to overcome tumor radiotherapy resistance.

Caspase-4 in glioma indicates deterioration and unfavorable prognosis by affecting tumor cell proliferation and immune cell recruitment.

Gliomas are the most common malignant tumors of the central nervous system, accounting for approximately 80% of all malignant brain tumors. Accumulating evidence suggest that pyroptosis plays an essential role in the progression of cancer. Unfortunately, the effect of the pyroptosis-related factor caspase-4 (CASP4) on immunotherapy and drug therapy for tumors has not been comprehensively investigated. In this study, we systematically screened six hub genes by pooling differential pyroptosis-related genes in The Cancer Genome Atlas (TCGA) glioma data and the degree of centrality of index-related genes in the protein-protein interaction network. We performed functional and pathway enrichment analyses of the six hub genes to explore their biological functions and potential molecular mechanisms. We then investigated the importance of CASP4 using Kaplan-Meier survival analysis of glioma patients. TCGA and the Chinese Glioma Genome Atlas (CGGA) databases showed that reduced CASP4 expression leads to the potent clinical deterioration of glioma patients. Computational analysis of the effect of CASP4 on the infiltration level and recruitment of glioma immune cells revealed that CASP4 expression was closely associated with a series of tumor-suppressive immune checkpoint molecules, chemokines, and chemokine receptors. We also found that aberrant CASP4 expression correlated with chemotherapeutic drug sensitivity. Finally, analysis at the cellular and tissue levels indicated an increase in CASP4 expression in glioma, and that CASP4 inhibition significantly inhibited the proliferation of glioma cells. Thus, CASP4 is implicated as a new prognostic biomarker for gliomas with the potential to further guide immunotherapy and chemotherapy strategies for glioma patients.

YZL-51N functions as a selective inhibitor of SIRT7 by NAD+ competition to impede DNA damage repair.

The NAD+-dependent deacetylase SIRT7 is a pivotal regulator of DNA damage response (DDR) and a promising drug target for developing cancer therapeutics. However, limited progress has been made in SIRT7 modulator discovery. Here, we applied peptide-based deacetylase platforms for SIRT7 enzymatic evaluation and successfully identified a potent SIRT7 inhibitor YZL-51N. We initially isolated bioactive YZL-51N from cockroach (Periplaneta americana) extracts and then developed the de novo synthesis of this compound. Further investigation revealed that YZL-51N impaired SIRT7 enzymatic activities through occupation of the NAD+ binding pocket. YZL-51N attenuated DNA damage repair induced by ionizing radiation (IR) in colorectal cancer cells and exhibited a synergistic anticancer effect when used in combination with etoposide. Overall, our study not only identified YZL-51N as a selective SIRT7 inhibitor from insect resources, but also confirmed its potential use in combined chemo-radiotherapy by interfering in the DNA damage repair process.

VCP/p97 UFMylation stabilizes BECN1 and facilitates the initiation of autophagy.

Macroautophagy/autophagy is essential for the degradation and recycling of cytoplasmic materials. The initiation of this process is determined by phosphatidylinositol-3-kinase (PtdIns3K) complex, which is regulated by factor BECN1 (beclin 1). UFMylation is a novel ubiquitin-like modification that has been demonstrated to modulate several cellular activities. However, the role of UFMylation in regulating autophagy has not been fully elucidated. Here, we found that VCP/p97 is UFMylated on K109 by the E3 UFL1 (UFM1 specific ligase 1) and this modification promotes BECN1 stabilization and assembly of the PtdIns3K complex, suggesting a role for VCP/p97 UFMylation in autophagy initiation. Mechanistically, VCP/p97 UFMylation stabilizes BECN1 through ATXN3 (ataxin 3)-mediated deubiquitination. As a key component of the PtdIns3K complex, stabilized BECN1 facilitates assembly of this complex. Re-expression of VCP/p97, but not the UFMylation-defective mutant, rescued the VCP/p97 depletion-induced increase in MAP1LC3B/LC3B protein expression. We also showed that several pathogenic VCP/p97 mutations identified in a variety of neurological disorders and cancers were associated with reduced UFMylation, thus implicating VCP/p97 UFMylation as a potential therapeutic target for these diseases. Abbreviation: ATG14:autophagy related 14; Baf A1:bafilomycin A1;CMT2Y: Charcot-Marie-Toothdisease, axonal, 2Y; CYB5R3: cytochromeb5 reductase 3; DDRGK1: DDRGK domain containing 1; DMEM:Dulbecco'smodified Eagle's medium;ER:endoplasmic reticulum; FBS:fetalbovine serum;FTDALS6:frontotemporaldementia and/or amyotrophic lateral sclerosis 6; IBMPFD1:inclusion bodymyopathy with early-onset Paget disease with or withoutfrontotemporal dementia 1; LC-MS/MS:liquid chromatography tandem mass spectrometry; MAP1LC3B/LC3B:microtubule associated protein 1 light chain 3 beta; MS: massspectrometry; NPLOC4: NPL4 homolog, ubiquitin recognition factor;PIK3C3: phosphatidylinositol 3-kinase catalytic subunit type 3;PIK3R4: phosphoinositide-3-kinase regulatory subunit 4; PtdIns3K:phosphatidylinositol 3-kinase; RPL26: ribosomal protein L26; RPN1:ribophorin I; SQSTM1/p62: sequestosome 1; UBA5: ubiquitin likemodifier activating enzyme 5; UFC1: ubiquitin-fold modifierconjugating enzyme 1; UFD1: ubiquitin recognition factor in ERassociated degradation 1; UFL1: UFM1 specific ligase 1; UFM1:ubiquitin fold modifier 1; UFSP2: UFM1 specific peptidase 2; UVRAG:UV radiation resistance associated; VCP/p97: valosin containingprotein; WT: wild-type.

The GATAD2B-NuRD complex drives DNA:RNA hybrid-dependent chromatin boundary formation upon DNA damage.

Double-strand breaks (DSBs) are the most lethal form of DNA damage. Transcriptional activity at DSBs, as well as transcriptional repression around DSBs, are both required for efficient DNA repair. The chromatin landscape defines and coordinates these two opposing events. However, how the open and condensed chromatin architecture is regulated remains unclear. Here, we show that the GATAD2B-NuRD complex associates with DSBs in a transcription- and DNA:RNA hybrid-dependent manner, to promote histone deacetylation and chromatin condensation. This activity establishes a spatio-temporal boundary between open and closed chromatin, which is necessary for the correct termination of DNA end resection. The lack of the GATAD2B-NuRD complex leads to chromatin hyperrelaxation and extended DNA end resection, resulting in homologous recombination (HR) repair failure. Our results suggest that the GATAD2B-NuRD complex is a key coordinator of the dynamic interplay between transcription and the chromatin landscape, underscoring its biological significance in the RNA-dependent DNA damage response.

GATA3 functions downstream of BRCA1 to promote DNA damage repair and suppress dedifferentiation in breast cancer.

BACKGROUND: Inadequate DNA damage repair promotes aberrant differentiation of mammary epithelial cells. Mammary luminal cell fate is mainly determined by a few transcription factors including GATA3. We previously reported that GATA3 functions downstream of BRCA1 to suppress aberrant differentiation in breast cancer. How GATA3 impacts DNA damage repair preventing aberrant cell differentiation in breast cancer remains elusive. We previously demonstrated that loss of p18, a cell cycle inhibitor, in mice induces luminal-type mammary tumors, whereas depletion of either Brca1 or Gata3 in p18 null mice leads to basal-like breast cancers (BLBCs) with activation of epithelial-mesenchymal transition (EMT). We took advantage of these mutant mice to examine the role of Gata3 as well as the interaction of Gata3 and Brca1 in DNA damage repair in mammary tumorigenesis. RESULTS: Depletion of Gata3, like that of Brca1, promoted DNA damage accumulation in breast cancer cells in vitro and in basal-like breast cancers in vivo. Reconstitution of Gata3 improved DNA damage repair in Brca1-deficient mammary tumorigenesis. Overexpression of GATA3 promoted homologous recombination (HR)-mediated DNA damage repair and restored HR efficiency of BRCA1-deficient cells. Depletion of Gata3 sensitized tumor cells to PARP inhibitor (PARPi), and reconstitution of Gata3 enhanced resistance of Brca1-deficient tumor cells to PARP inhibitor. CONCLUSIONS: These results demonstrate that Gata3 functions downstream of BRCA1 to promote DNA damage repair and suppress dedifferentiation in mammary tumorigenesis and progression. Our findings suggest that PARP inhibitors are effective for the treatment of GATA3-deficient BLBCs.

The ARID1A-METTL3-m6A axis ensures effective RNase H1-mediated resolution of R-loops and genome stability.

R-loops are three-stranded structures that can pose threats to genome stability. RNase H1 precisely recognizes R-loops to drive their resolution within the genome, but the underlying mechanism is unclear. Here, we report that ARID1A recognizes R-loops with high affinity in an ATM-dependent manner. ARID1A recruits METTL3 and METTL14 to the R-loop, leading to the m6A methylation of R-loop RNA. This m6A modification facilitates the recruitment of RNase H1 to the R-loop, driving its resolution and promoting DNA end resection at DSBs, thereby ensuring genome stability. Depletion of ARID1A, METTL3, or METTL14 leads to R-loop accumulation and reduced cell survival upon exposure to cytotoxic agents. Therefore, ARID1A, METTL3, and METTL14 function in a coordinated, temporal order at DSB sites to recruit RNase H1 and to ensure efficient R-loop resolution. Given the association of high ARID1A levels with resistance to genotoxic therapies in patients, these findings open avenues for exploring potential therapeutic strategies for cancers with ARID1A abnormalities.

The Lin28b/Wnt5a axis drives pancreas cancer through crosstalk between cancer associated fibroblasts and tumor epithelium.

Bidirectional signal transduction between tumor epithelial cells and tumor microenvironment (TME) is important for tumor development. Here we show that Lin28b/let-7 pathway is indispensable for modulating the expression of Wnt5a in tumor epithelium, which could be secreted and then up-regulates Lin28b in cancer-associated fibroblasts (CAFs). Moreover, we demonstrate that Lin28b in CAFs promoted growth of PDAC by inducing cytokine PCSK9's production. Using an orthotopic mouse model of PDAC, we find that depletion of Lin28b in CAFs reduced tumor weight, highlighting the importance of Lin28b in PDAC stroma. Thus, our study shows that the Lin28b-Wnt5a axis plays a critical role in bidirectional crosstalk between pancreatic tumor epithelium and TME and results in a pro-|tumorigenic contexture.

PARylated PDHE1α generates acetyl-CoA for local chromatin acetylation and DNA damage repair.

Chromatin relaxation is a prerequisite for the DNA repair machinery to access double-strand breaks (DSBs). Local histones around the DSBs then undergo prompt changes in acetylation status, but how the large demands of acetyl-CoA are met is unclear. Here, we report that pyruvate dehydrogenase 1α (PDHE1α) catalyzes pyruvate metabolism to rapidly provide acetyl-CoA in response to DNA damage. We show that PDHE1α is quickly recruited to chromatin in a polyADP-ribosylation-dependent manner, which drives acetyl-CoA generation to support local chromatin acetylation around DSBs. This process increases the formation of relaxed chromatin to facilitate repair-factor loading, genome stability and cancer cell resistance to DNA-damaging treatments in vitro and in vivo. Indeed, we demonstrate that blocking polyADP-ribosylation-based PDHE1α chromatin recruitment attenuates chromatin relaxation and DSB repair efficiency, resulting in genome instability and restored radiosensitivity. These findings support a mechanism in which chromatin-associated PDHE1α locally generates acetyl-CoA to remodel the chromatin environment adjacent to DSBs and promote their repair.

The HDAC6-RNF168 axis regulates H2A/H2A.X ubiquitination to enable double-strand break repair.

Histone deacetylase 6 (HDAC6) mediates DNA damage signaling by regulating the mismatch repair and nucleotide excision repair pathways. Whether HDAC6 also mediates DNA double-strand break (DSB) repair is unclear. Here, we report that HDAC6 negatively regulates DSB repair in an enzyme activity-independent manner. In unstressed cells, HDAC6 interacts with H2A/H2A.X to prevent its interaction with the E3 ligase RNF168. Upon sensing DSBs, RNF168 rapidly ubiquitinates HDAC6 at lysine 116, leading to HDAC6 proteasomal degradation and a restored interaction between RNF168 and H2A/H2A.X. H2A/H2A.X is ubiquitinated by RNF168, precipitating the recruitment of DSB repair factors (including 53BP1 and BRCA1) to chromatin and subsequent DNA repair. These findings reveal novel regulatory machinery based on an HDAC6-RNF168 axis that regulates the H2A/H2A.X ubiquitination status. Interfering with this axis might be leveraged to disrupt a key mechanism of cancer cell resistance to genotoxic damage and form a potential therapeutic strategy for cancer.

Keratin 17 Impacts Global Gene Expression and Controls G2/M Cell Cycle Transition in Ionizing Radiation-Induced Skin Damage.

Keratin 17 (K17) is a cytoskeletal protein that is part of the intermediate filaments in epidermal keratinocytes. In K17-/- mice, ionizing radiation induced more severe hair follicle damage, whereas the epidermal inflammatory response was attenuated compared with that in wild-type mice. Both p53 and K17 have a major impact on global gene expression because over 70% of the differentially expressed genes in the skin of wild-type mice showed no expression change in p53-/- or K17-/- skin after ionizing radiation. K17 does not interfere with the dynamics of p53 activation; rather, global p53 binding in the genome is altered in K17-/- mice. The absence of K17 leads to aberrant cell cycle progression and mitotic catastrophe in epidermal keratinocytes, which is due to nuclear retention, thus reducing the degradation of B-Myb, a key regulator of the G2/M cell cycle transition. These results expand our understanding of the role of K17 in regulating global gene expression and ionizing radiation-induced skin damage.

SMYD2 inhibition-mediated hypomethylation of Ku70 contributes to impaired nonhomologous end joining repair and antitumor immunity.

DNA damage repair (DDR) is a double-edged sword with different roles in cancer susceptibility and drug resistance. Recent studies suggest that DDR inhibitors affect immune surveillance. However, this phenomenon is poorly understood. We report that methyltransferase SMYD2 plays an essential role in nonhomologous end joining repair (NHEJ), driving tumor cells adaptive to radiotherapy. Mechanically, in response to DNA damage, SMYD2 is mobilized onto chromatin and methylates Ku70 at lysine-74, lysine-516, and lysine-539, leading to increased recruitment of Ku70/Ku80/DNA-PKcs complex. Knockdown of SMYD2 or its inhibitor AZ505 results in persistent DNA damage and improper repair, which sequentially leads to accumulation of cytosolic DNA, and activation of cGAS-STING pathway and triggers antitumor immunity via infiltration and activation of cytotoxic CD8+ T cells. Our study reveals an unidentified role of SMYD2 in regulating NHEJ pathway and innate immune responses, suggesting that SMYD2 is a promising therapeutic target for cancer treatment.

Loss of function of GATA3 regulates FRA1 and c-FOS to activate EMT and promote mammary tumorigenesis and metastasis.

Basal-like breast cancers (BLBCs) are among the most aggressive cancers, partly due to their enrichment of cancer stem cells (CSCs). Breast CSCs can be generated from luminal-type cancer cells via epithelial-mesenchymal transition (EMT). GATA3 maintains luminal cell fate, and its expression is lost or reduced in BLBCs. However, deletion of Gata3 in mice or cells results in early lethality or proliferative defects. It is unknown how loss-of-function of GATA3 regulates EMT and CSCs in breast cancer. We report here that haploid loss of Gata3 in mice lacking p18Ink4c, a cell cycle inhibitor, up-regulates Fra1, an AP-1 family protein that promotes mesenchymal traits, and downregulates c-Fos, another AP-1 family protein that maintains epithelial fate, leading to activation of EMT and promotion of mammary tumor initiation and metastasis. Depletion of Gata3 in luminal tumor cells similarly regulates Fra1 and c-Fos in activation of EMT. GATA3 binds to FOSL1 (encoding FRA1) and FOS (encoding c-FOS) loci to repress FOSL1 and activate FOS transcription. Deletion of Fra1 or reconstitution of Gata3, but not reconstitution of c-Fos, in Gata3 deficient tumor cells inhibits EMT, preventing tumorigenesis and/or metastasis. In human breast cancers, GATA3 expression is negatively correlated with FRA1 and positively correlated with c-FOS. Low GATA3 and FOS, but high FOSL1, are characteristics of BLBCs. Together, these data provide the first genetic evidence indicating that loss of function of GATA3 in mammary tumor cells activates FOSL1 to promote mesenchymal traits and CSC function, while concurrently repressing FOS to lose epithelial features. We demonstrate that FRA1 is required for the activation of EMT in GATA3 deficient tumorigenesis and metastasis.

Compensatory classification in spine sagittal malalignment with lumbar degeneration.

OBJECTIVE: To generate a compensatory classification to evaluate sagittal spinal malalignment with lumbar degeneration. METHODS: We included 162 patients with low back pain who underwent full-length spinal radiography in our hospital from August 2019 to October 2021. Using full-length spine X-rays, we measured pelvic tilt (PT), sacral slope (SS), pelvic incidence (PI), thoracic kyphosis (TK), lumbar lordosis (LL), C7 slope (C7S), thoracolumbar kyphosis (TLK), and C7 sagittal vertical axis (SVA). We also recorded the Oswestry Disability Index (ODI) and visual analog scale (VAS). Patients were divided into four groups based on the SRS-Schwab classification and four other groups based on the compensatory classification. RESULTS: ODI correlated with age, SS, LL, TK, C7-SVA, SRS-Schwab classification, and compensatory classification. Lumbar VAS score correlated with LL, TK, C7-SVA, SRS-Schwab classification, and compensatory classification. Leg VAS score only correlated with LL. Hidden imbalance and imbalance with compensation had more significant PT and larger TK than balance patients. The symptoms of the four compensatory classification groups gradually worsened. CONCLUSION: The spinal-pelvic sagittal balance in patients with lumbar degeneration based on pelvic and thoracic compensation can reflect spinal balance and symptoms. This parameter might help evaluate spine sagittal alignment in elderly patients with lumbar degeneration.

Protocol to purify the histone deacetylase SIRT6 and assess its activity in vitro.

The histone deacetylase known as sirtuin 6 (SIRT6) deacetylates both histone and non-histone proteins but has low deacetylase activity in vitro. Here, we present a protocol to monitor SIRT6-mediated deacetylation of long-chain acyl-CoA synthase 5 in the presence of palmitic acid. We describe the purification of His-SIRT6 and a Flag-tagged substrate. We then detail a deacetylation assay protocol that can be widely applied to study other SIRT6-mediated deacetylation events and the effect of SIRT6 mutations on its activity. For complete details on the use and execution of this protocol, please refer to Hou et al. (2022).1.

Cervical sagittal alignment changes following anterior cervical discectomy and fusion, laminectomy with fusion, and laminoplasty for multisegmental cervical spondylotic myelopathy.

OBJECTIVE: Cervical sagittal alignment changes (CSACs) influence outcomes and health-related quality-of-life. Anterior cervical discectomy and fusion (ACDF), laminectomy with fusion (LCF), and laminoplasty (LP) are common treatments for multisegmental cervical spondylotic myelopathy; however, these approaches need to be compared. METHODS: Our study included 167 patients who underwent ACDF, LCF, or LP. Patients were divided into four groups according to C2-C7 Cobb angle (CL): kyphosis (CL < 0°), straight (0° ≤ CL < 10°), lordosis (10° ≤ CL < 20°), and extreme lordosis (20° ≤ CL) groups. CSACs consist of two parts. CSAC from the preoperative period to the postoperative period is surgical correction change (SCC). CSAC from the postoperative period to the final follow-up period is postoperative lordosis preserving (PLP). Outcomes were evaluated using the Japanese Orthopaedic Association score and the neck disability index. RESULTS: ACDF, LCF, and LP had equivalent outcomes. ACDF had greater SCC than LCF and LP. During follow-up, lordosis decreased in the ACDF and LCF groups but increased in the LP group. For straight alignment, ACDF had greater CSAC and greater SCC than the LCF and LP groups but similar PLP. For lordosis alignment, ACDF and LP had positive PLP, and LCF had negative PLP. For extreme lordosis, ACDF, LP, and LCF had negative PLP; however, cervical lordosis in the LP group was relatively stable during follow-up. CONCLUSIONS: ACDF, LCF, and LP have different CSAC, SCC, and PLP according to a four-type cervical sagittal alignment classification. Preoperative cervical alignment is an important consideration in deciding the type of surgical treatment in CSM.