Overexpression of SESN1 improves mitochondrial damage and mitophagy, a potential therapeutic strategy for cognitive dysfunction after anaesthesia.

Postoperative cognitive dysfunction (POCD) is a prevalent central nervous system complication predominantly observed in elderly patients. Sevoflurane, a general anaesthetic agent, has been implicated in the development of POCD, yet the underlying regulatory mechanisms potentially involving Sestrin1 (SESN1), a stress-responsive protein that plays a critical role in cellular homeostasis and protection against stress-induced damage, including oxidative stress and DNA damage, remain elusive. This study endeavoured to elucidate the impact of SESN1 on sevoflurane-induced cognitive impairment in rats. Employing a model in which SESN1 was transfected into SD male rats and cognitive dysfunction was induced by sevoflurane. The Morris Water Maze test was used for behavioural evaluation, Enzyme-Linked Immunosorbent Assay, Western blotting and immunofluorescence were applied to assess the influence of SESN1 on the inflammatory response and mitophagy in the rat hippocampus. The study further aimed to uncover the putative mechanism by which SESN1, through SIRT1, might modulate cognitive function. Concurrently, levels of malondialdehyde, superoxide dismutase and mitochondrially produced ATP within the rat hippocampus were quantified. Experimental outcomes suggested that SESN1 overexpression significantly mitigated the deleterious effects of sevoflurane anaesthesia, ameliorated neuroinflammation and inflammasome activation, modified mitochondrial function and facilitated mitophagy. Additionally, SESN1, via the activation of SIRT1, may suppress inflammasome activation and mitochondrial dysfunction. Collectively, these findings underscore SESN1's integral role in counteracting sevoflurane-induced cognitive impairment, impeding inflammasome activation, enhancing mitochondrial function and fostering mitophagy, which appear to be intricately linked to SESN1-mediated SIRT1 activation. SESN1 is a novel therapeutic target for POCD, potentially advancing neuroprotective strategies in clinical settings.

SESN2 attenuates sevoflurane-induced cognitive impairment and neuroinflammation in rats.

Long-term use of sevoflurane, an inhalation anesthetic, could negatively impact cognitive function. Current studies have suggested that cognitive impairment induced by sevoflurane may be associated with neuroinflammation. Sestrin2 (SESN2), which belongs to a family of stress-inducible genes, has been reported to exert neuroprotective effects against brain injury. However, its role and underlying mechanisms in sevoflurane-induced cognitive dysfunction in aged rats remain unknown. A sevoflurane-induced aging rat injury model with or without SESN2 overexpression was constructed. The learning and memory abilities of rats were evaluated by the MWM test. ELISA assay and qRT-PCR were conducted to analyze the level of pro-inflammatory factors in the hippocampus. Levels of oxidative stress markers were measured by DHE staining or kit methods. Neuronal apoptosis in the hippocampus was detected using TUNEL assay. Expression of proteins were analyzed by western blot. Sevoflurane exposure caused elevated protein level of SESN2 in hippocampus and cognitive impairment of aged rats. Importantly, overexpression of SESN2 alleviated sevoflurane-induced cognitive dysfunction and inhibited the production of pro-inflammatory factors, oxidative stress, and neuronal apoptosis in the hippocampus. Furthermore, SESN2 overexpression suppressed NLRP3 inflammasome activation induced by sevoflurane. These findings suggested that SESN2 could exert neuroprotective against sevoflurane-induced nerve injury of aged rats through anti-oxidant and anti-inflammatory effects.

Molecular insights into Spindlin1-HBx interplay and its impact on HBV transcription from cccDNA minichromosome.

Molecular interplay between host epigenetic factors and viral proteins constitutes an intriguing mechanism for sustaining hepatitis B virus (HBV) life cycle and its chronic infection. HBV encodes a regulatory protein, HBx, which activates transcription and replication of HBV genome organized as covalently closed circular (ccc) DNA minichromosome. Here we illustrate how HBx accomplishes its task by hijacking Spindlin1, an epigenetic reader comprising three consecutive Tudor domains. Our biochemical and structural studies have revealed that the highly conserved N-terminal 2-21 segment of HBx (HBx2-21) associates intimately with Tudor 3 of Spindlin1, enhancing histone H3 "K4me3-K9me3" readout by Tudors 2 and 1. Functionally, Spindlin1-HBx engagement promotes gene expression from the chromatinized cccDNA, accompanied by an epigenetic switch from an H3K9me3-enriched repressive state to an H3K4me3-marked active state, as well as a conformational switch of HBx that may occur in coordination with other HBx-binding factors, such as DDB1. Despite a proposed transrepression activity of HBx2-21, our study reveals a key role of Spindlin1 in derepressing this conserved motif, thereby promoting HBV transcription from its chromatinized genome.

Prospects for Nerve Regeneration and Gene Therapy in the Treatment of Traumatic Brain Injury.

Traumatic brain injury (TBI) is a prevalent neurological disorder and a leading cause of death and disability worldwide. The high mortality rates result in a tremendous burden on society and families in terms of public health and economic costs. Despite advances in biomedical research, treatment options for TBI still remain limited, and there is no effective therapy to restore the structure and function of the injured brain. Regrettably, due to the excessive heterogeneity of TBI and the lack of objective and reliable efficacy evaluation indicators, no proven therapeutic drugs or drugs with clear benefits on functional outcomes have been successfully developed to date. Therefore, it is urgent to explore new therapeutic approaches to protect or regenerate the injured brain from different perspectives. In this review, we first provide a brief overview of the causes and current status of TBI and then summarize the preclinical and clinical research status of cutting-edge treatment methods, including nerve regeneration therapy and gene therapy, with the aim of providing valuable references for effective therapeutic strategies for TBI.

Evaluation of transjugular intrahepatic portosystemic shunt and modified sclerotherapy in preventing rebleeding of esophageal and gastric varices.

Esophageal and gastric varices are complications of decompensated portal hypertension due to cirrhosis, and gastrointestinal bleeding and can seriously trigger major bleeding and crisis life. Seriously endangers patients' physical and mental health and attracts great attention in the clinic. To compare the efficacy and safety of MES (combined with lauromacrogol and tissue adhesive) and TIPS in the treatment of esophageal and gastric varices. The 62 cases of esophageal and gastric variceal bleeding in our hospital were retrospectively analyzed. They were divided into the MES group and TIPS group according to the treatment method. The rebleeding rate, complications, 2-year birth rate, treatment cost, and hospitalization time within 2 years after operation were compared between the two groups. Among the 62 patients, there were 32 in the MES group and 30 in the TIPS group. The rebleeding rate within 1 year after operation in the MES group was higher than that in the TIPS group, but the difference was not statistically significant. The rebleeding rate within 2 years after operation in the MES group was 40.63%, significantly higher than 13.33% in the TIPS group (P < 0. 05). In the MES group, the incidence of hepatic encephalopathy after the operation was 9.38%, significantly lower than 33.33% in TIPS group (P < 0. 05). The survival rate within 2 years after operation in MES group (81.25%) and TIPS group (83.33), the difference was not statistically significant (P > 0.05). There was no significant difference in hospital stay between the MES group and TIPS group (P > 0.05). The treatment cost of the MES group was lower than that of the TIPS group (P < 0.05). MES is more suitable for development and promotion in grass-roots hospitals, but TIPS treatment should be carried out as soon as possible for patients with poor efficacy of endoscopic treatment.

Histone benzoylation serves as an epigenetic mark for DPF and YEATS family proteins.

Histone modifications and their functional readout serve as an important mechanism for gene regulation. Lysine benzoylation (Kbz) on histones is a recently identified acylation mark associated with active transcription. However, it remains to be explored whether putative readers exist to recognize this epigenetic mark. Here, our systematic binding studies demonstrated that the DPF and YEATS, but not the Bromodomain family members, are readers for histone Kbz. Co-crystal structural analyses revealed a 'hydrophobic encapsulation' and a 'tip-sensor' mechanism for Kbz readout by DPF and YEATS, respectively. Moreover, the DPF and YEATS family members display subtle yet unique features to create somewhat flexible engagements of different acylation marks. For instance, YEATS2 but not the other YEATS proteins exhibits best preference for Kbz than lysine acetylation and crotonylation due to its wider 'tip-sensor' pocket. The levels of histone benzoylation in cultured cells or in mice are upregulated upon sodium benzoate treatment, highlighting its dynamic regulation. In summary, our work identifies the first readers for histone Kbz and reveals the molecular basis underlying Kbz recognition, thus paving the way for further functional dissections of histone benzoylation.

Molecular basis for histone H3 "K4me3-K9me3/2" methylation pattern readout by Spindlin1.

Histone recognition by "reader" modules serves as a fundamental mechanism in epigenetic regulation. Previous studies have shown that Spindlin1 is a reader of histone H3K4me3 as well as "K4me3-R8me2a" and promotes transcription of rDNA or Wnt/TCF4 target genes. Here we show that Spindlin1 also acts as a potent reader of histone H3 "K4me3-K9me3/2" bivalent methylation pattern. Calorimetric titration revealed a binding affinity of 16 nm between Spindlin1 and H3 "K4me3-K9me3" peptide, which is one to three orders of magnitude stronger than most other histone readout events at peptide level. Structural studies revealed concurrent recognition of H3K4me3 and H3K9me3/2 by aromatic pockets 2 and 1 of Spindlin1, respectively. Epigenomic profiling studies showed that Spindlin1 colocalizes with both H3K4me3 and H3K9me3 peaks in a subset of genes enriched in biological processes of transcription and its regulation. Moreover, the distribution of Spindlin1 peaks is primarily associated with H3K4me3 but not H3K9me3, which suggests that Spindlin1 is a downstream effector of H3K4me3 generated in heterochromatic regions. Collectively, our work calls attention to an intriguing function of Spindlin1 as a potent H3 "K4me3-K9me3/2" bivalent mark reader, thereby balancing gene expression and silencing in H3K9me3/2-enriched regions.

Histone H3K27 methylation modulates the dynamics of FANCD2 on chromatin to facilitate NHEJ and genome stability.

Dysregulation of the homeostatic balance of histone H3 di- and tri-methyl lysine 27 (H3K27me2/3) levels caused by the mis-sense mutation of histone H3 (H3K27M) is reported to be associated with various types of cancers. In this study, we found that reduction in H3K27me2/3 caused by H3.1K27M, a mutation of H3 variants found in patients with diffuse intrinsic pontine glioma (DIPG), dramatically attenuated the presence of 53BP1 (also known as TP53BP1) foci and the capability of non-homologous end joining (NHEJ) in human dermal fibroblasts. H3.1K27M mutant cells showed increased rates of genomic insertions/deletions and copy number variations, as well as an increase in p53-dependent apoptosis. We further showed that both hypo-H3K27me2/3 and H3.1K27M interacted with FANCD2, a central player in the choice of DNA repair pathway. H3.1K27M triggered the accumulation of FANCD2 on chromatin, suggesting an interaction between H3.1K27M and FANCD2. Interestingly, knockdown of FANCD2 in H3.1K27M cells recovered the number of 53BP1-positive foci, NHEJ efficiency and apoptosis rate. Although these findings in HDF cells may differ from the endogenous regulation of the H3.1K27M mutant in the specific tumor context of DIPG, our results suggest a new model by which H3K27me2/3 facilitates NHEJ and the maintenance of genome stability.This article has an associated First Person interview with the first author of the paper.

Facilitating in vivo tumor localization by principal component analysis based on dynamic fluorescence molecular imaging.

Fluorescence molecular imaging has been used to target tumors in mice with xenograft tumors. However, tumor imaging is largely distorted by the aggregation of fluorescent probes in the liver. A principal component analysis (PCA)-based strategy was applied on the in vivo dynamic fluorescence imaging results of three mice with xenograft tumors to facilitate tumor imaging, with the help of a tumor-specific fluorescent probe. Tumor-relevant features were extracted from the original images by PCA and represented by the principal component (PC) maps. The second principal component (PC2) map represented the tumor-related features, and the first principal component (PC1) map retained the original pharmacokinetic profiles, especially of the liver. The distribution patterns of the PC2 map of the tumor-bearing mice were in good agreement with the actual tumor location. The tumor-to-liver ratio and contrast-to-noise ratio were significantly higher on the PC2 map than on the original images, thus distinguishing the tumor from its nearby fluorescence noise of liver. The results suggest that the PC2 map could serve as a bioimaging marker to facilitate in vivo tumor localization, and dynamic fluorescence molecular imaging with PCA could be a valuable tool for future studies of in vivo tumor metabolism and progression.

RCCD1 depletion attenuates TGF-ß-induced EMT and cell migration by stabilizing cytoskeletal microtubules in NSCLC cells.

Lung cancer is one of the most lethal cancers due to its highly metastatic spreading. The motility of lung cancer cells is regulated by paracrine factors, such as TGF-ß, in the tumor microenvironment through the induction of epithelial-to-mesenchymal transition (EMT). The stability of microtubules is reported to be associated with the EMT process and the migration of cancer cells. Here, we observed that RCC1 domain-containing protein 1 (RCCD1) is highly expressed in non-small cell lung cancer (NSCLC) patients with poor prognosis, and RCCD1 is much higher expressed in tumor tissues compared with adjacent normal tissues. Depletion of RCCD1 using siRNAs significantly inhibits the migration of lung cancer cells. Subsequent studies reveal that the loss of RCCD1 results in upregulation of acetylated α-tubulin levels and stabilizes cytoskeletal microtubules. Mechanistically, we observed that RCCD1 modulates the stability of microtubules through interacting with JMJD5. Furthermore, RCCD1 depletion significantly attenuates the TGF-ß-induced EMT process, as assessed by altered expression of epithelial and mesenchymal markers (Occludin, Vimentin and Snail), and inhibits TGF-ß-induced cell migration. Collectively, these findings support RCCD1 as a novel regulator of TGF-ß-induced EMT in NSCLC.

Pim-1 Kinase Regulating Dynamics Related Protein 1 Mediates Sevoflurane Postconditioning-induced Cardioprotection.

BACKGROUND: It is well documented that sevoflurane postconditioning (SP) has a significant myocardial protection effect. However, the mechanisms underlying SP are still unclear. In the present study, we investigated the hypothesis that the Pim-1 kinase played a key role in SP-induced cardioprotection by regulating dynamics-related protein 1 (Drp1). METHODS: A Langendorff model was used in this study. Seventy-two rats were randomly assigned into six groups as follows: CON group, ischemia reperfusion (I/R) group, SP group , SP+proto-oncogene serine/threonine-protein kinase 1 (Pim-1) inhibitor II group, SP+dimethylsufoxide group, and Pim-1 inhibitor II group (n = 12, each). Hemodynamic parameters and infarct size were measured to reflect the extent of myocardial I/R injury. The expressions of Pim-1, B-cell leukemia/lymphoma 2 (Bcl-2) and cytochrome C (Cyt C) in cytoplasm and mitochondria, the Drp1 in mitochondria, and the total Drp1 and p-Drp1ser637 were measured by Western blotting. In addition, transmission electron microscope was used to observe mitochondrial morphology. The experiment began in October 2014 and continued until July 2016. RESULTS: SP improved myocardial I/R injury-induced hemodynamic parametric changes, cardiac function, and preserved mitochondrial phenotype and decreased myocardial infarct size (24.49 ± 1.72% in Sev group compared with 41.98 ± 4.37% in I/R group; P< 0.05). However, Pim-1 inhibitor II significantly (P < 0.05) abolished the protective effect of SP. Western blotting analysis demonstrated that, compared with I/R group, the expression of Pim-1 and Bcl-2 in cytoplasm and mitochondria as well as the total p-Drp1ser637 in Sev group (P < 0.05) were upregulated. Meanwhile, SP inhibited Drp1 compartmentalization to the mitochondria followed by a reduction in the release of Cyt C. Pretreatment with Pim-1 inhibitor II significantly (P < 0.05) abolished SP-induced Pim-1/p-Drp1ser637 signaling activation. CONCLUSIONS: These findings suggested that SP could attenuate myocardial ischemia-reperfusion injury by increasing the expression of the Pim-1 kinase. Upregulation of Pim-1 might phosphorylate Drp1 and prevent extensive mitochondrial fission through Drp1 cytosolic sequestration.

Histone H2B monoubiquitination is a critical epigenetic switch for the regulation of autophagy.

Autophagy is an evolutionarily conserved cellular process that primarily participates in lysosome-mediated protein degradation. Although autophagy is a cytoplasmic event, how epigenetic pathways are involved in the regulation of autophagy remains incompletely understood. Here, we found that H2B monoubiquitination (H2Bub1) is down-regulated in cells under starvation conditions and that the decrease in H2Bub1 results in the activation of autophagy. We also identified that the deubiquitinase USP44 is responsible for the starvation-induced decrease in H2Bub1. Furthermore, the changes in H2Bub1 affect the transcription of genes involved in the regulation of autophagy. Therefore, this study reveals a novel epigenetic pathway for the regulation of autophagy through H2Bub1.

Depletion of JMJD5 sensitizes tumor cells to microtubule-destabilizing agents by altering microtubule stability.

Microtubules play essential roles in mitosis, cell migration, and intracellular trafficking. Drugs that target microtubules have demonstrated great clinical success in cancer treatment due to their capacity to impair microtubule dynamics in both mitotic and interphase stages. In a previous report, we demonstrated that JMJD5 associated with mitotic spindle and was required for proper mitosis. However, it remains elusive whether JMJD5 could regulate the stability of cytoskeletal microtubules and whether it affects the efficacy of microtubule-targeting agents. In this study, we find that JMJD5 localizes not only to the nucleus, a fraction of it also localizes to the cytoplasm. JMJD5 depletion decreases the acetylation and detyrosination of α-tubulin, both of which are markers of microtubule stability. In addition, microtubules in JMJD5-depleted cells are more sensitive to nocodazole-induced depolymerization, whereas JMJD5 overexpression increases α-tubulin detyrosination and enhances the resistance of microtubules to nocodazole. Mechanistic studies revealed that JMJD5 regulates MAP1B protein levels and that MAP1B overexpression rescued the microtubule destabilization induced by JMJD5 depletion. Furthermore, JMJD5 depletion significantly promoted apoptosis in cancer cells treated with the microtubule-targeting anti-cancer drugs vinblastine or colchicine. Together, these findings suggest that JMJD5 is required to regulate the stability of cytoskeletal microtubules and that JMJD5 depletion increases the susceptibility of cancer cells to microtubule-destabilizing agents.

JMJD5 (Jumonji Domain-containing 5) Associates with Spindle Microtubules and Is Required for Proper Mitosis.

Precise mitotic spindle assembly is a guarantee of proper chromosome segregation during mitosis. Chromosome instability caused by disturbed mitosis is one of the major features of various types of cancer. JMJD5 has been reported to be involved in epigenetic regulation of gene expression in the nucleus, but little is known about its function in mitotic process. Here we report the unexpected localization and function of JMJD5 in mitotic progression. JMJD5 partially accumulates on mitotic spindles during mitosis, and depletion of JMJD5 results in significant mitotic arrest, spindle assembly defects, and sustained activation of the spindle assembly checkpoint (SAC). Inactivating SAC can efficiently reverse the mitotic arrest caused by JMJD5 depletion. Moreover, JMJD5 is found to interact with tubulin proteins and associate with microtubules during mitosis. JMJD5-depleted cells show a significant reduction of α-tubulin acetylation level on mitotic spindles and fail to generate enough interkinetochore tension to satisfy the SAC. Further, JMJD5 depletion also increases the susceptibility of HeLa cells to the antimicrotubule agent. Taken together, these results suggest that JMJD5 plays an important role in regulating mitotic progression, probably by modulating the stability of spindle microtubules.

Heterochromatin remodeling by CDK12 contributes to learning in Drosophila.

Dynamic regulation of chromatin structure is required to modulate the transcription of genes in eukaryotes. However, the factors that contribute to the plasticity of heterochromatin structure are elusive. Here, we report that cyclin-dependent kinase 12 (CDK12), a transcription elongation-associated RNA polymerase II (RNAPII) kinase, antagonizes heterochromatin enrichment in Drosophila chromosomes. Notably, loss of CDK12 induces the ectopic accumulation of heterochromatin protein 1 (HP1) on euchromatic arms, with a prominent enrichment on the X chromosome. Furthermore, ChIP and sequencing analysis reveals that the heterochromatin enrichment on the X chromosome mainly occurs within long genes involved in neuronal functions. Consequently, heterochromatin enrichment reduces the transcription of neuronal genes in the adult brain and results in a defect in Drosophila courtship learning. Taken together, these results define a previously unidentified role of CDK12 in controlling the epigenetic transition between euchromatin and heterochromatin and suggest a chromatin regulatory mechanism in neuronal behaviors.

A conserved RAD6-MDM2 ubiquitin ligase machinery targets histone chaperone ASF1A in tumorigenesis.

Chromatin is a highly organized and dynamic structure in eukaryotic cells. The change of chromatin structure is essential in many cellular processes, such as gene transcription, DNA damage repair and others. Anti-silencing function 1 (ASF1) is a histone chaperone that participates in chromatin higher-order organization and is required for appropriate chromatin assembly. In this study, we identified the E2 ubiquitin-conjugating enzyme RAD6 as an evolutionary conserved interacting protein of ASF1 in D. melanogaster and H. sapiens that promotes the turnover of ASF1A by cooperating with a well-known E3 ligase, MDM2, via ubiquitin-proteasome pathway in H. sapiens. Further functional analyses indicated that the interplay between RAD6 and ASF1A associates with tumorigenesis. Together, these data suggest that the RAD6-MDM2 ubiquitin ligase machinery is critical for the degradation of chromatin-related proteins.

WITHDRAWN: WSTF Phosphorylation Specifically Links H3K9ac with H4K16ac through PCAF/WSTF/MOF Complex.

This article has been withdrawn by the authors.

RAD6 promotes homologous recombination repair by activating the autophagy-mediated degradation of heterochromatin protein HP1.

Efficient DNA double-strand break (DSB) repair is critical for the maintenance of genome stability. Unrepaired or misrepaired DSBs cause chromosomal rearrangements that can result in severe consequences, such as tumorigenesis. RAD6 is an E2 ubiquitin-conjugating enzyme that plays a pivotal role in repairing UV-induced DNA damage. Here, we present evidence that RAD6 is also required for DNA DSB repair via homologous recombination (HR) by specifically regulating the degradation of heterochromatin protein 1α (HP1α). Our study indicates that RAD6 physically interacts with HP1α and ubiquitinates HP1α at residue K154, thereby promoting HP1α degradation through the autophagy pathway and eventually leading to an open chromatin structure that facilitates efficient HR DSB repair. Furthermore, bioinformatics studies have indicated that the expression of RAD6 and HP1α exhibits an inverse relationship and correlates with the survival rate of patients.

MicroRNA-383 regulates the apoptosis of tumor cells through targeting Gadd45g.

BACKGROUND: MicroRNAs (miRNAs) are a class of small non-coding single-stranded RNA molecules that inhibit gene expression at post-transcriptional level. Gadd45g (growth arrest and DNA-damage-inducible 45 gamma) is a stress-response protein, which has been implicated in several biological processes, including DNA repair, the cell cycle and cell differentiation. RESULTS: In this work, we found that miR-383 is a negative regulator of Gadd45g. Forced expression of miR-383 decreased the expression of Gadd45g through binding to the 3' untranslated region (3'-UTR), whereas inhibition of miR-383 increased Gadd45g expression. The presence of miR-383 increased the cellular sensitivity to DNA damage in breast cancer cells, which was rescued by ectopic expression of Gadd45g without the 3'-UTR. miR-383 also regulates the expression of Gadd45g in embryonic stem (ES) cells, but not their apoptosis under genotoxic stress. miR-383 was further showed to negatively regulate ES cell differentiation via targeting Gadd45g, which subsequently modulates the pluripotency-associated genes. Taken together, our study demonstrates that miR-383 is a negative regulator of Gadd45g in both tumor cells and ES cells, however, has distinct function in regulating cell apoptosis. miR-383 may be used as antineoplastic agents in cancer chemotherapy. CONCLUSION: We demonstrate for the first time that miR-383 can specifically regulates the expression of Gadd45g by directly targeting to the 3-UTR region of Gadd45g mRNA, a regulatory process conserved in human tumor cells and mouse embryonic stem cells. These two compotents can be potentially used as antineoplastic agents in cancer chemotherapy.

KIF13B enhances the endocytosis of LRP1 by recruiting LRP1 to caveolae.

Multifunctional low-density lipoprotein (LDL) receptor-related protein 1 (LRP1) recognizes and internalizes a large number of diverse ligands, including LDL and factor VIII. However, little is known about the regulation of LRP1 endocytosis. Here, we show that a microtubule-based motor protein, KIF13B, in an unexpected and unconventional function, enhances caveolin-dependent endocytosis of LRP1. KIF13B was highly expressed in the liver and was localized on the sinusoidal plasma membrane of hepatocytes. KIF13B knockout (KO) mice showed elevated levels of serum cholesterol and factor VIII, and KO MEFs showed decreased uptake of LDL. Exogenous KIF13B, initially localized on the plasma membrane with caveolae, was translocated to the vesicles in the cytoplasm with LRP1 and caveolin-1. KIF13B bound to hDLG1 and utrophin, which, in turn, bound to LRP1 and caveolae, respectively. These linkages were required for the KIF13B-enhanced endocytosis of LRP1. Thus, we propose that KIF13B, working as a scaffold, recruits LRP1 to caveolae via LRP1-hDLG1-KIF13B-utrophin-caveolae linkage and enhances the endocytosis of LRP1.