scholarly journals MO065TUBULAR EPITHELIAL CELL POLYPLOIDIZATION IS REQUIRED TO SURVIVE AKI BUT PROMOTES CKD DEVELOPMENT

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Letizia De Chiara ◽  
Elena Lazzeri ◽  
Maria Lucia Angelotti ◽  
Carolina Conte ◽  
Anna Julie Peired ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Cell Cycle ◽  
Renal Function ◽  
Acute Phase ◽  
Health Concern ◽  
In Vivo Models ◽  
Tubular Cells ◽  
Polyploid Cells

Abstract Background and Aims Acute kidney injury (AKI) is a global health concern. If not lethal in the acute phase, AKI is considered reversible based on the capacity of surviving tubular cells (TECs) to re-enter cell cycle. However, even mild AKI episodes carry a substantial risk of developing chronic kidney disease (CKD). The pathophysiological basis for this phenomenon remains unclear. Recently, we demonstrated that tubular epithelial cells (TECs) can undergo endoreplication-mediated hypertrophy after AKI. Endoreplications are incomplete cell cycles that lead to the formation of polyploid cells. As polyploid cells can provide increased cell function without restoring tissue integrity, we hypothesized that this mechanism is essential to survive AKI but it can be potentially maladaptive. Method To address this hypothesis, we employed a series of in vitro and in vivo transgenic models based on the Fluorescence Ubiquitin Cell Cycle Indicator (FUCCI) technology to monitor cell cycle phasing in combination with YAP1 overexpression or downregulation. In the in vivo models, YAP1 overexpressing mice and YAP1 knock-out mice were subjected to unilateral ischemia reperfusion injury (IRI) or glycerol-induced rhabdomyolysis to induce AKI. Polyploid cells have been then characterized by microarray analysis, cell sorting, super-resolution STED microscopy and transmission electron microscopy. Results In vitro, human renal tubular cells undergo polyploidization. The fraction of polyploid cells significantly decreases when YAP1 nuclear translocation is blocked, suggesting a possible involvement of YAP1 in regulating TEC polyploidization. After AKI in mice, the inhibition of YAP1 significantly reduces the number of polyploid cells and worsens kidney function resulting in a dramatic decrease of mouse survival. In contrast, YAP1 overexpression leads to an increase in the number of polyploid cells up to 20% of all TECs, further confirming the role of YAP1 in controlling TEC polyploidization. In YAP1 overexpressing mice, electron microscopy and STED analysis revealed the presence of both mononucleated and binucleated polyploid cells. Strikingly, these mice appear to be more prone to develop tubulointerstitial fibrosis acquiring a marked senescent phenotype along with significant decline in renal function thus suggesting an association between polyploidization and CKD development. Indeed, isolation of polyploid cells proved that these cells actively transcribe and secrete pro-fibrotic and senescent factors confirming their role in CKD progression. Conclusion These data suggest that: 1) polyploidization after AKI is required to preserve renal function in the acute phase of damage and it is essential for survival 2) polyploid cells are pro-fibrotic and senescent leading in the long run to the progression of AKI to CKD.

scholarly journals FC 041TUBULAR EPITHELIAL CELL POLYPLOIDY IS ESSENTIAL TO SURVIVE AKI BUT IT CONTRIBUTES TO CKD PROGRESSION

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
Letizia De Chiara ◽  
Elena Lazzeri ◽  
Paola Romagnani
Keyword(s):  
Cell Cycle ◽  
Renal Function ◽  
Epithelial Cells ◽  
Kidney Function ◽  
Nuclear Translocation ◽  
Ckd Progression ◽  
In Vivo Models ◽  
Polyploid Cells

Abstract Background and Aims Acute Kidney Injury (AKI) is a syndrome characterized by an acute deterioration of renal function. Due to its high prevalence and poor short-term outcomes, AKI represents a global healthcare issue. Many epidemiologic studies have indicated that the development of Chronic Kidney Disease (CKD) features prominently among the numerous long-term complications of AKI. The pathophysiological basis for this phenomenon has remained unclear so far. Recently, we found that tubular epithelial cells (TEC) undergo endoreplication-mediated hypertrophy after AKI. Endoreplications are incomplete cell cycles that lead to the formation of polyploid cells. Physiologically, polyploidy offers several advantages such as rapid adaptation to stress, compensation for cell loss and enhanced cell function. However, as renal epithelial cells are massively lost after AKI, TEC polyploidy may constitute an effective strategy to sustain a temporary functional recovery of the kidney without restoring tissue integrity potentially leading to CKD. Therefore, we hypothesized that: 1) polyploid TEC are an adaptive stress response required to maintain kidney function after AKI; 2) polyploid TEC are involved in the AKI to CKD progression. Method To address these hypotheses, we employed a series of in vitro and in vivo transgenic models based on the Fluorescence Ubiquitin Cell Cycle Indicator (FUCCI) technology to monitor cell cycle phasing in combination with YAP1 overexpression or downregulation. In the in vivo models, YAP1 overexpressing mice and YAP1 knock-out mice were subjected to unilateral ischemia reperfusion injury (IRI) or glycerol-induced rhabdomyolysis to induce AKI. Polyploid cells have been then characterized by single cell-RNA sequencing analysis, cell sorting, super-resolution STED microscopy and transmission electron microscopy in both mouse and human. Results In vitro, human renal tubular cells undergo polyploidization. The fraction of polyploid cells significantly decreases when YAP1 nuclear translocation is blocked, indicating a possible involvement of YAP1 in regulating TEC polyploidy. After AKI in mice, YAP1 expression and nuclear translocation are significantly enhanced. The inhibition of YAP1 following AKI, reduces the number of polyploid cells impairing kidney function and causing a dramatic reduction of mouse survival. In contrast, YAP1 overexpression leads to an increase in the number of polyploid cells even in the absence of kidney damage (healthy mice). Strikingly, these healthy mice, despite having an increased percentage of polyploid cells, present an unexpected decline of renal function suggesting an association between increased polyploidy and CKD development. Indeed, they develop tubulointerstitial fibrosis acquiring a marked senescent phenotype triggering CKD. Isolation of polyploid cells proved that these cells actively transcribe and secrete pro-fibrotic factors thus confirming their role in CKD progression. Conclusion Collectively, these data suggest that: 1) polyploidization after AKI is required to maintain kidney function allowing survival; 2) polyploid cells are pro-fibrotic leading in the long run to CKD progression.

scholarly journals p53 upregulated by HIF-1α promotes hypoxia-induced G2/M arrest and renal fibrosis in vitro and in vivo

2018 ◽  
Vol 11 (5) ◽  
pp. 371-382 ◽  
Author(s):  
Limin Liu ◽  
Peng Zhang ◽  
Ming Bai ◽  
Lijie He ◽  
Lei Zhang ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Transcriptional Activation ◽  
Renal Fibrosis ◽  
Intraperitoneal Administration ◽  
Luciferase Reporter ◽  
Loss Of Function ◽  
P53 Expression ◽  
Tubular Cells

Abstract Hypoxia plays an important role in the genesis and progression of renal fibrosis. The underlying mechanisms, however, have not been sufficiently elucidated. We examined the role of p53 in hypoxia-induced renal fibrosis in cell culture (human and rat renal tubular epithelial cells) and a mouse unilateral ureteral obstruction (UUO) model. Cell cycle of tubular cells was determined by flow cytometry, and the expression of profibrogenic factors was determined by RT-PCR, immunohistochemistry, and western blotting. Chromatin immunoprecipitation and luciferase reporter experiments were performed to explore the effect of HIF-1α on p53 expression. We showed that, in hypoxic tubular cells, p53 upregulation suppressed the expression of CDK1 and cyclins B1 and D1, leading to cell cycle (G2/M) arrest (or delay) and higher expression of TGF-β, CTGF, collagens, and fibronectin. p53 suppression by siRNA or by a specific p53 inhibitor (PIF-α) triggered opposite effects preventing the G2/M arrest and profibrotic changes. In vivo experiments in the UUO model revealed similar antifibrotic results following intraperitoneal administration of PIF-α (2.2 mg/kg). Using gain-of-function, loss-of-function, and luciferase assays, we further identified an HRE3 region on the p53 promoter as the HIF-1α-binding site. The HIF-1α–HRE3 binding resulted in a sharp transcriptional activation of p53. Collectively, we show the presence of a hypoxia-activated, p53-responsive profibrogenic pathway in the kidney. During hypoxia, p53 upregulation induced by HIF-1α suppresses cell cycle progression, leading to the accumulation of G2/M cells, and activates profibrotic TGF-β and CTGF-mediated signaling pathways, causing extracellular matrix production and renal fibrosis.

scholarly journals Mibefradil inhibits the proliferation of triple-negative breast cancer by targeting AURKA to regulate apoptosis signal pathway

2021 ◽  
Author(s):  
Xu Han ◽  
Xiujuan Qu ◽  
Beixing Liu ◽  
Yizhe Wang ◽  
Yang Cheng ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Cycle ◽  
Molecular Docking ◽  
Triple Negative Breast Cancer ◽  
Triple Negative ◽  
Therapeutic Drug ◽  
Specific Gene ◽  
In Vivo Models

Abstract Background: Triple negative breast cancer (TNBC) is a tumor characterized by high recurrence and mortality, but without effective targeted therapy. It is urgent to explore new treatment strategy to improve the efficacy of TNBC therapy. Methods: Transcriptomic profiling datasets of TNBC were used for screening TNBC specific gene sets. Drug prediction was performed in Connectivity map (CMap) database. Molecular docking method was used for analyzing drug targets. In vitro and in vivo models of TNBC were constructed to examine the drug efficacy. Results: We screened out Mibefradil, a T-type Ca2+ channel blocker, might be a potential therapeutic drug for TNBC by transcriptomics and bioinformatics analysis, and verified that Mibefradil could inhibit the proliferation of TNBC cells by inducing apoptosis and cell cycle arrest. Furthermore, by network pharmacology and molecular docking analysis, AURKA was predicted as the most possible drug target of Mibefradil. Finally, it was proved that Mibefradil treatment could induce apoptosis by decreasing protein expression and phosphorylation level of AURKA in vitro and in vivo. Conclusions: Mibefradil played anti-cancer role in TNBC cells by targeting to AURKA to induce cell cycle and apoptosis. Our results repurposed Mibefradil as a potential targeted drug of TNBC and provided a fundamental research for a novel strategy TNBC treatment.

scholarly journals Mitochondria-Targeted Antioxidant Mito-Tempo Protects Against Aldosterone-Induced Renal Injury In Vivo

2017 ◽  
Vol 44 (2) ◽  
pp. 741-750 ◽  
Author(s):  
Wei Ding ◽  
Tingyan Liu ◽  
Xiao Bi ◽  
Zhiling Zhang
Keyword(s):  
Electron Microscopy ◽  
Renal Function ◽  
Nlrp3 Inflammasome ◽  
Renal Injury ◽  
Periodic Acid ◽  
Inflammasome Activation ◽  
Periodic Acid Schiff ◽  
Nlrp3 Inflammasome Activation

Background/Aims: Growing evidence suggests mitochondrial dysfunction (MtD) and the Nlrp3 inflammasome play critical roles in chronic kidney disease (CKD) progression. We previously reported that Aldosterone (Aldo)-induced renal injury in vitro is directly caused by mitochondrial reactive oxygen species (mtROS)-mediated activation of the Nlrp3 inflammasome. Here we aimed to determine whether a mitochondria-targeted antioxidant (Mito-Tempo) could prevent Aldo-induced kidney damage in vivo. Methods: C57BL/6J mice were treated with Aldo and/or Mito-Tempo (or ethanol as a control) for 4 weeks. Renal injury was evaluated by Periodic Acid-Schiff reagent or Masson’s trichrome staining and electron microscopy. ROS were measured by DCFDA fluorescence and ELISA. MtD was determined by real-time PCR and electron microscopy. Activation of the Nlrp3 inflammasome and endoplasmic reticulum stress (ERS) was detected via western blot. Results: Compared with control mice, Aldo-infused mice showed impaired renal function, increased mtROS production and MtD, Nlrp3 inflammasome activation, and elevated ERS. We showed administration of Mito-Tempo significantly improved renal function and MtD, and reduced Nlrp3 inflammasome activation and ERS in vivo. Conclusion: Mitochondria-targeted antioxidants may attenuate Aldo-infused renal injury by inhibiting MtD, the Nlrp3 inflammasome, and ERS in vivo. Therefore, targeting mtROS might be an effective strategy for preventing CKD.

scholarly journals Cell cycle inhibition therapy that targets stathmin in in vitro and in vivo models of breast cancer

2013 ◽  
Vol 20 (5) ◽  
pp. 298-307 ◽  
Author(s):  
C Miceli ◽  
A Tejada ◽  
A Castaneda ◽  
S J Mistry
Keyword(s):  
Breast Cancer ◽  
Cell Cycle ◽  
In Vivo Models ◽  
Cell Cycle Inhibition

scholarly journals The p21 dependent G2 arrest of the cell cycle in epithelial tubular cells links to the early stage of renal fibrosis

2019 ◽  
Author(s):  
Takayuki Koyano ◽  
Masumi Namba ◽  
Tomoe Kobayashi ◽  
Kyomi Nakakuni ◽  
Daisuke Nakano ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Renal Fibrosis ◽  
Kinase Inhibitor ◽  
Early Stage ◽  
G2 Arrest ◽  
Tubular Cells ◽  
Initial Stage ◽  
Deficient Mice

AbstractRenal fibrosis is accompanied with the progression of chronic kidney disease (CKD). Despite a number of past and ongoing studies, our understanding of the underlying mechanisms remains elusive. Here we explored the progression of renal fibrosis by using a mouse model, unilateral ureter obstruction (UUO). We found that in the initial stage of the progression where extracellular matrix did not deposit yet, the proximal tubular cells arrested at the G2 of the cell cycle. This G2 arrest was induced prior to activation of both DNA damage checkpoint and Wnt/β-Catenin pathway. Further analyses in vivo and in vitro indicated the cyclin dependent kinase inhibitor p21 is involved in the G2 arrest after the damage. The newly produced monoclonal antibody against p21 revealed that the p21 levels were sharply upregulated in response to the damage during the initial stage, but dropped down toward the later stage. To examine the function of p21 in the progression of renal fibrosis, we constructed the novel p21 deficient mice by i-GONAD. Compared with wild-type mice, p21 deficient mice showed the exacerbation of the fibrosis. Thus we propose that during the initial stage of the fibrosis following the renal damage, tubular cells arrest in the G2 phase depending on p21, thereby safeguarding the kidney functions.

scholarly journals Nonalcoholic Fatty Liver Disease and Non-Alcoholic Steatohepatitis: Current Issues and Future Perspectives in Preclinical and Clinical Research

2020 ◽  
Vol 21 (24) ◽  
pp. 9646
Author(s):  
Clarissa Berardo ◽  
Laura Giuseppina Di Pasqua ◽  
Marta Cagna ◽  
Plinio Richelmi ◽  
Mariapia Vairetti ◽  
...  
Keyword(s):  
Liver Disease ◽  
Fatty Liver ◽  
Nonalcoholic Fatty Liver Disease ◽  
Fatty Liver Disease ◽  
Health Concern ◽  
In Vivo Models ◽  
Nonalcoholic Fatty Liver ◽  
Viral Hepatitis C

Nonalcoholic fatty liver disease (NAFLD) is a continuum of liver abnormalities often starting as simple steatosis and to potentially progress into nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis and hepatocellular carcinoma. Because of its increasing prevalence, NAFLD is becoming a major public health concern, in parallel with a worldwide increase in the recurrence rate of diabetes and metabolic syndrome. It has been estimated that NASH cirrhosis may surpass viral hepatitis C and become the leading indication for liver transplantation in the next decades. The broadening of the knowledge about NASH pathogenesis and progression is of pivotal importance for the discovery of new targeted and more effective therapies; aim of this review is to offer a comprehensive and updated overview on NAFLD and NASH pathogenesis, the most recommended treatments, drugs under development and new drug targets. The most relevant in vitro and in vivo models of NAFLD and NASH will be also reviewed, as well as the main molecular pathways involved in NAFLD and NASH development.

In Vitro and in Vivo Single-Agent Efficacy of Checkpoint Kinase 1 (Chk1) and 2 (Chk2) Inhibitor PF-0477736 (Pfizer) in B- and T-Acute Lymphoblastic Leukemia (ALL)

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1496-1496 ◽  
Author(s):  
Ilaria Iacobucci ◽  
Andrea Ghelli Luserna Di Rorà ◽  
Maria Vittoria Verga Falzacappa ◽  
Enrico Derenzini ◽  
Anna Ferrari ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Western Blot ◽  
Cell Lines ◽  
Single Agent ◽  
Time Dependent ◽  
Leukemia Cells ◽  
In Vivo Models

Abstract Abstract 1496 Introduction: Although progress in the treatment of ALL has been remarkable in children, in adults ALL still carries a dismal outcome. Thus, there is a need to improve therapeutic options. In the last years, selective inhibitors of Chk1 and/or Chk2 have been discovered, developed and entered in clinical trials. However, so far, they have not yet been investigated in leukemia. Chk1 and Chk2 are serine/threonine kinases that play a critical role in response to DNA damage both by halting the cell cycle through checkpoint activation and by actively repairing DNA. Here, we explored the in vitro and in vivo activity of single-agent inhibition of Chk1/2 by PF-0477736 in B- and T-progenitor ALL and we investigated potential biomarkers of functional inhibition. Methods: Human B (BCR-ABL1-positive: BV-173, SUPB-15; BCR-ABL1- negative: NALM-6, NALM-19, REH) and T (MOLT-4, RPMI-8402, CEM) leukemia cell lines were incubated with increasing concentrations of drug (5–2000 nM) for 24, 48 and 72 hours (hrs). Results: Inhibition of Chk1/2 resulted in a dose and time-dependent cytotoxicity with RPMI-8402 and BV-173 cells being the most sensitive (IC50 at 24 hrs: 57 nM and 82 nM, respectively), while NALM-6 cells the most resistant (IC50 at 24 hrs: 1426 nM)(WST-1 assay, Roche). Sensitivity did not correlate with p53 status (BV-173, SUPB-15, NALM-6 and NALM-19 cells were p53 wild-type whereas REH, MOLT-4, RPMI-8402 and CEM cells were p53 mutated) and with baseline levels of Chk1/2 and ATR/ATM phosphorylation, indicative of intrinsic genetic stress. Consistent with the viability results, Annexin V/Propidium Iodide (PI) staining analysis showed a significant increase of apoptosis at 24 and 48 hrs in a dose and time dependent manner coupled to increased proteolytic cleavage of PARP-1. In all sensitive cell lines in addition to the induction of apoptosis, Chk1/Chk2 inhibition induced DNA damage as demonstrated by the increased number of γH2AX foci (western blot and immunofluorescence analysis) and by a marked phosphorylation of Chk1 (ser317 and ser345). Moreover, PF-0477736 efficiently triggered the Chk1-Cdc25-Cdk1 pathway as soon as 24 hrs of treatment with a decrease of the inhibitory phosphorylation of Cdc25c (ser216) and Cdk1 (tyr15), leading to the abrogation of cell cycle arrest as confirmed by PI staining analysis at 6 and 24 hrs. The efficacy of PF-0477736 was thereafter demonstrated in primary leukemic blasts separated from 14 ALL patients. Based on the viability results at 24 hrs, 3 groups of patients were identified: very good responders, 5/14, 36% (IC50: 100–500 nM); good responders, 6/14, 43% (IC50: 600–1000 nM); poor responders, 3/14, 21% (IC50 > 1000 nM). By contrast, PF-0477736 did not show efficacy in primary cultures of normal bone marrow mononuclear cells, demonstrating its specificity for leukemia cells. We extended the in vitro and ex-vivo studies by assessing the efficacy of Chk inhibition in mice transplanted with T-lymphoid leukemia, demonstrating that PF-0477736 increases the survival of treated mice compared with mice treated with vehicle (p = 0.0016). Finally, in order to elucidate the mechanisms of action of PF-0477736 and to determine biomarkers of response, gene expression profiling analysis (Affymetrix GeneChip Human Gene 1.0 ST) was performed on treated leukemia cells and their untreated counterparts (DMSO 0.1%) after 24 hrs of incubation with concentrations equal to the IC50. Treatment resulted in a differential expression (p < 0.05) of genes involved in chromatin assembly, nucleosome organization and DNA packaging (e.g. Histone H1-H2A, 2B family clusters), DNA damage (DDIT3, GADD34 and GADD45a) and apoptosis (e.g. CDKN1A, BAX, FAS, BTG1), confirming that PF-0477736 contributes to checkpoint replication abrogation, accumulation of DNA damage and subsequent apoptosis in leukemia cells. Interestingly, N-Myc and c-Myc expression strongly decreased after treatment, as also confirmed by western blot analysis, suggesting that a negative feedback loop may exist between Chk induction and Myc expression. Conclusions: Together, these results demonstrate the efficacy of PF-0477736 both in vitro and in vivo models of ALL, arguing in favor of its future clinical evaluation in leukemia. Supported by ELN, AIL, AIRC, Fondazione Del Monte di Bologna-Ravenna, PRIN2009, PIO program, Programma Ricerca Regione-Università 2007–2009. PF-0477736 provided by Pfizer. Disclosures: Baccarani: ARIAD, Novartis, Bristol Myers-Squibb, and Pfizer: Consultancy, Honoraria, Speakers Bureau. Martinelli:NOVARTIS: Consultancy, Honoraria, Speakers Bureau; BMS: Consultancy, Honoraria, Speakers Bureau; PFIZER: Consultancy; ARIAD: Consultancy.

Targeting BET proteins in melanoma: A novel treatment approach.

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. 9091-9091
Author(s):  
Luca Paoluzzi ◽  
Miguel F. Segura ◽  
Barbara Fontanals-Cirera ◽  
Avital Gaziel-Sovran ◽  
Maria V Guijarro ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Melanoma Cell ◽  
Statistical Significance ◽  
Melanoma Cells ◽  
Western Blots ◽  
In Vivo Models ◽  
Mutational Status ◽  
Bet Inhibitors

9091 Background: Manipulation of key epigenetic regulators in melanoma proliferation is emerging as a new therapeutic strategy. Bromodomain-containing proteins such as the extraterminal domain (BET) family are components of transcription factor complexes and determinants of epigenetic memory. We investigated the expression of BRD4, a BET family member in melanoma cell lines and tissues, and the effects of its inhibition with the small molecule compounds MS436 and MS417 in in vitro and in vivo models of melanoma. Methods: BRD2 and BRD4 expression were analyzed by immunohistochemistry. We tested the effects of pharmacological or RNAi-mediated inhibition of BRD4 in melanoma cells using crystal violet-based assays for proliferation/colony formation and flow-cytometry for cell cycle analysis. The molecular effects of BRD4 suppression were examined using RNA sequencing, Real-Time quantitative PCR and western blots for p27, p21, MYC, ERK1 and SKP2. In the in vivo xenograft experiments NOD/SCID/IL2γR-/-mice were injected with melanoma cells and treated with MS417. Statistical significance was determined by unpaired t-test (GraphPad). Results: BRD4 was found significantly upregulated in primary and metastatic melanoma tissues compared to melanocytes and nevi (p<0.001). Treatment with BET inhibitors impaired melanoma cell proliferation in vitro and tumor growth and metastatic behavior in vivo, effects that were mostly recapitulated by individual silencing of BRD4. Rapidly after BET displacement, key cell cycle genes (SKP2, ERK1 and c-MYC) were downregulated concomitantly with the accumulation of CDK inhibitors (p21, p27), followed by melanoma cell cycle arrest. BET inhibitor efficacy was not influenced by BRAF or NRAS mutational status. Conclusions: Our results demonstrate for the first time a role for BRD4 in melanoma maintenance and support the role of BET proteins as novel targets in melanoma. Further investigation in the clinical setting is warranted.

scholarly journals Motor domain phosphorylation and regulation of the Drosophila kinesin 13, KLP10A

2009 ◽  
Vol 186 (4) ◽  
pp. 481-490 ◽  
Author(s):  
Vito Mennella ◽  
Dong-Yan Tan ◽  
Daniel W. Buster ◽  
Ana B. Asenjo ◽  
Uttama Rath ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Cell Cycle ◽  
Molecular Dynamics ◽  
Drosophila Melanogaster ◽  
Structural Features ◽  
Motor Domain ◽  
Α Helix ◽  
Dynamics Simulations

Microtubule (MT)-destabilizing kinesin 13s perform fundamental roles throughout the cell cycle. In this study, we show that the Drosophila melanogaster kinesin 13, KLP10A, is phosphorylated in vivo at a conserved serine (S573) positioned within the α-helix 5 of the motor domain. In vitro, a phosphomimic KLP10A S573E mutant displays a reduced capacity to depolymerize MTs but normal affinity for the MT lattice. In cells, replacement of endogenous KLP10A with KLP10A S573E dampens MT plus end dynamics throughout the cell cycle, whereas a nonphosphorylatable S573A mutant apparently enhances activity during mitosis. Electron microscopy suggests that KLP10A S573 phosphorylation alters its association with the MT lattice, whereas molecular dynamics simulations reveal how KLP10A phosphorylation can alter the kinesin–MT interface without changing important structural features within the motor’s core. Finally, we identify casein kinase 1α as a possible candidate for KLP10A phosphorylation. We propose a model in which phosphorylation of the KLP10A motor domain provides a regulatory switch controlling the time and place of MT depolymerization.

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