Papers by Marcos Malumbres
The Journal of clinical investigation, Jan 29, 2018
MASTL, a Ser/Thr kinase that inhibits PP2A-B55 complexes during mitosis, is mutated in autosomal ... more MASTL, a Ser/Thr kinase that inhibits PP2A-B55 complexes during mitosis, is mutated in autosomal dominant thrombocytopenia. However, the connections between the cell-cycle machinery and this human disease remain unexplored. We report here that, whereas Mastl ablation in megakaryocytes prevented proper maturation of these cells, mice carrying the thrombocytopenia-associated mutation developed thrombocytopenia as a consequence of aberrant activation and survival of platelets. Activation of mutant platelets was characterized by hyperstabilized pseudopods mimicking the effect of PP2A inhibition and actin polymerization defects. These aberrations were accompanied by abnormal hyperphosphorylation of multiple components of the actin cytoskeleton and were rescued both in vitro and in vivo by inhibiting upstream kinases such as PKA, PKC, or AMPK. These data reveal an unexpected role of Mastl in actin cytoskeletal dynamics in postmitotic cells and suggest that the thrombocytopenia-associated ...
Current Biology
Helfrid (2018) Two interlinked bistable switches govern mitotic control in mammalian cells. Curre... more Helfrid (2018) Two interlinked bistable switches govern mitotic control in mammalian cells. Current Biology, 28 (23). 3824-3832.e6.
BMC cancer, Apr 16, 2018
Precursor T-cell lymphoblastic lymphomas (T-LBL) are rare aggressive hematological malignancies t... more Precursor T-cell lymphoblastic lymphomas (T-LBL) are rare aggressive hematological malignancies that mainly develop in children. As in other cancers, the loss of cell cycle control plays a prominent role in the pathogenesis in these malignancies that is primarily attributed to loss of CDKN2A (encoding protein p16INK4A). However, the impact of the deregulation of other genes such as CDKN1C, E2F1, and TP53 remains to be clarified. Interestingly, experiments in mouse models have proven that conditional T-cell specific deletion of Cdkn1c gene may induce a differentiation block at the DN3 to DN4 transition, and that the loss of this gene in the absence of Tp53 led to aggressive thymic lymphomas. In this manuscript, we demonstrated that the simultaneous deregulation of CDKN1C, E2F1, and TP53 genes by epigenetic mechanisms and/or the deregulation of specific microRNAs, together with additional impairing of TP53 function by the expression of dominant-negative isoforms are common features in...
Current biology : CB, Jan 22, 2017
In mammalian females, germ cells remain arrested as primordial follicles. Resumption of meiosis i... more In mammalian females, germ cells remain arrested as primordial follicles. Resumption of meiosis is heralded by germinal vesicle breakdown, condensation of chromosomes, and their eventual alignment on metaphase plates. At the first meiotic division, anaphase-promoting complex/cyclosome associated with Cdc20 (APC/C(Cdc20)) activates separase and thereby destroys cohesion along chromosome arms. Because cohesion around centromeres is protected by shugoshin-2, sister chromatids remain attached through centromeric/pericentromeric cohesin. We show here that, by promoting proteolysis of cyclins and Cdc25B at the germinal vesicle (GV) stage, APC/C associated with the Cdh1 protein (APC/C(Cdh1)) delays the increase in Cdk1 activity, leading to germinal vesicle breakdown (GVBD). More surprisingly, by moderating the rate at which Cdk1 is activated following GVBD, APC/C(Cdh1) creates conditions necessary for the removal of shugoshin-2 from chromosome arms by the Aurora B/C kinase, an event crucia...
Cell, Jan 15, 2017
During mitosis, a cell divides its duplicated genome into two identical daughter cells. This proc... more During mitosis, a cell divides its duplicated genome into two identical daughter cells. This process must occur without errors to prevent proliferative diseases (e.g., cancer). A key mechanism controlling mitosis is the precise timing of more than 32,000 phosphorylation and dephosphorylation events by a network of kinases and counterbalancing phosphatases. The identity, magnitude, and temporal regulation of these events have emerged recently, largely from advances in mass spectrometry. Here, we show phosphoevents currently believed to be key regulators of mitosis. For an animated version of this SnapShot, please see http://www.cell.com/cell/enhanced/odonoghue2.
Nat Genet, 2003
CDK2 (refs. 1,2) is thought to be essential in the mammalian cell cycle by driving cells through ... more CDK2 (refs. 1,2) is thought to be essential in the mammalian cell cycle by driving cells through the G1/S transition (in association with Etype cyclins) and allowing them to progress through the S phase (in association with A-type cyclins). Whereas A-cyclins (A1 and A2) can also associate with the mitotic CDK1 kinase, CDK2 is the only known catalytic partner for E-cyclins (E1 and E2; ref. 3). The precise identity of the physiologically relevant substrates for CDK2 is controversial. Yet, it is well established that CDK2-cyclin E complexes are responsible for completing the inactivation of retinoblastoma (Rb), a step thought to be necessary for initiation of DNA synthesis 4. Other proposed targets of CDK2-cyclin E include the transcription factor E2F-5 (ref. 5); CDC6, a preinitiation factor essential for generating functional DNA replication origins 6 ; p220NPAT, a protein involved in S phase-specific histone gene transcription 7,8 ; nucleophosmin (NPM/B23) and MPS1, two proteins presumably involved in centrosome duplication 9,10 ; and its own inhibitor, p27 (also called Kip1), which is then targeted for degradation 11,12. Loading of CDC45 onto replication origins, a prerequisite for recruitment of DNA polymerase to DNA initiation complexes, also seems to depend on CDK2-cyclin E activity 13. It is therefore believed that initiation of DNA replication requires a peak of CDK2 activity accomplished by accumulation of cyclin E levels and concomitant disappearance of p27. Once S phase has started, cyclin E is autophosphorylated by the CDK2-cyclin E complex. Phosphorylated cyclin E is recognized by the F-box protein FBW7 (also called hCDC4 and AGO) and targeted for destruction by the SCF proteosome 14. Degradation of cyclin E allows CDK2 to bind to its second partner, A-type cyclins. CDK2-cyclin A phosphorylates CDC6 inducing its translocation from the nucleus to the cytoplasm, an event that has been implicated in preventing reinitiation of DNA replication during the S and G2 phases of the cell cycle 15. CDK2-cyclin A also phosphorylates CDH1, one of the ubiquitin ligase components of the anaphase-promoting complex (APC) required for degradation of cyclin B1. Phosphorylation of CDH1 induces its release from the APC, leading to an increase in cyclin B1 levels required for progression through the G2/M transition 16. CDK2-cyclin A complexes have also been proposed to have a key role in centrosome duplication 17. These observations strongly suggest that CDK2 must be essential for cell proliferation. Moreover, early studies have shown that dominant-negative mutants of CDK2, antibodies against CDK2, cyclin E or cyclin A, and Cdk2 antisense RNA block DNA synthesis or cell proliferation 18-22. These observations have been recently challenged 23 , however, by the finding that certain cancer cells proliferate despite CDK2 inhibition. To better understand the function of CDK2 in cell proliferation, not only in cultured cells but also in such complex organisms as mice, we targeted the Cdk2 locus by homologous recombination in ES cells. Here, we report that ablation of Cdk2 in the germ line of mice does not have substantial consequences for embryonic or postnatal development, except in germ cells. Analysis of mouse embryonic fibroblasts (MEFs) indicates that CDK2 is dispensable for cell cycle progression and proliferation but has an unanticipated role in meiotic cell division. RESULTS Generation of mice lacking CDK2 To target the mouse Cdk2 locus, we knocked-in two loxP sites flanking coding exons 2 and 3 of Cdk2 by homologous recombination in ES cells (Fig. 1). Removal of these sequences by a Cre recombinase eliminates the PSTAIRE cyclin-binding domain. Moreover, splicing from
Clinical Translational Oncology, Mar 1, 1999
Expert Opinion on Therapeutic Targets, Sep 9, 2014
Aurora proteins are serine/threonine kinases with critical functions during mitosis. Aurora A, on... more Aurora proteins are serine/threonine kinases with critical functions during mitosis. Aurora A, one of the members of this family, participates in crucial processes including mitotic entry, DNA damage checkpoint recovery and centrosome and spindle maturation. Aurora A is frequently overexpressed in human cancers and, when inhibited, impairs cell proliferation. Here, we review the preclinical studies that support the use of Aurora A inhibitors in antitumoral strategies. We also discuss past or current clinical trials using Aurora A inhibitors in multiple tumor types. We pay special attention to Alisertib, a potent and selective Aurora A inhibitor currently in Phase III. The potential of Aurora A inhibitors in the treatment of cancer depends on many factors, mainly related with the molecular status of tumor cells. Yet, we still need to find proper biomarkers to select those patients that better react to Aurora A inhibitors. Furthermore, their effect could significantly improve when used in combination with other drugs. Although some clinical trials are already testing the cooperative effect of different antitumoral drugs, additional preclinical studies are necessary to establish the best combinations. Here, we discuss some possibilities that could be explored in future studies.
Mamm Genome, 1998
The cyclin-dependent kinase inhibitors p15 INK4b and p16 INK4a are involved in the development of... more The cyclin-dependent kinase inhibitors p15 INK4b and p16 INK4a are involved in the development of a wide range of human and murine tumors. These tumor suppressor genes are inactivated by deletions frequently associated to point mutations in the coding regions or hypermethylation of their promoters. In this work, we describe a simple-sequence length polymorphism located in mouse Chromosome (Chr) 4, between the Cdkn2B (p15 INK4b) and Cdkn2A (p16 INK4a) genes, only 700 bp downstream of the Cdkn2B locus. This DNA region was analyzed in different inbred strains showing a variable AC-repetitive DNA sequence. We used this microsatellite to detect loss of heterozygosity of the Cdkn2A and Cdkn2B loci in ␥-irradiation-induced thymic lymphomas of C57BL/6J × RF/J F 1 hybrids. Using this specific marker, we were able to locate additional allelic losses not detected by other microsatellites. Since the allelic losses can be detected by a simple PCR amplification, this AC-repetitive sequence is specially useful as a genetic marker for these Cdkn2 genes and specifically for the p15 INK4b cell cycle inhibitor.
ABSTRACT Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Medicina,... more ABSTRACT Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Medicina, Departamento de Bioquímica. Fecha de lectura: 22 de Julio de 2009 Bibliografía p. 121-137
Nature Cell Biology, May 30, 2014
mutual cooperation between all three emergent lineages of the blastocyst is a requisite for the c... more mutual cooperation between all three emergent lineages of the blastocyst is a requisite for the correct execution of the developmental program. This cooperation leads to the timely specification of the two ICM lineages, and the progression of epiblast progenitors from a naive to a primed state of pluripotency.
ABSTRACT Tesis doctoral inédita realizada en la Universidad Autónoma de Madrid. Facultad de Medic... more ABSTRACT Tesis doctoral inédita realizada en la Universidad Autónoma de Madrid. Facultad de Medicina, Departamento de Bioquímica. Fecha de lectura: 16 de Noviembre de 2010.
Oncogene, 2003
Lack of Cdk4 expression in mice leads to insulin-deficient diabetes and female infertility owing ... more Lack of Cdk4 expression in mice leads to insulin-deficient diabetes and female infertility owing to a reduced number of pancreatic b cells and prolactin-producing pituitary lactotrophs, respectively. Cdk4 null mice display also reduced body and organ size. Here, we show that Cdk4 is essential for the postnatal proliferation of pancreatic b cells but not for embryonic neogenesis from ductal epithelial cells. Re-expression of endogenous Cdk4 in b cells and in the pituitary gland of Cdk4 null mice restores cell proliferation and results in fertile and normoglycemic animals, thus, demonstrating that the proliferation defects in these cellular populations are cell autonomous because of the lack of Cdk4 expression. However, these mice remain small in size, indicating that this phenotype is not because of pancreatic-or pituitarymediated endocrine defects. This phenotype is a consequence of reduced cell numbers rather than reduced cell size. Thus, mammalian Cdk4 is not only involved in controlling proliferation of specific cell types but may play a wider role in establishing homeostatic cell numbers.
Cell research, Jun 29, 2016
Craniofacial anomalies (CFAs) characterized by birth defects of skull and facial bones are the mo... more Craniofacial anomalies (CFAs) characterized by birth defects of skull and facial bones are the most frequent congenital disease. Genomic analysis has identified multiple genes responsible for CFAs; however, the underlying genetic mechanisms for the majority of CFAs remain largely unclear. Our previous study revealed that the Wwp2 E3 ubiquitin ligase facilitates craniofacial development in part through inducing monoubiquitination and activation of the paired-like homeobox transcription factor, Goosecoid (Gsc). Here we report that Gsc is also ubiquitinated and activated by the APC(Cdh1) E3 ubiquitin ligase, leading to transcriptional activation of various Gsc target genes crucial for craniofacial development. Consistenly, neural crest-specific Cdh1-knockout mice display similar bone malformation as Wwp2-deficient mice in the craniofacial region, characterized by a domed skull, a short snout and a twisted nasal bone. Mechanistically, like Wwp2-deficient mice, mice with Cdh1 deficiency ...
Cell Discovery, 2016
inhibits WWP2-mediated ubiquitination of PTEN to suppress tumorigenesis in an APC-independent man... more inhibits WWP2-mediated ubiquitination of PTEN to suppress tumorigenesis in an APC-independent manner." Cell Discovery 2 (1): 15044.
Biochimica Et Biophysica Acta Cr Reviews on Cancer, Mar 14, 2002
The Cyclin D-Cdk4,6/INK4/Rb/E2F pathway plays a key role in controlling cell growth by integratin... more The Cyclin D-Cdk4,6/INK4/Rb/E2F pathway plays a key role in controlling cell growth by integrating multiple mitogenic and antimitogenic stimuli. The components of this pathway are gene families with a high level of structural and functional redundancy and are expressed in an overlapping fashion in most tissues and cell types. Using classical transgenic technology as well as gene-targeting in ES cells, a series of mouse models have been developed to study the in vivo function of individual components of this pathway in both normal homeostasis and tumor development. These models have proven to be useful to define specific as well as redundant roles among members of these cell cycle regulatory gene families. This pathway is deregulated in the vast majority of human tumors by genetic and epigenetic alterations that target at least some of its key members such as Cyclin D1, Cdk4, INK4a and INK4b, pRb etc. As a consequence, some of these molecules are currently being considered as targets for cancer therapy, and several novel molecules, such as Cdk inhibitors, are under development as potential anti-cancer drugs.
Oncotarget, Jan 23, 2016
The transcription factor TAL1 is a proto-oncogene whose aberrant expression in committed T-cell p... more The transcription factor TAL1 is a proto-oncogene whose aberrant expression in committed T-cell precursors is associated with the development of T-cell acute lymphoblastic leukemia (T-ALL). The mechanisms leading to aberrant activation of TAL1 in T-ALL patients who lack chromosomal rearrangements involving the TAL1 locus remain largely unknown. We hypothesized that TAL1 levels decrease during normal T-cell development at least in part due to miRNA-dependent silencing, in which case TAL1 over-expression in some T-ALL cases could be the consequence of deregulated miRNA expression. By performing computational prediction of miRNAs that bind to the human TAL1 mRNA we compiled a list of miRNAs that are candidates to regulate TAL1. Using a luciferase reporter system and mutagenesis assays we confirmed the miRNA-TAL1 mRNA interactions and selected candidate miRNAs: miR-101, miR-520d-5p, miR-140-5p, miR-448 and miR-485-5p. Over-expression of these microRNAs in different T-ALL cell lines cons...
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Papers by Marcos Malumbres