Cristina Lira - Academia.edu (original) (raw)

Papers by Cristina Lira

Biochemical and Biophysical Research Communications, 2007

Biochemical and Biophysical Research Communications, 2007

Sirtuin proteins form a family of NAD +-dependent protein deacetylases that are considered potent... more Sirtuin proteins form a family of NAD +-dependent protein deacetylases that are considered potential drug targets against parasites. Here, we present the first characterization of a sirtuin orthologue from Leishmania amazonensis, an aetiological agent of American tegumentary leishmaniasis that has been the subject of many studies focused in the development of therapeutic approaches. The protein has high sequence identity with other Kinetoplastid Silent information regulator 2 Related Protein 1 (Sir2RP1) and was named LaSir2RP1. The gene exists as a single copy, encoding a monomeric protein (LaSir2RP1) of approximately 41 kDa that has NAD +-dependent deacetylase activity. LaSir2RP1 was immunodetected in total protein extracts, in cytoplasmic granules, and in the secreted material of both promastigotes and lesion-derived amastigotes. Analysis of both lectin-affinity purified promastigote and amastigote extracts revealed the presence of a major enriched protein of approximately 66 kDa that was recognized by an anti-LaSir2RP1 serum, suggesting that a parasite sirtuin could be glycosylated in vivo.

Biochimica et biophysica acta, Nov 24, 2017

Leishmania spp. telomeres are composed of 5'-TTAGGG-3' repeats associated with proteins. ... more Leishmania spp. telomeres are composed of 5'-TTAGGG-3' repeats associated with proteins. We have previously identified LaRbp38 and LaRPA-1 as proteins that bind the G-rich telomeric strand. At that time, we had also partially characterized a protein:DNA complex, named LaGT1, but we could not identify its protein component. Using protein-DNA interaction and competition assays, we confirmed that LaGT1 is highly specific to the G-rich telomeric single-stranded DNA. Three protein bands, with LaGT1 activity, were isolated from affinity-purified protein extracts in-gel digested, and sequenced de novo using mass spectrometry analysis. In silico analysis of the digested peptide identified them as a putative calmodulin with sequences identical to the T. cruzi calmodulin. In the Leishmania genome, the calmodulin ortholog is present in three identical copies. We cloned and sequenced one of the gene copies, named it LCalA, and obtained the recombinant protein. Multiple sequence alignmen...

Protein Expression and Purification, 2008

Osteoblast cadherin (OB-cadherin, also known as cadherin-11) is a Ca 2+-dependent homophilic cell... more Osteoblast cadherin (OB-cadherin, also known as cadherin-11) is a Ca 2+-dependent homophilic cell adhesion molecule that is expressed mainly in osteoblasts. OB-cadherin is expressed in prostate cancer and may be involved in the homing of metastatic prostate cancer cells to bone. The extracellular domain of OB-cadherin may be used to inhibit the adhesion between prostate cancer cells and osteoblasts. In this report, we describe the expression of the extracellular domain of OBcadherin as an Fc fusion protein (OB-CAD-Fc) in human embryonic kidney 293FT cells using a bicistronic retroviral vector. Coexpression of GFP and OB-CAD-Fc through the bicistronic vector permitted enrichment of OB-CAD-Fc-expressing cells by fluorescence-activated cell sorting. Recombinant OB-CAD-Fc proteins were secreted into cell medium, and about 0.85 mg of purified OB-CAD-Fc protein was purified from 1 liter of the conditioned medium using immobilized protein A-affinity chromatography. The purified OB-CAD-Fc was biologically active because it supported the adhesion of PC3 cells and L cells transduced with OB-cadherin. The availability of OB-CAD-Fc offers opportunities to test whether OB-CAD-Fc can be used to inhibit OB-cadherin-mediated prostate cancer bone metastasis in vivo or to generate antibodies for inhibiting the adhesion between prostate cancer cells and osteoblasts.

Parasitology Research, 2006

The Leishmania amazonensis telomerase gene was cloned by a polymerase chain reaction-based strate... more The Leishmania amazonensis telomerase gene was cloned by a polymerase chain reaction-based strategy using primers designed from a Leishmania major sequence that shared similarities with conserved telomerase motifs. The genes from three other species were cloned for comparative purposes. A ClustalW multiple-sequence alignment demonstrated that the Leishmania telomerases show greater homology with each other than with the proteins of other kinetoplastids and eukaryotes. Characterization experiments indicated that the putative Leishmania telomerase gene was probably in single copy and located in the largest chromosomes. A single messenger ribonucleic acid transcript was found in promastigotes. Phylogenetic analysis suggested that Leishmania telomerase might represent a liaison between the oldest and the newest branches of telomerases.

Experimental Parasitology, 2011

Telomeres are protein-DNA complexes that protect chromosome ends from degradation and fusion. In ... more Telomeres are protein-DNA complexes that protect chromosome ends from degradation and fusion. In Leishmania spp., telomeric DNA comprises a conserved TTAGGG repeat and is maintained by telomerase. Telomerase is a multisubunit enzymatic complex that ensures the complete DNA replication by adding new telomeric repeats to the G-rich strand. In this report we aimed to purify and study the biochemical properties of Leishmani amazonensis telomerase. In a first trial we used affinity chromatography with antisense 2 0-O-methyl oligonucleotide without success since the Leishmania telomerase, similarly to Trypanosoma cruzi enzyme, was not eluted by competition, but instead, it remained bound to the column. Partially purified L. amazonensis telomerase activity was achieved by fractionation of extracts on complementary ion exchange and Heparin columns. Further purification of these fractions on a G-rich telomeric DNA affinity chromatography enriched for telomerase activity. The knowledge of telomerase characteristics in Leishmania could help to develop new strategies to overcome leishmaniasis.

Cancer Research, 2010

Cell adhesion molecules have been implicated in the colonization of cancer cells to distant organ... more Cell adhesion molecules have been implicated in the colonization of cancer cells to distant organs. Prostate cancer (PCa) has a propensity to metastasize to bone and cadherin-11, which is an osteoblast cadherin aberrantly expressed in PCa cells derived from bone metastases, has been shown to play a role in the metastasis of PCa cells to bone. However, the mechanism by which cadherin-11 is involved in this process is not known. Here, we show that expression of cadherin-11 in cadherin-11-negative C4-2B4 cells increases their spreading and intercalation into an osteoblast layer, and also stimulates C4-2B4 cell migration and invasiveness. Downregulation of cadherin-11 in cadherin-11-expressing metastatic PC3 cells decreases cell motility and invasiveness. Further, both the juxtamembrane (JMD) and β-catenin binding domains (CBS) in the cytoplasmic tail of cadherin-11 are required for cell migration and invasion, but not spreading. Gene array analyses showed that several invasion related genes, including MMP-7 and MMP-15, are upregulated in cadherin-11, but not in cad11-ΔJMD or cad11-ΔCBS, expressing C4-2B4 cells. These observations suggest that cadherin-11 not only provides a physical link between PCa cells and osteoblasts but also increases PCa cell motility and invasiveness that may facilitate the metastatic colonization of PCa cells in bone.

Archives of biochemistry …, 2007

Different species of Leishmania can cause a variety of medically important diseases, whose contro... more Different species of Leishmania can cause a variety of medically important diseases, whose control and treatment are still health problems. Telomere binding proteins (TBPs) have potential as targets for anti-parasitic chemotherapy because of their importance for genome ...

Trends in Parasitology, 2007

Studies of telomere structure and maintenance in trypanosomatids have provided insights into the ... more Studies of telomere structure and maintenance in trypanosomatids have provided insights into the evolutionary origin and conservation of some telomeric components shared by trypanosomes and vertebrates. For example, trypanosomatid telomeres are maintained by telomerase and consist of the canonical TTAGGG repeats, which in Trypanosoma brucei can form telomeric loops (t-loops). However, the telomeric chromatin of trypanosomatids is composed of organism-specific proteins and other proteins that share little sequence similarity with their vertebrate counterparts. Because telomere maintenance mechanisms are essential for genome stability, we propose that the particular features shown by the trypanosome telomeric chromatin hold the key for the design of antiparasitic drugs.

Biochemical and Biophysical Research Communications, 2007

Replication protein A (RPA) is a highly conserved heterotrimeric single-stranded DNA-binding prot... more Replication protein A (RPA) is a highly conserved heterotrimeric single-stranded DNA-binding protein involved in different events of DNA metabolism. In yeast, subunits 1 (RPA-1) and 2 (RPA-2) work also as telomerase recruiters and, in humans, the complex unfolds G-quartet structures formed by the 3' G-rich telomeric strand. In most eukaryotes, RPA-1 and RPA-2 bind DNA using multiple OB fold domains. In trypanosomatids, including Leishmania, RPA-1 has a canonical OB fold and a truncated RFA-1 structural domain. In Leishmania amazonensis, RPA-1 alone can form a complex in vitro with the telomeric G-rich strand. In this work, we show that LaRPA-1 is a nuclear protein that associates in vivo with Leishmania telomeres. We mapped the boundaries of the OB fold DNA-binding domain using deletion mutants. Since Leishmania and other trypanosomatids lack homologues of known telomere end binding proteins, our results raise questions about the function of RPA-1 in parasite telomeres.

Archives of Biochemistry and Biophysics, 2007

Different species of Leishmania can cause a variety of medically important diseases, whose contro... more Different species of Leishmania can cause a variety of medically important diseases, whose control and treatment are still health prob-14 lems. Telomere binding proteins (TBPs) have potential as targets for anti-parasitic chemotherapy because of their importance for genome 15 stability and cell viability. Here, we describe LaTBP1 a protein that has a Myb-like DNA-binding domain, a feature shared by most 16 double-stranded telomeric proteins. Binding assays using full-length and truncated LaTBP1 combined with spectroscopy analysis were 17 used to map the boundaries of the Myb-like domain near to the protein only tryptophan residue. The Myb-like domain of LaTBP1 con-18 tains a conserved hydrophobic cavity implicated in DNA-binding activity. A hypothetical model helped to visualize that it shares struc-19 tural homology with domains of other Myb-containing proteins. Competition assays and chromatin immunoprecipitation confirmed the 20 specificity of LaTBP1 for telomeric and GT-rich DNAs, suggesting that LaTBP1 is a new TBP. 21 Ó 2007 Published by Elsevier Inc.

Biochemical and Biophysical Research Communications, 2007

Leishmania amazonensis causes a wide spectrum of leishmaniasis. There are no vaccines or adequate... more Leishmania amazonensis causes a wide spectrum of leishmaniasis. There are no vaccines or adequate treatment for leishmaniasis, therefore there is considerable interest in the identification of new targets for anti-leishmania drugs. The central role of telomere-binding proteins in cell maintenance makes these proteins potential targets for new drugs. In this work, we used a combination of purification chromatographies to screen L. amazonensis proteins for molecules capable of binding double-stranded telomeric DNA. This approach resulted in the purification of a 38 kDa polypeptide that was identified by mass spectrometry as Rbp38, a trypanosomatid protein previously shown to stabilize mitochondrial RNA and to associate with nuclear and kinetoplast DNAs. Western blotting and supershift assays confirmed the identity of the protein as LaRbp38. Competition and chromatin immunoprecipitation assays confirmed that LaRbp38 interacted with kinetoplast and nuclear DNAs in vivo and suggested that LaRbp38 may have dual cellular localization and more than one function.

Biochemical and Biophysical Research Communications, 2007

Biochemical and Biophysical Research Communications, 2007

Sirtuin proteins form a family of NAD +-dependent protein deacetylases that are considered potent... more Sirtuin proteins form a family of NAD +-dependent protein deacetylases that are considered potential drug targets against parasites. Here, we present the first characterization of a sirtuin orthologue from Leishmania amazonensis, an aetiological agent of American tegumentary leishmaniasis that has been the subject of many studies focused in the development of therapeutic approaches. The protein has high sequence identity with other Kinetoplastid Silent information regulator 2 Related Protein 1 (Sir2RP1) and was named LaSir2RP1. The gene exists as a single copy, encoding a monomeric protein (LaSir2RP1) of approximately 41 kDa that has NAD +-dependent deacetylase activity. LaSir2RP1 was immunodetected in total protein extracts, in cytoplasmic granules, and in the secreted material of both promastigotes and lesion-derived amastigotes. Analysis of both lectin-affinity purified promastigote and amastigote extracts revealed the presence of a major enriched protein of approximately 66 kDa that was recognized by an anti-LaSir2RP1 serum, suggesting that a parasite sirtuin could be glycosylated in vivo.

Biochimica et biophysica acta, Nov 24, 2017

Leishmania spp. telomeres are composed of 5'-TTAGGG-3' repeats associated with proteins. ... more Leishmania spp. telomeres are composed of 5'-TTAGGG-3' repeats associated with proteins. We have previously identified LaRbp38 and LaRPA-1 as proteins that bind the G-rich telomeric strand. At that time, we had also partially characterized a protein:DNA complex, named LaGT1, but we could not identify its protein component. Using protein-DNA interaction and competition assays, we confirmed that LaGT1 is highly specific to the G-rich telomeric single-stranded DNA. Three protein bands, with LaGT1 activity, were isolated from affinity-purified protein extracts in-gel digested, and sequenced de novo using mass spectrometry analysis. In silico analysis of the digested peptide identified them as a putative calmodulin with sequences identical to the T. cruzi calmodulin. In the Leishmania genome, the calmodulin ortholog is present in three identical copies. We cloned and sequenced one of the gene copies, named it LCalA, and obtained the recombinant protein. Multiple sequence alignmen...

Protein Expression and Purification, 2008

Osteoblast cadherin (OB-cadherin, also known as cadherin-11) is a Ca 2+-dependent homophilic cell... more Osteoblast cadherin (OB-cadherin, also known as cadherin-11) is a Ca 2+-dependent homophilic cell adhesion molecule that is expressed mainly in osteoblasts. OB-cadherin is expressed in prostate cancer and may be involved in the homing of metastatic prostate cancer cells to bone. The extracellular domain of OB-cadherin may be used to inhibit the adhesion between prostate cancer cells and osteoblasts. In this report, we describe the expression of the extracellular domain of OBcadherin as an Fc fusion protein (OB-CAD-Fc) in human embryonic kidney 293FT cells using a bicistronic retroviral vector. Coexpression of GFP and OB-CAD-Fc through the bicistronic vector permitted enrichment of OB-CAD-Fc-expressing cells by fluorescence-activated cell sorting. Recombinant OB-CAD-Fc proteins were secreted into cell medium, and about 0.85 mg of purified OB-CAD-Fc protein was purified from 1 liter of the conditioned medium using immobilized protein A-affinity chromatography. The purified OB-CAD-Fc was biologically active because it supported the adhesion of PC3 cells and L cells transduced with OB-cadherin. The availability of OB-CAD-Fc offers opportunities to test whether OB-CAD-Fc can be used to inhibit OB-cadherin-mediated prostate cancer bone metastasis in vivo or to generate antibodies for inhibiting the adhesion between prostate cancer cells and osteoblasts.

Parasitology Research, 2006

The Leishmania amazonensis telomerase gene was cloned by a polymerase chain reaction-based strate... more The Leishmania amazonensis telomerase gene was cloned by a polymerase chain reaction-based strategy using primers designed from a Leishmania major sequence that shared similarities with conserved telomerase motifs. The genes from three other species were cloned for comparative purposes. A ClustalW multiple-sequence alignment demonstrated that the Leishmania telomerases show greater homology with each other than with the proteins of other kinetoplastids and eukaryotes. Characterization experiments indicated that the putative Leishmania telomerase gene was probably in single copy and located in the largest chromosomes. A single messenger ribonucleic acid transcript was found in promastigotes. Phylogenetic analysis suggested that Leishmania telomerase might represent a liaison between the oldest and the newest branches of telomerases.

Experimental Parasitology, 2011

Telomeres are protein-DNA complexes that protect chromosome ends from degradation and fusion. In ... more Telomeres are protein-DNA complexes that protect chromosome ends from degradation and fusion. In Leishmania spp., telomeric DNA comprises a conserved TTAGGG repeat and is maintained by telomerase. Telomerase is a multisubunit enzymatic complex that ensures the complete DNA replication by adding new telomeric repeats to the G-rich strand. In this report we aimed to purify and study the biochemical properties of Leishmani amazonensis telomerase. In a first trial we used affinity chromatography with antisense 2 0-O-methyl oligonucleotide without success since the Leishmania telomerase, similarly to Trypanosoma cruzi enzyme, was not eluted by competition, but instead, it remained bound to the column. Partially purified L. amazonensis telomerase activity was achieved by fractionation of extracts on complementary ion exchange and Heparin columns. Further purification of these fractions on a G-rich telomeric DNA affinity chromatography enriched for telomerase activity. The knowledge of telomerase characteristics in Leishmania could help to develop new strategies to overcome leishmaniasis.

Cancer Research, 2010

Cell adhesion molecules have been implicated in the colonization of cancer cells to distant organ... more Cell adhesion molecules have been implicated in the colonization of cancer cells to distant organs. Prostate cancer (PCa) has a propensity to metastasize to bone and cadherin-11, which is an osteoblast cadherin aberrantly expressed in PCa cells derived from bone metastases, has been shown to play a role in the metastasis of PCa cells to bone. However, the mechanism by which cadherin-11 is involved in this process is not known. Here, we show that expression of cadherin-11 in cadherin-11-negative C4-2B4 cells increases their spreading and intercalation into an osteoblast layer, and also stimulates C4-2B4 cell migration and invasiveness. Downregulation of cadherin-11 in cadherin-11-expressing metastatic PC3 cells decreases cell motility and invasiveness. Further, both the juxtamembrane (JMD) and β-catenin binding domains (CBS) in the cytoplasmic tail of cadherin-11 are required for cell migration and invasion, but not spreading. Gene array analyses showed that several invasion related genes, including MMP-7 and MMP-15, are upregulated in cadherin-11, but not in cad11-ΔJMD or cad11-ΔCBS, expressing C4-2B4 cells. These observations suggest that cadherin-11 not only provides a physical link between PCa cells and osteoblasts but also increases PCa cell motility and invasiveness that may facilitate the metastatic colonization of PCa cells in bone.

Archives of biochemistry …, 2007

Different species of Leishmania can cause a variety of medically important diseases, whose contro... more Different species of Leishmania can cause a variety of medically important diseases, whose control and treatment are still health problems. Telomere binding proteins (TBPs) have potential as targets for anti-parasitic chemotherapy because of their importance for genome ...

Trends in Parasitology, 2007

Studies of telomere structure and maintenance in trypanosomatids have provided insights into the ... more Studies of telomere structure and maintenance in trypanosomatids have provided insights into the evolutionary origin and conservation of some telomeric components shared by trypanosomes and vertebrates. For example, trypanosomatid telomeres are maintained by telomerase and consist of the canonical TTAGGG repeats, which in Trypanosoma brucei can form telomeric loops (t-loops). However, the telomeric chromatin of trypanosomatids is composed of organism-specific proteins and other proteins that share little sequence similarity with their vertebrate counterparts. Because telomere maintenance mechanisms are essential for genome stability, we propose that the particular features shown by the trypanosome telomeric chromatin hold the key for the design of antiparasitic drugs.

Biochemical and Biophysical Research Communications, 2007

Replication protein A (RPA) is a highly conserved heterotrimeric single-stranded DNA-binding prot... more Replication protein A (RPA) is a highly conserved heterotrimeric single-stranded DNA-binding protein involved in different events of DNA metabolism. In yeast, subunits 1 (RPA-1) and 2 (RPA-2) work also as telomerase recruiters and, in humans, the complex unfolds G-quartet structures formed by the 3' G-rich telomeric strand. In most eukaryotes, RPA-1 and RPA-2 bind DNA using multiple OB fold domains. In trypanosomatids, including Leishmania, RPA-1 has a canonical OB fold and a truncated RFA-1 structural domain. In Leishmania amazonensis, RPA-1 alone can form a complex in vitro with the telomeric G-rich strand. In this work, we show that LaRPA-1 is a nuclear protein that associates in vivo with Leishmania telomeres. We mapped the boundaries of the OB fold DNA-binding domain using deletion mutants. Since Leishmania and other trypanosomatids lack homologues of known telomere end binding proteins, our results raise questions about the function of RPA-1 in parasite telomeres.

Archives of Biochemistry and Biophysics, 2007

Different species of Leishmania can cause a variety of medically important diseases, whose contro... more Different species of Leishmania can cause a variety of medically important diseases, whose control and treatment are still health prob-14 lems. Telomere binding proteins (TBPs) have potential as targets for anti-parasitic chemotherapy because of their importance for genome 15 stability and cell viability. Here, we describe LaTBP1 a protein that has a Myb-like DNA-binding domain, a feature shared by most 16 double-stranded telomeric proteins. Binding assays using full-length and truncated LaTBP1 combined with spectroscopy analysis were 17 used to map the boundaries of the Myb-like domain near to the protein only tryptophan residue. The Myb-like domain of LaTBP1 con-18 tains a conserved hydrophobic cavity implicated in DNA-binding activity. A hypothetical model helped to visualize that it shares struc-19 tural homology with domains of other Myb-containing proteins. Competition assays and chromatin immunoprecipitation confirmed the 20 specificity of LaTBP1 for telomeric and GT-rich DNAs, suggesting that LaTBP1 is a new TBP. 21 Ó 2007 Published by Elsevier Inc.

Biochemical and Biophysical Research Communications, 2007

Leishmania amazonensis causes a wide spectrum of leishmaniasis. There are no vaccines or adequate... more Leishmania amazonensis causes a wide spectrum of leishmaniasis. There are no vaccines or adequate treatment for leishmaniasis, therefore there is considerable interest in the identification of new targets for anti-leishmania drugs. The central role of telomere-binding proteins in cell maintenance makes these proteins potential targets for new drugs. In this work, we used a combination of purification chromatographies to screen L. amazonensis proteins for molecules capable of binding double-stranded telomeric DNA. This approach resulted in the purification of a 38 kDa polypeptide that was identified by mass spectrometry as Rbp38, a trypanosomatid protein previously shown to stabilize mitochondrial RNA and to associate with nuclear and kinetoplast DNAs. Western blotting and supershift assays confirmed the identity of the protein as LaRbp38. Competition and chromatin immunoprecipitation assays confirmed that LaRbp38 interacted with kinetoplast and nuclear DNAs in vivo and suggested that LaRbp38 may have dual cellular localization and more than one function.