The Experts below are selected from a list of 7143 Experts worldwide ranked by ideXlab platform
Jordan A Shavit - One of the best experts on this subject based on the ideXlab platform.
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nfe2 is dispensable for early but required for adult thrombocyte formation and function in zebrafish
Blood Advances, 2018Co-Authors: Megan S Rost, Ilya Shestopalov, Andy H Vo, Catherine E Richter, Sylvia M Emly, Francesca G Barrett, David L Stachura, Michael Holinstat, Jordan A ShavitAbstract:The NFE2 transcription factor is expressed in multiple hematopoietic lineages with a well-defined role in regulating megakaryocyte biogenesis and platelet production in mammals. Mice deficient in NFE2 develop severe thrombocytopenia with lethality resulting from Neonatal Hemorrhage. Recent data in mammals reveal potential differences in embryonic and adult thrombopoiesis. Multiple studies in zebrafish have revealed mechanistic insights into hematopoiesis, although thrombopoiesis has been less studied. Rather than platelets, zebrafish possess thrombocytes, which are nucleated cells with similar functional properties. Using transcription activator-like effector nucleases to generate mutations in nfe2 , we show that unlike mammals, zebrafish survive to adulthood in the absence of Nfe2. Despite developing severe thrombocytopenia, homozygous mutants do not display overt Hemorrhage or reduced survival. Surprisingly, quantification of circulating thrombocytes in mutant 6-day-old larvae revealed no significant differences from wild-type siblings. Both wild-type and nfe2 null larvae formed thrombocyte-rich clots in response to endothelial injury. In addition, ex vivo thrombocytic colony formation was intact in nfe2 mutants, and adult kidney marrow displayed expansion of hematopoietic progenitors. These data suggest that loss of Nfe2 results in a late block in adult thrombopoiesis, with secondary expansion of precursors: features consistent with mammals. Overall, our data suggest parallels with erythropoiesis, including distinct primitive and definitive pathways of development and potential for a previously unknown Nfe2-independent pathway of embryonic thrombopoiesis. Long-term homozygous mutant survival will facilitate in-depth study of Nfe2 deficiency in vivo, and further investigation could lead to alternative methodologies for the enhancement of platelet production.
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nfe2 is dispensable for early but required for adult thrombocyte formation and function in zebrafish
Blood, 2016Co-Authors: Megan S Rost, Ilya Shestopalov, Andy H Vo, Francesca G Barrett, David L Stachura, Jordan A ShavitAbstract:The NFE2 transcription factor is expressed in multiple hematopoietic lineages with a well-defined role in regulating megakaryocyte biogenesis and platelet production in mammals. Mice deficient in NFE2 completely lack circulating platelets, causing early lethality due to Neonatal Hemorrhage. Recent data in mice suggest some differences in embryonic and adult thrombopoiesis, and overexpression of NFE2 in murine bone marrow cells increases megakaryocyte maturation and platelet release, suggesting a role for NFE2 in both early and late megakaryocyte development. Zebrafish have emerged as an excellent model for studying hematopoiesis and thrombopoiesis due to their external development, optical transparency, high fecundity, and conservation of nearly the entire hemostatic system. Rather than platelets, zebrafish possess thrombocytes - nucleated cells believed to be the functional equivalent in mammals. We designed TALENs to target exon 4 of zebrafish nfe2 , producing two mutant strains containing either an 8 or 10 base pair deletion, both resulting in a frameshift and null allele. We tracked survival for over one year and found that unlike mammals, zebrafish survive into adulthood in the absence of Nfe2 function with no signs of overt bleeding or lethality. We bred the nfe2 mutation into a transgenic background in which thrombocytes and hematopoietic progenitor cells express green fluorescent protein (Tg( cd41 :GFP)) and are characterized by GFP high and GFP low expression, respectively. We performed flow cytometry analysis and found that the percentage of GFP high cells (circulating thrombocytes) in the peripheral blood was significantly decreased from 0.67% to 0.2% in homozygous mutants (p low cells in the kidney marrow, the site of hematopoiesis in adult zebrafish, was increased from 0.47% to 1.17% in nfe2 -/- mutants (p nfe2 null zebrafish larvae showed no significant differences from wild type siblings. Finally, we performed colony forming assays on whole kidney marrow lysates to measure the ability of hematopoietic progenitors to differentiate into thrombocytes. Both mutant and wild type adults are capable of producing thrombocytic colonies in the presence of thrombopoietin and erythropoietin. We and others have shown that thrombocytes participate in the formation of induced thrombi upon laser-mediated endothelial injury in zebrafish embryos and larvae. We tested the functionality of nfe2 -/- thrombocytes and were surprised to find that wild type and nfe2 null zebrafish larvae form fibrin- and thrombocyte-rich clots in response to endothelial injury at day of life 3 (venous circulation) and 6 (arterial circulation), respectively. Measurement of both the time to occlusion as well as the total number of thrombocytes adhering to the site of injury revealed no significant differences between wild type and nfe2 -/- larvae. These data suggest that loss of Nfe2 results in a late block in thrombopoiesis with secondary expansion of thrombocytic precursors, both features that are consistent with mammals. Surprisingly, Nfe2 appears to be dispensable for early embryonic thrombocyte production and function. These results suggest parallels with erythropoiesis, including distinct primitive and definitive pathways of development. This includes the potential for a previously unknown Nfe2-independent pathway of embryonic thrombopoiesis. The long term homozygous mutant survival will also facilitate more in depth study of Nfe2 deficiency in vivo , and further investigation could lead to alternative methodologies for the enhancement of platelet production in vivo or ex vivo . Disclosures Zon: Fate, Inc.: Equity Ownership, Membership on an entity9s Board of Directors or advisory committees, Other: Founder; Scholar Rock: Equity Ownership, Membership on an entity9s Board of Directors or advisory committees, Other: Founder; Marauder Therapeutics: Equity Ownership, Other: Founder.
Megan S Rost - One of the best experts on this subject based on the ideXlab platform.
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nfe2 is dispensable for early but required for adult thrombocyte formation and function in zebrafish
Blood Advances, 2018Co-Authors: Megan S Rost, Ilya Shestopalov, Andy H Vo, Catherine E Richter, Sylvia M Emly, Francesca G Barrett, David L Stachura, Michael Holinstat, Jordan A ShavitAbstract:The NFE2 transcription factor is expressed in multiple hematopoietic lineages with a well-defined role in regulating megakaryocyte biogenesis and platelet production in mammals. Mice deficient in NFE2 develop severe thrombocytopenia with lethality resulting from Neonatal Hemorrhage. Recent data in mammals reveal potential differences in embryonic and adult thrombopoiesis. Multiple studies in zebrafish have revealed mechanistic insights into hematopoiesis, although thrombopoiesis has been less studied. Rather than platelets, zebrafish possess thrombocytes, which are nucleated cells with similar functional properties. Using transcription activator-like effector nucleases to generate mutations in nfe2 , we show that unlike mammals, zebrafish survive to adulthood in the absence of Nfe2. Despite developing severe thrombocytopenia, homozygous mutants do not display overt Hemorrhage or reduced survival. Surprisingly, quantification of circulating thrombocytes in mutant 6-day-old larvae revealed no significant differences from wild-type siblings. Both wild-type and nfe2 null larvae formed thrombocyte-rich clots in response to endothelial injury. In addition, ex vivo thrombocytic colony formation was intact in nfe2 mutants, and adult kidney marrow displayed expansion of hematopoietic progenitors. These data suggest that loss of Nfe2 results in a late block in adult thrombopoiesis, with secondary expansion of precursors: features consistent with mammals. Overall, our data suggest parallels with erythropoiesis, including distinct primitive and definitive pathways of development and potential for a previously unknown Nfe2-independent pathway of embryonic thrombopoiesis. Long-term homozygous mutant survival will facilitate in-depth study of Nfe2 deficiency in vivo, and further investigation could lead to alternative methodologies for the enhancement of platelet production.
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nfe2 is dispensable for early but required for adult thrombocyte formation and function in zebrafish
Blood, 2016Co-Authors: Megan S Rost, Ilya Shestopalov, Andy H Vo, Francesca G Barrett, David L Stachura, Jordan A ShavitAbstract:The NFE2 transcription factor is expressed in multiple hematopoietic lineages with a well-defined role in regulating megakaryocyte biogenesis and platelet production in mammals. Mice deficient in NFE2 completely lack circulating platelets, causing early lethality due to Neonatal Hemorrhage. Recent data in mice suggest some differences in embryonic and adult thrombopoiesis, and overexpression of NFE2 in murine bone marrow cells increases megakaryocyte maturation and platelet release, suggesting a role for NFE2 in both early and late megakaryocyte development. Zebrafish have emerged as an excellent model for studying hematopoiesis and thrombopoiesis due to their external development, optical transparency, high fecundity, and conservation of nearly the entire hemostatic system. Rather than platelets, zebrafish possess thrombocytes - nucleated cells believed to be the functional equivalent in mammals. We designed TALENs to target exon 4 of zebrafish nfe2 , producing two mutant strains containing either an 8 or 10 base pair deletion, both resulting in a frameshift and null allele. We tracked survival for over one year and found that unlike mammals, zebrafish survive into adulthood in the absence of Nfe2 function with no signs of overt bleeding or lethality. We bred the nfe2 mutation into a transgenic background in which thrombocytes and hematopoietic progenitor cells express green fluorescent protein (Tg( cd41 :GFP)) and are characterized by GFP high and GFP low expression, respectively. We performed flow cytometry analysis and found that the percentage of GFP high cells (circulating thrombocytes) in the peripheral blood was significantly decreased from 0.67% to 0.2% in homozygous mutants (p low cells in the kidney marrow, the site of hematopoiesis in adult zebrafish, was increased from 0.47% to 1.17% in nfe2 -/- mutants (p nfe2 null zebrafish larvae showed no significant differences from wild type siblings. Finally, we performed colony forming assays on whole kidney marrow lysates to measure the ability of hematopoietic progenitors to differentiate into thrombocytes. Both mutant and wild type adults are capable of producing thrombocytic colonies in the presence of thrombopoietin and erythropoietin. We and others have shown that thrombocytes participate in the formation of induced thrombi upon laser-mediated endothelial injury in zebrafish embryos and larvae. We tested the functionality of nfe2 -/- thrombocytes and were surprised to find that wild type and nfe2 null zebrafish larvae form fibrin- and thrombocyte-rich clots in response to endothelial injury at day of life 3 (venous circulation) and 6 (arterial circulation), respectively. Measurement of both the time to occlusion as well as the total number of thrombocytes adhering to the site of injury revealed no significant differences between wild type and nfe2 -/- larvae. These data suggest that loss of Nfe2 results in a late block in thrombopoiesis with secondary expansion of thrombocytic precursors, both features that are consistent with mammals. Surprisingly, Nfe2 appears to be dispensable for early embryonic thrombocyte production and function. These results suggest parallels with erythropoiesis, including distinct primitive and definitive pathways of development. This includes the potential for a previously unknown Nfe2-independent pathway of embryonic thrombopoiesis. The long term homozygous mutant survival will also facilitate more in depth study of Nfe2 deficiency in vivo , and further investigation could lead to alternative methodologies for the enhancement of platelet production in vivo or ex vivo . Disclosures Zon: Fate, Inc.: Equity Ownership, Membership on an entity9s Board of Directors or advisory committees, Other: Founder; Scholar Rock: Equity Ownership, Membership on an entity9s Board of Directors or advisory committees, Other: Founder; Marauder Therapeutics: Equity Ownership, Other: Founder.
Evan J Sadler - One of the best experts on this subject based on the ideXlab platform.
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incomplete embryonic lethality and fatal Neonatal Hemorrhage caused by prothrombin deficiency in mice
Proceedings of the National Academy of Sciences of the United States of America, 1998Co-Authors: Jiachun Xue, Lisa A Westfield, Elodee A Tuley, Qing Zhang, Kyuhwan Shim, Xinglong Zheng, Evan J SadlerAbstract:Deficiency of blood coagulation factor V or tissue factor causes the death of mouse embryos by 10.5 days of gestation, suggesting that part of the blood coagulation system is necessary for development. This function is proposed to require either generation of the serine protease thrombin and cell signaling through protease-activated receptors or an activity of tissue factor that is distinct from blood clotting. We find that murine deficiency of prothrombin clotting factor 2 (Cf2) was associated with the death of approximately 50% of Cf2−/− embryos by embryonic day 10.5 (E10.5), and surviving embryos had characteristic defects in yolk sac vasculature. Most of the remaining Cf2−/− embryos died by E15.5, but those surviving to E18.5 appeared normal. The rare Cf2−/− neonates died of Hemorrhage on the first postnatal day. These studies suggest that a part of the blood coagulation system is adapted to perform a developmental function. Other mouse models show that the absence of platelets or of fibrinogen does not cause fetal wastage. Therefore, the role of thrombin in development may be independent of its effects on blood coagulation and instead may involve signal transduction on cells other than platelets.
Andy H Vo - One of the best experts on this subject based on the ideXlab platform.
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nfe2 is dispensable for early but required for adult thrombocyte formation and function in zebrafish
Blood Advances, 2018Co-Authors: Megan S Rost, Ilya Shestopalov, Andy H Vo, Catherine E Richter, Sylvia M Emly, Francesca G Barrett, David L Stachura, Michael Holinstat, Jordan A ShavitAbstract:The NFE2 transcription factor is expressed in multiple hematopoietic lineages with a well-defined role in regulating megakaryocyte biogenesis and platelet production in mammals. Mice deficient in NFE2 develop severe thrombocytopenia with lethality resulting from Neonatal Hemorrhage. Recent data in mammals reveal potential differences in embryonic and adult thrombopoiesis. Multiple studies in zebrafish have revealed mechanistic insights into hematopoiesis, although thrombopoiesis has been less studied. Rather than platelets, zebrafish possess thrombocytes, which are nucleated cells with similar functional properties. Using transcription activator-like effector nucleases to generate mutations in nfe2 , we show that unlike mammals, zebrafish survive to adulthood in the absence of Nfe2. Despite developing severe thrombocytopenia, homozygous mutants do not display overt Hemorrhage or reduced survival. Surprisingly, quantification of circulating thrombocytes in mutant 6-day-old larvae revealed no significant differences from wild-type siblings. Both wild-type and nfe2 null larvae formed thrombocyte-rich clots in response to endothelial injury. In addition, ex vivo thrombocytic colony formation was intact in nfe2 mutants, and adult kidney marrow displayed expansion of hematopoietic progenitors. These data suggest that loss of Nfe2 results in a late block in adult thrombopoiesis, with secondary expansion of precursors: features consistent with mammals. Overall, our data suggest parallels with erythropoiesis, including distinct primitive and definitive pathways of development and potential for a previously unknown Nfe2-independent pathway of embryonic thrombopoiesis. Long-term homozygous mutant survival will facilitate in-depth study of Nfe2 deficiency in vivo, and further investigation could lead to alternative methodologies for the enhancement of platelet production.
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nfe2 is dispensable for early but required for adult thrombocyte formation and function in zebrafish
Blood, 2016Co-Authors: Megan S Rost, Ilya Shestopalov, Andy H Vo, Francesca G Barrett, David L Stachura, Jordan A ShavitAbstract:The NFE2 transcription factor is expressed in multiple hematopoietic lineages with a well-defined role in regulating megakaryocyte biogenesis and platelet production in mammals. Mice deficient in NFE2 completely lack circulating platelets, causing early lethality due to Neonatal Hemorrhage. Recent data in mice suggest some differences in embryonic and adult thrombopoiesis, and overexpression of NFE2 in murine bone marrow cells increases megakaryocyte maturation and platelet release, suggesting a role for NFE2 in both early and late megakaryocyte development. Zebrafish have emerged as an excellent model for studying hematopoiesis and thrombopoiesis due to their external development, optical transparency, high fecundity, and conservation of nearly the entire hemostatic system. Rather than platelets, zebrafish possess thrombocytes - nucleated cells believed to be the functional equivalent in mammals. We designed TALENs to target exon 4 of zebrafish nfe2 , producing two mutant strains containing either an 8 or 10 base pair deletion, both resulting in a frameshift and null allele. We tracked survival for over one year and found that unlike mammals, zebrafish survive into adulthood in the absence of Nfe2 function with no signs of overt bleeding or lethality. We bred the nfe2 mutation into a transgenic background in which thrombocytes and hematopoietic progenitor cells express green fluorescent protein (Tg( cd41 :GFP)) and are characterized by GFP high and GFP low expression, respectively. We performed flow cytometry analysis and found that the percentage of GFP high cells (circulating thrombocytes) in the peripheral blood was significantly decreased from 0.67% to 0.2% in homozygous mutants (p low cells in the kidney marrow, the site of hematopoiesis in adult zebrafish, was increased from 0.47% to 1.17% in nfe2 -/- mutants (p nfe2 null zebrafish larvae showed no significant differences from wild type siblings. Finally, we performed colony forming assays on whole kidney marrow lysates to measure the ability of hematopoietic progenitors to differentiate into thrombocytes. Both mutant and wild type adults are capable of producing thrombocytic colonies in the presence of thrombopoietin and erythropoietin. We and others have shown that thrombocytes participate in the formation of induced thrombi upon laser-mediated endothelial injury in zebrafish embryos and larvae. We tested the functionality of nfe2 -/- thrombocytes and were surprised to find that wild type and nfe2 null zebrafish larvae form fibrin- and thrombocyte-rich clots in response to endothelial injury at day of life 3 (venous circulation) and 6 (arterial circulation), respectively. Measurement of both the time to occlusion as well as the total number of thrombocytes adhering to the site of injury revealed no significant differences between wild type and nfe2 -/- larvae. These data suggest that loss of Nfe2 results in a late block in thrombopoiesis with secondary expansion of thrombocytic precursors, both features that are consistent with mammals. Surprisingly, Nfe2 appears to be dispensable for early embryonic thrombocyte production and function. These results suggest parallels with erythropoiesis, including distinct primitive and definitive pathways of development. This includes the potential for a previously unknown Nfe2-independent pathway of embryonic thrombopoiesis. The long term homozygous mutant survival will also facilitate more in depth study of Nfe2 deficiency in vivo , and further investigation could lead to alternative methodologies for the enhancement of platelet production in vivo or ex vivo . Disclosures Zon: Fate, Inc.: Equity Ownership, Membership on an entity9s Board of Directors or advisory committees, Other: Founder; Scholar Rock: Equity Ownership, Membership on an entity9s Board of Directors or advisory committees, Other: Founder; Marauder Therapeutics: Equity Ownership, Other: Founder.
Ilya Shestopalov - One of the best experts on this subject based on the ideXlab platform.
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nfe2 is dispensable for early but required for adult thrombocyte formation and function in zebrafish
Blood Advances, 2018Co-Authors: Megan S Rost, Ilya Shestopalov, Andy H Vo, Catherine E Richter, Sylvia M Emly, Francesca G Barrett, David L Stachura, Michael Holinstat, Jordan A ShavitAbstract:The NFE2 transcription factor is expressed in multiple hematopoietic lineages with a well-defined role in regulating megakaryocyte biogenesis and platelet production in mammals. Mice deficient in NFE2 develop severe thrombocytopenia with lethality resulting from Neonatal Hemorrhage. Recent data in mammals reveal potential differences in embryonic and adult thrombopoiesis. Multiple studies in zebrafish have revealed mechanistic insights into hematopoiesis, although thrombopoiesis has been less studied. Rather than platelets, zebrafish possess thrombocytes, which are nucleated cells with similar functional properties. Using transcription activator-like effector nucleases to generate mutations in nfe2 , we show that unlike mammals, zebrafish survive to adulthood in the absence of Nfe2. Despite developing severe thrombocytopenia, homozygous mutants do not display overt Hemorrhage or reduced survival. Surprisingly, quantification of circulating thrombocytes in mutant 6-day-old larvae revealed no significant differences from wild-type siblings. Both wild-type and nfe2 null larvae formed thrombocyte-rich clots in response to endothelial injury. In addition, ex vivo thrombocytic colony formation was intact in nfe2 mutants, and adult kidney marrow displayed expansion of hematopoietic progenitors. These data suggest that loss of Nfe2 results in a late block in adult thrombopoiesis, with secondary expansion of precursors: features consistent with mammals. Overall, our data suggest parallels with erythropoiesis, including distinct primitive and definitive pathways of development and potential for a previously unknown Nfe2-independent pathway of embryonic thrombopoiesis. Long-term homozygous mutant survival will facilitate in-depth study of Nfe2 deficiency in vivo, and further investigation could lead to alternative methodologies for the enhancement of platelet production.
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nfe2 is dispensable for early but required for adult thrombocyte formation and function in zebrafish
Blood, 2016Co-Authors: Megan S Rost, Ilya Shestopalov, Andy H Vo, Francesca G Barrett, David L Stachura, Jordan A ShavitAbstract:The NFE2 transcription factor is expressed in multiple hematopoietic lineages with a well-defined role in regulating megakaryocyte biogenesis and platelet production in mammals. Mice deficient in NFE2 completely lack circulating platelets, causing early lethality due to Neonatal Hemorrhage. Recent data in mice suggest some differences in embryonic and adult thrombopoiesis, and overexpression of NFE2 in murine bone marrow cells increases megakaryocyte maturation and platelet release, suggesting a role for NFE2 in both early and late megakaryocyte development. Zebrafish have emerged as an excellent model for studying hematopoiesis and thrombopoiesis due to their external development, optical transparency, high fecundity, and conservation of nearly the entire hemostatic system. Rather than platelets, zebrafish possess thrombocytes - nucleated cells believed to be the functional equivalent in mammals. We designed TALENs to target exon 4 of zebrafish nfe2 , producing two mutant strains containing either an 8 or 10 base pair deletion, both resulting in a frameshift and null allele. We tracked survival for over one year and found that unlike mammals, zebrafish survive into adulthood in the absence of Nfe2 function with no signs of overt bleeding or lethality. We bred the nfe2 mutation into a transgenic background in which thrombocytes and hematopoietic progenitor cells express green fluorescent protein (Tg( cd41 :GFP)) and are characterized by GFP high and GFP low expression, respectively. We performed flow cytometry analysis and found that the percentage of GFP high cells (circulating thrombocytes) in the peripheral blood was significantly decreased from 0.67% to 0.2% in homozygous mutants (p low cells in the kidney marrow, the site of hematopoiesis in adult zebrafish, was increased from 0.47% to 1.17% in nfe2 -/- mutants (p nfe2 null zebrafish larvae showed no significant differences from wild type siblings. Finally, we performed colony forming assays on whole kidney marrow lysates to measure the ability of hematopoietic progenitors to differentiate into thrombocytes. Both mutant and wild type adults are capable of producing thrombocytic colonies in the presence of thrombopoietin and erythropoietin. We and others have shown that thrombocytes participate in the formation of induced thrombi upon laser-mediated endothelial injury in zebrafish embryos and larvae. We tested the functionality of nfe2 -/- thrombocytes and were surprised to find that wild type and nfe2 null zebrafish larvae form fibrin- and thrombocyte-rich clots in response to endothelial injury at day of life 3 (venous circulation) and 6 (arterial circulation), respectively. Measurement of both the time to occlusion as well as the total number of thrombocytes adhering to the site of injury revealed no significant differences between wild type and nfe2 -/- larvae. These data suggest that loss of Nfe2 results in a late block in thrombopoiesis with secondary expansion of thrombocytic precursors, both features that are consistent with mammals. Surprisingly, Nfe2 appears to be dispensable for early embryonic thrombocyte production and function. These results suggest parallels with erythropoiesis, including distinct primitive and definitive pathways of development. This includes the potential for a previously unknown Nfe2-independent pathway of embryonic thrombopoiesis. The long term homozygous mutant survival will also facilitate more in depth study of Nfe2 deficiency in vivo , and further investigation could lead to alternative methodologies for the enhancement of platelet production in vivo or ex vivo . Disclosures Zon: Fate, Inc.: Equity Ownership, Membership on an entity9s Board of Directors or advisory committees, Other: Founder; Scholar Rock: Equity Ownership, Membership on an entity9s Board of Directors or advisory committees, Other: Founder; Marauder Therapeutics: Equity Ownership, Other: Founder.
