{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/92945"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/92945","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"A biochemical investigation of actin disassembly mechanisms","abstract":"The dynamic nature of the actin cytoskeleton enables the rapid shape changes that are necessary for processes such as wound healing, motility and division of cells. Disassembly of actin filaments is extremely critical for the reorganization of cell shape. The cell possesses several factors that depolymerize actin filaments in an environment that has a high concentration of polymerizable monomer. However current microscopic techniques preclude the direct observation of the dynamics of individual actin filaments that usually exist as part of highly crosslinked networks inside cells. Therefore, the mechanism(s) by which actin filaments disassemble inside cells remains unclear. In this work we use a combination of single filament imaging of fluorescently labeled actin filaments as well as pyrene and FRET-based spectroscopy in order to reconstitute cellular disassembly in vitro in the presence of three factors: cofilin, coronin and Aip1. These three factors have been shown to be principally responsible for the disassembly activity of thymus extract. We describe here our discoveries regarding catastrophic whole filament destabilization of actin in the presence of the three factors. We also reinvestigated the role of Aip1 alone in cofilin-mediated depolymerization of actin filaments. We showed that Aip1 is not an actin capping protein as was previously thought, however it can destabilize cofilin-saturated stable filaments and potentiate cofilin’s severing and depolymerization activity. During the course of our work we also uncovered some insights on the biophysics of filament severing in the presence of cofilin.","abstract_html":"The dynamic nature of the actin cytoskeleton enables the rapid shape changes that are necessary for processes such as wound healing, motility and division of cells. Disassembly of actin filaments is extremely critical for the reorganization of cell shape. The cell possesses several factors that depolymerize actin filaments in an environment that has a high concentration of polymerizable monomer. However current microscopic techniques preclude the direct observation of the dynamics of individual actin filaments that usually exist as part of highly crosslinked networks inside cells. Therefore, the mechanism(s) by which actin filaments disassemble inside cells remains unclear. In this work we use a combination of single filament imaging of fluorescently labeled actin filaments as well as pyrene and FRET-based spectroscopy in order to reconstitute cellular disassembly in vitro in the presence of three factors: cofilin, coronin and Aip1. These three factors have been shown to be principally responsible for the disassembly activity of thymus extract. We describe here our discoveries regarding catastrophic whole filament destabilization of actin in the presence of the three factors. We also reinvestigated the role of Aip1 alone in cofilin-mediated depolymerization of actin filaments. We showed that Aip1 is not an actin capping protein as was previously thought, however it can destabilize cofilin-saturated stable filaments and potentiate cofilin’s severing and depolymerization activity. During the course of our work we also uncovered some insights on the biophysics of filament severing in the presence of cofilin.","abstract_has_math":false,"creators":["Nadkarni, Ambika Vithal"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Cell and Developmental Biology","degree_department":null,"school":null,"contributors":["Brieher, William M.","Newmark, Phillip A.","Gillette, Martha U.","Raetzman, Lori T."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2016,"date_issued":"2016-11-10T18:27:48Z","date_published":"2016-11-10T18:27:48Z","updated_at":"2026-07-22T22:26:35Z","subjects":["Actin depolymerization","cofilin","Aip1"],"languages":["en"],"rights":["Copyright 2016 Ambika Nadkarni"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/92945","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Brieher, William M.","Newmark, Phillip A.","Gillette, Martha U.","Raetzman, Lori T."]},{"key":"dc:creator","label":"Author","values":["Nadkarni, Ambika Vithal"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2016-11-10T18:27:48Z","2018-11-11T10:15:11Z","2016-07-13","2016-08"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Cell and Developmental Biology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Actin depolymerization","cofilin","Aip1"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2016 Ambika Nadkarni"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/92945"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The dynamic nature of the actin cytoskeleton enables the rapid shape changes that are necessary for processes such as wound healing, motility and division of cells. Disassembly of actin filaments is extremely critical for the reorganization of cell shape. The cell possesses several factors that depolymerize actin filaments in an environment that has a high concentration of polymerizable monomer. However current microscopic techniques preclude the direct observation of the dynamics of individual actin filaments that usually exist as part of highly crosslinked networks inside cells. Therefore, the mechanism(s) by which actin filaments disassemble inside cells remains unclear. In this work we use a combination of single filament imaging of fluorescently labeled actin filaments as well as pyrene and FRET-based spectroscopy in order to reconstitute cellular disassembly in vitro in the presence of three factors: cofilin, coronin and Aip1. These three factors have been shown to be principally responsible for the disassembly activity of thymus extract. We describe here our discoveries regarding catastrophic whole filament destabilization of actin in the presence of the three factors. We also reinvestigated the role of Aip1 alone in cofilin-mediated depolymerization of actin filaments. We showed that Aip1 is not an actin capping protein as was previously thought, however it can destabilize cofilin-saturated stable filaments and potentiate cofilin’s severing and depolymerization activity. During the course of our work we also uncovered some insights on the biophysics of filament severing in the presence of cofilin.","Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2018-08-01","The student, Ambika Nadkarni, accepted the attached license on 2016-07-12 at 15:34.","The student, Ambika Nadkarni, submitted this Dissertation for approval on 2016-07-12 at 15:43.","This Dissertation was approved for publication on 2016-07-13 at 16:45.","DSpace SAF Submission Ingestion Package generated from Vireo submission #9895 on 2016-11-10 at 12:20:33","Made available in DSpace on 2016-11-10T18:27:48Z (GMT). No. of bitstreams: 2 NADKARNI-DISSERTATION-2016.pdf: 1673184 bytes, checksum: 085b3fe695803875694e5ecf3b3ea77f (MD5) LICENSE.txt: 4212 bytes, checksum: 819ec08764a28f5758e53902146e0396 (MD5) Previous issue date: 2016-07-13","Embargo set by: Seth Robbins for item 95365 Lift date: 2018-11-10T18:28:02Z Reason: Author requested closed access (OA after 2yrs) in Vireo ETD system","Limited Restriction Lifted for Item 95365 on 2018-11-11T10:15:11Z."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["A biochemical investigation of actin disassembly mechanisms"]}]}],"canonical_facts":{"dc:contributor":["Brieher, William M.","Newmark, Phillip A.","Gillette, Martha U.","Raetzman, Lori T."],"dc:creator":["Nadkarni, Ambika Vithal"],"dc:date":["2016-11-10T18:27:48Z","2018-11-11T10:15:11Z","2016-07-13","2016-08"],"dc:description":["The dynamic nature of the actin cytoskeleton enables the rapid shape changes that are necessary for processes such as wound healing, motility and division of cells. Disassembly of actin filaments is extremely critical for the reorganization of cell shape. The cell possesses several factors that depolymerize actin filaments in an environment that has a high concentration of polymerizable monomer. However current microscopic techniques preclude the direct observation of the dynamics of individual actin filaments that usually exist as part of highly crosslinked networks inside cells. Therefore, the mechanism(s) by which actin filaments disassemble inside cells remains unclear. In this work we use a combination of single filament imaging of fluorescently labeled actin filaments as well as pyrene and FRET-based spectroscopy in order to reconstitute cellular disassembly in vitro in the presence of three factors: cofilin, coronin and Aip1. These three factors have been shown to be principally responsible for the disassembly activity of thymus extract. We describe here our discoveries regarding catastrophic whole filament destabilization of actin in the presence of the three factors. We also reinvestigated the role of Aip1 alone in cofilin-mediated depolymerization of actin filaments. We showed that Aip1 is not an actin capping protein as was previously thought, however it can destabilize cofilin-saturated stable filaments and potentiate cofilin’s severing and depolymerization activity. During the course of our work we also uncovered some insights on the biophysics of filament severing in the presence of cofilin.","Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2018-08-01","The student, Ambika Nadkarni, accepted the attached license on 2016-07-12 at 15:34.","The student, Ambika Nadkarni, submitted this Dissertation for approval on 2016-07-12 at 15:43.","This Dissertation was approved for publication on 2016-07-13 at 16:45.","DSpace SAF Submission Ingestion Package generated from Vireo submission #9895 on 2016-11-10 at 12:20:33","Made available in DSpace on 2016-11-10T18:27:48Z (GMT). No. of bitstreams: 2 NADKARNI-DISSERTATION-2016.pdf: 1673184 bytes, checksum: 085b3fe695803875694e5ecf3b3ea77f (MD5) LICENSE.txt: 4212 bytes, checksum: 819ec08764a28f5758e53902146e0396 (MD5) Previous issue date: 2016-07-13","Embargo set by: Seth Robbins for item 95365 Lift date: 2018-11-10T18:28:02Z Reason: Author requested closed access (OA after 2yrs) in Vireo ETD system","Limited Restriction Lifted for Item 95365 on 2018-11-11T10:15:11Z."],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/2142/92945"],"dc:language":["en"],"dc:rights":["Copyright 2016 Ambika Nadkarni"],"dc:subject":["Actin depolymerization","cofilin","Aip1"],"dc:title":["A biochemical investigation of actin disassembly mechanisms"],"dc:type":["text"],"thesis:degree_discipline":["Cell and Developmental Biology"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:26:35Z"}