SUMMARY:
Dynamin 2-mediated interactions between actin and membranes are critical for actin bundle formation in HPCs.
TITLE:
The Lipid-Binding Defective Dynamin 2 Mutant in Charcot-Marie-Tooth Disease Impairs Proper Actin Bundling and Actin Organization in Glomerular Podocytes
DESCRIPTION:
Dynamin is an endocytic protein that functions in vesicle formation by scission of invaginated membranes. Dynamin maintains the structure of foot processes in glomerular podocytes by directly and indirectly interacting with actin filaments. However, molecular mechanisms underlying dynamin-mediated actin regulation are largely unknown. Here, biochemical and cell biological experiments were conducted to uncover how dynamin modulates interactions between membranes and actin in human podocytes….
CONTENT:
Front Cell Dev Biol. 2022 May 10;10:884509. doi: 10.3389/fcell.2022.884509. eCollection 2022.
ABSTRACT
Dynamin is an endocytic protein that functions in vesicle formation by scission of invaginated membranes. Dynamin maintains the structure of foot processes in glomerular podocytes by directly and indirectly interacting with actin filaments. However, molecular mechanisms underlying dynamin-mediated actin regulation are largely unknown. Here, biochemical and cell biological experiments were conducted to uncover how dynamin modulates interactions between membranes and actin in human podocytes. Actin-bundling, membrane tubulating, and GTPase activities of dynamin were examined in vitro using recombinant dynamin 2-wild-type (WT) or dynamin 2-K562E, which is a mutant found in Charcot-Marie-Tooth patients. Dynamin 2-WT and dynamin 2-K562E led to the formation of prominent actin bundles with constant diameters. Whereas liposomes incubated with dynamin 2-WT resulted in tubule formation, dynamin 2-K562E reduced tubulation. Actin filaments and liposomes stimulated dynamin 2-WT GTPase activity by 6- and 20-fold, respectively. Actin-filaments, but not liposomes, stimulated dynamin 2-K562E GTPase activity by 4-fold. Self-assembly-dependent GTPase activity of dynamin 2-K562E was reduced to one-third compared to that of dynamin 2-WT. Incubation of liposomes and actin with dynamin 2-WT led to the formation of thick actin bundles, which often bound to liposomes. The interaction between lipid membranes and actin bundles by dynamin 2-K562E was lower than that by dynamin 2-WT. Dynamin 2-WT partially colocalized with stress fibers and actin bundles based on double immunofluorescence of human podocytes. Dynamin 2-K562E expression resulted in decreased stress fiber density and the formation of aberrant actin clusters. Dynamin 2-K562E colocalized with α-actinin-4 in aberrant actin clusters. Reformation of stress fibers after cytochalasin D-induced actin depolymerization and washout was less effective in dynamin 2-K562E-expressing cells than that in dynamin 2-WT. Bis-T-23, a dynamin self-assembly enhancer, was unable to rescue the decreased focal adhesion numbers and reduced stress fiber density induced by dynamin 2-K562E expression. These results suggest that the low affinity of the K562E mutant for lipid membranes, and atypical self-assembling properties, lead to actin disorganization in HPCs. Moreover, lipid-binding and self-assembly of dynamin 2 along actin filaments are required for podocyte morphology and functions. Finally, dynamin 2-mediated interactions between actin and membranes are critical for actin bundle formation in HPCs.
PMID:35620056 | PMC:PMC9127447 | DOI:10.3389/fcell.2022.884509
SOURCE:
Frontiers in cell and developmental biology
TAGS:
Dynamin 2
CATEGORY:
Research
SUBCATEGORY:
n/a
DATE – PUBLISHED:
2022-05-10T08:53:31Z
DATE – DOI: 2022-05-10T08:53:31Z
DATE – PUBMED: 2022 May 10
DATE OUTPUT MATCHED: True
DATE – ADDED:
Fri, 27 May 2022 06:00:00 -0400
DATE – RETRIEVED:
05/27/22 07:17AM
2022-05-27T07:17:46-04:00
FEATURED IMAGE:
Media Uploaded (image/png)
IDENTIFIER:
pmid:35620056,pmc:PMC9127447,doi:10.3389/fcell.2022.884509
PUBMED ID:
pubmed:35620056
DOI:
10.3389/fcell.2022.884509
LINK – PUBMED:
https://pubmed.ncbi.nlm.nih.gov/35620056/
LINK – DOI:
https://doi.org/10.3389/fcell.2022.884509
LINK – PUBLISHER:
https://www.frontiersin.org/articles/10.3389/fcell.2022.884509/full
REFERENCES:
CMT Treatment Report, Urgent Research, 2022-05-27T07:17:46-04:00, https://www.cmttreatmentreport.com.
