Related Experiment Video
Updated: May 16, 2026
08:15
Understanding the Changes in Mitochondrial Morphology through Dynamic and Three-dimensional Fluorescence Micrographs
Published on: August 15, 2025
PI(3)P regulates mitochondrial dynamics through EXC-5-dependent actin remodeling
Sneha Hegde1,2, Marc Germain1,2
1Groupe de Recherche en Signalisation Cellulaire and Département de Biologie Médicale, Université du Québec à Trois-Rivières, Trois-Rivières, Canada.
The Journal of Cell Biology
|May 14, 2026
Summary
Mitochondrial dynamics are crucial for cell function but poorly understood. New research reveals how endosomal phosphoinositide 3-phosphate (PI(3)P) signals CDC42 to regulate actin polymerization on mitochondria.
Area of Science:
- Cell Biology
- Mitochondrial Biology
- Biochemistry
Background:
- Mitochondrial dynamics are essential for cellular function, involving complex regulatory pathways.
- The precise coordination and upstream signals governing mitochondrial dynamics remain incompletely understood.
Purpose of the Study:
- To elucidate the upstream signaling mechanisms that regulate mitochondrial dynamics.
- To investigate the role of endosomal phosphoinositides in mitochondrial regulation.
Main Methods:
- Investigated the role of phosphoinositide 3-phosphate (PI(3)P) in mitochondrial dynamics.
- Utilized cell-based assays to examine CDC42 activity and actin polymerization on mitochondria.
Main Results:
- Demonstrated that endosomal PI(3)P promotes CDC42-dependent actin polymerization on mitochondria.
- Identified a novel link between endosomal signaling and mitochondrial cytoskeletal regulation.
Conclusions:
- Endosomal PI(3)P acts as a key upstream signal coordinating mitochondrial dynamics.
- This finding provides new insights into the regulation of mitochondrial morphology and function.
Related Concept Videos
01:45Mitochondrial Membranes
A single mitochondrion is a bean-shaped organelle enclosed by a double-membrane system. The outer membrane of mitochondria is smooth and contains many porins - the integral membrane transporters. Porins enable free diffusion of ions and small uncharged molecules through the outer mitochondrial membrane but limit the transport of molecules larger than 5000 Daltons. Further, the outer mitochondrial membrane forms a unique structure called membrane contact sites with other subcellular organelles,...
01:37Energy to Drive Translocation
Mitochondrial protein import is powered by two distinct energy sources: ATP hydrolysis and electrochemical potential across the inner membrane. Newly synthesized precursors are bound by cytosolic chaperones of the Hsp70 family, which guide them to the import receptors on the mitochondrial surface. Utilizing the energy of ATP hydrolysis, Hsp70 chaperones transfer these precursors to the TOM receptors on the mitochondrial outer membrane.
Generally, polypeptides are unfolded by two distinct...
Generally, polypeptides are unfolded by two distinct...
01:14Generation of Straight or Branched Actin Filaments
The straight or branched structure formation of actin filaments is controlled by nucleating proteins such as the formins and Arp2/3 complex. Formin-mediated assembly results in straight filaments, whereas Arp2/3 protein complex-mediated assembly results in branched actin filaments.
Arp2/3 Complex
Arp2/3 complex is a seven-subunit complex consisting of two proteins similar to actin- Arp2 and Arp3, and five other subunits that help keep Arp2 and Arp3 inactive. When required, the complex is...
Arp2/3 Complex
Arp2/3 complex is a seven-subunit complex consisting of two proteins similar to actin- Arp2 and Arp3, and five other subunits that help keep Arp2 and Arp3 inactive. When required, the complex is...
01:19Actin Filament Depolymerization
Actin filaments (F-actin) are composed of actin subunits. The dissociation of actin monomers can occur from either end of F-actin. The rate of dissociation is faster from the minus-end or the pointed end, where the actin subunits exist with a bound ADP, together known as ADP-actin. The depolymerization of F-actin is aided by proteins, including the actin-depolymerizing factor (ADF) and cofilin family of proteins, gelsolin, and glia maturation factor (GMF).
In F-actin, the ADF/cofilin proteins...
In F-actin, the ADF/cofilin proteins...
01:19Translocation of Proteins into the Mitochondria
Mitochondrial precursors are translocated to the internal subcompartments via independent mechanisms involving distinct protein machineries called translocases.
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
01:42Phosphoinositides and PIPs
Phosphoinositides are a group of phospholipids containing a glycerol backbone with two fatty acid chains and a phosphate attached to a myoinositol sugar ring. The inositol head group extends into the cytoplasm, where it is modified by adding phosphate groups to form phosphatidylinositol phosphates or PIPs.
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...