Related Experiment Video

Updated: Aug 26, 2026

Assessment of Mitochondrial Fission/Fusion Dynamics in Kidney Proximal Tubular Cells
06:14

Assessment of Mitochondrial Fission/Fusion Dynamics in Kidney Proximal Tubular Cells

Published on: November 14, 2025

Levels of human Fis1 at the mitochondrial outer membrane regulate mitochondrial morphology

Diana Stojanovski1, Olga S Koutsopoulos, Koji Okamoto

  • 1Department of Biochemistry, La Trobe University, 3086 Melbourne, Australia.

Journal of Cell Science
|March 5, 2004
PubMed

Insights

Human Fis1 (hFis1) is crucial for mitochondrial fission. Its levels impact mitochondrial morphology, and it influences the recruitment of key proteins involved in mitochondrial dynamics.

Area of Science:

  • Cell Biology
  • Mitochondrial Biology
  • Molecular Biology

Background:

  • Mitochondria require balanced fission and fusion for proper cellular function.
  • In yeast, Fis1p, Dnm1p, and Mdv1p coordinate mitochondrial outer membrane fission.
  • Mammalian mitochondrial fission involves Drp1, but other components remain uncharacterized.

Purpose of the Study:

  • To characterize the human homolog of yeast Fis1, termed hFis1.
  • To investigate the role of hFis1 in mammalian mitochondrial fission and morphology.

Main Methods:

  • Characterization of hFis1 targeting and insertion into the mitochondrial outer membrane.
  • Assessing hFis1 function in yeast complementation studies.
  • Inducing mitochondrial fragmentation via hFis1 overexpression in tissue culture cells.
  • Utilizing RNA interference (RNAi) to knockdown hFis1 in COS-7 cells.

Main Results:

  • hFis1 targets the mitochondrial outer membrane via its C-terminal transmembrane domain.
  • hFis1 overexpression causes mitochondrial fragmentation and aggregation, suppressible by dominant-negative Drp1.
  • hFis1 knockdown leads to mitochondrial elongation and morphological defects.
  • hFis1 function is not conserved in yeast Fis1p complementation.

Conclusions:

  • hFis1 plays a significant role in regulating mitochondrial fission in mammalian cells.
  • The levels of hFis1 at the mitochondrial outer membrane are critical for maintaining mitochondrial morphology.
  • hFis1 influences mitochondrial dynamics by affecting fission events.

More Related Videos

Using Live Cell STED Imaging to Visualize Mitochondrial Inner Membrane Ultrastructure in Neuronal Cell Models08:48

Using Live Cell STED Imaging to Visualize Mitochondrial Inner Membrane Ultrastructure in Neuronal Cell Models

Published on: June 30, 2023

Understanding the Changes in Mitochondrial Morphology through Dynamic and Three-dimensional Fluorescence Micrographs08:15

Understanding the Changes in Mitochondrial Morphology through Dynamic and Three-dimensional Fluorescence Micrographs

Published on: August 15, 2025

Related Concept Videos

Mitochondrial Membranes01:45

Mitochondrial 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,...
Mitochondrial Membranes01:45

Mitochondrial 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,...
The Inner Mitochondrial Membrane01:28

The Inner Mitochondrial Membrane

The inner mitochondrial membrane is the primary site of ATP synthesis. The inner membrane domain that forms a smooth layer adjacent to the outer membrane is called the inner boundary membrane. This domain contains membrane transporters that drive metabolites in and out of the mitochondria.  In contrast, the inner membrane network that invaginates into the matrix space is called the cristae membrane. This domain accounts for principle mitochondrial function as it accommodates the protein...
Porin Insertion in the Outer Mitochondrial Membrane01:12

Porin Insertion in the Outer Mitochondrial Membrane

Porins are beta-barrel proteins translocated to the mitochondrial outer membrane through the TOM complex into the intermembrane space. Porin precursors bind TIM chaperones within the intermembrane space and are guided to the Sorting and Assembly Machinery complex or SAM complex on the outer mitochondrial membrane.
Three models describe the assembly of porins by the SAM complex and their insertion into the outer membrane. Model 1 suggests that porins are assembled outside the SAM channel as the...
Structure of Porins01:21

Structure of Porins

Mitochondria, chloroplasts, and gram-negative bacteria have transmembrane, beta-barrel proteins called porins to mediate the free diffusion of ions and metabolites across the membrane. Mitochondrial porin precursors contain conserved amino acid sequences called beta signals at their C-terminal. Beta signals have a  motif of PoXGXXHyXHy (Po-Polar, X-Any amino acid, G-Glycine, Hy-LargeHydrophobic), which are crucial for precursor recognition to initiate precursor assembly. Beta-barrel precursors...
Mitochondrial Protein Sorting01:39

Mitochondrial Protein Sorting

Mitochondria are double-membrane organelles of the eukaryotes involved in cellular metabolism, signaling, ATP synthesis, and programmed cell death.  Each of these processes requires specific proteins and enzymes that must be correctly sorted to the right mitochondrial subcompartment for the proper functioning of the organelle.
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...