Close

An oncogenic isoform of septin 9 promotes the formation of juxtanuclear invadopodia by reducing nuclear deformability

Joshua Okletey, Dimitrios Angelis, Tia M. Jones, Cristina Montagna, Elias T. Spiliotis

Preprint posted on 18 June 2023 https://www.biorxiv.org/content/10.1101/2023.06.18.545473v1

Article now published in Cell Reports at https://www.cell.com/cell-reports/fulltext/S2211-1247(23)00904-X

A bodyguard to get away: Sept9_i1 influences nuclear rigidity to escape the tissue by invadopodia.

Selected by Megane Rayer

Background.

One of the big challenges for cancer cells is to escape the original tumor to invade a new tissue. The formation of invadopodia allows cancer cells to leave the original tumor [1]. This process involves mostly F-actin core – composed of TKS5 [2] and MT1-MMP [3] which is responsible  for matrix degradation. Interestingly, the invadopodia begin mostly under the nucleus from where they can deformed it, suggesting that the actin core is physically linked to the nucleus [4].

Another challenge for the cancer cells is to go through the extracellular matrix (ECM) with a massive and rigid organelle like the nucleus. Cells must “find” ways to passing the ECM without damaging the nucleus too much. There are several possibilities. One is to make the nuclear envelope softer and another one is matrix degradation. However, these mechanisms remain little understood during invadopodia formation.

Septin, a GTP-binding protein interacting with the cytoskeleton [5, 6], could also be involved in invadopodia formation because it has been shown that Spet9-i1 overexpression enhances cancer cells invasion and metastasis [7].

The question now is:

Is there a link between the nucleus and septins during invadopodia formation?

The preprint “An oncogenic isoform of septin 9 promotes the formation of juxtanuclear invadopodia by reducing nuclear deformability” proposes a mechanism in which Sept9_i1 protects the nucleus against deformability during the early steps of cell invasion. To conduct this study, the authors used breast cancer cells containing a high copy number of sept9_i1 in 2D and 3D ECM assay.  The 3D assay involved plating cells on permeable Matrigel and a laminin-coated Transwell membrane. They used EGF to stimulate invadopodia formation.

 

Key findings.

  • Sept9_i1 dynamics in invadopodia.

Sept9_i1 is specifically required for invadopodia formation because its inhibition by short hairpin RNA (shRNA) prevents gelatin degradation and invadopodia.

The authors have observed a dynamic localization of Sept9_i1 during invadopodia formation. At the beginning of invadopodia stimulation (12 hrs) spet9_i1 is located in proximal part (12 of the invadopodia after which it can be found either throughout or only in the distal part (24 hrs).

Since TKS5 and cortactin are both key factor to invadopodia formation, the authors looked whether sept9_i1 could impact these two factors. They showed that sept9_i1 plays a role in TKS5 and cortactin cluster formation which are located at the cell membrane and around the nucleus. Indeed Sept9_i1 knockdown affects TKS5 and cortactin subcellular organization.

Interestingly, in this first part the authors show that sept9-i1 is important for invadopodia formation and maturation through its association with TKS5.

 

  • Sept9_i1: a bodyguard for the nucleus.

Knowing that invadopodia formation starts under the nucleus, spet9-i1 could be located near to it. By using super-resolution confocal microscopy, the authors found that Sept9_i1 is in the ventral part and in basolateral part of the nucleus. Indeed, Sept9-i1 colocalized with LaminA/C and seems to be intercalated between nucleoporins. However, why is sept9_i1 appended to the nuclear envelope? Surprisingly, Sept9_i1 knockdown led to a nucleus with many wrinkles enriched in laminA/C and nucleoporins compared to control and sept9_i2. The authors speculated that Sept9_i1 could act like lamins and control nuclear rigidity outside it. To confirm this hypothesis, they overexpressed lamin A in Sept9_i1 depleted cells. Lamin A rescued the nuclear shape and the TSK5 cluster numbers. Therefore, the formation of invadopodia seems to be linked to nuclear mechanical properties. Indeed, the authors propose a new mechanism where sept9_i1 mechanically controls the rigidity of the nucleus and invadopodia formation.

In this study, the authors highlighte a new invadopodia factor and a new nuclear mechanobiology factors: Sept9_i1. They conclude that Sept9_i1 allows a functional connection between the nucleus and invadopodia formation. It acts as a nuclear morphology protector, which is important for invadopodia formation itself. Indeed, they propose that a rigid nucleus is essential to allow actin polymerization and support forces generated by the formation of the strong actin core at the plasma membrane under the nucleus.  Finally, invadopodia formation at the juxtanuclear plasma membrane allows ECM degradation to promote nucleus translocation without drastic deformation. Sept9_i1 seems to be a new metastatic factor in breast cancer which is linked to nuclear mechanics.

 

Why I picked this preprint.

Understanding the nuclear mechanics during cancer progression and how cancer cells can manage invasion with this “big ball” inside remain essential questions. This preprint offers a new answer that may advance our knowledge of the cell invasion mechanisms and nuclear mechanics during metastasis.

I am really interested in the non-genomic role of the nucleus, nuclear physical properties and nuclear-mechanotransduction. In this preprint, I really like the idea that there can be a protective outer nuclear barrier (Sept9_i1) to complement the inner nuclear barrier (lamins). Both of them control the nuclear rigidity to avoid nuclear deformation during cancer metastasis and importantly gene expression modification.

 

Questions for the authors.

Q1. Have you looked at the Sept9_i1 dynamics during nuclear translocation?

Q2. Is it possible that the “external wall” (Sept9_i1) and the “internal wall” interact to enhance the nuclear rigidity? As you mentioned in your discussion Sept9_i1 could interact with the LINC complex. Consequently, it will be very interesting for future studies to see if LINC complex depletion affects spetin organization and nuclear shape. Or if overexpression of it can also rescue the phenotype. And to observe if sept9_i1 colocalizes with the LINC complex. However, in some types of breast cancer the LINC complex is downregulated [8]. As a result, I am wondering if the LINC complex could be involved in this process at least in some types of breast cancer. We can also speculate that if the LINC complex is downregulated, the oncegene sept9_i1 could compensate for its loss. I wonder what is your thoughts are these fundamental questions.

Q3. Did you try to knock down lamins to observe the sept9_i1 dynamics?

Q4. Your study is about cancer cell behavior during invasion. Do you think this kind of septin organization can be observed in normal cells, and play a similar role in nuclear rigidity? For example, for cells which have to support lot of tension. And in your opinion, could this mechanisms also exist during physiological cell migration? For example, during development.

 

References.

  1. Linder, S., et al., Mechanisms and roles of podosomes and invadopodia. Nat Rev Mol Cell Biol, 2023. 24(2): p. 86-106.
  2. Blouw, B., et al., A role for the podosome/invadopodia scaffold protein Tks5 in tumor growth in vivo. Eur J Cell Biol, 2008. 87(8-9): p. 555-67.
  3. Ferrari, R., et al., MT1-MMP directs force-producing proteolytic contacts that drive tumor cell invasion. Nat Commun, 2019. 10(1): p. 4886.
  4. Revach, O.Y., et al., Mechanical interplay between invadopodia and the nucleus in cultured cancer cells. Sci Rep, 2015. 5: p. 9466.
  5. Spiliotis, E.T. and K. Nakos, Cellular functions of actin- and microtubule-associated septins. Curr Biol, 2021. 31(10): p. R651-R666.
  6. Benoit, B., C. Poüs, and A. Baillet, Septins as membrane influencers: direct play or in association with other cytoskeleton partners. Front Cell Dev Biol, 2023. 11: p. 1112319.
  7. Connolly, D., et al., Septin 9 isoform expression, localization and epigenetic changes during human and mouse breast cancer progression. Breast Cancer Res, 2011. 13(4): p. R76.
  8. Matsumoto, A., et al., Global loss of a nuclear lamina component, lamin A/C, and LINC complex components SUN1, SUN2, and nesprin-2 in breast cancer. Cancer Med, 2015. 4(10): p. 1547-57.

 

Tags: invadopodia, nucleus, septin

Posted on: 31 July 2023

doi: https://doi.org/10.1242/prelights.35224

Read preprint (No Ratings Yet)

Author's response

Elias T. Spiliotis shared

A1. No, we have not. Septin filaments have been extensively reported to localize near and along the nuclear surface, but surprisingly the relationship between septins and the nuclear envelope has not garnered any attention. Our findings were somewhat fortuitous as our original focus was strictly on invadopodia. We turned to the nucleus when we observed that Sept9_i1 knock-down resulted in dispersion of invadopodia components along the nuclear rim. We plan to look at septin organization and dynamics around the nucleus in conditions of confined migration in 3D ECMs and microchannels.

A2. Components of the LINC complex are good candidates for linking Sept9_i1 to the nuclear membrane. Nesprins interact with actin, microtubules and intermediate filaments, so it’s likely that there is also a direct link with septin filaments. If the Sept9_i1 interaction with the nuclear envelope is via LINC, it would be hard to compensate LINC downregulation. However, if it binds the nuclear membrane independently of LINC, it’s possible to compensate LINC downregulation.

Our findings point primarily to a Sept9_i1 function on the cytoplasmic side of the nucleus, but Sept9_i1 has a nuclear localization signal and has been observed to accumulate in nucleoli. Therefore, we cannot exclude the possibility of Sept9_i1 reinforcing nuclear rigidity on the nucleoplasmic side of the nucleus.

A3. In the revision stages of the manuscript, we generated plasmids that expressed concomitantly lamin A shRNA and GFP-Sept9_i1 to explore whether GFP-Sept9_i1 can rescue defects caused by lamin A depletion. We did not look at Sept9_i1 dynamics.

A4. Yes, absolutely. We hypothesize that septins are capable of tuning the mechanical properties of the nucleus in a variety of cell types and physiological or developmental settings, and in response to external or internal stimuli. There are also implications for genomic stability and the mechanoregulation of gene expression. Our findings provide a new perspective on the alterations of global transcriptomic profiles, which were reported by Cristina Montagna’s group in response to the over-expression of certain Sept9 isoforms.

Have your say

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Sign up to customise the site to your preferences and to receive alerts

Register here

preLists in the cancer biology category:

CSHL 87th Symposium: Stem Cells

Preprints mentioned by speakers at the #CSHLsymp23

 



List by Alex Eve

Journal of Cell Science meeting ‘Imaging Cell Dynamics’

This preList highlights the preprints discussed at the JCS meeting 'Imaging Cell Dynamics'. The meeting was held from 14 - 17 May 2023 in Lisbon, Portugal and was organised by Erika Holzbaur, Jennifer Lippincott-Schwartz, Rob Parton and Michael Way.

 



List by Helen Zenner

CellBio 2022 – An ASCB/EMBO Meeting

This preLists features preprints that were discussed and presented during the CellBio 2022 meeting in Washington, DC in December 2022.

 



List by Nadja Hümpfer et al.

Fibroblasts

The advances in fibroblast biology preList explores the recent discoveries and preprints of the fibroblast world. Get ready to immerse yourself with this list created for fibroblasts aficionados and lovers, and beyond. Here, my goal is to include preprints of fibroblast biology, heterogeneity, fate, extracellular matrix, behavior, topography, single-cell atlases, spatial transcriptomics, and their matrix!

 



List by Osvaldo Contreras

Single Cell Biology 2020

A list of preprints mentioned at the Wellcome Genome Campus Single Cell Biology 2020 meeting.

 



List by Alex Eve

ASCB EMBO Annual Meeting 2019

A collection of preprints presented at the 2019 ASCB EMBO Meeting in Washington, DC (December 7-11)

 



List by Madhuja Samaddar et al.

Lung Disease and Regeneration

This preprint list compiles highlights from the field of lung biology.

 



List by Rob Hynds

Anticancer agents: Discovery and clinical use

Preprints that describe the discovery of anticancer agents and their clinical use. Includes both small molecules and macromolecules like biologics.

 



List by Zhang-He Goh

Biophysical Society Annual Meeting 2019

Few of the preprints that were discussed in the recent BPS annual meeting at Baltimore, USA

 



List by Joseph Jose Thottacherry

Also in the cell biology category:

‘In preprints’ from Development 2022-2023

A list of the preprints featured in Development's 'In preprints' articles between 2022-2023

 



List by Alex Eve, Katherine Brown

preLights peer support – preprints of interest

This is a preprint repository to organise the preprints and preLights covered through the 'preLights peer support' initiative.

 



List by preLights peer support

The Society for Developmental Biology 82nd Annual Meeting

This preList is made up of the preprints discussed during the Society for Developmental Biology 82nd Annual Meeting that took place in Chicago in July 2023.

 



List by Joyce Yu, Katherine Brown

CSHL 87th Symposium: Stem Cells

Preprints mentioned by speakers at the #CSHLsymp23

 



List by Alex Eve

Journal of Cell Science meeting ‘Imaging Cell Dynamics’

This preList highlights the preprints discussed at the JCS meeting 'Imaging Cell Dynamics'. The meeting was held from 14 - 17 May 2023 in Lisbon, Portugal and was organised by Erika Holzbaur, Jennifer Lippincott-Schwartz, Rob Parton and Michael Way.

 



List by Helen Zenner

9th International Symposium on the Biology of Vertebrate Sex Determination

This preList contains preprints discussed during the 9th International Symposium on the Biology of Vertebrate Sex Determination. This conference was held in Kona, Hawaii from April 17th to 21st 2023.

 



List by Martin Estermann

Alumni picks – preLights 5th Birthday

This preList contains preprints that were picked and highlighted by preLights Alumni - an initiative that was set up to mark preLights 5th birthday. More entries will follow throughout February and March 2023.

 



List by Sergio Menchero et al.

CellBio 2022 – An ASCB/EMBO Meeting

This preLists features preprints that were discussed and presented during the CellBio 2022 meeting in Washington, DC in December 2022.

 



List by Nadja Hümpfer et al.

Fibroblasts

The advances in fibroblast biology preList explores the recent discoveries and preprints of the fibroblast world. Get ready to immerse yourself with this list created for fibroblasts aficionados and lovers, and beyond. Here, my goal is to include preprints of fibroblast biology, heterogeneity, fate, extracellular matrix, behavior, topography, single-cell atlases, spatial transcriptomics, and their matrix!

 



List by Osvaldo Contreras

EMBL Synthetic Morphogenesis: From Gene Circuits to Tissue Architecture (2021)

A list of preprints mentioned at the #EESmorphoG virtual meeting in 2021.

 



List by Alex Eve

FENS 2020

A collection of preprints presented during the virtual meeting of the Federation of European Neuroscience Societies (FENS) in 2020

 



List by Ana Dorrego-Rivas

Planar Cell Polarity – PCP

This preList contains preprints about the latest findings on Planar Cell Polarity (PCP) in various model organisms at the molecular, cellular and tissue levels.

 



List by Ana Dorrego-Rivas

BioMalPar XVI: Biology and Pathology of the Malaria Parasite

[under construction] Preprints presented at the (fully virtual) EMBL BioMalPar XVI, 17-18 May 2020 #emblmalaria

 



List by Dey Lab, Samantha Seah

1

Cell Polarity

Recent research from the field of cell polarity is summarized in this list of preprints. It comprises of studies focusing on various forms of cell polarity ranging from epithelial polarity, planar cell polarity to front-to-rear polarity.

 



List by Yamini Ravichandran

TAGC 2020

Preprints recently presented at the virtual Allied Genetics Conference, April 22-26, 2020. #TAGC20

 



List by Maiko Kitaoka et al.

3D Gastruloids

A curated list of preprints related to Gastruloids (in vitro models of early development obtained by 3D aggregation of embryonic cells). Updated until July 2021.

 



List by Paul Gerald L. Sanchez and Stefano Vianello

ECFG15 – Fungal biology

Preprints presented at 15th European Conference on Fungal Genetics 17-20 February 2020 Rome

 



List by Hiral Shah

ASCB EMBO Annual Meeting 2019

A collection of preprints presented at the 2019 ASCB EMBO Meeting in Washington, DC (December 7-11)

 



List by Madhuja Samaddar et al.

EMBL Seeing is Believing – Imaging the Molecular Processes of Life

Preprints discussed at the 2019 edition of Seeing is Believing, at EMBL Heidelberg from the 9th-12th October 2019

 



List by Dey Lab

Autophagy

Preprints on autophagy and lysosomal degradation and its role in neurodegeneration and disease. Includes molecular mechanisms, upstream signalling and regulation as well as studies on pharmaceutical interventions to upregulate the process.

 



List by Sandra Malmgren Hill

Lung Disease and Regeneration

This preprint list compiles highlights from the field of lung biology.

 



List by Rob Hynds

Cellular metabolism

A curated list of preprints related to cellular metabolism at Biorxiv by Pablo Ranea Robles from the Prelights community. Special interest on lipid metabolism, peroxisomes and mitochondria.

 



List by Pablo Ranea Robles

BSCB/BSDB Annual Meeting 2019

Preprints presented at the BSCB/BSDB Annual Meeting 2019

 



List by Dey Lab

MitoList

This list of preprints is focused on work expanding our knowledge on mitochondria in any organism, tissue or cell type, from the normal biology to the pathology.

 



List by Sandra Franco Iborra

ASCB/EMBO Annual Meeting 2018

This list relates to preprints that were discussed at the recent ASCB conference.

 



List by Dey Lab, Amanda Haage
Close