IPBS Seminar Series - Invadosomes at the nanoscale

Alessandra Cambi

RIMLS, Nijmegen, The Netherlands

MechNanobiology of dendritic cells

Within tissues, cells are subjected to various mechanical forces, including spatial constraints, fluid shear stress and topological cues, each of which contributes to tissue shaping, development and maintenance. How cells interact with and respond to these forces is largely dictated by physical properties of the cells themselves, their neighboring cells and the extracellular matrix (ECM). The process by which cells integrate mechanical stimuli to subsequently translate them into biochemical response is termed mechanotransduction. Tissue stiffness alteration, resulting in disrupted homeostasis of mechanical forces, is involved in many pathologies including pulmonary fibrosis, atherosclerosis and cancer. Despite the importance of mechanotransduction, still little is known about how mechanical forces between cells and their microenvironment contribute to the regulation of tissue organization and function. Specialized leukocytes called dendritic cells (DCs) are key regulators of immune responses. They crawl within tissues patrolling for pathogens or aberrant cells. Upon danger recognition, DCs mature and migrate to lymph nodes to initiate immune responses. During their life-cycle, DCs experience multiple, elastically diverse microenvironments as well as different mechanical stimuli, such as fluid shear variation and cell stretching. This lecture will present novel insights into fundamental biophysical mechanisms regulating DC mechanobiology.

Selected references

• Bolomini-Vittori M, Mennens SFB, Joosten B, Fransen J, Du G, van den Dries K, Cambi A. PLD-dependent phosphatidic acid microdomains are signaling platforms for podosome formation. Sci Rep 2019 Mar 5;9(1):3556
• Mennens SFB1, Bolomini-Vittori M, Weiden J, Joosten B, Cambi A, van den Dries K. Substrate stiffness influences phenotype and function of human antigen-presenting dendritic cells. Sci Rep 2017 Dec 13;7(1):17511
• Meddens MB, Pandzic E, Slotman JA, Guillet D, Joosten B, Mennens S, Paardekooper LM, Houtsmuller AB, van den Dries K, Wiseman PW, Cambi A. Actomyosin-dependent dynamic spatial patterns of cytoskeletal components drive mesoscale podosome organization. Nat Commun 2016 Oct 10;7:13127

Olivier Destaing

IAB, Grenoble

Pushing or cutting, the invadosome dilemma

Invadosomes are protrusive organelles coordinating cell invasion, matrix degradation and migration. Each invadosome unit consists of a core surrounded by a ring of adhesive proteins, that can digest ECM. Besides being apparently antagonists, we conceptualize that both acto-adhesive and ECM degradation functions should finely tune to have an efficient invadosome, through the regulation of specific acto-adhesive proteins or new player of adhesion regulation such as calcium channels.

On the contray with focal adhesions, numerous aspects of the mechanical functions of invadosomes remain unknown, such as importance of the ring or the mechanic of their collective organization. Based on a collaborative work with prof. Salaita's lab, we highlighted new aspects of mechanical properties of invadosomes (Glazier et al., 2019). This work introduced Molecular Tension – Fluorescence Lifetime Imaging Microscopy (MT-FLIM), a FRET-based method, to map receptor tension and clustering on biomimetic fluid interfaces. We demonstrated that invadosomes achieve force balance (between protrusive core and contractile ring) through the application of normal and pN integrin forces in their adhesive rings. This work provides direct evidence of a local model of inavdosome force balance.

Selected references

• Glazier R., Brockman JM., Bartle E., Mattheyses AL., Destaing O.*, Salaita K.*. DNA mechanotechnology reveals that integrin receptors apply pN forces in podosomes on fluid substrates. Nat Commun in press
• De Mets R, Wang I, Balland M, Oddou C, Moreau P, Fourcade B, Albiges-Rizo C, Delon A, Destaing O. Cellular tension encodes local Src-dependent differential β1 and β3 integrin mobility. Mol Biol Cell 2019 Jan 15;30(2):181-190
• Petropoulos C, Oddou C, Emadali A, Hiriart-Bryant E, Boyault C, Faurobert E, Vande Pol S, Kim-Kaneyama JR, Kraut A, Coute Y, Block M, Albiges-Rizo C, Destaing O. Roles of paxillin family members in adhesion and ECM degradation coupling at invadosomes. J Cell Biol 2016 Jun 6;213(5):585-99