Non-muscle myosin II drives critical steps of nematocyst morphogenesis

Niharika Garg; Urška Knez Štibler; Björn Eismann; Moritz Mercker; Bruno Gideon Bergheim; Anna Linn; Patrizia Tuchscherer; Ulrike Engel; Stefan Redl; Anna Marciniak-Czochra; Thomas W Holstein; Michael W Hess; Suat Özbek

doi:10.1016/j.isci.2023.106291

Non-muscle myosin II drives critical steps of nematocyst morphogenesis

iScience. 2023 Feb 28;26(3):106291. doi: 10.1016/j.isci.2023.106291. eCollection 2023 Mar 17.

Authors

Affiliations

¹ University of Heidelberg, Centre for Organismal Studies, Department of Molecular Evolution and Genomics, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany.
² Institute for Applied Mathematics, Interdisciplinary Center for Scientific Computing, Heidelberg University, Im Neuenheimer Feld 205, 69120 Heidelberg, Germany.
³ Nikon Imaging Center at the University of Heidelberg, Bioquant, Heidelberg University, 69120 Heidelberg, Germany.
⁴ Institute of Neuroanatomy, Medical University of Innsbruck, Müllerstrasse 59, 6020 Innsbruck, Austria.
⁵ Institute of Zoology, University of Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria.
⁶ Institute of Histology and Embryology, Medical University of Innsbruck, Müllerstrasse 59, 6020 Innsbruck, Austria.

Abstract

Nematocysts are generated by secretion of proteins into a post-Golgi compartment. They consist of a capsule that elongates into a long tube, which is coiled inside the capsule matrix and expelled during its nano-second discharge deployed for prey capture. The driving force for discharge is an extreme osmotic pressure of 150 bar. The complex processes of tube elongation and invagination under these biomechanical constraints have so far been elusive. Here, we show that a non-muscle myosin II homolog (HyNMII) is essential for nematocyst formation in Hydra. In early nematocysts, HyNMII assembles to a collar around the neck of the protruding tube. HyNMII then facilitates tube outgrowth by compressing it along the longitudinal axis as evidenced by inhibitor treatment and genetic knockdown. In addition, live imaging of a NOWA::NOWA-GFP transgenic line, which re-defined NOWA as a tube component facilitating invagination, allowed us to analyze the impact of HyNMII on tube maturation.

Keywords: Cell biology; Developmental biology.