Hotulainen Lab

August 11, 2023

PhD Defense – Pushpa Khanal
Molecular regulation of the dendritic spine initiation

Opponent Professor Martin Korte, Technische Universität Braunschweig, Germany

We were honoured to have Martin Korte as an opponent! Thank you Martin and congratulations Pushpa! Thank you also to Juha Voipio, who served as an official custos.

PhD work of Pushpa Khanal was based on four original publications:
1) Rimante Minkeviciene, Iryna Hlushchenko, Anaïs Virenque, Lauri Lahti, Pushpa Khanal, Mikko Kettunen, Tuomas Rauramaa, Arto Koistinen, Riikka Immonen, Ville Leinonen, Francesco M. Noé, and Pirta Hotulainen. “MIM-deficient mice exhibit anatomical changes in dendritic spines, cortex volume and brain ventricles, and functional changes in motor coordination and learning.” Frontiers in Molecular Neuroscience. 12:276, 2019.
2) Pushpa Khanal and Pirta Hotulainen. “Dendritic Spine Initiation in Brain Development, Learning and Diseases and Impact of BARDomain Proteins.’’ Cells. 10(9):2392, 2021.
3) Pushpa Khanal, Zoran Boskovic, Lauri Lahti, Aruna Ghimire, Rimante Minkeviciene, Patricio Opazo, Pirta Hotulainen. ‘‘Gas7 is a novel dendritic spine initiation factor.’’ eNeuro. ENEURO.0344- 22.2023, 2023.
4) Iryna Hlushchenko, Pushpa Khanal, Amr Abouelezz, Ville O. Paavilainen, Pirta Hotulainen. “ASD-Associated De Novo Mutations in Five Actin Regulators Show Both Shared and Distinct Defects in Dendritic Spines and Inhibitory Synapses in Cultured Hippocampal Neurons.” Frontiers in Cellular Neuroscience. 12:217, 2018.

News

May 22, 2020

Our paper is out!

This was a long and relatively big project with fruitful collaboration of many laboratories, many thanks to all!

HIGHLIGHTS
-Tropomyosin isoform Tpm3.1 co-localizes with the actin cytoskeleton in the AIS
-Tpm3.1 inhibition led to a less organized AIS actin cytoskeleton
-Perturbation of Tpm3.1 function reduced the accumulation of AIS scaffolding proteins
-Tpm3.1 inhibition compromised cargo sorting and rapidly reduced firing frequency

Abouelezz et al., iScience. May 22, 2020

February 27, 2020

PhD Defense – Amr Abouelezz
The Structure and Dynamics of the Actin Cytoskeleton in the Axon Initial Segment

Opponent Christophe Leterrier, CNRS-Aix Marseille University, France.

We were happy to host Christophe Leterrier as an opponent! Although the discussion was very tough, Amr passed the test with flying colors! Thank you Christophe and congratulations Amr! Thank you also to Juha Voipio, who served as an official custos.

PhD work of Amr was based on two original publications:
1) Abouelezz A, Micinski D, Lipponen A, Hotulainen P. (2019) Sub-membranous actin rings in the axon initial segment are resistant to the action of latrunculin. Biol Chem. 400:1141-1146.
2) Abouelezz A, Stefen H, Segerstråle M, Micinski D, Minkeviciene R, Lahti L, Hardeman EC, Gunning PW, Hoogenraad CC, Taira T, Fath T, Hotulainen P. (2020) Tropomyosin Tpm3.1 Is Required to Maintain the Structure and Function of the Axon Initial Segment. iScience. 23:101053.

January 20, 2020

New Spotlight article is out!

Amr and Pirta wrote a Spotlight in the Journal of Cell Biology highlighting a nice recent paper from the group of Matthew N. Rasband in Houston, TX, USA. In this article, Torii et al. showed that transient expression and AIS localization of NuMA1 stabilizes the developing AIS by inhibiting endocytosis and removal of AIS proteins.

August 16, 2019

PhD Defense –Iryna Hlushchenko
Actin regulation in dendritic spines:
from synaptic plasticity to animal behavior and human neurodevelopmental disorders.

Opponent Marina Mikhaylova, University Medical Center Hamburg-Eppendorf, Germany

We were happy to host Marina Mikhaylova as an opponent! Marina was very well prepared and did excellent questions but Iryna showed her skills and gave also excellent answers! Thank you Marina and congratulations Iryna! Thank you also to Juha Voipio, who served as an official custos.

PhD work of Iryna was based on three original publications and one review article:

1) Hlushchenko I, Koskinen M, Hotulainen P. (2016) Dendritic spine actin dynamics in neuronal maturation and synaptic plasticity. Cytoskeleton 73:435-41.
2) Hlushchenko I, Hotulainen P. (2019) Chemical LTD, but not LTP, induces transient accumulation of gelsolin in dendritic spines. Biol Chem. 400:1129-1139.
3) Minkeviciene R, Hlushchenko I, Virenque A, Lahti L, Khanal P, Rauramaa T, Koistinen A, Leinonen V, Noé FM, Hotulainen, P. (2019) MIM-Deficient Mice Exhibit Anatomical Changes in Dendritic Spines, Cortex Volume and Brain Ventricles, and Functional Changes in Motor Coordination and Learning. Frontiers in Mol. Neurosci. 12, 276.
4) Hlushchenko I, Khanal P, Abouelezz A, Paavilainen VO, Hotulainen P. (2018) ASD-Associated De Novo Mutations in Five Actin Regulators Show Both Shared and Distinct Defects in Dendritic Spines and Inhibitory Synapses in Cultured Hippocampal Neurons. Front Cell Neurosci.12:217.