download report - Istituto Pasteur

P a r t i c i p a n t s :
Silvia Bonaccorsi, Maria Grazia Giansanti, Patrizia
Somma, Fiammetta Vernì, researchers; Elisabetta
Bucciarelli, Gianluca Cestra, post-doc fellows; Claudia
Pellacani, PhD student; Giorgio Belloni, technician.
C o l l a b o r a t i o n s :
Stanford University, USA (Prof. Margareth Fuller); Cornell
University, USA (Prof. Michel L. Goldberg).
Report of activity
During animal cell cytokinesis, constriction of the
acto-myosin ring leads to the formation of a furrow
in the plasma membrane, which invaginates until the
two daughter cells remain connected by a thin cytoplasmic
bridge, called the midbody. This bridge is
ultimately cleaved during the final step of cytokinesis,
named abscisssion, which results in the complete
separation of daughter cells. Both cleavage furrow
ingression and abscission require substantial membrane
remodelling. Membrane addition to the invaginating
furrow involves vesicle delivery through both
the secretory and the endocytic pathways. In the
secretory pathway, vesicles are transported from the
endoplasmic reticulum (ER) to the Golgi and then to
the plasma membrane. In the endocytic pathway,
plasma membrane-derived vesicles proceed to the
recycling endosome (RE), which directs them back to
the plasma membrane.
Our goal is elucidation of the molecular mechanisms
underlying membrane addition at the advancing
cleavage furrow of Drosophila spermatocytes. We
have recently identified mutations in six genes
required for furrow ingression during meiotic
cytokinesis of Drosophila males. All these genes
encode products involved in membrane trafficking:
Zw10, Rab1, the Exocist complex components
Exo84 and Sec8, and the ortholog of PACS-1. We
plan to define the roles of these proteins in furrow
Principal investigator: Maurizio Gatti
Professor of Genetics
Dipartimento di Genetica e Biologia Molecolare
Tel: (+39) 06 49912842; Fax: (+39) 06 4456866
maurizio.gatti@uniroma1.it
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Molecular genetics of eukaryotes - AREA 3
The role of membrane trafficking in Drosophila cytokinesis
ingression, and investigate their functional relationships
with other proteins involved in membrane traffic
during cytokinesis.
In the past two years we have carried out three main
research projects.
The role for of bond in furrow ingression
during cytokinesis in Drosophila
spermatocytes
Recent work has shown that plasma membrane lipids
influence membrane biophysical properties such as
membrane curvature and elasticity and play an active
role in cell function. We have found that mutations in
the gene bond, which encodes a Drosophila member of
the family of Elovl proteins that mediate elongation
of very-long-chain fatty acids, block or dramatically
slow cleavage-furrow ingression during early
telophase in dividing spermatocytes. Bond shares
sequence motifs with human and yeast Elovl family
members, including five to seven predicted transmembrane
domains, and can substitute for elovl
genes in S. cerevisiae. In bond mutant cells at late
stages of meiotic division, the contractile ring frequently
detaches from the cortex and constricts or
collapses to one side of the cell, and the cleavage furrow
regresses. These findings implicate very-longchain
fatty acids or their derivative complex lipids in
allowing supple membrane deformation and the stable
connection of cortical contractile components to
the plasma membrane during cell division.
brunelleschi (bru) is required to regulate
Rab11 behavior during meiotic cytokinesis in
Drosophila males
We have found that successful furrow ingression during
meiotic cytokinesis in Drosophila males requires
function of the gene brunelleschi (bru), which encodes
the ortholog of the yeast transport protein particle
(TRAPP) II complex subunit, Trs120p. Dividing male
meiotic cells from bru mutants assemble a normal contractile
ring that initiates constriction but fails to con-