Vol 49, No 2 (2011)
Original paper
Submitted: 2011-12-19
Published online: 2011-07-11
Characteristics of weak base-induced vacuoles formed around individual acidic organelles
Hiromi Hiruma, Tadashi Kawakami
DOI: 10.5603/FHC.2011.0038
·
Folia Histochem Cytobiol 2011;49(2):272-279.
Vol 49, No 2 (2011)
ORIGINAL PAPERS
Submitted: 2011-12-19
Published online: 2011-07-11
Abstract
We have previously found that the weak base 4-aminopyridine induces Brownian motion of acidic
organelles around which vacuoles are formed, causing organelle traffic disorder in neurons. Our present
study investigated the characteristics of vacuoles induced by weak bases (NH4Cl, aminopyridines, and chloroquine)
using mouse cells. Individual vacuoles included acidic organelles identified by fluorescent protein
expression. Mitochondria and actin filaments were extruded outside the vacuoles, composing the vacuole
rim. Staining with amine-reactive fluorescence showed no protein/amino acid content in vacuoles. Thus,
serous vacuolar contents are probably partitioned by viscous cytosol, other organelles, and cytoskeletons,
but not membrane. The weak base (chloroquine) was immunochemically detected in intravacuolar organelles,
but not in vacuoles. Early vacuolization was reversible, but long-term vacuolization caused cell death. The
vacuolization and cell death were blocked by the vacuolar H+-ATPase inhibitor and Cl–-free medium. Staining
with LysoTracker or LysoSensor indicated that intravacuolar organelles were strongly acidic and vacuoles
were slightly acidic. This suggests that vacuolization is caused by accumulation of weak base and H+ in
acidic organelles, driven by vacuolar H+-ATPase associated with Cl– entering, and probably by subsequent
extrusion of H+ and water from organelles to the surrounding cytoplasm. (Folia Histochemica et Cytobiologica
2011; Vol. 49, No. 2, pp. 272–279)
Abstract
We have previously found that the weak base 4-aminopyridine induces Brownian motion of acidic
organelles around which vacuoles are formed, causing organelle traffic disorder in neurons. Our present
study investigated the characteristics of vacuoles induced by weak bases (NH4Cl, aminopyridines, and chloroquine)
using mouse cells. Individual vacuoles included acidic organelles identified by fluorescent protein
expression. Mitochondria and actin filaments were extruded outside the vacuoles, composing the vacuole
rim. Staining with amine-reactive fluorescence showed no protein/amino acid content in vacuoles. Thus,
serous vacuolar contents are probably partitioned by viscous cytosol, other organelles, and cytoskeletons,
but not membrane. The weak base (chloroquine) was immunochemically detected in intravacuolar organelles,
but not in vacuoles. Early vacuolization was reversible, but long-term vacuolization caused cell death. The
vacuolization and cell death were blocked by the vacuolar H+-ATPase inhibitor and Cl–-free medium. Staining
with LysoTracker or LysoSensor indicated that intravacuolar organelles were strongly acidic and vacuoles
were slightly acidic. This suggests that vacuolization is caused by accumulation of weak base and H+ in
acidic organelles, driven by vacuolar H+-ATPase associated with Cl– entering, and probably by subsequent
extrusion of H+ and water from organelles to the surrounding cytoplasm. (Folia Histochemica et Cytobiologica
2011; Vol. 49, No. 2, pp. 272–279)
Keywords
acidic organelles; cytoplasmic vacuoles; vacuolar H+-ATPase; weak base
Title
Characteristics of weak base-induced vacuoles formed around individual acidic organelles
Journal
Folia Histochemica et Cytobiologica
Issue
Vol 49, No 2 (2011)
Article type
Original paper
Pages
272-279
Published online
2011-07-11
Page views
1704
Article views/downloads
2134
DOI
10.5603/FHC.2011.0038
Bibliographic record
Folia Histochem Cytobiol 2011;49(2):272-279.
Keywords
acidic organelles
cytoplasmic vacuoles
vacuolar H+-ATPase
weak base
Authors
Hiromi Hiruma
Tadashi Kawakami