scholarly journals Selective migration of terminally differentiating cells from the basal layer of cultured human epidermis.

1984 ◽  
Vol 98 (1) ◽  
pp. 16-21 ◽  
Author(s):  
F M Watt
Keyword(s):  
Calcium Ion ◽  
Molecular Basis ◽  
Culture Medium ◽  
Basal Layer ◽  
Terminal Differentiation ◽  
Human Keratinocytes ◽  
Ion Concentration ◽  
Culture Substrate ◽  
Layer I ◽  
Calcium Ion Concentration

How terminally differentiating cells are selectively expelled from the basal layer of epidermis has been a source of interest and speculation for many years. The problem can now be studied in culture, using involucrin synthesis as an early marker of terminal differentiation in human keratinocytes. When keratinocytes are forced to grow as a monolayer by reducing the calcium ion concentration of the culture medium, they still begin to synthesize involucrin. Raising the level of calcium ions induces stratification, and cells that are synthesizing involucrin are selectively expelled from the basal layer. I have found that during calcium-induced stratification no new proteins or glycoproteins are synthesized, and the rate of cell division does not change. Movement of involucrin-positive cells out of the basal layer was found to be unaffected by cycloheximide, tunicamycin, or cytosine arabinoside. These results suggest that keratinocytes growing as a monolayer already have the necessary properties to determine their position when stratification is induced. Addition of calcium simply allows formation of desmosomes and other intimate cell contacts required for stratification. The properties of involucrin-positive cells that determine their suprabasal position include a reduced affinity for the culture substrate and preferential adhesion to other cells at the same stage of terminal differentiation. The molecular basis of these adhesive changes is discussed.

scholarly journals Calcium-induced reorganization of desmosomal components in cultured human keratinocytes.

1984 ◽  
Vol 99 (6) ◽  
pp. 2211-2215 ◽  
Author(s):  
F M Watt ◽  
D L Mattey ◽  
D R Garrod
Keyword(s):  
Calcium Ions ◽  
Calcium Ion ◽  
Culture Medium ◽  
Human Keratinocytes ◽  
Preliminary Evidence ◽  
Ion Concentration ◽  
Intercellular Contact ◽  
Keratin Filaments ◽  
Entire Cell ◽  
Calcium Ion Concentration

We used antibodies raised against individual desmosomal components to study calcium-induced desmosome formation in human keratinocytes. When keratinocytes are forced to grow as a monolayer by reducing the level of calcium ions in the culture medium, there is little contact between adjacent cells. Raising the level of calcium ions rapidly induces desmosome formation, and stratification occurs within 24 h. We found that before addition of calcium the 115,000- and 100,000-mol-wt core glycoproteins were distributed over the entire cell surface, whereas the plaque proteins (205,000 and 230,000 mol wt), the 82,000- and 86,000-mol-wt proteins, and the 150,000-mol-wt glycoprotein were located throughout the cytoplasm. 15 min after increasing the calcium ion concentration, all of these molecules appeared at the cell margins. The intensity of peripheral staining increased over the next 2 h and during this time the distribution of keratin filaments changed from predominantly perinuclear to extend throughout the cytoplasm. Keratinocytes could be dissociated with EDTA for up to 2 h after exposure to calcium. After 3 h of exposure to calcium the cells were no longer susceptible to EDTA dissociation and staining for desmosomal plaque antigens persisted in regions of intercellular contact. Desmosomal staining in stratified cultures became greatly reduced within 24 h of lowering the calcium ion concentration again. We have preliminary evidence that stratification occurs by breakdown of desmosomes at lateral surfaces and reformation at surfaces of contact between basal and suprabasal cells, rather than by rearrangement of existing desmosomes. Involucrin-positive cells in the monolayer appeared to contain more 205,000- and 230,000-mol-wt proteins free in the cytoplasm than involucrin-negative cells.

Model of short-term regulation of calcium-ion concentration

SIMULATION ◽  
1979 ◽  
Vol 32 (6) ◽  
pp. 193-204 ◽  
Author(s):  
George G. Járos ◽  
Thomas G. Coleman ◽  
Arthur C. Guyton
Keyword(s):  
Calcium Ion ◽  
Ion Concentration ◽  
Short Term ◽  
Calcium Ion Concentration

Bile canalicular contraction in the isolated hepatocyte doublet is related to an increase in cytosolic free calcium ion concentration

2008 ◽  
Vol 8 (3) ◽  
pp. 178-183 ◽  
Author(s):  
Sumio Watanabe ◽  
Masahiro Tomono ◽  
Makoto Takeuchi ◽  
Tsuneo Kitamura ◽  
Miyoko Hirose ◽  
...  
Keyword(s):  
Calcium Ion ◽  
Ion Concentration ◽  
Free Calcium ◽  
Cytosolic Free Calcium ◽  
Bile Canalicular Contraction ◽  
Calcium Ion Concentration

scholarly journals The gravistimulation-induced very slow Ca2+ increase in Arabidopsis seedlings requires MCA1, a Ca2+-permeable mechanosensitive channel

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Masataka Nakano ◽  
Takuya Furuichi ◽  
Masahiro Sokabe ◽  
Hidetoshi Iida ◽  
Hitoshi Tatsumi
Keyword(s):  
Calcium Ion ◽  
Channel Blocker ◽  
Upright Position ◽  
Ion Concentration ◽  
Early Event ◽  
Free Calcium ◽  
Permeable Channel ◽  
Mechanosensitive Ion Channel ◽  
And Function ◽  
Calcium Ion Concentration

AbstractGravity is a critical environmental factor affecting the morphology and function of plants on Earth. Gravistimulation triggered by changes in the gravity vector induces an increase in the cytoplasmic free calcium ion concentration ([Ca2+]c) as an early process of gravity sensing; however, its role and molecular mechanism are still unclear. When seedlings of Arabidopsis thaliana expressing apoaequorin were rotated from the upright position to the upside-down position, a biphasic [Ca2+]c-increase composed of a fast-transient [Ca2+]c-increase followed by a slow [Ca2+]c-increase was observed. We find here a novel type [Ca2+]c-increase, designated a very slow [Ca2+]c-increase that is observed when the seedlings were rotated back to the upright position from the upside-down position. The very slow [Ca2+]c-increase was strongly attenuated in knockout seedlings defective in MCA1, a mechanosensitive Ca2+-permeable channel (MSCC), and was partially restored in MCA1-complemented seedlings. The mechanosensitive ion channel blocker, gadolinium, blocked the very slow [Ca2+]c-increase. This is the first report suggesting the possible involvement of MCA1 in an early event related to gravity sensing in Arabidopsis seedlings.

Fura-2 fluorescence is localized to mitochondria in endothelial cells

1987 ◽  
Vol 253 (5) ◽  
pp. C744-C747 ◽  
Author(s):  
S. F. Steinberg ◽  
J. P. Bilezikian ◽  
Q. Al-Awqati
Keyword(s):  
Endothelial Cells ◽  
Calcium Ion ◽  
Cytosolic Calcium ◽  
Ion Concentration ◽  
Homogeneous Distribution ◽  
Aortic Endothelial Cells ◽  
Fura 2 ◽  
Bovine Aortic Endothelial Cells ◽  
Calcium Ion Concentration ◽  
Aortic Endothelial

The new, highly fluorescent, calcium-sensitive dye, fura-2, can be loaded nondisruptively into intact cells by means of its permeant ester and used to measure the free calcium ion concentration in individual cells. For fura-2 to signal cytosolic calcium, it must be distributed homogeneously and exclusively throughout the cytoplasmic space. However, microscopic examination of bovine aortic endothelial cells loaded with fura-2 by exposure to its permeant ester reveals fluorescence associated with discrete intracellular structures rather than the homogeneous distribution expected for a cytosolic stain. Simultaneous labeling of bovine aortic endothelial cells with fura-2 and rhodamine 123 (a mitochondrial fluorescent vital stain) identifies these structures as mitochondria. Subcellular dye localizations are not observed when the cells are loaded with other putative cytosolic stains that gain access to the cytosol by means of a membrane permeant ester. Both carboxyfluorescein and indo-1 (another member of the family of second generation calcium indicators) stain the cytoplasm diffusely. It is suggested that fura-2 fluorescence accumulates in certain cells in association with mitochondria. It is important to assess the intracellular distribution of fura-2 when this indicator is used to measure the free cytosolic calcium ion concentration.

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