scholarly journals Modulation of Protein Kinases and Microtubule-associated Proteins and Changes in Ultrastructure in Female Rat Pituitary Cells: Effects of Estrogen and Bromocriptine

1997 ◽  
Vol 45 (6) ◽  
pp. 805-813 ◽  
Author(s):  
Akira Matsuno ◽  
Susumu Takekoshi ◽  
Naoko Sanno ◽  
Hirotoshi Utsunomiya ◽  
Yoshitaka Ohsugi ◽  
...  
Keyword(s):  
Tau Protein ◽  
Intracellular Transport ◽  
Structural Changes ◽  
Ultrastructural Changes ◽  
Pituitary Cells ◽  
Female Rat ◽  
Cam Kinase ◽  
Microtubule Associated Proteins ◽  
Rat Pituitary ◽  
Associated Proteins

This study focused on the intracellular signal transduction system and microtubule-associated proteins (MAPs), such as MAP-2 and Tau protein. The modulation of these proteins and their correlation with ultrastructural changes were investigated in rat pituitary prolactin (PRL) cells. Adult female Wistar rats were treated with estrogen and bromocriptine and their pituitary glands were removed for analysis of the expression of tubulin, MAP-2, Tau protein, protein kinase C (PKC), and calcium calmodulin (CaM) kinase. Western blot analysis showed that estrogen increased and bromocriptine decreased the expression of PKCα, β1, β2, CaM kinase α, β, MAP-2, and Tau protein. MAP-2 and Tau protein, which are cytosolic proteins, being translated on free ribosomes, were associated with the membrane of whirling rough endoplasmic reticulum (RER) in estrogen-treated cells and dissociated with vesiculated RER induced by bromocriptine. These results suggested that the modulation of MAP-2 and Tau protein may reflect changes of PKC and CaM kinase, and that the quantitative changes and intracellular modulation of MAPs induced by estrogen and bromocriptine, i.e., estrogen-induced association and bromocriptine-induced dissociation of MAP-2 and Tau protein with membrane of RER, may reflect the dynamics of microtubules and are associated with structural changes in the RER and changes in the synthesis and intracellular transport of PRL.

scholarly journals Effects of activin on hormone secretion by single female rat pituitary cells: analysis by cell immunoblot assay

1999 ◽  
Vol 161 (3) ◽  
pp. 375-382 ◽  
Author(s):  
S Miyamoto ◽  
M Irahara ◽  
K Ushigoe ◽  
A Kuwahara ◽  
H Sugino ◽  
...  
Keyword(s):  
Hormone Secretion ◽  
Activin A ◽  
Female Rats ◽  
Pituitary Cells ◽  
Female Rat ◽  
Single Female ◽  
Immunoblot Assay ◽  
Rat Pituitary ◽  
Rat Pituitary Cells ◽  
Lh Secretion

We investigated the effect of activin A on secretion of LH, FSH, and prolactin (PRL) by female cultured rat pituitary cells at the single-cell level by means of the cell immunoblot assay. Anterior pituitary cells from 8-week-old female rats were preincubated with or without activin A for 24 h, after which they were monodispersed and immediately used for cell immunoblot assay. The percentages of LH-, FSH- and PRL-immunoreactive cell blots detected were 5.5, 5.3 and 43.1%, respectively, of all pituitary cells applied to the transfer membrane. The percentage of LH-secreting cells and mean LH secretion per cell did not change after treatment with activin. In contrast, activin significantly increased the percentage of FSH-secreting cells and mean FSH secretion per cell to 136.0 and 114. 5% respectively. In addition, activin significantly decreased the percentage of PRL-secreting cells and mean PRL secretion per cell to 52.2 and 72.0% respectively. These results suggest that (1) activin A has effects on female rat pituitary cells that increase not only the amount of FSH secretion per cell but also the number of FSH-secreting cells, and (2) activin A decreases both the amount of PRL secretion per cell and the number of PRL-secreting cells.

Oestrogen receptor α and β in female rat pituitary cells: An immunochemical study

2008 ◽  
Vol 155 (3) ◽  
pp. 857-868 ◽  
Author(s):  
Miriam González ◽  
Ricardo Reyes ◽  
Carmen Damas ◽  
Rafael Alonso ◽  
Aixa R. Bello
Keyword(s):  
Oestrogen Receptor ◽  
Pituitary Cells ◽  
Female Rat ◽  
Immunochemical Study ◽  
Rat Pituitary ◽  
Oestrogen Receptor Α ◽  
Rat Pituitary Cells

scholarly journals Opto-Katanin: An Optogenetic Tool for Localized Microtubule Disassembly

2021 ◽  
Author(s):  
Joyce C.M. Meiring ◽  
Ilya Grigoriev ◽  
Wilco Nijenhuis ◽  
Lukas C. Kapitein ◽  
Anna Akhmanova
Keyword(s):  
Intracellular Transport ◽  
Experimental Manipulation ◽  
Microtubule Depolymerization ◽  
Microtubule Associated Proteins ◽  
Microtubule Severing ◽  
Associated Proteins ◽  
Dividing Cells ◽  
Chromosome Separation ◽  
Organelle Morphology ◽  
Spatiotemporal Control

Microtubules are major cytoskeletal filaments that drive chromosome separation during cell division, serve as rails for intracellular transport and as a scaffold for organelle positioning. Experimental manipulation of microtubules is widely used in cell and developmental biology, but tools for precise subcellular spatiotemporal control of microtubule integrity are currently lacking. Here, we exploit the dependence of the mammalian microtubule-severing protein katanin on microtubule-targeting co-factors to generate a light-activated system for localized microtubule disassembly that we named opto-katanin. Targeted illumination with blue light induces rapid and localized opto-katanin recruitment and local microtubule depolymerization, which is quickly reversible after stopping light-induced activation. Opto-katanin can be employed to locally perturb microtubule-based transport and organelle morphology in dividing cells and differentiated neurons with high spatiotemporal precision. We show that different microtubule-associated proteins can be used to recruit opto-katanin to microtubules and induce severing, paving the way for spatiotemporally precise manipulation of specific microtubule subpopulations.

scholarly journals MARK/PAR1 kinase is a regulator of microtubule-dependent transport in axons

2004 ◽  
Vol 167 (1) ◽  
pp. 99-110 ◽  
Author(s):  
Eva-Maria Mandelkow ◽  
Edda Thies ◽  
Bernhard Trinczek ◽  
Jacek Biernat ◽  
Eckard Mandelkow
Keyword(s):  
Cell Polarity ◽  
Tau Protein ◽  
Ganglion Cells ◽  
Intrinsic Activity ◽  
Active Movement ◽  
Retinal Ganglion ◽  
Microtubule Associated Proteins ◽  
Cell Components ◽  
Associated Proteins ◽  
Dependent Transport

Microtubule-dependent transport of vesicles and organelles appears saltatory because particles switch between periods of rest, random Brownian motion, and active transport. The transport can be regulated through motor proteins, cargo adaptors, or microtubule tracks. We report here a mechanism whereby microtubule associated proteins (MAPs) represent obstacles to motors which can be regulated by microtubule affinity regulating kinase (MARK)/Par-1, a family of kinases that is known for its involvement in establishing cell polarity and in phosphorylating tau protein during Alzheimer neurodegeneration. Expression of MARK causes the phosphorylation of MAPs at their KXGS motifs, thereby detaching MAPs from the microtubules and thus facilitating the transport of particles. This occurs without impairing the intrinsic activity of motors because the velocity during active movement remains unchanged. In primary retinal ganglion cells, transfection with tau leads to the inhibition of axonal transport of mitochondria, APP vesicles, and other cell components which leads to starvation of axons and vulnerability against stress. This transport inhibition can be rescued by phosphorylating tau with MARK.

scholarly journals The Development of Cell Processes Induced by tau Protein Requires Phosphorylation of Serine 262 and 356 in the Repeat Domain and Is Inhibited by Phosphorylation in the Proline-rich Domains

1999 ◽  
Vol 10 (3) ◽  
pp. 727-740 ◽  
Author(s):  
Jacek Biernat ◽  
Eva-Maria Mandelkow
Keyword(s):  
Tau Protein ◽  
Approximate Model ◽  
Necessary Condition ◽  
Sf9 Cells ◽  
Microtubule Associated Proteins ◽  
Repeat Domain ◽  
Phosphorylation Pattern ◽  
Associated Proteins ◽  
Cell Processes ◽  
A Minor

The differentiation of neurons and the outgrowth of neurites depends on microtubule-associated proteins such as tau protein. To study this process, we have used the model of Sf9 cells, which allows efficient transfection with microtubule-associated proteins (via baculovirus vectors) and observation of the resulting neurite-like extensions. We compared the phosphorylation of tau23 (the embryonic form of human tau) with mutants in which critical phosphorylation sites were deleted by mutating Ser or Thr residues into Ala. One can broadly distinguish two types of sites, the KXGS motifs in the repeats (which regulate the affinity of tau to microtubules) and the SP or TP motifs in the domains flanking the repeats (which contain epitopes for antibodies diagnostic of Alzheimer’s disease). Here we report that both types of sites can be phosphorylated by endogenous kinases of Sf9 cells, and that the phosphorylation pattern of the transfected tau is very similar to that of neurons, showing that Sf9 cells can be regarded as an approximate model for the neuronal balance between kinases and phosphatases. We show that mutations in the repeat domain and in the flanking domains have opposite effects. Mutations of KXGS motifs in the repeats (Ser262, 324, and 356) strongly inhibit the outgrowth of cell extensions induced by tau, even though this type of phosphorylation accounts for only a minor fraction of the total phosphate. This argues that the temporary detachment of tau from microtubules (by phosphorylation at KXGS motifs) is a necessary condition for establishing cell polarity at a critical point in space or time. Conversely, the phosphorylation at SP or TP motifs represents the majority of phosphate (>80%); mutations in these motifs cause an increase in cell extensions, indicating that this type of phosphorylation retards the differentiation of the cells.

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