Navigation Links
Research in the Origin of Microtubules

Researchers at Vanderbilt University Medical Center reveal a surprising new origin for cellular "highways .They report that the Golgi apparatus -- a stack of pancake-shaped compartments that sorts and ships proteins out to their cellular destinations -- is the source of a particular subset of these microscopic fibers.

Scientists have long thought that microtubules, part of the microscopic scaffolding that the cell uses to move things around in order to hold its shape and divide, originated from a tiny structure near the nucleus, called the centrosome.

The findings point to a novel cellular mechanism that may guide cell movement and possibly cancer cell invasion. Microtubules are the largest of the three main types of filaments that make up the cytoskeleton -- a web of microscopic fibers inside the cell.

Microtubules are the largest of the three main types of filaments that make up the cytoskeleton -- a web of microscopic fibers inside the cell.

They form when two globular proteins, alpha- and beta-tubulin, polymerize into long chains, which then assemble into long, hollow tubes. In order to gain a foothold, nascent microtubule "seeds" must be anchored at a structure near the cell's nucleus called the centrosome or microtubule-organizing center (MTOC).

From the MTOC, the growing microtubules launch out in all directions to the cell's periphery. Their rapid assembly and disassembly helps transport proteins throughout the cell and generate polarized (directional) signal distribution that causes cells to move.

While microtubules in some specialized cells can originate from non-centrosomal structures, the centrosome has been considered the main origination point for microtubule "nucleation" in most cells. Until now.

"I've seen that there are lots of microtubules not attached to the centrosome," said Kaverina, assistant professor of Cell and Developmental Biology and senior author on the pap er. "So I am trying to look at their origins."

The Golgi has been suspected to function as an MTOC, explained Kaverina. However, conclusively demonstrating this was impossible before the advent of live-cell imaging techniques that could reveal the true origins of these structures. "The Golgi apparatus is very close to the centrosome," said Kaverina. "So if you're not looking at it precisely, it is hard to distinguish between the centrosome and Golgi."

To get a close look, Kaverina and colleagues tagged the growing ("plus") ends of microtubules in human retinal epithelial cells with a fluorescent molecule, videotaped their growth and carefully followed the tracks back to their origin.

"We show that not only the centrosome, but the Golgi also makes microtubules," Kaverina said. "And unlike centrosomal microtubules, which are radial and symmetric, these microtubules are directional."

They found that microtubules originating at the Golgi are directed toward the cell "front," or the leading edge, of motile cells. Since such an orientation is needed for directional migration, Kaverina hypothesizes that this subset of microtubules may influence cell motility by facilitating the transport of proteins needed for movement to the cell front.

"This new microtubule subset that we discovered directly connects the Golgi to the cell front, so it would be very logical if these microtubules act as ‘tracks' for this delivery," she said.

In addition to identifying this novel site of microtubule nucleation, Kaverina and colleagues also examined the molecular mechanisms governing the process. They found that proteins normally associated with the plus ends of microtubules, called CLASPs, localize to a specific compartment of the Golgi (the Trans Golgi Network) and stabilize the microtubule "seeds" at the Golgi.

Golgi-originating microtubules could also be an important factor influencing how cancer cells invade di stant tissues. Because microtubules play a central role in cell division, cancer drugs like colchicine, vincristine and paclitaxel (Taxol) can block cell division by altering microtubule dynamics.

"Many classic chemotherapy strategies affect microtubules, although it's not quite clear how these drugs influence cancer cells differently than normal cells," said Kaverina. "Both microtubule regulation of proliferation and microtubule regulation of migration and invasion probably contribute to the therapeutic effects."

Therefore, further study of this new subset of microtubules might offer insight into how the invasion of cancer cells into surrounding tissues could be halted.


'"/>




Related medicine news :

1. Kidney Stones - Interesting New Research implicates bacteria as its cause
2. Researchers urge caution in using ear tube surgery
3. Paracetamol May Cause Live Damage Warns Consumer Education and Research Centre
4. Researchers Scale to assess the Severity of Epilepsy in Kids
5. Research of Ritalin
6. Researchers trick Alzheimers Enzyme
7. Researchers find new HIV hiding place
8. A Compilation of recent Diabetes Research articles
9. Research on causes for falling helps develop preventive strategies
10. New standards for Human Research Safety
11. Research on Celiac Disease in children
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:3/30/2017)... ... , ... According to the American Society of Plastic Surgeons (ASPS), over one ... 5 most popular minimally-invasive cosmetic procedures in the country. With summer close, it’s safe ... next 8-10 weeks. For anyone considering a hair removal procedure, there are a few ...
(Date:3/30/2017)... ... , ... Nutrition Education for the Public (NEP), a dietetic ... Seafood Nutrition Partnership (SNP) in presenting “Eating Heart Healthy: Exploring Issues of Low ... students inform consumers about the health benefits of eating a seafood-rich diet. ...
(Date:3/29/2017)... WI (PRWEB) , ... March 29, 2017 , ... ARI ... its exclusive provider of co-op eligible dealer websites for its network of more than ... of professional landscaping and agricultural equipment including rotary and flail mowers and cutters, rear ...
(Date:3/29/2017)... ... ... main cause of hay fever in the United States, with an estimated 95 percent of ... July each year; with the worst time for sufferers being June and July. , ... provide an effective defense against grass pollen; they are proven in independent studies to trap ...
(Date:3/29/2017)... ... March 30, 2017 , ... Sports Brand EXOUS Bodygear announced ... retails normally at $29.97; for the remaining days of March, the price will be ... to a special price of just $10 (regular retail price $19.97). , The special ...
Breaking Medicine News(10 mins):
(Date:3/29/2017)... N.Y. , March 29, 2017  BioSpecifics ... originated and continues to develop collagenase based-therapies with ... histolyticum (CCH) marketed as XIAFLEX ®  in the ... management will present a corporate overview at the ... on Wednesday, April 5, 2017 at 8:00 a.m. ...
(Date:3/29/2017)... Research and Markets has announced the addition of the "Italy ... report to their offering. ... Proton Therapy Market in Italy will double by ... currently three proton therapy centers in Italy that ... Italy , the first patients were treated with proton beams in ...
(Date:3/29/2017)... 29, 2017 Research and Markets has ... 2014 - 2025" report to their offering. ... The global ... million by 2025. Increasing geriatric population prone to orthopedic diseases ... navigation systems over the forecast period. Osteoarthritis and osteoporosis are ...
Breaking Medicine Technology: