Protein provides link between calcium signaling in excitable and non-excitable cells

Oct 01, 2010

A calcium-sensing protein, STIM1, known to activate store-operated calcium channels has been found to also inhibit voltage-operated calcium channels, according to researchers at Temple University.

The researchers published their findings, The Calcium Store Sensor, STIM1, Reciprocally Controls Orai and Cav1.2 Channels, in the Oct. 1 issue of Science magazine.

Calcium, not just important for bones and teeth, is a universal signaling agent that is pivotal in controlling a wide range of cell functions including fast muscle and nerve responses and slower response such as cell division, cell growth, apoptosis or and even fertilization of eggs.

Calcium is stored in cells and rapidly released out and pumped back to control things like contraction of muscle or the triggering of said Donald Gill, Professor and Chair of in Temple's School of Medicine and the study's lead researcher.

He said that the STIM1 , which he helped discover about 5 years ago, was found to play a major role in sensing the low levels of calcium in cell stores and activating the highly selective Orai calcium channel to allow calcium to flow back into the cell.

"We thought it seemed crazy that the STIM1 protein goes through this incredible dance but the only thing it does is activate the Orai channel," he said. "It seemed difficult to believe it only had this one specific function."

About two years ago, Gill and his colleagues noticed that in addition to activating the Orai channel to allow calcium to trickle back into the cell stores, STIM1 was also inhibiting the function of the crucial and widespread voltage-operated calcium channel, known as the L-type—channel.

"At the time, we thought only electrically excitable cells, like cardiac, neural and skeletal cells, had L-type (or long-lasting) calcium channels," he said. "So it was surprising that the STIM1 protein known to function mostly in non-excitable cells was having a pretty profound effect on the L-type calcium channels".

"This is particularly true in tissue like smooth muscle where it is sort of like a hybrid between an excitable and a non-excitable cell, because it has the voltage-operated calcium channel and the Orai , as well as the very powerful STIM sensing system," he said.

Gill said that the researchers' finding gives a common mechanism for calcium signaling in both excitable and non-excitable cells, a link that was never before known.

"It's a very basic finding, but it's another whole area of control that people didn't know about before," he said. "They knew there were L-type calcium channels in many non-excitable , but they didn't seem to have any function. Now it seems very possible that the reason they didn't function is that the STIM1 was suppressing their function."

Explore further: Steadily rising increases in mitochondrial DNA mutations cause abrupt shifts in disease

More information: www.sciencemag.org

Related Stories

Like eavesdropping at a party

Jul 31, 2008

Cells rely on calcium as a universal means of communication. For example, a sudden rush of calcium can trigger nerve cells to convey thoughts in the brain or cause a heart cell to beat. A longstanding mystery has been how ...

Understanding night blindness and calcium

Apr 01, 2010

Congenital stationary night blindness, an inherited condition that affects one's ability to see in the dark, is caused by a mutation in a calcium channel protein that shuttles calcium into and out of cells. Now, researchers ...

Researchers reveal mechanism for neuron self-preservation

Oct 19, 2009

Tsuruta et al. find that a lipid kinase directs a voltage-gated calcium channel's degradation to save neurons from a lethal dose of overexcitement. The study appears in the October 19, 2009 issue of the Journal of ...

Epilepsy drugs could treat Alzheimer's and Parkinson's

Oct 27, 2009

Researchers in the USA have discovered a potential new function for anti-epileptic drugs in treating neurodegenerative disorders such as Alzheimer's and Parkinson's disease. The study, published in BioMed Central's open access ...

A role for calcium in taste perception

Jan 08, 2010

Calcium may not come to mind when you think of tasty foods, but in a study appearing in the January 8 issue of JBC, Japanese researchers have provided the first demonstration that calcium channels on the tongue ...

Mechanism explains calcium abnormalities in Alzheimer's brain

Jun 25, 2008

A new study uncovers a mechanism that directly links mutations that cause early onset Alzheimer's disease (AD) with aberrant calcium signaling. The research, published by Cell Press in the June 26th issue of the journal Neuron, provid ...

Recommended for you

Doctors who helped paralysed man walk seek new patients

1 hour ago

The Polish doctors who performed the revolutionary treatment that allowed a paralysed man to walk again said Wednesday they were looking for new candidates, as their patient described how the medical procedure has changed hi ...

Cause of ageing remains elusive

2 hours ago

A report by Chinese researchers in the journal Nature a few months ago was a small sensation: they appeared to have found the cause for why organisms age. An international team of scientists, headed by the ...

Newly discovered bacterial defence mechanism in the lungs

4 hours ago

A new study from Karolinska Institutet presents a previously unknown immunological mechanism that protects us against bacterial infections in the lungs. The study is being published in the American Journal of Respiratory an ...

Neutralising antibodies for safer organ transplants

Oct 21, 2014

Serious complications can arise following kidney transplants. If dialysis is required within the first seven days, then the transplanted organ is said to have a Delayed Graft Function (DGF), and essentially ...

User comments : 0