Tag Archives: epigenetics

Inside the Pancreas: How Beta Cells Change as We Age

[A diabetic supply kit, complete with a knitted pouch that’s shaped like a pancreas. Photo by Erin Stevenson O’Connor via Flickr and Creative Commons.] 

The box arrived around 5:00 pm. Many of Efsun Arda’s colleagues were already heading home for Thanksgiving, but Arda had work to do. As a post-doc in Seung Kim’s lab at Stanford, Arda studies one of the body’s most unknowable vital organs– the pancreas.

Although the pancreas plays a crucial role in diabetes–which impacts almost 1 in 10 Americans, according to the CDC–and although pancreatic cancer is extremely lethal, the pancreas remains largely a mystery, Kim and Arda say.

(A quick Google Scholar search turned up 20,500 papers mentioning the pancreas in 2016 so far, but that’s a stark contrast to the 124,000 papers for “liver” and 113,000 for “kidney”.) 

Much of what doctors do know about the pancreas comes from inference based on physiological and blood chemistry studies.

Collecting pancreas samples from living people is extremely risky and highly impractical. The pancreas itself is a large gland, full of active enzymes, nestled in a tough-to-reach spot behind the stomach. The enzymes inside the pancreas itself are “like a pack of wolves” Kim says; the slightest damage will cause the organ to start digesting itself, which would likely kill the patient.

Consequently, most studies that peek under the pancreas’ hood rely on cadavers.  Continue reading “Inside the Pancreas: How Beta Cells Change as We Age” »

5 Amazing Feats Performed by “Meta-Genes”

[Image via the NIH Image Gallery. Photo by Alex Ritter, Jennifer Lippincott Schwartz, and Gillian Griffiths. Full video, complete with narration here.] 

Under the Radar: A series of listicles about biology concepts you definitely won’t find in newspaper headlines.

#1: Be a Navigation App for Immune Cells

Natural killer cells, or “NK cells” are the human body’s best defense against cancer.  While other types of immune cells often ignore tumor cells, natural killer cells specialize in finding and destroying human cells that look either infected or like cancer mutants. In leukemia patients,  a higher number of active natural killer cells ups the patient’s chances for survival, so much so that  researchers are experimenting with transfusing NK cells into patients.

Just one problem there: Active natural killer cells die without a strong support network.

Dormant NK cells can survive in the bloodstream for a long time, but once activated, natural killers have to make a b-line for cells carrying a marker called IL-15 or die,  but until a study in Monday’s edtion of PNAS , no one knew how natural killers knew to look for IL-15. The study, led by Vanderbilt immunologist Eric Sebzda and grad student Whitney Rabacal, traced NK cells’ IL-15 homing ability back to a biochemical with the horrendous name “Kruppel-like Factor 2” (KLF2).

KLF2, oddly enough, also exerts a strong navigational influence on the immune system’s T-cells and B-cells.  Even though all three types of cells fall under the “white blood cell” umbrella, the notion that one protein could control navigation in all three is pretty weird.  Crawling and navigating are complex tasks, requiring coordination between dozens of genes. “[NK cell migration] is totally different from how t-cells and b-cells circulate,” Sebzda said.

Additionally, taking away KLF2 has distinctive effects on each type of cell: KLF2-less t-cells vacate the central body and crawl out to lab mice’s fingers and toes, KLF2-less b-cells all congregate at the spleen (which creates some serious problems for those lab mice), and KLF2-less natural killers end up dying alone.

So KLF2 could be super-useful for improving cancer immunotherapy. But why is KLF2 so versatile in the first place?

The answer lies in KLF2’s ability to bind to a certain recurring DNA base pair sequence, one that presumably earmarks the genes needed in each immune system navigation system, and it’s far from the only protein with such abilities…

Continue reading “5 Amazing Feats Performed by “Meta-Genes”” »