autophagosomes Archives - Sanford Burnham Prebys
Institute News

Top Sanford Burnham Prebys research stories of 2021

AuthorSusan Gammon
Date

December 14, 2021

This year’s most popular research stories include scientific breakthroughs in COVID-19, cancer, schizophrenia and more.

As we bid farewell to 2021, let’s celebrate our most newsworthy research breakthroughs. Despite the continuing challenges brought on by COVID-19, Sanford Burnham Prebys achieved important milestones on the frontiers of biomedical science.

The following 10 research-related stories received top views on Newswise—the press release distribution service for journalists seeking health and science news.

  1. COVID-19: Scientists identify human genes that fight infection
    A research team was able to pinpoint specific human genes that control viral infection. The information sheds new light on factors that lead to severe disease and guides therapeutic options.
  2. Tumor marker may help overcome endocrine treatment-resistant breast cancer
    The study discovered a new approach to select breast cancer patients for HER2 therapy and could help individuals avoid disease relapse or progression of endocrine-sensitive disease.
  3. Scientists identify potential drug candidates for deadly pediatric leukemia
    Two existing drugs—JAK inhibitors and Mepron—show promise for a subtype of acute myeloid leukemia (AML) that is more common in children. The drugs are proven safe in humans, which could accelerate clinical studies.
  4. Leprosy drug holds promise as at-home treatment for COVID-19
    Scientists found that the leprosy drug clofazimine, which is FDA approved and on the World Health Organization’s List of Essential Medicines, exhibits potent antiviral activities against SARS-CoV-2, and could become an important weapon against future pandemics.
  5. Researchers dig deeper into how cells transport their waste for recycling
    Research describing how the “trash bags” in a cell—called autophagosomes—are tagged for recycling opened new paths to understand age-related diseases such as cancer and neurological disorders. 
  6. New drug combination shows promise as powerful treatment for AML
    Researchers identified two drugs that are potent against acute myeloid leukemia (AML) when combined, but only weakly effective when used alone. The study provides a scientific rationale for advancing clinical studies of the drug combination. 
  7. Biomarker could help diagnose schizophrenia at an early age
    A study described how elevated levels of a protein called CRMP2—found in the brain and blood—could become a format for a rapid, minimally invasive blood test to support the diagnosis of schizophrenia.
  8. Scientists identify “immune cop” that detects SARS-CoV-2
    Researchers discovered the sensor in human lungs that detects SARS-CoV-2 and signals that it’s time to mount an antiviral attack. The sensor activates interferon, the body’s own frontline defender against viral invasion.
  9. Study finds promising therapeutic target for colitis
    Scientists identified an enzyme in the gut that triggers an inflammatory cascade leading to colitis. Therapeutically targeting the enzyme may be a viable approach to help the millions of people worldwide affected by the disorder.
  10. Scientists shrink pancreatic tumors by starving their cellular “neighbors”
    For the first time, blocking “cell drinking,” or micropinocytosis in the thick tissue surrounding a pancreatic tumor, was shown to slow tumor growth—providing more evidence that micropinocytosis is an important therapeutic target.
Institute News

Newly discovered cell stress pathway could hold therapeutic promise for diverse diseases

AuthorGuest Blogger
Date

January 5, 2015

This post was written by Janelle Weaver, PhD, a freelance writer.

When cells are faced with unfavorable environmental conditions, such as limited nutrient availability, the activation of adaptive stress responses can help protect them against damage or death. For example, stressed cells can maintain sufficient energy levels for survival by degrading and recycling unnecessary or dysfunctional cellular components. This survival mechanism, known as autophagy (literally, ‘self-digestion’), also plays key roles in a variety of biological processes such as development and aging, and is often perturbed in various diseases. Even though tight control of autophagy is key to survival, relatively little is known about the signaling molecules that regulate this essential process.

Sanford-Burnham researchers have made important progress in addressing this gap in knowledge by discovering that proteins called STK3 and STK4 regulate autophagy across diverse species. As reported recently in Molecular Cell, the newly identified mode of autophagy regulation could potentially have important clinical implications for the treatment of a broad range of diseases, including cancer, diabetes, Alzheimer’s disease, cardiac dysfunction, and immune-related diseases.

“Our discovery is fundamental to our molecular understanding of how autophagy is regulated,” said senior study author Malene Hansen, PhD, associate professor of the Development, Aging, and Regeneration Program at Sanford-Burnham. “Because impairment in the autophagy process has been linked to many disorders in humans, we believe that pharmacological agents targeting this novel regulatory circuit may hold great therapeutic potential.”

Critical kinases

Autophagy is a cellular recycling process involving a highly intricate and complex series of events. Cellular components such as abnormal molecules or damaged organelles are first sequestered within vesicles known as autophagosomes. These vesicles then fuse with organelles called lysosomes, which contain enzymes that break down various molecules. This fusion process results in the formation of hybrid organelles called autolysosomes, where the defective cellular components are enzymatically degraded and recycled. A protein called LC3 plays crucial roles in the formation of autophagosomes and the recruitment of dysfunctional cellular components to these vesicles. The signaling events that coordinate LC3’s various functions in autophagy have not been clear, but new research from the Hansen lab now proposes a novel and essential role for the mammalian Hippo kinases STK3 and STK4 in regulating autophagy by targeting LC3 for phosphorylation.

In their study, Hansen and her team describe that deficiency in both STK3 and STK4 impairs autophagy not just in mammalian cells, but also in nematodes and yeast. When exploring how the kinases regulate autophagy in mammalian cells, the researchers discovered that phosphorylation of LC3 by STK3 and STK4, specifically on the amino acid threonine 50, is critical for fusion between autophagosomes and lysosomes—an essential step in the autophagy process. “Collectively, the results of this study strongly support a critical and evolutionarily conserved role for STK3 and STK4 in regulating autophagy, by phosphorylating the key autophagy protein LC3, at least in mammalian cells,” Hansen said.

Killing bacteria

Previous studies have shown that STK4 also plays a role in regulating antibacterial and antiviral immunity in mammals, including humans. Moreover, autophagy is known to play a role in the clearance of intracellular pathogens. “These findings, taken together with our discovery that deficiency in STK3 and STK4 severely compromises autophagy, led us to test whether STK4 also plays a role in antimicrobial immunity through its function in autophagy,” said lead study author Deepti Wilkinson, Ph.D., a postdoctoral fellow in Hansen’s lab.

To test this notion, the researchers collaborated with Victor Nizet MD, professor of Pediatrics and Pharmacy  at UC San Diego and found that indeed mouse embryonic cells deficient in both STK3 and STK4 were unable to efficiently kill intracellular group A streptococci—bacteria known to be cleared by autophagy. However, an LC3 mutation that resulted in constant phosphorylation at threonine 50 restored the ability of the STK3/STK4-deficient cells to kill the bacteria. “This finding suggests that the same STK4-LC3 signaling pathway involved in autophagy also contributes to the response of mammalian cells to infection with intracellular pathogens and could play a role in human immune-related disease,” Wilkinson said.

Correcting defects

Moving forward, the researchers plan to further probe the molecular mechanisms by which STK3 and STK4 regulate autophagy. They will also investigate the therapeutic implications of the STK3/STK4 signaling pathway for tumor suppression as well as immune-related disorders such as bacterial and viral infections. “Understanding how autophagy works and why it sometimes stops to function optimally is essential for fighting diseases such as cancer, diabetes and neurodegeneration,” Hansen said.

“We have made a major contribution towards this endeavor by showing that STK3 and STK4 play an essential role in keeping the process of autophagy running smoothly by directly phosphorylating the key autophagy protein LC3. We hope our discoveries will lead to the development of effective drugs that can help correct autophagy defects that commonly occur in these diseases,” added Hansen.

A copy of the paper can be found at: http://www.ncbi.nlm.nih.gov/pubmed/25544559