Syndicate content

Archive - Jul 1, 2020

Date

Solving the CNL6 Mystery in Batten Disease: CLN6 and CLN8 Interact with Each Other, Forming Molecular Complex That Collects Lysosomal Enzymes at Endoplasmic Reticulum and Mediates Their Trafficking Towards Lysosomes

Batten disease is a family of 13 rare, genetically distinct conditions. Collectively, they are the most prevalent cause of neurodegenerative disease in children, affecting 1 in 12,500 live births in the U.S. One of the Batten disease genes is CLN6. How mutations in this gene lead to the disease has been a mystery, but a study, led by researchers at Baylor College of Medicine and published online on June 29, 2020, in the Journal of Clinical Investigation (https://www.jci.org/articles/view/130955), reveals how defective CLN6 can result in Batten disease. The open-access article is titled “A CLN6-CLN8 Complex Recruits Lysosomal Enzymes at the ER for Golgi Transfer.” “People with Batten disease have problems with their cells' ability to clear cellular waste, which then accumulates to toxic levels," said first author Lakshya Bajaj (http://www.sardiellolab.com/lakshya-bajaj.html), DDS/PhD, who was working on this project while a doctorate student in the laboratory of Marco Sardiello (https://www.bcm.edu/research/baylor-research/faculty-recognition/debakey...), PhD, at Baylor. Dr. Bajaj is currently a post-doctoral associate at Harvard Medical School (https://www.linkedin.com/in/lakshya-bajaj-3637661a/). In cells, lysosomes process cellular waste. They are sacs containing enzymes, a type of proteins that break down waste products into its constituent components that the cell can recycle or discard. In Batten disease caused by mutations in CLN6 (ceroid lipofuscinosis, neuronal 6), the lysosomes do not process waste effectively for unknown reasons. This results in waste accumulation. Batten disease is a type of lysosomal storage disorder.

New Study from Cedars-Sinai Shows That SARS-CoV-2 Can Infect Heart Cells in Vitro; Results Suggest Possibility That SARS-CoV-2 Can Directly Infect Heart Cells in COVID-19 Patients

A new study shows that SARS-CoV-2, the virus that causes COVID-19 (coronavirus 2019), can infect heart cells in a lab dish, indicating it may be possible for heart cells in COVID-19 patients to be directly infected by the virus. The discovery, published online on June 25, 2020 in Cell Reports Medicine (https://www.cell.com/cell-reports-medicine/fulltext/S2666-3791(20)30068-9) (see graphic abstract of article below), was made using heart muscle cells that were produced by stem cell technology. The article is titled “Human iPSC-Derived Cardiomyocytes, Are Susceptible to SARS-CoV-2 Infection.” Although many COVID-19 patients experience heart problems, the reasons are not entirely clear. Pre-existing cardiac conditions or inflammation and oxygen deprivation that result from the infection have all been implicated. But, until now, there has been only limited evidence that the SARS-CoV-2 virus directly infects the individual muscle cells of the heart. “We not only uncovered that these stem cell-derived heart cells are susceptible to infection by novel coronavirus, but that the virus can also quickly divide within the heart muscle cells,” said Arun Sharma, PhD, a Senior Research Fellow at the Cedars-Sinai Board of Governors Regenerative Medicine Institute and the first and co-corresponding author of the study. “Even more significant, the infected heart cells showed changes in their ability to beat after 72 hours of infection.” The study also demonstrated that human stem-cell-derived heart cells infected by SARS-CoV-2 change their gene expression profile, further confirming that the cells can be actively infected by the virus and activate innate cellular “defense mechanisms” in an effort to help clear out the virus.

Novel Function for Platelets: Nucleus-Free Cell Fragments Can Reduce Metastasis by Helping Preserve Vascular Barrier, Making Blood-Vessel Wall Selectively Impermeable, Thereby Reducing Spread of Tumor Cells to Other Parts of Body

Scientists at Uppsala University in Sweden have discovered a hitherto unknown function of blood platelets in cancer. In mouse models, these platelets have proved to help preserve the vascular barrier which makes blood-vessel walls selectively impermeable, thereby reducing the spread of tumor cells to other parts of the body. The study results were published online on June 25, 2020 in Cancer Research. The article is titled “Platelet-Specific PDGFB Ablation Impairs Tumor Vessel Integrity and Promotes Metastasis.” Platelets (https://en.wikipedia.org/wiki/Platelet), also known as thrombocytes, are tiny cell fragments, without a nucleus, that form in the bone marrow and circulate in the blood. If we are injured and start bleeding, platelets clump together, sealing off the wound while also helping the blood to coagulate. When the platelets are activated--which occurs not only in wounds, but also in tumors--the substances known as growth factors contained in the platelets are released into their immediate surroundings. One of these growth factors is platelet-derived growth factor B (PDGFB). In the Uppsala study, the researchers investigated what happens when the PDGFB in platelets, but not in other cell types, is deleted in individuals with cancer. PDGFB from platelets was found to be essential, to attract supporting cells to the tumor blood vessels. In healthy tissue, on the other hand, the platelets did not to perform this function. If PDGFB was lacking in platelets, the quantity of circulating tumor cells increased and they spread to other parts of the body to a much higher degree. Previous studies have shown that PDGFB from cells of another kind, endothelial cells that line the inside of blood vessels, is necessary to attract supporting cells to the vessels when they form.