@article {1175, title = {Stromal cells downregulate miR-23a-5p to activate protective autophagy in acute myeloid leukemia [Next Gen Genomics Facility (INT)].}, journal = {Cell Death Dis}, volume = {10}, year = {2019}, month = {2019 Sep 30}, pages = {736}, abstract = {

Complex molecular cross talk between stromal cells and the leukemic cells in bone marrow is known to contribute significantly towards drug-resistance. Here, we have identified the molecular events that lead to stromal cells mediated therapy-resistance in acute myeloid leukemia (AML). Our work demonstrates that stromal cells downregulate miR-23a-5p levels in leukemic cells to protect them from the chemotherapy induced apoptosis. Downregulation of miR-23a-5p in leukemic cells leads to upregulation of protective autophagy by targeting TLR2 expression. Further, autophagy inhibitors when used as adjuvants along with conventional drugs can improve drug sensitivity in vitro as well in vivo in a mouse model of leukemia. Our work also demonstrates that this mechanism of bone marrow stromal cell mediated regulation of miR-23a-5p levels and subsequent molecular events are relevant predominantly in myeloid leukemia. Our results illustrate the critical and dynamic role of the bone marrow microenvironment in modulating miRNA expression in leukemic cells which could contribute significantly to drug resistance and subsequent relapse, possibly through persistence of minimal residual disease in this environment.

}, issn = {2041-4889}, doi = {10.1038/s41419-019-1964-8}, author = {Ganesan, Saravanan and Palani, Hamenth Kumar and Lakshmanan, Vairavan and Balasundaram, Nithya and Alex, Ansu Abu and David, Sachin and Venkatraman, Arvind and Korula, Anu and George, Biju and Balasubramanian, Poonkuzhali and Palakodeti, Dasaradhi and Vyas, Neha and Mathews, Vikram} } @article {518, title = {Vertebrate Hedgehog is secreted on two types of extracellular vesicles with different signaling properties. (Mass spectrometry - Proteomics)}, journal = {Sci Rep}, volume = {4}, year = {2014}, month = {2014 Dec 08}, pages = {7357}, abstract = {

Hedgehog (Hh) is a secreted morphogen that elicits differentiation and patterning in developing tissues. Multiple proposed mechanisms to regulate Hh dispersion includes lipoprotein particles and exosomes. Here we report that vertebrate Sonic Hedgehog (Shh) is secreted on two types of extracellular-vesicles/exosomes, from human cell lines and primary chick notochord cells. Although largely overlapping in size as estimated from electron micrographs, the two exosomal fractions exhibited distinct protein and RNA composition. We have probed the functional properties of these vesicles using cell-based assays of Hh-elicited gene expression. Our results suggest that while both Shh-containing exo-vesicular fractions can activate an ectopic Gli-luciferase construct, only exosomes co-expressing Integrins can activate endogenous Shh target genes HNF3β and Olig2 during the differentiation of mouse ES cells to ventral neuronal progenitors. Taken together, our results demonstrate that primary vertebrate cells secrete Shh in distinct vesicular forms, and support a model where packaging of Shh along with other signaling proteins such as Integrins on exosomes modulates target gene activation. The existence of distinct classes of Shh-containing exosomes also suggests a previously unappreciated complexity for fine-tuning of Shh-mediated gradients and pattern formation.

}, keywords = {Animals, Chick Embryo, Exosomes, Extracellular Space, Hedgehog Proteins, HEK293 Cells, Humans, MicroRNAs, Models, Biological, Protein Transport, Signal Transduction, Vertebrates}, issn = {2045-2322}, doi = {10.1038/srep07357}, author = {Vyas, Neha and Walvekar, Ankita and Tate, Dhananjay and Lakshmanan, Vairavan and Bansal, Dhiru and Lo Cicero, Alessandra and Raposo, Graca and Palakodeti, Dasaradhi and Dhawan, Jyotsna} }