Drosophila mind bomb2 is required for maintaining muscle integrity and survival

We report that the Drosophila mind bomb2 (mib2) gene is a novel regulator of muscle development. Unlike its paralogue, mib1, zygotic expression of mib2 is restricted to somatic and visceral muscle progenitors, and their respective differentiated musculatures. We demonstrate that in embryos that lack functional Mib2, muscle detachment is observed beginning in mid stage 15 and progresses rapidly, culminating in catastrophic degeneration and loss of most somatic muscles by stage 17. Notably, the degenerating muscles are positive for apoptosis markers, and inhibition of apoptosis in muscles prevents to a significant degree the muscle defects. Rescue experiments with Mib1 and Neuralized show further that these E3 ubiquitin ligases are not capable of ameliorating the muscle mutant phenotype of mib2. Our data suggest strongly that mib2 is involved in a novel Notch- and integrin-independent pathway that maintains the integrity of fully differentiated muscles and prevents their apoptotic degeneration

Targeted cell delivery of mesenchymal stem cell therapy for cardiovascular disease applications: a review of preclinical advancements

Cardiovascular diseases (CVD) continue to be the leading cause of morbidity and mortality globally and claim the lives of over 17 million people annually. Current management of CVD includes risk factor modification and preventative strategies including dietary and lifestyle changes, smoking cessation, medical management of hypertension and cholesterol lipid levels, and even surgical revascularization procedures if needed. Although these strategies have shown therapeutic efficacy in reducing major adverse cardiovascular events such as heart attack, stroke, symptoms of chronic limb-threatening ischemia (CLTI), and major limb amputation significant compliance by patients and caregivers is required and off-target effects from systemic medications can still result in organ dysfunction. Stem cell therapy holds major potential for CVD applications but is limited by the low quantities of cells that are able to traffic to and engraft at diseased tissue sites. New preclinical investigations have been undertaken to modify mesenchymal stem cells (MSCs) to achieve targeted cell delivery after systemic administration. Although previous reviews have focused broadly on the modification of MSCs for numerous local or intracoronary administration strategies, here we review recent preclinical advances related to overcoming challenges imposed by the high velocity and dynamic flow of the circulatory system to specifically deliver MSCs to ischemic cardiac and peripheral tissue sites. Many of these technologies can also be applied for the targeted delivery of other types of therapeutic cells for treating various diseases

Loss of L3MBTL1, a Candidate 20q12 Tumor Suppressor Gene, Leads to DNA Damage

Abstract Abstract 1974 Poster Board I-997 The L3MBTL1 gene is located on the long arm of chromosome 20 (q12), a region commonly lost in several myeloid malignancies, including myeloproliferative diseases (MPD), myeloprodysplastic disorders (MDS), and acute myeloid leukemias (AML). MDS and AML frequently have complex cytogenetic profiles, and are thought to arise due to accumulation of several cooperating mutations. We have previously reported that L3MBTL1 is highly expressed in human hematopoietic progenitor cells. L3MBTL1 is a homolog of Drosophila polycomb L3MBTL tumor suppressor protein. Thus, L3MBTL1 is a candidate gene in 20q12 myeloid disorders. We have depleted L3MBTL1 by RNAi in several human cell lines, and find that loss of L3MBTL1 leads to a decrease of cells in the S phase of the cell cycle and accumulation in G2/M phase. Cells with depleted L3MBTL1 have an increase of spontaneous DNA breaks, as evidenced by accumulation of γH2A.X foci and comet assay. The presence of DNA breaks leads to activation of DNA damage response, as the L3MBTL1 knockdown cells have increased levels of phosphoChk1 (Ser317 and Ser345), phosphoChk2 (Thr68), phosphoATM (Ser1981), p21 and p53. The DNA damage in the L3MBTL1-depleted cells activates DNA repair machinery, as shown by the increase in Rad51 levels. We propose that the spontaneous DNA damage caused by depletion of L3MBTL1 could contribute to the development of 20q12 myeloid malignancies. Disclosures: No relevant conflicts of interest to declare

Mesenchymal stem cell-based therapy for non-healing wounds due to chronic limb-threatening ischemia: A review of preclinical and clinical studies

Progressive peripheral arterial disease (PAD) can result in chronic limb-threatening ischemia (CLTI) characterized by clinical complications including rest pain, gangrene and tissue loss. These complications can propagate even more precipitously in the setting of common concomitant diseases in patients with CLTI such as diabetes mellitus (DM). CLTI ulcers are cutaneous, non-healing wounds that persist due to the reduced perfusion and dysfunctional neovascularization associated with severe PAD. Existing therapies for CLTI are primarily limited to anatomic revascularization and medical management of contributing factors such as atherosclerosis and glycemic control. However, many patients fail these treatment strategies and are considered "no-option," thereby requiring extremity amputation, particularly if non-healing wounds become infected or fulminant gangrene develops. Given the high economic burden imposed on patients, decreased quality of life, and poor survival of no-option CLTI patients, regenerative therapies aimed at neovascularization to improve wound healing and limb salvage hold significant promise. Cell-based therapy, specifically utilizing mesenchymal stem/stromal cells (MSCs), is one such regenerative strategy to stimulate therapeutic angiogenesis and tissue regeneration. Although previous reviews have focused primarily on revascularization outcomes after MSC treatments of CLTI with less attention given to their effects on wound healing, here we review advances in pre-clinical and clinical studies related to specific effects of MSC-based therapeutics upon ischemic non-healing wounds associated with CLTI

Targeted cell delivery of mesenchymal stem cell therapy for cardiovascular disease applications: a review of preclinical advancements

Cardiovascular diseases (CVD) continue to be the leading cause of morbidity and mortality globally and claim the lives of over 17 million people annually. Current management of CVD includes risk factor modification and preventative strategies including dietary and lifestyle changes, smoking cessation, medical management of hypertension and cholesterol lipid levels, and even surgical revascularization procedures if needed. Although these strategies have shown therapeutic efficacy in reducing major adverse cardiovascular events such as heart attack, stroke, symptoms of chronic limb-threatening ischemia (CLTI), and major limb amputation significant compliance by patients and caregivers is required and off-target effects from systemic medications can still result in organ dysfunction. Stem cell therapy holds major potential for CVD applications but is limited by the low quantities of cells that are able to traffic to and engraft at diseased tissue sites. New preclinical investigations have been undertaken to modify mesenchymal stem cells (MSCs) to achieve targeted cell delivery after systemic administration. Although previous reviews have focused broadly on the modification of MSCs for numerous local or intracoronary administration strategies, here we review recent preclinical advances related to overcoming challenges imposed by the high velocity and dynamic flow of the circulatory system to specifically deliver MSCs to ischemic cardiac and peripheral tissue sites. Many of these technologies can also be applied for the targeted delivery of other types of therapeutic cells for treating various diseases

L3MBTL1 polycomb protein, a candidate tumor suppressor in del(20q12) myeloid disorders, is essential for genome stability

The l3mbtl1 gene is located on the long arm of chromosome 20 (q12), within a region commonly deleted in several myeloid malignancies. L3MBTL1 is a human homolog of the Drosophila polycomb L(3)MBT tumor suppressor protein and thus a candidate tumor suppressor in del(20q12) myeloid disorders. We used the loss-of-function approach to explore the possible tumor suppressive mechanism of L3MBTL1 and found that depletion of L3MBTL1 from human cells causes replicative stress, DNA breaks, activation of the DNA damage response, and genomic instability. L3MBTL1 interacts with Cdc45, MCM2-7 and PCNA, components of the DNA replication machinery, and is required for normal replication fork progression, suggesting that L3MBTL1 causes DNA damage, at least in part, by perturbing DNA replication. An activated DNA damage response and genomic instability are common features in tumorigenesis and a consequence of overexpression of many oncogenes. We propose that the loss of L3MBTL1 contributes to the development of 20q − hematopoietic malignancies by inducing replicative stress, DNA damage, and genomic instability