Bastiaans, J. | Search bioRxiv

bioRxiv2024

miR-126 modulates neural progenitor cell development

Noncoding microRNAs (miRNAs) play important roles in controlling signaling pathways by targeting multiple genes and altering their expression levels. MiR-126 is a known endothelial-specific miRNA that regulates vascular integrity and angiogenesis by enhancing proangiogenic actions of VEGF and FGF. MiR-126 is also expressed in several stem cell compartments, including embryonic stem cell (ESC) and hematopoietic stem/progenitor cells (HSPC) where it regulates cell differentiation and quiescence. Here we show that miR-126 is expressed as well in neural progenitor cells where it regulates cell differentiation by targeting genes of the IGF1R signaling pathway including IRS1, PI3K and AKT. Moreover, Hoxa9 and IGF-1 expression by neural progenitor cells is upregulated when miR-126 expression levels are reduced. Our data, implicating a role for miR-126 in manipulating cell development, could open a window of opportunities for clinical purposes and therapeutic strategies to achieve controlling neural progenitor cell behavior. HighlightsO_LIKnockdown of miR-126 in neural progenitor cells increases cell proliferation C_LIO_LImiR-126 modulates expression levels of HoxA9 and known target genes involved in the IGF1R signaling pathway in neural progenitor cells C_LIO_LIOverexpression of miR-126 results in induced cell differentiation in neural progenitor cells C_LIO_LImiR-126 affects motor neuron development in the thoracic region of the spinal cord C_LIO_LIKnockdown of miR-126 expression results in increased IGF-1 expression C_LI

cell biology↗

bioRxiv2021

SARS-CoV-2 Infects Syncytiotrophoblast and Activates Inflammatory Responses in the Placenta

SARS-CoV-2 infection during pregnancy leads to an increased risk of adverse pregnancy outcomes. Although the placenta itself can be a target of virus infection, most neonates are virus free and are born healthy or recover quickly. Here, we investigated the impact of SARS-CoV-2 infection on the placenta from a cohort of women who were infected late during pregnancy and had tested nasal swab positive for SARS-CoV-2 by qRT-PCR at delivery. SARS-CoV-2 genomic and subgenomic RNA was detected in 23 out of 54 placentas. Two placentas with high virus content were obtained from mothers who presented with severe COVID-19 and whose pregnancies resulted in adverse outcomes for the fetuses, including intrauterine fetal demise and a preterm delivered baby still in newborn intensive care. Examination of the placental samples with high virus content showed efficient SARS-CoV-2 infection, using RNA in situ hybridization to detect genomic and replicating viral RNA, and immunohistochemistry to detect SARS-CoV-2 nucleocapsid protein. Infection was restricted to syncytiotrophoblast cells that envelope the fetal chorionic villi and are in direct contact with maternal blood. The infected placentas displayed massive infiltration of maternal immune cells including macrophages into intervillous spaces, potentially contributing to inflammation of the tissue. Ex vivo infection of placental cultures with SARS-CoV-2 or with SARS-CoV-2 spike (S) protein pseudotyped lentivirus targeted mostly syncytiotrophoblast and in rare events endothelial cells. Infection was reduced by using blocking antibodies against ACE2 and against Neuropilin 1, suggesting that SARS-CoV-2 may utilize alternative receptors for entry into placental cells.

cell biology↗