Biology subjects

Starostecka, M.

Publications and source records attributed to Starostecka, M..

2 recordsLinked to original sources

bioRxiv2021

Semaphorin 3C exacerbates liver fibrosis

Background & AimsChronic liver disease is a growing epidemic leading to fibrosis and cirrhosis. TGF-{beta} is the pivotal pro-fibrogenic cytokine which activates hepatic stellate cells (HSC), yet, other molecules can substantially modulate TGF-{beta} signaling in the course of liver fibrosis. Expression of the axon guidance molecules Semaphorins (SEMAs), which signal through Plexins and Neuropilins (NRPs), have been associated with liver fibrosis in HBV-induced chronic hepatitis. This study aims at determining their function in the regulation of HSCs. Approach & ResultsWe analyzed publicly available patient databases and liver biopsies. We employed transgenic mice where genes are deleted only in activated HSCs to perform ex vivo analysis and animal models. SEMA3C is the most enriched member of the Semaphorin family in liver samples from cirrhotic patients. Higher expression of SEMA3C in patients with NASH, alcoholic hepatitis or HBV-induced hepatitis discriminates those with a more pro-fibrotic transcriptomic profile. SEMA3C expression is also elevated in different mouse models of liver fibrosis and in isolated HSCs upon activation. In keeping with this, deletion of SEMA3C in activated HSCs reduces myofibroblast marker expression. Conversely, SEMA3C overexpression exacerbates TGF-{beta}-mediated myofibroblast activation, as shown by increased SMAD2 phosphorylation and target gene expression. Among SEMA3C receptors, only NRP2 expression is maintained upon activation of isolated HSCs. Interestingly, lack of NRP2 in those cells reduces myofibroblast marker expression. Finally, deletion of either SEMA3C or NRP2, specifically in activated HSCs, reduces liver fibrosis in mice. ConclusionSEMA3C is a novel marker for activated HSCs that plays a fundamental role in the acquisition of the myofibroblastic phenotype and liver fibrosis.

pathology↗

bioRxiv2020

Multiplexed conditional genome editing with Cas12a in Drosophila

CRISPR-Cas genome engineering has revolutionised biomedical research by enabling targeted genome modification with unprecedented ease. In the popular model organism Drosophila melanogaster gene editing has so far relied exclusively on the prototypical CRISPR nuclease Cas9. The availability of additional CRISPR systems could expand the genomic target space, offer additional modes of regulation and enable the independent manipulation of genes in different cell populations of the same animal. Here we describe a platform for efficient Cas12a gene editing in Drosophila. We show that Cas12a from Lachnospiraceae bacterium, but not Acidaminococcus spec., can mediate robust gene editing in vivo. In combination with most crRNAs, LbCas12a activity is strongly suppressed at lower temperatures, enabling control of gene editing by simply modulating temperature. LbCas12a can directly utilize compact crRNAs arrays that are substantially easier to construct than Cas9 sgRNA arrays, facilitating multiplex genome engineering of several target sites in parallel. Targeting genes with arrays of three crRNAs results in the induction of loss-of function phenotypes with comparable efficiencies than a state-of-the-art Cas9 system. Lastly, we show that cell type-specific expression of LbCas12a is sufficient to mediate tightly controlled gene editing in a variety of tissues, allowing detailed analysis of gene function in this multicellular organism. Cas12a gene editing substantially expands the genome engineering toolbox in this organism and will be a powerful method for the functional annotation of the Drosophila genome. This work also lays out principles for the development of multiplexed transgenic Cas12a genome engineering systems in other genetically tractable organisms.

genetics↗