Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Conditional knock-in”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

5 recordsLinked to original sources
PubMed2026

Sex-specific regulation of SLC39A11 in the murine liver.

Sex differences in health and disease are evident in humans and many other animal species. However, the sex-related determinants are less understood, and the underlying mechanisms remain elusive. By analyzing the RNA-seq data, we unexpectedly find that Slc39a11 is significantly associated with the non-alcoholic fatty liver disease pathway only in female mice, revealing a sex-specific role of Slc39a11 in liver metabolism. We then generate tissue-specific SLC39A11 knock-in and Slc39a11 knockout mice and find that female but not male SLC39A11-liver conditional overexpression (LKI) mice develop more severe cholestasis and liver injury compared to controls when fed a methionine/choline-deficient (MCD) diet. In contrast, female Slc39a11-liver conditional knockout (LKO) mice exhibit attenuated liver injury under MCD feeding. Ovariectomy in female mice largely reversed these phenotypes. Interestingly, female SLC39A11-intestine-specific overexpression (IKI) mice show alleviated liver damage, whereas female Slc39a11-intestine-specific knockout (IKO) mice develop exacerbated liver injury under MCD feeding; these effects are not observed in male SLC39A11-IKI or Slc39a11-IKO mice. This study reveals that SLC39A11 regulates liver metabolism both intrinsically and via the gut-liver axis through an evolutionarily conserved, sexual dimorphism mechanism, partially involving estrogen signaling and manganese metabolism, suggesting SLC39A11 is a potential target for the diagnosis and treatment of hepatobiliary diseases.

Animals↗
PubMed2025

Development of a new flippase-dependent mouse model for red fluorescence-based isolation of KRASG12D oncogene-expressing tumor cells.

Proto-oncogene KRAS, GTPase (KRAS) is one of the most intensively studied oncogenes in cancer research. Although several mouse models allow for regulated expression of mutant KRAS, selective isolation and analysis of transforming or tumor cells that produce the KRAS oncogene remains a challenge. In our study, we present a knock-in model of oncogenic variant KRASG12D that enables the "activation" of KRASG12D expression together with production of red fluorescent protein tdTomato. Both proteins are expressed from the endogenous Kras locus after recombination of a transcriptional stop box in the genomic DNA by the enzyme flippase (Flp). We have demonstrated the functionality of the allele termed RedRas (abbreviated KrasRR) under in vitro conditions with mouse embryonic fibroblasts and organoids and in vivo in the lung and colon epithelium. After recombination with adenoviral vectors carrying the Flp gene, the KrasRR allele itself triggers formation of lung adenomas. In the colon epithelium, it causes the progression of adenomas that are triggered by the loss of tumor suppressor adenomatous polyposis coli (APC). Importantly, cells in which recombination has successfully occurred can be visualized and isolated using the fluorescence emitted by tdTomato. Furthermore, we show that KRASG12D production enables intestinal organoid growth independent of epidermal growth factor (EGF) signaling and that the KRASG12D function is effectively suppressed by specific inhibitor MRTX1133.

Animals↗
PubMed2026

Generation and validation of a Myh11Dre-Spp1Cre intersectional mouse model for lineage tracing of disease-associated smooth muscle cell states.

BACKGROUND: Phenotypic modulation of vascular smooth muscle cells (VSMCs) is a hallmark of vascular remodeling and cardiovascular disease. Recent lineage-tracing and single-cell transcriptomic studies have identified secreted phosphoprotein 1 (SPP1) as a prominent marker associated with disease-associated VSMC states, particularly those linked to fibrotic remodeling and vascular calcification. However, the cellular origins and fate of SPP1-associated VSMC populations remain incompletely understood. METHODS AND RESULTS: We generated a novel Spp1-rSTOPr-Cre (Spp1Cre) knock-in mouse line in which Cre recombinase is expressed from the endogenous Spp1 locus following Dre-mediated excision of a rox-flanked transcriptional STOP cassette. Correct targeting of the knock-in allele was validated by internal, 5' junction, 3' junction, and long-range PCR analyses, as well as Sanger sequencing. To establish an intersectional lineage-tracing strategy, Spp1Cre mice were crossed with Myh11DreERT2 and Rosa26-RSR-LSL-tdTomato-LSL-eGFP reporter mice, enabling permanent labeling of VSMC-derived populations following activation of the endogenous Spp1 locus. Under physiological conditions, eGFP-positive cells were detected at low frequency within the vascular wall and were predominantly negative for the contractile markers ACTA2 and MYH11. As a proof-of-principle application, eGFP-positive cells markedly expanded within atherosclerotic lesions induced by AAV-PCSK9D377Y and high-fat diet feeding. These lineage-traced cells remained largely ACTA2- and MYH11-negative, consistent with a modulated phenotype. Notably, only a minority of eGFP-positive cells expressed SPP1 or fibronectin at the time of analysis, demonstrating the utility of permanent lineage tracing for tracking cells with a history of endogenous Spp1 activation during vascular remodeling. CONCLUSION: We report the generation and validation of a novel Myh11Dre-Spp1Cre intersectional mouse model for lineage tracing of VSMC-derived populations that have activated the endogenous Spp1 locus. This genetic resource provides a valuable platform for investigating the origin, fate, and phenotypic evolution of Spp1-associated VSMC populations during vascular remodeling and cardiovascular disease.

Animals↗
PubMed2026

Proteolytic activation of executioner caspase-3 and -7 regulates different physiological processes in mice.

Caspase-3 (CASP3) and caspase-7 (CASP7) are the two major executioner caspases that are proteolytically activated by upstream initiator caspases. They possess almost indistinguishable activity, which has led to the overall view that these caspases have functionally redundant roles. Here, we generate knock-in mice expressing cleavage-resistant CASP3(D175A) or CASP7(D198A). Our results show that proteolytic activation of CASP3 and CASP7 is decisive for their activity in vivo and controls redundant processes during embryonic development as combined expression of both CASP3(D175A) and CASP7(D198A) causes embryonic lethality. In adult mice, however, activation of CASP3 and CASP7 controls different processes in different tissues, without the involvement of apoptosis. While CASP7 activation is required for male fertility by controlling spermatogenesis, CASP3 activation appears crucial for lymphoid tissue development by regulating interferon signalling. Our findings shed light on emerging roles of caspases in non-apoptotic processes and provide impetus for reconsidering their involvement in physiological and pathological conditions.

Animals↗
PubMed2024

Development of SacB-based counterselection for efficient allelic exchange in Fusobacterium nucleatum.

Fusobacterium nucleatum, prevalent in the oral cavity, is significantly linked to overall human health. Our molecular comprehension of its role in oral biofilm formation and its interactions with the host under various pathological circumstances has seen considerable advancements in recent years, primarily due to the development of various genetic tools for DNA manipulation in this bacterium. Of these, counterselection-based unmarked in-frame mutation methods have proved notably effective. Under suitable growth conditions, cells carrying a counterselectable gene die, enabling efficient selection of rare, defined allelic exchange mutants. The sacB gene from Bacillus subtilis, encoding levansucrase, is a widely used counterselective marker partly due to the easy availability of sucrose. Yet, its potential application in F. nucleatum genetic study remains untested. We demonstrated that F. nucleatum cells expressing sacB in either a shuttle or suicide plasmid exhibit a lethal sensitivity to supplemental sucrose. Utilizing sucrose counterselection, we created an in-frame deletion of the F. nucleatum tonB gene, a critical gene for energy-dependent transport processes in Gram-negative bacteria, and a precise knock-in of the luciferase gene immediately following the stop codon of the hslO gene, the last gene of a five-gene operon possibly related to the natural competence of F. nucleatum. Post-counterselection with 5% sucrose, chromosomal plasmid loss occurred in all colonies, leading to gene alternations in half of the screened isolates. This sacB-based counterselection technique provides a reliable method for isolating unmarked gene mutations in wild-type F. nucleatum, enriching the toolkit for fusobacterial research.IMPORTANCEInvestigations into Fusobacterium nucleatum's role in related diseases significantly benefit from the strategies of creating unmarked gene mutations, which hinge on using a counterselective marker. Previously, the galk-based allelic exchange method, although effective, faced an inherent limitation-the need for a modified host. This study aims to surmount this limitation by substituting galK with sacB for gene modification in F. nucleatum. Our application of the sacB-based methodology successfully yielded a tonB in-frame deletion mutant and a luciferase gene knock-in at the precise chromosomal location in the wild-type background. The new method augments the existing toolkit for F. nucleatum research and has far-reaching implications due to the easy accessibility to the counterselection compound sucrose. We anticipate its broader adoption in further exploration, thereby reinforcing its critical role in propelling our understanding of F. nucleatum.

Fusobacterium nucleatum↗