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[Tissue-specific inhibition of DNA synthesis by contactins, factors that possess tissue-specific adhesive activity].

Highly purified factors extracted from the liver and lungs of adult rats, tissue-specifically increasing the stability of intercellular contacts and of cell plasma membranes to mechanical disruption, were found to decrease, in the same manner, the labeling index (LI) in explants of the embryonic tissue of mice. The comparison of the action of these factors on the LI, and on mechanical properties of the tissue has shown that the latter effect is manifested earlier than the former one.

Adhesiveness

Changes in the transcriptome and synthetic lethal dependencies following KRAS mutant expression reveal profound tissue specificity.

Oncogenic KRAS mutations exhibit a striking tissue-restricted tropism, occurring with high frequency in pancreatic, colorectal, and lung adenocarcinomas while remaining rare in other lineages. The molecular basis for why these specific tissues are uniquely permissive to KRAS transformation, and how this context shapes therapeutic vulnerabilities, remains poorly defined. Here, we utilized CRISPR-mediated genome engineering to generate endogenous, conditional KRAS-mutant isogenic cell line models across three primary permissive lineages (lung, colon, and pancreas) and the nonpermissive breast lineage. Integrated genome-wide CRISPR fitness screens and comparative transcriptome analyses revealed that KRAS-driven synthetic lethal (SL) dependencies are profoundly shaped by their tissue of origin. Strikingly, we observed minimal overlap in SL hits across lineages, with only three genes shared among the permissive lines, suggesting that the KRAS oncogene operates through divergent, context-specific genetic networks. Mechanistically, we show that KRAS activation induces a universal MYC-driven metabolic signature, but the specific machinery required to sustain this state is lineage-restricted. We identified a dependency on the diphthamide synthesis pathway to maintain translational fidelity amid a KRAS-induced hypertranslational state. These findings demonstrate that even when driven by the same oncogene, tumors exhibit distinct regulatory landscapes and unique genetic vulnerabilities. Our results provide a framework for developing lineage-aware therapeutic strategies, moving beyond universal KRAS inhibition toward targeted interventions tailored to a tumor's specific tissue context.

Proto-Oncogene Proteins p21(ras)

Predictive design of tissue-specific mammalian enhancers that function in the mouse embryo.

Enhancers control tissue-specific gene expression across animals1. Although deep learning2,3 has enabled enhancer prediction and design in mammalian cell lines and non-mammalian model organisms4-10 (reviewed in a previous publication11), it remains unclear whether such approaches can operate within the regulatory complexity of mammalian genomes and tissues in vivo. Here we present a general strategy for designing tissue-specific enhancers that function reliably in mice. We use deep learning to train compact convolutional neural networks on curated chromatin accessibility data and fine-tune them by transfer learning on validated human and mouse enhancers. Guided by these models, we design 15 synthetic enhancers for the heart, limb and central nervous system in mouse embryos, all of which are active in their intended target tissue. These results demonstrate that mammalian enhancer function can be reliably inferred from DNA sequence alone, enabling the predictive de novo design of tissue-specific synthetic enhancers from modest training sets. This work establishes a generalizable framework for programmable control of mammalian gene expression in vivo, opening new avenues in functional genomics, synthetic biology and gene therapy.

Animals

Conversion of human erythrocyte-adenosine deaminase activity to different tissue-specific isozymes. Evidence for a common catalytic unit.

Adenosine deaminase activity resides in various characteristic isozymes in red blood cells (RBC-ADA) and other tissues. Absence of RBC-ADA has been reported in a proportion of patients with autosomally inherited severe combined immunodeficiency (SCID). We have previously reported that the tissue isozymes of ADA are also deficient in children with SCID and RBC-ADA deficiency, although these isozymes differ from RBC-ADA in molecular weight, accessible SH groups, and electrophoretic mobility. The deficiency of all types of ADA in SCID implies that a catalytic unit of ADA in each isozyme is coded by the same structural gene. The relationship of RBC-ADA and the different tissue ADA isozymes is the subject of this paper. Incubation of RBC-ADA with ADA-deficient liver, kidney, and fibroblast extracts resulted in the appearance of new isozymes of ADA. These newly generated isozymes had the physicochemical and electrophoretic characteristics of the tissue-specific isozymes obtained from normal tissues. The electrophoretic mobility of the isozyme generated appeared to depend upon the tissue utilized and corresponded to the electrophoretic mobilities of the ADA isozymes found naturally in each of the different tissues. Additionally, the genetically determined polymorphism exhibited by RBC-ADA could be detected in the isozyme generated. Incubation with normal kidney also caused conversion of the RBC isozyme to the kidney form. These findings further support the concept that the catalytic activity of each of the several forms of the ADA enzyme resides in a single molecule coded at the same genetic locus as is defective in one form of SCID. The tissue-specific isozymes, which differ in electrophoretic mobility and molecular weight, are generated by interaction of the RBC catalytic unit with tissue-specific factors present in the different tissues of normal humans and patients.

Aminohydrolases

[Tissue specific uncoupler of mitochondrial oxidative phosphorylation].

The influence of endogenous uncoupling agent from the rat liver on oxidative phosphorylation of the liver, kidney, heart, lungs, and brain mitochondria was studied; the tissue-specificity of its action was demonstrated. The selective action of the uncoupler on the mitochondrial membrane is more obviously expressed within the range of pH 6.9--6.3 approaching such of the hepatocyte cytoplasm. The tissue-specificity was independent of the original state of mitochondria and could be eliminated only by heat injury of the oxidative phosphorylation. The activity of the tissue-specific uncoupling factor failed to diminish when the ribosomes and microsomes were removed by centrifugation. Addition of bovine albumin to the incubation medium had no influence of the value of the tissue-specific uncoupling. Participation of the uncoupler in the intratissue proliferation control is discussed.

Animals

Infection of developing mouse embryos with murine leukemia virus: tissue specificity and genetic transmission of the virus.

The tissue specificity of Moloney leukemia virus (M-MuLV) was studied by infecting mice at two different stages of development. Either newborn mice which can be considered as essentially fully differentiated animals were infected with M-MuLV or preimplantation mouse embryos were infected in vitro at the 4-8 cell stage, a stage of development before any differentiation has taken place. After surgical transfer to the uteri of pseudopregnant surrogate mothers, the latter developed to term and adult mice. In both cases, animals were obtained that had developed an M-MuLV induced leukemia. Molecular hybridization tests for the presence of M-MuLV-specific sequences were conducted on DNA extracted from different tissues of leukemic animals to determine which tissues were successfully infected by the virus. Mice which were infected as newborns carried M-MuLV-specific DNA sequences in "target tissues" only, i. e., thymus, spleen, lymph nodes or in organs infiltrated by tumor cells, whereas "non-target tissues" did not carry virus-specific sequences. In contrast, when leukemic animals derived from M-MuLV-infected preimplantation embryos were analyzed, virus-specific sequences were detected in target tissues as well as in non-target tissues, such as liver, kidney, brain, testes and the germ line. To study the expression of the viral DNA integrated in target and non-target organs, RNA was extracted from different tissues of an animal infected at the preimplantation stage. Fifty to 100 times more M-MuLV-specific RNA was detected in tumor tissues than was found in non-target organs. Since all organs contained the same amount of virus-specific DNA, these results indicate that the integrated virus genome can be differentially expressed in different tissues. The organ-tropism of RNA tumor viruses is discussed in view of these findings. Mice that were infected at the preimplantation stage were found to have M-MuLV integrated into their germ line. Virus transmission from the father to the offspring occurred according to simple Mendelian expectations. Molecular hybridization tests revealed that in the animals studied, the virus was integrated into the germ line at only one out of two or three possible integration sites. During the development of leukemia amplification of this virus copy was observed in the target tissues only, but not in the non-target tissues.

Animals

Tissue-specific DNA-protein complexes during azo dye hepatocarcinogenesis.

The immunological tissue specificity could be transferred from one chromatin preparation to another by reconstituting this protein fraction to the DNA and the remaining chromatin components."The immunological tissue specificity could be transferred from one chromatin preparation to another by reconstituting this protein fraction this protein fraction to the DNA and the remaining chromatin components.

Alpha-Globulins

Population genetics of Drosophila amylase. I. Genetic control of tissue-specific expression in D. pseudoobscura.

Drosophila pseudoobscura is polymorphic for tissue-specific expression of alpha-amylase in adult midguts. This enzyme is encoded by a single locus, Amy, on the third chromosome. In this paper we show: (1) Up to about 12 days post-eclosion, the midgut activity patterns remain stable; after 12 days areas not showing activity previously begin to show activity. Thus, the genes controlling the expression of Amy are temporally acting. (2) Diet affects the quantitative, but not the qualitative, expression of Amy. (3) The expression of Amy in adult midguts is under genetic control. Selection for different frequencies of patterns is possible; realized heritabilities are 0.20 to 0.50. Partial linkage with third chromosome inversions has been demonstrated; the genes or elements controlling Amy expression are not, however, confined to the third chromosome. (4) The genetic elements controlling tissue-specific expression of amylase do not coordinately control the expression of five other "digestive-type" enzymes that were studied.--This polymorphism appears to be analogous to that studied by Abraham and Doane (1978) in D. melanogaster, wherein they have mapped regulatory genes.

Amylases

The tissue-specific effects of glucose-lowering drug targets on aging mediated through DNA methylation: a multi-omics genetic study.

BACKGROUND: DNA methylation plays a key role in mediating the anti-aging effects of glucose-lowering drugs. This study aims to systematically explore the potential anti-aging effects of target genes of FDA-approved glucose-lowering drugs and the underlying epigenetic mediators. METHODS: We conducted a two-sample Mendelian randomization (MR) study to investigate the putative causal relationships between the gene expression levels of glucose-lowering drug targets and 10 aging-related phenotypes, followed by a two-step MR to estimate the mediation effect of DNA methylation. Drug candidates were selected according to the latest review of clinical drug use for type 2 diabetes, and their target genes were obtained from the DGIdb. Tissue-specific cis-expression quantitative trait loci (eQTLs) from GTEx Consortium were selected as genetic instruments to proxy the expression level of drug-target genes. Glycemic phenotypes were used as positive controls to validate the instruments. The cis- and trans-methylation QTLs of Cytosine-phosphate-Guanine sites near the drug target genes were obtained from GoDMC Consortium. Additionally, we performed enrichment analyses focused on tissue specificity and aging pathways to further corroborate our findings. RESULTS: We obtained 194 target genes interacting with 36 FDA-approved anti-diabetic drugs, of which the tissue-specific eQTLs were used to proxy the drug target effects. MR showed strong evidence that nine interacting genes of six glucose-lowering drugs showed anti-aging potential on one or more aging-related phenotypes mediated by DNA methylation: EHMT2, HSPA4, IGF2BP2, IRS1, LPL, NDUFAF1, NDUFS3, SLC22A3, and TCF7L2. These genes were distributed in 17 tissues, especially in the central nervous system, suggesting a potential neural component in their anti-aging effects. For instance, expression of EHMT2 in several brain basal ganglia regions, where the gene interacted with Tolazamide, showed a protective effect on frailty (odds ratio (OR) in caudate = 1.02, 95%CI = 1.01-1.04, FDR adjusted P = 1.69 × 10-2; OR in putamen = 1.02, 95% CI = 1.01-1.03, PFDR = 3.37 × 10-2, OR in nucleus accumbens = 1.02, 95% CI = 1.01-1.04, PFDR = 3.37 × 10-2). These associations were externally validated by searching literature evidence in existing EWAS and TWAS studies, as well as evidence from enrichment analyses. CONCLUSIONS: This study prioritizes nine glucose-lowering genes as anti-aging drug targets in specific tissues and prioritizes their epigenetic regulation through DNA methylation for future drug development.

DNA Methylation

Identification of tissue-specific antigens and concanavalin A receptors on rat epidermal cells using a radio-immunoprecipitation method.

Iodination with lactoperoxidase - 125I- - H2O2 was used to label surface components of rat epidermal cells. Lysis of the cells in non-idet P40 resulted in the solubilization of tissue-specific antigens and of concanavalin A receptors. These specificities were demonstrated using a radio-immunoprecipitation method. The tissue-specific antigens were recognized using absorbed rabbit anti-rat epidermal cell sera (Lloyd & Darnule 1974); they reacted with two low molecular weight components in the lysate (9,000 and 12,000 daltons). Concanavalin A reacted with three major components. Two had high molecular weights (75,000 and 95,000 daltons). The possibility that one of these components was radioiodinated lactooperoxidase, which would have reacted with concanavalin A, was disproved. Another component (which occasionally appeared as two peaks) was similar in size to the species detected by the tissue-specific antisera. Their non-identity was, however, demonstrated by the finding that the two specificities could be precipitated independently of each other.

Animals

Epigenetic maps of pearl millet reveal a prominent role for CHH methylation in regulating tissue-specific gene expression.

UNLABELLED: Pearl millet (Pennisetum glaucum) is a major staple food in arid and semi-arid regions of sub-Saharan Africa, India, and South Asia. However, how epigenetic mechanisms regulate tissue-specific gene expression in this crop remains poorly understood. In this study, we profiled multiple epigenetic features in the young panicles and roots of pearl millet using RNA-seq, ATAC-seq, whole-genome bisulfite sequencing, and ChIP-seq (H3K4me3 and H3K36me3). We identified thousands of genes that were differentially expressed between these two tissues. Root-specific genes were enriched for plant hormone signaling, oxidative phosphorylation, and stress responses. Analysis of chromatin accessibility revealed that root-specific accessible chromatin regions (ACRs) were enriched in binding motifs for stress-responsive transcription factors (e.g., NAC, WRKY), whereas ACRs in young panicles were enriched in motifs for developmental regulators (e.g., AP2/ERF). DNA methylation profiling revealed 25,141 tissue-specific differentially methylated regions, with CHH methylation-rather than CG or CHG methylation-showing the strongest tissue specificity. Promoters of root-specific genes had higher levels of CHH methylation compared to those of young panicle-specific genes, suggesting that the roles of CHH methylation in regulating transcription might be tissue dependent. Notably, promoter-associated H3K4me3 marked panicle-specific genes, whereas root-specific expression was primarily linked to chromatin accessibility, suggesting a transcription factor-mediated regulatory mechanism. Together, our findings highlight the distinct epigenetic frameworks governing tissue-specific gene expression in pearl millet and provide valuable insights for advancing the genetic improvement of this crop. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s42994-025-00243-2.

CHH methylation

Tissue specificity of inhibitory action of excess thyroid hormone on creatine transport in the rat.

Tissue specificities in inhibitory action of excess triiodothyronine (T3) on creatine uptake from the plasma and the effect of denervation of the muscle on the inhibitory action were studied in rats with the use of radioactive creatine. The uptake of radioactive creatine of all muscles studied significantly diminished after T3 (100 microgram/100 g, s.c.) injection, while that of brain was not affected by T3 treatment. Tissue specificity of the T3 action on creatine uptake was consistent with that of previously known T3 action on oxygen consumption. The responses to inhibitory action of T3 on creatine uptake were not different in different types of the skeletal muscles. Although the uptake of radioactive creatine of denervated muscles was significantly lower than that of controls, inhibitory action of T3 on creatine uptake was similarly observed in denervated muscles as well as in normal ones. The results indicate that T3 has a direct effect on muscle cell per se and the inhibitory action of T3 on creatine uptake by the muscle is closely related to T3 action on the energy-requiring process in cell membrane.

Animals

Integrated Metabolomic and Transcriptomic Analysis Reveals Tissue-Specific Secondary Metabolic Differentiation and Indole Alkaloid Accumulation in Evodia rutaecarpa.

Evodia rutaecarpa is a valuable medicinal plant, yet its non-medicinal tissues remain largely underexplored. Here, we integrated ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS)-based widely targeted metabolomics and RNA sequencing (RNA-seq) transcriptomics to systematically profile the metabolic and transcriptional landscapes of roots, stems, leaves, and flowers of Evodia rutaecarpa (Juss.) Benth. Our aim was to characterize tissue-specific metabolic differentiation and its underlying transcriptional regulatory mechanisms. Metabolomic analysis, employing principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) with robust model parameters (R2Y > 0.9, Q2 > 0.5), identified 3090 differential metabolite features (variable importance in projection, VIP > 1.0; p < 0.05) across the four tissues, which exhibited distinct tissue-specific clustering patterns. Integrated Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis and weighted gene co-expression network analysis (WGCNA) revealed that roots specifically accumulated quinolone alkaloids and flavonoid glycosides, accompanied by the coordinated upregulation of genes involved in flavonoid and phenylpropanoid biosynthetic pathways. In contrast, stems, leaves, and flowers were enriched in indole alkaloids (evodiamine and rutaecarpine) and volatile oil precursors, with concurrent upregulation of genes involved in tryptophan metabolism and indole alkaloid biosynthesis (e.g., tryptophan decarboxylase, TDC; s N-methyltransferase, NMT). Notably, leaves and flowers displayed particularly high accumulation levels of these bioactive alkaloids, suggesting their potential as alternative sources for industrial and pharmaceutical applications. WGCNA further identified multiple transcription factors and structural gene modules tightly correlated with evodiamine accumulation, offering promising candidate regulators for future biosynthetic pathway engineering. Collectively, this multi-omics integration study systematically elucidates the tissue-partitioned secondary metabolism of Evodia rutaecarpa (Juss.) Benth. and provides a solid scientific foundation for full-plant resource utilization, targeted development of non-medicinal tissues, and future metabolic engineering of indole alkaloid production.

Evodia rutaecarpa

Lateral and transmembrane redistribution of tissue-specific antigens in single cells and monolayers.

Tissue-specific antigens in the membranes of corneal endothelial cells react with anti-tissue antibodies only in metabolically active monolayers and dispersed cells. After metabolic inhibition by exposure of these preparations to cold, the antigen-antibody complexes, like free antigens, undergo transmembrane redistribution leading to their internalization by the cells. This transmembrane redistribution is reversible and can be followed by using fluorescein-labeled antibodies. Reexpression of the complexes on the cell surfaces occurs after return from metabolic inhibition to metabolic activity. Dispersed corneal endothelial cells are also capable of lateral redistribution (capping) of the complexes although cells in monolayers do not share this capability. Capping in the dispersed cells occurs only at ambient temperatures and, because it results in shedding of the complexes, is irreversible. The data indicate that macromolecules in the membranes of cells organized in tissues are restricted in their movement as compared to the macromolecules of cells functioning in a dispersed state.

Animals

[A tissue specific antigen in rats with malignancies in vitro].

By means of a semiquantitative antigenic analysis in the reaction of precipitation in agar with the use of a monospecific serum, obtained by the authors, dynamical changes have been studied in the content of the tissue-specific antigen in cells of subcutaneous connective tissue in rats: in the original and tripsinzed tissues, in 3, 6, 16-day and 1--2--3 month and malignized cultures, as well. It was found that at the 3, 11--13 day and then in 2--3 months of explantation there was a decrease in the content of the tissue-specific antigen, that is positively correlated with the degree of cell differentiation.

Animals

Increased in vitro tetraploidy: tissue specific within the heritable colorectal cancer syndromes with polyposis coli.

In vivo expression of human hereditary tumors are known to be tissue specific; in familial polyposis coli the genotype is expressed solely as colonic polyps that become malignant and in the Gardner syndrome as extracolonic connective tissue tumors and related neoplasms in addition to such colonic lesions. In vitro such tissue specificity was also seen in these 2 syndromes. Increased tetraploidy has been observed only in those cultures derived from tissues, which although appearing normal in the patient, were known to undergo malignant transformation in vivo based on clinical phenotypes and family histories: colonic mucosa in familial polyposis coli, skin and colonic mucosa in the Gardner syndrome. Cultures established from tissues known not to show neoplastic growth or from benign tumors (fibromas, sebaceous cysts and lipomas) did not show increased tetraploidy. Increased tetraploidy in cultures established from these 2 syndromes did not identify all cultured cells with either mutant genotype or those cells showing abnormal benign growths in vivo but rather only in those that are known to undergo malignant transformation in vivo in both syndromes. Such observations suggested that in these 2 syndromes there was a population of tetraploid cells, at least in culture, constantly present which may be relevant to the multi-step process of carcinogenesis.

Adolescent