Deficiency of Splicing Factor 1 (SF1) Reduces Intestinal Polyp Incidence in ApcMin/+ Mice

Background: Splicing factor 1 (SF1) is a conserved alternative splicing factor expressed in many different mammalian cell types. The genetically modified Sf1+/− (or Sf1β-geo/+) mice express reduced levels of SF1 protein in mouse tissues, including in cells of the intestines. Mutational inactivation of human adenomatous polyposis coli (APC) gene deregulates the Wnt signaling pathway and is a frequent genetic event in colon cancers. Mice with a point mutation in the Apc gene (ApcMin/+) also develop numerous intestinal polyps at a young age. Our aim was to determine the effect of reduced SF1 levels on polyp development due to the strong driver ApcMin/+ mutation. Methods: We utilized mice genetically deficient for expression of SF1 to assess how SF1 levels affect intestinal tumorigenesis. We crossed ApcMin/+ to Sf1+/− mice to generate a cohort of heterozygous mutant ApcMin/+;Sf1+/− mice and compared intestinal polyp development in these mice to that in a control cohort of sibling ApcMin/+ mice. We compared total polyp numbers, sizes of polyps and gender differences in polyp numbers between ApcMin/+;Sf1+/− and ApcMin/+ mice. Results: Our results showed that ApcMin/+ mice with lower SF1 expression developed 25–30% fewer intestinal polyps compared to their ApcMin/+ siblings with normal SF1 levels. Interestingly, this difference was most significant for females (ApcMin/+;Sf1+/− and ApcMin/+ females developed 39 and 55 median number of polyps, respectively). Furthermore, the difference in polyp numbers between ApcMin/+;Sf1+/− and ApcMin/+ mice was significant for smaller polyps with a size of 2 mm or less, whereas both groups developed similar numbers of larger polyps. Conclusions: Our results suggest that lower SF1 levels likely inhibit the rate of initiation of polyp development due to ApcMin/+ driver mutation in the mouse intestine. Thus, therapeutic lowering of SF1 levels in the intestine could attenuate intestinal polyp development.

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Immunohistochemical localization of phosphoenolpyruvate carboxykinase in adult and developing mouse tissues.

Journal of Histochemistry & Cytochemistry ◽

10.1177/38.2.1688895 ◽

1990 ◽

Vol 38 (2) ◽

pp. 171-178 ◽

Cited By ~ 47

Author(s):

D B Zimmer ◽

M A Magnuson

Keyword(s):

Nervous System ◽

Phosphoenolpyruvate Carboxykinase ◽

Submaxillary Gland ◽

Cell Types ◽

Immunohistochemical Localization ◽

Mouse Tissues ◽

Multiple Cell ◽

Cell Type Specific ◽

Immunohistochemical Techniques ◽

Developing Nervous System

We used immunohistochemical techniques to analyze the cell distribution of phosphoenolpyruvate carboxykinase (PEPCK) in adult and developing mouse tissues. PEPCK immunoreactivity was detected in many tissues, including some that had not been previously reported to contain PEPCK enzyme activity (bladder, stomach, ovary, vagina, parotid gland, submaxillary gland, and eye). In some multicellular tissues, PEPCK immunoreactivity was observed in multiple cell types. Several tissues (spleen, thyroid, and submaxillary gland) contained no detectable PEPCK immunoreactivity. During development, PEPCK immunoreactivity was associated with the developing nervous system and somites in 15-day embryos. At prenatal day 18, PEPCK immunoreactivity was detected only in the nervous system. At prenatal day 20, PEPCK immunoreactivity was observed in many of the tissues that contain PEPCK in the adult, with the exception of liver, lung, and stomach. PEPCK immunoreactivity was detected in liver at postnatal day 1, lung at postnatal day 7, and stomach after postnatal day 21. The only tissue in which PEPCK immunoreactivity decreased during development was the pancreas, where PEPCK immunoreactivity was detected at prenatal day 20 and was present until postnatal day 21. These results suggest that PEPCK expression is cell-type specific, more widespread than previously thought, and differentially expressed during development.

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PF-06939999, a potent and selective PRMT5 inhibitor, in patients with advanced or metastatic solid tumors: A phase 1 dose escalation study.

Journal of Clinical Oncology ◽

10.1200/jco.2021.39.15_suppl.3019 ◽

2021 ◽

Vol 39 (15_suppl) ◽

pp. 3019-3019

Author(s):

Jordi Rodon Ahnert ◽

Cesar Augusto Perez ◽

Kit Man Wong ◽

Michael L. Maitland ◽

Frank Tsai ◽

...

Keyword(s):

Solid Tumors ◽

Dose Escalation ◽

Urothelial Cancer ◽

Phase 1 ◽

Dose Range ◽

Median Number ◽

Splicing Factor ◽

Dose Escalation Study ◽

Study Objective ◽

Dose Dependent

3019 Background: Protein arginine methyltransferase 5 (PRMT5) methylates multiple substrates known to be dysregulated in cancer, including components of the spliceosome machinery. PF-06939999 is a selective small-molecule inhibitor of PRMT5. Here we report the safety, PK, PD, and preliminary activity of PF-06939999 in patients (pts) with selected advanced/metastatic solid tumors. Methods: This phase 1 dose escalation trial (NCT03854227) enrolled pts with solid tumor types marked by potential frequent splicing factor mutations, including advanced/metastatic endometrial cancer, head and neck squamous cell carcinoma (HNSCC), non-small cell lung cancer (NSCLC), urothelial cancer, cervical cancer, or esophageal cancer. PF-06939999 monotherapy was continuously administered orally QD or BID in 28-day cycles. A Bayesian Logistic Regression Model was used to inform dose level decisions. Primary objectives were to assess dose limiting toxicities (DLTs), AEs and laboratory abnormalities. Tumor response was assessed using RECIST v1.1. PK and PD were assessed by determining PF-06939999 plasma concentration after dosing and changes in plasma levels of symmetric di-methyl arginine (SDMA), the product of PRMT5 enzymatic activity. Results: 28 pts received PF-06939999 at doses from 0.5-12 mg daily (QD or BID) during dose escalation. Median number of cycles was 2 (range, 1-13). Most were female (54%) with a median age of 61.5 (range, 32-84) y. Median number of prior therapies was 4. Overall, 4/24 (17%) pts reported DLTs: thrombocytopenia (n=2, 6 mg BID); anemia (n=1, 8 mg QD); and neutropenia (n=1, 6 mg QD). Treatment-related AEs occurred in 24 (86%) pts. Most common (≥20%) treatment-related AEs across all cycles were anemia (43%), thrombocytopenia (32%), dysgeusia, fatigue and nausea (29% each). Grade ≥3 treatment-related AEs included anemia (25%), thrombocytopenia (21%), fatigue, neutropenia and lymphocyte count decreased (4% each). One pt (6mg BID) had Grade 4 treatment-related thrombocytopenia. All cytopenias were dose-dependent and reversible with dose modification. No pts discontinued treatment for treatment-related toxicity. There were no treatment-related deaths. Exposure to PF-06939999 increased with doses in the dose range tested. Plasma SDMA was reduced at steady state (58.4-87.5%), indicating robust PD target inhibition. Two pts had confirmed partial response (HNSCC and NSCLC). 6 mg QD was identified as the recommended monotherapy dose for expansion. Conclusions: PF-06939999 showed dose-dependent and manageable toxicities in this phase 1 dose escalation study. Objective tumor responses were observed in pts with HNSCC and NSCLC. Analysis of archival tissue for the presence of splicing factor mutations and other potential predictive biomarkers is ongoing. Enrollment to part 2 dose expansion is ongoing in pts with NSCLC, HNSCC and urothelial cancer. Clinical trial information: NCT03854227.

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c-mos proto-oncogene RNA transcripts in mouse tissues: structural features, developmental regulation, and localization in specific cell types.

Molecular and Cellular Biology ◽

10.1128/mcb.7.5.1629 ◽

1987 ◽

Vol 7 (5) ◽

pp. 1629-1637 ◽

Cited By ~ 94

Author(s):

F Propst ◽

M P Rosenberg ◽

A Iyer ◽

K Kaul ◽

G F Vande Woude

Keyword(s):

Developmental Regulation ◽

Cell Types ◽

Structural Features ◽

Specific Cell ◽

Cell Fractionation ◽

Gonadal Tissue ◽

Rna Transcripts ◽

Adult Mice ◽

Germ Cell Differentiation ◽

Mouse Tissues

c-mos RNA transcripts have been previously detected in mouse gonadal tissue and in late-term embryos. Here, we show that they are also present at low levels in placenta and in adult mouse brain, kidney, mammary gland, and epididymis. Marked differences are observed in the size of the mos RNA transcripts detected in different tissues. All transcripts appear to end at the same 3' position, and the tissue-specific size variations appear to be due to the use of different promoters. For example, the testicular and ovarian RNA transcripts initiate approximately 280 and approximately 70 base pairs, respectively, upstream from the first initiation codon, but both end at a common site downstream from the mos open reading frame. The expression of mos is developmentally regulated in gonadal tissue. Thus, the level of mos transcripts in testes is low for the first 3 weeks after birth, increases at least 10-fold around day 25, and reaches adult levels by day 30. In contrast, ovaries from preweaning mice contain a higher level of mos mRNA compared to ovaries from adult mice. In cell fractionation experiments we show that mos transcripts are present in haploid germ cells. We find that these transcripts are associated with monosomes and polysomes. The peculiar pattern of mos expression in mouse gonadal tissue suggests a role for the c-mos proto-oncogene in germ cell differentiation.

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Selective activation of a discrete family of endogenous proviral elements in normal BALB/c lymphocytes

Molecular and Cellular Biology ◽

10.1128/mcb.12.1.220-228.1992 ◽

1992 ◽

Vol 12 (1) ◽

pp. 220-228

Author(s):

J A Mietz ◽

J W Fewell ◽

E L Kuff

Keyword(s):

Normal Mouse ◽

Methylation Status ◽

Regulatory Region ◽

Cell Types ◽

Cdna Libraries ◽

Cdna Clones ◽

Sequence Specificity ◽

Selective Activation ◽

Mouse Tissues ◽

R Region

Intracisternal A-particle (IAP) proviral elements are abundant and widely dispersed in the mouse genome. IAP-related transcripts have been detected in normal mouse tissues where expression is under genetic control. In this study, we sought to determine whether IAP expression in BALB/c thymus and lipopolysaccharide-stimulated B cells was due to selective or indiscriminate activation of IAP elements. cDNA libraries were prepared from each source. A total of 86 IAP cDNA clones were isolated from both libraries, and 37 of these were sequenced over a common 0.7- to 1.0-kb region of the IAP genome that included the 3' long terminal repeat (LTR). Three highly related families of elements were found to be expressed in the two cell types examined. All of the related elements had a distinctive U3 regulatory region. Thirteen individual IAP proviral elements were distinguished on the basis of sequence differences within the R region of the LTR. Hybridization of genomic DNA with element-specific oligonucleotide probes confirmed the presence of a restricted number of proviral copies in the lymphocyte-specific family of elements. Most of these copies were found to be methylated in the lymphocyte DNA, but at least seven were hypomethylated in their 5' LTRs. This study shows that activation of IAP elements in normal normal mouse lymphocytes is highly selective. Activation is probably a function of both sequence specificity and methylation status of the proviral LTR.

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Differential expression of type-specific c-abl mRNAs in mouse tissues and cell lines

Molecular and Cellular Biology ◽

10.1128/mcb.8.10.4547-4551.1988 ◽

1988 ◽

Vol 8 (10) ◽

pp. 4547-4551

Author(s):

M W Renshaw ◽

M A Capozza ◽

J Y Wang

Keyword(s):

Alternative Splicing ◽

Differential Expression ◽

Cell Lines ◽

Relative Abundance ◽

Cell Types ◽

Type I ◽

Rnase Protection ◽

Type Iv ◽

Mouse Tissues ◽

Different Tissues

The mammalian c-abl proto-oncogene produces mRNAs with 5' heterogeneity from two distinct promoters and the alternative splicing of variable 5' exons. By using quantitative RNase protection assays, the relative abundance of two major c-abl mRNAs, type I and type IV, in several mouse tissues and cell lines has been determined. Our results demonstrate that the level of type IV c-abl mRNA is rather constant, whereas that of the type I mRNA varies over a 10-fold range in different tissues and cell types. This finding has interesting implications for the function of the two c-abl proteins.

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Glia and Neural Stem and Progenitor Cells of the Healthy and Ischemic Brain: The Workplace for the Wnt Signaling Pathway

Genes ◽

10.3390/genes11070804 ◽

2020 ◽

Vol 11 (7) ◽

pp. 804

Author(s):

Tomas Knotek ◽

Lucie Janeckova ◽

Jan Kriska ◽

Vladimir Korinek ◽

Miroslava Anderova

Keyword(s):

Wnt Signaling ◽

Progenitor Cells ◽

Current Knowledge ◽

Wnt Signaling Pathway ◽

Cell Types ◽

Negative Effects ◽

Future Directions ◽

Ischemic Brain ◽

Stem And Progenitor Cells ◽

Neural Stem Progenitor Cells

Wnt signaling plays an important role in the self-renewal, fate-commitment and survival of the neural stem/progenitor cells (NS/PCs) of the adult central nervous system (CNS). Ischemic stroke impairs the proper functioning of the CNS and, therefore, active Wnt signaling may prevent, ameliorate, or even reverse the negative effects of ischemic brain injury. In this review, we provide the current knowledge of Wnt signaling in the adult CNS, its status in diverse cell types, and the Wnt pathway’s impact on the properties of NS/PCs and glial cells in the context of ischemic injury. Finally, we summarize promising strategies that might be considered for stroke therapy, and we outline possible future directions of the field.

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Loss of Apc heterozygosity and abnormal tissue building in nascent intestinal polyps in mice carrying a truncated Apc gene.

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.92.10.4482 ◽

1995 ◽

Vol 92 (10) ◽

pp. 4482-4486 ◽

Cited By ~ 362

Author(s):

M. Oshima ◽

H. Oshima ◽

K. Kitagawa ◽

M. Kobayashi ◽

C. Itakura ◽

...

Keyword(s):

Apc Gene ◽

Intestinal Polyps ◽

Abnormal Tissue

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Isolation of cDNA clones for mouse cytoskeletal gamma-actin and differential expression of cytoskeletal actin mRNAs in mouse cells.

Molecular and Cellular Biology ◽

10.1128/mcb.8.9.3929 ◽

1988 ◽

Vol 8 (9) ◽

pp. 3929-3933 ◽

Cited By ~ 22

Author(s):

K Tokunaga ◽

K Takeda ◽

K Kamiyama ◽

H Kageyama ◽

K Takenaga ◽

...

Keyword(s):

Differential Expression ◽

Functional Diversity ◽

Mammalian Cells ◽

Cell Types ◽

Regulatory Mechanisms ◽

Untranslated Regions ◽

Cdna Clones ◽

Expression Levels ◽

Mouse Tissues ◽

Mouse Cells

We described the structures of mouse cytoskeletal gamma-actin cDNA clones and showed that there is strong conservation of the untranslated regions with human gamma-actin cDNA. In addition, we found that the expression levels of beta- and gamma-actin mRNAs are differentially controlled in various mouse tissues and cell types but are coordinately increased in the cellular growing state. These results suggest that there are multiple regulatory mechanisms of cytoskeletal actin genes and are consistent with the argument that beta- and gamma-actins might have functional diversity in mammalian cells.

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The mammalian 43-kD acetylcholine receptor-associated protein (RAPsyn) is expressed in some nonmuscle cells.

The Journal of Cell Biology ◽

10.1083/jcb.108.5.1833 ◽

1989 ◽

Vol 108 (5) ◽

pp. 1833-1840 ◽

Cited By ~ 21

Author(s):

L S Musil ◽

D E Frail ◽

J P Merlie

Keyword(s):

Skeletal Muscle ◽

Acetylcholine Receptor ◽

Cell Lines ◽

Neuromuscular Junctions ◽

Cell Types ◽

Cardiac Cells ◽

Mrna Levels ◽

Receptor Associated Protein ◽

Mouse Tissues ◽

Nonmuscle Cells

Torpedo electric organ and vertebrate neuromuscular junctions contain the receptor-associated protein of the synapse (RAPsyn) (previously referred to as the 43K protein), a nonactin, 43,000-Mr peripheral membrane protein associated with the cytoplasmic face of postsynaptic membranes at areas of high nicotinic acetylcholine receptor (AChR) density. Although not directly demonstrated, several lines of evidence suggest that RAPsyn is involved in the synthesis and/or maintenance of such AChR clusters. Microscopic and biochemical studies had previously indicated that RAPsyn expression is restricted to differentiated, AChR-synthesizing cells. Our recent finding that RAPsyn is also produced in undifferentiated myocytes (Frail, D.E., L.S. Musil, a. Bonanno, and J.P. Merlie, 1989. Neuron. 2:1077-1086) led to to examine whether RAPsyn is synthesized in cell types that never express AChR (i.e., cells of other than skeletal muscle origin). Various primary and established rodent cell lines were metabolically labeled with [35S]methionine, and extracts were immunoprecipitated with a monospecific anti-RAPsyn serum. Analysis of these immunoprecipitates by SDS-PAGE revealed detectable RAPsyn synthesis in some (notably fibroblast and Leydig tumor cell lines and primary cardiac cells) but not all (hepatocyte- and lymphocyte-derived) cell types. These results were further substantiated by peptide mapping studies of RAPsyn immunoprecipitated from different cells and quantitation of RAPsyn-encoding mRNA levels in mouse tissues. RAPsyn synthesized in both muscle and nonmuscle cells was shown to be tightly associated with membranes. These findings demonstrate that RAPsyn is not specific to skeletal muscle-derived cells and imply that it may function in a capacity either in addition to or instead of AChR clustering.

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The LIM Domain Protein Lmo4 Is Highly Expressed in Proliferating Mouse Epithelial Tissues

Journal of Histochemistry & Cytochemistry ◽

10.1369/jhc.4a6553.2005 ◽

2005 ◽

Vol 53 (4) ◽

pp. 475-486 ◽

Cited By ~ 31

Author(s):

Eleanor Y.M. Sum ◽

Lorraine A. O'Reilly ◽

Nadeen Jonas ◽

Geoffrey J. Lindeman ◽

Jane E. Visvader

Keyword(s):

Small Intestine ◽

Mammary Gland ◽

Cell Types ◽

Mammary Epithelial ◽

Specific Cell ◽

Basal Cells ◽

Proliferating Cells ◽

Terminal End Buds ◽

Mouse Tissues ◽

Important Regulator

LMO4 belongs to the LIM-only family of zinc finger proteins that have been implicated in oncogenesis. The LMO4 gene is overexpressed in breast cancer and oral cavity carcinomas, and high levels of this protein inhibit mammary epithelial differentiation. Targeted deletion of Lmo4 in mice leads to complex phenotypic abnormalities and perinatal lethality. To further understand the role of LMO4, we have characterized Lmo4 expression in adult mouse tissues by immunohistochemical staining using monoclonal anti-Lmo4 antibodies. Lmo4 was highly expressed within specific cell types in diverse tissues. Expression was prevalent in epithelial-derived tissues, including the mammary gland, tongue, skin, small intestine, lung, and brain. High levels of Lmo4 were frequently observed in proliferating cells, such as the crypt cells of the small intestine and the basal cells of the skin and tongue. Lmo4 was highly expressed in the proliferative cap cell layer of the terminal end buds in the peripubertal mammary gland and in the lobuloalveolar units during pregnancy. The expression profile of Lmo4 suggests that this cofactor is an important regulator of epithelial proliferation and has implications for its role in the pathogenicity of cancer.

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