PDP-1 Links the TGF-β and IIS Pathways to Regulate Longevity, Development, and Metabolism

Narasimhan, Sri Devi; Yen, Kelvin; Bansal, Ankita; Kwon, Eun-Soo; Padmanabhan, Srivatsan; Tissenbaum, Heidi A.

doi:10.1371/journal.pgen.1001377

Cited by 72 publications

(64 citation statements)

References 82 publications

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“…Since the proliferation of breast cancer cells requires insulin receptor signaling, the two inhibitory compounds we identified may partially block the cell cycle and thereby impact p179SMAD3/SMAD4 complexes. The possible connection between the insulin and TGF-␤ receptor pathways is in line with genetic evidence in Caenorhabditis elegans for such a relation (29). The data may thus imply that the insulin receptor pathway either suppresses a phosphatase or induces the activity of a kinase that targets the phosphorylation of Thr 179 in SMAD3.…”

Section: Cdk4 Inhibitors Reduce Levels Of P179smad3-supporting

confidence: 69%

Single Chain Antibodies as Tools to Study transforming growth factor-β-Regulated SMAD Proteins in Proximity Ligation-Based Pharmacological Screens

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Hust

et al. 2016

Molecular & Cellular Proteomics

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The cellular heterogeneity seen in tumors, with subpopulations of cells capable of resisting different treatments, renders single-treatment regimens generally ineffective. Accordingly, there is a great need to increase the repertoire of drug treatments from which combinations may be selected to efficiently target sets of pathological processes, while suppressing the emergence of resistance mutations. In this regard, members of the TGF-␤ signaling pathway may furnish new, valuable therapeutic targets. In the present work, we developed in situ proximity ligation assays (isPLA) to monitor the state of the TGF-␤ signaling pathway. Moreover, we extended the range of suitable affinity reagents for this analysis by developing a set of in-vitro-derived human antibody fragments (single chain fragment variable, scFv) that bind SMAD2 (Mothers against decapentaplegic 2), 3, 4, and 7 using phage display. These four proteins are all intracellular mediators of TGF-␤ signaling. We also developed an scFv specific for SMAD3 phosphorylated in the linker domain 3 (p179 SMAD3). This phosphorylation has been shown to inactivate the tumor suppressor function of SMAD3. The single chain affinity reagents developed in the study were fused tocrystallizable antibody fragments (Fc-portions) and expressed as dimeric IgG-like molecules having Fc domains (Yumabs), and we show that they represent valuable reagents for isPLA.Using these novel assays, we demonstrate that p179 SMAD3 forms a complex with SMAD4 at increased frequency during division and that pharmacological inhibition of cyclin-dependent kinase 4 (CDK4) 1 reduces the levels of p179SMAD3 in tumor cells. We further show that the p179SMAD3-SMAD4 complex is bound for degradation by the proteasome. Finally, we developed a chemical screening strategy for compounds that reduce the levels of p179SMAD3 in tumor cells with isPLA as a read-out, using the p179SMAD3 scFv SH544-IIC4. The screen identified two kinase inhibitors, known inhibitors of the insulin receptor, which decreased levels of p179SMAD3/SMAD4 complexes, thereby demonstrating the suitability of the recombinant affinity reagents applied in isPLA in screening for inhibitors of cell signaling. Molecular & Cellular

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Section: Cdk4 Inhibitors Reduce Levels Of P179smad3-supporting

confidence: 69%

Single Chain Antibodies as Tools to Study transforming growth factor-β-Regulated SMAD Proteins in Proximity Ligation-Based Pharmacological Screens

Blokzijl

Zięba

Hust

et al. 2016

Molecular & Cellular Proteomics

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“…The increased body fat of daf-2 mutants is abrogated by loss of the canonical FOXO transcription factor daf-16 . From an RNAi screen, a protein phosphatase called pdp-1 with sequence similarity to the mammalian pyruvate dehydrogenase phosphatase emerged as a link between the insulin and TGFβ signaling pathways (78). However, regulators of insulin-signaling-mediated body fat control distinct from its effects on dauer and lifespan regulation are yet to be identified.…”

Section: Neuronal Control Of Body Fatmentioning

confidence: 99%

Regulation of Body Fat in Caenorhabditis elegans

Srinivasan

2015

Annu. Rev. Physiol.

102

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Studies conducted in C. elegans over the last decade highlight the ancient and complex origins of body fat regulation. In this critical review, I introduce the major functional approaches used to study energy balance and body fat, the lipid composition of C. elegans, the regulation of cellular fat metabolism and its transcriptional control. Next I describe the influence of the sensory nervous system on body fat and the major regulatory mechanisms that couple food perception in the nervous system with the production of energy via fat metabolism. The final section describes the opportunities for the discovery of neuroendocrine factors that control communication between the nervous system and the metabolic tissues. The coming years are expected to reveal a wealth of information on the neuroendocrine control of body fat in C. elegans.

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“…Lowering daf-7 expression permits activation of the downstream DAF-3/DAF-5 complex (Patterson et al, 1997; da Graca et al, 2004). Crosstalk between pathways then results in modulation of the insulin-like and nuclear hormone receptor pathways (Gerisch et al, 2001; Narasimhan et al, 2011). Perhaps for this reason, daf-7(e1372) dauer larvae appear grossly similar to wild-type dauer larvae.…”

Section: Methods To Induce Dauer Formationmentioning

confidence: 99%