7 research outputs found
Targeting Native Adult Heart Progenitors with Cardiogenic Small Molecules
Targeting native progenitors with small molecule pharmaceuticals
that direct cell fate decisions is an attractive approach for regenerative
medicine. Here, we show that 3,5-disubstituted isoxazoles (Isx), stem
cell-modulator small molecules originally recovered in a P19 embryonal
carcinoma cell-based screen, directed cardiac muscle gene expression <i>in vivo</i> in target tissues of adult transgenic reporter mice.
Isx also stimulated adult mouse myocardial cell cycle activity. Narrowing
our focus onto one target cardiac-resident progenitor population,
Isx directed muscle transcriptional programs <i>in vivo</i> in multipotent Notch-activated epicardium-derived cells (NECs),
generating Notch-activated adult cardiomyocyte-like precursors. Myocardial
infarction (MI) preemptively differentiated NECs toward fibroblast
lineages, overriding Isx’s cardiogenic influence in this cell
population. Isx dysregulated gene expression <i>in vivo</i> in Notch-activated repair fibroblasts, driving distinctive (pro-angiogenesis)
gene programs, but failed to mitigate fibrosis or avert ventricular
functional decline after MI. In NECs <i>in vitro</i>, Isx
directed partial muscle differentiation, which included biosynthesis
and assembly of sarcomeric α-actinin premyofibrils, beaded structures
pathognomonic of early developing cardiomyocytes. Thus, although Isx
small molecules have promising <i>in vivo</i> efficacy at
the level of cardiac muscle gene expression in native multipotent
progenitors and are first in class in this regard, a greater understanding
of the dynamic interplay between fibrosis and cardiogenic small molecule
signals will be required to pharmacologically enable regenerative
repair of the heart
Regulated Expression of pH Sensing G Protein-Coupled Receptor-68 Identified through Chemical Biology Defines a New Drug Target for Ischemic Heart Disease
Chemical biology promises discovery of new and unexpected
mechanistic
pathways, protein functions and disease targets. Here, we probed the
mechanism-of-action and protein targets of 3,5-disubstituted isoxazoles
(Isx), cardiomyogenic small molecules that target Notch-activated
epicardium-derived cells (NECs) <i>in vivo</i> and promote
functional recovery after myocardial infarction (MI). Mechanistic
studies in NECs led to an Isx-activated G<sub>q</sub> protein-coupled
receptor (G<sub>q</sub>PCR) hypothesis tested in a cell-based functional
target screen for GPCRs regulated by Isx. This screen identified one
agonist hit, the extracellular proton/pH-sensing GPCR GPR68, confirmed
through genetic gain- and loss-of-function. Overlooked until now,
GPR68 expression and localization were highly regulated in early post-natal
and adult post-infarct mouse heart, where GPR68-expressing cells accumulated
subepicardially. Remarkably, GPR68-expressing cardiomyocytes established
a proton-sensing cellular “buffer zone” surrounding
the MI. Isx pharmacologically regulated gene expression (mRNAs and
miRs) in this GPR68-enriched border zone, driving cardiomyogenic and
pro-survival transcriptional programs <i>in vivo</i>. In
conclusion, we tracked a (micromolar) bioactive small molecule’s
mechanism-of-action to a candidate target protein, GPR68, and validated
this target as a previously unrecognized regulator of myocardial cellular
responses to tissue acidosis, setting the stage for future (nanomolar)
target-based drug lead discovery
Isoxazole Alters Metabolites and Gene Expression, Decreasing Proliferation and Promoting a Neuroendocrine Phenotype in β‑Cells
Novel strategies are needed to modulate
β-cell differentiation
and function as potential β-cell replacement or restorative
therapies for diabetes. We previously demonstrated that small molecules
based on the isoxazole scaffold drive neuroendocrine phenotypes. The
nature of the effects of isoxazole compounds on β-cells was
incompletely defined. We find that isoxazole induces genes that support
neuroendocrine and β-cell phenotypes and suppresses genes important
for proliferation. Isoxazole alters β-cell metabolites and protects
glucose-responsive signaling pathways under lipotoxic conditions.
Finally, we show that isoxazole improves glycemia in a mouse model
of β-cell regeneration. Isoxazole is a prime candidate to alter
cell fate in different contexts
Isoxazole Alters Metabolites and Gene Expression, Decreasing Proliferation and Promoting a Neuroendocrine Phenotype in β‑Cells
Novel strategies are needed to modulate
β-cell differentiation
and function as potential β-cell replacement or restorative
therapies for diabetes. We previously demonstrated that small molecules
based on the isoxazole scaffold drive neuroendocrine phenotypes. The
nature of the effects of isoxazole compounds on β-cells was
incompletely defined. We find that isoxazole induces genes that support
neuroendocrine and β-cell phenotypes and suppresses genes important
for proliferation. Isoxazole alters β-cell metabolites and protects
glucose-responsive signaling pathways under lipotoxic conditions.
Finally, we show that isoxazole improves glycemia in a mouse model
of β-cell regeneration. Isoxazole is a prime candidate to alter
cell fate in different contexts
Isoxazole Alters Metabolites and Gene Expression, Decreasing Proliferation and Promoting a Neuroendocrine Phenotype in β‑Cells
Novel strategies are needed to modulate
β-cell differentiation
and function as potential β-cell replacement or restorative
therapies for diabetes. We previously demonstrated that small molecules
based on the isoxazole scaffold drive neuroendocrine phenotypes. The
nature of the effects of isoxazole compounds on β-cells was
incompletely defined. We find that isoxazole induces genes that support
neuroendocrine and β-cell phenotypes and suppresses genes important
for proliferation. Isoxazole alters β-cell metabolites and protects
glucose-responsive signaling pathways under lipotoxic conditions.
Finally, we show that isoxazole improves glycemia in a mouse model
of β-cell regeneration. Isoxazole is a prime candidate to alter
cell fate in different contexts
Isoxazole Alters Metabolites and Gene Expression, Decreasing Proliferation and Promoting a Neuroendocrine Phenotype in β‑Cells
Novel strategies are needed to modulate
β-cell differentiation
and function as potential β-cell replacement or restorative
therapies for diabetes. We previously demonstrated that small molecules
based on the isoxazole scaffold drive neuroendocrine phenotypes. The
nature of the effects of isoxazole compounds on β-cells was
incompletely defined. We find that isoxazole induces genes that support
neuroendocrine and β-cell phenotypes and suppresses genes important
for proliferation. Isoxazole alters β-cell metabolites and protects
glucose-responsive signaling pathways under lipotoxic conditions.
Finally, we show that isoxazole improves glycemia in a mouse model
of β-cell regeneration. Isoxazole is a prime candidate to alter
cell fate in different contexts
Isoxazole Alters Metabolites and Gene Expression, Decreasing Proliferation and Promoting a Neuroendocrine Phenotype in β‑Cells
Novel strategies are needed to modulate
β-cell differentiation
and function as potential β-cell replacement or restorative
therapies for diabetes. We previously demonstrated that small molecules
based on the isoxazole scaffold drive neuroendocrine phenotypes. The
nature of the effects of isoxazole compounds on β-cells was
incompletely defined. We find that isoxazole induces genes that support
neuroendocrine and β-cell phenotypes and suppresses genes important
for proliferation. Isoxazole alters β-cell metabolites and protects
glucose-responsive signaling pathways under lipotoxic conditions.
Finally, we show that isoxazole improves glycemia in a mouse model
of β-cell regeneration. Isoxazole is a prime candidate to alter
cell fate in different contexts