A PDX1 cistrome and single-cell transcriptome resource of the developing pancreas.

Pancreatic and duodenal homeobox 1 (PDX1) is crucial for pancreas organogenesis, yet the dynamic changes in PDX1 binding in human or mouse developing pancreas have not been examined. To address this knowledge gap, we performed PDX1 ChIP-seq and single-cell RNA-seq using fetal human pancreata. We integrated our datasets with published datasets and revealed the dynamics of PDX1 binding and potential cell lineage-specific PDX1-bound genes in the pancreas from fetal to adult stages.

Fibroblasts Derived From Human Adipose Stem Cells Produce More Effective Extracellular Matrix and Migrate Faster Compared to Primary Dermal Fibroblasts.

Background: The efficacy of adipose-derived stem cells (ASCs) to improve wound healing has been extensively investigated. Unfortunately, no consistent reports have described significant improvements in healing time or outcomes in large-scale clinical trials utilizing human ASCs. Primarily, these studies examined undifferentiated ASCs as opposed to specific cells differentiated from ASCs.

HEART DEVELOPMENT. Integration of Bmp and Wnt signaling by Hopx specifies commitment of cardiomyoblasts.

Cardiac progenitor cells are multipotent and give rise to cardiac endothelium, smooth muscle, and cardiomyocytes. Here, we define and characterize the cardiomyoblast intermediate that is committed to the cardiomyocyte fate, and we characterize the niche signals that regulate commitment. Cardiomyoblasts express Hopx, which functions to coordinate local Bmp signals to inhibit the Wnt pathway, thus promoting cardiomyogenesis.

Diabetes Susceptibility Genes Pdx1 and Clec16a Function in a Pathway Regulating Mitophagy in β-Cells.

Mitophagy is a critical regulator of mitochondrial quality control and is necessary for elimination of dysfunctional mitochondria to maintain cellular respiration. Here, we report that the homeodomain transcription factor Pdx1, a gene associated with both type 2 diabetes and monogenic diabetes of the young, regulates mitophagy in pancreatic β-cells. Loss of Pdx1 leads to abnormal mitochondrial morphology and function as well as impaired mitochondrial turnover.

Tshz1 Regulates Pancreatic β-Cell Maturation.

The homeodomain transcription factor Pdx1 controls pancreas organogenesis, specification of endocrine pancreas progenitors, and the postnatal growth and function of pancreatic β-cells. Pdx1 expression in human-derived stem cells is used as a marker for induced pancreatic precursor cells. Unfortunately, the differentiation efficiency of human pancreatic progenitors into functional β-cells is poor.

Epigenetic priming of enhancers predicts developmental competence of hESC-derived endodermal lineage intermediates.

Embryonic development relies on the capacity of progenitor cells to appropriately respond to inductive cues, a cellular property known as developmental competence. Here, we report that epigenetic priming of enhancers signifies developmental competence during endodermal lineage diversification. Chromatin mapping during pancreatic and hepatic differentiation of human embryonic stem cells revealed the en masse acquisition of a poised chromatin state at enhancers specific to endoderm-derived cell lineages in gut tube intermediates.

Insulin regulates carboxypeptidase E by modulating translation initiation scaffolding protein eIF4G1 in pancreatic β cells.

Insulin resistance, hyperinsulinemia, and hyperproinsulinemia occur early in the pathogenesis of type 2 diabetes (T2D). Elevated levels of proinsulin and proinsulin intermediates are markers of β-cell dysfunction and are strongly associated with development of T2D in humans. However, the mechanism(s) underlying β-cell dysfunction leading to hyperproinsulinemia is poorly understood.

Hnf1α (MODY3) regulates β-cell-enriched MafA transcription factor expression.

The expression pattern of genes important for pancreatic islet cell function requires the actions of cell-enriched transcription factors. Musculoaponeurotic fibrosarcoma homolog A (MafA) is a β-cell-specific transcriptional activator critical to adult islet β-cell function, with MafA mutant mice manifesting symptoms associated with human type 2 diabetes. Here, we describe that MafA expression is controlled by hepatocyte nuclear factor 1-α (Hnf1α), the transcription factor gene mutated in the most common monoallelic form of maturity onset diabetes of the young.

Calcineurin signaling regulates human islet {beta}-cell survival.

The calcium-regulated phosphatase calcineurin intersects with both calcium and cAMP-mediated signaling pathways in the pancreatic β-cell. Pharmacologic calcineurin inhibition, necessary to prevent rejection in the setting of organ transplantation, is associated with post-transplant β-cell failure. We sought to determine the effect of calcineurin inhibition on β-cell replication and survival in rodents and in isolated human islets.

Islet beta-cell-specific MafA transcription requires the 5'-flanking conserved region 3 control domain.

MafA is a key transcriptional activator of islet beta cells, and its exclusive expression within beta cells of the developing and adult pancreas is distinct among pancreatic regulators. Region 3 (base pairs -8118 to -7750 relative to the transcription start site), one of six conserved 5' cis domains of the MafA promoter, is capable of directing beta-cell-line-selective expression. Transgenic reporters of region 3 alone (R3), sequences spanning regions 1 to 6 (R1-6; base pairs -10428 to +230), and R1-6 lacking R3 (R1-6(DeltaR3)) were generated.

MafB is required for islet beta cell maturation.

Pancreatic endocrine cell differentiation depends on transcription factors that also contribute in adult insulin and glucagon gene expression. Islet cell development was examined in mice lacking MafB, a transcription factor expressed in immature alpha (glucagon(+)) and beta (insulin(+)) cells and capable of activating insulin and glucagon expression in vitro. We observed that MafB(-/-) embryos had reduced numbers of insulin(+) and glucagon(+) cells throughout development, whereas the total number of endocrine cells was unchanged.

FoxA2, Nkx2.2, and PDX-1 regulate islet beta-cell-specific mafA expression through conserved sequences located between base pairs -8118 and -7750 upstream from the transcription start site.

The MafA transcription factor is both critical to islet beta-cell function and has a unique pancreatic cell-type-specific expression pattern. To localize the potential transcriptional regulatory region(s) involved in directing expression to the beta cell, areas of identity within the 5' flanking region of the mouse, human, and rat mafA genes were found between nucleotides -9389 and -9194, -8426 and -8293, -8118 and -7750, -6622 and -6441, -6217 and -6031, and -250 and +56 relative to the transcription start site. The identity between species was greater than 75%, with the highest found between bp -8118 and -7750 ( approximately 94%, termed region 3).

FoxO1 protects against pancreatic beta cell failure through NeuroD and MafA induction.

Diabetes causes pancreatic beta cell failure through hyperglycemia-induced oxidative stress, or "glucose toxicity." We show that the forkhead protein FoxO1 protects beta cells against oxidative stress by forming a complex with the promyelocytic leukemia protein Pml and the NAD-dependent deacetylase Sirt1 to activate expression of NeuroD and MafA, two Insulin2 (Ins2) gene transcription factors. Using acetylation-defective and acetylation-mimicking mutants, we demonstrate that acetylation targets FoxO1 to Pml and prevents ubiquitin-dependent degradation.