Human Pluripotent Stem Cell-Derived Organoids as Models of Liver Disease.

Background & Aims: There are few in vitro models for studying the 3-dimensional interactions among different liver cell types during organogenesis or disease development. We aimed to generate hepatic organoids that comprise different parenchymal liver cell types and have structural features of the liver, using human pluripotent stem cells.

Methods: We cultured H1 human embryonic stem cells (WA-01, passage 27-40) and induced pluripotent stem cells (GM23338) with a series of chemically defined and serum-free media to induce formation of posterior foregut cells, which were differentiated in 3 dimensions into hepatic endoderm spheroids and stepwise into hepatoblast spheroids.

A Chemically Defined Feeder-free System for the Establishment and Maintenance of the Human Naive Pluripotent State.

The distinct states of pluripotency in the pre- and post-implantation embryo can be captured in vitro as naive and primed pluripotent stem cell cultures, respectively. The study and application of the naive state remains hampered, particularly in humans, partially due to current culture protocols relying on extraneous undefined factors such as feeders. Here we performed a small-molecule screen to identify compounds that facilitate chemically defined establishment and maintenance of human feeder-independent naive embryonic (FINE) stem cells.

Midbrain-like Organoids from Human Pluripotent Stem Cells Contain Functional Dopaminergic and Neuromelanin-Producing Neurons.

Recent advances in 3D culture systems have led to the generation of brain organoids that resemble different human brain regions; however, a 3D organoid model of the midbrain containing functional midbrain dopaminergic (mDA) neurons has not been reported. We developed a method to differentiate human pluripotent stem cells into a large multicellular organoid-like structure that contains distinct layers of neuronal cells expressing characteristic markers of human midbrain. Importantly, we detected electrically active and functionally mature mDA neurons and dopamine production in our 3D midbrain-like organoids (MLOs).

In Vivo Mapping of Eukaryotic RNA Interactomes Reveals Principles of Higher-Order Organization and Regulation.

Identifying pairwise RNA-RNA interactions is key to understanding how RNAs fold and interact with other RNAs inside the cell. We present a high-throughput approach, sequencing of psoralen crosslinked, ligated, and selected hybrids (SPLASH), that maps pairwise RNA interactions in vivo with high sensitivity and specificity, genome-wide. Applying SPLASH to human and yeast transcriptomes revealed the diversity and dynamics of thousands of long-range intra- and intermolecular RNA-RNA interactions.

Deterministic Restriction on Pluripotent State Dissolution by Cell-Cycle Pathways.

During differentiation, human embryonic stem cells (hESCs) shut down the regulatory network conferring pluripotency in a process we designated pluripotent state dissolution (PSD). In a high-throughput RNAi screen using an inclusive set of differentiation conditions, we identify centrally important and context-dependent processes regulating PSD in hESCs, including histone acetylation, chromatin remodeling, RNA splicing, and signaling pathways. Strikingly, we detected a strong and specific enrichment of cell-cycle genes involved in DNA replication and G2 phase progression.

Klf2 is an essential factor that sustains ground state pluripotency.

The maintenance of mouse embryonic stem cells (mESCs) requires LIF and serum. However, a pluripotent "ground state," bearing resemblance to preimplantation mouse epiblasts, can be established through dual inhibition (2i) of both prodifferentiation Mek/Erk and Gsk3/Tcf3 pathways. While Gsk3 inhibition has been attributed to the transcriptional derepression of Esrrb, the molecular mechanism mediated by Mek inhibition remains unclear.

Induction of a human pluripotent state with distinct regulatory circuitry that resembles preimplantation epiblast.

Human embryonic stem cells (hESCs) are derived from the inner cell mass of the blastocyst. Despite sharing the common property of pluripotency, hESCs are notably distinct from epiblast cells of the preimplantation blastocyst. Here we use a combination of three small-molecule inhibitors to sustain hESCs in a LIF signaling-dependent hESC state (3iL hESCs) with elevated expression of NANOG and epiblast-enriched genes such as KLF4, DPPA3, and TBX3.

PCBP1 suppresses the translation of metastasis-associated PRL-3 phosphatase.

Overexpression of phosphatase of regenerating liver (PRL)-3 is associated with the progression of diverse human cancers. We show that the overexpression of PRL-3 protein is not directly associated with its transcript levels, indicating the existence of an underlying posttranscriptional regulation. The 5' untranslanted region (UTR) of PRL-3 mRNA possesses triple GCCCAG motifs capable of suppressing mRNA translation through interaction with PolyC-RNA-binding protein 1 (PCBP1), which retards PRL-3 mRNA transcript incorporation into polyribosomes.

VHZ is a novel centrosomal phosphatase associated with cell growth and human primary cancers.

Background: VHZ is a VH1-like (member Z) dual specific protein phosphatase encoded by DUSP23 gene. Some of the dual specific protein phosphatases (DSPs) play an important role in cell cycle control and have shown to be associated with carcinogenesis. Here, the expression of VHZ associated with cell growth and human cancers was investigated.