A Whole Genome-Wide Arrayed CRISPR Screen in Primary Organ Fibroblasts to Identify Regulators of Kidney Fibrosis.

Kidney fibrosis presents a hallmark of chronic kidney disease. With ever-increasing patient numbers and limited treatment options available, novel strategies for therapeutic intervention in kidney disease are warranted. Fibrosis commonly results from a wound healing response to repeated or chronic tissue damage, irrespective of the underlying etiology, and can occur in virtually any solid organ or tissue.

Identification of the kinase STK25 as an upstream activator of LATS signaling.

The Hippo pathway maintains tissue homeostasis by negatively regulating the oncogenic transcriptional co-activators YAP and TAZ. Though functional inactivation of the Hippo pathway is common in tumors, mutations in core pathway components are rare. Thus, understanding how tumor cells inactivate Hippo signaling remains a key unresolved question.

The kinases NDR1/2 act downstream of the Hippo homolog MST1 to mediate both egress of thymocytes from the thymus and lymphocyte motility.

The serine and threonine kinase MST1 is the mammalian homolog of Hippo. MST1 is a critical mediator of the migration, adhesion, and survival of T cells; however, these functions of MST1 are independent of signaling by its typical effectors, the kinase LATS and the transcriptional coactivator YAP. The kinase NDR1, a member of the same family of kinases as LATS, functions as a tumor suppressor by preventing T cell lymphomagenesis, which suggests that it may play a role in T cell homeostasis.

Chromothripsis from DNA damage in micronuclei.

Genome sequencing has uncovered a new mutational phenomenon in cancer and congenital disorders called chromothripsis. Chromothripsis is characterized by extensive genomic rearrangements and an oscillating pattern of DNA copy number levels, all curiously restricted to one or a few chromosomes. The mechanism for chromothripsis is unknown, but we previously proposed that it could occur through the physical isolation of chromosomes in aberrant nuclear structures called micronuclei.

Calibrating genomic and allelic coverage bias in single-cell sequencing.

Artifacts introduced in whole-genome amplification (WGA) make it difficult to derive accurate genomic information from single-cell genomes and require different analytical strategies from bulk genome analysis. Here, we describe statistical methods to quantitatively assess the amplification bias resulting from whole-genome amplification of single-cell genomic DNA. Analysis of single-cell DNA libraries generated by different technologies revealed universal features of the genome coverage bias predominantly generated at the amplicon level (1-10 kb).

Cytokinesis failure triggers hippo tumor suppressor pathway activation.

Genetically unstable tetraploid cells can promote tumorigenesis. Recent estimates suggest that ∼37% of human tumors have undergone a genome-doubling event during their development. This potentially oncogenic effect of tetraploidy is countered by a p53-dependent barrier to proliferation.

Downstream of human NDR kinases: impacting on c-myc and p21 protein stability to control cell cycle progression.

The mammalian genome encodes four members of the NDR/LATS kinase family: NDR1 (STK38), NDR2 (STK38L), LATS1 and LATS2, which are highly conserved from yeast to man. Members of the NDR/LATS kinase family have been implicated in a variety of biological processes ranging from cell division and morphology to apoptosis and tumor suppression. In mammals, LATS1/2 function as central parts of the HIPPO tumor suppressor pathway by restricting the activity of the YAP/TAZ proto-oncogenes.

Human NDR kinases control G(1)/S cell cycle transition by directly regulating p21 stability.

The G(1) phase of the cell cycle is an important integrator of internal and external cues, allowing a cell to decide whether to proliferate, differentiate, or die. Multiple protein kinases, among them the cyclin-dependent kinases (Cdks), control G(1)-phase progression and S-phase entry. With the regulation of apoptosis, centrosome duplication, and mitotic chromosome alignment downstream of the HIPPO pathway components MST1 and MST2, mammalian NDR kinases have been implicated to function in cell cycle-dependent processes.

Differential NDR/LATS interactions with the human MOB family reveal a negative role for human MOB2 in the regulation of human NDR kinases.

MOB proteins are integral components of signaling pathways controlling important cellular processes, such as mitotic exit, centrosome duplication, apoptosis, and cell proliferation in eukaryotes. The human MOB protein family consists of six distinct members (human MOB1A [hMOB1A], -1B, -2, -3A, -3B, and -3C), with hMOB1A/B the best studied due to their putative tumor-suppressive functions through the regulation of NDR/LATS kinases. The roles of the other MOB proteins are less well defined.

Ablation of the kinase NDR1 predisposes mice to the development of T cell lymphoma.

Defective apoptosis contributes to the development of various human malignancies. The kinases nuclear Dbf2-related 1 (NDR1) and NDR2 mediate apoptosis downstream of the tumor suppressor proteins RASSF1A (Ras association domain family member 1A) and MST1 (mammalian Ste20-like kinase 1). To further analyze the role of NDR1 in apoptosis, we generated NDR1-deficient mice.

The MST1 and hMOB1 tumor suppressors control human centrosome duplication by regulating NDR kinase phosphorylation.

Background: Human MST/hSAV/LATS/hMOB tumor suppressor cascades are regulators of cell death and proliferation; however, little is known about other functions of MST/hMOB signaling. Mob1p, one of two MOB proteins in yeast, appears to play a role in spindle pole body duplication (the equivalent of mammalian centrosome duplication). We therefore investigated the role of human MOB proteins in centrosome duplication.

Anchoring of FLT3 in the endoplasmic reticulum alters signaling quality.

The mechanism of cell transformation by Fms-like tyrosine kinase 3 (FLT3) in acute myeloid leukemia (AML) is incompletely understood. The most prevalent activated mutant FLT3 ITD exhibits an altered signaling quality, including strong activation of the STAT5 transcription factor. FLT3 ITD has also been found partially retained as a high-mannose precursor in an intracellular compartment.

NDR kinase is activated by RASSF1A/MST1 in response to Fas receptor stimulation and promotes apoptosis.

Human NDR1 and 2 (NDR1/2) are serine-threonine protein kinases in a subgroup of the AGC kinase family. The mechanisms of physiological NDR1/2 activation and their function remain largely unknown. Here we report that Fas and TNF-alpha receptor stimulation activates human NDR1/2 by promoting phosphorylation at the hydrophobic motif (Thr444/442).

Nuclear Dbf2-related protein kinases (NDRs) in isolated cardiac myocytes and the myocardium: activation by cellular stresses and by phosphoprotein serine-/threonine-phosphatase inhibitors.

The nuclear Dbf2-related protein kinases 1 and 2 (NDR1/2) are closely-related AGC family kinases that are strongly conserved through evolution. In mammals, they are activated inter alia by phosphorylation of an hydrophobic domain threonine-residue [NDR1(Thr-444)/NDR2(Thr-442)] by an extrinsic protein kinase followed by autophosphorylation of a catalytic domain serine-residue [NDR1(Ser-281)/NDR2(Ser-282)]. We examined NDR1/2 expression and regulation in primary cultures of neonatal rat cardiac myocytes and in perfused adult rat hearts.

Mammalian NDR protein kinases: from regulation to a role in centrosome duplication.

The NDR (nuclear Dbf2-related) family of kinases is highly conserved from yeast to human, and has been classified as a subgroup of the AGC group of protein kinases based on the sequence of the catalytic domain. Like all other members of the AGC class of protein kinases, NDR kinases require the phosphorylation of conserved Ser/Thr residues for activation. Importantly, NDR family members have two unique stretches of primary sequence: an N-terminal regulatory (NTR) domain and an insert of several residues between subdomains VII and VIII of the kinase domain.