Microphysiological stem cell models of the human heart.

Models of heart disease and drug responses are increasingly based on human pluripotent stem cells (hPSCs) since their ability to capture human heart (dys-)function is often better than animal models. Simple monolayer cultures of hPSC-derived cardiomyocytes, however, have shortcomings. Some of these can be overcome using more complex, multi cell-type models in 3D.

CDC7-independent G1/S transition revealed by targeted protein degradation.

The entry of mammalian cells into the DNA synthesis phase (S phase) represents a key event in cell division. According to current models of the cell cycle, the kinase CDC7 constitutes an essential and rate-limiting trigger of DNA replication, acting together with the cyclin-dependent kinase CDK2. Here we show that CDC7 is dispensable for cell division of many different cell types, as determined using chemical genetic systems that enable acute shutdown of CDC7 in cultured cells and in live mice.

PAX7 Balances the Cell Cycle Progression via Regulating Expression of and in Differentiating PSCs.

PAX7 transcription factor plays a crucial role in embryonic myogenesis and in adult muscles in which it secures proper function of satellite cells, including regulation of their self renewal. PAX7 downregulation is necessary for the myogenic differentiation of satellite cells induced after muscle damage, what is prerequisite step for regeneration. Using differentiating pluripotent stem cells we documented that the absence of functional PAX7 facilitates proliferation.

Cell cycle regulation of embryonic stem cells and mouse embryonic fibroblasts lacking functional Pax7.

The transcription factor Pax7 plays a key role during embryonic myogenesis and in adult organisms in that it sustains the proper function of satellite cells, which serve as adult skeletal muscle stem cells. Recently we have shown that lack of Pax7 does not prevent the myogenic differentiation of pluripotent stem cells. In the current work we show that the absence of functional Pax7 in differentiating embryonic stem cells modulates cell cycle facilitating their proliferation.

MEK1 is required for the development of NRAS-driven leukemia.

The dual-specificity kinases MEK1 and MEK2 act downstream of RAS/RAF to induce ERK activation, which is generally considered protumorigenic. Activating MEK mutations have not been discovered in leukemia, in which pathway activation is caused by mutations in upstream components such as RAS or Flt3. The anti-leukemic potential of MEK inhibitors is being tested in clinical trials; however, downregulation of MEK1 promotes Eμ-Myc-driven lymphomagenesis and MEK1 ablation induces myeloproliferative disease in mice, raising the concern that MEK inhibitors may be inefficient or counterproductive in this context.

Epidermal RAF prevents allergic skin disease.

The RAS pathway is central to epidermal homeostasis, and its activation in tumors or in Rasopathies correlates with hyperproliferation. Downstream of RAS, RAF kinases are actionable targets regulating keratinocyte turnover; however, chemical RAF inhibitors paradoxically activate the pathway, promoting epidermal proliferation. We generated mice with compound epidermis-restricted BRAF/RAF1 ablation.

Adaptation of PCR technique for quantitative estimation of genetic material from different regions of chromosome 21 in cases of trisomy 21.

Pre- and postnatal diagnosis of chromosomal aberrations is generally based on conventional cytogenetic analysis. In this paper, we have devised a quantitative polymerase chain reaction (Q-PCR) method to determine gene dose effects and applied it in cases of regular trisomy 21 as a model. The method is based on quantitative assessment of PCR products after using primers amplifying DNA fragments located in the pericentromeric, heterochromatic, euchromatic and telomeric regions of chromosome 21.

The dog genome map and its use in mammalian comparative genomics.

The dog genome organization was extensively studied in the last ten years. The most important achievements are the well-developed marker genome maps, including over 3200 marker loci, and a survey of the DNA genome sequence. This knowledge, along with the most advanced map of the human genome, turned out to be very useful in comparative genomic studies.

Inv(10) in a patient with hypogonadotropic hypogonadism.

Hypogonadotropic hypogonadism (HH) was diagnosed in a 22-year-old patient with 46,XY,inv(10) karyotype. It may be associated with some gene mutations of chromosome X, (KAL-1: Kallman syndrome; and DAX-1: congenital adrenal hypoplasia), as well as of certain autosomes, including chromosome 10. This study aimed to: (1) elucidate the aetiopathogenesis of the disease in the studied case: (2) diagnose chromosome aberrations as accurately as possible: and (3) determine if the observed clinical picture can be referred to the diagnosed chromosomal aberration or it is a mere coincidence.

Prenatal detection of maternal UPD15 in a new case with i(15p) by Timing Replication Test (TRT) and methylation analysis.

DNA replication kinetics of the Prader-Willi/Angelman Critical Region (PWACR) was studied with and without synchronisation in human amniotic cell cultures obtained from 20 cases with normal karyotype and 4 cases with a marker of chromosome 15, respectively. A Timing Replication Test (TRT) was performed by synchronisation of amniotic cell cultures and followed by interphase FISH to analyse and compare the early/late replication patterns in SNRPN and UBE3A genes between the homologues of chromosome 15. Asynchronous replication patterns of the analysed genes were observed in both amniotic cell cultures but the percentage of interphase nuclei presenting with asynchronous replication was significantly increased in the cultures with synchronisation (40-51%), as compared to those without synchronisation (20-23%).

[Detection of chromosomal aneuploidies in fetus by multiplex Q-PCR method].

With application of the quantitative PCR, Q-PCR, two cases of aneuploidy: trisomy 18 and trisomy 21 were detected in the course of routine prenatal diagnosis in amniotic cells DNA obtained from 1.5 ml of the amniotic fluid. The conventional cytogenetic methods confirmed the diagnosis and the following karyotypes were established: 47,XY,+21 and 47,XX,+13.