Cloning Analysis Research Articles

Perspectives on Ergodic Cancer Therapy Derived from Cloning Genome Chaos via In Vivo Rhabdomyosarcoma RA-2 Models: a Narrative Review.

This review explores articles concerning the experimental research cycle on genome instability in cell populations of highly malignant recurrent organotropic rhabdomyosarcoma RA- 2 in rats. Clonal analysis and cloning were pivotal components of this research, which relies on the frequency of cells with micronuclei and internuclear bridges to gauge the intensity of chromothripsis and break-fusion-bridge cycles. The efficacy of cloning, determined by these indicators, stemmed from the deliberate isolation of tumor stem cells, yielding clones in which chromothripsis activity and breakage-fusion-bridge cycles were sustained. Notably, it is plausible that the stem cells themselves, progenitors of these clones, harbor dicentric chromosomes and chromosomal fragments, contributing to the formation of "fatal micronuclei" in their karyotype. Cloning based on bridges and micronuclei has proven effective up to a certain threshold (15%-18%), reaffirming the predicted reproductive extinction of malignant cell populations under mutational pressure and genome chaos, as posited by the genetic theory of cell populations. Furthermore, this review highlights the potential of ergodic cancer therapy as a novel therapeutic strategy. Ergodic therapy offers promising prospects for late-stage and terminal malignant tumors, where conventional treatments may fall short due to advanced progression. Furthermore, by "enhancing chromothripsis" through the induction of additional micronuclei and bridges, ergodic cancer therapy seeks to increase genome chaos to a critical threshold, potentially halting malignant progression. This innovative approach presents opportunities to explore new drugs and targets for chromothripsis-based oncotherapy, addressing the pressing need for effective treatments in advanced stages of malignancy.

Spontaneous high clonal expansion of Wilms’ tumor gene 1-specific cytotoxic T-lymphocytes in patients with Wilms’ tumor gene 1-expressing solid tumor

Wilms’ tumor protein 1 (WT1)-targeted immunotherapy has been used in patients with leukemia and solid tumors. However, the spontaneous WT1-specific immune response before WT1 peptide vaccination in patients with WT1-expressing tumors (PTs) remains unclear. Therefore, we investigated whether WT1-specific cytotoxic CD8+ T-lymphocytes (CTLs) are clonally expanded in the peripheral blood outside of tumor sites. Clonal expansion of WT1126 peptide (a.a.126–134)-specific CTLs (WT1126-CTLs) was compared between seven PTs and five healthy volunteers (HVs), and their T-cell receptors (TCRs) were analyzed at the single-cell level. Overall, 433 and 351 TCR β-chains of WT1126-CTLs were detected from PTs and HVs, respectively, and complementarity-determining region 3 was sequenced for clonality analysis. The frequencies of WT1126-CTLs were higher in human leukocyte antigen (HLA)-A*02:01+ PTs than in HLA-A*02:01+ HVs, although the difference was not statistically significant. WT1126-CTLs of differentiated types, including memory and effector, were higher in PTs than in HVs; whereas, those of the naïve type were higher in HVs than in PTs. WT1126-CTL clonality was significantly higher in PTs than in HVs. Furthermore, the frequency of effector WT1126-CTLs positively correlated with WT1126-CTL clonality in PTs; whereas, the frequency of naïve phenotype WT1126-CTLs tended to be negatively correlated with clonality. In conclusion, these results suggest that the WT1 protein in tumor cells is highly immunogenic, thereby stimulating endogenous naïve-type WT1126-CTLs and enabling them to clonally expand and differentiate into effector-type WT1126-CTLs.

Mini and enhanced CRISPR activators for cancer therapies

IntroductionThe RNA-guided nuclease Cas9 can be used as a programmable transcription activator, but there is still room for improvement in its effectiveness in eukaryotes, and its potential in cancer genetic therapy has been poorly investigated. ObjectivesWe aim to construct optimized CRISPRa tools and detect their potential role in cancer therapy by screening 9aa-TAD. MethodsWe selected a range of transcriptional coactivators for programmable activation and analyzed their effects on the expression of multiple endogenous genes using Flow cytometry and qRT-PCR. In order to improve the activation capacity of the CRISPRa tool, we fused the coactivators with the efficient dCas9-VPR system to construct a new activation system. Utilize RNA-seq to assess the activation specificity of genome-wide. To evaluate the value of the newly constructed activation system in cancer gene therapy, we activated the expression of the tumor suppressor genes PER2 and ZNF382, and performed changes in cancer cell proliferation qRT-PCR and clonal formation analysis. ResultsIn this study, we screened the NHR module from C. elegans, which demonstrated a high transcription activation capacity with a compact size compared to VP64. We successfully demonstrated its efficiency in activating endogenous genes in mammalian cells. Furthermore, we developed an enhanced fused variant called NHR-VP64-p65-Rta (NVPR), which showed even higher efficiency compared to the previously established VPR module, making it an effective CRISPRa tool. The dCas9-NVPR complex also exhibited high specificity on a genome-wide scale. Finally, we utilized the dCas9-NVPR tool to restore the expression of tumor suppressor genes PER2 and ZNF382, effectively inhibiting the malignant phenotype of cancer cells. ConclusionWe have successfully developed and demonstrated a breakthrough CRISPRa tool with promising implications for cancer genetic therapy. This innovation expands the range of available gene editing tools and further validates the immense potential of CRISPR-based approaches in precision medicine.

Prevention of possible vancomycin resistant enterococcus outbreak caused by infants transferred due to earthquake-trauma

Infection control measures are disrupted due to the large number of patients admitted in a very short time, in the early post-earthquake period. Inter-hospital or intra-hospital transfers can cause the spread of resistant bacteria. We reported the possible outbreak and its prevention caused by vancomycin-resistant enterococcus (VRE) strains carried by infants transferred from another unit to our neonatal intensive care unit after the earthquake. Screening cultures (rectal swab) were obtained from infants on admission and patients were kept in contact isolation. We studied the clonal analysis of VRE strains isolated from patients by Pulse Field Gel Electroforesis.

Temporal recording of mammalian development and precancer

Temporal ordering of cellular events offers fundamental insights into biological phenomena. Although this is traditionally achieved through continuous direct observations1,2, an alternative solution leverages irreversible genetic changes, such as naturally occurring mutations, to create indelible marks that enables retrospective temporal ordering3–5. Using a multipurpose, single-cell CRISPR platform, we developed a molecular clock approach to record the timing of cellular events and clonality in vivo, with incorporation of cell state and lineage information. Using this approach, we uncovered precise timing of tissue-specific cell expansion during mouse embryonic development, unconventional developmental relationships between cell types and new epithelial progenitor states by their unique genetic histories. Analysis of mouse adenomas, coupled to multiomic and single-cell profiling of human precancers, with clonal analysis of 418 human polyps, demonstrated the occurrence of polyclonal initiation in 15–30% of colonic precancers, showing their origins from multiple normal founders. Our study presents a multimodal framework that lays the foundation for in vivo recording, integrating synthetic or natural indelible genetic changes with single-cell analyses, to explore the origins and timing of development and tumorigenesis in mammalian systems.

Characterization, Antibiotic Susceptibility, and Clonal Analysis of Carbapenem-Resistant Klebsiella pneumoniae From Different Clinical Cases

Characterization, Antibiotic Susceptibility, and Clonal Analysis of Carbapenem-Resistant Klebsiella pneumoniae From Different Clinical Cases

Interleukin-1β modulates lymphoid differentiation of Flt3-positive multipotent progenitors after transplantation

Myeloablative pre-conditioning facilitates the differentiation of transplanted hematopoietic stem and progenitor cells (HSPCs). However, the factors in the stress environment that regulate HSPC behavior remain elusive. Here, we investigated the mechanisms that shaped the cell fates of transplanted murine multipotent progenitors (MPPs) expressing the Fms-related receptor tyrosine kinase 3 gene (Flt3). Using lineage tracing, clonal analysis, and single-cell RNA sequencing (RNA-seq), we showed that the myeloablative environment increased lymphoid priming of Flt3+ MPPs and that their efficient B cell output required intact interleukin 1 (IL-1) signaling. The Flt3+ MPPs with short-term exposure to IL-1β underwent a myeloid-biased to lymphoid-biased cell fate switch and produced more lymphoid-biased progeny with a strongerB lymphopoiesis capacity invitro. Correspondingly, a brief exposure to IL-1β facilitated the B cell output of transplanted Flt3+ MPPs invivo. Together, our study demonstrated an unrecognized function of IL-1β in promoting B lymphopoiesis and highlighted a latent effect of IL-1β in regulating MPP cell fate dynamics.

YAP Overcomes Mechanical Barriers to Induce Mitotic Rounding and Adult Cardiomyocyte Division.

Many specialized cells in adult organs acquire a state of cell cycle arrest and quiescence through unknown mechanisms. Our limited understanding of mammalian cell cycle arrest is derived primarily from cell culture models. Adult mammalian cardiomyocytes, a classic example of cell cycle arrested cells, exit the cell cycle postnatally and remain in an arrested state for the life of the organism. Cardiomyocytes can be induced to re-enter the cell cycle by YAP5SA, an active form of the Hippo signaling pathway effector YAP. We performed clonal analyses to determine the cell kinetics of YAP5SA cardiomyocytes. We also performed single-cell RNA sequencing, marker gene analysis, and functional studies to examine how YAP5SA cardiomyocytes progress through the cell cycle. We discovered that YAP5SA-expressing cardiomyocytes divided efficiently, with >20% of YAP5SA cardiomyocyte clones containing ≥2 cardiomyocytes. YAP5SA cardiomyocytes re-entered cell cycle at the G1/S transition and had an S phase lasting ≈48 hours. Sarcomere disassembly is required for cardiomyocyte progression from S to G2 phase and the induction of mitotic rounding. Although oscillatory Cdk expression was induced in YAP5SA cardiomyocytes, these cells inefficiently progressed through G2 phase. This is improved by inhibiting P21 function, implicating checkpoint activity as an additional barrier to YAP5SA-induced cardiomyocyte division. Our data reveal that YAP5SA overcomes the mechanically constrained myocardial microenvironment to induce mitotic rounding with cardiomyocyte division, thus providing new insights into the in vivo mechanisms that maintain cell cycle quiescence in adult mammals.

Overlapping Gene Expression and Molecular Features in High-Grade B-Cell Lymphoma

Aggressive B-cell lymphoma encompasses Burkitt lymphoma (BL), diffuse large B-cell lymphoma (DLBCL), and, as per the 2016 WHO classification, high-grade B-cell lymphoma (HGBL) not otherwise specified (NOS) and HGBL double/triple hit (DH/TH). However, the diagnostic distinction of HGBL from BL and DLBCL is difficult by means of histology/immunostaining in a substantial number of patients. This study aimed to improve subtyping by the identification of molecular features of aggressive B-cell lymphomas, with a specific focus on HGBL. To this end, we performed a comprehensive gene expression and mutational pattern analysis as well as the detection of B-cell clonality of 34 cases diagnosed with BL (n = 4), DLBCL (n = 16), HGBL DH (n = 8), and HGBL NOS (n = 6). Three distinct molecular subgroups were identified based on gene expression, primarily influenced by MYC expression/translocation and cell proliferation. In HGBL, compared to BL, there was an upregulation of PRKAR2B and TERT. HGBL DH exhibited elevated expression of GAMT and SMIM14, while HGBL NOS showed increased expression of MIR155HG and LZTS1. Our gene mutation analysis revealed MYC, ARID1A, BCL2, KMT2D, and PIM1 as the most affected genes in B-cell lymphoma, with BCL2 and CREBBP predominant in HGBL DH, and MYC and PIM1 in HGBL NOS. Clonality analysis of immunoglobulin heavy and light chain rearrangements did not show distinguishable V- or J-usage between the diagnostic subgroups.

An amphiregulin reporter mouse enables transcriptional and clonal expansion analysis of reparative lung Treg cells.

Regulatory T (Treg) cells are known to play critical roles in tissue repair via provision of growth factors such as amphiregulin (Areg). Areg-producing Treg cells have previously been difficult to study because of an inability to isolate live Areg-producing cells. In this report, we created a novel reporter mouse to detect Areg expression in live cells ( Areg Thy1.1 ). We employed influenza A and bleomycin models of lung damage to sort Areg-producing and -non-producing Treg cells for transcriptomic analyses. Single cell RNA-seq revealed distinct subpopulations of Treg cells and allowed transcriptomic comparisons of damage-induced populations. Single cell TCR sequencing showed that Treg cell clonal expansion is biased towards Areg-producing Treg cells, and largely occurs within damage-induced subgroups. Gene module analysis revealed functional divergence of Treg cells into immunosuppression-oriented and tissue repair-oriented groups, leading to identification of candidate receptors for induction of repair activity in Treg cells. We tested these using an ex vivo assay for Treg cell-mediated tissue repair, identifying 4-1BB agonism as a novel mechanism for reparative activity induction. Overall, we demonstrate that the Areg Thy1.1 mouse is a promising tool for investigating tissue repair activity in leukocytes.

Identification and characterisation of colistin-resistant Acinetobacter colistiniresistens co-producing IMP-1 and OXA-58 carbapenemases

BackgroundCarbapenem-resistant Acinetobacter is of increasing global concern because infections are challenging to treat with standard antibiotics. Here, we identified a previously uncharacterised Acinetobacter sp. clinical isolate as Acinetobacter colistiniresistens co-producing IMP-1 and OXA-58. We also examined expression of genes related to antibiotic susceptibility and drug resistance, including blaIMP. MethodsThe isolate was deposited at the National Institute of Technology and Evaluation (NITE) as Acinetobacter sp. NBRC 110496. Susceptibility was defined according to the Clinical and Laboratory Standards Institute (CLSI) breakpoints. Genomic and clonal analyses were performed to identify species and resistance genes. ResultsThe isolate was resistant to β-lactams, including broad-spectrum cephalosporins and carbapenems, polymyxins, and trimethoprim/sulfamethoxazole. Genomic analysis identified the isolate as A. colistiniresistens harbouring blaIMP-1, blaOXA-58, blaOXA-670, aac(6′)-Ib, aac(6′)-Ij, ant(3”)-II, aph(3’)-VI, msrE, mphE, and sul1. Colistin resistance was associated with the eptA-like gene, which encodes a lipid A-modifying enzyme. SNP-based phylogenetic analysis revealed that the strain clustered with other strains isolated in Japan. The IMP-1/OXA-58-producing strain described in this study has a novel integron structure surrounding blaIMP-1, aacA and sul1. ConclusionsColistin-resistant IMP-1/OXA-58-co-producing A. colistiniresistens was identified in a patient. This isolate could serve as a reservoir for carbapenemase-producing organisms. This study suggests that screening for colistin-resistant isolates is crucial to preserve colistin as a therapeutic agent for multidrug-resistant bacteria. Identification of this MDR isolate in Asia, and the danger of it spreading worldwide, should raise serious concerns.

One decade of point-prevalence surveys for carriage of extended-spectrum beta-lactamase-producing enterobacterales: whole genome sequencing based prevalence and genetic characterization in a large Dutch teaching hospital from 2013 to 2022

ObjectivesTo determine the prevalence, trends, and potential nosocomial transmission events of the hidden reservoir of rectal carriage of extended-spectrum beta-lactamase-producing Enterobacterales (ESBL-E).MethodsFrom 2013 to 2022, yearly point prevalence surveys were conducted in a large Dutch teaching hospital. On the day of the survey, all admitted patients were screened for ESBL-E rectal carriage using peri-anal swabs and a consistent and sensitive selective culturing method. All Enterobacterales phenotypically suspected of ESBL production were analysed using whole genome sequencing for ESBL gene detection and clonal relatedness analysis.ResultsOn average, the ESBL-E prevalence was 4.6% (188/4,119 patients), ranging from 2.1 to 6.6% per year. The ESBL-prevalence decreased on average 5.5% per year. After time trend correction, the prevalence in 2016 and 2020 was lower compared to the other year. Among the ESBL-E, Escherichia coli (80%) and CTX-M genes (85%) predominated. Potential nosocomial transmission events could be found in 5.9% (11/188) of the ESBL-E carriers.ConclusionsThe ESBL-E rectal carriage prevalence among hospitalized patients was 4.6% with a downward trend from 2013 to 2022. The decrease in ESBL-E prevalence in 2020 could have been due to the COVID-19 pandemic and subsequent countrywide measures as no nosocomial transmission events were detected in 2020. However, the persistently low ESBL-E prevalences in 2021 and 2022 suggest that the decline in ESBL-E prevalence goes beyond the COVID-19 pandemic, indicating that overall ESBL-E carriage rates are declining over time. Continuous monitoring of ESBL-E prevalence and transmission rates can aid infection control policy to keep antibiotic resistance rates in hospitals low.

Resistance Genes and Mortality in Carbapenem-resistant Klebsiella pneumoniae Bacteremias: Effects of the COVID-19 Pandemic

Emerging carbapenem-resistant Klebsiella pneumoniae (K. pneumoniae) (CRKP) bacteremias are presenting significant public health risks due to limited treatment options and increased mortality. K. pneumoniae isolates exhibit carbapenem resistance rates that vary from 25% to 50% throughout the European continent, including our country. To assess the characteristics of CRKP bacteremia, a condition that has recently demonstrated an increasing prevalence in our center. We sought to ascertain the resistance rates of isolated strains to antibiotics other than carbapenems, identify the responsible carbapenemase genes, evaluate the efficacy of antibiotics, determine mortality rates, explore clonality among strains, and investigate the influence of the COVID-19 pandemic on all these factors. Retrospective observational study. This study included patients aged 18 and older who had experienced meropenem-resistant K. pneumoniae bacteremia. Meropenem resistance was confirmed by employing the Kirby-Bauer disk diffusion method. Meropenem minimum inhibitory concentration (MIC) levels were determined using the gradient test, while colistin MIC levels were ascertained using the disk elution technique. Carbapenemase genes were evaluated via colony polymerase chain reaction (PCR), and clonality analysis was performed using the arbitrarily primed PCR technique. The study comprised 230 patients, with a mean age of 63.1 ± 15.9 years, of whom 58.7% were male. Oxacillinase-48 (OXA-48) was detected in 74.8% of the patients, New Delhi metallo-beta-lactamase (NDM) in 12.6%, OXA-48 + NDM in 7.8%, and KPC in 4.8%. The 14-day and 30-day mortality rates were 57% and 69.6%, respectively. Multivariate analysis of the 30-day mortality revealed several crucial factors, including bacteremia development in the intensive care unit, the occurrence of bacteremia during the COVID-19 pandemic, polymicrobial bacteremia, the use of indwelling intravenous catheters, a platelet count of ≤ 140,000/μl, procalcitonin levels of ≥ 6 μg/l, and a Charlson comorbidity score ≥ 3. Notably, the OXA-48 and KPC genes were upregulated significantly during the COVID-19 pandemic, while the NDM gene groups were downregulated. Additionally, both 14-day and 30-day mortality rates increased significantly. In this study, the most prevalent carbapenemase gene was OXA-48; however, there has been a recent increase in KPC genes. No dominant epidemic strain was identified through clonality analysis. The clustering rate was 68% before the pandemic, increasing to 85.7% during the pandemic. The significance of infection control measures is underscored by the rise in both clustering and mortality rates during the COVID-19 pandemic.

Mechanisms that clear mutations drive field cancerization in mammary tissue

Oncogenic mutations are abundant in the tissues of healthy individuals, but rarely form tumours1–3. Yet, the underlying protection mechanisms are largely unknown. To resolve these mechanisms in mouse mammary tissue, we use lineage tracing to map the fate of wild-type and Brca1−/−;Trp53−/− cells, and find that both follow a similar pattern of loss and spread within ducts. Clonal analysis reveals that ducts consist of small repetitive units of self-renewing cells that give rise to short-lived descendants. This offers a first layer of protection as any descendants, including oncogenic mutant cells, are constantly lost, thereby limiting the spread of mutations to a single stem cell-descendant unit. Local tissue remodelling during consecutive oestrous cycles leads to the cooperative and stochastic loss and replacement of self-renewing cells. This process provides a second layer of protection, leading to the elimination of most mutant clones while enabling the minority that by chance survive to expand beyond the stem cell-descendant unit. This leads to fields of mutant cells spanning large parts of the epithelial network, predisposing it for transformation. Eventually, clone expansion becomes restrained by the geometry of the ducts, providing a third layer of protection. Together, these mechanisms act to eliminate most cells that acquire somatic mutations at the expense of driving the accelerated expansion of a minority of cells, which can colonize large areas, leading to field cancerization.

The circulation of methicillin-resistant Staphylococcus aureus between humans, horses and the environment at the equine clinic.

We performed a retrospective analysis of MRSA isolates collected at the university equine clinic including clinical isolates from 2008 to 2021 and screening environmental, equine and personnel isolates from 2016. Screening and clinical samples were cultured on Brilliance MRSA 2 and Columbia agar (Oxoid), respectively, with enrichment for environmental samples. Antimicrobial susceptibility was assessed by disc diffusion. All the isolates were characterized by spa typing. Eighteen selected isolates were subjected to WGS with subsequent wgMLST clonal analysis. Among 75 MRSA isolates, five spa types were identified, the majority (n = 67; 89.33%) was t011. All isolates were resistant to cefoxitin and ampicillin and carried the mecA gene. In addition, the isolates were resistant to tetracycline (n = 74; 98.67%), gentamicin (n = 70; 93.33%), enrofloxacin (n = 54; 72.00%), sulfamethoxazole-trimethoprim (n = 5; 6.67%) and lincomycin (n = 3; 4.00%) with corresponding genetic markers for the resistance detected in the sequenced isolates. All 18 sequenced isolates belonged to ST398, 16 carried SCCmec type IVa and two carried SCCmec type Vc (5C2&5). Further, isolates carried aur, hlgA, hlgB and hlgC virulence genes, and five isolates carried sak and scn genes, which are part of the immune evasion cluster. Close genetic relatedness was found between isolates from the staff of the clinic and clinical samples of horses. Repeated introduction and long-term persistence of the equine LA-MRSA subclone (ST398-MRSA-IVa/Vc(5C2&5), t011) among the infected horses at the equine clinic with the colonization of personnel, and the environment contamination that might contribute to transmission were observed.

Participation of ventricular trabeculae in neonatal cardiac regeneration leads to ectopic recruitment of Purkinje-like cells.

Unlike adult mammals, newborn mice can regenerate a functional heart after myocardial infarction; however, the precise origin of the newly formed cardiomyocytes and whether the distal part of the conduction system (the Purkinje fiber (PF) network) is properly formed in regenerated hearts remains unclear. PFs, as well as subendocardial contractile cardiomyocytes, are derived from trabeculae, transient myocardial ridges on the inner ventricular surface. Here, using connexin 40-driven genetic tracing, we uncover a substantial participation of the trabecular lineage in myocardial regeneration through dedifferentiation and proliferation. Concomitantly, regeneration disrupted PF network maturation, resulting in permanent PF hyperplasia and impaired ventricular conduction. Proliferation assays, genetic impairment of PF recruitment, lineage tracing and clonal analysis revealed that PF network hyperplasia results from excessive recruitment of PFs due to increased trabecular fate plasticity. These data indicate that PF network hyperplasia is a consequence of trabeculae participation in myocardial regeneration.

Repeated Omicron exposures redirect SARS-CoV-2-specific memory B cell evolution toward the latest variants.

Immunological imprinting by ancestral SARS-CoV-2 strains is thought to impede the robust induction of Omicron-specific humoral responses by Omicron-based booster vaccines. Here, we analyzed the specificity and neutralization activity of memory B (Bmem) cells after repeated BA.5 exposure in individuals previously imprinted by ancestral strain-based mRNA vaccines. After a second BA.5 exposure, Bmem cells with BA.5 spike protein-skewed reactivity were promptly elicited, correlating with preexisting antibody titers. Clonal lineage analysis identified BA.5-skewed Bmem cells that had redirected their specificity from the ancestral strain to BA.5 through somatic hypermutations. Moreover, Bmem cells with redirected BA.5 specificity exhibited accelerated development compared with de novo Bmem cells derived from naïve repertoires. This redirected BA.5 specificity demonstrated greater resilience to viral point mutation and adaptation to recent Omicron variants HK.3 and JN.1, months after the second BA.5 exposure, suggesting that existing Bmem cells elicited by older vaccines can redirect their specificity toward newly evolving variants.

Clonal Analysis and Genetic Diversity of Cat Breeds From Both Local and Foreign Breeds

Clonal Analysis and Genetic Diversity of Cat Breeds From Both Local and Foreign Breeds

Abstract We019: YAP Overcomes Mechanical Barriers to Induce Adult Cardiomyocyte Division

Adult mammalian cardiomyocytes (CMs) are among the least able to renew of all cell types. CMs exit the cell cycle soon after birth and remain cell cycle arrested by unknown mechanisms. We previously found that in adult CMs, the active form of the Hippo signaling pathway effector YAP, YAP5SA, induces cell division in vivo . Here, we analyze the mechanism by which YAP5SA regulates the cell cycle in adult CMs. YAP5SA-expressing adult CMs reenter the cell cycle at the G1/S transition and have a prolonged S-phase lasting approximately 48 hours. Molecular and functional analysis revealed that progression from S to G2 phase, and the induction of mitotic rounding, requires sarcomere disassembly. Transition from G2 to M phase requires overcoming DNA damage checkpoint facilitated by the activation of the P21 degradation pathway. Clonal analysis showed that approximately 20% of CMs progress through cytokinesis. Our results show that multiple barriers are involved in suppressing the adult CM cell cycle. These include the structural block caused by the highly structured CM cytoskeleton and the P21 regulated DNA damage checkpoint.

Landscape of Concomitant Driver Alterations in Classical EGFR-Mutated Non-Small Cell Lung Cancer.

Next-generation sequencing (NGS) has enabled the detection of concomitant driver alterations in non-small cell lung cancer (NSCLC). However, the magnitude and clinical relevance of concomitant drivers remain to be explored. We profiled concomitant driver alterations of EGFR+ NSCLC by using targeted NGS. The associated genomic and clinical features were analyzed and validated in an independent The Cancer Genome Atlas cohort of patients with EGFR+ NSCLC. Out of the total patient population, 334 patients had EGFR mutations along with concomitant driver mutations, comprising 3.09% of the entire cohort. The most frequent co-occurring mutations with sensitizing EGFR mutations include KRAS at 53.9%, followed by ERBB2 at 24.3%, MET at 16.5%, and BRAF at 3.3%. KRAS mutations in concomitant drivers were frequently hyperexchange mutations (25.6% v 8.2%, P < .001), compared with KRAS single drivers. EGFR/ERBB2 drivers exhibited a higher incidence of ERBB2 amplification (40.7% v 16.5%, P < .001) and p.S310F/Y mutations (44.4% v 4.3%, P < .001) compared with ERBB2 alone. EGFR/MET drivers had a higher frequency of MET amplification (71.4% v 43.3%) than MET single drivers. At the genomic level, the median number of additional concurrent mutations was four, with TSC2 (4%), CD274 (1%), and TP53 (63%) being the most frequently coaltered genes in concomitant driver tumors. Interestingly, clonality analysis indicated that EGFR mutations were more likely to occur as clonal events, whereas the codrivers were more often subclonal. Patients with concomitant drivers or with concomitant MET amplification exhibited worse prognosis. These findings might aid in the selection of effective therapeutic regimens and facilitate the development of combination therapies.