Megakaryocytes and hepatocytes are unique cells in mammals that undergo polyploidization through endomitosis in terminal differentiation.Many polyploidization regulators and underlying mechanisms have been reported,mo...Megakaryocytes and hepatocytes are unique cells in mammals that undergo polyploidization through endomitosis in terminal differentiation.Many polyploidization regulators and underlying mechanisms have been reported,most of which are tightly coupled with development,organogenesis,and cell differentiation.However,the nature of endomitosis,which involves successful entry into and exit from mitosis without complete cytokinesis,has not yet been fully elucidated.We highlight that endomitosis is a new cell fate in the cell cycle,and tetraploidy is a critical stage at the bifurcation of cell fate decision.This review summarizes the recent research progress in this area and provides novel insights into how cells manipulate mitosis toward endomitosis.Endomitotic cells can evade the tetraploidy restrictions and proceed to multiple rounds of the cell cycle.This knowledge not only deepens our understanding of endomitosis as a fundamental biological process but also offers new perspectives on the physiological and pathophysiological implications of polyploidization.展开更多
The present comparative review discusses conservation of early evolutionary, relic genetics in the genome of man, which determine two different mechanistic reductive division systems expressed by normal, human diploid...The present comparative review discusses conservation of early evolutionary, relic genetics in the genome of man, which determine two different mechanistic reductive division systems expressed by normal, human diploid cells. The divisions were orderly and segregated genomes reductively to near-diploid daughter cells, which showed gain of a proliferative advantage (GPA) over cells of origin. This fact of GPA expression is a fundamental requirement for initiation of tumorigenesis. The division systems were responses to a carcinogen-free induction system, consisting of short (1 - 3 days) exposures of young cells to nutritional deprivation of amino acid glutamine (AAD). In recovery growth (2 - 4 days) endo-tetra/ochtoploid cells and normal diploid metaphase cells demonstrated chromosomal reductive divisions to respectively heterozygous and homozygous altered daughter cells. Both division systems showed co-segregating whole complements, which for reduction of the diploid metaphases could only arise from gonomeric-based autonomous behavior of maternal and paternal (mat/pat) genomes. The timely associated appearance with these latter divisions was fast growing small-cells (1/2 volume-size reduced from normal diploidy), which became homozygous from haploid, genomic doubling. Both reductive divisions thus produced genome altered progeny cells with GPA, which was associated with pre-cancer-like cell-phenotypic changes. Since both “undesirable” reductive divisions expressed orderly division sequences, their genetic controls were assumed to be “old genetics”, evolutionarily conserved in the genome of man. Support for this idea was a search for evidential material in the evolutionary record from primeval time, when haploid organisms were established. The theory was that endopolyploid and gonomery-based reductive divisions relieved the early eukaryotic organisms from accidental, non-proliferative diploidy and polyploidy, bringing the organism back to vegetative haploid proliferation. Asexual cycles were common for maintenance of propagating haploid and diploid early unicellular eukaryotes. Reduction of accidental diploidy was referred to as “one-step meiosis” which meant gonomeric-based maternal and paternal genomic independent segregations. This interpretation was supported by exceptional chromosomal behaviors. However, multiple divisions expressing non-disjunction was the choice-explanation from evolutionists, which today is also suggested for the rarer LL-1 near haploid leukemia. These preserved non-mitotic mechanistic divisions systems are today witnessed in apomixes and parthenogenesis in many animal phyla. Thus, the indications are the modern genome of man harbors, relic-genetics from past “good” evolvements assuring “stable” proliferation of ancient, primitive eukaryotes, but with cancer-like effects for normal human cells.展开更多
Cancers in young children in early growing age was a short PBS (KQED) report (11/21/2014), but without informational source, which prompted a Google search. Sports-associated injuries with medical healing treatments c...Cancers in young children in early growing age was a short PBS (KQED) report (11/21/2014), but without informational source, which prompted a Google search. Sports-associated injuries with medical healing treatments concluded that there were no association between these body traumas and cancer development. But there are other activities from young children, such as “dare-devil” skateboard and bicycling meter-high jumping with potential high energy falls, to serious broken-bone injuries. Falls of children are among the most common causes of US emergency response. The question is why bodily injury is associated with cancer-development? An answer to this question was exemplified by osteosarcoma in young children, which suggested that injury to growing points of bone and surrounding soft tissue cells would elicit a repair process (wound healing process) producing polyploidy with diplochromosomes. The non-mitotic reductive division of such 4-chromatid chromosomes has been shown?in vitro?to produce pathological cancer-like phenotypes, including gain of a proliferative advantage.展开更多
Silk gland cells of silkworm larvae undergo multiple cycles of endomitosis for the synthesis of silk proteins during the spinning phase. In this paper, we analyzed the endomitotic DNA synthesis of silk gland cells dur...Silk gland cells of silkworm larvae undergo multiple cycles of endomitosis for the synthesis of silk proteins during the spinning phase. In this paper, we analyzed the endomitotic DNA synthesis of silk gland cells during larval development, and found that it was a periodic fluctuation, increasing during the vigorous feeding phase and being gradually inhibited in the next molting phase. That means it might be activated by a self- regulating process after molting. The expression levels of cyclin E, cdtl and pcna were consistent with these developmental changes. Moreover, we further examined whether these changes in endomitotic DNA synthesis resulted from feeding or hormonal stimulation. The results showed that DNA synthesis could be inhibited by starvation and re-activated by re-feeding, and therefore appears to be dependent on nutrition. DNA synthesis was suppressed by in vivo treatment with 20-hydroxyecdysone （20E）. However, there was no effect on DNA synthesis by in vitro 20E treatment or by either in vivo or in vitro juvenile hormone treatment. The levels of Akt and 4E-BP phosphorylation in the silk glands were also reduced by starvation and in vivo treatment with 20E. These results indicate that the activation of endomitotic DNA synthesis during the intermolt stages is related to feeding and DNA synthesis is inhibited indirectly by 20E.展开更多
基金supported by the National Natural Science Foundation of China(Nos.32270643,91957109,and 81870427).
文摘Megakaryocytes and hepatocytes are unique cells in mammals that undergo polyploidization through endomitosis in terminal differentiation.Many polyploidization regulators and underlying mechanisms have been reported,most of which are tightly coupled with development,organogenesis,and cell differentiation.However,the nature of endomitosis,which involves successful entry into and exit from mitosis without complete cytokinesis,has not yet been fully elucidated.We highlight that endomitosis is a new cell fate in the cell cycle,and tetraploidy is a critical stage at the bifurcation of cell fate decision.This review summarizes the recent research progress in this area and provides novel insights into how cells manipulate mitosis toward endomitosis.Endomitotic cells can evade the tetraploidy restrictions and proceed to multiple rounds of the cell cycle.This knowledge not only deepens our understanding of endomitosis as a fundamental biological process but also offers new perspectives on the physiological and pathophysiological implications of polyploidization.
文摘The present comparative review discusses conservation of early evolutionary, relic genetics in the genome of man, which determine two different mechanistic reductive division systems expressed by normal, human diploid cells. The divisions were orderly and segregated genomes reductively to near-diploid daughter cells, which showed gain of a proliferative advantage (GPA) over cells of origin. This fact of GPA expression is a fundamental requirement for initiation of tumorigenesis. The division systems were responses to a carcinogen-free induction system, consisting of short (1 - 3 days) exposures of young cells to nutritional deprivation of amino acid glutamine (AAD). In recovery growth (2 - 4 days) endo-tetra/ochtoploid cells and normal diploid metaphase cells demonstrated chromosomal reductive divisions to respectively heterozygous and homozygous altered daughter cells. Both division systems showed co-segregating whole complements, which for reduction of the diploid metaphases could only arise from gonomeric-based autonomous behavior of maternal and paternal (mat/pat) genomes. The timely associated appearance with these latter divisions was fast growing small-cells (1/2 volume-size reduced from normal diploidy), which became homozygous from haploid, genomic doubling. Both reductive divisions thus produced genome altered progeny cells with GPA, which was associated with pre-cancer-like cell-phenotypic changes. Since both “undesirable” reductive divisions expressed orderly division sequences, their genetic controls were assumed to be “old genetics”, evolutionarily conserved in the genome of man. Support for this idea was a search for evidential material in the evolutionary record from primeval time, when haploid organisms were established. The theory was that endopolyploid and gonomery-based reductive divisions relieved the early eukaryotic organisms from accidental, non-proliferative diploidy and polyploidy, bringing the organism back to vegetative haploid proliferation. Asexual cycles were common for maintenance of propagating haploid and diploid early unicellular eukaryotes. Reduction of accidental diploidy was referred to as “one-step meiosis” which meant gonomeric-based maternal and paternal genomic independent segregations. This interpretation was supported by exceptional chromosomal behaviors. However, multiple divisions expressing non-disjunction was the choice-explanation from evolutionists, which today is also suggested for the rarer LL-1 near haploid leukemia. These preserved non-mitotic mechanistic divisions systems are today witnessed in apomixes and parthenogenesis in many animal phyla. Thus, the indications are the modern genome of man harbors, relic-genetics from past “good” evolvements assuring “stable” proliferation of ancient, primitive eukaryotes, but with cancer-like effects for normal human cells.
文摘Cancers in young children in early growing age was a short PBS (KQED) report (11/21/2014), but without informational source, which prompted a Google search. Sports-associated injuries with medical healing treatments concluded that there were no association between these body traumas and cancer development. But there are other activities from young children, such as “dare-devil” skateboard and bicycling meter-high jumping with potential high energy falls, to serious broken-bone injuries. Falls of children are among the most common causes of US emergency response. The question is why bodily injury is associated with cancer-development? An answer to this question was exemplified by osteosarcoma in young children, which suggested that injury to growing points of bone and surrounding soft tissue cells would elicit a repair process (wound healing process) producing polyploidy with diplochromosomes. The non-mitotic reductive division of such 4-chromatid chromosomes has been shown?in vitro?to produce pathological cancer-like phenotypes, including gain of a proliferative advantage.
基金This work was supported by the National Natural Science Foundation of China （Nos. 31172269 and 31272505）, and the Specialized Research Fund for the Doctoral Program of Higher Education （No. 20120182110010）.
文摘Silk gland cells of silkworm larvae undergo multiple cycles of endomitosis for the synthesis of silk proteins during the spinning phase. In this paper, we analyzed the endomitotic DNA synthesis of silk gland cells during larval development, and found that it was a periodic fluctuation, increasing during the vigorous feeding phase and being gradually inhibited in the next molting phase. That means it might be activated by a self- regulating process after molting. The expression levels of cyclin E, cdtl and pcna were consistent with these developmental changes. Moreover, we further examined whether these changes in endomitotic DNA synthesis resulted from feeding or hormonal stimulation. The results showed that DNA synthesis could be inhibited by starvation and re-activated by re-feeding, and therefore appears to be dependent on nutrition. DNA synthesis was suppressed by in vivo treatment with 20-hydroxyecdysone （20E）. However, there was no effect on DNA synthesis by in vitro 20E treatment or by either in vivo or in vitro juvenile hormone treatment. The levels of Akt and 4E-BP phosphorylation in the silk glands were also reduced by starvation and in vivo treatment with 20E. These results indicate that the activation of endomitotic DNA synthesis during the intermolt stages is related to feeding and DNA synthesis is inhibited indirectly by 20E.
