Androgenesis-Based Doubled Haploidy: Past, Present, and Future Perspectives

Androgenesis, which entails cell fate redirection within the microgametophyte, is employed widely for genetic gain in plant breeding programs. Moreover, androgenesis-responsive species provide tractable systems for studying cell cycle regulation, meiotic recombination, and apozygotic embryogenesis within plant cells. Past research on androgenesis has focused on protocol development with emphasis on temperature pretreatments of donor plants or floral buds, and tissue culture optimization because androgenesis has different nutritional requirements than somatic embryogenesis. Protocol development for new species and genotypes within responsive species continues to the present day, but slowly. There is more focus presently on understanding how protocols work in order to extend them to additional genotypes and species. Transcriptomic and epigenetic analyses of induced microspores have revealed some of the cellular and molecular responses required for or associated with androgenesis. For example, microRNAs appear to regulate early microspore responses to external stimuli; trichostatin-A, a histone deacetylase inhibitor, acts as an epigenetic additive; ά-phytosulfokine, a five amino acid sulfated peptide, promotes androgenesis in some species. Additionally, present work on gene transfer and genome editing in microspores suggest that future endeavors will likely incorporate greater precision with the genetic composition of microspores used in doubled haploid breeding, thus likely to realize a greater impact on crop improvement. In this review, we evaluate basic breeding applications of androgenesis, explore the utility of genomics and gene editing technologies for protocol development, and provide considerations to overcome genotype specificity and morphogenic recalcitrance in non-model plant systems.

HBI-8000, HUYABIO Lead Clinical Program, Is a Selective Histone Deacetylase Inhibitor With Therapeutic Benefits in Leukemia and in Solid Tumors

HBI-8000 is a small molecule inhibitor of class I HDACs and has been approved for the treatment of PTCL, ATL and, in combination with exemestane, in a subpopulation of breast cancer. Given the roles of HDACs in normal and cancerous cells, there are currently multiple clinical trials, by HUYABIO International, to test the efficacy of HBI-8000 in monotherapy or in combination settings in leukemias and in solid tumors. The current review is focused on the applications of HDACi HBI-8000 in cancer therapy and its potential in combination with DDR agents.

Histone deacetylase inhibitor overrides the effect of soft hydrogel on the mechanoresponse of human mesenchymal stem cells

Human Mesenchymal cells (hMSCs) are promising in regenerative medicine for their multi-lineage differentiation capability. It has been demonstrated that lineage specification is governed by both chemical and mechanical cues. Among all the different mechanical cues known to control hMSCs fate, substrate stiffness is the most well-studied. It has been shown that the naive mesenchymal stem cells when cultured on soft gel, they commit towards adipogenic lineage while when cultured on stiff gel they become osteogenic. Soft substrates also cause less cell spreading, less traction, less focal adhesion assembly and stress fibre formation. Furthermore, chromatin condensation increases when cells are cultured on soft substrates. As the nucleus has been postulated to be mechanosensor and mechanotransducer, in this paper we asked the question how mechanosensing and mechanoresponse process will be influenced if we change the chromatin condensation by using an external chemical stimulus. To address this question, we treated hMSCs cultured on soft polyacrylamide (PA) gels with a histone deacetylase inhibitor (HDACi) called Valproic Acid (VA) which decondense the chromatin by hyperacetylation of histone proteins. We found that the treatment with VA overrides the effect of soft substrates on hMSCs morphology, cellular traction, nuclear localization of mechnosensory protein YAP, and differentiation. VA treated cells behaved as if they are on stiff substrates in all aspects tested here. Furthermore, we have shown that VA controls hMSCs differentiation via activation of ERK/MAPK pathway by increasing the p-ERK expression which inhibits adipogenic differentiation potential of mesenchymal stem cells. Collectively, these findings for the first time demonstrate that inhibiting histone acetylation can override the mechanoresponse of hMSCs. This work will help us to fundamentally understand the mechanosignalling process and to control the hMSCs differentiation in tissue engineering and regenerative medicine.

Rutin Protects from Destruction by Interrupting the Pathways Playing a Role in the Possible Damage Mechanism of Sodium Valproate in the Liver and Kidney Tissues of Rats

Background: The present study investigated the effects of rutin (RUT), which has various biological and pharmacological properties, on liver and kidney damage caused by histone deacetylase inhibitor valproic acid (VLP), which is used in the treatment of many psychiatric disorders.Methods and Results: In the study, 50 or 100 mg/kg RUT treatment was administered 30 minutes after 500 mg/kg VLP was given to rats for 14 days. Then, some pathways that may be involved in the damage mechanism of VLP in liver and kidney tissues were investigated using biochemical, RT-PCR and Western blotting techniques. The results show that the levels of MDA induced by VLP in liver and kidney tissues decreased after RUT treatment, and the levels of SOD, CAT, GPx and GSH suppressed by VLP increased after RUT administration. It was observed that ER stress induced by oxidative stress was alleviated by suppressing the expressions of ATF-6, PERK, IRE1 and GRP78 after RUT treatment. It was observed that the expressions of NF-kB, TNF-a, IL-6, JAK2 and STAT3 in the inflammatory pathway increased after VLP administration, while RUT treatment decreased the levels of these markers. It is also among the data obtained that the levels of markers that play a role in the regulation of apoptosis (Bax, Bcl-2, kaspaz-3, pERK, pJNK) or autophagy (Beclin-1, LC3A, LC3B) approach the control group after RUT treatment.Conclusions: Taken together, it was determined that RUT treatment protected against liver and kidney damage by attenuating VLP-induced oxidative stress, ER stress, inflammation, apoptosis and autophagy.

Crossing of the Cystic Barriers of Toxoplasma gondii by the Fluorescent Coumarin Tetra-Cyclopeptide

FR235222 is a natural tetra-cyclopeptide with a strong inhibition effect on histone deacetylases, effective on mammalian cells as well as on intracellular apicomplexan parasites, such as Toxoplasma gondii, in the tachyzoite and bradyzoite stages. This molecule is characterized by two parts: the zinc-binding group, responsible for the binding to the histone deacetylase, and the cyclic tetrapeptide moiety, which plays a crucial role in cell permeability. Recently, we have shown that the cyclic tetrapeptide coupled with a fluorescent diethyl-amino-coumarin was able to maintain properties of cellular penetration on human cells. Here, we show that this property can be extended to the crossing of the Toxoplasma gondii cystic cell wall and the cell membrane of the parasite in its bradyzoite form, while maintaining a high efficacy as a histone deacetylase inhibitor. The investigation by molecular modeling allows a better understanding of the penetration mechanism.

Vorinostat, a Histone Deacetylase Inhibitor, as a Candidate Therapy to Treat Liver Pathology in a Niemann-Pick type C Disease Mouse Model

<p>Niemann-Pick type C (NPC) disease is a rare neuro-visceral, lysosomal storage disorder for which no effective therapy yet exists. A recessive mutation in the late endosomal/lysosomal cholesterol transport genes NPC1 (95%) or NPC2 (5%) are the causative factors which leads to an accumulation of unesterified cholesterol and sphingolipids in the late endosome/lysosome. It is a build-up of these lipids that, in the majority of cases, ultimately leads to premature death prior to adolescence. In recent years, an imbalance of histone acetylation in a yeast model of NPC disease and subsequently an increased expression of histone deacetylase genes in NPC patient fibroblasts relative to healthy controls was discovered. This led to the finding that Vorinostat (suberoylanilide hydroxamic acid (SAHA); Zolinza®) a histone deacetylase inhibitor (HDACi) drug, rescued unesterified cholesterol accumulation in NPC patient fibroblasts. From these findings in NPC patient fibroblasts, a Phase I clinical trial testing the efficacy of orally-administered Vorinostat in adult NPC disease patients commenced in 2014; however, the therapeutic efficacy of Vorinostat in a whole animal model of NPC disease has not been investigated and is thus unknown. In this thesis, the therapeutic efficacy of intra-peritoneal administered 150 mg/kg Vorinostat in the Npc1nmf164 mouse was explored. This internationally approved HDACi reduced liver disease by decreasing lipid accumulation without increasing expression of NPC1; however, the treatment did not delay weight loss, onset of ataxia and premature death, possibly due to insufficient concentrations penetrating through the blood brain barrier. Transcriptome analysis suggested Vorinostat improved liver disease in a pleiotropic manner, not surprising given the epigenetic nature of HDACi at the gene expression level. Overall, the results herein are of particular importance to the current clinical trial where the therapeutic efficacy is being investigated without any knowledge of efficacy in an animal of NPC disease.</p>