Abiotic stress regulates expression of galactinol synthase genes post-transcriptionally through intron retention in rice

Expression of the Galactinol synthase genes in rice is regulated through post-transcriptional intron retention in response to abiotic stress and may be linked to Raffinose Family Oligosaccharide synthesis in osmotic perturbation. Galactinol synthase (GolS) is the first committed enzyme in raffinose family oligosaccharide (RFO) synthesis pathway and synthesizes galactinol from UDP-galactose and inositol. Expression of GolS genes has long been implicated in abiotic stress, especially drought and salinity. A non-canonical regulation mechanism controlling the splicing and maturation of rice GolS genes was identified in rice photosynthetic tissue. We found that the two isoforms of Oryza sativa GolS (OsGolS) gene, located in chromosomes 3(OsGolS1) and 7(OsGolS2) are interspersed by conserved introns harboring characteristic premature termination codons (PTC). During abiotic stress, the premature and mature transcripts of both isoforms were found to accumulate in a rhythmic manner for very small time-windows interrupted by phases of complete absence. Reporter gene assay using GolS promoters under abiotic stress does not reflect this accumulation profile, suggesting that this regulation occurs post-transcriptionally. We suggest that this may be due to a surveillance mechanism triggering the degradation of the premature transcript preventing its accumulation in the cell. The suggested mechanism fits the paradigm of PTC-induced Nonsense-Mediated Decay (NMD). In support of our hypothesis, when we pharmacologically blocked NMD, the full-length pre-mRNAs were increasingly accumulated in cell. To this end, our work suggests that a combined transcriptional and post transcriptional control exists in rice to regulate GolS expression under stress. Concurrent detection and processing of prematurely terminating transcripts coupled to repressed splicing can be described as a form of Regulated Unproductive Splicing and Translation (RUST) and may be linked to the stress adaptation of the plant, which is an interesting future research possibility.

Abstract P5-07-04: Not presented

This abstract was not presented at the conference.

Citation Format: Chatterjee S, Basak P, Tan S, Lefort S, Pellacani D, Safneck J, Buchel E, Aparicio S, Eaves CJ, Raouf A. Not presented [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-07-04.

Functional characterization of two myo-inositol-1-phosphate synthase (MIPS) gene promoters from the halophytic wild rice (Porteresia coarctata)

MAIN CONCLUSION

The promoter deletion mutants from second isoform of INO1 (gene-encoding MIPS) from Porteresia coarctata of 932 bp (pPcINO1.2.932) and 793 bp (pPcINO1.2.793) prove to be very efficient as salt/drought stress-inducible promoters, while pPcINO1.2.932 is found to be responsive to cold stress as well. The promoters of the two identified myo-inositol-1-phosphate synthase (INO1) isoforms from salt-tolerant wild rice, Porteresia coarctata (PcINO1.1 and PcINO1.2) have been compared bioinformatically with their counterparts present in the salt-sensitive rice, Oryza sativa. PcINO1.2 promoter was found to be enriched with many abiotic stress-responsive elements, like abscisic acid-responsive elements, MYC-responsive elements, MYB-binding sites, low-temperature stress-responsive elements, and heat-shock elements similar to the ones found in the conserved motifs of the promoters of salt/drought stress-inducible INO1 promoters across Kingdom Planta. To have detailed analysis on the arrangement of cis-acting regulatory elements present in PcINO1 promoters, 5' deletion mutational studies were performed in dicot model plants. Both transient as well as stable transformation methods were used to check the influence of PcINO1 promoter deletion mutants under salt and physiologically drought conditions using β-glucuronidase as the reporter gene. The deletion mutant from the promoter of PcINO1.2 of length 932 bp (pPcINO1.2.932) was found to be significantly upregulated under drought stress and also in cold stress, while another deletion mutant, pPcINO1.2.793 (of 793 bp), was significantly upregulated under salt stress. P. coarctata being a halophytic species, the high inducibility of pPcINO1.2.932 upon exposure to low-temperature stress was an unexpected result.

An evolutionary analysis identifies a conserved pentapeptide stretch containing the two essential lysine residues for rice L-myo-inositol 1-phosphate synthase catalytic activity

A molecular evolutionary analysis of a well conserved protein helps to determine the essential amino acids in the core catalytic region. Based on the chemical properties of amino acid residues, phylogenetic analysis of a total of 172 homologous sequences of a highly conserved enzyme, L-myo-inositol 1-phosphate synthase or MIPS from evolutionarily diverse organisms was performed. This study revealed the presence of six phylogenetically conserved blocks, out of which four embrace the catalytic core of the functional protein. Further, specific amino acid modifications targeting the lysine residues, known to be important for MIPS catalysis, were performed at the catalytic site of a MIPS from monocotyledonous model plant, Oryza sativa (OsMIPS1). Following this study, OsMIPS mutants with deletion or replacement of lysine residues in the conserved blocks were made. Based on the enzyme kinetics performed on the deletion/replacement mutants, phylogenetic and structural comparison with the already established crystal structures from non-plant sources, an evolutionarily conserved peptide stretch was identified at the active pocket which contains the two most important lysine residues essential for catalytic activity.

Abstract P3-04-25: Role of H19, a long non-coding RNA, in development of resistance to endocrine therapy in breast cancer cells

Introduction:

Majority of breast cancer tumors are Estrogen receptor positive (ER+) where antiestrogen therapies (endocrine therapies) are the best therapeutic strategy to treat this type of tumors. However, eventually over 30% of patients will develop resistance to endocrine therapies resulting in disease relapse. We recently showed that the long noncoding RNA, H19, is an estrogen target gene that plays a significant role in estrogen-induced proliferation of the normal and malignant ER+ cells. We therefore hypothesize that H19 expression is also important to the proliferation of endocrine therapy resistant cells. In this study, we examined if estrogen-independent H19 expression is important to the development of endocrine therapy resistance.

Objective:

The overall objective of this project is to use therapy sensitive (MCF-7) and therapy-resistant (LCC9) breast cancer cells as model systems to examine the role of long non-coding RNA H19 in development and maintenance of resistance to endocrine therapy.

Methodology and Results:

We examined the expression of H19 in ER+ breast cancer cells (MCF7) that under the selective pressure of fulvesterant (ICI, ER down regulator) acquire resistance to ICI. We observed that while H19 expression was initially decreased as expected, its expression subsequently increased in the ICI-resistant MCF7 cells. Interestingly, H19 knockdown in MCF7 cells significantly decrease their proliferation as determined by Flowcytometry and made them more sensitive to ICI. We also examined H19 expression in the ICI-resistant LCC9 cells and found that ICI treatment increased H19 expression. Interestingly, H19 knockdown in the LCC9 cells decreased their proliferation and surprisingly made them sensitive to ICI treatment. Previous observations indicate that NOTCH4 receptor (NR4) may be involved in endocrine therapy resistance. Interestingly we found that in presence of ICI, NR4 expression is increased and that forced activation of NR4 markedly increases H19 expression in LCC9 cells.

Conclusion:

Altogether these observations suggest that H19 plays an important role in the development of endocrine therapy resistance and further our understanding of the cellular and molecular mechanisms involved in endocrine therapy resistance. These and similar studies could potentially lead to the development of new therapies to treat therapy resistant tumor cells. Further experiments would reveal if signalling pathways that regulate H19 expression independent of estrogen are useful therapies against endocrine therapy resistant tumors.

Citation Format: Basak P, Chatterjee S, Bhat V, Jin H, Su A, Murphy LC, Raouf A. Role of H19, a long non-coding RNA, in development of resistance to endocrine therapy in breast cancer cells [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-04-25.

Significance of galactinol and raffinose family oligosaccharide synthesis in plants

Abiotic stress induces differential expression of genes responsible for the synthesis of raffinose family of oligosaccharides (RFOs) in plants. RFOs are described as the most widespread D-galactose containing oligosaccharides in higher plants. Biosynthesis of RFOs begin with the activity of galactinol synthase (GolS; EC 2.4.1.123), a GT8 family glycosyltransferase that galactosylates myo-inositol to produce galactinol. Raffinose and the subsequent higher molecular weight RFOs (Stachyose, Verbascose, and Ajugose) are synthesized from sucrose by the subsequent addition of activated galactose moieties donated by Galactinol. Interestingly, GolS, the key enzyme of this pathway is functional only in the flowering plants. It is thus assumed that RFO synthesis is a specialized metabolic event in higher plants; although it is not known whether lower plant groups synthesize any galactinol or RFOs. In higher plants, several functional importance of RFOs have been reported, e.g., RFOs protect the embryo from maturation associated desiccation, are predominant transport carbohydrates in some plant families, act as signaling molecule following pathogen attack and wounding and accumulate in vegetative tissues in response to a range of abiotic stresses. However, the loss-of-function mutants reported so far fail to show any perturbation in those biological functions. The role of RFOs in biotic and abiotic stress is therefore still in debate and their specificity and related components remains to be demonstrated. The present review discusses the biology and stress-linked regulation of this less studied extension of inositol metabolic pathway.

Telomerase reverse transcriptase (TERT) expression and role of vincristine sulfate in mouse model of malignancy related peritoneal ascites: an experimental metastatic condition

AIM

To evaluate the efficacy of intraperitoneal vincristine administration into ascitic sarcoma-180 bearing mice as a model of human malignant ascites regarding various peritoneal/retroperitoneal sarcomatosis, and to evaluate the flowcytometric telomerase reverse transcriptase expression for the diagnostic and prognostic purposes.

METHODS

Present study included disease induction by intraperitoneal homologous ascitic sarcoma-180 transplantation followed by in vivo intraperitoneal drug administration to study mitotic index, flowcytometric cell cycle and telomerase reverse transcriptase expression pattern, erythrosin-B dye exclusion study for malignant cell viability assessment. Besides, in vitro malignant ascite culture in presence and absence of vincristine sulfate and survival study were also taken into consideration.

RESULTS

Intraperitoneal vincristine administration (concentration 0.5 mg/kg body weight) significantly diminished the mitotic index in diseased subjects in comparison to untreated control subjects. Treated group of animals showed increased life span and median survival time. Cell viability assessment during the course of drug administration also revealed gradual depression on cell viability over time. Flowcytometric cell cycle analysis showed a good prognostic feature of chemotherapeutic administration schedule by representing high G2/M phase blocked cells along with reduced telomerase reverse transcriptase positive cells in treated animals.

CONCLUSION

We conclude that long term administration of vincristine sulfate in small doses could be a good pharmacological intervention in case of malignant peritoneal ascites due to sarcomatosis as it indirectly reduced the level of telomerase reverse transcriptase expression in malignant cells by directly regulating cell cycle and simultaneously increased the life expectancy of the diseased subjects.

Probing the association behavior of poly(ethylene glycol)-based amphiphilic comb-like polymer in NaCl solution

The effect of salt on the associative behavior of intramolecular aggregates obtained from poly(ethylene glycol)-based amphiphilic comb-like polymers in aqueous medium at pH 6.2 has been investigated by surface tension, fluorescence probe, dynamic light-scattering, and viscometry techniques. Results reveal that the addition of salt screens the electrostatic repulsion between the charges along the polymer backbone in the aggregates and consequently (1) reduces the surface activity at the air/water interface, (2) leads to the contraction of the polymer backbone, and (3) reduces the hydrodynamic sizes of the aggregates. In contrast, the hydrophobicity of the aggregates remains unperturbed.

Pilomatrixoma

Clinical and histopathological features of two cases of pilomatrixoma are reported. The tumour in each case was slow-growing, asymptomatic and at the same site. Histopathology showed classical eosinophilic ghost cell, surrounded by basophilic cells, along with areas of calcification and keratinization.

Electron microscopic characteristics of actinomycetic agents having aetiological association with human leprosy and epizootic ulcerative syndrome of fish

The transmission electron microscopic (TEM) studies of the human leprosy derived chemoautotrophic nocardio-form (CAN) bacteria and EUS derived CAN bacteria showed presence of double contoured cell-walls consisting of an electron transparent and a dense layer. The fibrillar structures on the surface of these CAN bacterial cells also suggested their similarity to the human tissue derived Mycobacterium leprae cells. These EM studies further revealed mycelial and coccoid bodies in all these bacteria as was observed originally.

Culture of nocardioform bacilli from leprosy patients & clinical evaluation of nocardioform bacilli derived antigen

An antigen derived from cultured nocardioform bacilli was compared with Mitsuda lepromin in intradermal skin test reactions. Nocardioform bacilli were cultured in gelatin minimal medium from the tissue fluid of 85 lepromatous patients (56 M, 29 F). Of these, 65 samples showed uncontaminated growth of the organism, which were pooled for the manufacture of the test antigen. This antigen was intradermally tested in 50 untreated leprosy patients irrespective of the type, together with Mitsuda lepromin and sterile gelatin minimal media, which served as a control. No early reaction was observed at 72 h, while the late reaction at 28 days was positive in all patients in the Tuberculoid (TT) group with both antigens. Eighteen patients (81.8%) in the Borderline tuberculoid (BT) group reacted strongly to Mitsuda lepromin at 28 days, while 21 patients (95.5%) in this group showed a strong late reaction with the test antigen. The lepromatous (LL) group did not show any reaction with the two antigens. It is inferred that nocardioform bacilli are easy to cultivate, and that the test antigen compares well with Mitsuda lepromin.

Concurrent skin and nerve histology in leprosy and its role in the classification of leprosy

Concurrent skin and nerve histology was evaluated in 60 leprosy patients (25 BT, 28 BL and 7 LL). The twin aims were to study the comparative histology and the usefulness of nerve histology in the classification of the disease. In BT patients, clinical and histological classification was in agreement in 11 (44%) skin and 17 (68%) nerve biopsies. Concurrent skin and nerve histology was in consonance in 14 (56%) BT patients, while in 6 (24%) patients, only nerve histology was helpful in the classification of the disease, the skin histology being non-specific. Nerve histology was classified as BL in 3 (12%) BT patients, the skin histology was non-specific. In the BL group, the histology of 23 (82.4%) nerve biopsies correlated with the clinical classification, in contrast to skin histology which correlated with clinical assessment in 19 (68%) patients only. In the LL patients, the histology of nerve correlated with the clinical classification in 5 patients (71.4%), compared to histology of the skin in 4 (57%) patients only. The GF was higher in the nerves than in the skin throughout the leprosy spectrum (BT, BL, LL); the difference was, however, marginal in BL leprosy. The average bacteriological index (BI) was higher in nerves (4+) compared to that of skin histology and slit skin smears (3+) in BL leprosy. There was, however, no difference in the BI of the slit skin smears, skin and nerve biopsies in lepromatous leprosy.(ABSTRACT TRUNCATED AT 250 WORDS)

Paucibacillary multidrug therapy in leprosy. 7 1/2 years experience

Three hundred and twenty-three paucibacillary (PB) leprosy patients were treated with WHO-recommended multidrug therapy (MDT) and followed up for over 7 1/2 years. The paucibacillary MDT regimen (PBR) was well accepted and tolerated. Complete clinical regression was attained in 61.2% patients after 6 doses of PBR. Persistence of clinical activity after 6 months of therapy was associated with occurrence of type I upgrading reaction, presence of six or more patches and more than two thickened major nerve trunks. Reversal reactions were encountered in 15.9% patients, one third of which were accompanied by severe neuritis. Delayed upgrading reaction occurred in six patients, two patients had relapse one and two years after stopping of PBR. The WHO recommended MDT regimen for paucibacillary cases needs careful evaluation and it may be necessary to extend the treatment beyond six months in certain situations.

Faun-tail nevus--a case report

A Case of faun-tail nevus is presented. A long tuft of hair over the back in the lumbar region hid a bony defect of the fifth lumbar spine. No neurological symptoms were encountered.

Involvement of the legs in idiopathic striae distensae--a case report

A case of idiopathic striae distensae (ISD) is presented. The patient was a healthy young adult with no history of weight lifting, use of systemic or local corticosteroids, infections or trauma. Horizontally disposed striae were located on the abdomen, back and legs. To the best of our knowledge this is the first report case of ISD where idiopathic striae were present below the knees.