Inhibiting ACK1-mediated phosphorylation of C-terminal Src kinase counteracts prostate cancer immune checkpoint blockade resistance

Solid tumours are highly refractory to immune checkpoint blockade (ICB) therapies due to the functional impairment of effector T cells and their inefficient trafficking to tumours. T-cell activation is negatively regulated by C-terminal Src kinase (CSK); however, the exact mechanism remains unknown. Here we show that the conserved oncogenic tyrosine kinase Activated CDC42 kinase 1 (ACK1) is able to phosphorylate CSK at Tyrosine 18 (pY18), which enhances CSK function, constraining T-cell activation. Mice deficient in the Tnk2 gene encoding Ack1, are characterized by diminished CSK Y18-phosphorylation and spontaneous activation of CD8+ and CD4+ T cells, resulting in inhibited growth of transplanted ICB-resistant tumours. Furthermore, ICB treatment of castration-resistant prostate cancer (CRPC) patients results in re-activation of ACK1/pY18-CSK signalling, confirming the involvement of this pathway in ICB insensitivity. An ACK1 small-molecule inhibitor, (R)-9b, recapitulates inhibition of ICB-resistant tumours, which provides evidence for ACK1 enzymatic activity playing a pivotal role in generating ICB resistance. Overall, our study identifies an important mechanism of ICB resistance and holds potential for expanding the scope of ICB therapy to tumours that are currently unresponsive.

Discovery and molecular basis of subtype-selective cyclophilin inhibitors

Although cyclophilins are attractive targets for probing biology and therapeutic intervention, no subtype-selective cyclophilin inhibitors have been described. We discovered novel cyclophilin inhibitors from the in vitro selection of a DNA-templated library of 256,000 drug-like macrocycles for cyclophilin D (CypD) affinity. Iterated macrocycle engineering guided by ten X-ray co-crystal structures yielded potent and selective inhibitors (half maximal inhibitory concentration (IC₅₀) = 10 nM) that bind the active site of CypD and also make novel interactions with non-conserved residues in the S2 pocket, an adjacent exo-site. The resulting macrocycles inhibit CypD activity with 21- to >10,000-fold selectivity over other cyclophilins and inhibit mitochondrial permeability transition pore opening in isolated mitochondria. We further exploited S2 pocket interactions to develop the first cyclophilin E (CypE)-selective inhibitor, which forms a reversible covalent bond with a CypE S2 pocket lysine, and exhibits 30- to >4,000-fold selectivity over other cyclophilins. These findings reveal a strategy to generate isoform-selective small-molecule cyclophilin modulators, advancing their suitability as targets for biological investigation and therapeutic development.

DNA-templated compound library screening and structure-guided hit optimization resulted in the identification of selective macrocyclic inhibitors of cyclophilin isoforms CypD and CypE.

Role of nutraceuticals in cognition during aging and related disorders

Cognitive abilities are compromised with advancing age posing a great risk for the development of dementia and other related brain disorders. Genetic susceptibility as well as environmental exposures determine the fate of cognitive aging and its transition to pathological states. Emerging epidemiological and observational studies have revealed the importance of lifestyle factors including dietary patterns and nutritional intake in the maintenance of cognitive health and reducing the risk of neurodegenerative disorders. In this context, nutraceutical interventions have gained considerable attention in preventing age-related cognitive deficits and counteracting pathological processes. Nutraceuticals include dietary plants and derivatives, food supplements and processed foods with nutritional and pharmaceutical values. The present review highlights the importance of nutraceuticals in attenuating cognitive aging and its progression to dementia, with specific emphasis on chemical constituents, neurocognitive properties and mechanism of action.

Quantitative metabolic biomarker analysis of mild cognitive impairment in eastern U.P. and Bihar population

Mild cognitive impairment (MCI) is a transition phase between healthy individuals and Alzheimer's disease (AD). Therefore, diagnosis of MCI at early stage will help to delay or prevent its progression to disease. In the present study, we aim to identify the metabolic biomarkers, which can help in the diagnosis of MCI. We have screened 2000 elderly individuals from north India, out of which 200 were identified as MCI. We continued our study on 10 MCI individuals who regularly participated in the follow-up. The age and gender matched 10 healthy individuals were taken as control. These control and MCI individuals were subjected to neuropsychological examination such as Hindi mental state examination (HMSE) and Montreal cognitive assessment (MOCA) followed by ¹H Nuclear Magnetic Resonance (NMR) analysis. Remarkable changes were noted between control and MCI individuals at metabolic level. In silico study showed the involvement of eight metabolites in MCI. We found higher level of lactate, N-acetyl aspartate, histidine and lower level of formate, choline, alanine, creatinine and glucose in blood plasma of MCI individuals compared to control. Further, In silico study showed that choline might be directly associated with MCI or AD. Such In silico study with quantitative metabolite analysis of plasma could be used as diagnostic biomarkers for the identification of MCI.

Correction to: Age-related expression of Neurexin1 and Neuroligin3 is correlated with presynaptic density in the cerebral cortex and hippocampus of male mice

The corresponding author noticed in his published paper that the images (30 weeks, CC, 10, 30 and 50 weeks DG) of fig. 3b are inadvertently duplicated with the images of fig. 3a. Now, these images have been replaced in the corrected panel (Fig. 3b) below.

What Makes a Kinase Promiscuous for Inhibitors?

ATP-competitive kinase inhibitors often bind several kinases due to the high conservation of the ATP binding pocket. Through clustering analysis of a large kinome profiling dataset, we found a cluster of eight promiscuous kinases that on average bind more than five times more kinase inhibitors than the other 398 kinases in the dataset. To understand the structural basis of promiscuous inhibitor binding, we determined the co-crystal structure of the receptor tyrosine kinase DDR1 with the type I inhibitors dasatinib and VX-680. Surprisingly, we find that DDR1 binds these type I inhibitors in an inactive conformation typically reserved for type II inhibitors. Our computational and biochemical studies show that DDR1 is unusually stable in this inactive conformation, giving a mechanistic explanation for inhibitor promiscuity. This phenotypic clustering analysis provides a strategy to obtain functional insights not available by sequence comparison alone.

Epigenetic Regulation of Memory-Therapeutic Potential for Disorders

BACKGROUND

Memory is a vital function which declines in different physiological and pathological conditions such as aging and neurodegenerative diseases. Research in the past has reported that memory formation and consolidation require the precise expression of synaptic plasticity genes. However, little is known about the regulation of these genes. Epigenetic modification is now a well established mechanism that regulates synaptic plasticity genes and neuronal functions including memory. Therefore, we have reviewed the epigenetic regulation of memory and its therapeutic potential for memory dysfunction during aging and neurological disorders.

METHOD

Research reports and online contents relevant to epigenetic regulation of memory during physiological and pathological conditions have been compiled and discussed.

RESULTS

Epigenetic modifications include mainly DNA methylation and hydroxymethylation, histone acetylation and methylation which involve chromatin modifying enzymes. These epigenetic marks change during memory formation and impairment due to dementia, aging and neurodegeneration. As the epigenetic modifications are reversible, they can be modulated by enzyme inhibitors leading to the recovery of memory.

CONCLUSION

Epigenetic modifications could be exploited as a potential therapeutic target to recover memory disorders during aging and pathological conditions.

Neutrophil lymphocyte ratio (NLR) as a predictive biomarker for PD-1/PD-L1 directed therapy in metastatic non-small cell lung cancer (NSCLC)

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Background: PD-1/PD-L1 directed therapy is approved in the second and first-line treatment of metastatic NSCLC. While PD-L1 expression can be predictive of outcomes with such therapy, there remains a need for additional biomarkers to guide patient (pt) selection. NLR is an easy to use biomarker that was predictive for clinical outcomes in the treatment of kidney cancer and melanoma. This study evaluated NLR as a predictor of response rate (RR), PFS and OS in metastatic NSCLC pts treated with PD-1/PD-L1 inhibitors as second line therapy. Methods: A retrospective chart review of NSCLC pts treated with PD-1/PD-L1 inhibitors was conducted. Data were collected on pt demographics, smoking status [<10 pack years (PY) and ≥10 PY], histology, NLR pre-therapy and NLR post 3 doses. Correlation with RR, PFS and OS was evaluated by univariate and multivariate analyses. Results: 58 pts with NSCLC were included in the analyses. Median age was 62.5 yrs (39-85) and 34(59%) were male. 36 (62%) were Caucasian, 16(28%) African American and 6(10%) Asian. 39 (63%) had adenocarcinoma histology, 23 (40%) patients smoked <10 PY and 35(60%) ≥10 PY. On Day 1, 33 (57 %) had NLR <4 and 28 (48%) had NLR <4 after cycle 3. 43 (74%) pts had disease control with 2 (3%) complete remissions, 22 (38%) partial responses. Pre-therapy NLR ≥4 was associated with shorter PFS (HR = 1.79 p=0.10) and shorter OS (HR =2.57; p=0.04). NLR≥4 post 3doses was associated with shorter PFS (HR= 2.14,p=0.04) and shorter OS (HR= 3.11; p=0.04). In multivariate analysis, heavy smoking (≥10 PPY) was associated with longer PFS; HR=0.50 (95% CI 0.25-1.01; p=0.05); but had no effect on OS with a HR 0.58(95%CI 0.21-1.56; p=0.28). Squamous histology appeared to have longer PFS HR=0.62 (95% CI 0.61-2.35: p =0.61), though not statistically significant. Conclusions: Pretherapy NLR ≥4 was found to be associated with shorter OS in NSCLC pts treated with PD-1/PD-L1 therapy. This suggests that NLR may be a predictive factor for benefit with PD1/PDL1 therapy. A larger sample study is warranted to validate this observation. [Table: see text]

Histone Deacetylase 2 Inhibition Attenuates Downregulation of Hippocampal Plasticity Gene Expression during Aging

The brain undergoes several anatomical, biochemical, and molecular changes during aging, which subsequently result in downregulation of synaptic plasticity genes and decline of memory. However, the regulation of these genes during aging is not clearly understood. Previously, we reported that the expression of histone deacetylase (HDAC)2 was upregulated in the hippocampus of old mice and negatively correlated with the decline in recognition memory. As HDAC2 regulates key synaptic plasticity neuronal immediate early genes (IEGs), we have examined their expression and epigenetic regulation. We noted that the expression of neuronal IEGs decreased both at mRNA and protein level in the hippocampus of old mice. To explore the underlying regulation, we analyzed the binding of HDAC2 and level of histone acetylation at the promoter of neuronal IEGs. While the binding of HDAC2 was higher, H3K9 and H3K14 acetylation level was lower at the promoter of these genes in old as compared to young and adult mice. Further, we inhibited HDAC2 non-specifically by sodium butyrate and specifically by antisense oligonucleotide to recover epigenetic modification, expression of neuronal IEGs, and memory in old mice. Inhibition of HDAC2 increased histone H3K9 and H3K14 acetylation level at the promoter of neuronal IEGs, their expression, and recognition memory in old mice as compared to control. Thus, inhibition of HDAC2 can be used as a therapeutic target to recover decline in memory due to aging and associated neurological disorders.

Spotlight on necitumumab in the treatment of non-small-cell lung carcinoma

The treatment options for metastatic non-small-cell lung cancer (NSCLC) have expanded dramatically in the last 10 years with the discovery of newer drugs and targeted therapy. Epidermal growth factor receptor (EGFR), when aberrantly activated, promotes cell growth and contributes in various ways to the malignant process. EGFR has become an important therapeutic target in a variety of malignancies. Small-molecule tyrosine kinase inhibitors (TKIs) of EGFR are being used to treat advanced NSCLC and are particularly effective in the presence of EGFR mutations. Monoclonal antibodies have also been developed that block the EGFR at the cell surface and work in conjunction with chemotherapy. Necitumumab is a second-generation fully human IgG1 monoclonal antibody that has shown promise in metastatic NSCLC. The benefit has mostly been restricted to squamous cell lung cancer in the frontline setting. Considering that the survival advantage for these patients was modest, there is a need to discover biomarkers that will predict which patients will likely have the best outcomes. This review focuses on the development and clinical trial experience with necitumumab in NSCLC.

Anxiety like behavior due to perinatal exposure to Bisphenol-A is associated with decrease in excitatory to inhibitory synaptic density of male mouse brain

Bisphenol-A (BPA) is a synthetic endocrine disruptor which causes anxiety like behavior in rodents, though the underlying mechanism is not clearly understood. As excitatory-inhibitory synaptic proteins are the key regulators of anxiety, we have examined the effect of perinatal exposure to BPA on this behavior and the expression of excitatory (PSD95), inhibitory (gephyrin) and presynaptic density marker (synaptophysin) proteins in cerebral cortex and hippocampus of 3 and 8 weeks postnatal male mice. In open field (OF) test, BPA exposure reduced the time spent, number of entries and distance travelled in the central zone as compared to control in 8 weeks mice. On the other hand, elevated plus maze (EPM) results showed decrease in time spent and number of entries to the open arms. Immunoblotting and immunofluorescence analysis showed significant downregulation of PSD95 and synaptophysin, but upregulation of gephyrin, leading to reduction in excitatory to inhibitory protein ratio and synaptic density in postnatal 3 and 8 weeks mice. Thus, our findings show that the anxiety like behavior due to perinatal exposure to BPA is associated with decrease in excitatory to inhibitory synaptic density in postnatal male mice.

Predictive and Prognostic Biomarkers in Non-Small Cell Lung Cancer

Therapy of non-small cell lung cancer (NSCLC) patients has evolved over the past few years with the incorporation of targeted therapy and immune therapy. These changes have increased the importance of prognostic and predictive biomarkers to enable practicing physicians in making the most appropriate treatment decisions for NSCLC patients. A variety of prognostic factors based on clinical and pathologic features determine the overall outcome of the patient and these factors do influence decisions regarding initiation of therapy. The most important prognostic factors remain stage of the disease at diagnosis and performance status. For years, the only approved systemic therapy for NSCLC patients was chemotherapy. Despite attempts at defining factors that influence efficacy of chemotherapeutic agents, pemetrexed is the only chemotherapy drug that has differential activity based on a specific factor. In recent years, there is increasing focus on defining the molecular alterations critical to the oncogenic phenotype of NSCLC and targeting these alterations for therapeutic benefit. In addition, there is increasing use of immune-modulating drugs, specifically anti-PD-1 drugs, in advanced NSCLC patients. Several studies have shown that the probability of clinical benefit from these agents is greater in patients with NSCLCs that express PD-L1. The totality of these data suggests that determination of predictive markers prior to initiation of therapy is critical.

Presenilin 2 overexpression is associated with apoptosis in Neuro2a cells

Presenilin 1 (PS1) and PS2 are evolutionarily conserved transmembrane proteins of the aspartyl protease family. Initially, they were reported to be associated with the early onset of familial, early-onset Alzheimer’s disease. PS1 has been implicated in several crucial brain functions including developmental processes, synaptic plasticity, and processing of various molecules, while PS2 has been poorly studied and is considered to be a compensatory partner of PS1. Certain controversial reports have suggested that PS2 has a role in apoptosis, though the underlying mechanism is not clear. To ascertain the role of PS2 in apoptosis, mouse neuroblastoma cells (Neuro2a) were transfected with a cDNA construct encoding full length mouse PS2 and analyzed for viability, expression of PS1, PS2, Bax and p53, Bax protein, and status of chromatin condensation. Our results showed reduced viability, condensed chromatin and higher expression of Bax at mRNA and protein levels, but no change in the expression of p53 and PS1 in PS2-overexpressing Neuro2a cells. Thus, it is evident that PS2, independent of PS1, is associated with apoptosis via a Bax-mediated pathway. These findings might help in the understanding of the involvement of PS2 in apoptosis and its associated brain disorders.

Multifaceted and personalized therapy of advanced prostate cancer

PURPOSE OF REVIEW

A number of molecular and genomic biomarkers that possess the ability to guide treatment or 'actionable targets' are being reported in metastatic prostate cancer. In addition, pathways of resistance to existing therapies and novel agents to overcome them are currently under active investigation. The next wave of investigations is focused on personalized therapy of prostate cancer. The focus of this review article is to provide an update on clinical development in advanced prostate cancer and to highlight the ongoing investigations of biomarker discovery, and ways of overcoming therapeutic resistance. The next generation of clinical trials developing novel targets and compounds promises to be in populations enriched with specific marker expression.

RECENT FINDINGS

The breakthrough report, of the ability of the androgen receptor variant 7 mutation, detected in circulating tumor cells, to predict the lack of response to abiraterone or enzalutamide, and the remarkable responses of poly adenosine diphosphate ribose polymerase inhibitors in prostate cancer with DNA repair mutations have elevated hopes of a bright future in the biomarker-driven therapeutic arena. Novel targets such as bromodomain extra terminal-1 and phosphatidylinositol 3-kinase hold promise for the possibility of overcoming resistance. Novel hormone agents are also under active study.

SUMMARY

As the clinical application of the multifaceted therapies narrows down to enriched patient populations selected by genomic testing, the therapeutic efficiency will escalate considerably. Novel targets, resistance mechanisms and relevant agents are being avidly tested, and the dream of personalized medicine is emerging into reality.

Age-dependent decline of nogo-a protein in the mouse cerebrum

Nogo-A, a myelin-associated neurite growth inhibitory protein, is implicated in synaptic plasticity. It binds to its receptor namely the Nogo-66 receptor1 (NgR1) and regulates filamentous (F) actin dynamics via small GTPases of the Rho family, RhoA kinase (ROCK), LimK and cofilin. These proteins are associated with the structural plasticity, one of the components of synaptic plasticity, which is known to decline with normal aging. So, the level of Nogo-A and its receptor NgR1 are likely to vary during normal brain aging. However, it is not clearly understood how the levels of Nogo-A and its receptor NgR1 change in the cerebrum during aging. Several studies show an age- and gender-dependent decline in synaptic plasticity. Therefore, the present study was planned to analyze the relative changes in the mRNA and protein levels of Nogo-A and NgR1 in both male and female mice cerebrum during normal aging. Western blot analysis has shown decrease in Nogo-A protein level during aging in both male and female mice cerebrum. This was further confirmed by immunofluorescence analysis. RT-PCR analysis of Nogo-A mRNA showed no significant difference in the above-mentioned groups. This was also supported by in situ hybridization. NgR1 protein and its mRNA expression levels showed no significant alteration with aging in the cerebrum of both male and female mice. Taken together, we speculate that the downregulation of Nogo-A protein might have a role in the altered synaptic plasticity during aging.

Role of CREB signaling in aging brain

During aging, brain undergoes several changes which influence its function through alteration in the expression of genes. Some of these genes are regulated by estrogen which requires a host of coregulator proteins including CREB. In brain, CREB is expressed in different regions and regulates a wide range of functions such as cellular growth, proliferation and memory in response to a variety of intracellular signaling events including synaptic efficacy and long-lasting changes in synaptic plasticity. In response to signals at the cell surface, CREB is phosphorylated in the nucleus by various protein kinases via secondary messengers such as cAMP and/or Ca+2 for regulating specific genes. Alterations in CREB signaling lead to cognitive deficits as observed in normal aging and neurodegenerative diseases. In brain, the expression of CREB changes with age, but its variation with sex is not known. So, in this review paper, we summarize recent findings indicating age and sex dependent expression of CREB and its interaction with estrogen receptor (ER)β, and the role of CREB signaling in brain aging and diseases. Such understanding of CREB signaling through ER may help to design therapeutic strategies for age related cognitive deficits and neurodegenerative disorders.

The structure of XIAP BIR2: understanding the selectivity of the BIR domains

The high-resolution crystal structures of apo and peptide-bound XIAP BIR2 are presented and compared with BIR3 structures to understand their selectivity. This crystal system can be used to determine the structures of BIR2–inhibitor complexes.

XIAP, a member of the inhibitor of apoptosis family of proteins, is a critical regulator of apoptosis. Inhibition of the BIR domain–caspase interaction is a promising approach towards treating cancer. Previous work has been directed towards inhibiting the BIR3–caspase-9 interaction, which blocks the intrinsic apoptotic pathway; selectively inhibiting the BIR2–caspase-3 interaction would also block the extrinsic pathway. The BIR2 domain of XIAP has successfully been crystallized; peptides and small-molecule inhibitors can be soaked into these crystals, which diffract to high resolution. Here, the BIR2 apo crystal structure and the structures of five BIR2–tetrapeptide complexes are described. The structural flexibility observed on comparing these structures, along with a comparison with XIAP BIR3, affords an understanding of the structural elements that drive selectivity between BIR2 and BIR3 and which can be used to design BIR2-selective inhibitors.

Overexpression of mouse estrogen receptor-β decreases but its transactivation and ligand binding domains increase the growth characteristics of E. coli

Escherichia coli is one of the most common and widely used prokaryotic hosts for the expression of recombinant proteins. The overexpression of recombinant proteins occasionally increases bacterial growth but sometimes reduces it and becomes lethal to the host cells. Here, we report the overexpression of mouse ER-β and its domains in the prokaryotic expression system and its opposite effect on the growth characteristics of E. coli. ER-β protein was immunologically detected as a 53 kDa his-tag protein in the pellet of the bacterial lysate. Its overexpression, as reflected by the total protein content and expression pattern, resulted in the decrease of bacterial growth. However, the overexpression of ER-β transactivation domain (TAD) using pIVEX and ligand binding domain (LBD) using pRSETA in E. coli BL21 (DE3) show opposite pattern. TAD was immunologically detected as 20 kDa and LBD as 22 kDa protein in the supernatant of the bacterial lysate and their overexpression increased the bacterial growth.

Gonadal steroids do not affect apolipoprotein E expression in aging mouse cerebral cortex

The allelic variant of apolipoprotein (Apo) E4 is a known risk factor for the development of most common late onset form of Alzheimer's disease (AD). As aging is associated with reduced circulating level of gonadal steroid hormones, hormone replacement therapies have been used for the possible treatment of AD. Both estrogen and testosterone have beneficial effects on brain due to interaction with apoE, but the underlying mechanism is still not clear. In this article, we report the effects of gonadectomy and hormone supplementation on apoE protein level in male and female mouse cerebral cortex during normal aging. We could not get any effect of gonadectomy and estradiol or testosterone treatment in adult and old mice of either sex. This suggests that during normal aging apoE protein level is not affected due to steroid hormone withdrawal or supplementation in the mouse cerebral cortex.

Interaction of Estrogen Receptor Associated Protein (ERAP) 140 with ER beta decreases but its expression increases in aging mouse cerebral cortex

Following binding to cognate ligand, estrogen receptor (ER) beta interacts with specific responsive elements of the target genes and recruits a host of nuclear proteins for hormone dependent gene regulation. However, it is poorly known which proteins interact with ER beta in mouse brain and whether their interaction and expression change with age. In this report, we have used his-tag mouse ER beta for interaction with nuclear proteins of cerebral cortex of young (6 +/- 1 weeks), adult (25 +/- 2 weeks), and old (70 +/- 5 weeks) female mice. We have identified estrogen receptor-associated protein (ERAP) 140 as one of the interacting proteins and studied its interaction by pull down immunoblotting, far-Western blotting and immunoprecipitation, and expression by western blotting. The data show that ERAP 140 interacts with ER beta and its interaction decreases but its expression increases with age in mouse cerebral cortex, suggesting its role in estrogen-mediated brain functions during aging.

Interaction of estrogen receptor-alpha ligand binding domain with nuclear proteins of aging mouse brain

After the interaction of estrogen with the ligand binding domain (LBD) of mouse estrogen receptor-alpha (mERalpha) and hormone-responsive elements of target genes, many nuclear proteins are recruited to regulate the expression of specific genes. Because it is not known which brain proteins interact with LBD or whether these proteins vary with age and sex, we used pull-down assay and far Western blotting to detect five nuclear proteins of 160, 140, 87, 60, and 46 kD in the mouse brain. These interacting proteins were identified as PELP1, RIP140, PGC1alpha, BAF60, and ADA3, respectively. The level of PELP1, RIP140, PGC1alpha, and BAF60 decreased drastically in old compared with adult male mice, whereas the ADA3 level showed no significant change. PELP1, PGC1alpha, and BAF60 levels were lower in old male compared with female mice. Thus we report the identification and interaction of five nuclear proteins with mERalpha-LBD, indicating their role in estrogen signaling and brain functions during aging.

Interaction of estrogen receptor-alpha transactivation domain with nuclear proteins of mouse brain: p68 RNA helicase shows age- and sex-specific change

Estrogen receptor (ER)-alpha interacts with nuclear proteins to mediate its multiple functions in the brain. However, it is not known which proteins interact with the ERalpha-transactivation domain (TAD) in mouse brain and whether they change with age and sex. Therefore, we have used affinity-purified GST-tagged mouse ERalpha-TAD fusion protein for interaction with nuclear proteins from the mouse brain. The pull-down assay and far-Western blotting detected four nuclear proteins of 100, 80, 68, and 50 kD. We have recently identified the 80-kD protein as MTA1 and demonstrated its decrease in old age. Here we report alteration in the interaction and expression of the 68-kD protein of adult and old mice of both sexes. This protein was identified as p68 RNA helicase through NCBI database search, immunoprecipitation, and immunoblotting. Further analysis showed that the extent of its interaction was relatively lower in old mice of both sexes and in male mice of both ages compared with their counterparts. However, the expression of p68 was significantly lower in old males compared with adult males, although other groups did not show significant changes. Such age- and sex-specific interaction of p68 suggests its implication in ERalpha-mediated brain functions during aging.

GST-tagged mouse estrogen receptor alpha-transactivation domain fusion protein is specifically degraded during its over-expression in E. coli and purification

Escherichia coli BL21 (DE3) is commonly used for the overproduction of fusion proteins. Using this system, we recently reported the overproduction of histidine-tagged mouse estrogen receptor (ER) alpha-ligand binding domain as an intact 30 kD protein and its inhibitory effect on the growth of bacteria. However, when GST-tagged mouse ERalpha transactivation domain (TAD) was overproduced using this system, it showed no effect on the growth of bacteria but was specifically degraded during its expression and purification. Here we report the expression of 47 kD GST-tagged mouse ERalpha-TAD protein, which was degraded partially and specifically into 46 and 43 kD fragments. This fusion protein was further degraded into 37, 31, 29 and 26 kD fragments during its purification by affinity chromatography. Such specific degradation of GST-tagged mouse ERalpha-TAD during its overproduction in E. coli and purification indicates the induction of specific protease and suggests the modification of expression system.

Role of steroid hormone coregulators in health and disease

The involvement of coactivators and corepressors, collectively termed as coregulators, increases the complexity of regulation of steroid hormone action. Following the interaction of the steroid hormone-receptor complex with the specific nucleotide sequences of target genes, the coregulators are recruited for activation or suppression of specific genes. The coregulators regulate a number of hormonal events during pregnancy, sex differentiation, development, reproduction and sexual behavior. They also exert equally important functions in non-reproductive tissues like heart, kidney, pancreas, bone and brain. The mutation and/or aberrant expression of these coregulators affect the normal function of steroid hormones and result in physiological abnormalities leading to the development of diseases. Therefore, understanding the role of coregulators in steroid hormone action is important and would help in developing the therapeutic strategy for the treatment of steroid-related diseases. In this review article, we describe the coregulators and their implication in health and pathogenesis of diseases. Furthermore, the possible therapeutic approach has been discussed for the treatment of steroid-related diseases, which will be of future interest in the field of medical sciences.

Anti-HBc screening in Indian blood donors: Still an unresolved issue

AIM: To study the seroprevalence of antibody to hepatitis B core antigen (anti-HBc) in healthy blood donors negative for HBsAg and to evaluate whether anti-HBc detection could be adopted in India as a screening assay for HBV in addition to HBsAg.

METHODS: A total of 1700 serum samples collected from HBsAg-negative healthy blood donors were tested for the presence of anti-HBc antibody (IgM + IgG). All samples reactive for anti-HBc antibody were then investigated for presence of anti-HBs and for liver function tests (LFTs). One hundred serum samples reactive for anti-HBc were tested for HBV DNA by PCR method.

RESULTS: Out of 1700 samples tested, 142 (8.4%) blood samples were found to be reactive for anti-HBc. It was significantly lower in voluntary (6.9%) as compared to replacement donors (10.4%, P = 0.011). Seventy-two (50.7%) anti-HBc reactive samples were also reactive for anti-HBs with levels > 10 mIU/mL and 70 (49.3%) samples were non-reactive for anti-HBs, these units were labeled as anti-HBc-only. These 142 anti-HBc reactive units were also tested for liver function test. HBV DNA was detected in only 1 of 100 samples tested.

CONCLUSION: Keeping in view that 8%-18% of donor population in India is anti-HBc reactive, inclusion of anti-HBc testing will lead to high discard rate. Anti-HBs as proposed previously does not seem to predict clearance of the virus. Cost effectiveness of introducing universal anti-HBc screening and discarding large number of blood units versus considering ID NAT (Individual donor nuclic acid testing) needs to be assessed.

Binding of estrogen receptor alpha promoter to nuclear proteins of mouse cerebral cortex: effect of age, sex, and gonadal steroids

Majority of estrogen actions in the brain are mediated by estrogen receptor (ER) alpha which in turn is regulated by several factors like circulating levels of gonadal steroid hormones 17beta-estradiol and testosterone, sex and age of the organism. The expression of ERalpha is regulated through interaction between cis-elements of its promoter and proteins present in the nuclei. Here, we have used electrophoretic mobility shift assay (EMSA) to analyze the effect of age, sex, 17beta-estradiol, and testosterone on the binding of ERalpha promoter (-91 to +46 bp) to nuclear proteins from the mouse cerebral cortex. EMSA revealed the formation of three specific complexes in all groups. However, the intensity of these complexes varied as a function of age, sex and treatment with 17beta-estradiol and testosterone. Nuclear proteins from the cerebral cortex of both sexes showed reduced binding with promoter fragment in old mice. Further, competition analysis indicated stronger binding in females than males of both ages. The extent of binding was reduced by 17beta-estradiol and testosterone treatment in both ages and sexes. Thus, these findings demonstrate differential binding of nuclear proteins to mouse ERalpha promoter which may account for different functions of estrogen in the brain.

PS2 protein expression is upregulated by sex steroids in the cerebral cortex of aging mice

Mutations in presenilin (PS) genes cause majority of early onset Alzheimer's disease (AD), an age related neurodegenerative disorder. PS proteins undergo proteolytic cleavage to produce biologically active fragments, which constitute the catalytic core of the gamma-secretase enzyme. This enzyme cleaves beta-amyloid precursor protein (betaAPP) to generate Abeta peptides, which are influenced by sex steroids. Recently we have reported the downregulation of PS1 expression by sex steroids in the brain of adult mice. Here we have examined the effect of gonadectomy and subsequent administration of gonadal hormones 17beta-estradiol and testosterone on the level of PS2 C-terminal fragment (CTF) in the cerebral cortex of adult and old AKR strain mice of both sexes. PS2 expression was downregulated following gonadectomy, but upregulated by supplementation of gonadal steroids in both age groups and sexes. Thus these results demonstrate up-regulation of PS2 protein expression by sex steroids, which in turn may influence PS2 associated brain functions.

Transcription of estrogen receptor alpha and beta in mouse cerebral cortex: effect of age, sex, 17beta-estradiol and testosterone

Estrogen actions are mainly mediated by estrogen receptor (ER)alpha and ERbeta which in turn are regulated by several factors including age, sex and gonadal steroid hormones 17beta-estradiol and testosterone. In the present study, we have used nuclear run-off assay to examine the effect of these factors on the rate of transcription of ERalpha and ERbeta of mouse cerebral cortex. The run-off assay result was further corroborated with the measurement of steady state level of ERalpha and ERbeta mRNA by semiquantitative RT-PCR method. Our results reveal that ERalpha transcription rate decreases in old mice of both sexes, whereas ERbeta transcription rate decreases only in old females when compared to their adult counterparts. 17beta-Estradiol supplementation reduces the transcription rate of ERalpha and ERbeta in all groups except in adult male while testosterone treatment down regulates the transcription rate of ERalpha and ERbeta in all groups. The semiquantitative RT-PCR analysis reveals that the level of ERalpha mRNA decreases in old male but shows no effect in old female as compared to adult counterpart. In contrast, ERbeta transcript level decreases in old mice of both sexes. Furthermore, ERalpha mRNA level is higher in adult female than in adult male but no sex-dependent difference is seen in ERbeta mRNA level. Supplementation of 17beta-estradiol shows no significant alteration but testosterone reduces the ERalpha level in male mice, while 17beta-estradiol and testosterone down regulate the ERalpha level in female mice of both ages. In case of ERbeta, 17beta-estradiol decreases the transcript level in all groups except adult male while testosterone treatment results in the down regulation of transcript level in all groups. Thus these findings suggest differential effects of age, sex, 17beta-estradiol and testosterone supplementation on the transcription of mouse ER genes which may account for differences in the protein levels of ERalpha and ERbeta and their functions in the brain.

Aging of Brain: Role of Estrogen

The brain undergoes many structural and functional changes during aging. Some of these changes are regulated by estrogens which act mainly through their intracellular receptors, estrogen receptor ERalpha and ERbeta. The expression of these receptors is regulated by several factors including their own ligand estrogen, and others such as growth hormone and thyroid hormone. The levels of these factors decrease during aging which in turn influence estrogen signaling leading to alterations in brain functions. In the present paper, we review the effects of aging on brain structure and function, and estrogen action and signaling during brain aging. The findings suggest key role of estrogen in the maintenance of brain functions during aging.

Expression of estrogen receptor (ER) α and β in mouse cerebral cortex: Effect of age, sex and gonadal steroids

Estrogen receptor (ER), which mediates the multiple effects of estrogen in brain, is regulated by several factors including its own ligand. In the present study, we have examined the effect of age, sex and gonadal steroids (estrogen and testosterone) on the level of ERalpha and ERbeta in the cerebral cortex of AKR mice. Adult and old mice of both sexes were divided into four groups: intact, gonadectomized, 17beta-estradiol treated and testosterone treated. Western blot analysis showed higher level of ERalpha and ERbeta in the cerebral cortex of adult female than male mice. ERbeta level decreased significantly with advancing age in both sexes, whereas 17beta-estradiol supplementation decreased ERalpha level in old male and increased in old female, it also increased ERbeta level in old male and adult female. On the other hand, testosterone treatment decreased ERalpha level significantly in old female and ERbeta level in adult female but increased ERbeta level in male mice of both ages. Thus, these findings showed that the expression of ERalpha and ERbeta protein is differentially influenced by age, sex and gonadal steroids in the mouse cerebral cortex, suggesting differences in ER-mediated brain functions.

In the cerebral cortex of female and male mice, amyloid precursor protein (APP) promoter methylation is higher in females and differentially regulated by sex steroids

The over-expression of amyloid precursor protein (APP) gene in certain areas of the brain indicates abnormalities in gene regulation as an important factor for the development of Alzheimer's disease (AD). We have reported recently that APP mRNA expression is lower in female as compared to male and is regulated by sex steroids. As methylation of promoter is crucial for such regulation, we have used isoschizomeric restriction enzymes MspI and HpaII to analyze the pattern of APP promoter methylation in the cerebral cortex of intact, gonadectomized, testosterone- and estradiol-treated adult and old mice of both sexes. Southern blots of DNA digested with HindIII/MspI or HindIII/HpaII from different groups of mice were probed with a 1.27-kb DIG-11-dUTP labeled APP promoter fragment. The results revealed four distinct bands of 315 bp, 596 bp, 911 bp, and 2.6 kb by MspI, a single band of 2.6 kb by HpaII in all groups and an additional 2.9 kb in intact and estradiol treated old male and testosterone-treated adult female mice. The intensity of 2.6-kb band was relatively lower in intact female as compared to male and varied with different treatments in both ages, indicating the modulation of methylation. Thus, these findings showed that APP promoter methylation is higher in female and differentially regulated by sex steroids in the mice cerebral cortex, suggesting a strong correlation between promoter methylation and transcriptional silencing of APP.

Estradiol regulates APP mRNA alternative splicing in the mice brain cortex

Alternative splicing of amyloid precursor protein (APP), one of the candidate genes for Alzheimer's disease, yields three major mRNAs, which give rise to APP770, APP751 and APP695 protein isoforms. Out of these three isoforms, APP695 is expressed most predominantly in the brain. The splicing and processing of APP are shown to be influenced by several factors including hormones. In this study, we report the effect of withdrawal and administration of sex steroid hormones on the alternative splicing of APP mRNA during aging in the brain cortex of mice of both sexes. The level of APP695 mRNA isoform was higher in intact adult as compared to old mice of both sexes. Gonadectomy upregulated the APP695 mRNA isoform levels in all groups except in adult female where the level was downregulated. Estradiol supplementation upregulated the level of APP695 mRNA isoform in all groups except in old male where the level was downregulated. Thus these results show that the level of APP695 mRNA changes with age and estradiol may play a key role in the development of Alzheimer's disease by modulating the level of APP mRNA isoforms.

Sex steroids reduce DNaseI accessibility of androgen receptor promoter in adult male mice brain

We have previously reported that androgen receptor (AR) expression is inversely correlated to its promoter methylation and is regulated by sex steroids. As chromatin structure plays an important role in transcriptional regulation, the effect of sex steroids on DNaseI accessibility of chromatin of AR promoter was examined in the brain cortex of adult and old mice of both sexes. Nuclei were digested with different concentrations of DNaseI and the extracted DNA was further cleaved by PstI and analyzed by Southern hybridization with DIG-labeled 695-bp AR promoter. With 50 U DNaseI, the intensity of PstI-specific 1.45-kb band was lower in intact female as compared to male groups, suggesting increased nuclease accessibility in female than male. Although gonadectomy increased DNaseI accessibility remarkably in male and female of both ages, testosterone decreased the accessibility in adult but increased in old male. Estradiol, on the other hand, decreased DNaseI accessibility in both adult male and old female but increased in old male and adult female. Thus, these findings suggest that the chromatin conformation of AR promoter varies with age and sex and its accessibility to DNaseI is reduced by testosterone and estradiol in the brain cortex of adult male mice.

Androgen receptor mRNA is inversely regulated by testosterone and estradiol in adult mouse brain

Androgen receptor (AR) is expressed in different tissues including the brain and is under regulation by sex steroid hormones. It mediates the action of androgen which plays a key role in learning, memory, and other brain functions that deteriorate with increasing age. We have correlated the expression of AR mRNA with its promoter methylation and their regulation by testosterone and estradiol in the brain cortex of adult and old male and female mice. Results revealed that (i) AR mRNA expression was significantly higher in male than in female mice. (ii) In both sexes, AR mRNA level was down-regulated by testosterone in adult and old, but up-regulated by estradiol only in adult mice. (iii) Methylation of AR core promoter was increased by testosterone, but decreased by estradiol. These findings show that AR mRNA expression and its core promoter methylation are inversely regulated by testosterone and estradiol in the adult mice brain cortex. Such regulation of AR expression might influence androgen action during aging of the mice brain.

Estrogen receptor ? expression in mice kidney shows sex differences during aging

We have used semi quantitative RT-PCR and western blotting for the analysis of expression of estrogen receptor (ER) alpha and beta mRNA and protein in the kidney of adult and old mice of both sexes. Uterus, a well-known target for estrogen action, was used for comparison. As compared to adult, the expression of both ER alpha mRNA and protein of old mice decreased in male but increased in female. However, unlike uterus, neither ERbeta mRNA nor protein could be detected in the kidney of adult or old mice. Thus the present data reveal that the expression of ERalpha in mice kidney shows sex differences during aging.

Amplification of exons 4 and 5 of androgen receptor gene by testosterone in aged female mouse brain cortex

We have investigated the effect of testosterone on the amplification of androgen receptor (AR) gene in the brain cortex of aging female mice. For this purpose, high molecular weight (HMW) DNA purified from the brain cortex of intact, gonadectomized, testosterone- and estradiol-treated adult and old female mice was digested with different restriction enzymes and used for Southern hybridization with 32P-labeled AR cDNA fragments representing different domains of AR. The results reveal that only exons 4 and 5 corresponding to amino-terminal part of the hormone binding domain of AR are amplified in testosterone-treated old female but not in adult mice. Densitometric analysis further shows that testosterone increases the copy number of exons 4 and 5 of mouse AR gene by four-fold. Reprobing of slot blots with estrogen receptor and cathepsin D cDNA as probes supports the observation that amplification occurs only in AR gene. The tissue specificity is also confirmed when the slot blot hybridization of mouse liver HMW DNA with AR cDNA fails to show similar amplification. As the restriction map analysis of Southern blots does not show restriction fragment length polymorphism, the possibility of structural rearrangement leading to amplification of AR gene is ruled out. Thus our results suggest that the in vivo induction of mouse AR gene amplification by testosterone is tissue- and age-specific, and might contribute to the progress of genetic instability in the brain of aged female mice.

Pyridoxal 5'-phosphate inhibits DNA binding of HNF1

An efficient Escherichia coli expression system was constructed for the production of a variant form of HNF1 protein having the additional five amino acid residues (Asp-Arg-Trp-Gly-Ser) at the NH(2)-terminal. The cDNA encoding HNF1 was ligated to 6 x His tag and inserted into an inducible bacterial expression vector pRSET A. After expression in E. coli, the recombinant product was purified by Ni-NTA affinity column chromatography. The purified product showed expected NH(2)-terminal sequence and specific binding to the HNF1 site. The effect of pyridoxal 5'-phosphate and its analogues on the binding activity of recombinant HNF1 was examined and found that only pyridoxal 5'-phosphate effectively inhibited the DNA binding. The concentration of pyridoxal 5'-phosphate that inhibited 50% of DNA binding was around 100 microM. Furthermore, we identified Lys197 of HNF1 molecule as the essential residue of DNA binding. These observations suggest that pyridoxal 5'-phosphate directly interacts with tissue-specific transcription factor HNF1 and modulates the binding to DNA.

Age- and sex-related expression of norbin in the brain cortex of mice

Norbin is a novel neuron specific protein that extends the neurites of neuronal cells. It is expressed in neural tissues like brain cortex, hippocampus, spinal cord and cerebellum. In this paper, we have studied the expression of norbin mRNA and protein in the brain cortex of male and female mice of different ages. Northern blot analysis showed that the level of norbin mRNA increased in both sexes during aging. However, Western blotting revealed that the protein increased in male but decreased in female with advancing age. These findings suggest that norbin is involved in brain function which is dependent on age and sex.

Purification, characterization and differentiation-dependent expression of a perchloric acid soluble protein from rat kidney

We have recently reported the presence of a novel perchloric acid soluble protein in rat liver (PSP1) that inhibits cell-free protein synthesis in a rabbit reticulocyte system. While studying the perchloric acid soluble proteins from different tissues of rats, we found that the kidney protein cross-reacted with antibody against the PSP1. In this investigation, we have purified a perchloric acid soluble protein from the rat kidney and studied its characterization and expression. The protein extracted from the postmitochondrial supernatant fraction with 5% perchloric acid was purified by ammonium sulfate fractionation and CM-Sephadex chromatography. By immunoscreening with the rabbit antisera against the PSP1, we detected a cDNA that contained an open reading frame of 411 bp, encoding a 137 amino-acid protein with a molecular mass of 14,149 daltons. The deduced amino acid sequence was completely identical with that of PSP1 from rat liver. The perchloric acid soluble protein from rat kidney (K-PSP1) also inhibited cell-free protein synthesis in the rabbit reticulocyte lysate system in a different manner than RNase A. Immunohistochemistry showed that the expression of K-PSP1 increased from fetal 17th day to postnatal 4th week, and it remained almost the same until the 7th week of postnatal age. Furthermore, the expression of K-PSP1 in the kidney of the nephrotic rat model was shown to be differentiation dependent. On the other hand, the expression of K-PSP1 in renal tumor cells was downregulated as compared with intact tissue. These results suggest that the expression of K-PSP1 is regulated in a differentiation-dependent manner in the kidney.

Synthesis and phosphorylation of androgen receptor of the mouse brain cortex and their regulation by sex steroids during aging

To examine the synthesis and phosphorylation of androgen receptor (AR) and their regulation by sex steroids, adult (24 weeks) and old (65 weeks) male and female mice were gonadectomized and administered with testosterone and estradiol. AR amount, synthesis and phosphorylation were measured in the brain cortex by immunoblotting and immunoprecipitation using antibody raised against rat AR transactivation domain (TAD) which was expressed in E. coli as a fusion protein. We found that the amount of AR was high in adult and declined in old mice of both sexes. Administration of testosterone and estradiol significantly down-regulated the level of AR in old male and adult female. Similarly, the rate of AR synthesis also declined with age. Exogenous treatment of gonadectomized mice with testosterone and estradiol reduced the extent of synthesis significantly in all groups except in old female. No sex-dependent variation was noticed either in the level or synthesis of AR. In contrast, the extent of phosphorylation was higher in old mice of both sexes as compared to their adult counterparts. Testosterone and estradiol supplementation resulted in remarkable increase in AR phosphorylation in all groups. Thus it is evident from our findings that the amount and synthesis of AR decrease but phosphorylation of AR increases in the brain cortex with advancing age of mice and they are regulated by testosterone and estradiol in age- and sex-specific manner.

Sex-specific alterations in chromatin conformation of the brain of aging mouse

Chromatin conformation has been analysed in the brain cortex of adult (24+/-2 weeks) and old (65+/-4 weeks) male and female mice. Nuclei purified from different groups of mice were digested with MNase and DNase I for varying time periods (0-90 min), and with endogenous endonucleases for 1 h. MNase and DNase I digestion kinetics showed that the percentage of acid solubility of chromatin was relatively lower in old than adult and in female than male. This was further supported by electrophoretic analysis of nuclease digested DNA fragments. When the nuclei were incubated with only Ca2+ or Mg2+, no endonuclease digestion was observed. However, under similar conditions, the liver DNA was cleaved substantially. When divalent cations were added together, they activated endogenous endonucleases and digested the brain chromatin. The activity of Ca2+/Mg2+-dependent endogenous endonucleases was higher in male than female. Thus the accessibility of chromatin to MNase, DNase I and endogenous endonucleases was higher in male than female, and MNase as well as DNase I were more active in adult than old. Such sex- and age-dependent conformation of chromatin may attribute to differential expression of genes in the mouse brain.

Sex steroids modulate the synthesis and phosphorylation of proteins in the brain cortex of aging mice

We have analysed the synthesis and phosphorylation of total cellular proteins and their modulation by sex steroids (testosterone and 17beta-estradiol) in the brain cortex of adult (25-28 weeks) and old (54-58 weeks) male and female AKR mice. The level of (35S) methionine incorporation in total proteins is comparatively higher in males than females. It declines significantly in older males but shows no difference with age in females. After gonadectomy, the extent of (35S) methionine incorporation decreases in adults but not in the old. The incorporation is induced remarkably by estradiol in males and by both sex steroids in females. Further analysis by fluorography shows several proteins, but only a few (66, 45 and 29 kDa) vary in levels significantly with age, sex and hormonal treatment. The data on phosphorylation of total cellular proteins by (32P) orthophosphate incorporation exhibit no age-dependent variation. However, it is reduced drastically by gonadectomy in adults. After the addition of testosterone, the extent of phosphorylation is enhanced significantly in adults but remains the same in the old of both sexes. Estradiol also increases this modification remarkably in males of both ages and adult females, but shows no effect in old females. These results suggest that both testosterone and estradiol modulate the synthesis and phosphorylation of brain cortex proteins in age- and sex-dependent manner. This leads to alterations in physiological activities of the animal.

Age-dependent degradation of amyloid precursor protein in the post-mortem mouse brain cortex

We have examined the degradation of amyloid precursor protein (APP) in the brain cortex of adult (24 +/- 2) and old (58 +/- 2) mice at different post-mortem time intervals (0, 1.5, 3, 6, 12 and 24 h). The brain cortex extract was prepared and processed for immunoblotting using antibodies against N-terminal 47-62 amino acids (Asp29) and central 301-316 amino acids containing Kunitz protease inhibitor (KPI) domain (Asp45) of APP. Asp29 (N-terminal) recognizes two bands of 140 and 112 kDa. The amount of 140 kDa is relatively higher in adult than old. The level of 112 kDa is 1.6 times lower in adult than old. It shows no remarkable change with varying post-mortem time. On the other hand, Asp45 (KPI) detects two bands of 110 and 116 kDa. While 116 kDa disappears rapidly after death of the animal, 110 kDa shows no remarkable change with different post-mortem periods. Further incubation of the disrupted tissue at 4 degrees C for 24 h and immunoblot analysis with Asp29 (N-terminal) shows 112 kDa in both ages but 58.5 kDa in adult and 70 kDa in old only. Analysis with Asp45 (KPI) shows only 54 kDa which increases after 3 h in adult but decreases significantly after 1.5 h and becomes undetectable at 24 h in old. Thus the present findings indicate that APP is degraded in a precise pattern and it depends on cellular intactness, post-mortem period and age of the animal.