Estradiol regulates APP mRNA alternative splicing in the mice brain cortex

Biological Sex Disparities in Alzheimer's Disease

Alzheimer's disease is a highly complex and multifactorial neurodegenerative disorder, with age being the most significant risk factor. The incidence of Alzheimer's disease doubles every 5 years after the age of 65. Consequently, one of the major challenges in Alzheimer's disease research is understanding how the brain changes with age. Gaining insights into these changes could help identify individuals who are more prone to developing Alzheimer's disease as they age. Over the past 25 years, studies on brain aging have examined thousands of human brains to explore the neuronal basis of age-related cognitive decline. However, most of these studies have focused on adults over 60, often neglecting the critical menopause transition period. During menopause, women experience a substantial decline in ovarian sex hormone production, with a decrease of about 90% in estrogen levels. Estrogen is known for its neuroprotective effects, and its significant loss during menopause affects various biological systems, including the brain. Importantly, despite known differences in dementia risk between sexes, the impact of biological sex and sex hormones on brain aging and the development of Alzheimer's disease remains underexplored.

Entorhinal cortex vulnerability to human APP expression promotes hyperexcitability and tau pathology

Preventative treatment for Alzheimer's Disease (AD) is dire, yet mechanisms underlying early regional vulnerability remain unknown. In AD, one of the earliest pathophysiological correlates to cognitive decline is hyperexcitability, which is observed first in the entorhinal cortex. Why hyperexcitability preferentially emerges in specific regions in AD is unclear. Using regional, cell-type-specific proteomics and electrophysiology in wild-type mice, we uncovered a unique susceptibility of the entorhinal cortex to human amyloid precursor protein (hAPP). Entorhinal hyperexcitability resulted from selective vulnerability of parvalbumin (PV) interneurons, with respect to surrounding excitatory neurons. This effect was partially replicated with an APP chimera containing a humanized amyloid-beta sequence. EC hyperexcitability could be ameliorated by co-expression of human Tau with hAPP at the expense of increased pathological tau species, or by enhancing PV interneuron excitability in vivo. This study suggests early interventions targeting inhibitory neurons may protect vulnerable regions from the effects of APP/amyloid and tau pathology.

Entorhinal cortex vulnerability to human APP expression promotes hyperexcitability and tau pathology

Preventative treatment for Alzheimer's Disease is of dire importance, and yet, cellular mechanisms underlying early regional vulnerability in Alzheimer's Disease remain unknown. In human patients with Alzheimer's Disease, one of the earliest observed pathophysiological correlates to cognitive decline is hyperexcitability. In mouse models, early hyperexcitability has been shown in the entorhinal cortex, the first cortical region impacted by Alzheimer's Disease. The origin of hyperexcitability in early-stage disease and why it preferentially emerges in specific regions is unclear. Using cortical-region and cell-type-specific proteomics coupled with ex vivo and in vivo electrophysiology, we uncovered differential susceptibility to human-specific amyloid precursor protein (hAPP) in a model of sporadic Alzheimer's. Unexpectedly, our findings reveal that early entorhinal hyperexcitability may result from intrinsic vulnerability of parvalbumin (PV) interneurons, rather than the suspected layer II excitatory neurons. This vulnerability of entorhinal PV interneurons is specific to hAPP, as it could not be recapitulated with increased murine APP expression. However, partial replication of the findings could be seen after introduction of a murine APP chimera containing a humanized amyloid-beta sequence. Surprisingly, neurons in the Somatosensory Cortex showed no such vulnerability to adult-onset hAPP expression. hAPP-induced hyperexcitability in entorhinal cortex could be ameliorated by enhancing PV interneuron excitability in vivo. Co-expression of human Tau with hAPP decreased circuit hyperexcitability, but at the expense of increased pathological tau species. This study suggests early disease interventions targeting non-excitatory cell types may protect regions with early vulnerability to pathological symptoms of Alzheimer's Disease and downstream cognitive decline.

Association between the BCR-ABL gene transcripts and the laboratory hematological profile

Objective: This study describes the hematological parameters associated with the BCR-ABL gene transcripts in patients with chronic myeloid leukemia (CML). Methods: We reviewed the results of 100 detectable patients for one of the BCR-ABL gene transcripts. The eligibility criteria were based on the presence of one of the leukemic transcripts (b2a2, b3a2, and b2a2/b3a2) and complete epidemiological and hematological data. The data were obtained from the LabMaster computerized system. The Kruskal-Wallis test was used to compare the medians of the quantitative variables between the transcripts of the BCR-ABL gene and the chi-square test to compare the qualitative ones, adopting the p-value with a level of significance less than or equal to 0.05. Results: Forty-five patients (45%) presented the b2a2 transcript, 24 (24%) the b3a2 transcript and 31 (31%) a b2a2/b3a2 coexpression. Individuals who expressed the b3a2 transcript had higher leukocyte counts and platelet levels, but we found no differences compared with individuals who expressed the other transcript. Conclusion: In this study, the BCR-ABL gene transcripts did not influence the hematological parameters of patients with CML.

Androgen Therapy in Neurodegenerative Diseases

Neurodegenerative diseases, including Alzheimer disease (AD), Parkinson disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), and Huntington disease, are characterized by the loss of neurons as well as neuronal function in multiple regions of the central and peripheral nervous systems. Several studies in animal models have shown that androgens have neuroprotective effects in the brain and stimulate axonal regeneration. The presence of neuronal androgen receptors in the peripheral and central nervous system suggests that androgen therapy might be useful in the treatment of neurodegenerative diseases. To illustrate, androgen therapy reduced inflammation, amyloid-β deposition, and cognitive impairment in patients with AD. As well, improvements in remyelination in MS have been reported; by comparison, only variable results are observed in androgen treatment of PD. In ALS, androgen administration stimulated motoneuron recovery from progressive damage and regenerated both axons and dendrites. Only a few clinical studies are available in human individuals despite the safety and low cost of androgen therapy. Clinical evaluations of the effects of androgen therapy on these devastating diseases using large populations of patients are strongly needed.

Association of BCR/ABL transcript variants with different blood parameters and demographic features in Iraqi chronic myeloid leukemia patients

Background

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm characterized by the presence of BCR‐ABL fusion gene (GenBank accession NC_000022.11). In the vast majority of CML patients, the typical subtype of BCR‐ABL transcript are b3a2, b2a2 or both. The aim of this study was to determine the different subtypes of BCR‐ABL transcript and their impact on the demographic and hematological parameters in Iraqi patients with CML.

Methods

One hundred patients with chronic phase CML (11 newly diagnosed and 89 imatinib‐resistant) were enrolled in this study. Ribonucleic acid (RNA) was extracted from leukocytes, and complementary DNA was created using reverse transcriptase polymerase chain reaction technique. A multiplex polymerase chain reaction with four specific primers was used to determine the BCR‐ABL fusion subtypes in each patient.

Results

Male to female ratio was 1.38:1. Fifty‐nine patients expressed b3a2 transcript, whereas 39 of the remaining cases were positive for b2a2 variant. One case expressed b2a3 transcript, while the last case coexpressed the two subtypes of mRNA b3a2/b2a2. Male and female were significantly associated with b3a2 and b2a2 subtypes, respectively. The b3a2 subtype showed higher total leukocyte count than b2a2 subgroup, while b2a2 variant demonstrated significantly elevated platelet counts compared to those with b3a2 transcript. A significantly higher plateletcrit percentage (PCT%) was found in patients with b2a2 transcript whereas.

Conclusions

The testified Iraqi group expressed M‐BCR‐ABL type with preponderance of b3a2 over b2a2 subtype. There was a gender‐skewed distribution in BCR‐ABL transcript types with b3a2 transcript more prevalent in males. The type of BCR‐ABL transcript is reflected by different leukocyte and platelet counts at diagnosis, which might represent a distinct phenotype and disease biology.

An exploratory investigation of brain-selective estrogen treatment in males using a mouse model of Alzheimer's disease

Estrogens are neuroprotective, and studies suggest that they may mitigate the pathology and symptoms of Alzheimer's disease (AD) in female models. However, central estrogen effects have not been examined in males in the context of AD. The purpose of this follow-up study was to assess the benefits of a brain-selective 17β-estradiol estrogen prodrug, 10β,17β-hydroxyestra-1,4-dien-3-one (DHED), also in the male APPswe/PS1dE9 double-transgenic mouse model of the disease. After continuously exposing 6-month old animals to DHED for two months, their brains showed decreased amyloid precursor and amyloid-β protein levels. The DHED-treated APPswe/PS1dE9 double transgenic subjects also exhibited enhanced performance in a cognitive task, while 17β-estradiol treatment did not reach statistical significance. Taken together, data presented here suggest that DHED may also have therapeutic benefit in males and warrant further investigations to fully elucidate the potential of targeted estrogen therapy for a gender-independent treatment of early-stage AD.

Sex Hormone Decline and Amyloid β Synthesis, Transport and Clearance in the Brain

Sex hormones (SH) are essential regulators of the central nervous system. The decline in SH levels along with ageing may contribute to compromised neuroprotection and set the grounds for neurodegeneration and cognitive impairments. In Alzheimer's disease, besides other pathological features, there is an imbalance between amyloid β (Aβ) production and clearance, leading to its accumulation in the brain of older subjects. Aβ accumulation is a primary cause for brain inflammation and degeneration, as well as concomitant cognitive decline. There is mounting evidence that SH modulate Aβ production, transport and clearance. Importantly, SH regulate most of the molecules involved in the amyloidogenic pathway, their transport across brain barriers for elimination, and their degradation in the brain interstitial fluid. This review brings together data on the regulation of Aβ production, metabolism, degradation and clearance by SH.

Danggui-Shaoyao-San Improves Learning and Memory in Female SAMP8 via Modulation of Estradiol

Previous studies showed that Danggui-Shaoyao-San (DSS), a traditional Chinese medicinal prescription, could alleviate cognitive dysfunction of Alzheimer's disease (AD) patients. However, the mechanisms remain unclear; we have now examined the effect of DSS on SAMP8 and elucidated the possible mechanism. Animals were treated with DSS for 2 months, and step-down test and Morris water maze (MWM) test were used to evaluated cognitive abilities. The estradiol (E2), NO, and glycine in blood plasma or in hippocampus were detected to explore the possible mechanisms. The latency of SAMP8 in step-down test was shorter than that of age-matched SAMR1, and DSS increased the latency especially in female animals. In MWM test, we got similar results; SAMP8 spent more time to find the platform, and DSS decreased the time before finding the platform, with little effect on swim velocity, during the training sessions. During test session, DSS increased the time spent in target quadrant especially in female SAMP8. In female SAMP8, plasma E2, NO, and glycine were elevated in plasma or hippocampus tissue. In conclusion, DSS could ameliorate deterioration of cognition in SAMP8, especially in female animals. Increasing E2, NO, and glycine might contribute to the cognitive improvement effect of DSS in female SAMP8.

The amyloid precursor protein: a biochemical enigma in brain development, function and disease

For 20 years the amyloid cascade hypothesis of Alzheimer disease (AD) has placed the amyloid-β peptide (Aβ), formed from the amyloid precursor protein (APP), centre stage in the process of neurodegeneration. However, no new therapeutic agents have reached the clinic through exploitation of the hypothesis. The APP metabolites, including Aβ, generated by its proteolytic processing, have distinct physiological functions. In particular, the cleaved intracellular domain of APP (AICD) regulates expression of several genes, including APP itself, the β-secretase BACE-1 and the Aβ-degrading enzyme, neprilysin and this transcriptional regulation involves direct promoter binding of AICD. Of the three major splice isoforms of APP (APP695, APP751, APP770), APP695 is the predominant neuronal form, from which Aβ and transcriptionally-active AICD are preferentially generated by selective processing through the amyloidogenic pathway. Despite intensive research, the normal functions of the APP isoforms remain an enigma. APP plays an important role in brain development, memory and synaptic plasticity and secreted forms of APP are neuroprotective. A fuller understanding of the physiological and pathological actions of APP and its metabolic and gene regulatory network could provide new therapeutic opportunities in neurodegeneration, including AD.

Gender, sex steroid hormones, and Alzheimer's disease

Age-related loss of sex steroid hormones is a established risk factor for the development of Alzheimer's disease (AD) in women and men. While the relationships between the sex steroid hormones and AD are not fully understood, findings from both human and experimental paradigms indicate that depletion of estrogens in women and androgens in men increases vulnerability of the aging brain to AD pathogenesis. We review evidence of a wide range of beneficial neural actions of sex steroid hormones that may contribute to their hypothesized protective roles against AD. Both estrogens and androgens exert general neuroprotective actions relevant to a several neurodegenerative conditions, some in a sex-specific manner, including protection from neuron death and promotion of select aspects of neural plasticity. In addition, estrogens and androgens regulate key processes implicated in AD pathogenesis, in particular the accumulation of β-amyloid protein. We discuss evidence of hormone-specific mechanisms related to the regulation of the production and clearance of β-amyloid as critical protective pathways. Continued elucidation of these pathways promises to yield effective hormone-based strategies to delay development of AD.

Traumatic brain injury: a risk factor for Alzheimer's disease

Traumatic brain injury (TBI) constitutes a major global health and socio-economic problem with neurobehavioral sequelae contributing to long-term disability. It causes brain swelling, axonal injury and hypoxia, disrupts blood brain barrier function and increases inflammatory responses, oxidative stress, neurodegeneration and leads to cognitive impairment. Epidemiological studies show that 30% of patients, who die of TBI, have Aβ plaques which are pathological features of Alzheimer's disease (AD). Thus TBI acts as an important epigenetic risk factor for AD. This review focuses on AD related genes which are expressed during TBI and its relevance to progression of the disease. Such understanding will help to diagnose the risk of TBI patients to develop AD and design therapeutic interventions.

Sex hormones, aging, and Alzheimer's disease

A promising strategy to delay and perhaps prevent Alzheimer's disease (AD) is to identify the age-related changes that put the brain at risk for the disease. A significant normal age change known to result in tissue-specific dysfunction is the depletion of sex hormones. In women, menopause results in a relatively rapid loss of estradiol and progesterone. In men, aging is associated with a comparatively gradual yet significant decrease in testosterone. We review a broad literature that indicates age-related losses of estrogens in women and testosterone in men are risk factors for AD. Both estrogens and androgens exert a wide range of protective actions that improve multiple aspects of neural health, suggesting that hormone therapies have the potential to combat AD pathogenesis. However, translation of experimental findings into effective therapies has proven challenging. One emerging treatment option is the development of novel hormone mimetics termed selective estrogen and androgen receptor modulators. Continued research of sex hormones and their roles in the aging brain is expected to yield valuable approaches to reducing the risk of AD.

Sex hormones, aging, and Alzheimer's disease

A promising strategy to delay and perhaps prevent Alzheimer's disease (AD) is to identify the age-related changes that put the brain at risk for the disease. A significant normal age change known to result in tissue-specific dysfunction is the depletion of sex hormones. In women, menopause results in a relatively rapid loss of estradiol and progesterone. In men, aging is associated with a comparatively gradual yet significant decrease in testosterone. We review a broad literature that indicates age-related losses of estrogens in women and testosterone in men are risk factors for AD. Both estrogens and androgens exert a wide range of protective actions that improve multiple aspects of neural health, suggesting that hormone therapies have the potential to combat AD pathogenesis. However, translation of experimental findings into effective therapies has proven challenging. One emerging treatment option is the development of novel hormone mimetics termed selective estrogen and androgen receptor modulators. Continued research of sex hormones and their roles in the aging brain is expected to yield valuable approaches to reducing the risk of AD.

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.

Protective actions of sex steroid hormones in Alzheimer's disease

Risk for Alzheimer's disease (AD) is associated with age-related loss of sex steroid hormones in both women and men. In post-menopausal women, the precipitous depletion of estrogens and progestogens is hypothesized to increase susceptibility to AD pathogenesis, a concept largely supported by epidemiological evidence but refuted by some clinical findings. Experimental evidence suggests that estrogens have numerous neuroprotective actions relevant to prevention of AD, in particular promotion of neuron viability and reduction of beta-amyloid accumulation, a critical factor in the initiation and progression of AD. Recent findings suggest neural responsiveness to estrogen can diminish with age, reducing neuroprotective actions of estrogen and, consequently, potentially limiting the utility of hormone therapies in aged women. In addition, estrogen neuroprotective actions are also modulated by progestogens. Specifically, continuous progestogen exposure is associated with inhibition of estrogen actions whereas cyclic delivery of progestogens may enhance neural benefits of estrogen. In recent years, emerging literature has begun to elucidate a parallel relationship of sex steroid hormones and AD risk in men. Normal age-related testosterone loss in men is associated with increased risk to several diseases including AD. Like estrogen, testosterone has been established as an endogenous neuroprotective factor that not only increases neuronal resilience against AD-related insults, but also reduces beta-amyloid accumulation. Androgen neuroprotective effects are mediated both directly by activation of androgen pathways and indirectly by aromatization to estradiol and initiation of protective estrogen signaling mechanisms. The successful use of hormone therapies in aging men and women to delay, prevent, and or treat AD will require additional research to optimize key parameters of hormone therapy and may benefit from the continuing development of selective estrogen and androgen receptor modulators.

Correlation of BCR/ABL transcript variants with patients' characteristics in childhood chronic myeloid leukaemia

BACKGROUND AND OBJECTIVE

The characteristic chromosomal translocation t(9;22)(q34;q11) in chronic myeloid leukaemia (CML) mainly results in the two different BCR/ABL fusion transcripts b2a2 or b3a2. Both transcript variants can occur simultaneously due to alternative splicing of the b3a2 transcript. Conflicting results have been reported on the influence of the transcripts on haematological findings at diagnosis and the course of the disease in adults while data concerning these topics on childhood CML are still missing. This paper reports on a correlation of BCR/ABL transcript variants with patients' characteristics in childhood CML.

DESIGN AND METHODS

Transcript types were determined in 146 paediatric patients with CML enrolled in trial CML-paed-I. Fifty-five patients (38%) expressed b2a2, 53 patients (36%) b3a2 and 38 patients (26%) both transcripts, respectively. These findings were correlated with patients' characteristics (sex, age, WBC, Hb, platelet count, hepatosplenomegaly, etc.) assessed at diagnosis.

RESULTS

While the co-expression of both transcripts was evenly distributed among genders [b2a2 + b3a2: 22 females (28%), 16 males (24%)] a highly significant difference (P = 0.007) was found concerning the expression of the b2a2 transcript [34 male (51%) vs. 21 female (27%)] and vice versa of the b3a2 transcript [17 male (25%) vs. 36 female (45%)]. High platelet counts and the combination of high platelet counts in conjunction with pronounced leukocytosis were observed more often in patients expressing the b3a2 transcript.

CONCLUSIONS

These findings demonstrate that in children like in adults specific BCR/ABL transcript types present at diagnosis are associated with distinct haematological alterations (e.g. a high platelet count with the transcript b3a2). However, the sex-dependent skewed distribution of the BCR/ABL transcript types observed so far in this paediatric cohort only deserves further investigation.

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.

PS1 expression is downregulated by gonadal steroids in adult mouse brain

Mutations in presenilin (PS) 1 and PS2 genes are associated with early onset (< or =65 years) of Alzheimer's disease (AD). PS1 is involved in gamma-secretase mediated cleavage of beta-amyloid precursor protein (APP), but its regulation is poorly understood. Sex steroids influence APP cleavage pathways resulting in reduced burden of both intra- and extra-cellular nonamyloidogenic products. As gonadal hormones are implicated in AD and their levels change with age, we have analyzed the effect of 17beta-estradiol and testosterone on PS1 expression in the cerebral cortex of adult and old AKR mice of both sexes. Northern and Western-blot analysis revealed that PS1 mRNA and protein expression followed similar pattern of regulation. PS1 expression was downregulated by 17 beta-estradiol and testosterone in the cerebral cortex of females and adult male, but upregulated in old male mice. Such sex-dependent regulation of PS1 expression during aging by gonadal steroids might account for the PS-related brain functions.

A role for SC35 and hnRNPA1 in the determination of amyloid precursor protein isoforms

The beta-amyloid peptide (Abeta) that accumulates in senile plaques in Alzheimer's disease is formed by cleavage of the amyloid precursor protein (APP). The APP gene has several intronic Alu elements inserted in either the sense or antisense orientation. In this study, we demonstrate that binding of SC35 and hnRNPA1 to Alu elements on either side of exon 7 in the transcribed pre-mRNA is involved in alternative splicing of APP exons 7 and 8. Neuronal cells transfected with the full-length form of APP secrete higher levels of Abeta than cells transfected with the APP695 isoform lacking exons 7 and 8. Finally, we show that treatment of neuronal cells with estradiol results in increased expression of APP695, SC35 and hnRNPA1, and lowers the level of secreted Abeta. An understanding of the regulation of splicing of APP may lead to the identification of new targets for treating Alzheimer's disease.

Coregulators: transducing signal from transcription to alternative splicing

Cells respond to many external stimuli by modulating gene expression. A key step in this regulation is the control of transcription, which determines the concentrations of pre-mRNA that are produced. A second level of control involves maturation of pre-mRNAs; many are alternatively spliced, which changes the exon content of transcripts and therefore the 'message' of the genes. Recent data indicate that the two control levels are linked. Here, we describe how transcriptional regulators and coregulators influence alternative splicing, with a focus on genes that are controlled by steroid hormones. Recent technical advances that help to elucidate the impact of stimuli on the exon content of regulated gene transcripts are also discussed.

Age and gender-dependent alternative splicing of P/Q-type calcium channel EF-hand

Ca(v)2.1 Ca(2+) channels (P/Q-type), which participate in various key roles in the CNS by mediating calcium influx, are extensively spliced. One of its alternatively-spliced exons is 37, which forms part of the EF hand. The expression of exon 37a (EFa form), but not exon 37b (EFb form), confers the channel an activity-dependent enhancement of channel opening known as Ca(2+)-dependent facilitation (CDF). In this study, we analyzed the trend of EF hand splice variant distributions in mouse, rat and human brain tissues. We observed a developmental switch in rodents, as well as an age and gender bias in human brain tissues, suggestive of a possible role of these EF hand splice variants in neurophysiological specialization. A parallel study performed on rodent brains showed that the data drawn from human and rodent tissues may not necessarily correlate in the process of aging.

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.

Sex influences on cholinesterase inhibitor treatment in elderly individuals with alzheimer's disease

BACKGROUND

The second generation of cholinesterase inhibitors (ChEIs) is approved in the United Kingdom for the treatment of mild to moderate Alzheimer's disease (AD). The UK National Institute of Clinical Excellence has raised questions, however, about whether ChEIs are cost-effective for the treatment of dementia. To address these concerns, it is important to identify factors that predict which patients may have the best response to ChEl treatment.

OBJECTIVE

We reviewed animal studies and human clinical studies to address whether sex can predict and influence the response to ChEI treatment based on differences in neuroanatomy, pharmacokinetics, and prevalence of dementia.

METHODS

Relevant articles examining the use of ChEIs in humans with dementia (especially in AD) and in animals were identified through searches of several databases, including MEDLINE, PubMed, and EMBASE for general medical topics, the Cochrane Controlled Clinical Trials Register and CINAHL DIRECT for nursing and allied health issues, and PsycLIT for reviews of psychology and psychiatry topics (1980 June 2006). Articles reviewed were limited to those that discussed the use of ChEIs in relation to sex.

RESULTS

Animal studies have produced a substantial amount of evidence to support the hypothesis that sex may influence the response to ChEIs and, in particular, that testosterone may play a significant role in producing this difference by its influence on the entry of ChEIs into the brain. The results of clinical studies in humans, on the other hand, have been mixed. Two double-label and open-label clinical studies suggested that there may be a 3-way interaction between apolipoprotein E genotype, sex, and tacrine (range, P = 0.03 to P = 0.05). Seven double-blind, open-label clinical trials and 13 case studies of donepezil, rivastigmine, and galantamine produced little evidence of an association between treatment outcomes (as measured with clinical rating scales) and sex, although in an open-label 2-year study in women with AD treated with donepezil, women had lower mortality rates than men (10% and 20%, respectively; P = 0.003). One study produced weak evidence that women treated with ChEIs may experience more adverse effects than men, but this may have been attributable to low body weight rather than to sex differences.

CONCLUSIONS

A substantial relation has not been established between sex and the second-generation ChEIs currently used in clinical settings for the treatment of AD. If an interaction between sex and ChEI treatment does exist, as suggested in 10 of the studies we analyzed, it is likely to be small and subtle, with much individual variation, as is the case with most neurologic sex differences. Nevertheless, sexual dimorphism in response to ChEI therapy warrants further investigation, especially in regard to its role in the development of novel AD therapies.

Strategies for examination of Alzheimer’s disease amyloid precursor protein isoforms

We describe a proteomics procedure using bioinformatics, immunoprecipitation, two-dimensional gel electrophoresis, Western blotting, in-gel digestion, LC-MS, MALDI-MS, and MS-MS for isolation and identification of amyloid precursor protein (APP) isoforms APP695, APP751, and APP770. Retinoic acid-induced Ntera 2 cell line, derived from a human teratocarcinoma cells, was the in-vitro source of APP. Initial isolation of whole APP was performed by immunoprecipitation, using AB10, a monoclonal antibody raised to amino acids 1-17 of the beta-amyloid peptide sequence, which is present in all three alpha secretase-cleaved isoforms of interest. The next stage was separation of whole APP into its isoform components by two-dimensional gel electrophoresis. Because of low APP concentrations, detection by the usual staining methods, for example Sypro Ruby, able to detect low picomole concentrations, did not enable visualisation of the isoforms. Western analysis, however, enabled primary detection of APP, because of the inherent sensitivity of antibodies raised to specific isoform regions. This initial visualization acted as a template for excision of isoforms from 2D gels, which were then subjected to peptide mass mapping. Initial theoretical digestion of each isoform revealed the presence of specific peptides, which were then used as "tags" for isoform detection.

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.