M R Sairam

McGill University, Montréal, Quebec, Canada

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Publications (187)751.53 Total impact

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    ABSTRACT: Recent studies suggest that bone marrow stem cells (BMSCs) are promising grafts to treat a variety of diseases, including reproductive dysfunction. Primary ovarian failure is characterized by amenorrhea and infertility in a normal karyotype female, with an elevated serum level of follicle-stimulating hormone (FSH) and a decrease level of estrogen caused by a mutation in FSH receptor (FSHR) gene. Currently, there is no effective treatment for this condition. The phenotype of FSHR (-/-) mouse, FORKO (follitropin receptor knockout), is a suitable model to study ovarian failure in humans. Female FORKO mice have elevated FSH, decreased estrogen levels, are sterile because of the absence of folliculogenesis, and display thin uteri and small nonfunctional ovaries. In this study, we determined the effects of BMSC transplantation on reproductive physiology in this animal model. Twenty four hours post BMSC transplantation, treated animals showed detectable estroidogeneic changes in daily vaginal smear. Significant increase in total body weight and reproductive organs was observed in treated animals. Hemotoxylin and eosin (H&E) evaluation of the ovaries demonstrated significant increase in both the maturation and the total number of the follicles in treated animals. The FSH dropped to 40-50% and estrogen increased 4-5.5 times in the serum of treated animals compared to controls. The FSHR mRNA was detected in the ovaries of treated animals. Our results show that intravenously injected BMSCs were able to reach the ovaries of FORKO mice, differentiate and express FHSR gene, make FSHR responsive to FSH, resume estrogen hormone production, and restore folliculogenesis.
    PLoS ONE 01/2012; 7(3):e32462. · 3.53 Impact Factor
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    H Zhang, X Chen, M R Sairam
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    ABSTRACT: We sought to characterise novel genes dysregulated by sex hormonal imbalances that induce obesity and metabolic disorder in a setting of oestrogen deficiency and androgen dominance in follicle-stimulating hormone receptor (For [also known as Fshr]) knockout female mice. Transcriptome analysis of mesenteric adipose tissue (MAT) of mutants revealed novel genes. One novel gene named Meda-7 was selected for study. Meda-7 was cloned from mouse and human adipose tissue; its expression, hormonal regulation and function were characterised. Mouse Meda-7 is richly expressed in deep visceral adipose tissue and encodes a 22 kDa secreted protein with 71% homology to human mesenteric oestrogen-dependent adipose gene- 7 (MEDA-7) protein. Both have six conserved cysteines like many cytokines. In obese patients, MEDA-7 is more abundant in omental than subcutaneous fat. Meda-7 is downregulated in For-knockout female MAT at 5 months (obese state) followed by steep upregulation at 9 months (prediabetic condition) when mutants progress towards the metabolic syndrome. Meda-7 is expressed predominantly in the stromal-vascular cell fraction. In this fraction,M1-proinflammatorymacrophages are rich in Meda-7. Meda-7 dysregulation in 5-month-old For-knockout MAT is restored by oestrogen, but treatment has no effect in older mutants. Overabundance of MEDA-7 in HEK-293 cells enhances cell proliferation via p42/44 mitogen-activated protein kinases. Secreted MEDA-7 attenuates insulin-stimulated glucose uptake in 3T3-L1 adipocytes, while downregulating glucose transporter-4 and upregulating both monocyte chemotactic protein-1 and suppressor of cytokine signalling-3. Downstream activity of the insulin signalling mediator, phospho-AKT, is also downregulated. MEDA-7 is a hormone-regulated adipokine/proinflammatory cytokine that is implicated in causing chronic inflammation, affecting cellular expansion and blunting insulin response in adipocytes.
    Diabetologia 06/2011; 54(9):2368-80. · 6.49 Impact Factor
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    ABSTRACT: In studying the age dependence and chronology of ovarian tumors in follicle stimulating hormone receptor knockout mice, we identified a novel ovarian tumor associated gene-12 (OTAG-12), which is progressively downregulated and maps to Chr. 8B3.3. OTAG-12 protein overexpression in mouse ovarian and mammary tumor cells suggested powerful anti-proliferative effects. In human epithelial ovarian cancers (OCs) and OC cell lines, OTAG-12 mRNA expression is downregulated in comparison with normal ovaries. Cloning and identification revealed that human OTAG-12 mapping to gene-rich Chr. 19p13.12 is expressed in three spliced forms: hOTAG-12a, hOTAG-12b and hOTAG-12c, of which b is predominant in the normal ovary. Functionally active hOTAG-12b is a simple protein with no disulfide bonds and a nuclear localization signal is present in all variants. Transfection of OTAG-12 variants in OC and tumorigenic HEK293 cells confirmed nuclear localization. hOTAG-12b overexpression in OC and HEK293 cells effectively suppressed cell growth, anchorage-dependent and independent colony formation followed by apoptosis, whereas hOTAG-12a and hOTAG-12c had no such effects. Deletion mutants identified the critical importance of carboxyl terminus for hOTAG-12b function. Doxycycline-inducible growth inhibition of HEK293 cells by hOTAG-12a was associated with effects on G2 cell cycle arrest and apoptosis induction. hOTAG-12b expression rendered tumorigenic cells more sensitive to four apoptotic stimuli including etoposide-a topoisomerase-II inhibitor. Doxycycline-induced hOTAG-12b expression blocked xenograft tumor growth in nude mice, whereas hOTAG-12a was ineffective. Although p53-pathway-dependent apoptotic agents could upregulate endogenous hOTAG-12b and p53 in UCI-101/107 OC cells, hOTAG-12b could also induce apoptosis in p53-null and platinum-resistant SKOV3 OC cells and Doxycycline-induced hOTAG-12b did not alter p53. Further study showed that hOTAG-12b increases mRNAs of pro-apoptotic genes such as BAD, GADD45α and CIEDB, while inhibiting anti-apoptotic NAIP and Akt1 expression, suggesting that hOTAG-12b-induced apoptosis might be p53-independent. These results indicate that hOTAG-12b is a putative ovarian tumor suppressor gene warranting further studies.
    Oncogene 02/2011; 30(25):2874-87. · 8.56 Impact Factor
  • J Libman, M S Gabriel, M R Sairam, A Zini
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    ABSTRACT: The aetiology of sperm DNA damage is likely multi-factorial with abnormal compaction of nuclear DNA, abortive apoptosis and oxidative stress implicated as potential causes of DNA damage. The objective of this study was to evaluate DNA damage in spermatozoa from wild-type (WT) and FSH receptor knock-out (FORKO) mice, compare the relative susceptibility of spermatozoa from these animals to oxidative DNA damage, and examine the protective effect of the antioxidant catalase on sperm DNA damage. Epididymal spermatozoa from FORKO mice (n = 5) and WT controls (n = 5) were extracted and incubated with or without catalase. Sperm DNA damage was assessed immediately after epididymal extraction (time 0 control) and following 2-h incubation at 37 °C. DNA damage was measured by the sperm chromatin structure assay and the results expressed as the %DNA fragmentation index or %DFI. Freshly retrieved epididymal spermatozoa from WT mice had a significantly lower mean (±SD) %DFI than that of FORKO mice (2.7 ± 1.8 vs. 6.4 ± 2.9%, p < 0.05). Prolonged (2-h) incubation of FORKO mice spermatozoa resulted in a significant increase in %DFI compared with the time 0 control (17.9 ± 9.2% vs. 6.4 ± 2.9%, respectively, p < 0.05) and the addition of catalase protected these spermatozoa from DNA damage (9.8 ± 4.1 vs. 17.9 ± 9.2%, respectively, p < 0.05). However, incubation of WT mice spermatozoa did not increase %DFI significantly (5.8 ± 5.0 vs. 2.7 ± 1.8, respectively, p > 0.05) and the addition of catalase (vs. no catalase) did not result in a significant reduction in %DFI (5.8 ± 5.0 vs. 7.7 ± 6.5%, respectively, p > 0.05). These data indicate that catalase may protect sperm nuclear DNA from oxidative stress in vitro. The data also demonstrate the differential susceptibility of WT and FORKO mice spermatozoa to oxidative stress.
    International Journal of Andrology 12/2010; 33(6):818-22. · 3.37 Impact Factor
  • J Aravindakshan, X L Chen, M R Sairam
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    ABSTRACT: Among gynecologic malignancies ovarian cancer is the deadliest and most difficult to detect at early stages. As ovarian tumors have long latency and are relatively more frequent in postmenopausal women, revealing chronological changes in model systems might help in the discovery of novel molecular targets and diagnostic biomarkers for disease detection and management. Follitropin receptor knockout (FORKO) mice with early and sustained sex steroid hormone disharmony develop various age-dependent ovarian abnormalities including increased incidence ovarian tumors in complete absence of ovulation. These mutants show various tumor cell types including those related to ovarian surface epithelium around 12-15 months of age. To explore why the FORKO mice develop ovarian tumors later in life, we assessed global gene expression changes during the pre-tumor period (at 8 months). Age-matched wild-type and FORKO mice were compared to gain a comprehensive view of genes that are misregulated, even before overt tumors appear in mutants. Applying a conservative 2-fold change to detect changes, our study identified 476 genes (338 upregulated and 138 downregulated) to be altered between 8-month-old FORKO and wild-type ovaries. Using Ingenuity Pathway Analysis (IPA), we found highly significant alterations in five functional networks in pre-tumor stage FORKO ovaries. Notably, the top network to change in 8-month-old FORKO ovaries was associated with functions implicated in immune system development and function. We selected 9 immune related genes that are reportedly altered in Epithelial Ovarian Cancer (EOC) in women and confirmed their expression and chronology of changes in FORKO ovaries before and after tumor development. Our data indicate that immune surveillance mechanisms are compromised with in a 4-month window of tumorigenic alterations. In addition, expression of previously unrecognized genes misregulated in the dysfunctional FORKO ovaries suggests mechanisms not yet appreciated to date. We propose that a better understanding of genes that change before overt tumors develop could provide useful insights into ovarian carcinogenesis and open the door to additional new targets for treating ovarian cancers.
    Molecular and Cellular Endocrinology 11/2010; 329(1-2):37-46. · 4.04 Impact Factor
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    ABSTRACT: A homozygous missense mutation, C566T, in the follicle stimulation hormone receptor (FSHR) gene has been linked to premature ovarian failure. The disease leads to infertility in a normal karyotype female with an elevated follicle stimulating hormone (FSH) and decreased serum estrogen level. Female mice carrying mutated FSHR gene, called follitropin receptor knockout (FORKO), display similar phenotype and are sterile because of a folliculogenesis block at a primary stage. We investigated the effects of bilateral intra-ovarian injection of an adenovirus expressing a normal copy of human FSHR on the reproductive system of 6-10 weeks female FORKO mice. Ad-LacZ was injected directly into each ovary of the control group. Animals were sacrificed at 2, 4, 8 and 12 weeks post-injection and tissues collected for evaluation. Treated mice showed estrogenic changes in daily vaginal smear whereas control animals remained fixated in the diestrus stage. Histological evaluation showed on average 26 +/- 4 follicles/ovary in treated group with 8 +/- 2 follicles at the antral stage compared with only 5 +/- 2 with zero follicles at antral stage in Ad-LacZ control mice. There was no significant change in serum level of progesterone, however, estrogen level increased 2-3-fold (P < 0.02) and FSH decreased by up to 50% (P < 0.04) in treated animals. FSHR mRNA was detected in the ovaries of the treated group. In conclusion, intra-ovarian injection of an adenovirus expressing human FSHR gene is able to restore FSH responsiveness and reinitiate ovarian folliculogenesis as well as resume estrogen production in female FORKO mice. Ad-LacZ injections indicate the absence of systemic viral dissemination or germ line transmission of adenovirus DNA to offspring.
    Molecular Human Reproduction 04/2010; 16(4):241-50. · 4.54 Impact Factor
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    Mary J Long, M Ram Sairam, Carolyn M Komar
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    ABSTRACT: PPARgamma is highly expressed in granulosa cells by 23 days post-partum (pp) and is down-regulated in response to the LH surge. We tested the hypothesis that high levels of FSH during the neonatal period trigger the expression of PPARgamma. To determine when PPARgamma expression is initiated, ovaries were collected from neonatal rats. Messenger RNA for PPARgamma was undetectable on day 1, low from days 5-14, and increased by day 19 pp (p < 0.05). PPARgamma was detected in select granulosa cells in primary/early secondary follicles. Messenger RNA for the FSH receptor was detected as early as day 1 and remained steady throughout day 19 pp. The FSH receptor was detected by immunoblot analysis in ovaries collected 1, 2, and 5-9 days pp. In a subsequent experiment, neonatal rats were treated with acyline (GnRH antagonist) which significantly reduced FSH (p < 0.05) but not levels of mRNA for PPARgamma. The role of FSH in the induction of PPARgamma expression was further assessed in ovarian tissue from FORKO mice. Both mRNA and protein for PPARgamma were identified in ovarian tissue from FORKO mice. In summary, the FSH/FSH receptor system is present in granulosa cells prior to the onset of expression of PPARgamma. Reducing FSH during the neonatal period, or the ability to respond to FSH, did not decrease expression of mRNA for PPARgamma. These data indicate that FSH is not a primary factor initiating the expression of PPARgamma and that other agents play a role in activating its expression in the ovary.
    Reproductive Biology and Endocrinology 12/2009; 7:145. · 2.41 Impact Factor
  • Rashmi Tiwari-Pandey, M Ram Sairam
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    ABSTRACT: We have previously shown that follicle-stimulating hormone receptor haploinsufficient mice undergo early reproductive senescence with alterations in ovarian structures. The objective of this study was to treat aging (7-8 months) +/- follicle-stimulating hormone receptor mice that are destined for reproductive failure with 2 selected antiandrogens, curcumin and flutamide, to counteract deleterious effects of mild hyperandrogenemia on the ovary and metabolism. Both compounds significantly downregulated the expression of ovarian androgen receptor protein and simultaneously reduced cyclooxygenase 2 protein in the ovary. Immunolocalization of bone morphogenetic protein-15 in the ovary was enhanced considerably by curcumin and partially by flutamide in treated mice. Improved structural changes were evident in zona pellucida of curcumin-treated ovaries. Flutamide reduced p450c-17 (cyp-17 protein) enzyme expression in thecal/interstitial cells, whereas increased expression of 3beta-hydroxysteroid dehydrogenase in thecal cells and granulosa-lutein cells of big follicles was apparent in curcumin-treated ovaries. Reduction in abdominal adiposity was greater in flutamide-treated mice. Taken together, our study allows the following conclusions: changes in ovarian histology and oocyte components as well as adipose tissue indicate the potential for reversing ovarian decline and metabolism because of mild hyperandrogenemia that occurs with aging in follicle-stimulating hormone receptor haploinsufficienct mice.
    Reproductive sciences (Thousand Oaks, Calif.) 04/2009; 16(6):539-50. · 2.31 Impact Factor
  • VINOD SINGH, M.R. SAIRAM
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    ABSTRACT: On the basis of the observation that in the hormonotoxin oLH-gelonin conjugation of the toxin occurs via the α-subunit of lutropin, an attempt was made to develop a general method for generation of similar hybrid proteins involving other glycoprotein hormones. In this approach sites suitable for conjugation would be first introduced into the α-subunit, hybridized with any native hormone specific β-subunit of choice (LH-β, FSH-β, TSH-β) following which the toxic component gelonin would be added on in the form of gelonin-S-S- α—β complex. Thus, thiolated lutropin α-subunit recombined well with free lutropin β-subunit, yielding a hybrid which was active in terms of receptor binding, immunoreactivity, and steroidogenic properties. However, subsequent conjugation with thiolated gelonin, a ribosome inactivating protein, resulted in dissociation of β-subunit from its non-covalent union with the thiolated α-subunit. It is concluded that the addition of positively charged gelonin at particular sites on the α-subunit led to the destabilization of the lutropin quaternary structure.
    European Journal of Allergy and Clinical Immunology 01/2009; 35(1):46 - 51. · 1.30 Impact Factor
  • VINOD SINGH, M. R. SAIRAM
    International journal of peptide and protein research 01/2009; 35(1):46-51.
  • M. R. SAIRAM
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    ABSTRACT: The subunits of ovine lutropin prepared by acid dissociation and salt precipitation were characterized by end group analysis, tryptic peptide mapping, SDS gel electrophoresis and biological activity. No evidence of internal peptide cleavage was found in the α subunit. The subunits possessed low activity. The α and β subunits recombined effectively to generate a complex that had full receptor binding activity and in vitro biological activity. The recombinants of subunits prepared by countercurrent distribution showed only 50% activity in both assays. The salt precipitation method α subunit could be completely reduced and reoxidized in the absence of denaturants. The reoxidized α subunit combines with the native β subunit generating full activity. However, this recombined hormone tends to lose activity with time, suggesting that the reoxidation may not fully restore the native structure of the reduced α subunit. The native lutropin α subunit effectively combined with follitropin β subunit generating complete follitropin activity.
    International journal of peptide and protein research 01/2009; 14(2):153-160.
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    ABSTRACT: Estrogen deficiency is associated with increased cardiovascular risk due, in part, to hypertension, endothelial dysfunction, obesity, and hypercholesterolemia. Underlying mechanisms for this remain unclear. Here, we investigated whether high-fat intake aggravates vascular dysfunction through oxidative stress and inflammation, which could predispose to cardiovascular injury in conditions of estrogen deficiency, such as menopause. We studied female homozygous follitropin receptor knock out (FORKO) mice, which have hormonal features of clinical menopause and hypertension and wild-type (WT) and heterozygote mice (HTZ), fed a standard or high-fat diet for 4 months. Vascular function and structure were evaluated in arterial segments by pressurized myography. Acetylcholine (ACh)-induced vasodilation was reduced in FORKO vs. WT mice (P < .001). N(varpi)-nitro-l-arginine-methyl-ester inhibited Ach-induced relaxation in all groups on normal chow and in WT and HTZ on high-fat diet (FD) but had no effect in fat-fed FORKO mice. Antioxidant cocktail (superoxide dismutase, catalase, Tempol) increased ACh responses only in high-fat diet FORKO mice (P < .05). Vascular media-to-lumen ratio was increased and reactive oxygen species (ROS) generation, nitrotyrosine formation, and plasma nitrite levels were augmented in fat-fed FORKO vs. FORKO on normal chow. High-fat diet did not influence vascular inflammatory responses in any group. Our data demonstrate that FORKO mice have altered nitric oxide-sensitive vasorelaxation and vascular remodeling, which are aggravated by high-fat diet. Underlying mechanisms for this may involve decreased NO formation and increased generation of ROS and nitrotyrosine. These findings suggest that high-fat intake potentiates vascular damage in estrogen-deficient states, an effect involving increased oxidative stress.
    Journal of the American Society of Hypertension 01/2009; 3(5):295-305. · 2.84 Impact Factor
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    ABSTRACT: Oxidative stress is implicated in menopause-associated hypertension and cardiovascular disease. The role of antioxidants in this process is unclear. We questioned whether the downregulation of thioredoxin (TRX) is associated with oxidative stress and the development of hypertension and target-organ damage (cardiac hypertrophy) in a menopause model. TRX is an endogenous antioxidant that also interacts with signaling molecules, such as apoptosis signal-regulated kinase 1 (ASK-1), independently of its antioxidant function. Aged female wild-type (WT) and follitropin receptor knockout (FORKO) mice (20-24 wk), with hormonal imbalances, were studied. Mice were infused with ANG II (400 ng x kg(-1) x min(-1); 14 days). Systolic blood pressure was increased by ANG II in WT (166+/-8 vs. 121+/-5 mmHg) and FORKO (176+/-7 vs. 115+/-5 mmHg; P<0.0001; n=9/group) mice. In ANG II-infused FORKO mice, cardiac mass was increased by 42% (P<0.001). This was associated with increased collagen content and augmented ERK1/2 phosphorylation (2-fold). Cardiac TRX expression and activity were decreased by ANG II in FORKO but not in WT (P<0.01) mice. ASK-1 expression, cleaved caspase III content, and Bax/Bcl-2 content were increased in ANG II-infused FORKO (P<0.05). ANG II had no effect on cardiac NAD(P)H oxidase activity or on O(2)(*-) levels in WT or FORKO. Cardiac ANG II type 1 receptor expression was similar in FORKO and WT. These findings indicate that in female FORKO, ANG II-induced cardiac hypertrophy and fibrosis are associated with the TRX downregulation and upregulation of ASK-1/caspase signaling. Our data suggest that in a model of menopause, protective actions of TRX may be blunted, which could contribute to cardiac remodeling independently of oxidative stress and hypertension.
    AJP Heart and Circulatory Physiology 08/2008; 295(4):H1481-8. · 4.01 Impact Factor
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    ABSTRACT: Estrogen is considered a major regulator of adipose tissue in females. Estrogen increases circulating levels of atrial natriuretic peptide (ANP), a hormone with renal and cardiovascular effects. The aim of this study was to determine the status of the natriuretic peptide system in female follitropin-receptor knockout (FORKO) mice that could be associated with obesity and hypertension observed in these mutants. Furthermore, estradiol treatment was used to reverse alterations observed. FORKO and wild-type (WT) mice received daily injections of estradiol for 4 d. On the fifth day, blood was collected for determination of plasma ANP levels, and selected tissues were collected for determination of ANP, natriuretic peptide receptor type-A (NPR-A) and type-C (NPR-C) gene expression by RT-PCR and binding of [(125)I]ANP by autoradiography. At 5 months of age, FORKO mice were heavier and had more adipose tissue than WT mice. FORKO mice had lower plasma ANP levels and atrial ANP gene expression and higher renal and adipocyte NPR-C gene expression than WT mice. Estradiol treatment reduced weight gain and increased atrial ANP synthesis as well as decreased ANP clearance NPR-C receptors, resulting in elevation of circulating ANP level. In conclusion, this study shows that FORKO females have an impaired natriuretic peptide system, which may contribute to the susceptibility of FORKO mice to developing age-related hypertension previously shown in these animals. This study establishes a relation between estrogen, adipose tissue, and ANP, which may have important implications in menopausal women.
    Endocrinology 04/2008; 149(3):1399-406. · 4.72 Impact Factor
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    ABSTRACT: Early obesity and late onset of insulin resistance associated with hormonal imbalances occur in FSH receptor-deficient follitropin receptor knockout female mice. This study tests the hypothesis that chronic high-fat diet aggravates obesogenic changes in a depot-specific manner and explores some molecular links of hormone imbalances with insulin resistance. In SV 129 mice, hormonal imbalances seem obligatory for exacerbation of diet-induced obesity. Visceral adiposity, glucose intolerance, and lipid disturbances in 9-month follitropin receptor knockout females were associated with decrease in adiponectin signaling. High-molecular-weight plasma adiponectin and adipose tissue adiponectin mRNA were decreased. Adiponectin receptors R1 and R2 mRNA was selectively altered in mesenteric fat but not periuterine fat. R2 decreased in the liver and R1 was higher in muscle. Whereas hepatic adenosine monophosphate T-activated protein kinase activity was down-regulated, both phosphoenolpyruvate carboxykinase and glucose-6-phosphatase enzymes were up-regulated. Longitudinally, diminishing sex hormone signaling in adipose tissue was associated with progressive down-regulation of adiponectin activity and gradual impaired glucose tolerance. Chronic high-fat diet in SV129 wild-type mice did not produce overt obesity but induced visceral fat depot changes accompanied by liver lipid accumulation, high cholesterol, and up-regulation of inflammation gene mRNAs. Thus, TNF-alpha, C-C motif chemokine receptor-2, and C-C motif chemokine ligand-2 were selectively elevated in mesenteric fat without altering glucose tolerance and adiponectin signaling. Our study highlights adiponectin signaling and regulation to be involved in hormone imbalance-induced insulin resistance and demonstrates selective visceral adipose depot alterations by chronic high-fat diet and induction of inflammatory genes.
    Endocrinology 01/2008; 148(12):5667-79. · 4.72 Impact Factor
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    ABSTRACT: The central nervous system is exposed to the chronic oxidative stress during aging when the endogenous defence weakens and the load of reactive oxygen species enhances. Sex hormones and heat shock proteins (Hsps) participate in these responses to stress. Their regulation is disturbed in aging. We assessed the expression of Hsps in hippocampus and cortex of follitropin receptor knockout (FORKO) mice, known to exhibit gender and age-dependent imbalance in sex steroids and gonadotropins. These imbalances could contribute to an impaired regulation of Hsps thereby increasing the risk of developing neurodegenerative disorders. Our study shows that, in the hippocampus the expression of Hsp70 and Hsp25 was reduced in 20-month-old FORKO mice. However, in the cortex both Hsps were significantly down regulated only in elderly females. There is a well-established co-regulation between Hsps and mitogen-activated protein kinases (MAPKs). Significant, gender-specific impairments in the translocation of phosphorylated ERK and JNK were found in the CNS structures in aged FORKO mice. Our results suggest that hormonal imbalances lead to a disturbed subcellular distribution of activated MAPKs which contribute to the impairments of signal transduction networks maintaining normal physiological functions in the cortex and hippocampus that are associated with neurodegenerative changes in aging.
    Experimental Gerontology 08/2007; 42(7):619-28. · 3.91 Impact Factor
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    ABSTRACT: Little is known about the behavior of the ovarian surface epithelium (OSE), which plays a central role in ovarian cancer etiology. It has been suggested that incessant ovulation causes OSE changes leading to transformation and that high gonadotropin levels during postmenopause activate OSE receptors, inducing proliferation. We examined the chronology of OSE changes, including tumor appearance, in a mouse model where ovulation never occurs due to deletion of follitropin receptor. Changes in epithelial cells were marked by pan-cytokeratin (CK) staining. Histologic changes and CK staining in the OSE increased from postnatal day 2. CK staining was observed inside the ovary by 24 days and increased thereafter in tumor-bearing animals. Ovaries from a third of aged (1 year) mutant mice showed CK deep inside, indicating cell migration. These tumors resembled serous papillary adenoma of human ovaries. Weak expression of GATA-4 and elevation of PCNA, cyclooxygenase-1, cyclooxygenase-2, and platelet-derived growth factor receptors alpha and beta in mutants indicated differences in cell proliferation, differentiation, and inflammation. Thus, we report that OSE changes occur long before epithelial tumors appear in FORKO mice. Our results suggest that neither incessant ovulation nor follicle-stimulating hormone receptor presence in the OSE is required for inducing ovarian tumors; thus, other mechanisms must contribute to ovarian tumorigenesis.
    Neoplasia (New York, N.Y.) 07/2007; 9(6):521-31. · 5.48 Impact Factor
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    ABSTRACT: Osteoporosis is a leading public health problem. Although a major cause in women is thought to be a decline in estrogen, it has recently been proposed that FSH or follitropin is required for osteoporotic bone loss. We examined the FSH receptor null mouse (FORKO mouse) to determine whether altered ovarian function could induce bone loss independent of FSH action. By 3 months of age, FORKO mice developed age-dependent declines in bone mineral density and trabecular bone volume of the lumbar spine and femur, which could be partly reversed by ovarian transplantation. Bilateral ovariectomy reduced elevated circulating testosterone levels in FORKO mice and decreased bone mass to levels indistinguishable from those in ovariectomized wild-type controls. Androgen receptor blockade and especially aromatase inhibition each produced bone volume reductions in the FORKO mouse. The results indicate that ovarian secretory products, notably estrogen, and peripheral conversion of ovarian androgen to estrogen can alter bone homeostasis independent of any bone resorptive action of FSH.
    Endocrinology 07/2007; 148(6):2613-21. · 4.72 Impact Factor
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    ABSTRACT: Genetically modified follitrophin receptor knockout female mice with total FSH-receptor (FSH-R) deletion are sterile and their combined estrogen deficiency-hyperandrogenemic status provides an experimental paradigm to study the effect of hormonal imbalances on ovarian function and metabolic alterations. Elevated LH levels causing hyperandrogenemia perturb normal folliculogenesis. To control diverse pathophysiology associated with hormonal imbalances, we investigated the effects of transplanting a single normal mouse ovary in young mutants. An intact FSH-R signalling system in the graft responded promptly to the up-regulated pituitary gonadotrophins circulating in the host mutant. Resumption of regular estrous cycles validated stimulation of uterine functions. Secretions from the viable functioning grafts partially corrected follicular abnormalities originally present in host ovaries. Stromal hyperplasia responsible for high ovarian LH-receptor and key enzymes in host thecal/interstitial complex and hyperandrogenemia was reduced in host ovaries. Increases in plasma estradiol and reduced LH and free testosterone re-established the negative-feedback system. Reduced android obesity and activation of mammary glands indicated the combined beneficial effects of normalized steroid hormones on target organs. These data provide evidence that ovarian transplantation in mutants corrects estrogen loss and hyperandrogenemia. However, correction of hormonal imbalances is not sufficient to fully restore effects of FSH-R loss in host granulosa cells.
    Molecular Human Reproduction 06/2007; 13(5):287-97. · 4.54 Impact Factor
  • M Ram Sairam, P Suresh Babu
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    ABSTRACT: The original concept (dogma) of a single FSH receptor entity coupling to G(s) protein to activate adenylate cyclase and producing cAMP as second messenger appears inadequate to explain pleiotropic actions of the hormone. The identification and expression of alternatively spliced gonadotropin receptors, suggest that alternative splicing could serve as a mechanism for creating receptor diversity. Studies focused on sheep and mouse gonadal tissues show that the single large gene of approximately 250kb is a modular structure whose pre-mRNA undergoes alternative splicing creating several subtypes (at least four FSH-R1 to R4 identified to date). With segments of the N-terminus that are identical different topographies are generated by differing carboxyl termini. The same gene thus produces receptor types with different motifs that can display dominant positive, dominant negative, growth factor/cytokine type and potentially soluble binding protein features. Functional relevance is shown by modulation of receptor variants during hormonal stimulation. Presence of equivalent segments of the gene in the human and bovine suggests conservation and predicts similarity in structures and function. Thus, the complex cellular biology of follitropin receptors that may interact differently with polymorphic forms (glycosylation variants) of FSH represents an intricate scheme to regulate hormone signaling.
    Molecular and Cellular Endocrinology 02/2007; 260-262:163-71. · 4.04 Impact Factor

Publication Stats

3k Citations
751.53 Total Impact Points

Institutions

  • 2003–2009
    • McGill University
      • • Lady Davis Institute for Medical Research
      • • Department of Pharmacology and Therapeutics
      Montréal, Quebec, Canada
  • 2001–2009
    • Institut de recherches cliniques de Montréal
      Montréal, Quebec, Canada
  • 1979–2009
    • Université de Montréal
      • Department of Medicine
      Montréal, Quebec, Canada
  • 2007
    • University of Ottawa
      Ottawa, Ontario, Canada
    • University of Zagreb
      • Department of Medical Biochemistry and Hematology
      Zagreb, Grad Zagreb, Croatia
  • 2006
    • KIMEP University
      Almaty, Almaty Qalasy, Kazakhstan
  • 1992–2001
    • Indian Institute of Science
      • Department of Biochemistry
      Bengalore, State of Karnataka, India
  • 1998
    • Instituto de Investigación Clínica de Occidente
      Zapopan, Jalisco, Mexico
    • Institut de Génétique et de Biologie Moléculaire et Cellulaire
      Strasburg, Alsace, France
  • 1981
    • Montreal Heart Institute
      Montréal, Quebec, Canada
  • 1972–1975
    • University of California, San Francisco
      • Division of Hospital Medicine
      San Francisco, California, United States