Non-nuclear/////////Using the death-trap screening method devised by Vito et al. (1996) to screen a cDNA library from an occipital lobe of an AD patient brain, they identified a long cDNA that encoded a deduced 24-amino acid polypeptide, which they called humanin (HN). Hashimoto et al. (2001) found that the cDNA sequence of HN (GenBank AY029066), is 99% identical to the sequence of 16S mitochondrial ribosomal RNA (561010), which is mitochondrially encoded. The authors determined that the HN cDNA is mitochondrial 16S rRNA with a poly(A) tail, which makes it unlikely that the peptide encoded by the cDNA is naturally produced. However, the cDNA is also 99% identical to some nuclear-encoded human cDNAs, making it is likely that HN cDNA represents a nuclear transcribed mRNA and that the HN peptide is a natural product. Northern blot analysis detected expression of major 1.6- and minor 3.0- and 1.0-kb transcripts at high levels in heart, skeletal muscles, kidney, and liver, at lower but significant levels in brain and the gastrointestinal tract, and at barely detectable levels in the immune system. Hashimoto et al. (2001) determined that HN is secreted into the extracellular medium and acts on the outside of cells as an orphan ligand, and they suggested that there was a specific binding site on the cell surface.
General function
Ligand, Hormone
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Cellular localization
Secreted, Mitochondrial
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Ovarian function
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Mitochondrial humanin peptide acts as a cytoprotective factor in granulosa cell survival. Marvaldi C et al. (2021) Humanin (HN) is a short peptide involved in many biological processes such as apoptosis, cell survival, inflammatory response, and reaction to stressors such as oxidative stress between others. In the ovary, a correct balance between pro- and anti-apoptotic factors is crucial for folliculogenesis. In the follicular atresia, survival or death of granulosa cells is a critical process. The goal of this study was to evaluate the action of HN on granulosa cell fate. To explore endogenous HN function in the ovary, we used a recombinant baculovirus (BV) encoding a short-hairpin RNA targeted to silence HN (shHN). HN down-regulation modified ovarian histoarchitecture and increased apoptosis of granulosa cells. HN was also detected in a granulosa tumor cell line (KGN). Transduction of KGN cells with BV shHN resulted in HN down-regulation and increased apoptosis. On the other hand, treatment of KGN cells with exogenous HN increased cell viability and decreased apoptosis. In summary, these findings indicate that HN is a cytoprotective factor in granulosa cells of antral follicles, suggesting that this peptide would be involved in the regulation of folliculogenesis. Also, this peptide is a cytoprotective factor in KGN cells and therefore, it could be involved in granulosa tumor cell behavior.//////////////////
Humanin alleviates insulin resistance in polycystic ovary syndrome: a human and rat model-based study. Wang Y et al. (2021) Polycystic ovary syndrome (PCOS), the most common endocrine disorder in women of reproductive age, is characterized by hyperandrogenism and insulin resistance (IR); however, the pathogenesis of local ovarian IR in PCOS remains largely unclear. Humanin, a mitochondria-derived peptide, has been reported to be associated with IR. Our previous study confirmed that humanin is expressed in multiple cell types and is present in follicular fluid. However, it remains unknown whether humanin participates in the pathogenesis of local ovarian IR or whether humanin supplementation can improve IR in PCOS patients. In this study, we compared humanin concentrations in follicular fluid from PCOS patients with and without IR. We further investigated the effect of humanin analogue (HNG) supplementation on IR in a rat model of dehydroepiandrosterone-induced PCOS. Humanin concentrations in the follicular fluid were found to be significantly lower in PCOS patients with IR than in those without IR. HNG supplementation attenuated both the increases in the levels of fasting plasma glucose and fasting insulin in rats with PCOS and the decreases in phosphorylation of IRS1, PI3K, AKT, and GLUT4 proteins in the granulosa cells of these rats. Combined supplementation with HNG and insulin significantly improved glucose consumption in normal and humanin-siRNA-transfected COV434 cells. In conclusion, downregulated humanin in the ovaries may be involved in the pathogenesis of IR in PCOS, and exogenous supplementation with HNG improved local ovarian IR through modulation of the IRS1/PI3K/Akt signaling pathway in a rat model. This finding supports the potential future use of HNG as a therapeutic drug for PCOS.//////////////////
Humanin regulates oxidative stress in the ovaries of polycystic ovary syndrome patients via the Keap1/Nrf2 pathway. Wang Y et al. (2020) Polycystic ovary syndrome (PCOS) is the most common endocrinological pathology among women of reproductive age, whereas the pathogenesis is still not fully understood. Systemic and ovarian oxidative stress (OS) imbalance is a pivotal feature of PCOS. Humanin, a mitochondria derived peptide, has been reported to function as an antioxidant in cardiomyocytes, pancreatic beta cells, and other cells, but how this function is regulated remains unclear. In this study, we investigated whether humanin expression differs in the granulosa cells of PCOS patients versus controls, and whether humanin alleviates oxidative stress in PCOS ovaries. Sixteen PCOS patients and twenty-eight age and BMI-matched controls undergoing IVF were recruited, and their serum, follicular fluid and granulosa cells were collected for humanin analysis. Dehydroepiandrosterone-induced rat PCOS models, and vitamin K3 (vitK3)-induced OS COV434 cell lines were to investigate the mechanism. Humanin expression was significantly down-regulated in the ovaries of PCOS patients relative to those of non-PCOS patients. Exogenous humanin supplementation significantly attenuated body weight gain, ovarian morphological abnormalities, endocrinological disorders and ovarian and systemic OS in PCOS rat models. Our study further demonstrated that this attenuation effect was involved in the modulation of the Keap1/Nrf2 signalling pathway. In summary, this study reported for the first time that decreased expression of humanin in the granulosa cells was associated with oxidative imbalance in PCOS. Humanin alleviates oxidative stress in ovarian granulosa cells of PCOS patients via modulation of the Keap1/Nrf2 signaling pathway.//////////////////
Expression regulated by
LH
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Ovarian localization
Oocyte, Luteal cells, Follicular Fluid
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Follicular fluid humanin concentration is related to ovarian reserve markers and clinical pregnancy after IVF-ICSI: a pilot study. Rao M et al. (2018) Is humanin present in the human ovary and follicular fluid? What relationship exists between humanin concentration in the follicular fluid and ovarian reserve and clinical outcomes after IVF and intracytoplasmic sperm injection (ICSI)? Follicular fluid samples were collected from 179 patients undergoing their first IVF or ICSI cycle during oocyte retrieval. Ovarian tissues were collected from two patients undergoing surgery for ovarian cysts. Ovarian humanin localization was analysed using immunofluorescence staining. Expression of humanin in granulosa cells was confirmed by reverse transcription polymerase chain reaction (RT-PCR) analysis. Follicular fluid humanin levels were evaluated with enzyme-linked immunosorbent assay. Relationships between follicular fluid humanin levels and ovarian reserve markers and clinical outcomes were analysed. Strong humanin expression was found in the granulosa cells, oocytes and stromal cells of the ovary. Agarose gel electrophoresis of RT-PCR products showed rich humanin mRNA expression in human granulosa cells (119 bp). Follicular fluid humanin concentrations ranged from 86.40 to 417.60 pg/ml. They significantly correlated with FSH (r = -0.21; P < 0.01), LH (r = -0.18; P = 0.02), antral follicle count (r = 0.27; P < 0.01), anti-Müllerian hormone (r = 0.24; P = 0.03) and inhibin B (r = 0.46; P < 0.01) levels. Patients were subdivided into four groups according to follicular fluid humanin concentration quartiles (Q1-Q4). Patients in Q4 were more likely to achieve a pregnancy than Q1 (OR = 3.60; 95% CI 1.09 to 11.84). Humanin concentration in the follicular fluid was positively associated with ovarian reserve and clinical pregnancy rate.//////////////////
Identification of novel genes regulated by LH in the primate corpus luteum: insight into their regulation during the late luteal phase.
Kumar Yadav et al 2004 .
The process of luteinization, during which granulosa cells are transformed into luteal cells, is accompanied by dramatic changes in the response of luteal cells to LH. Although luteal cells require LH-cAMP signalling cascade for survival, whether these cells respond to trophic factors through changes in gene expression remains poorly characterized. In an attempt to characterize gonadotrophin (LH)-regulated gene expression in the bonnet monkey corpus luteum (CL), changes in gene expression after GnRH antagonist treatment to inhibit LH secretion, different stages of CL and during hCG-simulated early pregnancy were examined using differential display RT-PCR, Northern blot and semiquantitative RT-PCR analyses. We have identified seven non-redundant cDNA's whose expression were regulated by LH. The results show that inhibition of LH secretion not only leads to down-regulation in the expression of genes, e.g. low density lipoprotein (LDL) receptor and Aldose reductase, but expression of some of the genes was up-regulated, e.g. Humanin, RNA helicase, Lyric protein, Acidic ribosomal phosphoprotein and KIAA1750. mRNA levels of the genes identified as up-regulated after LH inhibition were higher during late compared to the early and mid-luteal phase CL, but treatment with hCG down-regulated their expressions. We conclude that we have identified novel genes (known and unknown) that are up or down-regulated by LH, and the results suggest that LH-mediated activation and repression of expression of many genes is central to the regulation of the structure and function of the CL in the monkey.