AN important gene in autophagy.///////////////Microtubule-associated proteins MAP1A and MAP1B constitute nearly half of the mass of all the microtubule associated proteins that copurify with brain microtubules and are thought to be involved in neurite formation and stabilization.. MAP1A and MAP1B are each composed of a heavy chain and multiple light-chain subunits. The light chain, MAP1ALC3, is a component of both MAP1A and MAP1B microtubule-binding complexes (Mann and Hammarback 1996 ).
NCBI Summary:
MAP1A and MAP1B are microtubule-associated proteins which mediate the physical interactions between microtubules and components of the cytoskeleton. MAP1A and MAP1B each consist of a heavy chain subunit and multiple light chain subunits. The protein encoded by this gene is one of the light chain subunits and can associate with either MAP1A or MAP1B. Two transcript variants encoding different isoforms have been found for this gene. The expression of variant 1 is suppressed in many tumor cell lines, suggesting that may be involved in carcinogenesis. [provided by RefSeq, Feb 2012]
General function
Microtubule binding
Comment
Cigarette Smoke Exposure Elicits Increased Autophagy and Dysregulation of Mitochondrial Dynamics in Murine Granulosa Cells. Gannon AM et al. Cigarette smoking is a lifestyle behavior associated with significant adverse health effects including subfertility and premature ovarian failure. Cigarette smoke contains a number of chemicals, many of which are involved in the generation of reactive oxygen species, which can lead to apoptosis and autophagy. Autophagy is a fundamental process that removes damaged organelles and proteins through lysosomal degradation. The relevance of autophagy to toxicant-induced changes in ovarian function is largely unexplored. Previously, we reported that exposure to cigarette smoke causes follicle loss, oxidative stress, activation of the autophagy pathway, and a decrease in manganese superoxide dismutase expression (which points to altered mitochondrial function). Therefore, our objective was to test whether cigarette smoke exposure results in the dysregulation of mitochondrial repair mechanisms leading to loss of follicles via autophagy-mediated granulosa cell death. In this study, mice were exposed to cigarette smoke or room air for 8 weeks. The expression of genes and proteins of autophagy and mitochondrial repair factors were measured using quantitative real time PCR and Western blot, immunohistochemistry and ELISA. Increased expression of parkin and decreased expression of the mitofusins suggest that cigarette smoke exposure triggers mitochondrial damage. Moreover, the autophagy cascade proteins, BECN1 and LC3, were up-regulated, while the antagonist BCL2 was down-regulated following treatment. Taken together, our results suggest cigarette smoke exposure induces dysfunction of mitochondrial repair mechanisms, leading to autophagy-mediated follicle death.
Differential expression of programmed cell death on the follicular development in normal and miniature pig ovary. Kim SH et al. Follicles are important in oocyte maturation. Successful estrous cycle requires remodeling of follicular cells, and proper execution of programmed cell death is crucial for normal follicular development. The objectives of the present study were to understand programmed cell death during follicle development, to analyze the differential follicle development patterns, and to assess the patterns of apoptosis and autophagy expression during follicle development in normal and miniature pigs. Through the analysis of differential patterns of programmed cell death during follicular development in porcine, MAP1LC3A, B and other autophagy-associated genes (ATG5, mTOR, Beclin-1) were found to increase in normal pigs, while it decreased in miniature pigs. However, for the apoptosis-associated genes, progression of genes during follicular development increased in miniature pigs, while it decreased in normal pigs. Thus, results show that normal and miniature pigs showed distinct patterns of follicular remodeling manifesting that programmed cell death largely depends on the types of pathway during follicular development (Type II or autophagy for normal pigs and Type I or apoptosis for miniature pigs).
Cellular localization
Cytoplasmic
Comment
Ovarian function
Follicle atresia, Luteolysis, Early embryo development
Comment
Induction of apoptotic cell death via accumulation of autophagosomes in rat granulosa cells. Choi J et al. This study evaluated the effect of autophagosome accumulation on apoptotic cell death in granulosa cells from developing follicles. Our results indicate that the accumulation of autophagosomes induces apoptotic cell death of granulosa cells through decreased bcl-2 expression and subsequent caspase activation.
Autophagy is used as a survival program in unfertilized sea urchin eggs that are destined to die by apoptosis after inactivation of MAPK1/3 (ERK2/1). Houel-Renault L 2013 et al.
A high MAPK1/3 (also known as ERK2/1, respectively) activity, preventing spontaneous activation, is essential to maintain cell cycle arrest of mature oocytes of mammals, frogs or invertebrates such as starfish. Mature oocytes would undergo a 'suicide'-like cell death if not fertilized. We previously have reported that downregulation of MAPK1/3 in unfertilized sea urchin eggs induces a calcium-dependent entry into mitosis. We show here that this event is followed by a series of pseudo-mitotic cell cycles associated with transient Cai increases, preceding CASP3/caspase-3 activation and apoptosis. However, cell death was delayed after inhibition of the Cai transients or of cyclin-dependent kinases (CDK), with roscovitine. In these conditions, eggs enter an autophagy program as suggested by detection of processed LC3B by western blot, immunofluorescence and immunogold staining, visualization of autophagy vesicles by electron microscopy, and an increase in acidic vesicular organelles (AVOs). We found that bafilomycin A 1 or an association of leupeptin and pepstatin, which are widely used to study autophagy, may act upon calcium signaling or cell cycle events, respectively, and not only on autophagy events. Finally, inhibition of PtdIns 3-kinase with wortmannin or LY294002 powerfully stimulated cell death of unfertilized eggs, which suggests that this activity does not negatively regulate autophagy as is often reported, but rather stimulates survival in unfertilized eggs. We suggest that apoptosis of unfertilized eggs is the consequence of an aberrant short attempt of development that occurs if MAPK1/3 is inactivated, but these eggs can use autophagy as a survival program when the cell cycle is blocked.
/////////////////////////
The Role of Autophagy in Corpus Luteum Regression in the Rat. Choi J et al. Autophagy is associated with luteal cells death during regression of the corpus luteum (CL) in some species. However, the involvement of autophagy or the association between autophagy and apoptosis in CL regression are largely unknown. Therefore, we investigate the role of autophagy in CL regression and its association with apoptosis. Ovaries were obtained from pseudopregnant rats at Day 2 (early-), 7 (mid-), 14 and 20 (late-luteal stage) of the pseudopregnancy; autophagy-associated protein [microtuble-associated protein light chain 3 (LC3)] was immunolocalized and its expression level was measured. Luteal cell apoptosis was evaluated by measuring cleaved caspase 3 expression. LC3 expression increased slightly from early- to mid-luteal stage, with maximal levels detected at the late-luteal stage in steroidogenic luteal cells. The expression level of the membrane form of LC3 (LC3-II) also increased during luteal stage progression, and reached a maximum at the end point of late-luteal stage (Day 20). This pattern coincided with cleaved caspase 3 expression. Furthermore, LC3-II expression increased as did levels of cleaved caspase 3 in luteal cells cultured with prostaglandin F(2alpha) known to induce CL regression. These findings suggest that luteal cell autophagy is directly involved in CL regression and is correlated with increased apoptosis. In addition, autophagic processes were inhibited using 3-methyladenine or bafilomycine A1 to evaluate the role of autophagy in apoptosis induction. Inhibition of autophagosome degradation by fusion with lysosomes (bafilomycine A1) increased apoptosis and cell death. Furthermore, inhibition of autophagosome formation (3-methyladenine) decreased apoptosis and cell death, suggesting that the accumulation of autophagosomes induces luteal cell apoptosis. In conclusion, these results indicate that autophagy is involved in rat luteal cell death through apoptosis, and is most prominent during CL regression.
Expression regulated by
LH, Growth Factors/ cytokines, mTOR
Comment
AKT is involved in granulosa cell autophagy regulation via mTOR signaling during rat follicular development and atresia. Choi J 2013 et al.
In this study we examined whether granulosa cell autophagy during follicular development and atresia was regulated by the class I phosphoinositide-3 kinase (PI3K)/protein kinase B (AKT) pathway which is known to control activity of mammalian target of rapamycin (mTOR), a major negative regulator of autophagy. Ovaries and granulosa cells were obtained using an established gonadotropin-primed immature rat model that induces follicular development and atresia. Autophagy was evaluated by measuring the expression level of microtubule-associated protein light chain 3-II (LC3-II) using Western blots and immunohistochemistry. The activity of AKT and mTOR were also examined by observing the phosphorylation of AKT and ribosomal protein S6 kinase (S6K), respectively. After gonadotropin injection, LC3-II expression was suppressed and phosphorylation of AKT and S6K increased in rat granulosa cells. In contrast, gonadotropin withdrawal by metabolic clearance promoted LC3-II expression and decreased phosphorylation of AKT and S6K. In addition, in-vitro FSH treatment of rat granulosa cells also indicated inhibition of LC3-II expression accompanied by a marked increase in phosphorylation of AKT and S6K. Inhibition of AKT phosphorylation using AKT inhibitor VIII suppressed FSH-mediated phosphorylation of S6K, followed by an increase in LC3-II expression. Furthermore, co-treatment with FSH and AKT inhibitor increased the levels of apoptosis and cell death of granulosa cells compared to the single treatment with FSH. Taken together, our findings indicated that AKT-mediated activation of mTOR suppresses granulosa cell autophagy during follicular development and is involved in the regulation of apoptotic cell death.
/////////////////////////
Ovarian localization
Oocyte, Granulosa
Comment
Autophagy is activated in the ovarian tissue of polycystic ovary syndrome. Li D et al. (2017) The importance of autophagy in polycystic ovary syndrome (PCOS)-related metabolic disorders is increasingly being recognized, but few studies have investigated the role of autophagy in PCOS. Here, transmission electron microscopy demonstrated that autophagy was enhanced in the ovarian tissue from both humans and rats with PCOS. Consistent with this, ovarian granulosa cells from PCOS rats showed increases in the autophagy marker protein light chain 3B (LC3B), whereas levels of the autophagy substrate SQSTM1/p62 were decreased. In addition, the ratio of LC3-II/LC3-I was markedly elevated in human PCOS ovarian tissue compared with normal ovarian tissue. Real-time PCR arrays indicated that 7 and 34 autophagy-related genes were down- and upregulated in human PCOS ovarian tissue, respectively. STRING, Signal-Net, and regression analysis suggested that there is a wide range of interactions among these 41 genes, and a potential network based on EGFR, ERBB2, FOXO1, MAPK1, NFKB1, IGF1, TP53, and MAPK9 may be responsible for autophagy activation in PCOS. Systematic functional analysis of 41 differential autophagy-related genes indicated that these genes are highly involved in specific cellular processes such as response to stress and stimulus, and are linked to four significant pathways, including the insulin, ERBB, and mTOR signalling pathways, and protein processing in the endoplasmic reticulum. This study provides evidence for a potential role of autophagy disorders in PCOS, in which autophagy may be an important molecular event in the pathogenesis of PCOS.//////////////////
The role of autophagy in follicular development and atresia in rat granulosa cells. Choi JY et al. OBJECTIVE: To investigate the involvement of autophagy in folliculogenesis and its correlation with apoptosis. DESIGN: Animal model-based study. SETTING: University medical center. ANIMAL(S): 21-day-old female Sprague-Dawley rats. INTERVENTION(S): Ovaries obtained from established immature rat models primed with pregnant mare serum gonadotropin (PMSG) were used for the induction of follicular development and atresia. Granulosa cells isolated from developing follicles were cultured in serum-free condition with or without follicle-stimulating hormone. MAIN OUTCOME MEASURE(S): Microtubule-associated light-chain protein 3 (LC3) and autophagic vacuoles were used as autophagic markers, and cleaved caspase-3 was used as an apoptotic marker in ovaries and/or granulosa cells. RESULT(S): The LC3 protein was expressed mainly in granulosa cells during all developmental stages. In granulosa cells isolated from PMSG-primed immature rat ovaries, LC3-II expression showed a similar expression pattern to cleaved caspase-3. In addition, granulosa cells of atretic follicles that showed intense cleaved caspase-3 staining also showed intense LC3 immunoreactivity. An in vitro culture experiment revealed that the levels of LC3-II and cleaved caspase-3 proteins were gonadotropin-dependent. The induction and the gonadotropin dependency of granulosa cell autophagy were confirmed by the observation of autophagic vacuoles under transmission electron microscopy. CONCLUSION(S): These preliminary results suggest that autophagy is induced mainly in granulosa cells during folliculogenesis and shows good correlation with apoptosis.
Analysis of different cell death processes of prepubertal rat oocytes in vitro. Escobar ML et al. The processes of cell death were studied in vitro in populations of oocytes isolated from prepubertal rats. In order to identify apoptosis, the externalized phosphatidylserine was recognized with Annexin-V coupled to FITC and the fragmentation of DNA was demonstrated by means of electrophoresis. Oocytes were tested for autophagy by means of the incorporation of monodansylcadaverine and monitoring Lc3-I/Lc3-II by western blot. The expression of mRNA marker genes of autophagy and of apoptosis was studied by means of RT-PCR in pure populations of oocytes. Some oocytes expressed at least one of the following markers: caspase-3, lamp1 and Lc3. Some oocytes were positive to Annexin-V or to monodansylcadaverine. However, most of them were simultaneously positive to both markers. The relative frequency of oocytes simultaneously positive to markers of apoptosis and autophagy did not change in the different ages studied. The transformation of Lc3-I in Lc3-II was present in all populations of oocytes studied. The mRNAs for caspase-3, lamp1 and Lc3 were present in all populations of oocytes analyzed. Our results demonstrate that oocytes of rats from new born to prepubertal age are eliminated by means of three different cell death processes: apoptosis, autophagy and a mixed event in which both routes to cell death participate in the same cell.
Follicle stages
Comment
Molecular cloning and expression analyses of porcine MAP1LC3A in the granulosa cells of normal and miniature pig. Kim SH et al. ABSTRACT: BACKGROUND: The members of the microtubule-associated protein 1 light chain (MAP1LC) family, especially those of the LC3 family (MAP1LC3A, B, C), are known to induce autophagy upon localization onto the autophagosomal membrane. In this regard, LC3 can be utilized as a marker for the formation of autophagosomes during the process of autophagy. The aims of this study are to clone porcine MAP1LC3A, and analyze the pattern of its expression in the ovarian tissues of normal and miniature pig ovary in an attempt to understand the distinct mode of apoptosis between two strains. METHODS: Rapid amplification of cDNA ends (RACE) were used to obtain the 5[prime] and 3[prime] ends of the porcine MAP1LC3A full length cDNA. Reverse-transcriptase-PCR (RT-PCR), real-time PCR, and western blot analysis were performed to examine the expression of porcine MAP1LC3A. The localization of MAP1LC3A in the ovary was determined by In situ Hybridization and Immunohistochemical staining. RESULTS: We cloned the full-length cDNA of porcine MAP1LC3A and identified an open reading frame of 980 bp encoding 121 amino acids. Based on its homology to known mammalian proteins (98%) this novel cDNA was designated as porcine MAP1LC3A and registered to the GenBank (Accession No. GU272221). We compared the expression of MAP1LC3A in the Graafian follicles of normal and miniature pigs by in situ hybridization at day 15 of the estrus cycle. While normal pigs showed a stronger expression of MAP1LC3A mRNA than miniature pigs in the theca cell area, the expression was lower in the granulosa cells. Immunofluorescence analysis of the MAP1LC3A fusion reporter protein showed the subcellular localization of porcine MAP1LC3A and ATG5 as a punctate pattern in the cytoplasm of porcine granulosa cells under stress conditions. In addition, the expressions of MAP1LC3A and ATG5 were higher in normal pigs than in miniature pigs both in the presence and absence of rapamycin. CONCLUSIONS: The newly cloned porcine MAP1LC3A provides a novel autophagosomal marker in both normal and miniature pig. We demonstrated that the expression of MAP1LC3A in graafian follicle is distinct in normal and miniature pig, which may explain the unique folliculogenesis of miniature pigs.
Phenotypes
Mutations
1 mutations
Species: C. elegans
Mutation name: None
type: null mutation fertility: infertile - ovarian defect Comment: Degradation of Paternal Mitochondria by Fertilization-Triggered Autophagy in C. elegans Embryos. Sato M et al. The mitochondrial genome is believed to be maternally inherited in many eukaryotes. Sperm-derived paternal mitochondria enter the oocyte cytoplasm upon fertilization and then normally disappear during early embryogenesis. However, the mechanism responsible for this clearance has been unknown. Here, we show that autophagy, which delivers cytosolic components to lysosomes for degradation, is required for the elimination of paternal mitochondria in Caenorhabditis elegans. Immediately after fertilization, sperm-derived components trigger the localized induction of autophagy around sperm mitochondria. Autophagosomes engulf paternal mitochondria, resulting in their lysosomal degradation during early embryogenesis. In autophagy-defective zygotes, paternal mitochondria and their genome remain even in the first larval stage. Thus, fertilization-triggered autophagy is required for selective degradation of paternal mitochondria and thereby maternal inheritance of mitochondrial DNA.