Developmental patterns of mST3GalV mRNA expression in the mouse: in situ hybridization using DIG-labeled RNA probes

Roles of gangliosides in mouse embryogenesis and embryonic stem cell differentiation

Gangliosides have been suggested to play important roles in various functions such as adhesion, cell differentiation, growth control, and signaling. Mouse follicular development, ovulation, and luteinization during the estrous cycle are regulated by several hormones and cell-cell interactions. In addition, spermatogenesis in seminiferous tubules of adult testes is also regulated by several hormones, including follicle-stimulating hormone (FSH) and luteinizing hormone (LH) and cell-cell interactions. The regulation of these processes by hormones and cell-cell interactions provides evidence for the importance of surface membrane components, including gangliosides. During preimplantation embryo development, a mammalian embryo undergoes a series of cleavage divisions whereby a zygote is converted into a blastocyst that is sufficiently competent to be implanted in the ma ternal uterus and continue its development. Mouse embryonic stem (mES) cells are pluripotent cells derived from mouse embryo, specifically, from the inner cell mass of blastocysts. Differentiated neuronal cells are derived from mES cells through the formation of embryonic bodies (EBs). EBs recapitulate many aspects of lineage-specific differentiation and temporal and spatial gene expression patterns during early embryogenesis. Previous studies on ganglioside expression during mouse embryonic development (including during in vitro fertilization, ovulation, spermatogenesis, and embryogenesis) reported that gangliosides were expressed in both undifferentiated and differentiated (or differentiating) mES cells. In this review, we summarize some of the advances in our understanding of the functional roles of gangliosides during the stages of mouse embryonic development, including ovulation, spermatogenesis, and embryogenesis, focusing on undifferentiated and differentiated mES cells (neuronal cells).

Pathophysiological implication of ganglioside GM3 in early mouse embryonic development through apoptosis

Apoptosis may occur in early embryos where the execution of essential developmental events has failed, and gangliosides, sialic acid-conjugated glycosphingolipids, are proposed to regulate cell differentiation and growth. To evaluate the regulatory roles of ganglioside GM3 in early embryonic development, this study examined its expressional patterns in apoptotic cells during early embryonic development in mice. Pre-implanted embryos were obtained by in vitro fertilization, which were treated at the 4-cell stage with three the apoptosis inducers, actinomycin D, camptothecin and cycloheximide, for 15 h. All three inducers significantly increased the percentage of apoptotic cells, as measured using a TUNEL method, but remarkably reduced the total cell numbers. The numbers of morula and blastocyst stages were significantly decreased by treatment of the embryos with the three apoptosis inducers compared with the control, with a similar result also observed in the number of blastomeres. Staining of early embryos with Hoechst 33342 revealed a significant percentage of apoptotic nuclei. Prominent immunofluorescence microscopy revealed a significant difference in the ganglioside GM3 expression in apoptotic embryos compared with the control, and RT-PCR also demonstrated a dramatic increase in ganglioside GM3 synthase mRNA in the apoptotic embryos. These results suggest that ganglioside GM3 may be pathophysiologically implicated in the regulation of early embryonic development through an apoptotic mechanism.

Decreases of ganglioside GM3 in streptozotocin-induced diabetic glomeruli of rats

Ganglioside GM(3) (NeuAcalpha3Galbeta4Glcbeta1Cer) is known to regulate the proliferation of many cell types and to maintain the charge-selective filtration barrier of glomeruli. Based on these, this study examined whether altered expression of ganglioside GM(3) was pathologically related with glomerular hypertrophy and proteinuria occurring in diabetic human and rat kidneys. Diabetic rats were produced by intraperitoneal injection of streptozotocin (80 mg/kg, I.P.). At 15 days after the induction of diabetes, glomerular volume and fibrotic matrix were dramatically elevated, whereas glomerular sialic acid contents were significantly reduced compared with control. Based upon mobility on high-performance thin-layer chromatography (HPTLC) and reactivity to anti-GM(3) monoclonal antibody, normal glomeruli showed a complex ganglioside pattern that consisted of six different components of gangliosides, mainly GM(3), and diabetes caused a severe reduction of these gangliosides with apparent changes in the composition of major ganglioside GM(3). Semi-quantitative analysis by HPTLC showed that ganglioside GM(3) was reduced to 57% of control in diabetic glomeruli. A prominent immunofluorescence microscopy showed a dramatic disappearance of GM(3) expression in diabetic glomeruli. These results indicate that diabetic glomeruli can be characterized by decreases of glomerular sialic acid content and ganglioside GM(3) expression, which may cause loss of charge-selective filtration barrier in renal glomeruli. These changes may be account, at least in part, for the development of glomerular hypertrophy and proteinuria seen in the early stage of diabetic glomerulopathy.

Differential distribution of ganglioside GM3 in seminiferous tubule and epididymis of adult rats

Gangliosides are ubiquitous membrane components in mammalian cells and are suggested to play important roles in various functions such as cell-cell interaction, adhesion, cell differentiation, growth control and signaling. Among all ganglio-series gangliosides, GM3 has the simplest carbohydrate structure, and has been shown as a major ganglioside in male reproductive system. To study GM3 distribution in the seminiferous tubule and epididymis, frozen sections were stained with specific monoclonal antibody (MAb) against ganglioside GM3. In the seminiferous tubule of testis, pachytene spermatocytes and spermatids expressed ganglioside GM3, but not in spermatogonia and sertoli cells. Spermatogonia and sertoli cells near the basement membrane were negatively reacted to anti-GM3. In the epididymis, GM3 was expressed only in some interstitial cells. Taken together, these results suggest that the expression of ganglioside GM3 in rat seminiferous tubule and epididymis is spatio-temporally regulated during spermatogenesis.