Abstract
Cell differentiation during spermatogenesis requires a proper actin dynamic, regulated by several proteins, including formins. Disheveled-Associated-Activator of Morphogenesis1 (DAAM1) belongs to the formins and promotes actin polymerization. Our results showed that oral D-Aspartate (D-Asp) administration, an excitatory amino acid, increased DAAM1 protein levels in germ cells cytoplasm of rat testis. Interestingly, after the treatment, DAAM1 also localized in rat spermatogonia (SPG) and mouse GC-1 cells nuclei. We provided bioinformatic evidence that DAAM1 sequence has two predicted NLS, supporting its nuclear localization. The data also suggested a role of D-Asp in promoting DAAM1 shuttling to the nuclear compartment of those proliferative cells. In addition, the proliferative action induced by D-Asp is confirmed by the increased levels of PCNA, a protein expressed in the nucleus of cells in the S phase and p-H3, a histone crucial for chromatin condensation during mitosis and meiosis. In conclusion, we demonstrated, for the first time, an increased DAAM1 protein levels following D-Asp treatment in rat testis and also its localization in the nucleus of rat SPG and in mouse GC-1 cells. Our results suggest an assumed role for this formin as a regulator of actin dynamics in both cytoplasm and nuclei of the germ cells.
Highlights
In mammals, spermatogenesis is a highly complex and coordinated process leading to the formation of the mature gametes, the spermatozoa, able to pass through female genital tract and fertilize the oocyte
We recently demonstrated that D-Asp increased the expression of the enzyme Prolyl Endopeptidase (PREP) in the rat testis [35], a serine protease having a pivotal role in the regulation of mammalian steroidogenesis and spermatogenesis [36,37,38]
Densitometric analysis of Disheveled-Associated-Activator of Morphogenesis1 (DAAM1) immunofluorescence was performed with ImageJ Software counting 30 seminiferous tubules/animal for a total of 150 tubules per group
Summary
Spermatogenesis is a highly complex and coordinated process leading to the formation of the mature gametes, the spermatozoa, able to pass through female genital tract and fertilize the oocyte. It is well known that in the Leydig cells the amino acid modulates steroidogenesis by eliciting the adenylate cyclase-cAMP and mitogen-activated protein kinase (MAPK) pathways [11,19,35], while in SPG, D-Asp may directly activate proliferation through both MAPK and AKT pathways [29,35]. This current knowledge does not exclude that D-Asp may regulate, activating and/or inhibiting, other molecular pathways. To better understand the underlying molecular pathways responsible for the action of D-Asp in the rat testis, here, we examined the effects of oral administration of D-Asp on DAAM1 protein levels and localization in adult rats
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