Long-Term Ex Vivo Expansion of Murine Spermatogonial Stem Cells in a Simple Serum-Free Medium.

Spermatogonial stem cells (SSCs) possess both self-renewal and differentiation abilities to sustain lifelong production of enormous numbers of spermatozoa in males. SSCs hold a unique position among tissue-specific stem cells in adults because of their ability to transmit the genetic information to subsequent generations. Ex vivo expansion of SSCs in conjunction with their transplantation is highly invaluable to study SSCs and develop new reproductive technologies for therapeutic applications.

Conserved and non-conserved characteristics of porcine glial cell line-derived neurotrophic factor expressed in the testis.

Glial cell line-derived neurotrophic factor (GDNF) is essential for the self-renewal and proliferation of spermatogonial stem cells (SSCs) in mice, rats, and rabbits. Although the key extrinsic factors essential for spermatogonial proliferation in other mammals have not been determined, GDNF is one of the potential candidates. In this study, we isolated porcine GDNF (pGDNF) cDNAs from neonatal testis and generated recombinant pGDNF to investigate its biological activity on gonocytes/undifferentiated spermatogonia, including SSCs.

Cell-surface DEAD-box polypeptide 4-immunoreactive cells and gonocytes are two distinct populations in postnatal porcine testes.

DEAD-box polypeptide 4 (DDX4) is an evolutionally conserved ATP-dependent RNA helicase that is exclusively expressed in germ cell lineage. Although DDX4 is believed to reside and function in the cytoplasm, recent studies in mice and humans suggest that its epitope is expressed on the cell surface of a small subpopulation in the ovary, putative oogonial stem cells. No study has examined whether such cell-surface DDX4(+) cells exist in the testes of any species.

Proteomic analysis of in vivo 14-3-3 interactions in the yeast Saccharomyces cerevisiae.

The yeast Saccharomyces cerevisiae produces two 14-3-3 proteins, Bmh1 and Bmh2, whose exact functions have remained unclear. Here, we performed a comprehensive proteomic analysis using multistep immunoaffinity purification and mass spectrometry and identified 271 yeast proteins that specifically bind to Bmh1 and -2 in a phosphorylation-dependent manner. The identified proteins have diverse biochemical functions and cellular roles, including cell signaling, metabolism, and cell cycle regulation.

14-3-3 proteins modulate the expression of epithelial Na+ channels by phosphorylation-dependent interaction with Nedd4-2 ubiquitin ligase.

The ubiquitin E3 protein ligase Nedd4-2 is a physiological regulator of the epithelial sodium channel ENaC, which is essential for transepithelial Na+ transport and is linked to Liddle's syndrome, an autosomal dominant disorder of human salt-sensitive hypertension. Nedd4-2 function is negatively regulated by phosphorylation via a serum- and glucocorticoid-inducible protein kinase (Sgk1), which serves as a mechanism to inhibit the ubiquitination-dependent degradation of ENaC. We report here that 14-3-3 proteins participate in this regulatory process through a direct interaction with a phosphorylated form of human Nedd4-2 (a human gene product of KIAA0439, termed hNedd4-2).

Transcriptomic and proteomic analysis of a 14-3-3 gene-deficient yeast.

BMH1 and BMH2 encode Saccharomyces cerevisiae 14-3-3 homologues whose exact functions have remained unclear. The present work compares the transcriptomic and proteomic profiles of the wild type and a BMH1/2-deficient S. cerevisiae mutant (bmhDelta) using DNA microarrays and two-dimensional polyacrylamide gel electrophoresis.