Purification of GFRα1+ and GFRα1- Spermatogonial Stem Cells Reveals a Niche-Dependent Mechanism for Fate Determination

Stem Cell Reports. 2018 Feb 13;10(2):553-567. doi: 10.1016/j.stemcr.2017.12.009. Epub 2018 Jan 11.

Abstract

Undifferentiated spermatogonia comprise a pool of stem cells and progenitor cells that show heterogeneous expression of markers, including the cell surface receptor GFRα1. Technical challenges in isolation of GFRα1+ versus GFRα1- undifferentiated spermatogonia have precluded the comparative molecular characterization of these subpopulations and their functional evaluation as stem cells. Here, we develop a method to purify these subpopulations by fluorescence-activated cell sorting and show that GFRα1+ and GFRα1- undifferentiated spermatogonia both demonstrate elevated transplantation activity, while differing principally in receptor tyrosine kinase signaling and cell cycle. We identify the cell surface molecule melanocyte cell adhesion molecule (MCAM) as differentially expressed in these populations and show that antibodies to MCAM allow isolation of highly enriched populations of GFRα1+ and GFRα1- spermatogonia from adult, wild-type mice. In germ cell culture, GFRα1- cells upregulate MCAM expression in response to glial cell line-derived neurotrophic factor (GDNF)/fibroblast growth factor (FGF) stimulation. In transplanted hosts, GFRα1- spermatogonia yield GFRα1+ spermatogonia and restore spermatogenesis, albeit at lower rates than their GFRα1+ counterparts. Together, these data provide support for a model of a stem cell pool in which the GFRα1+ and GFRα1- cells are closely related but show key cell-intrinsic differences and can interconvert between the two states based, in part, on access to niche factors.

Keywords: FACS; RNA-seq; germ cells; germ line; niche; spermatogonial stem cells; stem cells; telomerase; transplantation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • CD146 Antigen / genetics
  • Cell Differentiation / genetics*
  • Cell Lineage / genetics
  • Fibroblast Growth Factors / genetics
  • Flow Cytometry
  • Glial Cell Line-Derived Neurotrophic Factor / genetics
  • Glial Cell Line-Derived Neurotrophic Factor / metabolism
  • Glial Cell Line-Derived Neurotrophic Factor Receptors / genetics*
  • Male
  • Mice
  • Signal Transduction / genetics
  • Spermatogenesis / genetics*
  • Spermatogonia / cytology*
  • Spermatogonia / growth & development
  • Stem Cell Niche / genetics
  • Stem Cells / cytology
  • Testis / cytology

Substances

  • CD146 Antigen
  • Gfra1 protein, mouse
  • Glial Cell Line-Derived Neurotrophic Factor
  • Glial Cell Line-Derived Neurotrophic Factor Receptors
  • Mcam protein, mouse
  • Fibroblast Growth Factors