title: Expression and function of cannabinoid receptors CB1 and CB2 and their cognate cannabinoid ligands in murine embryonic stem cells.
abstract: BACKGROUND
  Characterization of intrinsic and extrinsic factors regulating the self-renewal/division and differentiation of stem cells is crucial in determining embryonic stem (ES) cell fate. ES cells differentiate into multiple hematopoietic lineages during embryoid body (EB) formation in vitro, which provides an experimental platform to define the molecular mechanisms controlling germ layer fate determination and tissue formation.
  
  
  RESULTS
  The cannabinoid receptor type 1 (CB1) and cannabinoid receptor type 2 (CB2) are members of the G-protein coupled receptor (GPCR) family, that are activated by endogenous ligands, the endocannabinoids. CB1 receptor expression is abundant in brain while CB2 receptors are mostly expressed in hematopoietic cells. However, the expression and the precise roles of CB1 and CB2 and their cognate ligands in ES cells are not known. We observed significant induction of CB1 and CB2 cannabinoid receptors during the hematopoietic differentiation of murine ES (mES)-derived embryoid bodies. Furthermore, mES cells as well as ES-derived embryoid bodies at days 7 and 14, expressed endocannabinoids, the ligands for both CB1 and CB2. The CB1 and CB2 antagonists (AM251 and AM630, respectively) induced mES cell death, strongly suggesting that endocannabinoids are involved in the survival of mES cells. Treatment of mES cells with the exogenous cannabinoid ligand Delta(9)-THC resulted in the increased hematopoietic differentiation of mES cells, while addition of AM251 or AM630 blocked embryoid body formation derived from the mES cells. In addition, cannabinoid agonists induced the chemotaxis of ES-derived embryoid bodies, which was specifically inhibited by the CB1 and CB2 antagonists.
  
  
  CONCLUSIONS
  This work has not been addressed previously and yields new information on the function of cannabinoid receptors, CB1 and CB2, as components of a novel pathway regulating murine ES cell differentiation. This study provides insights into cannabinoid system involvement in ES cell survival and hematopoietic differentiation.
authors.affiliation: Division of Experimental Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America.
authors.forename: Shuxian
authors.initials: S
authors.lastname: Jiang
authors.forename: Yigong
authors.initials: Y
authors.lastname: Fu
authors.forename: John
authors.initials: J
authors.lastname: Williams
authors.forename: Jodianne
authors.initials: J
authors.lastname: Wood
authors.forename: Lakshmipathi
authors.initials: L
authors.lastname: Pandarinathan
authors.forename: Shiri
authors.initials: S
authors.lastname: Avraham
authors.forename: Alexandros
authors.initials: A
authors.lastname: Makriyannis
authors.forename: Shalom
authors.initials: S
authors.lastname: Avraham
authors.forename: Hava Karsenty
authors.initials: HK
authors.lastname: Avraham
mesh_terms: D000818:Animals; D063385:Cannabinoid Receptor Modulators / Q000235:genetics / Q000494:pharmacology* / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects; D002633:Chemotaxis / Q000187:drug effects; D013759:Dronabinol / Q000494:pharmacology*; D047108:Embryonic Development / Q000235:genetics / Q000502:physiology; D053595:Embryonic Stem Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D005786:Gene Expression Regulation; D051379:Mice; D012333:RNA, Messenger / Q000235:genetics; D043884:Receptor, Cannabinoid, CB1 / Q000235:genetics* / Q000502:physiology; D043885:Receptor, Cannabinoid, CB2 / Q000235:genetics* / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation
chemical_list: D063385:Cannabinoid Receptor Modulators; D012333:RNA, Messenger; D043884:Receptor, Cannabinoid, CB1; D043885:Receptor, Cannabinoid, CB2; D013759:Dronabinol