title: Mullerian inhibiting substance recruits ALK3 to regulate Leydig cell differentiation.
abstract: Müllerian inhibiting substance (MIS) not only induces Müllerian duct regression during male sexual differentiation but also modulates Leydig cell steroidogenic capacity and differentiation. MIS actions are mediated through a complex of homologous receptors: a type II ligand-binding receptor [MIS type II receptor (MISRII)] and a tissue-specific type I receptor that initiates downstream signaling. The putative MIS type I receptors responsible for Müllerian duct regression are activin A type II receptor, type I [Acvr1/activin receptor-like kinase 2 (ALK2)], ALK3, and ALK6, but the one recruited by MIS in Leydig cells is unknown. To identify whether ALK3 is the specific type I receptor partner for MISRII in Leydig cells, we generated Leydig cell-specific ALK3 conditional knockout mice using a Cre-lox system and compared gene expression and steroidogenic capacity in Leydig cells of ALK3(fx/fx)Cyp17(cre+) and control mice (ALK3(fx/fx)Cyp17(cre-) or ALK3(fx/wt)Cyp17(cre-) littermates). We found reduced mRNA expression of the genes encoding P450c17, StAR, and two enzymes (17βHSD-III and 3βHSD-VI) that are expressed in differentiated adult Leydig cells and increased expression of androgen-metabolizing enzymes (3α-HSD and SRD5A2) and proliferating cell nuclear antigen (PCNA) in Leydig cells of ALK3(fx/fx)Cyp17(cre+) mice. Despite down-regulation of steroidogenic capacity in ALK3(fx/fx)Cyp17(cre+) mice, the loss of MIS signaling also stimulates Leydig cell proliferation such that plasma testosterone and androstenedione concentrations are comparable to that of control mice. Collectively, these results indicate that the phenotype in ALK3 conditional knockout mice is similar to that of the MIS-knockout mice, confirming that ALK3 is the primary type I receptor recruited by the MIS-MISRII complex during Leydig cell differentiation.
authors.affiliation: Pediatric Endocrine Division, Departments of Pediatrics and Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA.
authors.forename: Xiufeng
authors.initials: X
authors.lastname: Wu
authors.forename: Ningning
authors.initials: N
authors.lastname: Zhang
authors.forename: Mary M
authors.initials: MM
authors.lastname: Lee
mesh_terms: D030201:Activin Receptors, Type I / Q000235:genetics / Q000378:metabolism; D000735:Androstenedione / Q000097:blood; D000818:Animals; D054304:Anti-Mullerian Hormone / Q000235:genetics / Q000378:metabolism*; D052005:Bone Morphogenetic Protein Receptors, Type I / Q000235:genetics / Q000378:metabolism*; D002452:Cell Count; D002454:Cell Differentiation / Q000502:physiology*; D015536:Down-Regulation / Q000502:physiology; D007985:Leydig Cells / Q000166:cytology / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D018000:Receptors, Peptide / Q000235:genetics / Q000378:metabolism*; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D013254:Steroid 17-alpha-Hydroxylase / Q000235:genetics / Q000378:metabolism; D013737:Testis / Q000378:metabolism; D013739:Testosterone / Q000097:blood; D000098682:Steroidogenic Acute Regulatory Protein
chemical_list: D010750:Phosphoproteins; D018000:Receptors, Peptide; D018125:Receptors, Transforming Growth Factor beta; C084621:anti-Mullerian hormone receptor; D000098682:Steroidogenic Acute Regulatory Protein; D013739:Testosterone; D000735:Androstenedione; D054304:Anti-Mullerian Hormone; D007986:Luteinizing Hormone; D013254:Steroid 17-alpha-Hydroxylase; D030201:Activin Receptors, Type I; C498943:Acvr1 protein, mouse; C498212:Bmpr1a protein, mouse; C498215:Bmpr1b protein, mouse; D052005:Bone Morphogenetic Protein Receptors, Type I