The Parathyroid Hormone Second Receptor PTH2R and its Ligand Tuberoinfundibular Peptide of 39 Residues TIP39 Regulate Intracellular Calcium and Influence Keratinocyte Differentiation

Abstract

Genes related to the parathyroid hormone (PTH) influence cutaneous immune defense and development, but the full functions of the PTH family in cutaneous biology remain incompletely understood. In this study, we examined the expression and potential functions of the PTH second receptor (PTH2R) and its ligand, the tuberoinfundibular peptide of 39 residues (TIP39), in the skin. TIP39 and PTH2R mRNA and protein were detectable in both human and mouse skin, and in cultured keratinocytes and adipocytes. TIP39 was observed in the basal layer of human skin, whereas PTH2R was detected in the spinous to granular layer. The subcellular localization of TIP39 in keratinocytes changed during calcium-induced differentiation and shifted to colocalize with PTH2R at the membrane. The addition of recombinant TIP39 to normal human keratinocytes in culture induced an increase in intercellular calcium and triggered aspects of terminal differentiation including decreased keratin-14 and increased involucrin expression. Consistent with these observations, PTH2R−/− mice were observed to have increased epidermal thickness. In summary, identification of TIP39 and its receptor in the epidermis reveals an additional PTH family member that is expressed in the skin and may influence keratinocyte function.

Activation of Parathyroid Hormone 2 Receptor Induces Decorin Expression and Promotes Wound Repair

“…PTH2R, parathyroid hormone second receptor. calcium in keratinocytes (Sato et al, 2016). Keratinocyte migration is stimulated by increased intracellular calcium and the nuclear factor of activated T-cell proteins, a family of Ca 2+ -activated transcription factors (Brun et al, 2014; Fang et al, 1998; Jauliac et al, 2002; O’Connor et al, 2007).…”

“…Total RNA from mouse tissue samples and cultured keratinocytes was extracted, and cDNA was synthesized as previously described (Sato et al, 2016). TaqMan gene expression assays (Thermo Fisher Scientific) were used to analyze expressions of mouse decorin (gene symbol, Dcn ; assay ID, Mm00514535_m1), mouse adiponectin (gene symbol, Adipoq ; assay ID, Mm00456425_m1), mouse syn-decan1 (gene symbol, Sdc1 ; assay ID, Mm00448918_m1), mouse syndecan2 (gene symbol, Sdc2 ; assay ID, Mm04207492_m1), mouse syndecan4 (gene symbol, Sdc4 ; assay ID, Mm00488527_m1), mouse aggrecan (gene symbol, Acan ; assay ID, Mm00545794_m1), mouse agrin (gene symbol, Agrn ; assay ID, Mm01264855_m1), mouse glypican1 (gene symbol, Gpc1 ; assay ID, Mm01264855_m1), mouse glypican2 (gene symbol, Gpc2 ; assay ID, Mm00549650_m1), mouse perlecan (gene symbol, Hspg2 ; assay ID, Mm01181173_g1), and mouse β-glycan (gene symbol, Tgfbr3 ; assay ID, Mm00803538_m1), as described by the manufacturer’s instructions.…”

“…Samples were lysed in radio-immunoprecipitation assay buffer as previously described (Sato et al, 2016). Protein concentrations were measured by BCA protein assay kit (Thermo Fischer Scientific).…”

“…Sectioning was performed at University of California–San Diego Moores Histology Core (La Jolla, CA). The detailed immunostaining method has been described (Sato et al, 2016). Anti-pCREB, anti-perilipin, anti-decorin, and Alexa Fluor 488- or 594-conjugated donkey IgG (Thermo Fisher Scientific) were used at 1μg/ml.…”

“…PTH, another PTH2R agonist, phosphorylates CREB (Atfi and Baron, 2010; Qiu et al, 2010), and phosphorylation of CREB induces decorin transcription (Akhurst, 2006; Wahab et al, 2000). Previously, we reported that TIP39 is expressed in both the epidermis and differentiated subcutaneous adipocytes and that it regulates intracellular calcium and affects keratinocyte differentiation (Sato et al, 2016). Furthermore, TIP39 up-regulates expression of the FN1, MMP13, and COL1A2 genes in PTH2R-overexpressing chondrocytes (Panda et al, 2009).…”