Differential expression of a gene homologous to a G-alpha protein gene in neonatal mouse skin during development of hair follicles

Overexpression of GαS in Murine Osteoblasts In Vivo Leads to Increased Bone Mass and Decreased Bone Quality

Gα_S is a heterotrimeric G protein that transduces signals from activated G protein-coupled receptors on the cell surface to stimulate adenylyl cyclase/cyclic adenosine monophosphate (AMP) signaling. Gα_S plays a central role in mediating numerous growth and maintenance processes including osteogenesis and bone turnover. Decreased Gα_S expression or activating mutations in Gα_S both affect bone, suggesting that modulating Gα_S protein levels may be important for bone health and development. To examine the effects of increased osteoblastic Gα_S expression on bone development in vivo, we generated transgenic mice with Gα_S overexpression in osteoblasts (HOM-Gs mice) driven by the 3.6-kilobase (kb) Col1A1 promoter. Both male and female HOM-Gs mice exhibit increased bone turnover with overactive osteoblasts and osteoclasts, resulting in a high bone mass phenotype with significantly reduced bone quality. At 9 weeks of age, HOM-Gs mice have increased trabecular number, volumetric BMD (vBMD), and bone volume; however, the bone was woven and disorganized. There was also increased cortical bone volume despite an overall reduction in size in HOM-Gs mice along with increased cortical porosity and brittleness. The skeletal phenotype of HOM-Gs mice progressed into maturity at 26 weeks of age with further accrual of trabecular bone, whereas WT mice lost trabecular bone at this age. Although cortical bone volume and geometry were similar between mature HOM-Gs and WT mice, increased porosity persisted and the bone was weaker. At the cellular level, these alterations were mediated by an increase in bone resorption by osteoclasts and an overwhelmingly higher increase in bone formation by osteoblasts. In summary, our findings demonstrate that high osteoblastic Gα_S expression results in aberrant skeletal development in which bone production is favored at the cost of bone quality. © 2017 American Society for Bone and Mineral Research.

Action Mechanism of Chamaecyparis obtusa Oil on Hair Growth

This study was carried out to examine the action mechanism of Chamaecyparis obtusa oil (CO) on hair growth in C57BL/6 mice. For alkaline phosphatase (ALP) and γ-glutamyl transpeptidase (γ-GT) activities in the skin tissue, at week 4, the 3% minoxidil (MXD) and 3% CO treatment groups showed an ALP activity that was significantly higher by 85% (p < 0.001) and 48% (p < 0.05) and an γ-GT activity that was significantly higher by 294% (p < 0.01) and 254% (p < 0.05) respectively, as compared to the saline (SA) treatment group. For insulin-like growth factor-1 (IGF-1) mRNA expression in the skin tissue, at week 4, the MXD and CO groups showed a significantly higher expression by 204% (p < 0.05) and 426% (p < 0.01) respectively, as compared to the SA group. At week 4, vascular endothelial growth factor (VEGF) expression in the MXD and CO groups showed a significantly higher expression by 74% and 96% (p < 0.05) respectively, however, epidermal growth factor (EGF) expression in the MXD and CO groups showed a significantly lower expression by 66% and 61% (p < 0.05) respectively, as compared to the SA group. Stem cell factor (SCF) expression in the MXD and CO groups was observed by immunohistochemistry as significant in a part of the bulge around the hair follicle and in a part of the basal layer of the epidermis. Taking all the results together, on the basis of effects on ALP and γ-GT activity, and the expression of IGF-1, VEGF and SCF, which are related to the promotion of hair growth, it can be concluded that CO induced a proliferation and division of hair follicle cells and maintained the anagen phase. Because EGF expression was decreased significantly, CO could delay the transition to the catagen phase.

A novel gene homologous to teashirt is differentially expressed in neonatal mouse skin during development of hair follicles

Neonatal mouse skin is useful for studying changes in gene expression during development of hair follicles, as the mitotic activity of skin cells changes shortly after birth. Using ribonucleic acid (RNA) differential display, a 261-nt message has been identified in the skin, specifically on d 3-5 but not on d 2 after birth. Confirmation of its expression by ribonuclease protection assay showed that stronger expression is seen on d 3-5 compared with d 1-2. Using RNA ligase-mediated rapid amplification of 5' complementary deoxyribonucleic acid ends, we have successfully isolated a 3046-bp gene, which has 93% sequence homology to a mouse teashirt1 gene. Amino acid analysis showed that it has 74% identity to the mouse teashirt1 protein and possesses zinc-finger motifs 1, 2, and 3. In situ hybridization data revealed that it is mainly expressed in the follicle bulb, including dermal papilla and matrix cells. As the proliferation of bulb cells is important to follicle development during this period, the finding of its strong expression on d 3-5 suggests that the identified gene is a potential candidate for follicle growth.

Mouse keratinocytes express c98, a novel gene homologous to bcl-2, that is stimulated by insulin-like growth factor 1 and prevents dexamethasone-induced apoptosis

Many studies have been undertaken to investigate the mechanisms of skin differentiation. In particular, growth factors and hormones are believed to play important roles in skin proliferation, differentiation and survival. Insulin-like growth factor-1 (IGF-1) has been identified as a survival factor in many tissues including the skin, but the molecular mechanism of IGF-1 in epidermal differentiation is not completely understood. Neonatal mouse skin is useful for studying changes in gene expression, as the mitotic activity of skin cells changes shortly after birth. Using RNA differential display (DD), a 357-nt message that is specifically expressed in the epidermal keratinocytes of IGF-1-injected newborn mice but not in controls, has been identified. Confirmation of expression of this gene by ribonuclease protection assay (RPA) showed that its mRNA expression in the epidermal keratinocytes is induced by IGF-1. Using RNA ligase-mediated rapid amplification of 5' cDNA ends (RLM-5'-RACE), we have successfully isolated a 3473-bp full-length gene, c98, that has 97% sequence homology to a bcl-2-like gene, bcl-w. The latter has been identified as a proto-oncogene in several murine myeloid cell lines. Amino acid sequence analysis of the c98 showed that it has 97% sequence identity to the bcl-w protein and possesses bcl-2 homology domains (BH) 1, 2 and 3. Immunoblotting data revealed similar increases of c98 protein expression to its mRNA expression in the keratinocytes of IGF-1-injected animals. Weak expression of other bcl-2 family member proteins, bax, bcl-2 and bcl-xL, were also found in the immunoblots. Additionally, IGF-1 was found to be able to protect epidermal keratinocytes from dexamethasone (DEX)-induced apoptosis, based on the findings that after the cells were treated with DEX, DNA laddering was present in the control mice but not in those injected with IGF-1. Further, using a photometric enzyme-linked immunoassay to quantitate keratinocyte death, we found that after addition of DEX, the amounts of cytoplasmic histone-associated DNA fragments were not significantly (P>0.05) different in IGF-1-treated cells compared with untreated control cells during the high mitotic stage of skin epidermis. To assess the role of c98 in these anti-apoptotic processes, we have generated a recombinant plasmid that contains an expression vector and c98 and transfected this plasmid into the keratinocytes from mice without IGF-1-treatment. Expression of the c98 protein was found to completely (P>0.05) block DEX-induced apoptosis after cell transfection. Taken together, our current data demonstrated that IGF-1 plays an anti-apoptotic role in the DEX-induced apoptosis in epidermal keratinocytes and this, at least in part, may be mediated through expression of c98.