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Christophe Furman - One of the best experts on this subject based on the ideXlab platform.
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perilipin a potential substitute for Adipophilin in triglyceride storage in human macrophages
Atherosclerosis, 2006Co-Authors: G Larigauderie, Christophe Furman, Michael Jaye, Jeancharles Fruchart, Mohamed Amine Bouhlel, Mustapha RouisAbstract:Abnormal lipid deposition in human arteries leads to the formation of fatty streaks due to the accumulation of a large number of macrophage derived-foam cells. The formation and catabolism of intracellular lipid droplets is regulated by droplet-associated proteins. Among such proteins, the role of perilipin in human macrophages was unknown. In this study, we first showed that perilipin expression was increased during differentiation of human monocytes to macrophages. Interestingly, cellular perilipin content was unaffected by treatment of cells with OxLDL, AcLDL, VLDL or sterol esters. Moreover, its expression was not dependent on the presence of Adipophilin, another lipid droplet-associated protein, since it was not affected by transfection of macrophages with siRNA-Adipophilin. Perilipin overexpression in macrophages with an expression vector resulted in significant lipid droplet formation and TG accumulation and this was unaffected by decreasing Adipophilin levels using siRNA. Consequently, perilipin, like Adipophilin, might play an important role in the conversion of macrophages into foam cells and contribute to lesion formation. Therefore, inhibition of Adipophilin might not be sufficient to prevent lesion formation as previously suggested, and perilipin inhibition might be additionally required.
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Adipophilin increases triglyceride storage in human macrophages by stimulation of biosynthesis and inhibition of β oxidation
FEBS Journal, 2006Co-Authors: G Larigauderie, Clarisse Cuazperolin, Amena Ben Younes, Christophe FurmanAbstract:Lipid accumulation alters macrophage biology and contributes to lipid retention within the vessel wall. In this study, we investigated the role of Adipophilin on triglyceride accumulation and lipid-droplet formation in THP-1-derived macrophages (THP-1 macrophages). In the presence of acetylated low-density lipoprotein, macrophages infected with an adenovirus expressing human Adipophilin showed a 31% increase in triglyceride content and a greater number of lipid droplets compared with control cells. Incubation of macrophages with very low-density lipoprotein (VLDL) dramatically increased cellular triglyceride content similarly in control and Adipophilin-overexpressing cells. By itself, VLDL increased Adipophilin expression, which explains the lack of effect of Adipophilin overexpression on cellular triglyceride content in macrophages loaded with VLDL. The lipid-droplet content of macrophages was increased by overexpression of Adipophilin and/or loading with VLDL. In contrast, inhibition of Adipophilin expression using siRNA prevented lipid-droplet formation and significantly reduced intracellular triglyceride content. Using inhibitors of β-oxidation and acyl-coenzyme A synthetase, results were obtained which suggest that Adipophilin elevates cellular lipids by inhibition of β-oxidation and stimulation of long-chain fatty acid incorporation into triglycerides. Adipophilin expression in THP-1 macrophages altered the cellular content of different lipids and enhanced the size of lipid droplets, consistent with a role for Adipophilin in human foam cell formation.
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Adipophilin enhances lipid accumulation and prevents lipid efflux from thp 1 macrophages potential role in atherogenesis
Arteriosclerosis Thrombosis and Vascular Biology, 2004Co-Authors: G Larigauderie, Christophe Furman, Michael Jaye, C Lasselin, Corinne Copin, Jeancharles Fruchart, Graciela Castro, Mustapha RouisAbstract:Objective— Uptake of modified low-density lipoprotein (LDL) by macrophages through scavenger receptors results in lipid droplets accumulation and foam cell formation. Excess lipid deposition in macrophages has been reported to modulate expression of several genes including Adipophilin. In this study, we investigated the function of Adipophilin in lipid accumulation and cholesterol efflux in THP-1 macrophages. Methods and Results— Adipophilin mRNA expression was 3.5-fold higher in human atherosclerotic plaques compared with healthy areas of the same arteries. Moreover, in the presence of acetylated LDL (AcLDL), triglycerides and cholesteryl esters were increased in macrophages overexpressing Adipophilin by 40% and 67%, respectively, whereas their accumulation was reduced when endogenous cellular Adipophilin was depleted using siRNA approach. In addition, neither overexpression nor downregulation of Adipophilin altered expression of genes involved in lipid efflux. However, the affinity and the number of AcLDL receptors were not affected. After 24-hour incubation of lipid-loaded macrophages with apolipoprotein A-I, cholesterol efflux was reduced by 47% in Adipophilin transfected cells versus control cells. Conclusion— Our results showed that stimulation of Adipophilin expression in macrophages by modified LDL promotes triglycerides and cholesterol storage and reduces cholesterol efflux. Therefore, Adipophilin might contribute, in vivo, to lipid accumulation in the intima of the arterial wall.
Mitsuaki Ishida - One of the best experts on this subject based on the ideXlab platform.
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Adipophilin expression is an independent marker for poor prognosis of patients with triple negative breast cancer an immunohistochemical study
PLOS ONE, 2020Co-Authors: Katsuhiro Yoshikawa, Mitsuaki Ishida, Hirotsugu Yanai, Koji Tsuta, Mitsugu Sekimoto, Tomoharu SugieAbstract:Adipophilin is a lipid droplet-associated protein whose expression can act as a prognostic marker for specific cancers. Using immunohistochemical staining and tissue microarrays, we assayed the expression of Adipophilin in 61 patients with triple-negative breast cancer (TNBC) who underwent surgery from January 2006-December 2018. Relapse-free survival (RFS) and its risk factors were analyzed based on Adipophilin expression. Fourteen (23.0%) patients expressed Adipophilin. As compared to the Adipophilin-negative TNBC patients, Adipophilin-positive patients exhibited poor RFS (p = 0.032). Among the TNBC patients with a high Ki-67 labeling index, patients negative for Adipophilin exhibited better RFS than patients positive for Adipophilin (p = 0.032). Moreover, among patients who did not undergo adjuvant chemotherapy, patients negative for Adipophilin expression exhibited better RFS than Adipophilin-positive patients (p = 0.080). Multivariate analysis showed that Adipophilin expression correlated with a high rate of relapse (hazard ratio, 4.89; 95% confidence interval, 1.04-23.0; p = 0.044). Taken together, these results indicate that Adipophilin is a novel marker for the poor prognosis of patients with TNBC.
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Adipophilin expression as an independent marker for poor prognosis of patients with triple negative breast cancer
Journal of Clinical Oncology, 2020Co-Authors: Katsuhiro Yoshikawa, Mitsuaki Ishida, Hirotsugu Yanai, Koji Tsuta, Mitsugu Sekimoto, Tomoharu SugieAbstract:e12552Background: Adipophilin (ADP) is a lipid-regulating protein of the perilipin/Adipophilin/tail interacting protein of 47 kDa (PAT) family that coats the surfaces of cytoplasmic lipid droplets....
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Adipophilin expression is an indicator of poor prognosis in patients with pancreatic ductal adenocarcinoma an immunohistochemical analysis
Pancreatology, 2019Co-Authors: Yuki Hashimoto, Mitsuaki Ishida, Hironori Ryota, Tomohisa Yamamoto, Hisashi Kosaka, Satoshi Hirooka, So Yamaki, Masaya Kotsuka, Yoichi Matsui, Hiroaki YanagimotoAbstract:Abstract Objective Adipophilin is a lipid droplet-associated protein, and its expression has been correlated with aggressive clinical behavior in some types of carcinomas, though its role in pancreatic ductal adenocarcinoma (PDAC) has not been clarified. This study aimed to evaluate the role of Adipophilin in PDAC. Methods By immunohistochemical staining using tissue microarrays, we analyzed the expression profiles of Adipophilin in 181 consecutive PDAC patients who underwent macroscopic margin-negative resection from January 2008 to December 2015. Overall survival (OS) and recurrence-free survival (RFS) were compared based on Adipophilin expression, and the risk factors for OS, RFS, and early recurrence (within 6 months) were analyzed. Results Of the 181 evaluated patients, 51 (28.2%) were positive for Adipophilin expression. A histopathological grade of 3 (p = 0.0012), higher CA19-9 level (p = 0.0016), and R1 status (p = 0.028) were significantly associated with Adipophilin-positive patients who had significantly poor OS and RFS compared to those associated with Adipophilin-negative patients (p = 0.0007 and p = 0.0022, respectively). They also showed a significantly higher incidence of early recurrence (p = 0.030), based on multivariate analyses. Conclusions Adipophilin is a potential independent prognostic marker for PDAC.
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sebaceous carcinoma associated with bowen s disease a case report with emphasis on the pathogenesis of sebaceous carcinoma
International Journal of Clinical and Experimental Pathology, 2013Co-Authors: Mitsuaki Ishida, Muneo Iwai, Akiko Kagotani, Keiko Yoshida, Hidetoshi OkabeAbstract:Extraocular sebaceous carcinoma is a relatively rare skin appendage carcinoma [1]. Although ocular sebaceous carcinoma is thought to arise from the Meibomian glands and glands of Zeis, there is no evidence that extraocular sebaceous carcinoma arises from pre-existing sebaceous glands [2]. Most sebaceous carcinomas are invasive [1], however, only a few cases of sebaceous carcinoma associated with intraepidermal squamous neoplasia (actinic keratosis or Bowen’s disease) have been reported [3-8]. These cases suggest that extraocular sebaceous carcinoma can originate from pre-existing intraepidermal squamous neoplasia [8]. Herein, we report an additional case of sebaceous carcinoma associated with Bowen’s disease and discuss the pathogenesis of sebaceous carcinoma. A 67-year-old Japanese female presented with a left buttock tumor, which had been first detected approximately 1 year earlier, and had recently gradually enlarged. Physical examination revealed a relatively well-circumscribed skin-colored tumor with hyperkeratosis, measuring 43 x 38 mm in diameter, in her left buttock. The biopsy specimen revealed Bowen’s disease (squamous cell carcinoma in situ), and subsequently, total resection of the tumor was performed. Histopathological study of the resected specimen revealed proliferation of atypical squamous cells in the entire layer of the acanthotic epidermis accompanied by hyperparakeratosis (Figure 1A). These atypical squamous cells had enlarged and hyperchromatic nuclei (Figure 1B), and multinucleated atypical squamous cells were also present. Mitotic figures were scattered and present in the upper portion of the epidermis. Atypical mitotic figures were also observed (Figure 1B). No invasive neoplastic growth was noted (Figure 1A). Approximately 95% of the lesion was composed of the above-mentioned Bowen’s disease (squamous cell carcinoma in situ), and superficial sebaceous carcinoma was present in the central area of the lesion. This latter component was composed of proliferation of nests of atypical cells with vacuolated clear cytoplasm and large nuclei containing conspicuous nucleoli (Figure 1C, ,1D).1D). Sebaceous carcinoma had invaded into the superficial reticular dermis (Figure 1C). Moreover, atypical cells containing vacuolated cytoplasm were present within the lesion of Bowen’s disease adjacent to the sebaceous carcinoma (Figure 1E). Figure 1 Histopathological features of the buttock tumor. A: Bowen’s disease component. Proliferation of atypical squamous cells in the entire layer of acanthotic epidermis accompanied by hyperparakeratosis. HE, x 40. B: These atypical squamous cells have ... Immunohistochemical studies were performed using an autostainer (Ventana) by the same method as previously reported [9-12]. Epithelial membrane antigen (EMA), cytokeratin 7, and Adipophilin were expressed in the sebaceous carcinoma component, but not in Bowen’s disease (Figure 2A). Androgen receptor was also expressed in some of the tumor cells of the sebaceous carcinoma, but not in Bowen’s disease. Moreover, atypical vacuolated cells within the lesion of Bowen’s disease were also positive for Adipophilin (Figure 2B). Overexpression of p53 protein was observed in both the sebaceous carcinoma and Bowen’s disease. Figure 2 Immunohistochemical features of the buttock tumor. A: Adipophilin is diffusely expressed in the sebaceous carcinoma component. x 100. B: Adipophilin-positive atypical cells are present within the lesion of Bowen’s disease. x 200. Accordingly, an ultimate diagnosis of sebaceous carcinoma associated with Bowen’s disease was made. In this report, we describe an extremely rare case of sebaceous carcinoma associated with Bowen’s disease. The peculiar findings of the present case were the presence of Bowen’s disease, which comprised approximately 95% of the tumor, around the sebaceous carcinoma and atypical cells with vacuolated cytoplasm showing positive immunoreactivity for Adipophilin within the lesion of Bowen’s disease. Only a limited number of sebaceous carcinoma cases associated with intraepidermal squamous neoplasia (actinic keratosis or Bowen’s disease) have been documented [3-8]. These cases included sebaceous carcinoma in situ in continuity with intraepidermal squamous neoplasia without association to pre-existing sebaceous glands [3,5,8] and invasive sebaceous carcinoma associated with intraepidermal squamous neoplasia, as seen in the present case [4-8]. Nakashima et al. reported an interesting case of invasive sebaceous carcinoma in continuity with actinic keratosis [6]. In their case, there were intraepidermal atypical cells expressing EMA and Adipophilin, which were also observed in the present case. These Adipophilin-positive intraepidermal atypical cells with vacuolated cytoplasm may represent the tumor cells with sebaceous differentiation. Therefore, they speculated that a close relationship between actinic keratosis and sebaceous carcinoma exists [6]. Moreover, only a limited number of sebaceous carcinoma in situ cases without any association to intraepidermal squamous neoplasia have been reported [2,13]. To the best of our knowledge, there has been no evidence that sebaceous carcinoma arises from pre-existing sebaceous glands [2]. Therefore, these results suggest that extraocular sebaceous carcinoma may originate de novo from intraepidermal pluripotential cells or pre-existing intraepidermal squamous neoplasia.
G Larigauderie - One of the best experts on this subject based on the ideXlab platform.
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perilipin a potential substitute for Adipophilin in triglyceride storage in human macrophages
Atherosclerosis, 2006Co-Authors: G Larigauderie, Christophe Furman, Michael Jaye, Jeancharles Fruchart, Mohamed Amine Bouhlel, Mustapha RouisAbstract:Abnormal lipid deposition in human arteries leads to the formation of fatty streaks due to the accumulation of a large number of macrophage derived-foam cells. The formation and catabolism of intracellular lipid droplets is regulated by droplet-associated proteins. Among such proteins, the role of perilipin in human macrophages was unknown. In this study, we first showed that perilipin expression was increased during differentiation of human monocytes to macrophages. Interestingly, cellular perilipin content was unaffected by treatment of cells with OxLDL, AcLDL, VLDL or sterol esters. Moreover, its expression was not dependent on the presence of Adipophilin, another lipid droplet-associated protein, since it was not affected by transfection of macrophages with siRNA-Adipophilin. Perilipin overexpression in macrophages with an expression vector resulted in significant lipid droplet formation and TG accumulation and this was unaffected by decreasing Adipophilin levels using siRNA. Consequently, perilipin, like Adipophilin, might play an important role in the conversion of macrophages into foam cells and contribute to lesion formation. Therefore, inhibition of Adipophilin might not be sufficient to prevent lesion formation as previously suggested, and perilipin inhibition might be additionally required.
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Adipophilin increases triglyceride storage in human macrophages by stimulation of biosynthesis and inhibition of β oxidation
FEBS Journal, 2006Co-Authors: G Larigauderie, Clarisse Cuazperolin, Amena Ben Younes, Christophe FurmanAbstract:Lipid accumulation alters macrophage biology and contributes to lipid retention within the vessel wall. In this study, we investigated the role of Adipophilin on triglyceride accumulation and lipid-droplet formation in THP-1-derived macrophages (THP-1 macrophages). In the presence of acetylated low-density lipoprotein, macrophages infected with an adenovirus expressing human Adipophilin showed a 31% increase in triglyceride content and a greater number of lipid droplets compared with control cells. Incubation of macrophages with very low-density lipoprotein (VLDL) dramatically increased cellular triglyceride content similarly in control and Adipophilin-overexpressing cells. By itself, VLDL increased Adipophilin expression, which explains the lack of effect of Adipophilin overexpression on cellular triglyceride content in macrophages loaded with VLDL. The lipid-droplet content of macrophages was increased by overexpression of Adipophilin and/or loading with VLDL. In contrast, inhibition of Adipophilin expression using siRNA prevented lipid-droplet formation and significantly reduced intracellular triglyceride content. Using inhibitors of β-oxidation and acyl-coenzyme A synthetase, results were obtained which suggest that Adipophilin elevates cellular lipids by inhibition of β-oxidation and stimulation of long-chain fatty acid incorporation into triglycerides. Adipophilin expression in THP-1 macrophages altered the cellular content of different lipids and enhanced the size of lipid droplets, consistent with a role for Adipophilin in human foam cell formation.
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Adipophilin enhances lipid accumulation and prevents lipid efflux from thp 1 macrophages potential role in atherogenesis
Arteriosclerosis Thrombosis and Vascular Biology, 2004Co-Authors: G Larigauderie, Christophe Furman, Michael Jaye, C Lasselin, Corinne Copin, Jeancharles Fruchart, Graciela Castro, Mustapha RouisAbstract:Objective— Uptake of modified low-density lipoprotein (LDL) by macrophages through scavenger receptors results in lipid droplets accumulation and foam cell formation. Excess lipid deposition in macrophages has been reported to modulate expression of several genes including Adipophilin. In this study, we investigated the function of Adipophilin in lipid accumulation and cholesterol efflux in THP-1 macrophages. Methods and Results— Adipophilin mRNA expression was 3.5-fold higher in human atherosclerotic plaques compared with healthy areas of the same arteries. Moreover, in the presence of acetylated LDL (AcLDL), triglycerides and cholesteryl esters were increased in macrophages overexpressing Adipophilin by 40% and 67%, respectively, whereas their accumulation was reduced when endogenous cellular Adipophilin was depleted using siRNA approach. In addition, neither overexpression nor downregulation of Adipophilin altered expression of genes involved in lipid efflux. However, the affinity and the number of AcLDL receptors were not affected. After 24-hour incubation of lipid-loaded macrophages with apolipoprotein A-I, cholesterol efflux was reduced by 47% in Adipophilin transfected cells versus control cells. Conclusion— Our results showed that stimulation of Adipophilin expression in macrophages by modified LDL promotes triglycerides and cholesterol storage and reduces cholesterol efflux. Therefore, Adipophilin might contribute, in vivo, to lipid accumulation in the intima of the arterial wall.
Tomoharu Sugie - One of the best experts on this subject based on the ideXlab platform.
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Adipophilin expression is an independent marker for poor prognosis of patients with triple negative breast cancer an immunohistochemical study
PLOS ONE, 2020Co-Authors: Katsuhiro Yoshikawa, Mitsuaki Ishida, Hirotsugu Yanai, Koji Tsuta, Mitsugu Sekimoto, Tomoharu SugieAbstract:Adipophilin is a lipid droplet-associated protein whose expression can act as a prognostic marker for specific cancers. Using immunohistochemical staining and tissue microarrays, we assayed the expression of Adipophilin in 61 patients with triple-negative breast cancer (TNBC) who underwent surgery from January 2006-December 2018. Relapse-free survival (RFS) and its risk factors were analyzed based on Adipophilin expression. Fourteen (23.0%) patients expressed Adipophilin. As compared to the Adipophilin-negative TNBC patients, Adipophilin-positive patients exhibited poor RFS (p = 0.032). Among the TNBC patients with a high Ki-67 labeling index, patients negative for Adipophilin exhibited better RFS than patients positive for Adipophilin (p = 0.032). Moreover, among patients who did not undergo adjuvant chemotherapy, patients negative for Adipophilin expression exhibited better RFS than Adipophilin-positive patients (p = 0.080). Multivariate analysis showed that Adipophilin expression correlated with a high rate of relapse (hazard ratio, 4.89; 95% confidence interval, 1.04-23.0; p = 0.044). Taken together, these results indicate that Adipophilin is a novel marker for the poor prognosis of patients with TNBC.
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Adipophilin expression as an independent marker for poor prognosis of patients with triple negative breast cancer
Journal of Clinical Oncology, 2020Co-Authors: Katsuhiro Yoshikawa, Mitsuaki Ishida, Hirotsugu Yanai, Koji Tsuta, Mitsugu Sekimoto, Tomoharu SugieAbstract:e12552Background: Adipophilin (ADP) is a lipid-regulating protein of the perilipin/Adipophilin/tail interacting protein of 47 kDa (PAT) family that coats the surfaces of cytoplasmic lipid droplets....
James L. Mcmanaman - One of the best experts on this subject based on the ideXlab platform.
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Determinants of Adipophilin function in milk lipid formation and secretion
Trends in endocrinology and metabolism: TEM, 2011Co-Authors: Brandi M. Chong, David J. Orlicky, Philip Reigan, Kasey D. Mayle-combs, James L. McmanamanAbstract:In many species the lactating mammary gland is one of the most lipogenic organs of the body. The majority of the lipid produced during lactation is secreted into milk by a novel process of membrane envelopment of cytoplasmic lipid droplets (CLDs). Adipophilin (ADRP/ADPH/PLIN2), a member of the perilipin (PAT) family of lipid droplet proteins, is hypothesized to play a pivotal role in both formation and secretion of milk lipids. Production of milk lipids is the only known example of CLD secretion, and the only process in which PAT family members undergo secretion. This review discusses emerging data on the structural and functional properties of Adipophilin that determine its physiological actions and mediate its effects on milk lipid formation and secretion.
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multiple functions encoded by the n terminal pat domain of Adipophilin
Journal of Cell Science, 2008Co-Authors: David J. Orlicky, Tanya D. Russell, Elise S. Bales, Greg Degala, Carrie Greenwood, James L. McmanamanAbstract:Adipophilin (ADPH), a member of the perilipin family of cytoplasmic lipid droplet (CLD)-binding proteins, is crucially dependent on triglyceride synthesis for stability. We have used cell lines expressing full-length or N-terminally modified forms of ADPH to investigate the role of the N-terminus in regulating ADPH stability and interactions with CLD. Full-length ADPH was unstable and could not be detected on CLDs unless cultures were incubated with oleic acid (OA) to stimulate triglyceride synthesis, or were treated with MG132 to block proteasomal degradation. By contrast, ADPH lacking amino acids 1-89 (Δ 2,3 ADPH), or N-terminally GFP-tagged full-length ADPH, was stable in the absence of OA or MG132, as was the closely related protein TIP47. However, none of these proteins localized to CLDs unless OA was added to the culture medium. Furthermore, immunofluorescence analysis showed that TIP47 localization to CLDs was prevented by full-length ADPH, but not by Δ 2,3 ADPH. These results suggest that the N-terminal region of ADPH mediates proteasomal degradation and access of TIP47 to the CLD surface and possibly contributes to CLD stability. Chimeras of ADPH and TIP47, generated by swapping their N- and C-terminal halves, showed that these properties are specific to ADPH.
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Mammary glands of Adipophilin-null mice produce an amino-terminally truncated form of Adipophilin that mediates milk lipid droplet formation and secretion.
Journal of lipid research, 2007Co-Authors: Tanya D. Russell, David J. Orlicky, Carol A. Palmer, Elise S. Bales, Benny Hung-junn Chang, Lawrence Chan, James L. McmanamanAbstract:Adipophilin (ADPH), a member of the perilipin family of lipid droplet-associated proteins, is hypothesized to mediate milk lipid formation and secretion. Unexpectedly, the fat content of milk from ADPH-null mice was only modestly lower than that of wild-type controls, and neither TIP47 nor perilipin appeared to fully compensate for ADPH loss. This prompted us to investigate the possibility that the mutated ADPH gene was not a genuine null mutation. ADPH transcripts were detected in ADPH-null mammary tissue by quantitative real-time PCR, and C-terminal-specific, but not N-terminal-specific, ADPH antibodies detected a single lower molecular weight product and immunostained cytoplasmic lipid droplets (CLDs) and secreted milk fat globules in ADPH-null mammary tissue. Furthermore, stable cell lines expressing cDNA constructs corresponding to the ADPH-null mutation produced a product comparable in size to the one detected in ADPH-null mammary glands and localized to CLDs. Based on these data, we conclude that ADPH-null mice express an N-terminally truncated form of ADPH that retains the ability to promote the formation and secretion of milk lipids.
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cytoplasmic lipid droplet accumulation in developing mammary epithelial cells roles of Adipophilin and lipid metabolism
Journal of Lipid Research, 2007Co-Authors: Tanya D. Russell, David J. Orlicky, Carol A. Palmer, Andreas Fischer, Michael C Rudolph, Margaret C Neville, James L. McmanamanAbstract:PAT proteins (perilipin, Adipophilin, and TIP47) are hypothesized to be critical regulators of lipid accumulation in eukaryotic cells. We investigated the developmental relationships between the expression of these proteins and cytoplasmic lipid droplet (CLD) accumulation in differentiating secretory epithelial cells in mouse mammary glands. Adipophilin (ADPH) specifically localized to CLD in differentiating and lactating mammary glands and was found exclusively in the secreted lipid droplet fraction of mouse milk. ADPH transcripts were selectively detected in secretory epithelial cells, and steady-state levels of both ADPH mRNA and protein increased during secretory differentiation in patterns consistent with functional linkage to CLD accumulation. TIP47 also was detected in secretory epithelial cells; however, it had a diffuse punctate appearance, and its mRNA and protein expression patterns did not correlate with CLD accumulation. Perilipin-positive adipose cells and steady-state levels of perilipin mRNA and protein decreased during mammary gland differentiation, suggesting a progressive loss of adipose lipid storage during this process. Collectively, these data demonstrate that increased ADPH expression is a specialized property of differentiated secretory epithelial cells and provide developmental evidence specifically linking increased ADPH expression to increased CLD accumulation. In addition, evidence is presented that the epithelial and adipose compartments of the mammary gland undergo concerted, developmentally regulated shifts in lipid metabolism that increase the availability of fatty acids necessary for lipid synthesis by milk-secreting cells.
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lipid droplet targeting domains of Adipophilin
Journal of Lipid Research, 2003Co-Authors: James L. Mcmanaman, William Zabaronick, Jerome Schaack, David J. OrlickyAbstract:Adipophilin (ADPH), a prominent protein com- ponent of lipid storage droplets (LSDs), is postulated to be necessary for the formation and cellular function of these structures. The presence of significant sequence similarities within an � 100 amino acid region of the N-terminal por- tions of ADPH and related LSD binding proteins, perilipin and TIP47, has implicated this region, known as the "PAT" domain, in LSD targeting. Here we investigate the role of the PAT domain in targeting ADPH to LSDs by expressing this region, as well as selected N- and C-terminal trunca- tions of mouse ADPH in COS 7 cells as epitope-tagged fu- sion proteins. Our studies show that truncations lacking ei- ther the PAT domain or the C-terminal half of ADPH both correctly targeted LSDs and increased the LSD content of transfected cells. Neither the PAT domain nor the C-termi- nal half of ADPH appeared to target LSDs or affect the LSD number. Instead, targeting fragments encompassed a putative � -helical region between amino acids 189 and 205, implicating this region in both LSD targeting and regu- lation of LSD formation. —McManaman, J. L., W. Zabaro- nick, J. Schaack, and D. J. Orlicky. Lipid droplet targeting domains of Adipophilin. J. Lipid Res. 2003. 44: 668-673.