title: Nutritional, hormonal, and depot-dependent regulation of the expression of the small GTPase Rab18 in rodent adipose tissue.
abstract: There is increasing evidence that proteins associated with lipid droplets (LDs) play a key role in the coordination of lipid storage and mobilization in adipocytes. The small GTPase, RAB18, has been recently identified as a novel component of the protein coat of LDs and proposed to play a role in both β-adrenergic stimulation of lipolysis and insulin-induced lipogenesis in 3T3-L1 adipocytes. In order to better understand the role of Rab18 in the regulation of lipid metabolism in adipocytes, we evaluated the effects of age, fat location, metabolic status, and hormonal milieu on Rab18 expression in rodent white adipose tissue (WAT). Rab18 mRNA was undetectable at postnatal day 15 (P15), but reached adult levels by P45, in both male and female rats. In adult rats, Rab18 immunolocalized around LDs, as well as within the cytoplasm of mature adipocytes. A weak Rab18 signal was also detected in the stromal-vascular fraction of WAT. In mice, fasting significantly increased, though with a distinct time-course pattern, Rab18 mRNA and protein levels in visceral and subcutaneous WAT. The expression of Rab18 was also increased in visceral and subcutaneous WAT of obese mice (diet-induced, ob/ob, and New Zealand obese mice) compared with lean controls. Rab18 expression in rats was unaltered by castration, adrenalectomy, or GH deficiency but was increased by hypophysectomy, as well as hypothyroidism. When viewed together, our results suggest the participation of Rab18 in the regulation of lipid processing in adipose tissue under both normal and pathological conditions.
authors.affiliation: Department of Cell Biology, Physiology and Immunology, Instituto Maimónides de Investigación Biomédica de Córdoba, University of Córdoba/Hospital Universitario Reina Sofia, Edificio Severo-Ochoa, Pl. 3, Campus Univ. de Rabanales, E-14014 Córdoba, Spain.
authors.forename: Marina R
authors.initials: MR
authors.lastname: Pulido
authors.forename: Yoana
authors.initials: Y
authors.lastname: Rabanal-Ruiz
authors.forename: Farid
authors.initials: F
authors.lastname: Almabouada
authors.forename: Alberto
authors.initials: A
authors.lastname: Díaz-Ruiz
authors.forename: María A
authors.initials: MA
authors.lastname: Burrell
authors.forename: María J
authors.initials: MJ
authors.lastname: Vázquez
authors.forename: Justo P
authors.initials: JP
authors.lastname: Castaño
authors.forename: Rhonda D
authors.initials: RD
authors.lastname: Kineman
authors.forename: Raúl M
authors.initials: RM
authors.lastname: Luque
authors.forename: Carlos
authors.initials: C
authors.lastname: Diéguez
authors.forename: Rafael
authors.initials: R
authors.lastname: Vázquez-Martínez
authors.forename: María M
authors.initials: MM
authors.lastname: Malagón
mesh_terms: D000273:Adipose Tissue / Q000201:enzymology* / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D017931:DNA Primers; D004032:Diet; D005260:Female; D006728:Hormones / Q000502:physiology*; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009765:Obesity / Q000201:enzymology / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D011917:Rats, Inbred Lew; D017207:Rats, Sprague-Dawley; D060888:Real-Time Polymerase Chain Reaction; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D006728:Hormones; C484168:RAB18 protein, human; D012333:RNA, Messenger; D020691:rab GTP-Binding Proteins