NCBI Summary:
The protein encoded by this gene has a long and a short form, generated by use of alternative translational start codons. The long form is expressed in steroidogenic tissues such as testis, where it converts cholesteryl esters to free cholesterol for steroid hormone production. The short form is expressed in adipose tissue, among others, where it hydrolyzes stored triglycerides to free fatty acids. [provided by RefSeq, Jul 2008]
General function
Enzyme
Comment
Cellular localization
Comment
Omental adipose tissue overexpression of fatty acid transporter CD36 and decreased expression of hormone-sensitive lipase in insulin-resistant women with polycystic ovary syndrome. Seow KM et al. (2009) Elevated free fatty acids (FFAs) are involved in insulin resistance in polycystic ovary syndrome (PCOS). We investigated the role of fatty acid transporter CD36, hormone-sensitive lipase (HSL) and adipose triglyceride lipase (ATGL) in regulation of lipolysis in insulin-resistant women with PCOS. CD36, HSL and ATGL proteins were analyzed in omental adipose tissue from 10 women with PCOS and 10 healthy, BMI- and age-matched controls by western blotting. Women with PCOS had higher fasting and 2 h insulin levels (P < 0.002, P < 0.029, respectively) and a higher homeostasis model insulin resistance index (P < HOMA(IR), 0.005) and a lower fasting glucose-to-insulin ratio (G(0)/I(0)) (P < 0.001) than controls. CD36 protein levels in the PCOS women were higher (268% of control levels, P < 0.05) and HSL protein levels were lower (43% of control levels, P < 0.05). However, ATGL protein levels were not different in the two groups. Fasting serum insulin levels showed a positive correlation with CD36 levels (P = 0.01, r = 0.875) and a negative correlation with HSL levels (P = 0.045, r = -0.73). Furthermore, a positive correlation was found between serum testosterone levels and CD 36 protein levels (P = 0.025, r = 0.817) but the correlation did not reach significance after controlling for HOMA(IR). After adjusting insulin resistance index of HOMA(IR) by analysis of covariance, only CD36 differed between PCOS and control (P = 0.026). Our results suggest that, in insulin-resistant women with PCOS, changes in CD36 and HSL expression may result in altered FFA uptake.//////////////////
Ovarian function
Steroid metabolism, Luteinization
Comment
Trafficking of cholesterol from lipid droplets to mitochondria in bovine luteal cells: Acute control of progesterone synthesis. Plewes MR et al. (2020) The corpus luteum is a transient endocrine gland that synthesizes and secretes the steroid hormone, progesterone, which is vital for establishment and maintenance of pregnancy. Luteinizing hormone (LH) via activation of protein kinase A (PKA) acutely stimulates luteal progesterone synthesis via a complex process, converting cholesterol via a series of enzymatic reactions, into progesterone. Lipid droplets in steroidogenic luteal cells store cholesterol in the form of cholesterol esters, which are postulated to provide substrate for steroidogenesis. Early enzymatic studies showed that hormone sensitive lipase (HSL) hydrolyzes luteal cholesterol esters. In this study, we tested whether HSL is a critical mediator of the acute actions of LH on luteal progesterone production. Using LH-responsive bovine small luteal cells our results reveal that LH, forskolin, and 8-Br cAMP-induced PKA-dependent phosphorylation of HSL at Ser563 and Ser660, events known to promote HSL activity. Small molecule inhibition of HSL activity and siRNA-mediated knock down of HSL abrogated LH-induced progesterone production. Moreover, western blotting and confocal microscopy revealed that LH stimulates phosphorylation and translocation of HSL to lipid droplets. Furthermore, LH increased trafficking of cholesterol from the lipid droplets to the mitochondria, which was dependent on both PKA and HSL activation. Taken together, these findings identify a PKA/HSL signaling pathway in luteal cells in response to LH and demonstrate the dynamic relationship between PKA, HSL, and lipid droplets in luteal progesterone synthesis.//////////////////
Expression regulated by
Comment
Ovarian localization
Oocyte, Granulosa, Theca, Luteal cells
Comment
Hormone-sensitive Lipase Expression and Immunohistochemical Localization in the Rat Ovary, Oviduct, and Uterus. Lobo MV et al. Hormone-sensitive lipase (HSL) is a key regulator of cholesterol esters metabolism .The aim of this study was to determine HSL localization in rat female reproductive organs during the ovarian cycle by immunohistochemical methods. HSL was located in the ovarian epithelium. The granulosa cells and oocytes of primordial follicles were immunonegative. In mature follicles, HSL was found in oocytes, theca and granulosa cells. However, HSL expression in theca cells and oocytes decreased during follicular atresia. Luteal cells showed HSL staining in cytoplasm during proestrus and estrus, in nucleus during metestrus, and cytoplasm and nucleus during diestrus. In the tubaric ampulla, HSL was located in the epithelial cells nuclei and in the cilia during proestrus and estrus, but mainly in nucleus during metestrus and diestrus. In the isthmus, cells showed HSL immunolabelling in the nucleus and cilia during proestrus, but only in the cilia during estrus, metestrus and diestrus. In the uterus, HSL was found in the epithelial cells nuclei. HSL-immunoreactive bands at 84, 67, 54 and 43 kDa were found in rat female reproductive organs. HSL labelling in the nucleus of epithelial and germ cells suggests an, as yet, unknown function for this protein, probably related to oogenesis and cell proliferation.