The deep population history of East Asia remains poorly understood due to a lack of ancient DNA data and sparse sampling of present-day people 1 , 2 . We report genome-wide data from 166 East Asians dating to 6000 BCE – 1000 CE and 46 present-day groups. Hunter-gatherers from Japan, the Amur River Basin, and people of Neolithic and Iron Age Taiwan and the Tibetan plateau are linked by a deeply-splitting lineage likely reflecting a Late Pleistocene coastal migration. We follow Holocene expansions from four regions. First, hunter-gatherers of Mongolia and the Amur River Basin have ancestry shared by Mongolic and Tungusic language speakers but do not carry West Liao River farmer ancestry contradicting theories that their expansion spread these proto-languages. Second, Yellow River Basin farmers at ~3000 BCE likely spread Sino-Tibetan languages as their ancestry dispersed both to Tibet where it forms up ~84% to some groups and to the Central Plain where it contributed ~59–84% to Han Chinese. Third, people from Taiwan ~1300 BCE to 800 CE derived ~75% ancestry from a lineage also common in modern Austronesian, Tai-Kadai and Austroasiatic speakers likely deriving from Yangtze River Valley farmers; ancient Taiwan people also derived ~25% ancestry from a northern lineage related to but different from Yellow River farmers implying an additional north-to-south expansion. Fourth, Yamnaya Steppe pastoralist ancestry arrived in western Mongolia after ~3000 BCE but was displaced by previously established lineages even while it persisted in western China as expected if it spread the ancestor of Tocharian Indo-European languages. Two later gene flows affected western Mongolia: after ~2000 BCE migrants with Yamnaya and European farmer ancestry, and episodic impacts of later groups with ancestry from Turan.

. The human ACAT-1 cDNA was cloned by a somatic cell and molecular genetic approach. Chinese hamster ovary (CHO) cell mutants lacking ACAT activity (including clone AC29) were isolated (8); subsequent stable transfection experiments showed that human genomic DNAs complemented the ACAT deficiency in AC29 cells (9). A 1.2-kb human genomic DNA fragment was cloned from the stable transfectants. This fragment (designated as G2 DNA) led to the eventual cloning of a full-length human ACAT cDNA K1 (4011 bp in length). Expression of this cDNA, designated as ACAT-1, in AC29 cells complemented the ACAT deficiency of the mutant (10). Additional results showed that expressing this cDNA in insect cells, which do not contain endogenous ACAT-like activity, produced high levels of ACAT activity in vitro, confirming that this cDNA encodes the catalytic component of ACAT enzyme (11). The coding region of the ACAT gene has been mapped to chromosome 1q 25 (12). Protein sequence analysis revealed the ACAT-1 protein as a hydrophobic protein containing multiple transmembrane domains and sharing several peptide regions in common with other acyltransferases (10). Recombinant human ACAT-1 protein expressed in CHO cells has been purified to homogeneity; the homogeneous ACAT-1 protein remains catalytically active and uses cholesterol as a substrate in a highly cooperative manner (13). Homologues of human ACAT-1 cDNA have also been cloned from other species (reviewed in Ref. 1), including two yeast homologues (14,15). Disruption of the ACAT-1 gene in mice has been reported (16); the ACAT-1 gene-deficient mice exhibit marked reduction in cholesteryl ester levels in only selective tissues and not in all the tissues examined. These and other results led to the molecular cloning of ACAT-2 cDNA (17-19). The predicted amino acid sequence of ACAT-2 is homologous but distinct from that of ACAT-1. The physiological roles of ACAT-1 and ACAT-2 in various tissues of different species are currently under intense investigation by several laboratories. In humans, immunodepletion experiments suggest that the ACAT-1 protein plays major catalytic roles in hepatocytes, adrenal glands, macrophages, and kidneys, but not in the intestines (20).The 4.0-kb human ACAT-1 cDNA contains a single open reading frame of 1.65 kb. It also contains an unusually long 5Ј-untranslated region (5Ј-UTR; 1396 bp) and 965 bp of 3Ј-untranslated region. Using the coding region as probe, North-

Exosomes are nanosized membrane vesicles released from cells after fusion of multivesicular bodies (MVBs) with the plasma membrane (PM) and play important roles in intercellular communication and numerous biological processes. However, the molecular mechanisms regulating exosome secretion remain poorly understood. Here we identify KIBRA as an adaptor-like protein that stabilizes Rab27a, which in turn controls exosome secretion both in vitro and in vivo. Knockdown or overexpression of KIBRA in neuronal and podocyte cell lines leads to a decrease or increase of exosome secretion, respectively, and KIBRA depletion increases MVB size and number. Comparing protein profiles between KIBRA knockout and wild-type mouse brain showed significantly decreased Rab27a, a small GTPase that regulates MVB-PM docking. Rab27a is stabilized by interacting with KIBRA, which prevents ubiquitination and degradation via the ubiquitin-proteasome pathway. In conclusion, we show that KIBRA controls exosome secretion via inhibiting the proteasomal degradation of Rab27a.

Acyl-coenzyme A:cholesterol acyltransferase (ACAT)2 is a membrane-bound enzyme present in a variety of tissues and cells. It is mainly located at the endoplasmic reticulum, and catalyzes the biosynthesis of cholesteryl esters, using long-chain fatty acyl-coenzyme A and cholesterol as its substrates. ACAT plays important roles in cholesterol homeostasis. At the single cell level, it is a key enzyme that prevents excess free cholesterol from building up in the cell membranes. At the physiological level, it contributes cholesteryl esters as part of the neutral lipid cargo, to be packaged into the cores of very low density lipoproteins and chylomicrons. Under pathophysiological condition, in cholesterol-loaded macrophages, ACAT converts excess cholesterol into cholesteryl esters. This action reduces the amount of cholesterol available from the macrophage cell surface for efflux and converts the macrophages to foam cells, which are the hallmark of early lesions of the disease atherosclerosis (reviewed in Ref. 1). For these reasons, ACAT has been a drug target for pharmaceutical intervention of diseases, including atherosclerosis and hyperlipidemia. In mammals, two ACAT genes exist that encode for two similar but different proteins, ACAT1 and ACAT2. Available evidence suggests that ACAT1 and ACAT2 may function in distinct and complementary manners in various tissues (reviewed in Refs. 2 and 3). Unlike many other enzymes/proteins involved in cellular cholesterol metabolism, neither ACAT1 nor ACAT2 is regulated at the transcription level by the cholesterol-dependent SREBP (sterol regulatory element-binding protein) cleavage-activating protein (SCAP)/sterol regulatory element-binding protein pathway. Instead, available evidence suggests that ACAT1 may contain a distinct regulatory site that specifically recognizes cholesterol as its activator (4, 5). This mechanism allows ACAT1 to be up-regulated rapidly (within minutes) by cholesterol that builds up at the ER. The enzymological and biochemical characteristics of ACAT2 significantly diverge from those of ACAT1 in several ways; however, ACAT2 may also be allosterically regulated by cholesterol (5, 6).Molecular cloning of the human ACAT1 (hACAT1) gene (7) provided the opportunity to study its biochemical properties. The recombinant hACAT1 expressed in Chinese hamster ovary cells can be purified to homogeneity (8). However, due to the low quantities of protein derived from the purification process, current efforts in our laboratory focus on studies at the enzymological and cell biological levels, but not at the structural biology level. ACAT1 is homotetrameric in vitro and in intact cells (9). The region near the N-terminal contains a dimerization motif. Deleting the N-terminal region converts the enzyme into a homodimer; the dimeric enzyme is fully active catalytically, and remains to be allosterically regulated by cholesterol (10). ACAT1 contains multiple transmembrane domains (TMDs). To deduce its membrane topology, we had previously inserted the nine-amino acid HA tag a...

Acyl-CoA:cholesterol acyltransferase (ACAT) is a membrane-bound enzyme that produces cholesteryl esters intracellularly. Two ACAT genes (ACAT1 and ACAT2) have been identified. The expression of ACAT1 is ubiquitous, whereas that of ACAT2 is tissue restricted. Previous research indicates that ACAT1 may contain seven transmembrane domains (TMDs). To study ACAT2 topology, we inserted two different antigenic tags (hemagglutinin, monoclonal antibody Mab1) at various hydrophilic regions flanking each of its predicted TMDs, and expressed the recombinant proteins in mutant Chinese hamster ovary cells lacking endogenous ACAT. Each tagged ACAT2 was expressed in the endoplasmic reticulum as a single undegraded protein band and was at least partially active enzymatically. We then used cytoimmunofluorescence and protease protection assays to monitor the sidedness of the hemagglutinin and Mab1 tags along the ER membranes. The results indicated that ACAT2 contains only two detectable TMDs, located near the N terminal region. We also show that a conserved serine (S245), a candidate active site residue, is not essential for ACAT catalysis. Instead, a conserved histidine (H434) present within a hydrophobic peptide segment, may be essential for ACAT catalysis. H434 may be located at the cytoplasmic side of the membrane.

Objective To investigate the prevalence and associated factors of poor sleep quality among community-dwelling elderly population in a rural area of Northern China. Methods We conducted a cross-sectional survey in August-December 2014 and recruited 2195 participants who were aged 65 years or older and living in Yanlou Town of Yanggu County in western Shandong Province, China. Data on demographics, health-related behaviors, and clinical conditions were collected through structured interviews. The Pittsburgh Sleep Quality Index (PSQI) was used to assess the sleep quality and patterns. Poor sleep quality was defined as a PSQI score > 7. We employed multiple logistic models to relate poor sleep quality to various factors. Results The overall prevalence rates of poor sleep quality were 33.8% in the total sample, 39.2% in women and 26.3% in men (P < 0.01). The most common abnormal sleep domains were prolonged sleep latency (39.7%), decreased sleep duration (31.0%), and reduced habitual sleep efficiency (28.8%). Multiple logistic regression analyses revealed that poor sleep quality was significantly associated with female sex (OR = 1.76, 95% CI 1.46-2.12) and clinical comorbidities such as hypertension (OR = 1.28, 95% CI 1.06-1.54), coronary heart disease (OR = 1.60, 95% CI 1.27-2.00), and chronic obstructive pulmonary disease (OR = 1.82, 95% CI 1.34-2.49). Conclusions The sleep disorders were highly prevalent among the elderly in rural China. Modifiable risk factors such as cardiometabolic risk factors and disorders were associated with poor sleep quality, which might be potential targets for interventions to improve sleep quality in elderly population.

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