Limor Ziv - Academia.edu (original) (raw)

Papers by Limor Ziv

Biomedicines

Background: Gain-of-function mutations in CARD14 have recently been shown to be involved in the p... more Background: Gain-of-function mutations in CARD14 have recently been shown to be involved in the pathogenesis of psoriasis and pityriasis rubra pilaris (PRP). Those mutations were found to activate the NF-kB signaling pathway. Objective: Zebrafish is often used to model human diseases in general, and in skin disorders more particularly. In the present study, we aimed to examine the effect of CARD14 overexpression in zebrafish with the aim to validate this model for future translational applications. Methods: We used light microscopy, scanning electron microscopy, histological analysis and whole mount in situ hybridization as well as real-time PCR to ascertain the effect of CARD14 overexpression in the developing zebrafish. Results: Overexpression of human CARD14 had a marked morphological and developmental effect on the embryos. Light microscopy demonstrated a characteristic cutaneous pattern including a granular surface and a spiky pigment pattern. In situ hybridization revealed ker...

Journal of Investigative Dermatology, 2018

Human Genetics, 2017

c.C283T, p.R95W). Since FHL1 has not been linked to calcium regulation before, we provide evidenc... more c.C283T, p.R95W). Since FHL1 has not been linked to calcium regulation before, we provide evidence for its functional role in hypoparathyroidism by: (i) bioinformatics analysis coupling its action to known modulators of PTH function; (ii) observing strong expression of fhl1b in Corpuscles of Stannius, gland-like aggregates in zebrafish that function in calcium regulation similar to mammalian PTH; and (iii) implicating fhl1b and FHL1 as regulators of calcium homeostasis in zebrafish and human cells, respectively. Altogether, our data suggest that FHL1 is a novel regulator of calcium homeostasis and implicate it as the causative gene for X-linked recessive hypoparathyroidism.

Clinical Genetics, 2016

intractable seizures and developmental delay caused by biallelic variants in TBCD: further deline... more intractable seizures and developmental delay caused by biallelic variants in TBCD: further delineation of a new chaperone-mediated tubulinopathy.

PLoS genetics, 2016

Despite recent advances in our understanding of the pathogenesis of ectodermal dysplasias (EDs), ... more Despite recent advances in our understanding of the pathogenesis of ectodermal dysplasias (EDs), the molecular basis of many of these disorders remains unknown. In the present study, we aimed at elucidating the genetic basis of a new form of ED featuring facial dysmorphism, scalp hypotrichosis and hypodontia. Using whole exome sequencing, we identified 2 frameshift and 2 missense mutations in TSPEAR segregating with the disease phenotype in 3 families. TSPEAR encodes the thrombospondin-type laminin G domain and EAR repeats (TSPEAR) protein, whose function is poorly understood. TSPEAR knock-down resulted in altered expression of genes known to be regulated by NOTCH and to be involved in murine hair and tooth development. Pathway analysis confirmed that down-regulation of TSPEAR in keratinocytes is likely to affect Notch signaling. Accordingly, using a luciferase-based reporter assay, we showed that TSPEAR knock-down is associated with decreased Notch signaling. In addition, NOTCH1 pr...

Journal of Investigative Dermatology, 2016

Hairless mice were first described over 150 years ago in the form of the severe rhino mouse mutat... more Hairless mice were first described over 150 years ago in the form of the severe rhino mouse mutation (Hr rh) closely followed by a more mild phenotypic allele named hairless (Hr hr). Eventually both these alleles were established in both inbred and outbred mouse colonies. About 30 years ago these mice, primarily the hairless allele as it was called with the milder phenotype, became commonly used for skin cancer research, both UV light and chemical carcinogen induced, as the mice lacked hair as adults and were considered by many to be useful models of normal human skin. Subsequently, it was found that the Hr was a good model of papular atrichia. Today, there is a rich, but possibly confusing, landscape of different mutant Hr alleles present on a multitude of inbred, outbred, congenic, and segregating mouse strains. To confound this problem further there are also a number of mutant Hr phenocopies, i.e. mouse strains with mutations in genes that mimic the hairless phenotype, such as mutant alleles in the Vdr, Odc1, and other genes in the putrescine pathway. In this overview, we will clarify the phenotypes, genotypes, and mouse strain considerations that need to be accounted for when designing a study and interpreting the results of studies using these mice including many new alleles, both spontaneous and genetically engineered.

Frontiers in behavioral neuroscience, 2012

One function of glucocorticoids is to restore homeostasis after an acute stress response by provi... more One function of glucocorticoids is to restore homeostasis after an acute stress response by providing negative feedback to stress circuits in the brain. Loss of this negative feedback leads to elevated physiological stress and may contribute to depression, anxiety, and post-traumatic stress disorder. We investigated the early, developmental effects of glucocorticoid signaling deficits on stress physiology and related behaviors using a mutant zebrafish, gr(s357), with non-functional glucocorticoid receptors (GRs). These mutants are morphologically inconspicuous and adult-viable. A previous study of adult gr(s357) mutants showed loss of glucocorticoid-mediated negative feedback and elevated physiological and behavioral stress markers. Already at 5 days post-fertilization, mutant larvae had elevated whole body cortisol, increased expression of pro-opiomelanocortin (POMC), the precursor of adrenocorticotropic hormone (ACTH), and failed to show normal suppression of stress markers after ...

Proceedings of the National Academy of Sciences, 2006

The zebrafish pineal gland is a photoreceptive organ containing an intrinsic central circadian os... more The zebrafish pineal gland is a photoreceptive organ containing an intrinsic central circadian oscillator, which drives daily rhythms of gene expression and the melatonin hormonal signal. Here we investigated the effect of light, given at early developmental stages before pineal gland formation, on the pineal circadian oscillator. Embryos that were exposed to light at 0–6, 10–13, or 10–16 h after fertilization exhibited clock-controlled rhythms of arylalkylamine- N -acetyltransferase ( zfaanat2 ) mRNA in the pineal gland during the third and fourth day of development. This rhythm was absent in embryos that were placed in continuous dark within 2 h after fertilization (before blastula stage). Differences in the phases of these rhythms indicate that they are determined by the time of illumination. Light treatments at these stages also caused a transient increase in period2 mRNA levels, and the development of zfaanat2 mRNA rhythm was abolished by PERIOD2 knock-down. These results indic...

Neuroscience Research, 2007

Concomitant activation of ACC and DLPFC has been linked to cuereactivity, but their differences a... more Concomitant activation of ACC and DLPFC has been linked to cuereactivity, but their differences are not known. We studied the role of DLPFC using rTMS that reduces excitability of the targeted cortex. Ten smokers received four fMRI scans on different days, during which they viewed smoking-cue video. Each of four fMRI was scanned under different conditions of expectancy (non-expectant vs. expectant) and rTMS (true vs. sham) performed immediately before scan. Repeated TMS was targeted previously identified left DLPFC. In the true TMS condition, we found lowered self-reporting cue-induced craving and lack of cue-induced BOLD increase in the ACC and a correlation between craving and BOLD signal in the left DLPFC, both observed during the expectant and the sham rTMS conditions. The left DLPFC became less responsive to input from the contralateral DLPFC and medial temporal regions, but not to ACC. These findings suggest that DLPFC associates perceived drug availability with craving in a positive feed-forward manner.

Molecular Psychiatry, 2012

Upon binding of cortisol, the glucocorticoid receptor (GR) regulates the transcription of specifi... more Upon binding of cortisol, the glucocorticoid receptor (GR) regulates the transcription of specific target genes, including those that encode the stress hormones corticotropin-releasing hormone (CRH) and adrenocorticotropic hormone. Dysregulation of the stress axis is a hallmark of major depression in human patients. However, it is still unclear how glucocorticoid signaling is linked to affective disorders. We identified an adult-viable zebrafish mutant in which the negative feedback on the stress response is disrupted, due to abolition of all transcriptional activity of GR. As a consequence, cortisol is elevated, but unable to signal through GR. When placed into an unfamiliar aquarium ('novel tank'), mutant fish become immobile ('freeze'), show reduced exploratory behavior and do not habituate to this stressor upon repeated exposure. Addition of the antidepressant fluoxetine to the holding water and social interactions restore normal behavior, followed by a delayed correction of cortisol levels. Fluoxetine does not affect the overall transcription of CRH, the mineralocorticoid receptor (MR), the serotonin transporter (Serta) or GR itself. Fluoxetine, however, suppresses the stress-induced upregulation of MR and Serta in both wild-type fish and mutants. Our studies show a conserved, protective function of glucocorticoid signaling in the regulation of emotional behavior and reveal novel molecular aspects of how chronic stress impacts vertebrate brain physiology and behavior. Importantly, the zebrafish model opens up the possibility of high-throughput drug screens in search of new classes of antidepressants.

Journal of Neuroendocrinology, 2005

In zebrafish, the pineal gland is a photoreceptive organ that contains an intrinsic circadian osc... more In zebrafish, the pineal gland is a photoreceptive organ that contains an intrinsic circadian oscillator and exhibits rhythmic arylalkylamine-N-acetyltransferase (zfaanat2) mRNA expression. In the present study, we investigated the role of light and of a clock gene, zperiod2 (zper2), in the development of this rhythm. Analysis of zfaanat2 mRNA expression in the pineal gland of 3-day-old zebrafish embryos after exposure to different photoperiodic regimes indicated that light is required for proper development of the circadian clock-controlled rhythmic expression of zfaanat2, and that a 1-h light pulse is sufficient to initiate this rhythm. Analysis of zper2 mRNA expression in zebrafish embryos exposed to different photoperiodic regimes indicated that zper2 expression is transiently up-regulated by light but is not regulated by the circadian oscillator. To establish the association between light-induced zper2 expression and light-induced clock-controlled zfaanat2 rhythm, zPer2 knock-down experiments were performed. The zfaanat2 mRNA rhythm, induced by a 1-h light pulse, was abolished in zPer2 knock-down embryos. These experiments indicated that light-induced zper2 expression is crucial for establishment of the clock-controlled zfaanat2 rhythm in the zebrafish pineal gland.

Journal of Molecular Endocrinology, 2006

Daily rhythms of melatonin production are controlled by changes in the activity of arylalkylamine... more Daily rhythms of melatonin production are controlled by changes in the activity of arylalkylamine-N-acetyltransferase (AANAT). Zebrafish possess two aanats, aanat1 and aanat2; the former is expressed only in the retina and the latter is expressed in both the retina and the pineal gland. Here, their differential expression and regulation were studied using transcript quantification and transient and stable in vivo and in vitro transfection assays. In the pineal gland, the aanat2 promoter exhibited circadian clock-controlled activity, as indicated by circadian rhythms of Enhanced green fluorescent protein (EGFP) mRNA in AANAT2:EGFP transgenic fish. In vivo transient expression analyses of the aanat2 promoter indicated that E-box and photoreceptor conserved elements (PCE) are required for expression in the pineal gland. In the retina, the expression of both genes was characterized by a robust circadian rhythm of their transcript levels. In constant darkness, the rhythmic expression of ...

Experimental Eye Research, 2007

The pineal gland of the zebrafish (Danio rerio) is a clock-containing photoreceptive organ. Super... more The pineal gland of the zebrafish (Danio rerio) is a clock-containing photoreceptive organ. Superfused pineal glands kept in darkness display rhythmic melatonin production that lasts for days, with high melatonin levels during the night and low levels during the day. Nocturnal light, however, evokes an acute suppression of melatonin synthesis in the photoreceptor cells. Towards characterizing zebrafish pineal photopigment that is involved in the acute melatonin suppression we have measured the spectral sensitivity of melatonin-suppression response in superfused pineal glands. The effect of 2 h light exposure of seven wavelengths (l avg 408, 460, 512, 560, 608, 660 and 697 AE 10e15 nm) at multiple irradiances (10 7 e10 14 photons/cm 2 /s) was determined, and an action spectrum was plotted. The resultant action spectrum provides evidence for the involvement of multiple photopigments in melatonin suppression. The most efficient melatonin-suppression response was achieved by exposure to light of around 512 nm; however, another peak of lower irradiance sensitivity was observed in the middle to long wavelengths. Opsins-specific RT-PCR analysis confirmed the expression of exo-rhodopsin and visual red-sensitive opsin in the pineal gland, while other zebrafish visual opsins as well as VA and VAL opsins were not detected. Dartnall monograms for exo-rhodopsin and visual red-sensitive opsin account for most but not all of the spectral sensitivity features. Therefore, additional pineal photopigments may contribute to the melatonin-suppression response in the pineal gland.

Chronobiology International, 2006

In zebrafish, pineal arylalkylamine-N-acetyltransferase (zfaanat2) mRNA expression begins at 22 h... more In zebrafish, pineal arylalkylamine-N-acetyltransferase (zfaanat2) mRNA expression begins at 22 h post-fertilization (hpf), and the clock-controlled rhythm of its transcript begins on the third day of development. Here we describe the role of light and of the clock gene, period2 (zper2) in the development of this rhythm. In 1-day-old zebrafish embryos, zper2 expression is transiently up-regulated by light in the pineal gland and, to a lesser extent, in other areas of the brain. Expression of zper2 that was not affected by light occurred in the olfactory placode and lactotroph cells of the pituitary primordium. Circadian analysis of pineal zfaanat2 mRNA expression indicated that light exposure is required for proper development of the circadian clock-controlled rhythmic expression of this gene. Knockdown of zPER2 using antisense technology abolished the effect of light on development of the zfaanat2 rhythm in the pineal gland, corroborating the role of zper2 in light entrainment of the circadian oscillator in zebrafish. Further analysis of zper2 expression at earlier stages of development revealed that light exposure at the blastula to mid-segmentation stages also caused a transient increase in zper2 expression. At mid-segmentation, before pineal differentiation, light-induced zper2 expression was enhanced in pineal progenitor cells. Thus, a possible role for early photoreception and light-induced zper2 expression in the development of clock-controlled rhythms remains to be investigated.

The zebrafish pineal gland is a photoreceptive organ that contains an intrinsic circadian oscilla... more The zebrafish pineal gland is a photoreceptive organ that contains an intrinsic circadian oscillator which drives daily rhythms of gene expression and the melatonin hormonal signal. Circadian rhythms of melatonin in the blood, peaking at night are design to modulate circadian and annual rhythms in all vertebrates. The source of rhythmic melatonin secretion is daily changes in the activity of Arylalkylamin Nacetyl transferase (AANAT). Zebrafish AANAT (zfAANAT2) activity is regulated by light and by the circadian oscillator in the pineal gland. Light pulse during the night triggers an acute degradation of AANAT protein in the pineal photoreceptor cell. In addition, daily-rhythmic transcription of zfaanat2 is regulated by the circadian oscillator. In zebrafish embryos, zfAanat2 mRNA expression begins at 22 h postfertilization (hpf), soon after the pineal is formed and clock-controlled rhythm of its transcript begins on the second day of development. In the studies presented here, I hav...