HSF1 Research Articles

Heat stress induces expression of HSP genes in genetically divergent chickens

BackgroundChickens are animals that are sensitive to thermal stress, which may decrease their production level in terms that it affects feed intake and thus, decreasing body weight gain. The Heat Shock Factors (HSF) and Heat Shock Proteins (HSP) genes are involved in the key cellular defense mechanisms during exposure in hot environments. Aimed with this study to analyze the expression of HSF1, HSF3, HSP70 and HSP90 genes in two local breeds (Peloco and Caneluda) and a commercial broiler line (Cobb 500®) to verify differences in resistance of these chicken to Heat stress treatment. Chicken were submitted to heat stress under an average temperature of 39°C ± 1.ResultsUnder stress environment, the HSP70 and HSP90 genes were more expressed in backyard chickens than in broiler. There was a difference in HSP70 and HSP90 expression between Caneluda and Cobb and between Peloco and Cobb under stress and comfort environment respectively. HSP70 expression is higher in local breeds during heat stress than in a commercial broiler line. No significant differences were observed in the expression of HSF1 and HSF3 genes between breeds or environments.ConclusionsHSP70 and HSP90 genes are highly expressed, HSF1 and HSF3 genes did not have high expression in all genetic groups. HSP70 and HSP90 are highly expressed in Peloco and Caneluda within heat stress, these breeds proved to be very resistant to high temperature.

Splice variants and seasonal expression of buffalo HSF genes.

In eukaryotes, the heat shock factors (HSFs) are recognized as the master regulator of the heat shock response. In this respect, the genes encoding the heat shock factors seem to be important for adaptation to thermal stress in organisms. Despite this, only few mammalian HSFs has been characterized. In this study, four major heat shock factor genes viz. HSF-1, 2, 4, and 5 were studied. The main objective of the present study was to characterize the cDNA encoding using conserved gene specific primers and to investigate the expression status of these buffalo HSF genes. Our RT-PCR analysis uncovered two distinct variants of buffalo HSF-1 and HSF-2 gene transcripts. In addition, we identified a variant of the HSF5 transcript in buffalo lacking a DNA-binding domain. In silico analysis of deduced amino acid sequences for buffalo HSF genes showed domain architecture similar to other mammalian species. Changes in the gene expression profile were noted by quantitative real-time PCR (qRT-PCR) analysis. We detected the transcript of buffalo HSF genes in different tissues. We also evaluated the seasonal changes in the expression of HSF genes. Interestingly, the transcript level of HSF-1 gene was found upregulated in months of high and low ambient temperatures. In contrast, the expression of the HSF-4 and 5 genes was found to be downregulated in months of high ambient temperature. This suggests that the intricate balance of different HSFs is adjusted to minimize the effect of seasonal changes in environmental conditions. These findings advance our understanding of the complex, context-dependent regulation of HSF gene expression under normal and stressful conditions.

Hsp90, Hsp60 and HSF-1 genes expression in muscle, heart and brain of thermally manipulated broiler chicken

The effect of thermal manipulation (TM) during embryogenesis (ED 12–18) on mRNA expressions of heat shock proteins (Hsp90, Hsp60 and HSF-1) in muscle, heart and brain tissues during thermal challenge (TC) at post-hatching days 10 and 28 was investigated. Fertile chicken eggs were randomly divided into four groups: Control group (37.8 °C), TM1 (39 °C for 9 h), TM2 (39 °C for 12 h) and TM3 (39 °C for 18 h). At days 10 and 28 of age, chicks in TC groups were subjected to thermal challenge (TC) at 43.0 °C for 6 h while naïve chicks were kept under regular conditions. When compared with the control, TM resulted in a significant increase in mRNA levels of Hsp90, Hsp60 and HSF-1in muscle, heart and brain tissues during embryogenesis and during TC at days 10 and 28 post-hatching. These results indicate a long-term enhancement of Hsp90, Hsp60 and HSF-1 gene expressions associated with improved thermotolerance acquisition in thermally manipulated chicks.

A novel p.Glu75Lys mutation in CRYBB1 with low penetrance in an Indian family with nuclear form of congenital cataract

IntroductionTo screen CRYAA, CRYAB, CRYGC, CRYGD, CRYGS, CRYBA1, CRYBA4, CRYBB1, CRYBB2, CRYBB3, BFSP1, GJA3, GJA8 and HSF4 gene in an Indian family having congenital cataract. MethodsThe congenital cataract family presented at Dr. R.P. Centre for Ophthalmic Sciences, a tertiary research and referral hospital (AIIMS, New Delhi, India). CRYAA, CRYAB, CRYGC, CRYGD, CRYGS, CRYBA1, CRYBA4, CRYBB1, CRYBB2, CRYBB3, BFSP1, GJA3, GJA8 and HSF4 genes were amplified. Protein structure differences analysis was performed using Discovery Studio (DS) 2.0. ResultsA three-generation Indian family with diagnosis of congenital cataract presented with bilateral dense nuclear opacities in the affected individuals. Direct sequencing analysis of 14 genes identified a novel and pathogenic nucleotide variation p.E75K in CRYBB1 gene. The mutation p.Glu75Lys alters the environment and charge on the protein surface, disrupting ionic interaction between Glu75 and Arg60. Thus p.Glu75Lys changes the electrostatic potential of the protein surface which could affect the interactions with other interacting partner proteins. DiscussionsIn this case a novel heterozygous p.Glu75Lys mutation in CRYBB1 was detected in an Indian family with nuclear cataract. The mutation was inherited in autosomal dominant pattern and showed reduced penetrance. Identification and characterization of this mutation further confirm the importance of protein interactions in maintaining lens transparency, and provides insight into the molecular mechanism underlying the pathogenesis of human congenital cataract.

High transcript levels of heat-shock genes are associated with shorter lifespan of Caenorhabditis elegans

Individual lifespans of isogenic organisms, such as Caenorhabditis elegans nematodes, fruit flies, and mice, vary greatly even under identical environmental conditions. To study the molecular mechanisms responsible for such variability, we used an assay based on the measurement of post-reproductive nematode movements stimulated by a moderate electric field. This assay allows for the separation of individual nematodes based on their speed. We show that this phenotype could be used as a biomarker for aging because it is a better predictor of lifespan than chronological age. Fast nematodes have longer lifespans, fewer protein carbonyls, higher heat-shock resistance, and higher transcript levels of the daf-16 and hsf-1 genes, which code for the stress response transcription factors, than slow nematodes. High transcript levels of the genes coding for heat-shock proteins observed in slow nematodes correlate with lower heat-shock resistance, more protein carbonyls, and shorter lifespan. Taken together, our data suggests that shorter lifespan results from early-life damage accumulation that causes subsequent faster age-related deterioration.

Expression of the HSF4 DNA binding domain-EGFP hybrid gene recreates early childhood lamellar cataract in transgenic mice.

The clinical management of cataracts in infancy involves surgical removal of the lens to ensure transmission of light to the retina, which is essential for normal neural development of the infant. This surgery, however, entails a lifelong follow-up and impaired vision. To our knowledge, no animal models recapitulate human lamellar opacities, the most prevalent form of early childhood cataracts. We present data on the recreation of the human lamellar cataract phenotype in transgenic mice. Mutations in the DNA binding domain (DBD) of the heat shock transcription factor 4 (HSF4) are known to be associated with early childhood autosomal dominant lamellar cataract. We used bacterial artificial chromosome (BAC) transgenesis to express a hybrid gene: Hsf4 (DBD)-enhanced green fluorescent protein (EGFP), by recombineering EGFP sequences into the DBD of the Hsf4 gene, to interfere with the DNA binding properties of Hsf4. We recapitulated the human lamellar cataract, in its temporal as well as spatial presentation, within the transgenic mouse lens. This phenotype was reproduced faithfully using four different BACs, indicating that EGFP can be used to target transcription factor function in transgenic mice. Molecular and cell biological examination of early postnatal transgenic lens reveals impairment of secondary fiber cell differentiation. Recreation of the human lamellar cataract phenotype in mice allows investigation of this human pathology at a level not possible previously and points to the relevance of fiber cell heterogeneity dictated by fiber cell-specific gene activity in the biogenesis of the lamellar cataract.

Neonatal capsaicin treatment in rats affects TRPV1-related noxious heat sensation and circadian body temperature rhythm

The transient receptor potential vanilloid 1 (TRPV1) is a cation channel that serves as a polymodal detector of noxious stimuli such as capsaicin. Therefore, capsaicin treatment has been used to investigate the physiological function of TRPV1. Here, we report physiological changes induced by treating neonatal rats with capsaicin. Capsaicin (50mg/kg) (cap-treated) or vehicle (vehicle-treated) was systemically administered to newborn SD rat pups within 48h after birth. TRPV1 expression, intake volume of capsaicin water, and noxious heat sensation were measured 6weeks after capsaicin treatment. Circadian body temperature and locomotion were recorded by biotelemetry. Expression of Per1, Per2, Bmal1 and Hsf1 (clock genes) was also investigated. Neonatal capsaicin treatment not only decreased TRPV1 expression but also induced desensitization to noxious heat stimuli. Circadian body temperature of cap-treated rats increased significantly compared with that of vehicle-treated rats. Additionally, the amplitude of the circadian body temperature was reversed in cap-treated rats. Expression of the hypothalamic Hsf1 and liver Per2 clock genes followed a similar trend. Therefore, we suggest that these findings will be useful in studying various physiological mechanisms related to TRPV1.

Identification and functional characterization of heat shock transcription factor1 in Litopenaeus vannamei

Heat shock transcription factors belong to the heat shock factor (HSF) protein family, which are involved in heat shock protein (HSP) gene regulation. They are critical for cell survival upon exposure to harmful conditions. In this study, we identified and characterized a HSF1 (LvHSF1) gene in Litopenaeus vannamei, with a full-length cDNA of 2841 bp and an open reading frame encoding a putative protein of 632 amino acids. Through multiple sequence alignment and phylogenetic analysis, it was revealed that LvHSF1 was closed to insect HSF family, which contained a highly conserved DNA-binding domain, oligomerization domains with HR-A/B, and a nuclear localization signal. Tissues distribution showed that LvHSF1 was widely expressed in all tissues tested. And it was upregulated in hemocytes and gills after Vibrio alginolyticus or Staphylococcus aureus infection. Dual-luciferase reporter assays indicated that LvHSF1 activated the promoters of L. vannamei HSP70 (LvHSP70) and L. vannamei Cactus (LvCactus), while inhibited the expressions of Drosophila antimicrobial peptide (AMP) Atta, Mtk, and L. vannamei AMP PEN4 through NF-κB signal transduction pathway modification. Knocked-down expression of LvHSF1 by dsRNA resulted in downregulations of LvHSP70 and LvCactus, as well as cumulative mortality decreasing under V. alginolyticus or S. aureus infection in L. vannamei. Taken together, our data strongly suggest that LvHSF1 is involved in LvHSP70 regulation, therefore plays a great role in stress resistance. And it also takes part in LvCactus/LvDorsal feedback regulatory pathway modification of L. vannamei, which is in favor of V. alginolyticus or S. aureus infection.

Expression of HSF2 in ulcerative colitis and other intestinal diseases

Objective To investigate the expression of HSF2 in colonic mucosa of patients with ul- cerative colitis （UC）, Crohn＇s disease （ C D）, intestinal tuberculosis （ ITB）, intestinal lymphoma （ IL）, infectious enteritis, Behcetg disease and normal control. Methods Intestinal tissue samples were retrieved from 2003 -2011 archived specimen at the Department of Pathology, and assigned to UC group （n = 38 ）, CD group （n =29）, ITB group （n =31 ）, IL group （n =32）, infectious enteritis group （n =32） and Beh- cet＇s disease group （n =28）. 10 cases were recruited as normal control group. The expression of HSF2 in colonic mucosa were detected by immunohistochemistry. Positive cells were counted by Image Analysis. Re- suits The expression rate of HSF2 in intestinal mucosa of UC patients （ 64. 64 ±15.17 ） was significantly higher than that of CD （ 32.44± 5.94 ）, ITB （ 36. 93 ±6. 32 ）, IL （ 36. 16 ±6. 55 ）, infectious enteritis （37.86 ±7. 76）, Behcet＇s disease （34. 90 ±5.92） and normal control （35.54 ±6. 76） （P 〈0. 05）, while there was no significant difference among the latter six groups （ P 〉 0. 05 ）. Conclusion HSF2 is closely re- lated with UC, and may play an important role in the pathogenesis, diagnosis and differential diagnosis of UC. Key words: Ulcerative colitis ; Heat shock factor 2 ; Immunohistochemistry

Glutamine‐mediated Dual Regulation of Heat Shock Transcription Factor‐1 Activation and Expression

Heat shock factor‐1 (HSF1) is the master regulator for cytoprotective heat shock protein (Hsp) expression. It is widely thought that HSF1 expression is non‐inducible and thus the key control point of HSP expression is regulation of HSF1's transactivation activity. How HSF1 expression is regulated remains unknown. Herein, we demonstrate that glutamine (Gln) enhanced Hsp expression both in rat colonic epithelium in vivo and in cultured non‐transformed colonic YAMC cells. This was associated with upregulated HSF1's transactivation activity via increased HSF1 trimerization, nuclear localization and DNA binding. Intriguingly, Gln enhanced HSF1 protein and mRNA expression and Hsf1 gene promoter activity. Within the −281/−200 region of the Hsf1 promoter, deletion of the putative CCAAT enhancer binding protein (C/EBP) binding site abolished Gln's HSF1 response. Gln availability strikingly altered the ratio of C/EBPβ inhibitory and active isoforms, i.e., liver‐enriched inhibitory protein (LIP) and liver‐enriched activating protein (LAP). LIP and LAP were further shown to be independent repressor and activator respectively for Hsf1 gene transcription and the relative abundance of these two C/EBPβ isoforms was demonstrated to determine Hsf1 transcription. We show for the first time that Gln not only enhances HSF1's transactivation, but also induces Hsf1 gene transcription in a C/EBPβ‐dependent manner.

Heat shock response improves heterologous protein secretion in Saccharomyces cerevisiae

The yeast Saccharomyces cerevisiae is a widely used platform for the production of heterologous proteins of medical or industrial interest. However, heterologous protein productivity is often low due to limitations of the host strain. Heat shock response (HSR) is an inducible, global, cellular stress response, which facilitates the cell recovery from many forms of stress, e.g., heat stress. In S. cerevisiae, HSR is regulated mainly by the transcription factor heat shock factor (Hsf1p) and many of its targets are genes coding for molecular chaperones that promote protein folding and prevent the accumulation of mis-folded or aggregated proteins. In this work, we over-expressed a mutant HSF1 gene HSF1-R206S which can constitutively activate HSR, so the heat shock response was induced at different levels, and we studied the impact of HSR on heterologous protein secretion. We found that moderate and high level over-expression of HSF1-R206S increased heterologous α-amylase yield 25 and 70 % when glucose was fully consumed, and 37 and 62 % at the end of the ethanol phase, respectively. Moderate and high level over-expression also improved endogenous invertase yield 118 and 94 %, respectively. However, human insulin precursor was only improved slightly and this only by high level over-expression of HSF1-R206S, supporting our previous findings that the production of this protein in S. cerevisiae is not limited by secretion. Our results provide an effective strategy to improve protein secretion and demonstrated an approach that can induce ER and cytosolic chaperones simultaneously.

Glutamine-mediated Dual Regulation of Heat Shock Transcription Factor-1 Activation and Expression

Regulation of transcriptional activity of heat shock factor-1 (HSF1) is widely thought to be the main point of control for heat shock protein (Hsp) expression. Glutamine increases Hsf1 gene transcription in a C/EBPβ-dependent manner and up-regulates HSF1 activity. Glutamine is an activator for both HSF1 expression and transactivation. Glutamine-induced HSF1 expression provides a novel mechanistic frame for HSF1-Hsp axis regulation. Heat shock transcription factor-1 (HSF1) is the master regulator for cytoprotective heat shock protein (Hsp) expression. It is widely thought that HSF1 expression is non-inducible, and thus the key control point of Hsp expression is regulation of the transactivation activity of HSF1. How HSF1 expression is regulated remains unknown. Herein we demonstrate that glutamine (Gln), a preferred fuel substrate for the gut, enhanced Hsp expression both in rat colonic epithelium in vivo and in cultured non-transformed young adult mouse colonic epithelial cells. This was associated with up-regulation of the transactivation activity of HSF1 via increased HSF1 trimerization, nuclear localization, DNA binding, and relative abundance of activating phosphorylation at Ser-230 of HSF1. More intriguingly, Gln enhanced HSF1 protein and mRNA expression and Hsf1 gene promoter activity. Within the -281/-200 region of the Hsf1 promoter, deletion of the putative CCAAT enhancer-binding protein (C/EBP) binding site abolished the HSF1 response to Gln. C/EBPβ was further shown to bind to this 82-bp sequence both in vitro and in vivo. Gln availability strikingly altered the ratio of C/EBPβ inhibitory and active isoforms, i.e. liver-enriched inhibitory protein and liver-enriched activating protein. Liver-enriched inhibitory protein and liver-enriched activating protein were further shown to be an independent repressor and activator, respectively, for Hsf1 gene transcription, and the relative abundance of these two C/EBPβ isoforms was demonstrated to determine Hsf1 transcription. We show for the first time that Gln not only enhances the transactivation of HSF1 but also induces Hsf1 expression by activating its transcription in a C/EBPβ-dependent manner.

Characterization of the Constitutive Pig Ovary Heat Shock Chaperone Machinery and Its Response to Acute Thermal Stress or to Seasonal Variations1

Reduced oocyte competence causes the lower fertility reported in domestic sows during the warm months of the year. Somatic cells express heat shock proteins (HSPs) to protect themselves from damage caused by thermal stress. HSPs are classified as molecular chaperones and control the correct folding of newly synthesized or damaged proteins. The present work performed a comprehensive survey of the different components of the heat shock chaperone machinery in the pig ovary, which included the HSP40, HSP70, HSP90, and HSP110 families, as well as heat shock factors (HSF) 1 and 2. Pig ovarian follicles constitutively expressed different members of these families; therefore, we examined their ability to respond to heat stress. In order to take into account the role of the complex follicular architecture, whole pig ovaries were exposed to 41.5°C for 1 h. This exposure significantly disrupted oocyte maturation and determined the upregulation of the HSP70, HSP40, HSPH1, HSPA4, HSPA4L, HSF1, and HFS2 genes, whereas expression levels of HSP90A and HSP90B, as well as those of genes unrelated to heat stress were not altered. Unexpectedly HSP and HSF expression levels changed only in oocytes but not in cumulus cells. Cumulus-oocyte complexes isolated from ovaries collected in summer showed the same pattern as those collected in winter. We conclude that the HSP chaperone machinery is constitutively fully operational in the pig ovary. However, following thermal stimuli or seasonal variations, cumulus cell HS-related gene expression remains unchanged, and only oocytes activate a response, suggesting why this mechanism is insufficient to preserve their competence both in vitro and in vivo.

Molecular modelling study to find inhibitors of HSF1 functional activity for cancer therapeutics: virtual screening and molecular docking approach

Molecular modelling study to find inhibitors of HSF1 functional activity for cancer therapeutics: virtual screening and molecular docking approach

A dominant-negative mutation of HSF2 associated with idiopathic azoospermia

Idiopathic azoospermia (IA) is a severe form of male infertility due to unknown causes. The HSF2 gene, encoding the heat shock transcription factor 2, had been suggested to play a significant role in the spermatogenesis process since the Hsf2-knockout male mice showed spermatogenesis defects. To examine whether HSF2 is involved in the pathogenesis of IA in human, we sequenced all the exons of HSF2 in 766 patients diagnosed with IA and 521 proven fertile men. A number of coding mutations private to the patient group, which include three synonymous mutations and five missense mutations, were identified. Of the missense mutations, our functional assay demonstrated that one heterozygous mutation, R502H, caused a complete loss of HSF2 function and that the mutant suppressed the normal function of the wild-type (WT) allele through a dominant-negative effect, thus leading to the dominant penetrance of the mutant allele. These results support a role for HSF2 in the pathogenesis of IA and further implicate this transcription factor as a potential therapeutic target.

Heat Shock Factor Hsf1 Cooperates with ErbB2 (Her2/Neu) Protein to Promote Mammary Tumorigenesis and Metastasis

ErbB2/Neu oncogene is overexpressed in 25% of invasive/metastatic breast cancers. We have found that deletion of heat shock factor Hsf1 in mice overexpressing ErbB2/Neu significantly reduces mammary tumorigenesis and metastasis. Hsf1(+/-)ErbB2/Neu(+) tumors exhibit reduced cellular proliferative and invasive properties associated with reduced activated ERK1/2 and reduced epithelial-mesenchymal transition (EMT). Hsf1(+/+)Neu(+) mammary epithelial cells exposed to TGFβ show high levels of ERK1/2 activity and EMT; this is associated with reduced expression of E-cadherin and increased expression of Slug and vimentin, a mesenchymal marker. In contrast, Hsf1(-/-)Neu(+) or Hsf1(+/+)Neu(+) cells do not exhibit activated ERK1/2 and show reduced EMT in the presence of TGFβ. The ineffective activation of the RAS/RAF/MEK/ERK1/2 signaling pathway in cells with reduced levels of HSF1 is due to the low levels of HSP90 in complex with RAF1 that are required for RAF1 stability and maturation. These results indicate a powerful inhibitory effect conferred by HSF1 downstream target genes in the inhibition of ErbB2-induced breast cancers in the absence of the Hsf1 gene.

Inactivation of Heat Shock Factor Hsf4 Induces Cellular Senescence and Suppresses Tumorigenesis In Vivo

Studies suggest that Hsf4 expression correlates with its role in cell growth and differentiation. However, the role of Hsf4 in tumorigenesis in vivo remains unexplored. In this article, we provide evidence that absence of the Hsf4 gene suppresses evolution of spontaneous tumors arising in p53- or Arf-deficient mice. Furthermore, deletion of hsf4 alters the tumor spectrum by significantly inhibiting development of lymphomas that are normally observed in the majority of mice lacking p53 or Arf tumor suppressor genes. Using mouse embryo fibroblasts deficient in the hsf4 gene, we have found that these cells exhibit reduced proliferation that is associated with induction of senescence and senescence-associated β-galactosidase (SA-β-gal). Cellular senescence in hsf4-deficient cells is associated with the increased expression of the cyclin-dependent kinase inhibitors, p21 and p27 proteins. Consistent with the cellular senescence observed in vitro, specific normal tissues of hsf4(-/-) mice and tumors that arose in mice deficient in both hsf4 and p53 genes exhibit increased SA-β-gal activity and elevated levels of p27 compared with wild-type mice. These results suggest that hsf4 deletion-induced senescence is also present in vivo. Our results therefore indicate that Hsf4 is involved in modulation of cellular senescence, which can be exploited during cancer therapy.

Parallelism and paradoxes on viability and the life span of two loss-of-function mutations: Heat shock protein transcriptional regulator hsf 1 and l(2)gl tumor suppressor in Drosophila melanogaster

In this study we analyzed how a dosage decrease in mono- and diheterozygotes on both lethal alleles of the lgl-gene and hsfheat shock regulator influences viability and life span at optimal and high temperature 29 degrees C conditions. We found that hsf(1) (1 dosage of active hsf-factor) heterozygote animals had significantly increased viability (up to 30-39%) in case of its development from egg to imago under the stress of 29 degrees C. However, this stress-protective effect of a decreased dosage of HSF1 was suppressed in diheterozygotes, while the dosage of tumor suppressor lgl was simultaneously decreased. Under stress temperature conditions, a decrease in dosage of one of the alleles also increased the average life span and delayed aging, especially in the case of maternal inheritance of each of the loss-of-function mutations. In diheterozygotes the average life span had intermediate meanings. However, in diheterozygote males under stress conditions the positive longevity effect of hsf was suppressed in the presence of the lgl-mutation. Paradoxically, that decrease of expression of each of the studied vital genes provided a positive effect on both viability and life span under stress conditions. However, a simultaneous dosage decrease of two loss-of-function alleles in diheterozygotes resulted in disbalanced effects on the organism level. The received data indicate interaction between HSF1 and LGL gene products during ontogenesis and stress-defending processes.

Hsf1 Knock-out

In the recent article by Tranter et al. (1), it is indicated that homozygous Hsf1 (knock-out) mice are not viable. This information as mentioned was not supported by any reference. As statements provided in scientific papers need to be accurate, I would like to provide the following additional information and correction. The knock-out of the Hsf1 gene was actually first published in 1998 in JBC (2). Since then, several laboratories have independently generated several lines of Hsf1 knock-out mice (see MGI:96238). The knock-out of Hsf1 is mostly viable depending on the genetic background. Numerous studies using those animals have demonstrated the key roles played by HSF1 in reproduction, stress response, cardioprotection, etc.

Absence of mutations in four genes encoding for congenital cataract and expressed in the human brain in Tunisian families with cataract and mental retardation

BackgroundTo identify the genetic defect associated with autosomal recessive congenital cataract (ARCC), mental retardation (MR) and ARCC, MR and microcephaly present in most patients in four Tunisian consanguineous families.MethodsWe screened four genes implicated in congenital cataract by direct sequencing in two groups of patients; those affected by ARCC associated to MR and those who presented also microcephaly. Among its three genes PAX6, PITX3 and HSF4 are expressed in human brain and one gene LIM2 encodes for the protein MP20 that interact with the protein galectin-3 expressed in human brain and plays a crucial role in its development. All genes were screened by direct sequencing in two groups of patients; those affected by ARCC associated to MR and those who presented also microcephaly.ResultsWe report no mutation in the four genes of congenital cataract and its flanking regions. Only variations that did not segregate with the studied phenotypes (ARCC associated to MR, ARCC associated with MR and microcephaly) are reported. We detected three intronic variations in PAX6 gene: IVS4 -274insG (intron 4), IVS12 -174G>A (intron12) in the four studied families and IVS4 -195G>A (intron 4) in two families. Two substitutions polymorphisms in PITX3 gene: c.439 C>T (exon 3) and c.930 C>A (exon4) in one family. One intronic variation in HSF4 gene: IVS7 +93C>T (intron 7) identified in one family. And three intronic substitutions in LIM2 gene identified in all four studied families: IVS2 -24A>G (intron 2), IVS4 +32C>T (intron 4) and c.*15A>C (3'-downstream sequence).ConclusionAlthough the role of the four studied genes: PAX6, PITX3, HSF4 and LIM2 in both ocular and central nervous system development, we report the absence of mutations in all studied genes in four families with phenotypes associating cataract, MR and microcephaly.