Human Hair Graying Revisited: Principles, Misconceptions, and Key Research Frontiers

Decoding driver and phenotypic genes in cancer: Unveiling the essence behind the phenomenon

Gray hair, widely regarded as a hallmark of aging. While gray hair is associated with aging, reversing this trait through gene targeting does not alter the fundamental biological processes of aging. Similarly, certain oncogenes (such as CXCR4, MMP-related genes, etc.) can serve as markers of tumor behavior, such as malignancy or prognosis, but targeting these genes alone may not lead to tumor regression. We pioneered the name of this class of genes as "phenotypic genes". Historically, cancer genetics research has focused on tumor driver genes, while genes influencing cancer phenotypes have been relatively overlooked. This review explores the critical distinction between driver genes and phenotypic genes in cancer, using the MAPK and PI3K/AKT/mTOR pathways as key examples. We also discuss current research techniques for identifying driver and phenotypic genes, such as whole-genome sequencing (WGS), RNA sequencing (RNA-seq), RNA interference (RNAi), CRISPR-Cas9, and other genomic screening methods, alongside the concept of synthetic lethality in driver genes. The development of these technologies will help develop personalized treatment strategies and precision medicine based on the characteristics of relevant genes. By addressing the gap in discussions on phenotypic genes, this review significantly contributes to clarifying the roles of driver and phenotypic genes, aiming at advancing the field of targeted cancer therapy.

miRNA-200a suppresses GNAI1 and PLCB4 to modulate skin pigmentation in cashmere goats

Coat colour formation in mammals is influenced by melanogenesis and pigmentation processes regulated by miRNAs, including miRNA-200a. Although miRNA-200a is differentially expressed in the skin of cashmere goats with varying coat colours, its regulatory mechanism remains unclear. In this study, miRNA-200a target genes were predicted using miRBase and TargetScan, identifying GNAI1 and PLCB4 as the target genes through GO and KEGG analyses. Dual-luciferase assays using wild-type and mutant plasmids confirmed a direct interaction between miRNA-200a and the 3'UTR regions of these genes. RT-qPCR and Western blot analyses demonstrated that the expression levels of miRNA-200a and its target genes differed significantly between black and white goat skin. In HaCaT cells, transfection with miRNA-200a mimics or inhibitors altered GNAI1 and PLCB4 expression at both mRNA and protein levels. To validate these findings in vivo, subcutaneous injection of antagomiR-200a into BALB/c mice significantly reduced melanin content (P < 0.01) and increased the expression of GNAI1 and PLCB4. These results indicate that miRNA-200a modulates skin pigmentation by suppressing GNAI1 and PLCB4, thereby influencing coat colour in cashmere goats. This study provides a foundational understanding for leveraging genetic regulation to enhance coat colour diversity and develop naturally pigmented breeds.

Neurological Mechanisms Exploration and Therapeutic Targets in Segmental Vitiligo Accompanied by White Hair

Vitiligo is the most common skin depigmentation disease, affecting 0.1%-2% of people in the world. 3.5%-20.5% of segmental patients account for the total number of vitiligo patients. It has been clinically observed that segmental vitiligo patients are more likely to generate white hair, which may be related to neuroendocrine factors. The color of human skin and hair is affected by the number and functional status of melanocytes. Vitiligo affects patients' physical and mental health due to the shame it causes from the white patches and hair. This article reviews the underlying mechanisms of segmental vitiligo with white hair based on skin and hair follicle melanocytes. The article attempts to propose possible targets for the treatment of this disease.

Deciphering the role of skin aging in pigmentary disorders

Skin aging is a complex biological process involving intrinsic and extrinsic factors. Skin aging contains alterations at the tissue, cellular, and molecular levels. Currently, there is increasing evidence that skin aging occurs not only in time-dependent chronological aging but also plays a role in skin pigmentary disorders. This review provides an in-depth analysis of the impact of skin aging on different types of pigmentary disorders, including both hyperpigmentation disorders such as melasma and senile lentigo and hypopigmentation disorders such as vitiligo, idiopathic guttate hypomelanosis and graying of hair. In addition, we explore the mechanisms of skin aging on pigmentation regulation and suggest several potential therapeutic approaches for skin aging and aging-related pigmentary disorders.

SASH1 S519N Variant Links Skin Hyperpigmentation and Premature Hair Graying to Dysfunction of Melanocyte Lineage

A better understanding of human melanocyte (MC) and MC stem cell biology is essential for treating MC-related diseases. This study employed an inherited pigmentation disorder carrying the SASH1S519N variant in a Hispanic family to investigate SASH1 function in the MC lineage and the underlying mechanism for this disorder. We used a multidisciplinary approach, including clinical examinations, human cell assays, yeast 2-hybrid screening, and biochemical techniques. Results linked early hair graying to the SASH1S519N variant, a previously unrecognized clinical phenotype in hyperpigmentation disorders. In vitro, we identified SASH1 as a regulator in MC stem cell maintenance and discovered that TNKS2 is crucial for SASH1's role. In addition, the S519N variant is located in one of multiple tankyrase-binding motifs and alters the binding kinetics and affinity of the interaction. In summary, this disorder links both gain and loss of pigmentation in the same individual, hinting to accelerated aging in human MC stem cells. The findings offer insights into the roles of SASH1 and TNKS2 in MC stem cell maintenance and the molecular mechanisms of pigmentation disorders. We propose that a comprehensive clinical evaluation of patients with MC-related disorders should include an assessment and history of hair pigmentation loss.

Skin assessment in congenital untreated isolated GH deficiency

PURPOSE

The separation between the inside and outside through the skin was fundamental for the evolution of prevertebrates, which grow through extrapituitary circuits, to vertebrates, which grow through the somatotrophic axis, namely pituitary growth hormone (GH). and circulating IGF1.Individuals with untreated isolated growth hormone (GH) deficiency (IGHD) due to a mutation in the GH-releasing hormone receptor (GHRH) gene, residing in Itabaianinha, Brazil, are vulnerable to skin cancer and have reduced sweating. However other aspects of their skin physiology are still unknown. Our objectives were to evaluate the number of skin cancers, skin aging, and functional aspects of the skin in this IGHD cohort.

METHODS

Twenty-six IGHD individuals and 26 controls matched by age, sex, ethnicity, and occupation were submitted to a biochemical, dermatological and a functional skin assessment by the Multi Probe Adapter Cutometer® MPA 580.

RESULTS

There was no difference in the number of skin cancers and in the degrees of photodamage between the groups. The melanin content in the forearm was similar between the groups but was lower in the buttocks (p = 0.005), as well as skin resistance (p < 0.0001) and elasticity (p = 0.003), lower in the IGHD. There was no difference in hydration and sebum content between the two groups.

CONCLUSION

IGHD is apparently associated with a neutral profile in terms of skin cancer and photodamage, with similar melanin on the forearm and lower buttocks, lower skin resistance and elasticity, with hydration and sebum similar to controls.