GLP-1 agonists and hair loss: a call for further investigation

The widespread adoption of glucagon-like peptide-1 (GLP-1) agonists in treating type 2 diabetes mellitus (T2DM) and obesity has sparked investigations into their impact on hair health, an area characterized by diverse conjectures. Some propose potential risks such as disrupted hair growth cycles or premature androgenetic alopecia (AGA), while others suggest benefits linked to improved insulin sensitivity and enhanced scalp blood circulation. However, despite these theoretical underpinnings, clinical evidence linking GLP-1 agonists to hair loss remains sparse. The necessity for vigilant patient monitoring and collaborative efforts cannot be overstressed in comprehensively addressing any potential consequences of GLP-1 agonist therapy on hair health as their use continues to expand.

Update on hand-foot-and-mouth disease

Hand-foot-and-mouth disease is a viral exanthem caused, primarily by Coxsackie A16 and enterovirus 71 with typical clinical features of fever, painful papules and blisters over the extremities and genitalia and an enanthem involving ulceration of the mouth, palate, and pharynx. Other enteroviruses have recently been noted to cause severe neurologic illness and paralysis (enterovirus 68) with variable cutaneous features. A recent outbreak of Coxsackie A6 infection has been seen worldwide with cases reported in the United States, Japan, Southeast Asia, and Europe. These cases have caused extensive cutaneous disease variants, some of which are not previously recognized in Coxsackie infection, namely vesicobullous and erosive eruptions, extensive cutaneous involvement, periorificial lesions, localization in areas of atopic dermatitis or in children with atopic dermatitis (the so-called eczema coxsackium), Gianotti-Crosti-like lesions, petechial/purpuric eruptions, delayed onychomadesis, and palmoplantar desquamation. Finally, adult cases appear to occur with this form of hand-foot-and-mouth disease, likely due to fecal-oral transmission in a household setting.

GAB2 amplifications refine molecular classification of melanoma

PURPOSE

Gain-of-function mutations in BRAF, NRAS, or KIT are associated with distinct melanoma subtypes with KIT mutations and/or copy number changes frequently observed among melanomas arising from sun-protected sites, such as acral skin (palms, soles, and nail bed) and mucous membranes. GAB2 has recently been implicated in melanoma pathogenesis, and increased copy numbers are found in a subset of melanomas. We sought to determine the association of increased copy numbers of GAB2 among melanoma subtypes in the context of genetic alterations in BRAF, NRAS, and KIT.

EXPERIMENTAL DESIGN

A total of 85 melanomas arising from sun-protected (n = 23) and sun-exposed sites (n = 62) were analyzed for copy number changes using array-based comparative genomic hybridization and for gain-of-function mutations in BRAF, NRAS, and KIT.

RESULTS

GAB2 amplifications were found in 9% of the cases and were associated with melanomas arising from acral and mucosal sites (P = 0.005). Increased copy numbers of the KIT locus were observed in 6% of the cases. The overall mutation frequencies for BRAF and NRAS were 43.5% and 14%, respectively, and were mutually exclusive. Among the acral and mucosal melanomas studied, the genetic alteration frequency was 26% for GAB2, 13% for KIT, 30% for BRAF, and 4% for NRAS. Importantly, the majority of GAB2 amplifications occurred independent from genetic events in BRAF, NRAS, and KIT.

CONCLUSIONS

GAB2 amplification is critical for melanomas arising from sun-protected sites. Genetic alterations in GAB2 will help refine the molecular classification of melanomas.

Gab2-mediated signaling promotes melanoma metastasis

Metastatic melanoma is a disease with a poor prognosis that currently lacks effective treatments. Critical biological features of metastasis include acquisition of migratory competence, growth factor independence, and invasive potential. In an attempt to identify genes that contribute to melanoma pathogenesis, a genome-wide search using bacterial artificial chromosome array comparative genomic hybridization and single nucleotide polymorphism arrays in a series of 64 metastatic melanoma samples and 20 melanoma cell lines identified increased copy numbers of Gab2 located on 11q14.1. Gab2 is an adaptor protein that potentiates the activation of the Ras-Erk and PI3K-Akt pathways and has recently been implicated in human cancer; however, its role in melanoma has not been explored. In this study, we found that Gab2 was either amplified (approximately 11%) and/or overexpressed (approximately 50%) in melanoma. Gab2 protein expression correlated with clinical melanoma progression, and higher levels of expression were seen in metastatic melanomas compared with primary melanoma and melanocytic nevi. We found that overexpression of Gab2 potentiates, whereas silencing of Gab2 reduces, migration and invasion of melanoma cells. Gab2 mediated the hyperactivation of Akt signaling in the absence of growth factors, whereas inhibition of the PI3K-Akt pathway decreased Gab2-mediated tumor cell migration and invasive potential. Gab2 overexpression resulted in enhanced tumor growth and metastatic potential in vivo. These studies demonstrate a previously undefined role for Gab2 in melanoma tumor progression and metastasis.

Sirtuins and beta-cell function

Over the past century, there have been major advances in medicine, diet and living conditions that have substantially extended the health span of people in the developed world. Over the past decade or so, the science of ageing has made great strides in providing an understanding of the underlying causes of ageing and how diet and genes play into the ageing process. In this essay, we will review some of the recent advances made in the science of sirtuins and beta-cell biology, and discuss how we will apply this knowledge to further the progress of humankind in healthy ageing.

Embryonic cocaine exposure and corticosterone: serotonin(2) receptor mediation

Cocaine activates the mature hypothalamic-pituitary-adrenal (HPA) axis, increasing corticosterone concentrations in animals and humans and serotonin(2) receptors (5-HT(2)) are involved in this effect. Although prenatal cocaine exposure is associated with altered responsiveness of the HPA axis to "stress" and serotonergic compounds postnatally, it is unknown whether cocaine directly activates the embryonic HPA axis or if 5-HT(2) receptors are involved. Domestic chicken eggs with viable embryos were exposed to either the 5-HT(2) receptor agonist dimethoxyiodophenylaminopropane (DOI: 0.4, 0.8, or 1.2 mg/kg egg) or saline on embryonic day 18 (E18). In a second study, the 5-HT(2) antagonist ritanserin (0.3 mg/kg egg, a dose found effective against other effects of DOI or cocaine) or vehicle was administered on E17, prior to treatment on E18 with either saline or cocaine (5 injections of 12 mg/kg egg, equivalent to a total dose of 3.5 mg/egg). Radioimmunoassay was used to measure serum corticosterone from blood samples taken approximately 1-2 h after drug injections. DOI significantly raised corticosterone in a dose-related fashion. Cocaine-induced corticosterone elevations were blocked by pretreatment with ritanserin, whereas ritanserin by itself did not affect corticosterone concentrations. These data indicate that 5-HT(2) receptors are involved in cocaine's effect on the HPA axis during late chicken embryogenesis.

Mitochondrial DNA ligase function in Saccharomyces cerevisiae

The Saccharomyces cerevisiae CDC9 gene encodes a DNA ligase protein that is targeted to both the nucleus and the mitochondria. While nuclear Cdc9p is known to play an essential role in nuclear DNA replication and repair, its role in mitochondrial DNA dynamics has not been defined. It is also unclear whether additional DNA ligase proteins are present in yeast mitochondria. To address these issues, mitochondrial DNA ligase function in S.cerevisiae was analyzed. Biochemical analysis of mitochondrial protein extracts supported the conclusion that Cdc9p was the sole DNA ligase protein present in this organelle. Inactivation of mitochondrial Cdc9p function led to a rapid decline in cellular mitochondrial DNA content in both dividing and stationary yeast cultures. In contrast, there was no apparent defect in mitochondrial DNA dynamics in a yeast strain deficient in Dnl4p (Deltadnl4). The Escherichia coli ECO:RI endonuclease was targeted to yeast mitochondria. Transient expression of this recombinant ECO:RI endonuclease led to the formation of mitochondrial DNA double-strand breaks. While wild-type and Deltadnl4 yeast were able to rapidly recover from this mitochondrial DNA damage, clones deficient in mitochondrial Cdc9p were not. These results support the conclusion that yeast rely upon a single DNA ligase, Cdc9p, to carry out mitochondrial DNA replication and recovery from both spontaneous and induced mitochondrial DNA damage.

Ontogeny of glucocorticoid receptors in the hyperstriatum-hippocampus-parahippocampal area and optic tectum of the embryonic chicken (Gallus domesticus) brain

The importance of glucocorticoids and their perturbation during development is an active research area. Developmental insults, including direct and indirect consequences of exposure to drugs of abuse or withdrawal from them, may act upon or via the neuroendocrine axis of the pregnant experimental subject (e.g. rat) and/or directly upon the neuroendocrine axis of the embryo or fetus. The use of the domestic chicken embryo may constitute a good experimental subject for studying these effects in the absence of maternal influences. Thus, the pattern of brain glucocorticoid cytosolic receptors were characterized in an early developing brain region, the optic tectum (OT) and a later developing region with a different function, the hyperstriatum-hippocampus-parahippocampal (HHP) area, on embryonic days (E) 11, 15, 18 and on the day of hatching (HD). The influence of the glucocorticoid synthesis inhibitor metyrapone, injected into eggs on E14 and on E17, upon glucocorticoid receptors (on E15 and E18) was also studied to determine effects of a 'chemical adrenalectomy'. Receptors for this steroid are high on E11 and E15, decreasing as they approach the time of hatching, with the HHP generally showing greater numbers of specific binding sites for [3H]-corticosterone (CORT). Although metyrapone treatment did not alter the apparent number of receptors on E15, on E18 it unmasked receptors otherwise occupied by endogenous ligand(s) and/or induced their synthesis, resulting in significantly more receptors identified with [3H]-CORT. Nevertheless, the HHP continued to display more of these receptors than the OT on E15 and E18 after injection of metyrapone. These observations are consistent with the hypotheses that the HHP of embryos of this species contains a higher density of glucocorticoid receptors than does the OT; that glucocorticoid receptor quantification is related to steroid synthesis inhibition in late embryonic development; and that neuroendocrine feedback control of serum glucocorticoids may become functional between E15 and E18. The results also suggest the use of this experimental approach for assessing the effects of developmental insults with drugs, other than metyrapone, as a marker for altered neuroendocrine development and/or function.

Point mutations in Italian patients with classic, non-classic, and cryptic forms of steroid 21-hydroxylase deficiency

Seventy-three Italian patients affected by steroid 21-hydroxylase deficiency were studied by a PCR-allele-specific oligonucleotide protocol in order to evaluate the presence of eight known point mutations. The majority of chromosomes were found to carry point gene conversions normally present in the pseudogene. Within the classic form, the most common mutations were the splicing mutation A/C-655 to G in intron 2 (34.2%), the nonsense mutation C-1993 to T in exon 8 (10.8%), and the missense mutation T-999 to A in exon 4 (10%). Within the non-classic form, the missense mutation G-1683 to T was the most common (57.7%). Other mutations were either absent, such as the three clustered missense mutations T-1380, T-1383, T-1389 to A in exon 6, or very rare, like the 1761 + T in exon 7 and the C-2108 to T in exon 8. Family genotyping revealed the presence of ten asymptomatic parents carrying mutations in both chromosomes, thus identifying the gene defect in cryptic subjects. Interestingly, the same mutations were found in both symptomatic and asymptomatic forms.